review article the nomad experiment at cern · 2019. 7. 31. · e nomad detector was located at the...

Review ArticleThe NOMAD Experiment at CERN

F Vannucci

LPNHEAPC Universite Paris 7-Diderot 4 place Jussieu 75005 Paris France

Correspondence should be addressed to F Vannucci vannucciin2p3fr

Received 19 June 2013 Revised 9 September 2013 Accepted 11 October 2013 Published 20 January 2014

Academic Editor Leslie Camilleri

Copyright copy 2014 F Vannucci This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited Thepublication of this article was funded by SCOAP3

The purpose of this paper is to review the experimental apparatus and some physics results from the NOMAD (neutrino oscillationmagnetic detector) experiment which took data in the CERN wide-band neutrino beam from 1995 to 1998 It collected andreconstructed more than one million charged current (CC) ]

120583events with an accuracy which was previously obtained only with

bubble chambers The main aim of the experiment was to search for the oscillation ]120583into ]

120591 in a region of mass compatible

with the prescriptions of the hot dark matter hypothesis which predicted a ]120591mass in the range of 1ndash10 eVc2 This was done by

searching for ]120591CC interactions observing the production of the 120591 lepton through its various decay modes by using kinematical

criteria In parallel NOMAD also strongly contributed to the study ofmore conventional processes quasielastic events strangenessproduction and charm dimuon production single photon production and coherent neutral pion production Exotic searches werealso investigated The paper reviews the neutrino beam the detector setup the detector performances the neutrino oscillationresults the strangeness production the dimuon charm production and summarizes other pieces of research

1 Motivation

When it was proposed the experiment was motivated by the-oretical arguments suggesting that the ]120591 may have a mass of1 eVc2 or higher and therefore could be themain constituentof the dark matter in the UniverseThis suggestion was basedon two assumptions

(i) the interpretation of the solar deficit in terms of ]119890 rarr]120583 oscillations amplified by matter effects inside theSun giving Δ1198982 sim 10

minus5 eV2c4(ii) the so-called ldquosee-sawrdquo mechanism which predicted

that neutrino masses are proportional to the squareof the mass of the charged lepton or the charge 23quark of the same family

Furthermore in analogy with quark mixing neutrinomixing angles were expected to be small This defined theregion to search for the corresponding oscillation

To fulfill this program the NOMAD detector measuredand identified most of the particles charged and neutralproduced in neutrino interactions The active target was aset of drift chambers with a fiducial mass of about 27 tons

and a low average density (99 kgm3) comparable to liquidhydrogen The detector was located in a dipole magnet for-merly used by theUA1 experiment giving a field of 04 TThisallowed a determination of the momenta of charged particlesvia their curvature withminimal degradation due tomultiplescattering The active target was followed by a transitionradiation detector to identify electrons an electromagneticcalorimeter including a preshower a hadronic calorimeterand finally a muon system

The 120591 was searched for via its CC interactions ]120591 +119873 rarr

120591+119883 Given the lifetime of the 120591minus and the energies consideredhere the 120591minus travelled about 1mm before decayingThe spatialresolution of NOMAD while good was not sufficient torecognize the nonzero impact parameter associatedwith suchtracks Instead the decay of the 120591

minus was identified usingkinematical criteria based on a precise measurement ofthe missing transverse momentum in the final state Thisrequired a detector with accurate energy and momentumresolution good particle identification and sophisticatedanalysis schemes

In order to be sensitive to a large fraction of the 120591minus decaymodes and to be able to select events with high acceptance

Hindawi Publishing CorporationAdvances in High Energy PhysicsVolume 2014 Article ID 129694 20 pageshttpdxdoiorg1011552014129694

2 Advances in High Energy Physics

and low backgrounds the NOMAD detector had to fulfill thefollowing criteria

(i) measurement of the momenta of charged particleswith good precision and

(ii) identification and measurement of electrons pho-tons and muons

The excellent performances of the NOMAD detectorfulfilled these goals

In addition to searching for neutrino oscillations thelarge sample of well-reconstructed data collectedwith a targethaving the density of a hydrogen bubble chamber permittedto study many other processes involving neutrinos

The Monte Carlo (MC) simulation used throughout thisstudy was based on modified versions of LEPTO 61 andJETSET 74 generators for neutrino interactions and on aGEANT-based program for the detector response

2 The Beam

The NOMAD detector was located at the CERN west areaneutrino facility (WANF) and was exposed to the SPSwide-band neutrino beam consisting predominantly of ]120583rsquosThe beam line has been operating for 20 years and wasreoptimized in 1992-1993 for the NOMAD and CHORUSexperiments Details of operations are given in [1]

The neutrinos were predominantly produced from thedecays in flight of the secondary 120587 and119870mesons originatingfrom the 450GeV protons impinging on a beryllium targetThe SPS cycle was repeated every 144 s The protons wereextracted from the SPS in two 4ms long spills separated by26 s with a 20 s ldquoflat toprdquoThe beam line operated with recordintensities up to 18 1013 protons in each of the two spillsDuring the four years of data taking 1995ndash1998 NOMADcollected a total of 22 1019 protons incident on the target

The target station consisted of 11 beryllium rods sepa-rated by 9 cm gaps Each rod was 10 cm long and 3mm indiameter positioned longitudinally along the proton lineThe secondary pions and kaons were focused by a pair ofcoaxial magnetic lenses called the horn and the reflectorIn such a system charged particles were deflected by thetoroidal field between two coaxial conductors carrying equaland opposite currents so that the focusing of particles ofone sign implied defocusing particles of the opposite sign Inorder to harden the neutrino spectrum the horn and reflectorwere displaced 20m and 90m from the target respectivelyThe higher neutrino energy increased the sensitivity of theexperiment to charged current ]120591 interactions which have anenergy threshold of 35 GeV The sections between the hornand the reflector and between the reflector and the decaytunnel were enclosed in helium tubes of 80 cm diameter anda total length of about 60m in order to reduce the absorptionof secondary particles Collimators reduced the antineutrinoscontamination by intercepting the defocused secondaries

The mesons were allowed to decay in a 290m longvacuum tunnel Shieldingmade from iron and earth followedIts usewas to range outmuons and absorb hadrons A toroidalmagnet operated at 3 kA located at the entrance of the iron

shielding deflected muons which would pass outside theshielding The NOMAD detector was located 835m from thetarget The average distance between the meson decay pointsand NOMAD was 620m

A neutrino beam monitoring system based on the detec-tion of muon yields at several depths into the iron shield wasbuilt Silicon detectors provided an absolute flux measure-ment An independent measurement of the flux was given bythe number of protons incident on the target estimated froma pair of beam current transformers (BCT) upstream of thetarget

A detailed GEANT simulation of the beam line pre-dicted the neutrino energy and radial position distribu-tions Figure 1 shows the neutrino flux for 109 protonson target The Monte Carlo simulation predicted the rela-tive abundance of neutrino species ]120583 anti]120583 ]119890 anti]119890 =100 0061 00094 00024 with average energies of 235 192371 and 313 GeV respectively

Since the search consisted in observing ]120591 interactions itwas essential to calculate the intrinsic ]120591 component in thebeam This component came from the prompt reactions

119901 + 119873 997888rarr 119863119904 + 119883

followed by 119863119904 997888rarr 120591 + ]120591 120591 997888rarr ]120591 + 119883

(1)

The relative number of ]120591 produced from the abovereactions and interacting via the CC channel in the fiducialvolume of NOMAD was estimated to be 5 10minus6 with respectto ]120583CC interactions The resulting intrinsic ]120591 signal wasmuch less than one event in the total duration of theNOMADexperiment

3 The Detector

The detector is shown schematically in Figure 2 It consistedof a number of subdetectors most of which were located in alarge dipole magnet having an inner volume of 75m alongthe beam axis and 35 times 35m2 in transverse dimensionsThecoordinate system adopted for NOMAD had the 119909-axis intothe plane of the figure the 119910-axis directed up towards thetop of the detector and the 119911-axis horizontal approximatelyalong the direction of the neutrino beam The beam linepointed upwards at an angle of 24∘ with the 119911-axis Themagnetic field was along the 119909-axis and had a value of04 T

Moving downstream along the beam direction camea veto counter a front calorimeter a large active targetconsisting of drift chambers a transition radiation detec-tor a preshower an electromagnetic calorimeter a hadroncalorimeter and an iron filter consisting in the return-yokeof the magnet followed by a set of large drift chambersused for muon identification Upstream and downstreamof the transition radiation detector two large hodoscopesof scintillators provided a fast trigger The key featuresof each subdetector are given below Overall the detectorreconstructed the events kinematics with great precision andidentified electrons muons and photons

Advances in High Energy Physics 3

(a) (b)

(c) (d)

Figure 1 Fluxes of the various neutrino species in the NOMAD detector for 109 protons on target (from [1])

31 Veto Counters The veto system consisted of an arrange-ment of 59 scintillation counters covering an area of 5 times

5m2 at the upstream end of the detector The counters werearranged in a geometry which provided optimal rejection ofcharged particles produced in neutrino interactions upstreamof NOMAD for example in the iron magnet support andlarge-angle cosmic rays travelling in the same or the oppositedirection to the neutrino beam

The two photomultiplier outputs connected to eachscintillator counter were fed to the inputs of mean-timermodules the timing of which provided an output signalindependent in time of the position at which the detected

charged particle traversed the counter The charged particlerejection efficiency of the NOMAD veto was constantlymonitored and remained stable at a level of 96-97 Averagedover the two neutrino spills the contribution of the vetosystem to the overall dead time of NOMAD was 4

32 The Front Calorimeter (FCAL) The detector was sus-pended from iron pillars at the two ends of the magnetThe front pillar was instrumented with scintillator planesto provide an additional massive active target for neutrinointeractionsThe FCAL consisted of 23 iron plates and 49 cmthick and separated by 18 cm gaps Twenty out of the 22 gaps


chambersMuon

beamNeutrino

calorimeterHadronic

modulesTRD

Dipole magnet

Trigger planesElectromagneticcalorimeterDrift chambers

calorimeterFront

Veto planes

x

y

z

1m

otimes

otimes B = 04T

V8

Preshower

Figure 2 A schematic sideview of the detector

were instrumented with long scintillators read out on bothends The dimensions of the scintillators were 175 times 185 times

06 cm3The FCAL had a depth of about 5 nuclear interaction

lengths and a total mass of about 177 tons A minimumionizing particle traversing the whole FCAL had an equiva-lent hadronic energy of 430MeV The FCAL was particularlyuseful for the study of charm dimuon production

33 The Drift Chambers (DC) The drift chambers [2] were acrucial part of the detectorThey provided the target materialand the tracking device for the particles They were designedwith the conflicting requirements that their walls should beas heavy as possible in order to maximize the number ofneutrino interactions and as light as possible in order tominimize multiple scattering of particles secondary particleinteractions and photon conversions To minimize the totalnumber of radiation lengths (1198830) for a given target massthe chambers were made of low density and low atomicnumber materials The complete target consisted of 145 driftchambers with a total mass of 29 tons over a fiducial areaof 26 times 26m2 Each chamber contributed 0021198830 Overallthe target had a density of 01 gcm3 and a total length of10X0 there was less than 0011198830 between two consecutive hitmeasurements in the chamber planes

The chambers were built on panels made of aramid fibresin a honeycomb structure These panels were sandwichedbetween two Kevlar-epoxy resin skins These skins gave themechanical rigidity and flatness necessary over the large3 times 3m2 surface area Each drift chamber consisted of fourpanels The three 8mm gaps between the panels were filledwith an argon-ethane (40ndash60) mixture at atmosphericpressure The gas was circulating permanently in a closedcircuit with a purifier section that removed oxygen and watervapor

The central gap was equipped with sense wires at +5∘ andminus5∘ with respect to the magnetic field direction These sensewires were 20 120583m in diameter and were made of gold-platedtungsten They were interleaved with 100 120583m potential wiresmade of Cu-Be These wires were equally spaced vertically to

provide drift cells of plusmn32 cm around each sense wire Fieldshaping aluminum strips were printed on mylar glued to thepanelsThe 3m long wires were glued to support rods at threepoints to keep them at a constant 4mm distance from thecathode planes The gap was maintained at 8mm using ninespacers facing melanine inserts embedded in the honeycombstructure of the panels The potential wires were held atminus3200V and the anode wires at +1750V The potentials onthe strips provided a drift field of 1 kVcm With this electricfield and the gasmixture used the ionization electrons driftedwith a velocity of about 50mm120583s In order to compensate forthe Lorentz angle and to keep a drift direction parallel to theplanes when the magnetic field was turned on the potentialson the strips were set at different values on the two sides ofeach gap

There were 49 chambers in the complete detector eachcorresponding to 147 sense wire planes for a total of 6174wires The target chambers were mounted in 11 modules offour chambers in the front part of the detector and fiveadditional chambers were installed individually in the TRDregion and were used to improve the lever arm for trackingand for better extrapolation of the tracks to the rest of thesubdetectors

The typical wire efficiency was 97 most of the lossbeing due to the supporting rods Wire signals were fedto a preamplifier and a fast discriminator allowing trackseparation down to 1mm The spatial resolution was studiedusing straight tracks (muons) crossing the detector duringdata takingThe distribution of residuals was obtained after acareful alignment of all wires as well as a detailed descriptionof the time-to-distance relationThe distribution had a sigmaof about 150120583mThe 5∘ stereo angles gave a resolution alongthe wires of 15mm

The momentum resolution provided by the drift cham-bers was a function of momentum and track length Forcharged hadrons and muons travelling normal to the planeof the chambers it was parameterized as

120590119901

119901

sim

005

radic (119871)

+

0008pradic(1198715)

(2)


Primary vertex (data)

Entr

ies

0

500

1000

1500

2000

2500

3000

3500

4000

4500skins

Kevlar

Gas

gap

Hon

eyco

mb

Hon

eyco

mb

Hon

eyco

mb

Hon

eyco

mb

Gas

gap

Gas

gap

minus5 minus4 minus3 minus2 minus1 0 1 2 3 4 5z (cm)

Figure 3 Distribution of vertices through one drift chamber alongthe beam direction (from [3])

where the momentum 119901 is in GeVc and the track length 119871 inmThe first term is the contribution frommultiple scatteringand the second term comes from the single hit resolutionof the chambers For a momentum of 10GeVc multiplescattering was the dominant contribution for track lengthslarger than 13m

The tracking was more difficult for electrons as they radi-ated photons via bremsstrahlung process as they traversed thenonzero-density tracking system This resulted in a contin-uously changing curvature In this case the resolution wasworse and electron energies were measured by combininginformation from the drift chambers and the electromagneticcalorimeter

Most neutrino interactions in the NOMAD active tar-get occurred in the passive panels of the drift chambersInteraction vertices were reconstructed by extrapolating thetracks of charged secondary interaction products Figure 3shows the distribution of vertices along the beam directionshowing the structure of a set of DCrsquos The eight ldquospikesrdquo inthis distribution correspond to the Kevlar skins of the DCrsquosRegions with a low interaction rate correspond to the threegas-filled drift gaps of the honeycomb panels This figuredirectly shows the vertex reconstruction resolution

34 The Trigger Counters Two trigger planes were installedin the NOMAD detector The first followed the active targetand the second was positioned behind the TRD region Eachof the planes covered a fiducial area of 280 times 286 cm2 andconsisted of 32 scintillation counters The scintillators had athickness of 05 cm and a width of 199 cm Twenty-eight ofthe counters were installed horizontally and had a length of124 cm In order to increase the fiducial area of the triggerplanes four counters of 130 cm lengthwere installed verticallyto cover the light-guides of the horizontal counters

The scintillators were connected by adiabatic light-guidesto 16-dynode photomultipliers which were oriented parallelto the magnetic field The field of 04 T only reduced theresponse of the tubes by 30 They had an intrinsic timeresolution of 1 ns and a noise rate of less than 50Hz Acoincidence between the two planes was required for a validtrigger The average efficiency of the trigger counters forsingle tracks was determined with data and found to be(975 plusmn 01)

35 The Transition Radiation Detector (TRD) The NOMADTRD [4 5]was designed to separate electrons frompionswitha pion rejection factor greater than 103 for a 90 electronefficiency in the momentum range from 1 to 50GeVc Thisfactor together with the additional rejection provided by thepreshower and the electromagnetic calorimeter was speciallyneeded in the search for the electronic 120591 decay channel inorder to eliminate neutral current (NC) interactions in whichan isolated pion track could fake an electron

The large rejection factor required and the large lat-eral dimensions of the detector (285 times 285m2) madethe NOMAD TRD one of the largest transition radiationdetectors ever built Its design was optimized by detailedsimulation and after several test beam measurements Ittook into account two main experimental constraints thelimited longitudinal space inside the NOMAD magnet andthe requirement that there be less than 21198830 added betweentwo consecutive hit measurements in the drift planes

