icarus-t600 collaboration carlo rubbia univ. of pavia, italy and infn, sezione pavia (oct. 3,2006)
DESCRIPTION
Icarus-T600 Collaboration Carlo Rubbia Univ. of Pavia, Italy and INFN, Sezione Pavia (Oct. 3,2006). Progress Report to the SPS-C. Which is the future of neutrino physics ?. - PowerPoint PPT PresentationTRANSCRIPT
1
Icarus-T600 Collaboration
Carlo Rubbia
Univ. of Pavia, Italyand INFN, Sezione Pavia
(Oct. 3,2006)
Progress Report to the SPS-C
SPS-C Oct 3, 2006 Slide# : 2
Which is the future of neutrino physics ? The experimental results of the recent years have profoundly changed the
pattern of neutrino physics.And, very likely, this is only a beginning.
Neutrinos have been shown to strongly oscillate between available
flavours while they propagate through space, whenever a sufficient
distance is provided from the source (solar, cosmic, accelerator or
reactor) and the detector.
All produced and observed neutrinos and antineutrino have left-handed or
right-handed helicities. These are the only chiralities included in the
Standard Model. But since they have mass, the presence of other
chiralities is not without problems.
Maybe their counterparts (right-handed neutrinos and left-handed
antineutrinos) simply do not exist and neutrino and antineutrino are in
fact the same particle. The key experiment for the search of Majorana
neutrinos is the neutrino-less double beta decay, actively investigated
at the Gran Sasso.
If their counterparts instead do exist, it may be that their properties
are substantially different from the ones of observable neutrinos and
antineutrinos.
SPS-C Oct 3, 2006 Slide# : 3
How many neutrinos are present in nature ? According to the LEP result, three different
neutrinos are coupled with Z-bosons.
Consequently there are only 2 independent m2.
But the possibility of one or more additional, “sterile” kinds of neutrino — namely of neutrinos which do not participate in the weak interactions — is unaffected by these Z-boson-based measurements.
The existence for such additional neutrino particles has been claimed by a Los Alamos experiment called LSND, in which they have been created through oscillations from ordinary neutrinos. ,
It is possible that neutrinos are something very different than just a neutral counterpart of charged leptons and may couple to another segment of the Universe, the one of sterile neutrinos, which do not see fully ordinary electro-weak interactions but still introduce mixing oscillations with ordinary neutrinos.
SPS-C Oct 3, 2006 Slide# : 4
LSND: Evidence for ( e)
Beam relatedbackgrounds
Excess of events: 87.9 22.4 6.0
Expectation for
oscillations
Data points afterbackground subtraction
The experimental evidence is very strong, namely 3.8 s.d.The experimental result so far has not been challenged experimentally
SPS-C Oct 3, 2006 Slide# : 5
Present experimental status with many possible explanations
allowed regions left 1. CPT violation, with LSND related to
anti-neutrino and no need of more neutrinos ??
2. CPT conservation and one or more sterile neutrinos, weakly coupled to ordinary neutrinos. They do interact weakly via W or Z, but standard might oscillate to them ?
3. Which connections to Cosmology ??
Needs experimental confirmations: MiniBoone at FermiLab ICARUS-T600 at CNGS
Explanations ??
SPS-C Oct 3, 2006 Slide# : 6
BooNE: Booster Neutrino ExperimentY. Liu, I. Stancu AlabamaS. Koutsoliotas BucknellE. Hawker, R.A. Johnson, J.L. Raaf CincinnatiT. Hart, E.D. Zimmerman ColoradoAguilar-Azevedo, L. Bugel, J.M. Conrad, J. Formaggio, J. Link, J. Monroe, D. Schmitz,M.H. Shaevitz, M. Sorel, G.P. Zeller ColumbiaD. Smith Embry RiddleL. Bartozek, C. Bhat, S.J. Brice, B.C. Brown,D.A. Finley, B.T. Fleming, R. Ford, F.G. Garcia,P. Kasper, T. Kobilarcik, I. Kourbanis,A. Malensek, W. Marsh, P. Martin, F. Mills,C. Moore, P.J. Nienaber, E. Prebys, A.D. Russell,P. Spentzouris, R. Stefanski, T. Williams FermilabD.C. Cox, A. Green, H.O. Meyer, R. Tayloe IndianaG.T. Garvey, C. Green, W.C. Louis, G. McGregor,S. McKenney, G.B. Mills, V. Sandberg, B. Sapp,R. Schirato, R. Van de Water, D.H. White Los AlamosR. Imlay, W. Metcalf, M. Sung, M.O. Wascko Louisiana StateJ. Cao, Y. Liu, B.P. Roe MichiganA.O. Bazarko, P.D. Meyers, R.B. Patterson,F.C. Shoemaker, H.A. Tanaka Princeton
protons mesons neutrinos
● 12 meters spherical steel tank
● 250,000 gallons of mineral oil (800 tons)
● 1280 PMT's in the main region (5.75 meters)
● 240 PMT in veto region
● Neutrino interactions in oil produce light (Cherenkov and scintillation)
● We measure time and charge for each tube
horn and target decay region absorber dirt (~450m) detector
SPS-C Oct 3, 2006 Slide# : 7
MiniBoone proposal:signal and backgrounds (Montecarlo)
Cross sections estimates for nuclear target, especially at low energies, have been widely underestimated in the original proposal
Cross sections estimates for nuclear target, especially at low energies, have been widely underestimated in the original proposal
SPS-C Oct 3, 2006 Slide# : 8
MiniBoone method for searching for oscillations
? ? ?