The TRD was located after the first trigger plane andconsisted of nine identical modules The first eight moduleswere paired into four doublets In order to provide a precisetrack extrapolation from the drift chamber target to thecalorimeter five drift chambers were embedded in the TRDone after each TRD doublet and one after the last module

Each TRD module included a radiator followed by adetection plane with the following design

(i) The radiator was a set of 315 polypropylene foils each15 120583m thick and 285 times 285m2 in area separatedby 250 120583m air gaps The foils were stretched on analuminum frame and embossed to ensure a regularspacing in spite of their large size and electrostaticeffects

(ii) The detection plane consisted of 176 vertical strawtubes each 3m long and 16mm indiameter separatedby 02mm The straw tubes were fed in parallelwith a xenon-methane (80ndash20) gas mixture Theywere made of two shifted 125 120583m thick ribbons ofaluminized mylar rolled and glued along a 16mmdiameter helix The sensitive anode was a 50 120583mdiameter gold-plated tungsten wire stretched with atension of 100 g

The signals from the 1584 straw tubes were fed intoamplifiers producing differential outputs The charge ADCswere read out by a VME system A test pulse system wasused to control the stability of the entire electronic chainContinuous calibration of the TRD was performed withthe help of 55Fe radioactive sources uniformly deposited


45

40

35

30

25

20

15

10

5

00 5 10 15 20 25

(au

)

10GeV pions

10GeV electrons

Energy (keV)

Figure 4 Energy deposited in the TRD straw tubes for pions andelectrons (from [4 5])

on a ribbon stretched horizontally in the middle of eachdetection plane

Electron identification in the TRD was based on thedifference in the total energies deposited in the straw tubes byparticles of different Lorentz factors (120574 = 119864119898119888

2) Chargedparticles with 120574 lt 500 deposited energy predominantly byionization losses whereas charged particles with 120574 gt 500

(mainly electrons) also produced transition radiation X-raysat the interfaces of the foils As a result a few photons in thekeV range were produced by an electron crossing a radiatorAbout 60 of the photons emitted from the radiator wereabsorbed in the detection planes due to the large cross-sectionof xenon for photons of a few keV Transition radiation X-rayenergy deposition was added to the ionization losses of theparent particle in the same straw tube because the emittedphotons peaked around the initial particle direction

The algorithm developed for electron identification wasbased on a likelihood ratio method Figure 4 shows thenormalized spectra (MC simulation) of energy deposited inthe TRD straw tubes by 10GeVc pions and electrons atnormal incidenceTheTRD simulationwas extensively testedin situ using muons crossing the detector during the flat topbetween two neutrino spills

A pion rejection factor greater than 1000 was obtainedwith the 9 TRD modules in the momentum range from 1 to50GeVc while retaining an electron efficiency of 90

36 The Preshower Detector (PRS) The PRS was located justin front of the electromagnetic calorimeter It was composedof two planes of proportional tubes (286 horizontal and288 vertical) preceded by a 9mm (161198830) lead-antinomyconverter

The proportional tubes weremade of extruded aluminumprofiles and glued to two aluminum end plates of 05mmthickness Each tube had a square cross-section of 9 times

9mm2 and the walls were 1mm thick The 30 120583m gold-plated tungsten anode was strung with a tension of 50 g Theproportional tubes operated at a voltage of 1500V with amixture of Ar-CO2 (80ndash20) Signals from each tube were

fed into charge preamplifiers the twelve preamplifier signalswere sent to ADCs

Large samples of straight through muons were collectedduring the flat top of the SPS cycle The fine granularityof the PRS assisted in the understanding of signals inthe calorimeter blocks caused by adjacent particles Oncethe clusters with an associated track had been removedthe remaining ones could be attributed to photons whichconverted in the PRS The resolution was estimated usingnegative pions from a test beam interacting in the lead of thePRS It was assumed that these interactions camemainly fromcharge exchangewith one of the photons froma1205870 convertingin the lead plate The rms resolution for these events was1 cm a value much smaller than the dimensions of a singletower of the electromagnetic calorimeter which allowed theuse of the PRS to determine the impact point of convertingphotons for the 70 of the photons which converted in thelead radiator Using the above value as the spatial resolutionof photons and the energy resolution of the electromagneticcalorimeter a rough estimation of the 1205870mass resolution wasfound to be 11MeVc2 which is in good agreement with theobserved 1205870 mass distribution

37 The Electromagnetic Calorimeter (ECAL) The search for]120591 events in NOMAD relied strongly on electron identifi-cation as well as on a very accurate determination of thetransverse momentum in the event While electron identifi-cation was performed using the TRD the ECAL was crucialto accurately measure electron and gamma energies from100MeV up to 100GeV and to help in the determination ofthe neutral component of the transverse momentum Thelarge energy range to be covered required a large dynamicrange in the response of the detector and of the associatedelectronics A lead-glass detector was chosen for its excellentenergy resolution and uniformity of response The ECAL[6 7] combined with the PRS was also used to help improvethe electron identification provided by the TRD

The ECAL consisted of 875 lead-glass Cherenkov coun-ters of the TF1-000 type arranged in a matrix of 35 rowsand 25 columns Each counter was a 191198830 deep block witha rectangular cross-section of 79 times 112mm2 The directionof the magnetic field perpendicular to the counter axisimposed severe constraints on the mechanical assembly ofthe light detection system The light detectors (two-stagephotomultiplier tetrodes with a typical gain of 40 in theoperating conditions) were coupled to the back face of thelead-glass blocks This face was cut at 45∘ with respect tothe block axis in such a way that the symmetry axis of thetetrodes formed an angle of 45∘ with respect to the fielddirection thus keeping the signal reduction caused by themagnetic field less than 20 This reduction was found tobe very constant and uniform A low-noise electronic chaincomposed of a charge preamplifier followed by a shaper anda peak sensing ADC provided a calorimeter response in adynamic range larger than 4000

A fast analog signal from each shaper was also providedfor time measurements in order to reject energy depositionsnot associated with triggered events The obtained time


resolution was a few ns for energy depositions larger than1GeV In addition the fast analog signals summed overgroups of 64 counters formed an ECAL trigger

Monitoring of the lead-glass response was performedusing two blue LEDrsquos per counter mounted on the same faceof the block on which the tetrodes were positioned Beforethe final assembly in NOMAD the lead-glass blocks wereindividually calibrated using a 10GeVc electron beam Theeffect of the field on the calibration was taken into accountby LEDmeasurements performedwith andwithoutmagneticfield

The linearity of the calorimeter response to electrons wasverified at the test beam in the energy range 15ndash80GeV Adetailed study of the energy resolutionwas performedA two-parameter fit of the energy resolution Δ119864119864 = 119886+119887radic(119864)with 119864 in GeV gave 119886 = (104 plusmn 001) and 119887 = (322 plusmn

007)The ECAL response as a function of the impact point

of the incoming electrons was measured to be uniformwithin plusmn05 the response to electrons entering at normalincidence in the gaps between adjacent blocks showed thatECALwas ldquohermeticrdquo at more than 99 Aweak dependenceof the total energy release on the angle of incidence 120579 ofthe incoming electrons was found both in the test beammeasurements and in the MC simulations This dependencecould be attributed to the small variation with the angleof the Cherenkov light collection efficiency In additionthe number of towers receiving contributions from a givenshower increased with angle However this did not affectthe overall energy resolution that remained insensitive toboth shower position and angle The shower position wasmeasured with an average resolution of about 4mm in eachdirection

The calibration and the calorimeter response to lowenergy photons were checked by measuring the 1205870mass bothin a dedicated test beam and during theNOMADdata takingThe following results were found using test beam data

119898120587 = (1337 plusmn 12) MeVc2 with 120590119898 = 16MeVc2 (3)

The calorimeter response to muons corresponded to apeak value for the energy deposition of (0566 plusmn 0003) GeVThemuon signals were found to be stable within plusmn1 provid-ing an independent check of the stability in the calorimeterresponse

38 The Hadronic Calorimeter (HCAL) The HCAL wasintended to detect neutral hadrons and to provide ameasure-ment of the energy of charged hadrons complementary to thatderived frommomentummeasurements in the DCrsquos Knowl-edge of neutral hadrons was important when attributingkinematic quantities such as missing transverse momentumFurthermore calorimetric measurements of charged particleswere used both as a consistency check on the momentummeasurements of the charged particles and as an aid indistinguishing between muons and charged hadrons

The HCAL was an iron-scintillator sampling calorimeterThe downstream iron pillar of the magnet was instrumentedwith scintillators It consisted of 23 iron plates 49 cm thick

separated by 18 cm gaps six of these modules forming a wallof 54m wide 58m high and 15m deep This wall actedas a filter for the system of large muon chambers set updownstream

The active elements of the calorimeter were scintillatorpaddles 36m long 1 cm thick and 183 cm wide Taperedacrylic light pipes were glued to each end of the scintillatorpaddles to form an assembly 552m long Eleven of theseassemblies were threaded horizontally through the first 11gaps in the iron wall to form a calorimeter module 183 cmhigh and approximately 31 interaction lengths deep Scintil-lation light was directed through adiabatic light guides to a 5inch phototube at each end of the module Eighteen of thesemodules were stacked vertically to form a calorimeter with anactive area 36m wide by 35m high

The energy deposited in a given module was obtainedfrom the geometric mean of the two phototube signals andthe horizontal position of the energy deposit was determinedfrom the attenuation length of the scintillator and the ratioof the phototube signals Vertical positions were determinedfrom the pattern of energy sharing between the modulesTheenergy response to muons which traversed the calorimetergave a peak corresponding to the minimum ionizing distri-bution at 15 GeV with the expected Landau shape

Typical position resolutions were of the order of 20 cmin the horizontal projection There was a high probabilityfor hadrons to begin showering upstream of the hadroncalorimeter and so the total hadronic energy was taken to bea weighted sum of the energies deposited in the hadron andelectromagnetic calorimeters

39 The Muon Chambers The NOMAD muon detectorconsisted of 10 drift chambers previously used in the UA1experiment Each chamber had an active area of 375 times

555m2 with two planes of drift tubes in the horizontal andtwo in the vertical directions In total there were 1210 drifttubes each with a maximum drift distance of 7 cm

The chambers were arranged in pairs (modules) for tracksegment reconstruction The first muon station consisted ofthreemodules andwas placed behind the hadron calorimeterIt was followed by an 80 cm thick iron absorber and a secondmuon station of two modules

The chambers were operatedwith an argon-ethane (40ndash60) gas mixture Their performance was monitored con-tinuously using high energy muons passing through thedetector The average position resolution for hits was in therange of 350ndash600120583m depending on the gas quality Theaverage hit efficiency was 925 and the dominant source ofinefficiency (65) was due to dead areas between the drifttubes

Track segments were reconstructed separately for eachstation from typically 3 or 4 hits per projectionThemeasuredefficiency for the reconstruction of track segments was97

310 Triggering and Data Acquisition System The triggerlogic [8] was performed by a VME-based module which wasespecially designed for NOMADThe following triggers wereset up for the study of neutrino interactions in NOMAD


(i) VT1T2 This trigger allowed a study of neutrinointeractions in the DC target region At least onehit in both trigger planes T1 and T2 was requiredTo prevent triggering on through-going muons nohit should have occurred in the veto counters (V)The rate for this trigger was sim501013 pot and thelifetime was (86 plusmn 4) Of these 5 triggers about05 were potentially interesting candidates for neu-trino interactions in the DC The remaining triggersconsisted of 1 ldquocosmicsrdquo 15 nonvetoed muons and 2neutrino interactions in the magnet

(ii) V8FCAL Neutrino interactions in the front cal-orimeter with an energy deposition of at least 4mipfired this trigger Through-going muons were vetoedby the veto subset V8 On average 65 neutrinointeractions occurred in the FCAL for 1013 pot Thelifetime was (90 plusmn 3)

(iii) V8T1T2FCAL This trigger was set up to studyquasielastic-like events in the FCAL For this triggeran energy deposition between 1 and 3mip in theFCAL was requested The rate for this trigger wassim151013 pot and the lifetime was (90 plusmn 3)

(iv) T1T2ECAL The electromagnetic calorimeter wasalso used as a target Physics topics addressed withthese events included ]120583 rarr ]119890 and ]120583 rarr ]120591 oscilla-tions An energy deposition of more than sim10 GeV inthe ECAL enabled this trigger which had an averagerate of 21013 pot and a lifetime of (88 plusmn 3)

(v) RANDOM A random trigger allowed a study ofdetector occupancy

Approximately 15 neutrino candidate triggers were takenin each neutrino spill In addition various triggers were usedin the 26 s long flat-top between the two neutrino burstsThese were used for drift chamber alignment calibration ofthe different subdetectors and measurement of the triggercounter efficiency In total about 60 triggers were takenin each flat top NOMAD operated in burst mode wheretriggers arrive in short intervals (spills) separated by relativelylong intervals without beam Signals from each subdetectorarrived at some combination of the three types of FAST-BUS modules 12-bit charge-integrating ADCs 12-bit peak-sensing ADCs and 16-bit TDCrsquos There were a maximum of11648 channels to read out per event

Five VME-based boards controlled the readout of thefront-end electronics The VME controllers performed blocktransfers of the available data to local buffers assembledthe data into subevents and checked for consistency andintegrity They then passed the subevents through a VMEinterconnect bus to a sixth VME processor the ldquoeventbuilderrdquo which assembled all the pieces into complete eventstogether with information about the beam extraction andwrote them to one of two 9GB disks via a high-level network-ing package The event-builder stage also asynchronouslyreceived beam calibration data summaries of monitoringinformation and detector status information whenever theychanged

Monitoring programs for each of the nine subdetectors aswell as for beam scaler and trigger information connected tothe stages via Ethernet and generated summary histograms toverify the quality of the dataThe system recorded over 15MBof data per minute with a typical assembled neutrino eventcontaining around 2000 32-bit words before reconstructionDuring neutrino spills the data acquisition had a typical deadtime of 10 arising from digitizations The data-taking timelost due to downtime and interrun transitions was less than3

4 Detection Performances

Figure 5 shows a candidate ]120583 CC event detected inNOMADOne energetic particle penetrates to the muon chambers andsatisfies all other criteria to be a muon A hadronic jet ofcharged particles is clearly visible at the primary vertex anda photon conversion in the drift chambers is also evident

Figure 6 shows a candidate ]119890 CC event detected inNOMAD One very straight secondary track identified as anelectron by the TRD is seen to deposit a large amount ofenergy in a few cells of the ECAL as indicated by the largeldquobarrdquo in the event display

41 Identification of 1198700 1198700119904mesons observed in NOMAD

were used as a quality check of the reconstruction programand of the detector performance Using an algorithm lookingfor 1198810 vertices Figure 7 shows the 120587+120587minus mass distributionobtained from the neutrino beam data where the followingselection criteria were applied

(i) a pair of oppositely charged tracks not positivelyidentified as electrons or muons emerging from asecondary vertex distinct from the primary

(ii) the reconstructed momentum of the pair pointing tothe primary vertex

(iii) the invariant mass of the pair differing from the Λ0mass by more than 50MeVc2 when taken to be acombination 119901120587minus

The K0 peak stood out clearly over a small backgroundA fit gave a value for the mass of (4973 plusmn 04)MeVc2The resolution was 11MeVc2 consistent with the measuredmomentum resolution of NOMAD The proper distancetravelled by the 1198700

119904before decaying gave a lifetime of (892 plusmn

65)10minus13 s in agreement with the known value

42 Reconstruction of 1205870 Mesons Gamma rays from 1205870

decays represented the best electromagnetic probe availablein NOMAD to test the ECAL response The 1205870 flux was toosmall to allow individual calibration of each ECAL block butallowed a test of the overall energy response Figure 8 showsthe 2120574 invariant mass distribution obtained from the data fortwo-charged-tracks events with a vertex in theDC region andtwo neutral clusters in the ECAL The peak position is wellcentered on the 1205870 mass and the width (11MeVc2) is in goodagreement with the expected resolution


Figure 5 Candidate ]120583CC event reconstructed in the NOMAD detector


0

001

002

003

004

005

006

007

042 044 046 048 05 052 054 056 058

(au

)

MK (GeVc2)

120590 = 109 (MeVc2)MC mean = 4972

120590 = 112 (MeVc2)Data mean = 4979

Figure 7 120587+120587minus mass distribution showing the signal of 1198700 (from[9])

43 Muon Identification Muons were identified if they pen-etrated more than 8 interaction lengths of absorber materialin order to reach the first station or 13 interaction lengths forthe second station of the muon system For perpendicularincidence the momentum to reach the chambers was mea-sured to be 23GeVc for station 1 and 37GeVc for station2The geometrical acceptance to hit either of the two stationswas about 98This number applied to primary muons from]120583 CC interactions averaged over their production point

The muon momentum was measured in the centraldrift chambers with a precision of 3 for momenta below

0

20

40

60

80

100

120

140

160

180 Entries

Const

Mpi0

Std

BkgConst

BkgMean

BkgRMS

3211

106181

1175 plusmn 8175

01345 plusmn 07197E minus 03

01092E minus 01 plusmn 07399E minus 03

5197 plusmn 9839

minus1236 plusmn 08300E minus 01


0 01 02 03 04 05 062120574 invariant mass (GeV)

1205942ndf

Figure 8 2120574 invariant mass distribution showing the signal of 1205870(from [3])

20GeVc where the error was dominated bymultiple scatter-ing For largermomenta the error slowly rose asmeasurementerrors started to dominate but the muon charge couldbe reliably measured for momenta up to 200GeVc Themuon reconstruction efficiency was essentially momentumindependent above 5GeVc and reached more than 95

It was very important for many NOMAD analyses toidentify events which did not contain a muon Very lowmomentum muons could only be eliminated using kine-matical criteria such as 119901119879 cuts For muons well above thethreshold the efficiency to detect at least 2 out of 8ndash16possible hits was essentially 100 inside the muon chambergeometrical acceptance


44 Electron Identification TheNOMADTRDwas designedto separate electrons from heavier charged particles mainlypions A ldquohitrdquo in the TRD was a straw tube with an energyabove the pedestal value A set of hits collected along the roadaround a drift chamber track was associated with this trackEnergy depositions were then compared to the expectationsfor two possible hypotheses either electron or pion

Depending upon the topology of the event two differentidentification procedures were applied The signature of anisolated particle was defined from a likelihood ratio com-puted from the responses of all the straw tubes crossed by theincident track The momentum of the particle measured inthe DC was taken into account

The distributions of probability density that a givenenergy deposition belongs to an 119890 or 120587 were obtainedfrom detailed simulation extensive test beam and in situmeasurements A 120587 rejection better than 103 at 90 electronefficiency was achieved for isolated particles crossing all nineTRDmodules in awidemomentum range from 1 to 50GeVc

About 25 of ]119890 CC interactions lead to tracks havingldquosharedrdquo hits in the TRD An assignment of a total depositedenergy in shared hits to each of the nonisolated trackswould lead to particle misidentification The identificationprocedure for nonisolated particles took into account thenumber of tracks producing each hit and their momentaFor nonisolated tracks one had to consider four hypotheses120587(1199011) 120587(1199012) 119890(1199011) 120587(1199012)120587(1199011) 119890(1199012) and 119890(1199011) 119890(1199012) with1199011and 1199012 being the momenta of the tracks If two tracks had atmost three shared hits the particle identification procedurefor isolated tracks was applied to nonshared hits only Iftwo tracks had more than three shared hits four likelihoodestimators were computed for the energy depositions inshared hits from the corresponding two particle probabilitydistributions The decision on the nature of the tracks wasmade by selecting the hypothesis corresponding to themaximum likelihood value

The procedure allowed a correct identification of 84of the nonisolated 120587 produced in ]119890 CC interactions with15 of 120587120587 combinations being misidentified as 119890120587 and only1 as 119890119890 The performance of the identification algorithmswas studied on a sample of muons producing 120575-ray electronsabove 500MeVc With the electron identification algorithmfor isolated tracks (86plusmn3) of 120575-ray electrons were correctlyidentified at a 103 level of muon rejection

The electron identification also used the PRS and ECALin order to substantially improve the 120587119890 separation In a testbeam setup a rejection factor against pions of about 103 wasobtained in the energy range of 2ndash10GeV while retaining anoverall efficiency of 90 to detect electrons

5 Results on the ]120583rarr ]120591

Oscillation

The NOMAD experiment was designed to search for ]120591appearance from neutrino oscillations in the CERN beamFrom 1995 to 1998 the experiment collected 1040000 eventswith an identified muon corresponding to about 1350000 ]120583CC interactions given the combined trigger vertex identifi-cation and muon detection average efficiency of 77

The search for ]120583 rarr ]120591 oscillations was based on bothdeep inelastic (DIS) interactions and low-multiplicity (LM)events for all the accessible 120591 decay channels Details are tobe found in [10ndash13] The two samples were separated by acut on the total hadronic momentum 119901119867 at 15 GeVc Weconcentrate on the DIS analysis

51 Analysis Principle From the kinematical point of view]119890 CC events in NOMAD are fully characterized by the(undetected) decay of the primary 120591 The presence of visiblesecondary 120591 decay products here called 120591119881 allowed to dis-tinguish from NC interactions whereas the emission of one(two) neutrino(s) in hadronic (leptonic) 120591 decays provideddiscrimination against ]120591 (]119890) CC interactions

The search for ]119890 CC interactions was performed byidentifyingmost of the 120591 decays ]119890]120591 ℎ

minus]119890]120591 ℎminus(1198991205870) ]120591 and

ℎminusℎ+ℎminus(1198991205870) ]120591 for a total branching ratio of 828

First events containing a primary track identified as amuon were rejected Then neutrino interactions in the activetarget were selected by requiring the presence of at leastone track in addition to the 120591 decay products having acommon vertex in the detector fiducial volume Quality cutswere applied to ensure that the selected events were properlyreconstructed These requirements based on approximatecharge balance at the primary vertex and on the estimatedmomentum and energy errors removed 15 of these eventsThe candidate particle or system of particles 120591119881 consistentwith being produced in 120591 decays was then identified and theassociated hadronic system119867 was built

The kinematic selection in each 120591 decay mode was basedon a set of global variables which described the generalproperties of the momenta of the candidate 120591119881 and of thehadronic system 119867 in the laboratory frame The variableswere selected from the following list

(i) 119864vis is the total visible energy of the event

(ii) p120591119881and p119867 are the total momentum of the visible

tau decay product(s) and of the associated hadronicsystem respectively

(iii) 119864120591119881is the total energy of the visible tau decay prod-

uct(s)

(iv) p120591119879119881

and p119867119879

are the components of p120591119881

and p119867perpendicular to the neutrino beam direction

(v) p119898119879= minus(p120591

119879119881+ p119867119879) is the missing transverse momen-

tum due to neutrinos from 120591 decay

(vi) 119872119879 is the transverse mass

(vii) 119876119879 is the component of p120591119881perpendicular to the total

visible momentum vector

(viii) 120579]119879 is the angle between the neutrino direction andthe total visible momentum vector

(ix) 120579]119867 is the angle between the neutrino direction andthe hadronic jet

(x) 119882 is the invariant effective mass of the hadronicsystem


52 120591minus rarr 119890minus]119890]120591 The search for 120591minus started with the pre-

liminary identification of the prompt electron in events withno other prompt leptons followed by kinematical rejection ofbackgrounds

The identification of the electron candidate was per-formed according to strict criteria Primary electrons weredefined as DC tracks with 119901 gt 15GeVc associated with theprimary vertex and satisfying requirements based on theTRDidentification algorithm the PRS pulse height and the ECALcluster shape Also a consistency between the associatedelectromagnetic energy and the measured DC momentumof the candidate was required Overall these requirementsachieved a charged pion rejection factor of more than 104

Secondary electrons from Dalitz decays and from pho-tons converting close to the primary vertex were suppressedby requiring that the candidate electron did not form aninvariant mass of less than 50MeVc2 with any particle ofopposite charge

These requirements yielded an efficiency of 20 forprompt electrons from 120591

minus decays while accepting only29 10minus5 of ]120583 CC and 20 10minus4 of NC interactions

Then the kinematical selection proceededThe selection was performed by constructing likelihood

ratios which exploited the full topology of the event Thekinematic variables were chosen on the basis of their internalcorrelations which were globally taken into account by thelikelihood functions Events at this stage of the analysis weremostly ]119890 CC interactions with a genuine primary electronand NC events with an electron from photon conversion or1205870 Dalitz decay In ]119890 CC events the electron was typically

well isolated and balanced the momentum of the hadron jetin the transverse plane On the other hand in NC eventsthe electron was embedded in the hadron jet with transversemomentum almost aligned with it The search for signalhad intermediate properties between these two extremessince neutrinos carried away transverse momentum and thesizeable 120591 mass introduced a component of the electronmomentum perpendicular to the 120591 direction thus reducingits isolation

In order to distinguish the two background sources fromthe signal an event classification was implemented with theuse of two distinct likelihood functions The first one wasdesigned to separate signal from NC events and includedmainly longitudinal variables This was motivated by thesignificant contribution of these variables to the isolationof the electron candidate track For each event a likelihoodratio 120582NC

119890was defined as the ratio of the likelihood functions

constructed from signal andNCevents respectively Likewise120582CC119890

was defined This second function was designed todistinguish signal from ]119890 CC events It included informationon the transverse plane kinematics

The sensitivity was optimized in the plane (ln120582NC119890 ln 120582CC119890)

shown in Figure 9 for simulated signal and backgrounds Asignal region was defined at large values of both ln 120582NC

119890and

ln 120582CC119890 This corresponded to the selection of events where

the electron was isolated from the hadron jet but did notbalance it in the transverse plane The optimal sensitivity ofthe analysis lied in a region characterized by less than 05

background events Data were found to be consistent withbackground expectations inside the signal region indicatedby the boxes in the figure

In order to optimize the sensitivity to oscillations at lowΔ1198982 an independent analysis was performed with the LM

events sample The condition 119901119867 lt 15GeVc enriched theLM sample in quasielastic (QE) and resonance (RES) eventsavoiding double countingwith the correspondingDIS searchOverall the QE and RES events represented 63 of the total]120583 CC interactionsThe topology of LM events simplified thereconstruction and the selection criteria in this kinematicregion The prompt electron identification similar to thatused in theDIS search was applied to primaryDC trackswith119901 gt 2GeVc and was based on TRD and ECAL informationThe background consisted mostly of ]119890 interactions Detailsof the LM analysis are to be found in [10ndash13]

53 120591HadronicDecayChannels Thesearch for ]120591 appearancewas further improved by looking for other decaymodes of the120591 lepton This was achieved by looking for hadronic decaysAlso here two analyses were performed for the DIS andLM samples We discuss only the DIS analysis The differenthadronic decay modes were treated separately A muon vetowas implemented using both kinematical criteria and particleidentification

The search for 120591minus rarr ℎminus(1198991205870)]120591 decays where ℎ

minus is ahadron and 119899 ge 0 benefited from the large branching ratioof this mode Two independent analyses of the full inclusivesample were separately optimized for the exclusive 120591

minusrarr

120588minus]120591 and 120591

minusrarr ℎminus]120591 topologies

For 120591minus

rarr 120588minus]120591 the signal search started with the

identification of the 1205870 and 120587minus candidates produced in the

120588minus decay Each of the two photons from 120587

0 decay wasdetected either as neutral electromagnetic clusters or in caseit converted as two oppositely charged tracks forming asecondary vertex Thus the 1205870 was searched for either as twoseparate photons neutral clusters or conversions or in casethey coalesce in ECAL as two overlapped clusters

In each event all the possible 1205870 and 120587

minus combinationswere considered A 120587

minus candidate was a DC track with amomentum 119901 gt 1GeVc A 120587

0120587minus pair was considered as

a 120588 candidate if it had a reconstructed mass 06 lt 119872 lt

09GeVc2Likelihood functions based on the energies of the 1205870 and

of the 120587minus were defined Selecting the maximum likelihood

combination resulted in the correct choice in about 75 ofthe cases

The ]119890 CC interactions containing bremsstrahlung pho-tons not associatedwith the electron track could fake the 120591 rarr

120588 topologyThe electron veto used to reduce this backgroundfollowed the principles of themuon veto the highest and sec-ond highest 119901119879 tracks and the 120587minus candidate were consideredcandidate electrons The selection proceeded The rejectionof NC interactions was accomplished by using a likelihoodfunction based on the angles 120579]119879 and 120579]119867

The search was continued with the 120591minus rarr ℎminus]120591 channel

The ℎminus candidate was the highest 119901119879 negative primary trackprovided it was one of the two highest 119901119879 tracks of either


0

2

4

6

8

0 5

minus2

ln120582

CC e

ln 120582NCe

(a) ]120583NC+CC

0 5

0

2

4

6

8

minus2

ln120582

CC e

ln 120582NCe

(b) ]119890CC

0

2

4

6

8

0 5

minus2

minus4

ln120582

CC e

ln 120582NCe

(c) 120591 rarr 119890

0 5

0

2

4

6

8

minus2

minus4

ln120582

CC e

ln 120582NCe

IIIIII VI

VIV

(d) Data

Figure 9 Scatter plot of ln 120582NC119890

versus ln 120582CC119890

for simulated signal and backgrounds (from [10ndash13]) (a)MC ]120583NC events and the few surviving

]120583CC events (b) MC ]

119890CC events (c) simulated 120591minus rarr 119890

minus]119890]120591events (d) data The box at the upper right corner indicates the signal region

and is divided into subboxes for the analysis

charge in the event It was then required that this candidatenot be identified as a muon or as an electron associated withan energy deposition in the ECAL and that 3 lt 119901

120591

119881lt

150GeVcThere was a residual background from ]120583 CC interactions

in which the outgoing 120583 was selected as the ℎminus because

it either decayed in flight or suffered a highly inelasticinteraction in the calorimeters This happened in about 10minus4

of all ]120583CC events These events were rejected by a likelihoodfunction

The study continued with the 120591minus

rarr ℎminusℎ+ℎminus(1198991205870)]120591

decay channel This channel was characterized by the pres-ence of additional constraints due to the internal 3h structureThis searchwas optimized for the ℎminusℎ+ℎminus]120591 decay dominatedby the chain 120591

minusrarr 119886minus

1(1260)]120591 119886

minus

1rarr 1205880(770)120587

minus 1205880 rarr

120587+120587minus Both the candidate selection and the final background

rejectionwere based upon an artificial neural network (ANN)


technique The input variables chosen in order to exploitboth the internal structure and the global kinematics ofthe 3120587 combinations were the 3120587 invariant mass the twopossible 120587+120587minus invariant masses and 120579max and 120579min and themaximum and the minimum opening angles between thethree pions The network was trained on correct and randomcombinations of the 120591 decay products The selection of the 120591daughter candidate as the 3120587 combination with the highestvalue resulted in the correct choice in 73 of the cases

The same hadronic decay channels were searched for inthe LM topologies [10ndash13]

54 Conclusion on ]120583 ]120591 Oscillation The final result of themeasurement was expressed as a frequentist confidenceinterval which accounted for the fact that each 120591minus decaymodeand signal bin may have a different signal to backgroundratio The acceptance region became multidimensional tocontain each of the separatemeasurementsThis computationtook into account the number of observed signal events theexpected background and its uncertainty and the value ofexpected signal events if the oscillation probability was unityFor the ]120583 rarr ]120591 oscillation this last quantity was defined by

119873(]120583 997888rarr ]120591) = 119873obs120583

sdot (

120590120591

120590120583

) sdot Br sdot (120576120591

120576120583

) (4)

where

(i) 119873obs120583

was the observed number of ]120583 CC interactionsfor the given efficiency 120576120583

(ii) 120576120591 and 120576120583 were the detection efficiencies for the 120591minus

signal events and ]120583 CC events respectively The cutsused to select 119873obs

120583and 120576120583 varied from channel to

channel in order to reduce systematic uncertainties inthe ratio 120576120591120576120583 for that channel

(iii) 120590120591120590120583 was the suppression factor of the ]120591 cross-section due to the difference between the 120591 and 120583

masses which for a given ]120583 spectrum and the largeΔ1198982 hypothesis was evaluated to be 048 060 and

082 for the DIS RES and QE processes(iv) Br was the branching ratio for the considered 120591 decay

channel

The overall systematic uncertainty on the backgroundprediction was estimated to be 20 The correspondinguncertainty on119873(]120583 rarr ]120591)was 10The impact of this lattervalue on the final combined results was negligible

The analysis of the full NOMAD data sample gave noevidence for ]120591 appearance The resulting 90 CL upperlimit on the two-generation ]120583 rarr ]120591 oscillation probabilitywas

119875 (]120583 997888rarr ]120591) lt 22 10minus4 (5)

The excluded region in the plane (sin22120579120583120591-Δ1198982) is

shown in Figure 10 together with limits published from otherexperiments [14ndash18] In the two-family oscillation formalism

1

1

10

E531

CCFR

NOMAD

CHORUS

CDHS

103

102

Δm2

(eV2

c4)

120583 rarr 120591

90 CL

sin2 2120579

10minus4 10minus3 10minus2 10minus1

Figure 10 Final exclusion plot in the plane (sin22120579120583120591-Δ1198982) for the

channel ]120583rarr ]120591

this result excludes a region of the ]120583 rarr ]120591 oscillationparameters which limits sin22120579120583120591 at high Δ119898

2 to valuessmaller than 33 10minus4 at 90 CL and Δ119898

2 to values smallerthan 07 eV2c4 at sin22120579120583120591 = 1

The same analysis can be used to set a limit on ]119890 rarr

]120591 oscillation [19] As explained before the beam showed acontamination of ]119890 at a level of 001 compared to ]120583 Thusthe search of ]120591 appearance gave an excluded region at 90CL for the ]119890 rarr ]120591 which limits sin22120579 lt 15 10minus2 at largeΔ1198982 and Δ1198982 lt 59 eV2c4 at sin22120579 = 1 For this channel the

sensitivity was not limited by background but by the availablestatistics Another oscillation channel was also searched for]120583 rarr ]119890 The result is given in [20]

The NOMAD experiment explored the ]120583 rarr ]120591oscillation channel down to probabilitiesmore than one orderof magnitude smaller than limits set by the previous genera-tion of experiments For the first time a purely kinematicalapproach was applied to the detection of ]120591 CC interactionsThis demonstrated that the approach developed into amaturetechnique Unfortunately oscillations were not discoveredwith the NOMAD experiment the neutrino masses foundin subsequent experiments proved to be much too small tocontribute significantly to the missing mass of the Universealthough it is known today that neutrinos account for a partabout as large as the one due to all the stars present in theUniverse

6 Study of Strange Particle Production in]120583

CC Interactions

A number of NOMAD publications dealt with strangenessproduction in neutrino interactions [9 21ndash25] We presentsome of these results


0025

005

0075

01

0125

015

0175

02

0225

025

minus1 minus08 minus06 minus04 minus02 0 02 04

I II

III

V

IV

06 08 1120572

pT

int

(GeV

)

Figure 11 Plot of 119901int119879

versus 120572 identifying the populations ofstrange particles (from [22]) Λ1015840s and Λ

1015840s populate boxes I and IIrespectively The 119870∘

119904sample being symmetric is found in all boxes

except box V Photon conversions populate the small 119901int119879

region

61 Yields of Strange Particles [9] The production of strangeparticles in neutrino interactions provided a testing groundfor the quark-parton and for hadronization models Neutralstrange particles could be reliably identified using the1198810-likesignature of their decays in contrast to most other hadronswhich require particle identification hardware All previousinvestigation of strange particle production by neutrinoscame from bubble chamber experiments which suffered fromlow statistics Most recent references are given in [26ndash28]

Among the 13 106 ]120583 CC events collected the NOMADexperiment observed an unprecedented number of neutralparticle decays appearing as a 119881

0-like vertex in the detec-tor with an excellent reconstruction quality The order ofmagnitude increase in statistics was used to improve ourknowledge of 119870119904 Λ 119870

lowastplusmn Σlowastplusmn Ξminus and Σ0 production in ]120583

CC interactionsThis study allowed a quantitative theoreticalinterpretation of the Λ polarization measurements as will bediscussed later

Since NOMAD was unable to distinguish protons frompions in the momentum range of the analysis the 119881

0

identification procedure relied on the kinematic properties ofthe 1198810 decay The fit method was performed for three decayhypotheses 119870119904 rarr 120587

+120587minus Λ rarr 119901120587

minus and Λ rarr 119901120587+ and

for the hypothesis of a gamma conversion to 119890+119890minusFigure 11 shows the plot 119901int

119879versus 120572 in data events

where 119901int119879

is the transverse component of one of the outgoingcharged tracks with respect to the 1198810 momentum and 120572 =

(119901+

119871minus119901minus

119871)(119901+

119871+119901minus

119871) is the longitudinalmomentumasymmetry

between the positive and negative tracksDifferent regions of the plot correspond to different

populationsThree regions corresponding to119870∘119904Λ andΛ are

clearly visible with the119870∘119904sample being symmetric Identified

1198810 were of two types

(i) uniquely identified 1198810 which populated regions in

which decays of only a single particle type werepresent

(ii) ambiguously identified 1198810 which populated regions

in which decays of different particle types werepresent

It was possible to select subsamples of uniquely identified1198810rsquos with high purity 98 for119870∘

119904 97 for Λ and 90 for Λ

The treatment of ambiguities aimed at selecting a given1198810decay with the highest efficiency and the lowest backgroundcontamination from other 1198810 types MC was used to definethe criteria for the kinematic 1198810 selection and to determinethe purity of the final samples Samples consisting of morethan 90 of uniquely identified 1198810 were selected

The total 1198810 sample contained 15074 identified 119870119904 8987identified Λ and 649 identified Λ representing significantlylarger numbers than in previous experiments performedwithbubble chambersThus the production rate of neutral strangeparticles in ]120583 CC interactions was measured The integralyields per ]120583 CC interactions were the following

(676 plusmn 006) for 119870119904

(504 plusmn 006) for Λ


(6)

The yields of 119870119904 rose steadily with E] and 1198822 reached a

plateau at large 1198762 and fell with increasing Bjorken scalingvariable 119909119861119895 The Λ yield showed a behavior almost indepen-dent of E]119882

2 and 1198762 after a sharp initial rise The Λ yields

were measured for the first time All the plots appear in [9]Furthermore a detailed analysis of kinematic quantities

describing the behavior of neutral strange particles insidethe hadronic jet was performed In particular the followingdistributions were studied

(i) the Feynman-119909 the longitudinal momentum fractionin the hadronic center of mass system 119909119865 = 2119901

lowast

L 119882

(ii) the fraction 119911 = 119864lab(1198810)119864lab (all hadrons) of the

hadronic energy carried away by the neutral strangeparticle in the laboratory system

(iii) the transverse momentum squared 1199012

119879 of a particle

with respect to the hadronic jet direction

The 119909119865 distribution indicated that Λ1015840s were producedmainly in the target fragmentation region (119909119865 lt 0) while 119870119904were peaked in the central region with an asymmetry in theforward directionΛ1015840s were produced in the central 119909119865 region(minus05 lt 119909119865 lt 05)

The 119911 distributions showed a turnover at small values of119911 for Λ but not for 119870∘

119904and Λ which showed a maximum at

119911 rarr 0


The 1199012119879distributions showed an exponential behavior of

the form exp(minus1198611199012119879) with a slope parameter B in the region

0 lt 1199012

119879lt 05GeV2c2 around 57 for119870∘

119904 44 forΛ and 39 for

Λ

62 Measurement of the Λ Polarization [23 24] The study ofΛ polarization relied on an efficient and robust Λ hyperonidentification algorithm and a high statistics sample Λ

hyperons were identified via their decay Λ rarr 119901120587minus As

discussed above the identification procedure optimized boththe selection efficiency and the purity of the final sample Itrequired the presence of an identified muon at the primaryvertex both primary and 119881

0 vertices in the fiducial volumeand a reconstructed energy 119864] lt 450GeV Samples of8987Λ1015840s and 649Λ1015840s were selected with global efficiencies of(164 plusmn 01) and (186 plusmn 05) corresponding to purities of(959 plusmn 01) and (897 plusmn 07) respectively

The Λ polarization was measured by the asymmetry inthe angular distribution of the proton In theΛ rest frame thedecay protons are distributed as follows

1

119873

d119873119889Ω

= (

1

4120587

) (1 + 120572ΛP sdot k) (7)

where P is the Λ polarization vector 120572Λ = (0642 plusmn 0013)

is the decay asymmetry parameter and k is the unit vectoralong the decay direction of the positive track

Dependences of the polarization on 119909119865 1198822 1198762 and 119901119879

were studied together with the target nucleon type (neutronsor protons) This is discussed in [23 24] Negative polariza-tions along the 119882-boson direction (119875119909) and in the directionorthogonal to the production plane (119875119910) were foundThis wasthe first time that a neutrino experiment observed a nonzerotransverse polarization 119875119910 The longitudinal polarizationshowed an enhancement in the target fragmentation region(119909119865 lt 0) 119875119909 = minus021 plusmn 004(stat) plusmn 002(sys) while inthe current fragmentation region (119909119865 gt 0) the longitudinalpolarization was found to be 119875119909 = minus009 plusmn 006(stat) plusmn003(sys) A similar dependence on 119909119865 was observed for thetransverse polarization

There was an enhancement of the longitudinal polar-ization in both low 119882

2 (lt15 GeV2) and low 1198762 (lt5GeV2)

regions Both 119875119909 and 119875119910 strongly depend on the 119901119879 of theΛ with respect to the hadronic jet direction in qualitativeagreement with the results of unpolarized hadron-hadronmeasurements

The longitudinal polarization in the proton-like targetsamplewas found to be negative and enhanced in comparisonwith the total event sample This could be interpreted asbeing due to Λ

1015840s coming from the decay of Σlowast+ and otherheavier baryons The measured longitudinal polarization inthe neutron-like target sample was also negative and probablymore directly related to the polarized strange content ofthe nucleon The transverse polarization was more evidentin the neutron-like sample where most Λ1015840s were producedpromptly

The Λ polarization was also measured The results aregiven in [25]

7 Dimuon Charm Production

The most recent NOMAD publication [29] concerns thedimuon charm production in neutrino interactions

The process of charm dimuon production stems from the]120583 CC production of a charm quark which semileptonicallydecays into a final-state secondary muon with its electriccharge opposite to that of the muon from the leptonic CCvertex The DIS production of charm quarks involves thescattering off strange and nonstrange quark contents of thenucleonHowever the contributions from119906- and119889-quarks aresuppressed by the small quark-mixing matrix elements

The signal consists in two muons of opposite sign com-ing from a common vertex A measurement of the cross-section for charm dimuon production in neutrino DIS offnucleons provides the most direct and clean probe of s thestrange quark sea content of the nucleon Traditionally charmdimuon production in neutrino interactions was measuredin massive calorimeters in order to obtain a sizable numberof events [30ndash37] Because of its lowest energy threshold119864] sim 6GeV and its high resolution NOMAD reached anew level of precision in this measurement Furthermorethe neutrino spectrum in NOMAD was well suited to studycharm production close to the charm threshold providingenhanced sensitivity to the charm production parameters

71 Dimuon Selection The FCAL was used as the interactiontarget to profit from its large mass The selection of theevents required a deposition of energy in the FCAL of morethan 35mip together with the 1198818 veto and two muonsaccurately analysed in the DC region and well recognizedin the muon system Such a signal selected opposite signdimuons and like-sign dimuons which gave a direct estimateof the background

The total hadronic energy was calculated with both theenergy measured in the FCAL and the energies measured inthe DCrsquos with the proper corrections included

The selection was based on a primary muon (the highestenergy one) of negative charge thus suppressing the contri-bution of antineutrino interactions

72 Charm Dimuon Results The charm dimuon events weredetermined from the opposite sign dimuon signal measuredin the data after subtracting the background coming frommuonic decays of hadrons in the hadronic shower

119873120583120583119888 = 119873120583120583+ minus 119873120583120583+119887119892

(8)

The background was evaluated from the 120583minus120583minus events

corrected by a scale factor extracted from the MC Thebackground estimate was checked using the data themselvesconsisting in mesons of both charges detected in the DCrsquos

After all cuts the analysis retained 20479 opposite signdimuons of which 75 were genuine charm signals Thisrepresented the highest available statistics and the qualityof the reconstruction allowed to lower significantly theenergy threshold on the second muon down to 3GeV Thisfeature gave an additional sensitivity to evaluate the charmproduction parameters


10

0

2

4

6

8

NOMADCHORUS ModelCCFR

102

E (GeV)

times10minus3

E53A+ E53B

120590120583120583

120590CC

Figure 12 Ratio between charmdimuon cross-section and inclusive]120583CC cross-section from NOMAD (from [29]) Previous measure-

ments are also shown

The analysis measured the ratio of the charm dimuoncross-section to the inclusive CC cross-section as a functionof the kinematic variables

119877120583120583 =

120590120583120583

120590CCcong

119873120583120583119888

119873CC (9)

The final result for 119877120583120583 shown as a function of theneutrino energy is given in Figure 12

By integrating this result the average dimuon productionin NOMAD was evaluated Over the NOMAD flux for 1198762 ge1GeV2c2 the result was (515 plusmn 005 plusmn 007) 10minus3 The firstuncertainty is statistical and the second systematic

Fitting 119877120583120583 allowed to extract the charm productionparameters including the mass of the charm quark 119898119888 theeffective semileptonic branching ratio 119861120583 and the strange seasuppression factor

The running mass of the charm quark evaluated in the119872119878 scheme was found to be

119898119888 = (1159 plusmn 0075) GeVc2 (10)

The semileptonic branching ratio was parameterized as afunction of the neutrino energy

119861120583 (119864]) =(0097 plusmn 0003)

1 + (67 plusmn 18Gev) 119864] (11)

The strange quark sea suppression factor was found to be

120581119904 = 0591 plusmn 0019 at 1198762 = 20GeV2c2 (12)

These results represent the most precise measurementsfrom neutrino data

8 Other Physics Topics

The NOMAD experiment conducted several other mea-surements inclusive production of resonances [38] Bose-Einstein correlations in ]120583 CC interactions [39] ]120583-nucleon

cross-section off an isoscalar target [40] study of quasielasticevents [41] coherent neutral pion production [42] singlephoton production [43] and backward going particles [44]Also some more exotic ideas were tested search for a newgauge boson [45] search for eV scalar penetrating particles[46] and search for heavy neutrinos [47] We will developsome of these topics

81 Inclusive Production of Various Resonances [38]NOMAD measured the production yield of meson resonan-ces 1205880(770)1198910(980) and1198912(1270) In particular the1198910mesonwas observed for the first time in neutrino interactions Allcombinations of tracks with momenta larger than 01 GeVcoriginating at the primary vertex and not identified aselectrons or muons were used for the reconstruction of theresonance candidates All used tracks were assigned the pionmass

The distribution of the 120587+120587minus invariant mass showed anenhancement at the1205880masswhichwas not present in the like-sign distributionsWhen a cut 119909119865 gt 06was applied to reducethe combinatorial background clear peaks at the f 0 and f 2masses were visible The result is shown in Figure 13 Theresonance signal was determined by fitting the invariantmassdistribution to a sum of relativistic Breit-Wigner functionswith combinatorial background added

The average 1205880(770) multiplicity measured for ]120583CC

interactions was found to be (0195 plusmn 0007 plusmn 0019) for119882 gt

2GeV It was found to be the same in ]120583CC interactionsNOMAD also measured the production of strange res-

onances and heavier hyperons This study was of interest totune the LUND model parameters and for the theoreticalinterpretation of Λ and Λ polarization measurements Thiswas essential because Λ1015840s originating from the decays of ΣlowastΣ0 and Ξ inherit a polarization from their parent particles

different from that of a directly produced ΛTo construct the samples neutral strange particles were

combined with all possible charged tracks of appropriate signemerging from the primary vertex except those identifiedas muons or electrons Combinations of Λ with 120574 were alsostudied where photons were identified as conversions in thedetector fiducial volume

The 119870lowastplusmn was recognized in the 119870119904120587

plusmn invariant massdistributions and the Σlowastplusmn appeared in theΛ120587plusmn combinationsStill in the Λ120587

minus there was evidence of Ξminus production Ξ0showed in the invariant mass distribution of Λ120574 combina-tions All these plots appear in [9 38]

Corrected fractions of observed 1198700

119904and Λ decays that

originate from the decays of strange resonances and heavyhyperons were found to be (155 plusmn 09) (87 plusmn 07) (58 plusmn11) (26 plusmn 08) (73 plusmn 24) and (19 plusmn 17) for thechannels 119870lowast+ rarr 119870

0

119904120587+ 119870lowastminus rarr 119870

0

119904120587minus Σlowast+ rarr Λ120587

+Σlowastminus

rarr Λ120587minus Σ0 rarr Λ120574 and Ξminus rarr Λ120587

minus respectively

82 Study of Quasielastic Events [41] With its high granular-ity target NOMADwas well suited to study the ]120583 quasielasticscattering reaction (QEL) ]120583119899 rarr 120583

minus119901The data sample used

in this analysis consisted of 751000 ]120583 CC events in a reducedfiducial volume the average energy of the incoming ]120583 being


0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Com

bina

tions

10

MeV

M(120587+120587minus) (GeVc)05 06 07 08 09 1 11 12 13 14 15

Figure 13 Distribution of the 120587+120587minus invariant mass showing evi-

dences for 1205880(770) 1198910(980) and 119891

2(1270) production after back-

ground suppression

25GeV Previous data came mostly from bubble chamberexperiments and suffered from small statistics Moreoverlarge systematic uncertainties came from the poor knowledgeof the incoming neutrino flux For some previous results see[48ndash50]

The event selection retained two tracks originating fromthe primary vertex one of them identified as a muon Themuon track was easily reconstructed however the protonwasmore difficult to measure Sometimes the proton could notbe reconstructed because its momentum was too low wellbelow 1GeVc or its angle too large above 60 degrees Forpositive tracks such conditions meant that they made almostimmediately a 119880-turn due to the magnetic field Positiveparticles were deviated upwards so that their trajectoriesended almost parallel to the DC planes It was crucial tochoose a region in the detector with a stable reconstructionefficiency This was achieved by selecting QEL events whereprotons were emitted in the lower hemisphere of the detectorConsequently a cut selected muons in the upper hemisphere

Moreover the tracks were in the 11205732 region of ionizationloss and they crossed the drift cells at very large angles wherethe spatial resolution of theDCwas considerablyworse Someof these effects were difficult to parameterize and simulateAlso the proton could lose part of its energy in an intranuclearcascade In the analysis it was important to disentangle thereconstruction efficiency effects from the effects induced byintranuclear cascade which changed the proton kinematics

Using only 2-track events did not alleviate the problemof a large systematic uncertainty coming from insufficientunderstanding of nuclear effects So the 1-track sample muononly was also used For these events the muon momentum

and direction were the sole measurements and conservationlaws were used to compute other kinematical quantities like119864] and 119876

2 The expected ratio between 1-track and 2-trackevents for QEL was calculated to be 54ndash46

In total the samples used in the analysis consisted of 14021neutrino and 2237 antineutrino events No precise knowledgeof the integrated neutrino flux existed so the QEL cross-section was normalized to the total DIS ]120583 CC cross-sectionor to inverse muon decay

The flux-averagedQEL cross-sectionwasmeasured in theneutrino energy region 3ndash100GeV The result for ]120583 was

120590QEL = (092 plusmn 002 (stat) plusmn 006 (syst)) sdot 10minus38 cm2 (13)

and for the antineutrino case


The cross-section depends on the axial form factor119865119860(1198762) of the nucleon which is parameterized with only

one adjustable parameter the so-called axial mass 119872119860 Thisparameter describes the internal structure of the nucleonand should be the same for both neutrino and antineutrinomeasurements The conventional representation uses theform119865119860(119876

2)=119865119860(0)(1+119876

21198722119860)minus2 where119865119860(0) =minus12695plusmn

00029 comes from neutron 120573-decayWith the neutrino data the result was 119872119860 = 105 plusmn

002(stat) plusmn 006(syst)GeV and with the antineutrino 119872119860 =

106 plusmn 007(stat) plusmn 012(syst)GeV

83 Backward Going Particles [44] In high energy inter-actions off nuclei there are particles emitted backwardswith respect to the beam direction which have energiesnot allowed by the kinematics of collisions on a free andstationary nucleon Backward going protons are commonlyobservedwhile in absence of nuclear effects their productionis forbidden Likewise high energy mesons are detected atmomenta above the kinematical limit These effects havebeen used to investigate nuclear structure Two categories ofmodels are proposed to explain the origin of these particles

(i) In the intranuclear cascade models the production ofparticles in the kinematically forbidden region can beseen as the result of multiple scattering and of interac-tions of secondary hadrons produced in the primary]-nucleon collision while they propagate through thenucleus One observes that the cascade is restrictedto slow particles only while the fast ones do notreinteract inside the nucleus The currently acceptedexplanation for this effect is the ldquoformation zonerdquoconcept This is the distance from the productionpoint which is required for the secondary hadronsto be ldquoformedrdquo and be able to interact as physicalhadronic states An advantage of neutrino-inducedinteractions with respect to hadronic processes is thefact that the projectile interacts only once

(ii) In the correlated nucleonquarkmodels the backwardparticles are produced in the collisions off structureswith mass larger than the mass of the nucleon These


structures are formed under the action of the short-range part of the nuclear force they represent theeffects of gathering two or more nucleons in smallvolumes

The full NOMAD sample of ]120583 CC events having amuon momentum of at least 3GeVc used in this analysisamounted to 944000 events Only tracks attached to theprimary vertex and having at least 8DC hits were used inthe search for backward particles The separation betweenbackward protons and pions was done on plots showinglength versus momentum tracks Protons were only visiblein the plot of positive tracks having a relatively small lengthWith the help ofMC simulations corrections were applied forreconstruction stopping and identification efficiencies Thecontamination of pions in the sample of identified protonsamounted to 8 above 250MeVc

The average number of backward protons per event wasfound to be around 5 The rates were studied as a functionof the hadronic energy 119864had and of119876

2 A decrease of the yieldwith increasing 119864had and 119876

2 was observedThe slope parameter 119861 of the invariant cross-section

parameterized as exp(minus1198611199012) has been measured and foundto be consistent with previous ]-nucleus and hadron-nucleusexperiments 119861was found not to depend on 119864had and119876

2 overa wide range of values Its value was 119861 sim 10 c2GeV2 Thiswas in agreement with ldquonuclear scalingrdquo previously observedin hadronic experiments

The backward proton rate measured in the NOMADtarget (mainly carbon) has been compared with the valuesobtained on different nuclei While the A dependence forneutrino scattering on heavy nuclei is consistent with thatof hadron experiments and can be parameterized as 119860120572 with120572 = 068 the NOMAD result does not fit this dependenceThe119860 dependence of backward pions was found to be steeperthan that of backward protons

The backward proton data was compared with the predic-tions of reinteractions and short-range modelsThe observedenergy dependence is consistent with the ldquoformation zonerdquomechanism The correlation between the multiplicity ofslow tracks and backward protons indicates the effects ofreinteractions

84 Search for Heavy Neutrinos [47] The existence of sterileneutrinos has been advocated to explain several experimentalanomalies Many models that attempt to unify the presentlyknown interactions into a single gauge scheme predict suchheavy neutrinos which are decoupled from119882 and 119885 bosonsThey are also predicted in extended electroweak and see-sawmodels trying to solve the problem of baryo- or leptogenesisin the Universe Stringent experimental limits were publishedon mixings with ]119890 and ]120583 [51 52] NOMAD allowed a test ofa neutral heavy lepton (]4) dominantly associated with the ]120591via the mixing term 119880

2

1205914

In this search the potential source of ]4 was119863119904 producedat the proton target and decaying via 119863119904 rarr 120591]4 As aconsequence the search was limited to ]4 masses smallerthan 190MeVc2 If ]4 was a long-lived particle its flux

would penetrate the downstream shielding without signifi-cant attenuation Formasses below the1205870mass the dominantheavy neutrino visible decay in the detector would be ]4 rarr]120591119890+119890minus with a rate given by the weak interaction diagrams

It would appear as an excess of isolated 119890+119890minus pairs above

those expected from standard interactionsThe experimentalsignature of these events was clean and they could be selectedwith small background due to the excellent capability forprecise measurement of the 119890+119890minus pair direction in NOMAD

With the above hypotheses the ]4 flux and the conse-quent 119890+119890minus spectrum were calculated The search used thefull data sample The strategy consisted of identifying 119890

+119890minus

candidates by reconstructing isolated low invariant mass119890+119890minus pairs in the DC target that were accompanied by no

other activity in the detector At least one of the two trackshad to be identified as an electron in the TRD no 120574 inthe ECAL and an HCAL energy smaller than 400MeVand 119890

+119890minus invariant mass smaller than 95MeVc2 Only 207

events passed the criteria A collinearity variable was usedto select events with a small angle between the averageneutrino beam direction and the total momentum of thereconstructed 119890

+119890minus pair A cut on this angle allowed a very

effective background suppression Checks of the procedurewere done using a ]120583 CC data sample with 119890

+119890minus pairs from

photons converted in the DC target at a large distance fromthe primary vertex MC simulations were used to correctthe data for acceptance losses experimental resolution andreconstruction efficiencies Checks were performed in orderto verify the reliability of the simulation using reconstructed12058701015840s with one photon converted in the DCThe largest contribution to the background was expected

from neutrino interactions yielding a single 1205870 with little

hadronic activity in the final state A blind analysis resultedin one event passing the selection criteria consistent with theexpected background and hence no evidence for isosingletneutrino decays was found This allowed a 90 CL upperlimit on the corresponding mixing amplitude 119880

2

1205914in the

(1198984 1198802

1205914) plane The limit reached 10minus3 for a mass 1198984 of

140MeVc2

9 Conclusion

The NOMAD experiment did not discover neutrino oscilla-tionsWe know now that the masses of the neutrino states aremuch smaller than the 1 eV level originally hoped for in theexperiment This means that cosmological neutrinos cannotcontribute predominantly to the intriguing problem of themissing mass found in the Universe Nevertheless NOMADput limits on the ]120583 rarr ]120591 oscillation channel that are twoorders of magnitude better than previous published limitsand this result remains 15 years later

Furthermore because of its high spatial resolution andidentification capabilities the experiment contributed toa deeper understanding of neutrino properties measuringmany other standard processes and testing several theoreticalsuggestions The list of publications gives a summary of allthe topics which have been studied by the experiment In thispaper we have shown a selection of the obtained results


Conflict of Interests

The author declares that there is no conflict of interestsregarding the publication of this paper

References

[1] P Astier D Autiero A Baldisseri et al ldquoPrediction of neutrinofluxes in the NOMAD experimentrdquo Nuclear Instruments andMethods in Physics Research A vol 515 no 3 pp 800ndash828 2003

[2] M Anfreville P Astier M Authier et al ldquoThe drift chambersof the NOMAD experimentrdquo Nuclear Instruments and Methodsin Physics Research A vol 481 no 1ndash3 pp 339ndash364 2002

[3] J Altegoer M Anfreville C Angelini et al ldquoThe NOMADexperiment at theCERNSPSrdquoNuclear Instruments andMethodsin Physics Research A vol 404 no 1 pp 96ndash128 1998

[4] G Bassompiere M Bermond M Berthet et al ldquoA large areatransition radiation detector for the NOMAD experimentrdquoNuclear Instruments andMethods in Physics ResearchA vol 403pp 363ndash382 1998

[5] G Bassompiere S Bunyatov T Fazio et al ldquoPerformance oftheNOMAD transition radiation detectorrdquoNuclear Instrumentsand Methods in Physics Research A vol 411 pp 63ndash74 1998

[6] D Autiero M Baldo-Ceolin G Barichello et al ldquoThe elec-tromagnetic calorimeter of the NOMAD experimentrdquo NuclearInstruments and Methods in Physics Research A vol 373 pp358ndash373 1996

[7] D Autiero M Baldo-Ceolin F Bobisut et al ldquoA study of thetransverse fluctuations of hadronic showers in the NOMADelectromagnetic calorimeterrdquoNuclear Instruments andMethodsin Physics Research A vol 411 no 2-3 pp 285ndash303 1998

[8] J Altegoer J Andrle S Boyd et al ldquoThe trigger system ofthe NOMAD experimentrdquo Nuclear Instruments and Methods inPhysics Research A vol 428 no 2-3 pp 299ndash316 1999

[9] P Astier D Autiero A Baldisseri et al ldquoA study of strangeparticle production in ]

120583charged current interactions in the

NOMAD experimentrdquo Nuclear Physics B vol 621 no 1-2 pp3ndash34 2002

[10] J Altegoer C Angelini P Astier et al ldquoA search for V120583rarr V120591

oscillations using the NOMAD detectorrdquo Physics Letters B vol431 no 1-2 pp 219ndash236 1998

[11] P Astier D Autiero A Baldisseri et al ldquoAmore sensitive searchfor V120583rarr V120591oscillations inNOMADrdquoPhysics Letters B vol 453

no 2-3 pp 169ndash186 1999[12] P Astier D Autiero A Baldisseri et al ldquoUpdated results from

the V120591appearance search in NOMADrdquo Physics Letters B vol

483 no 4 pp 387ndash404 2000[13] P Astier D Autiero A Baldisseri et al ldquoFinal NOMAD results

on V120583rarr V120591and V

119890rarr V120591oscillations including a new search

for V120591appearance using hadronic 120591 decaysrdquo Nuclear Physics B

vol 611 no 1ndash3 pp 3ndash39 2001[14] T Kondo N Ushida S Tasaka et al ldquoLimits to V

120583 V119890rarr V120591

oscillations and V120583 V119890rarr 120591minus direct couplingrdquo Physical Review

Letters vol 57 no 23 pp 2897ndash2900 1986[15] E Eskut A Kayis G Onengut et al ldquoA search for V

120583rarr V120591

oscillationrdquo Physics Letters B vol 424 no 1-2 pp 202ndash212 1998[16] M Gruwe C Mommaert P Vilain et al ldquoSearch for V

120583rarr V120591

oscillationrdquo Physics Letters B vol 309 no 3-4 pp 463ndash4681993

[17] K S McFarland G J Feldman C Guyot et al ldquoA search for V120583

oscillations in the 9987791198982 range 03ndash90 eV2rdquo Physics Letters B vol134 no 3-4 pp 281ndash286 1984

[18] F Dydak T Kondo S Tasaka et al ldquoLimits to V120583 V119890

rarr V120591


Letters vol 57 no 23 pp 2897ndash2900 1986[19] P Astier D Autiero A Baldisseri et al ldquoLimit on V

119890rarr V120591

oscillations from the NOMAD experimentrdquo Physics Letters Bvol 471 no 4 pp 406ndash410 2000

[20] P Astier D Autiero A Baldisseri et al ldquoSearch for V120583

rarr V119890

oscillations in the NOMAD experimentrdquo Physics Letters B vol570 no 1-2 pp 19ndash31 2003

[21] D Naumov A Chukanov E Naumova et al ldquoA study of strangeparticles produced in neutrino neutral current interactions inthe NOMAD experimentrdquo Nuclear Physics B vol 700 no 1ndash3pp 51ndash68 2004

[22] A Chukanov D Naumov B Popov et al ldquoProduction prop-erties of 119870lowast(892)plusmn vector mesons and their spin alignment asmeasured in the NOMAD experimentrdquo The European PhysicalJournal C vol 46 no 1 pp 69ndash79 2006

[23] P Astier D Autiero A Baldisseri et al ldquoMeasurement of the 120582polarization in ]

120583charged current interactions in the NOMAD

experimentrdquoNuclear Physics B vol 588 no 1-2 pp 3ndash36 2000[24] B A Popov ldquoMeasurement of the Λ hyperon polarization in

]120583charged current interactions in the NOMAD experimentrdquo

Nuclear Physics A vol 692 no 1-2 pp 73ndash80 2001[25] P Astier D Autiero A Baldisseri et al ldquoMeasurement of the Λ

polarization in ]120583charged current interactions in the NOMAD

experimentrdquo Nuclear Physics B vol 605 no 1ndash3 pp 3ndash14 2001[26] S Willocq P Marage M Aderholz et al ldquoNeutral strange

particle production in antineutrino-neon charged current inter-actionsrdquo Zeitschrift fur Physik C vol 53 no 2 pp 207ndash217 1992

[27] G T Jones RW L Jones BW Kennedy et al ldquoNeutral strangeparticle production in neutrino and antineutrino charged cur-rent interactions on protonsrdquoZeitschrift fur Physik C vol 57 no2 pp 197ndash209 1993

[28] DDeProsperoMKalelkarMAderholz et al ldquoNeutral strangeparticle production in neutrino and antineutrino charged-current interactions on neonrdquo Physical Review D vol 50 no11 pp 6691ndash6703 1994

[29] O Samoylov R Petti P Astier et al ldquoSearch for eV (pseudo)scalar penetrating particles in the SPS neutrino beamrdquo PhysicsLetters B vol 479 no 4 pp 371ndash380 2000

[30] G P Zeller K S McFarland T Adams et al ldquoPrecisedetermination of electroweak parameters in neutrino-nucleonscatteringrdquo Physical Review Letters vol 88 no 9 article 0918024 pages 2002

[31] H Abramowicz J G H de Groot J Knobloch et al ldquoExper-imental study of opposite-sign dimuons produced in neutrinoand antineutrino interactionsrdquo Zeitschrift fur Physik C vol 15no 1 pp 19ndash31 1982

[32] P Vilain G Wilquet R Beyer et al ldquoLeading-order QCDanalysis of neutrino-induced dimuon eventsrdquo The EuropeanPhysical Journal C vol 11 no 1 pp 19ndash34 1999

[33] P Astier D Autiero A Baldisseri et al ldquoNeutrino productionof opposite sign dimuons in the NOMAD experimentrdquo PhysicsLetters B vol 486 no 1-2 pp 35ndash48 2000

[34] A O Bazarko C G Arroyo K T Bachmann et al ldquoDetermi-nation of the strange quark content of the nucleon from a next-to-leading-order QCD analysis of neutrino charm productionrdquoZeitschrift fur Physik C vol 65 no 2 pp 189ndash198 1995


[35] D Mason P Spentzouris J Conrad et al ldquoMeasurement ofthe nucleon strange-antistrange asymmetry at next-to-leadingorder in QCD from NuTeV dimuon datardquo Physical ReviewLetters vol 99 no 19 Article ID 192001 4 pages 2007

[36] A Kayis-Topaksu R Tsenov P Annis et al ldquoLeading orderanalysis of neutrino induced dimuon events in the CHORUSexperimentrdquo Nuclear Physics B vol 798 no 1-2 pp 1ndash16 2008

[37] N Ushida T Kondob S Tasaka et al ldquoCross sections forneutrino production of charmed particlesrdquo Physics Letters Bvol 206 no 2 pp 375ndash379 1998

[38] P Astier D Autiero A Baldisseri et al ldquoInclusive productionof 1205880(770) f

0(980) and f

2(1270) mesons in ]

120583charged current

interactionsrdquo Nuclear Physics B vol 601 no 1-2 pp 3ndash23 2001[39] P Astier D Autiero A Baldisseri et al ldquoBosendashEinstein corre-

lations in charged current muonndashneutrino interactions in theNOMAD experiment at CERNrdquoNuclear Physics B vol 686 pp3ndash28 2004

[40] Q KWu S RMishra A Godley et al ldquoA precisemeasurementof the muon neutrino-nucleon inclusive charged current crosssection off an isoscalar target in the energy range 25 lt 119864V lt 40

GeV by NOMADrdquo Physics Letters B vol 660 no 1-2 pp 19ndash252008

[41] V Lyubushkin B Popov J J Kim et al ldquoA study of quasi-elasticmuon neutrino and antineutrino scattering in the NOMADexperimentrdquoThe European Physical Journal C vol 63 no 3 pp355ndash381 2009

[42] C T Kullenberg S R Mishras M B Seaton et al ldquoAmeasurement of coherent neutral pion production in neutrinoneutral current interactions in the NOMAD experimentrdquoPhysics Letters B vol 682 no 2 pp 177ndash184 2009

[43] C T Kullenberg G Bassompierre JM Gaillard et al ldquoAsearch for single photon events in neutrino interactionsrdquoPhysicsLetters vol B706 no 4-5 pp 268ndash275 2012

[44] P Astier D Autiero A Baldisseri et al ldquoA study of backwardgoing 119901 and 120587 in the V

120583119862119862 interactions with the NOMAD

detectorrdquo Nuclear Physics B vol 609 no 3 pp 255ndash279 2001[45] J Altegoer P Astier D Autiero et al ldquoSearch for a new gauge

boson in1205870 decaysrdquoPhysics Letters B vol 428 pp 197ndash205 1998[46] P Astier D Autiero A Baldisseri et al ldquoSearch for eV

(pseudo)scalar penetrating particles in the SPS neutrino beamrdquoPhysics Letters B vol 479 no 4 pp 371ndash380 2000

[47] P Astier D Autiero A Baldisseri et al ldquoSearch for heavyneutrinos mixing with tau neutrinosrdquo Physics Letters vol B506no 1-2 pp 27ndash38 2001

[48] S V Belikov A P Bygorsky L A Klimenko et al ldquoQuasi-elasticnutrino and antineutrino scattering total cross sections axialform factorrdquo Zeitschrift fur Physik A vol 320 no 4 pp 625ndash633 1985

[49] H J Grabosch et al Soviet Journal ofNuclear Physics vol 47 p1032 1988

[50] J Brunner et al ldquoZeitschrift fur Physik Ardquo vol 45 p 551 1990[51] G Bernardi G Carugno J Chauveau et al ldquoSearch for heavy

neutrino decayrdquo Physics Letters B vol 166 no 4 pp 479ndash4831986

[52] G Bernardi G Carugno J Chauveau et al ldquoFurther limits onheavy neutrino couplingsrdquo Physics Letters B vol 203 no 3 pp332ndash334 1988

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


FluidsJournal of

Atomic and Molecular Physics

Journal of



Advances in Condensed Matter Physics

OpticsInternational Journal of



AstronomyAdvances in

International Journal of


Superconductivity


Statistical MechanicsInternational Journal of


GravityJournal of


AstrophysicsJournal of


Physics Research International


Solid State PhysicsJournal of

Computational Methods in Physics

Journal of



Soft MatterJournal of

Hindawi Publishing Corporationhttpwwwhindawicom

AerodynamicsJournal of

Volume 2014


PhotonicsJournal of


Journal of

Biophysics


ThermodynamicsJournal of


and low backgrounds the NOMAD detector had to fulfill thefollowing criteria

(i) measurement of the momenta of charged particleswith good precision and

(ii) identification and measurement of electrons pho-tons and muons

The excellent performances of the NOMAD detectorfulfilled these goals

In addition to searching for neutrino oscillations thelarge sample of well-reconstructed data collectedwith a targethaving the density of a hydrogen bubble chamber permittedto study many other processes involving neutrinos

The Monte Carlo (MC) simulation used throughout thisstudy was based on modified versions of LEPTO 61 andJETSET 74 generators for neutrino interactions and on aGEANT-based program for the detector response

2 The Beam

The NOMAD detector was located at the CERN west areaneutrino facility (WANF) and was exposed to the SPSwide-band neutrino beam consisting predominantly of ]120583rsquosThe beam line has been operating for 20 years and wasreoptimized in 1992-1993 for the NOMAD and CHORUSexperiments Details of operations are given in [1]

The neutrinos were predominantly produced from thedecays in flight of the secondary 120587 and119870mesons originatingfrom the 450GeV protons impinging on a beryllium targetThe SPS cycle was repeated every 144 s The protons wereextracted from the SPS in two 4ms long spills separated by26 s with a 20 s ldquoflat toprdquoThe beam line operated with recordintensities up to 18 1013 protons in each of the two spillsDuring the four years of data taking 1995ndash1998 NOMADcollected a total of 22 1019 protons incident on the target

The target station consisted of 11 beryllium rods sepa-rated by 9 cm gaps Each rod was 10 cm long and 3mm indiameter positioned longitudinally along the proton lineThe secondary pions and kaons were focused by a pair ofcoaxial magnetic lenses called the horn and the reflectorIn such a system charged particles were deflected by thetoroidal field between two coaxial conductors carrying equaland opposite currents so that the focusing of particles ofone sign implied defocusing particles of the opposite sign Inorder to harden the neutrino spectrum the horn and reflectorwere displaced 20m and 90m from the target respectivelyThe higher neutrino energy increased the sensitivity of theexperiment to charged current ]120591 interactions which have anenergy threshold of 35 GeV The sections between the hornand the reflector and between the reflector and the decaytunnel were enclosed in helium tubes of 80 cm diameter anda total length of about 60m in order to reduce the absorptionof secondary particles Collimators reduced the antineutrinoscontamination by intercepting the defocused secondaries

The mesons were allowed to decay in a 290m longvacuum tunnel Shieldingmade from iron and earth followedIts usewas to range outmuons and absorb hadrons A toroidalmagnet operated at 3 kA located at the entrance of the iron

shielding deflected muons which would pass outside theshielding The NOMAD detector was located 835m from thetarget The average distance between the meson decay pointsand NOMAD was 620m

A neutrino beam monitoring system based on the detec-tion of muon yields at several depths into the iron shield wasbuilt Silicon detectors provided an absolute flux measure-ment An independent measurement of the flux was given bythe number of protons incident on the target estimated froma pair of beam current transformers (BCT) upstream of thetarget

A detailed GEANT simulation of the beam line pre-dicted the neutrino energy and radial position distribu-tions Figure 1 shows the neutrino flux for 109 protonson target The Monte Carlo simulation predicted the rela-tive abundance of neutrino species ]120583 anti]120583 ]119890 anti]119890 =100 0061 00094 00024 with average energies of 235 192371 and 313 GeV respectively

Since the search consisted in observing ]120591 interactions itwas essential to calculate the intrinsic ]120591 component in thebeam This component came from the prompt reactions

119901 + 119873 997888rarr 119863119904 + 119883

followed by 119863119904 997888rarr 120591 + ]120591 120591 997888rarr ]120591 + 119883

(1)

The relative number of ]120591 produced from the abovereactions and interacting via the CC channel in the fiducialvolume of NOMAD was estimated to be 5 10minus6 with respectto ]120583CC interactions The resulting intrinsic ]120591 signal wasmuch less than one event in the total duration of theNOMADexperiment

3 The Detector

The detector is shown schematically in Figure 2 It consistedof a number of subdetectors most of which were located in alarge dipole magnet having an inner volume of 75m alongthe beam axis and 35 times 35m2 in transverse dimensionsThecoordinate system adopted for NOMAD had the 119909-axis intothe plane of the figure the 119910-axis directed up towards thetop of the detector and the 119911-axis horizontal approximatelyalong the direction of the neutrino beam The beam linepointed upwards at an angle of 24∘ with the 119911-axis Themagnetic field was along the 119909-axis and had a value of04 T

Moving downstream along the beam direction camea veto counter a front calorimeter a large active targetconsisting of drift chambers a transition radiation detec-tor a preshower an electromagnetic calorimeter a hadroncalorimeter and an iron filter consisting in the return-yokeof the magnet followed by a set of large drift chambersused for muon identification Upstream and downstreamof the transition radiation detector two large hodoscopesof scintillators provided a fast trigger The key featuresof each subdetector are given below Overall the detectorreconstructed the events kinematics with great precision andidentified electrons muons and photons


(a) (b)

(c) (d)








chambersMuon

beamNeutrino

calorimeterHadronic

modulesTRD

Dipole magnet


calorimeterFront

Veto planes

x

y

z

1m

otimes

otimes B = 04T

V8

Preshower












120590119901

119901

sim

005

radic (119871)

+

0008pradic(1198715)

(2)



Entr

ies

0

500

1000

1500

2000

2500

3000

3500

4000

4500skins

Kevlar

Gas

gap

Hon

eyco

mb

Hon

eyco

mb

Hon

eyco

mb

Hon

eyco

mb

Gas

gap

Gas

gap
















45

40

35

30

25

20

15

10

5

00 5 10 15 20 25

(au

)

10GeV pions

10GeV electrons

Energy (keV)






























































0

001

002

003

004

005

006

007

042 044 046 048 05 052 054 056 058

(au

)

MK (GeVc2)

120590 = 109 (MeVc2)MC mean = 4972

120590 = 112 (MeVc2)Data mean = 4979




0

20

40

60

80

100

120

140

160

180 Entries

Const

Mpi0

Std

BkgConst

BkgMean

BkgRMS

3211

106181

1175 plusmn 8175



5197 plusmn 9839




1205942ndf












Oscillation





minus]119890]120591 ℎminus(1198991205870) ]120591 and








uct(s)

(iv) p120591119879119881

and p119867119879



(v) p119898119879= minus(p120591

























119890and









minusrarr

120588minus]120591 and 120591


For 120591minus


















0

2

4

6

8

0 5

minus2

ln120582

CC e

ln 120582NCe

(a) ]120583NC+CC

0 5

0

2

4

6

8

minus2

ln120582

CC e

ln 120582NCe

(b) ]119890CC

0

2

4

6

8

0 5

minus2

minus4

ln120582

CC e

ln 120582NCe

(c) 120591 rarr 119890

0 5

0

2

4

6

8

minus2

minus4

ln120582

CC e

ln 120582NCe

IIIIII VI

VIV

(d) Data









120591

119881lt









1(1260)]120591 119886

minus

1rarr 1205880(770)120587

minus 1205880 rarr







119873(]120583 997888rarr ]120591) = 119873obs120583

sdot (

120590120591

120590120583

) sdot Br sdot (120576120591

120576120583

) (4)

where

(i) 119873obs120583









channel



119875 (]120583 997888rarr ]120591) lt 22 10minus4 (5)



1

1

10

E531

CCFR

NOMAD

CHORUS

CDHS

103

102

Δm2

(eV2

c4)

120583 rarr 120591

90 CL

sin2 2120579












CC Interactions



0025

005

0075

01

0125

015

0175

02

0225

025


I II

III

V

IV

06 08 1120572

pT

int

(GeV

)






region







0


+120587minus Λ rarr 119901120587




where 119901int119879


(119901+


119871)(119901+

119871+119901minus











119904 97 for Λ and 90 for Λ



(676 plusmn 006) for 119870119904



(6)







lowast

L 119882









119911 rarr 0




0 lt 1199012



Λ






1

119873

d119873119889Ω

= (

1

4120587

) (1 + 120572ΛP sdot k) (7)



















119873120583120583119888 = 119873120583120583+ minus 119873120583120583+119887119892

(8)





10

0

2

4

6

8


102

E (GeV)

times10minus3

E53A+ E53B

120590120583120583

120590CC




119877120583120583 =

120590120583120583

120590CCcong

119873120583120583119888

119873CC (9)





119898119888 = (1159 plusmn 0075) GeVc2 (10)


119861120583 (119864]) =(0097 plusmn 0003)

1 + (67 plusmn 18Gev) 119864] (11)


120581119904 = 0591 plusmn 0019 at 1198762 = 20GeV2c2 (12)



















0


0


+Σlowastminus


minus respectively





0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Com

bina

tions

10

MeV

M(120587+120587minus) (GeVc)05 06 07 08 09 1 11 12 13 14 15


dences for 1205880(770) 1198910(980) and 119891


ground suppression














2)=119865119860(0)(1+119876



















2

1205914






+119890minus











2

1205914in the

(1198984 1198802


140MeVc2

9 Conclusion






References






















120583 V119890rarr V120591



120583rarr V120591


120583rarr V120591





rarr V120591



119890rarr V120591



rarr V119890

























0(980) and f

2(1270) mesons in ]

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




(a) (b)

(c) (d)








chambersMuon

beamNeutrino

calorimeterHadronic

modulesTRD

Dipole magnet


calorimeterFront

Veto planes

x

y

z

1m

otimes

otimes B = 04T

V8

Preshower












120590119901

119901

sim

005

radic (119871)

+

0008pradic(1198715)

(2)



Entr

ies

0

500

1000

1500

2000

2500

3000

3500

4000

4500skins

Kevlar

Gas

gap

Hon

eyco

mb

Hon

eyco

mb

Hon

eyco

mb

Hon

eyco

mb

Gas

gap

Gas

gap
















45

40

35

30

25

20

15

10

5

00 5 10 15 20 25

(au

)

10GeV pions

10GeV electrons

Energy (keV)






























































0

001

002

003

004

005

006

007

042 044 046 048 05 052 054 056 058

(au

)

MK (GeVc2)

120590 = 109 (MeVc2)MC mean = 4972

120590 = 112 (MeVc2)Data mean = 4979




0

20

40

60

80

100

120

140

160

180 Entries

Const

Mpi0

Std

BkgConst

BkgMean

BkgRMS

3211

106181

1175 plusmn 8175



5197 plusmn 9839




1205942ndf












Oscillation





minus]119890]120591 ℎminus(1198991205870) ]120591 and








uct(s)

(iv) p120591119879119881

and p119867119879



(v) p119898119879= minus(p120591

























119890and









minusrarr

120588minus]120591 and 120591


For 120591minus


















0

2

4

6

8

0 5

minus2

ln120582

CC e

ln 120582NCe

(a) ]120583NC+CC

0 5

0

2

4

6

8

minus2

ln120582

CC e

ln 120582NCe

(b) ]119890CC

0

2

4

6

8

0 5

minus2

minus4

ln120582

CC e

ln 120582NCe

(c) 120591 rarr 119890

0 5

0

2

4

6

8

minus2

minus4

ln120582

CC e

ln 120582NCe

IIIIII VI

VIV

(d) Data









120591

119881lt









1(1260)]120591 119886

minus

1rarr 1205880(770)120587

minus 1205880 rarr







119873(]120583 997888rarr ]120591) = 119873obs120583

sdot (

120590120591

120590120583

) sdot Br sdot (120576120591

120576120583

) (4)

where

(i) 119873obs120583









channel



119875 (]120583 997888rarr ]120591) lt 22 10minus4 (5)



1

1

10

E531

CCFR

NOMAD

CHORUS

CDHS

103

102

Δm2

(eV2

c4)

120583 rarr 120591

90 CL

sin2 2120579












CC Interactions



0025

005

0075

01

0125

015

0175

02

0225

025


I II

III

V

IV

06 08 1120572

pT

int

(GeV

)






region







0


+120587minus Λ rarr 119901120587




where 119901int119879


(119901+


119871)(119901+

119871+119901minus











119904 97 for Λ and 90 for Λ



(676 plusmn 006) for 119870119904



(6)







lowast

L 119882









119911 rarr 0




0 lt 1199012



Λ






1

119873

d119873119889Ω

= (

1

4120587

) (1 + 120572ΛP sdot k) (7)



















119873120583120583119888 = 119873120583120583+ minus 119873120583120583+119887119892

(8)





10

0

2

4

6

8


102

E (GeV)

times10minus3

E53A+ E53B

120590120583120583

120590CC




119877120583120583 =

120590120583120583

120590CCcong

119873120583120583119888

119873CC (9)





119898119888 = (1159 plusmn 0075) GeVc2 (10)


119861120583 (119864]) =(0097 plusmn 0003)

1 + (67 plusmn 18Gev) 119864] (11)


120581119904 = 0591 plusmn 0019 at 1198762 = 20GeV2c2 (12)



















0


0


+Σlowastminus


minus respectively





0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Com

bina

tions

10

MeV

M(120587+120587minus) (GeVc)05 06 07 08 09 1 11 12 13 14 15


dences for 1205880(770) 1198910(980) and 119891


ground suppression














2)=119865119860(0)(1+119876



















2

1205914






+119890minus











2

1205914in the

(1198984 1198802


140MeVc2

9 Conclusion






References






















120583 V119890rarr V120591



120583rarr V120591


120583rarr V120591





rarr V120591



119890rarr V120591



rarr V119890

























0(980) and f

2(1270) mesons in ]

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




chambersMuon

beamNeutrino

calorimeterHadronic

modulesTRD

Dipole magnet


calorimeterFront

Veto planes

x

y

z

1m

otimes

otimes B = 04T

V8

Preshower












120590119901

119901

sim

005

radic (119871)

+

0008pradic(1198715)

(2)



Entr

ies

0

500

1000

1500

2000

2500

3000

3500

4000

4500skins

Kevlar

Gas

gap

Hon

eyco

mb

Hon

eyco

mb

Hon

eyco

mb

Hon

eyco

mb

Gas

gap

Gas

gap
















45

40

35

30

25

20

15

10

5

00 5 10 15 20 25

(au

)

10GeV pions

10GeV electrons

Energy (keV)






























































0

001

002

003

004

005

006

007

042 044 046 048 05 052 054 056 058

(au

)

MK (GeVc2)

120590 = 109 (MeVc2)MC mean = 4972

120590 = 112 (MeVc2)Data mean = 4979




0

20

40

60

80

100

120

140

160

180 Entries

Const

Mpi0

Std

BkgConst

BkgMean

BkgRMS

3211

106181

1175 plusmn 8175



5197 plusmn 9839




1205942ndf












Oscillation





minus]119890]120591 ℎminus(1198991205870) ]120591 and








uct(s)

(iv) p120591119879119881

and p119867119879



(v) p119898119879= minus(p120591

























119890and









minusrarr

120588minus]120591 and 120591


For 120591minus


















0

2

4

6

8

0 5

minus2

ln120582

CC e

ln 120582NCe

(a) ]120583NC+CC

0 5

0

2

4

6

8

minus2

ln120582

CC e

ln 120582NCe

(b) ]119890CC

0

2

4

6

8

0 5

minus2

minus4

ln120582

CC e

ln 120582NCe

(c) 120591 rarr 119890

0 5

0

2

4

6

8

minus2

minus4

ln120582

CC e

ln 120582NCe

IIIIII VI

VIV

(d) Data









120591

119881lt









1(1260)]120591 119886

minus

1rarr 1205880(770)120587

minus 1205880 rarr







119873(]120583 997888rarr ]120591) = 119873obs120583

sdot (

120590120591

120590120583

) sdot Br sdot (120576120591

120576120583

) (4)

where

(i) 119873obs120583









channel



119875 (]120583 997888rarr ]120591) lt 22 10minus4 (5)



1

1

10

E531

CCFR

NOMAD

CHORUS

CDHS

103

102

Δm2

(eV2

c4)

120583 rarr 120591

90 CL

sin2 2120579












CC Interactions



0025

005

0075

01

0125

015

0175

02

0225

025


I II

III

V

IV

06 08 1120572

pT

int

(GeV

)






region







0


+120587minus Λ rarr 119901120587




where 119901int119879


(119901+


119871)(119901+

119871+119901minus











119904 97 for Λ and 90 for Λ



(676 plusmn 006) for 119870119904



(6)







lowast

L 119882









119911 rarr 0




0 lt 1199012



Λ






1

119873

d119873119889Ω

= (

1

4120587

) (1 + 120572ΛP sdot k) (7)



















119873120583120583119888 = 119873120583120583+ minus 119873120583120583+119887119892

(8)





10

0

2

4

6

8


102

E (GeV)

times10minus3

E53A+ E53B

120590120583120583

120590CC




119877120583120583 =

120590120583120583

120590CCcong

119873120583120583119888

119873CC (9)





119898119888 = (1159 plusmn 0075) GeVc2 (10)


119861120583 (119864]) =(0097 plusmn 0003)

1 + (67 plusmn 18Gev) 119864] (11)


120581119904 = 0591 plusmn 0019 at 1198762 = 20GeV2c2 (12)



















0


0


+Σlowastminus


minus respectively





0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Com

bina

tions

10

MeV

M(120587+120587minus) (GeVc)05 06 07 08 09 1 11 12 13 14 15


dences for 1205880(770) 1198910(980) and 119891


ground suppression














2)=119865119860(0)(1+119876



















2

1205914






+119890minus











2

1205914in the

(1198984 1198802


140MeVc2

9 Conclusion






References






















120583 V119890rarr V120591



120583rarr V120591


120583rarr V120591





rarr V120591



119890rarr V120591



rarr V119890

























0(980) and f

2(1270) mesons in ]

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics





Entr

ies

0

500

1000

1500

2000

2500

3000

3500

4000

4500skins

Kevlar

Gas

gap

Hon

eyco

mb

Hon

eyco

mb

Hon

eyco

mb

Hon

eyco

mb

Gas

gap

Gas

gap
















45

40

35

30

25

20

15

10

5

00 5 10 15 20 25

(au

)

10GeV pions

10GeV electrons

Energy (keV)






























































0

001

002

003

004

005

006

007

042 044 046 048 05 052 054 056 058

(au

)

MK (GeVc2)

120590 = 109 (MeVc2)MC mean = 4972

120590 = 112 (MeVc2)Data mean = 4979




0

20

40

60

80

100

120

140

160

180 Entries

Const

Mpi0

Std

BkgConst

BkgMean

BkgRMS

3211

106181

1175 plusmn 8175



5197 plusmn 9839




1205942ndf












Oscillation





minus]119890]120591 ℎminus(1198991205870) ]120591 and








uct(s)

(iv) p120591119879119881

and p119867119879



(v) p119898119879= minus(p120591

























119890and









minusrarr

120588minus]120591 and 120591


For 120591minus


















0

2

4

6

8

0 5

minus2

ln120582

CC e

ln 120582NCe

(a) ]120583NC+CC

0 5

0

2

4

6

8

minus2

ln120582

CC e

ln 120582NCe

(b) ]119890CC

0

2

4

6

8

0 5

minus2

minus4

ln120582

CC e

ln 120582NCe

(c) 120591 rarr 119890

0 5

0

2

4

6

8

minus2

minus4

ln120582

CC e

ln 120582NCe

IIIIII VI

VIV

(d) Data









120591

119881lt









1(1260)]120591 119886

minus

1rarr 1205880(770)120587

minus 1205880 rarr







119873(]120583 997888rarr ]120591) = 119873obs120583

sdot (

120590120591

120590120583

) sdot Br sdot (120576120591

120576120583

) (4)

where

(i) 119873obs120583









channel



119875 (]120583 997888rarr ]120591) lt 22 10minus4 (5)



1

1

10

E531

CCFR

NOMAD

CHORUS

CDHS

103

102

Δm2

(eV2

c4)

120583 rarr 120591

90 CL

sin2 2120579












CC Interactions



0025

005

0075

01

0125

015

0175

02

0225

025


I II

III

V

IV

06 08 1120572

pT

int

(GeV

)






region







0


+120587minus Λ rarr 119901120587




where 119901int119879


(119901+


119871)(119901+

119871+119901minus











119904 97 for Λ and 90 for Λ



(676 plusmn 006) for 119870119904



(6)







lowast

L 119882









119911 rarr 0




0 lt 1199012



Λ






1

119873

d119873119889Ω

= (

1

4120587

) (1 + 120572ΛP sdot k) (7)



















119873120583120583119888 = 119873120583120583+ minus 119873120583120583+119887119892

(8)





10

0

2

4

6

8


102

E (GeV)

times10minus3

E53A+ E53B

120590120583120583

120590CC




119877120583120583 =

120590120583120583

120590CCcong

119873120583120583119888

119873CC (9)





119898119888 = (1159 plusmn 0075) GeVc2 (10)


119861120583 (119864]) =(0097 plusmn 0003)

1 + (67 plusmn 18Gev) 119864] (11)


120581119904 = 0591 plusmn 0019 at 1198762 = 20GeV2c2 (12)



















0


0


+Σlowastminus


minus respectively





0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Com

bina

tions

10

MeV

M(120587+120587minus) (GeVc)05 06 07 08 09 1 11 12 13 14 15


dences for 1205880(770) 1198910(980) and 119891


ground suppression














2)=119865119860(0)(1+119876



















2

1205914






+119890minus











2

1205914in the

(1198984 1198802


140MeVc2

9 Conclusion






References






















120583 V119890rarr V120591



120583rarr V120591


120583rarr V120591





rarr V120591



119890rarr V120591



rarr V119890

























0(980) and f

2(1270) mesons in ]

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




45

40

35

30

25

20

15

10

5

00 5 10 15 20 25

(au

)

10GeV pions

10GeV electrons

Energy (keV)






























































0

001

002

003

004

005

006

007

042 044 046 048 05 052 054 056 058

(au

)

MK (GeVc2)

120590 = 109 (MeVc2)MC mean = 4972

120590 = 112 (MeVc2)Data mean = 4979




0

20

40

60

80

100

120

140

160

180 Entries

Const

Mpi0

Std

BkgConst

BkgMean

BkgRMS

3211

106181

1175 plusmn 8175



5197 plusmn 9839




1205942ndf












Oscillation





minus]119890]120591 ℎminus(1198991205870) ]120591 and








uct(s)

(iv) p120591119879119881

and p119867119879



(v) p119898119879= minus(p120591

























119890and









minusrarr

120588minus]120591 and 120591


For 120591minus


















0

2

4

6

8

0 5

minus2

ln120582

CC e

ln 120582NCe

(a) ]120583NC+CC

0 5

0

2

4

6

8

minus2

ln120582

CC e

ln 120582NCe

(b) ]119890CC

0

2

4

6

8

0 5

minus2

minus4

ln120582

CC e

ln 120582NCe

(c) 120591 rarr 119890

0 5

0

2

4

6

8

minus2

minus4

ln120582

CC e

ln 120582NCe

IIIIII VI

VIV

(d) Data









120591

119881lt









1(1260)]120591 119886

minus

1rarr 1205880(770)120587

minus 1205880 rarr







119873(]120583 997888rarr ]120591) = 119873obs120583

sdot (

120590120591

120590120583

) sdot Br sdot (120576120591

120576120583

) (4)

where

(i) 119873obs120583









channel



119875 (]120583 997888rarr ]120591) lt 22 10minus4 (5)



1

1

10

E531

CCFR

NOMAD

CHORUS

CDHS

103

102

Δm2

(eV2

c4)

120583 rarr 120591

90 CL

sin2 2120579












CC Interactions



0025

005

0075

01

0125

015

0175

02

0225

025


I II

III

V

IV

06 08 1120572

pT

int

(GeV

)






region







0


+120587minus Λ rarr 119901120587




where 119901int119879


(119901+


119871)(119901+

119871+119901minus











119904 97 for Λ and 90 for Λ



(676 plusmn 006) for 119870119904



(6)







lowast

L 119882









119911 rarr 0




0 lt 1199012



Λ






1

119873

d119873119889Ω

= (

1

4120587

) (1 + 120572ΛP sdot k) (7)



















119873120583120583119888 = 119873120583120583+ minus 119873120583120583+119887119892

(8)





10

0

2

4

6

8


102

E (GeV)

times10minus3

E53A+ E53B

120590120583120583

120590CC




119877120583120583 =

120590120583120583

120590CCcong

119873120583120583119888

119873CC (9)





119898119888 = (1159 plusmn 0075) GeVc2 (10)


119861120583 (119864]) =(0097 plusmn 0003)

1 + (67 plusmn 18Gev) 119864] (11)


120581119904 = 0591 plusmn 0019 at 1198762 = 20GeV2c2 (12)



















0


0


+Σlowastminus


minus respectively





0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Com

bina

tions

10

MeV

M(120587+120587minus) (GeVc)05 06 07 08 09 1 11 12 13 14 15


dences for 1205880(770) 1198910(980) and 119891


ground suppression














2)=119865119860(0)(1+119876



















2

1205914






+119890minus











2

1205914in the

(1198984 1198802


140MeVc2

9 Conclusion






References






















120583 V119890rarr V120591



120583rarr V120591


120583rarr V120591





rarr V120591



119890rarr V120591



rarr V119890

























0(980) and f

2(1270) mesons in ]

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics

















































0

001

002

003

004

005

006

007

042 044 046 048 05 052 054 056 058

(au

)

MK (GeVc2)

120590 = 109 (MeVc2)MC mean = 4972

120590 = 112 (MeVc2)Data mean = 4979




0

20

40

60

80

100

120

140

160

180 Entries

Const

Mpi0

Std

BkgConst

BkgMean

BkgRMS

3211

106181

1175 plusmn 8175



5197 plusmn 9839




1205942ndf












Oscillation





minus]119890]120591 ℎminus(1198991205870) ]120591 and








uct(s)

(iv) p120591119879119881

and p119867119879



(v) p119898119879= minus(p120591

























119890and









minusrarr

120588minus]120591 and 120591


For 120591minus


















0

2

4

6

8

0 5

minus2

ln120582

CC e

ln 120582NCe

(a) ]120583NC+CC

0 5

0

2

4

6

8

minus2

ln120582

CC e

ln 120582NCe

(b) ]119890CC

0

2

4

6

8

0 5

minus2

minus4

ln120582

CC e

ln 120582NCe

(c) 120591 rarr 119890

0 5

0

2

4

6

8

minus2

minus4

ln120582

CC e

ln 120582NCe

IIIIII VI

VIV

(d) Data









120591

119881lt









1(1260)]120591 119886

minus

1rarr 1205880(770)120587

minus 1205880 rarr







119873(]120583 997888rarr ]120591) = 119873obs120583

sdot (

120590120591

120590120583

) sdot Br sdot (120576120591

120576120583

) (4)

where

(i) 119873obs120583









channel



119875 (]120583 997888rarr ]120591) lt 22 10minus4 (5)



1

1

10

E531

CCFR

NOMAD

CHORUS

CDHS

103

102

Δm2

(eV2

c4)

120583 rarr 120591

90 CL

sin2 2120579












CC Interactions



0025

005

0075

01

0125

015

0175

02

0225

025


I II

III

V

IV

06 08 1120572

pT

int

(GeV

)






region







0


+120587minus Λ rarr 119901120587




where 119901int119879


(119901+


119871)(119901+

119871+119901minus











119904 97 for Λ and 90 for Λ



(676 plusmn 006) for 119870119904



(6)







lowast

L 119882









119911 rarr 0




0 lt 1199012



Λ






1

119873

d119873119889Ω

= (

1

4120587

) (1 + 120572ΛP sdot k) (7)



















119873120583120583119888 = 119873120583120583+ minus 119873120583120583+119887119892

(8)





10

0

2

4

6

8


102

E (GeV)

times10minus3

E53A+ E53B

120590120583120583

120590CC




119877120583120583 =

120590120583120583

120590CCcong

119873120583120583119888

119873CC (9)





119898119888 = (1159 plusmn 0075) GeVc2 (10)


119861120583 (119864]) =(0097 plusmn 0003)

1 + (67 plusmn 18Gev) 119864] (11)


120581119904 = 0591 plusmn 0019 at 1198762 = 20GeV2c2 (12)



















0


0


+Σlowastminus


minus respectively





0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Com

bina

tions

10

MeV

M(120587+120587minus) (GeVc)05 06 07 08 09 1 11 12 13 14 15


dences for 1205880(770) 1198910(980) and 119891


ground suppression














2)=119865119860(0)(1+119876



















2

1205914






+119890minus











2

1205914in the

(1198984 1198802


140MeVc2

9 Conclusion






References






















120583 V119890rarr V120591



120583rarr V120591


120583rarr V120591





rarr V120591



119890rarr V120591



rarr V119890

























0(980) and f

2(1270) mesons in ]

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics











Oscillation





minus]119890]120591 ℎminus(1198991205870) ]120591 and








uct(s)

(iv) p120591119879119881

and p119867119879



(v) p119898119879= minus(p120591

























119890and









minusrarr

120588minus]120591 and 120591


For 120591minus


















0

2

4

6

8

0 5

minus2

ln120582

CC e

ln 120582NCe

(a) ]120583NC+CC

0 5

0

2

4

6

8

minus2

ln120582

CC e

ln 120582NCe

(b) ]119890CC

0

2

4

6

8

0 5

minus2

minus4

ln120582

CC e

ln 120582NCe

(c) 120591 rarr 119890

0 5

0

2

4

6

8

minus2

minus4

ln120582

CC e

ln 120582NCe

IIIIII VI

VIV

(d) Data









120591

119881lt









1(1260)]120591 119886

minus

1rarr 1205880(770)120587

minus 1205880 rarr







119873(]120583 997888rarr ]120591) = 119873obs120583

sdot (

120590120591

120590120583

) sdot Br sdot (120576120591

120576120583

) (4)

where

(i) 119873obs120583









channel



119875 (]120583 997888rarr ]120591) lt 22 10minus4 (5)



1

1

10

E531

CCFR

NOMAD

CHORUS

CDHS

103

102

Δm2

(eV2

c4)

120583 rarr 120591

90 CL

sin2 2120579












CC Interactions



0025

005

0075

01

0125

015

0175

02

0225

025


I II

III

V

IV

06 08 1120572

pT

int

(GeV

)






region







0


+120587minus Λ rarr 119901120587




where 119901int119879


(119901+


119871)(119901+

119871+119901minus











119904 97 for Λ and 90 for Λ



(676 plusmn 006) for 119870119904



(6)







lowast

L 119882









119911 rarr 0




0 lt 1199012



Λ






1

119873

d119873119889Ω

= (

1

4120587

) (1 + 120572ΛP sdot k) (7)



















119873120583120583119888 = 119873120583120583+ minus 119873120583120583+119887119892

(8)





10

0

2

4

6

8


102

E (GeV)

times10minus3

E53A+ E53B

120590120583120583

120590CC




119877120583120583 =

120590120583120583

120590CCcong

119873120583120583119888

119873CC (9)





119898119888 = (1159 plusmn 0075) GeVc2 (10)


119861120583 (119864]) =(0097 plusmn 0003)

1 + (67 plusmn 18Gev) 119864] (11)


120581119904 = 0591 plusmn 0019 at 1198762 = 20GeV2c2 (12)



















0


0


+Σlowastminus


minus respectively





0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Com

bina

tions

10

MeV

M(120587+120587minus) (GeVc)05 06 07 08 09 1 11 12 13 14 15


dences for 1205880(770) 1198910(980) and 119891


ground suppression














2)=119865119860(0)(1+119876



















2

1205914






+119890minus











2

1205914in the

(1198984 1198802


140MeVc2

9 Conclusion






References






















120583 V119890rarr V120591



120583rarr V120591


120583rarr V120591





rarr V120591



119890rarr V120591



rarr V119890

























0(980) and f

2(1270) mesons in ]

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics



















119890and









minusrarr

120588minus]120591 and 120591


For 120591minus


















0

2

4

6

8

0 5

minus2

ln120582

CC e

ln 120582NCe

(a) ]120583NC+CC

0 5

0

2

4

6

8

minus2

ln120582

CC e

ln 120582NCe

(b) ]119890CC

0

2

4

6

8

0 5

minus2

minus4

ln120582

CC e

ln 120582NCe

(c) 120591 rarr 119890

0 5

0

2

4

6

8

minus2

minus4

ln120582

CC e

ln 120582NCe

IIIIII VI

VIV

(d) Data









120591

119881lt









1(1260)]120591 119886

minus

1rarr 1205880(770)120587

minus 1205880 rarr







119873(]120583 997888rarr ]120591) = 119873obs120583

sdot (

120590120591

120590120583

) sdot Br sdot (120576120591

120576120583

) (4)

where

(i) 119873obs120583









channel



119875 (]120583 997888rarr ]120591) lt 22 10minus4 (5)



1

1

10

E531

CCFR

NOMAD

CHORUS

CDHS

103

102

Δm2

(eV2

c4)

120583 rarr 120591

90 CL

sin2 2120579












CC Interactions



0025

005

0075

01

0125

015

0175

02

0225

025


I II

III

V

IV

06 08 1120572

pT

int

(GeV

)






region







0


+120587minus Λ rarr 119901120587




where 119901int119879


(119901+


119871)(119901+

119871+119901minus











119904 97 for Λ and 90 for Λ



(676 plusmn 006) for 119870119904



(6)







lowast

L 119882









119911 rarr 0




0 lt 1199012



Λ






1

119873

d119873119889Ω

= (

1

4120587

) (1 + 120572ΛP sdot k) (7)



















119873120583120583119888 = 119873120583120583+ minus 119873120583120583+119887119892

(8)





10

0

2

4

6

8


102

E (GeV)

times10minus3

E53A+ E53B

120590120583120583

120590CC




119877120583120583 =

120590120583120583

120590CCcong

119873120583120583119888

119873CC (9)





119898119888 = (1159 plusmn 0075) GeVc2 (10)


119861120583 (119864]) =(0097 plusmn 0003)

1 + (67 plusmn 18Gev) 119864] (11)


120581119904 = 0591 plusmn 0019 at 1198762 = 20GeV2c2 (12)



















0


0


+Σlowastminus


minus respectively





0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Com

bina

tions

10

MeV

M(120587+120587minus) (GeVc)05 06 07 08 09 1 11 12 13 14 15


dences for 1205880(770) 1198910(980) and 119891


ground suppression














2)=119865119860(0)(1+119876



















2

1205914






+119890minus











2

1205914in the

(1198984 1198802


140MeVc2

9 Conclusion






References






















120583 V119890rarr V120591



120583rarr V120591


120583rarr V120591





rarr V120591



119890rarr V120591



rarr V119890

























0(980) and f

2(1270) mesons in ]

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




0

2

4

6

8

0 5

minus2

ln120582

CC e

ln 120582NCe

(a) ]120583NC+CC

0 5

0

2

4

6

8

minus2

ln120582

CC e

ln 120582NCe

(b) ]119890CC

0

2

4

6

8

0 5

minus2

minus4

ln120582

CC e

ln 120582NCe

(c) 120591 rarr 119890

0 5

0

2

4

6

8

minus2

minus4

ln120582

CC e

ln 120582NCe

IIIIII VI

VIV

(d) Data









120591

119881lt









1(1260)]120591 119886

minus

1rarr 1205880(770)120587

minus 1205880 rarr







119873(]120583 997888rarr ]120591) = 119873obs120583

sdot (

120590120591

120590120583

) sdot Br sdot (120576120591

120576120583

) (4)

where

(i) 119873obs120583









channel



119875 (]120583 997888rarr ]120591) lt 22 10minus4 (5)



1

1

10

E531

CCFR

NOMAD

CHORUS

CDHS

103

102

Δm2

(eV2

c4)

120583 rarr 120591

90 CL

sin2 2120579












CC Interactions



0025

005

0075

01

0125

015

0175

02

0225

025


I II

III

V

IV

06 08 1120572

pT

int

(GeV

)






region







0


+120587minus Λ rarr 119901120587




where 119901int119879


(119901+


119871)(119901+

119871+119901minus











119904 97 for Λ and 90 for Λ



(676 plusmn 006) for 119870119904



(6)







lowast

L 119882









119911 rarr 0




0 lt 1199012



Λ






1

119873

d119873119889Ω

= (

1

4120587

) (1 + 120572ΛP sdot k) (7)



















119873120583120583119888 = 119873120583120583+ minus 119873120583120583+119887119892

(8)





10

0

2

4

6

8


102

E (GeV)

times10minus3

E53A+ E53B

120590120583120583

120590CC




119877120583120583 =

120590120583120583

120590CCcong

119873120583120583119888

119873CC (9)





119898119888 = (1159 plusmn 0075) GeVc2 (10)


119861120583 (119864]) =(0097 plusmn 0003)

1 + (67 plusmn 18Gev) 119864] (11)


120581119904 = 0591 plusmn 0019 at 1198762 = 20GeV2c2 (12)



















0


0


+Σlowastminus


minus respectively





0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Com

bina

tions

10

MeV

M(120587+120587minus) (GeVc)05 06 07 08 09 1 11 12 13 14 15


dences for 1205880(770) 1198910(980) and 119891


ground suppression














2)=119865119860(0)(1+119876



















2

1205914






+119890minus











2

1205914in the

(1198984 1198802


140MeVc2

9 Conclusion






References






















120583 V119890rarr V120591



120583rarr V120591


120583rarr V120591





rarr V120591



119890rarr V120591



rarr V119890

























0(980) and f

2(1270) mesons in ]

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics







119873(]120583 997888rarr ]120591) = 119873obs120583

sdot (

120590120591

120590120583

) sdot Br sdot (120576120591

120576120583

) (4)

where

(i) 119873obs120583









channel



119875 (]120583 997888rarr ]120591) lt 22 10minus4 (5)



1

1

10

E531

CCFR

NOMAD

CHORUS

CDHS

103

102

Δm2

(eV2

c4)

120583 rarr 120591

90 CL

sin2 2120579












CC Interactions



0025

005

0075

01

0125

015

0175

02

0225

025


I II

III

V

IV

06 08 1120572

pT

int

(GeV

)






region







0


+120587minus Λ rarr 119901120587




where 119901int119879


(119901+


119871)(119901+

119871+119901minus











119904 97 for Λ and 90 for Λ



(676 plusmn 006) for 119870119904



(6)







lowast

L 119882









119911 rarr 0




0 lt 1199012



Λ






1

119873

d119873119889Ω

= (

1

4120587

) (1 + 120572ΛP sdot k) (7)



















119873120583120583119888 = 119873120583120583+ minus 119873120583120583+119887119892

(8)





10

0

2

4

6

8


102

E (GeV)

times10minus3

E53A+ E53B

120590120583120583

120590CC




119877120583120583 =

120590120583120583

120590CCcong

119873120583120583119888

119873CC (9)





119898119888 = (1159 plusmn 0075) GeVc2 (10)


119861120583 (119864]) =(0097 plusmn 0003)

1 + (67 plusmn 18Gev) 119864] (11)


120581119904 = 0591 plusmn 0019 at 1198762 = 20GeV2c2 (12)



















0


0


+Σlowastminus


minus respectively





0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Com

bina

tions

10

MeV

M(120587+120587minus) (GeVc)05 06 07 08 09 1 11 12 13 14 15


dences for 1205880(770) 1198910(980) and 119891


ground suppression














2)=119865119860(0)(1+119876



















2

1205914






+119890minus











2

1205914in the

(1198984 1198802


140MeVc2

9 Conclusion






References






















120583 V119890rarr V120591



120583rarr V120591


120583rarr V120591





rarr V120591



119890rarr V120591



rarr V119890

























0(980) and f

2(1270) mesons in ]

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




0025

005

0075

01

0125

015

0175

02

0225

025


I II

III

V

IV

06 08 1120572

pT

int

(GeV

)






region







0


+120587minus Λ rarr 119901120587




where 119901int119879


(119901+


119871)(119901+

119871+119901minus











119904 97 for Λ and 90 for Λ



(676 plusmn 006) for 119870119904



(6)







lowast

L 119882









119911 rarr 0




0 lt 1199012



Λ






1

119873

d119873119889Ω

= (

1

4120587

) (1 + 120572ΛP sdot k) (7)



















119873120583120583119888 = 119873120583120583+ minus 119873120583120583+119887119892

(8)





10

0

2

4

6

8


102

E (GeV)

times10minus3

E53A+ E53B

120590120583120583

120590CC




119877120583120583 =

120590120583120583

120590CCcong

119873120583120583119888

119873CC (9)





119898119888 = (1159 plusmn 0075) GeVc2 (10)


119861120583 (119864]) =(0097 plusmn 0003)

1 + (67 plusmn 18Gev) 119864] (11)


120581119904 = 0591 plusmn 0019 at 1198762 = 20GeV2c2 (12)



















0


0


+Σlowastminus


minus respectively





0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Com

bina

tions

10

MeV

M(120587+120587minus) (GeVc)05 06 07 08 09 1 11 12 13 14 15


dences for 1205880(770) 1198910(980) and 119891


ground suppression














2)=119865119860(0)(1+119876



















2

1205914






+119890minus











2

1205914in the

(1198984 1198802


140MeVc2

9 Conclusion






References






















120583 V119890rarr V120591



120583rarr V120591


120583rarr V120591





rarr V120591



119890rarr V120591



rarr V119890

























0(980) and f

2(1270) mesons in ]

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics






0 lt 1199012



Λ






1

119873

d119873119889Ω

= (

1

4120587

) (1 + 120572ΛP sdot k) (7)



















119873120583120583119888 = 119873120583120583+ minus 119873120583120583+119887119892

(8)





10

0

2

4

6

8


102

E (GeV)

times10minus3

E53A+ E53B

120590120583120583

120590CC




119877120583120583 =

120590120583120583

120590CCcong

119873120583120583119888

119873CC (9)





119898119888 = (1159 plusmn 0075) GeVc2 (10)


119861120583 (119864]) =(0097 plusmn 0003)

1 + (67 plusmn 18Gev) 119864] (11)


120581119904 = 0591 plusmn 0019 at 1198762 = 20GeV2c2 (12)



















0


0


+Σlowastminus


minus respectively





0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Com

bina

tions

10

MeV

M(120587+120587minus) (GeVc)05 06 07 08 09 1 11 12 13 14 15


dences for 1205880(770) 1198910(980) and 119891


ground suppression














2)=119865119860(0)(1+119876



















2

1205914






+119890minus











2

1205914in the

(1198984 1198802


140MeVc2

9 Conclusion






References






















120583 V119890rarr V120591



120583rarr V120591


120583rarr V120591





rarr V120591



119890rarr V120591



rarr V119890

























0(980) and f

2(1270) mesons in ]

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




10

0

2

4

6

8


102

E (GeV)

times10minus3

E53A+ E53B

120590120583120583

120590CC




119877120583120583 =

120590120583120583

120590CCcong

119873120583120583119888

119873CC (9)





119898119888 = (1159 plusmn 0075) GeVc2 (10)


119861120583 (119864]) =(0097 plusmn 0003)

1 + (67 plusmn 18Gev) 119864] (11)


120581119904 = 0591 plusmn 0019 at 1198762 = 20GeV2c2 (12)



















0


0


+Σlowastminus


minus respectively





0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Com

bina

tions

10

MeV

M(120587+120587minus) (GeVc)05 06 07 08 09 1 11 12 13 14 15


dences for 1205880(770) 1198910(980) and 119891


ground suppression














2)=119865119860(0)(1+119876



















2

1205914






+119890minus











2

1205914in the

(1198984 1198802


140MeVc2

9 Conclusion






References






















120583 V119890rarr V120591



120583rarr V120591


120583rarr V120591





rarr V120591



119890rarr V120591



rarr V119890

























0(980) and f

2(1270) mesons in ]

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Com

bina

tions

10

MeV

M(120587+120587minus) (GeVc)05 06 07 08 09 1 11 12 13 14 15


dences for 1205880(770) 1198910(980) and 119891


ground suppression














2)=119865119860(0)(1+119876



















2

1205914






+119890minus











2

1205914in the

(1198984 1198802


140MeVc2

9 Conclusion






References






















120583 V119890rarr V120591



120583rarr V120591


120583rarr V120591





rarr V120591



119890rarr V120591



rarr V119890

























0(980) and f

2(1270) mesons in ]

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics














2

1205914






+119890minus











2

1205914in the

(1198984 1198802


140MeVc2

9 Conclusion






References






















120583 V119890rarr V120591



120583rarr V120591


120583rarr V120591





rarr V120591



119890rarr V120591



rarr V119890

























0(980) and f

2(1270) mesons in ]

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics






References






















120583 V119890rarr V120591



120583rarr V120591


120583rarr V120591





rarr V120591



119890rarr V120591



rarr V119890

























0(980) and f

2(1270) mesons in ]

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics








0(980) and f

2(1270) mesons in ]

























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics








FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics



review article the nomad experiment at cern · 2019. 7. 31. · e nomad detector was located at the...

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