SPS-C Oct 3, 2006 Slide# : 9
CNGS physics potentials of ICARUS T600 The SPS schedule of CNGS foresees nominally 4.5 x1019 pot/y for the next five
years (2007-2012). This corresponds to a beam related rate ≈ 2500 ev/kton/year with 90 %
efficiency of collection. The T600 raw fiducial volume ≈ 480 t is equivalent nominally 1200 ev/y for
5 years, corresponding to ≈6000 beam related neutrino events. The T600 is also collecting simultaneously “self triggered” events. This in
particular represents:≈ 100 ev/year of individually recorded atmospheric CC cosmic rays.Solar neutrino electron rates >5 MeV.A zero background proton decay with 3 x 1032 nucleons for”exotic” channels.
T600 is a necessary intermediate technical step towards a much more massive LAr detector (3.3 kT LAr are equivalent to 20 kt NOVA scintillator), now being actively studied by INFN and US(Fermilab), but it offers also some interesting physics in itself. In the presentation I shall limit myself to two main topics:Searching for sterile neutrinos in T600 with deep e-like inelastic CC
events, complementary to MiniBooneThe proof of existence of decay with T600, the actual value of m2 being
already measured elsewhere by Soudan and S-K and in the future by OPERA.
SPS-C Oct 3, 2006 Slide# : 10
Search for sterile neutrinos at LNGS Both LSND and MiniBoone experiments are characterised by
<< 1 GeV quasi-elastic events in C with elaborate selection criteria
a relatively short oscillation path from the source to the detector The addition of substantial competing backgrounds due to
misinterpreted events.Therefore the signal should appear as an event excess peaking at low
values of the visible energy. In contrast, the CNGS beam and the ICARUS “bubble chamber”
identification is based on:Deep inelastic -e CC events recorded in the minimum bias mode.Extremely good background discrimination, limited only to the
intrinsic beam e contamination: ≤0.5% in the chosen E interval of 10 ÷ 30 GeV.
Excellent electron discrimination against converted ’s because of the differences in ionization losses in the earliest part of the track (No NC backgrounds).
Very long path-length which ensures several oscillations from source to detector in the foreseen LSND window, but still wide enough in order to identify maxima and minima related to m2, which can also be measured.
SPS-C Oct 3, 2006 Slide# : 11
Reconstructed CC events in T600
e-, 15 GeV, pT=1.16
GeV/c
Vertex: 10,2p,3n,2 ,1e-
CNGS e interaction, E=16.6 GeV120 cm
290 cm
CNGS interaction, E=21.3 GeV
Vertex: 3,5p,9n,3,1
80 c
m
300 cm
SPS-C Oct 3, 2006 Slide# : 12
Events with leading electron signature. The basic spectrum of LNGS is made of
with a most probable energy in the order of 25 GeV.
The spectrum has also been calculated and found to to be accurate to about 5%.
Electron shower events are extremely well identified experimentally, because of the ionization behaviour in the first cells after the vertex.
€
e−
€
o
electron (right) and pion (left) in T600
SPS-C Oct 3, 2006 Slide# : 13
Single wire
performance
10 MeV3.2 MeV1.8 MeV
Two consecutive
wires Noise
Threshold above noise ≈ 200 keV
SPS-C Oct 3, 2006 Slide# : 14
E:10 ÷ 30 GeVN():4635N(e,beam): 18.8N(e,oscill): 45.5
E:10 ÷ 30 GeVN():4635N(e,beam): 18.8N(e,oscill): 94.9
Indicative energy spectra for LSND signals
Hypothetical sterile neutrino oscillations (LSDN) m2 = 0.4 eV2
Hypothetical sterile neutrino oscillations (LSDN) m2 = 0.4 eV2
Hypothetical sterile neutrino oscillations (LSDN) m2 = 0.2 eV2
Hypothetical sterile neutrino oscillations (LSDN) m2 = 0.2 eV2
E resolution for contained events ≤ 0.17sqrt(E)
SPS-C Oct 3, 2006 Slide# : 15
Limits at T600 with 6000 events. Sensitivity region, in
terms of Standard Deviations , for 6000 raw CNGS neutrino events. The potential signal is above the background generated by the intrinsic e beam contamination, in the deep inelastic interval 10-30 GeV.
The m2 distribution extends widely beyond the LNSD and MiniBoone regions.
Two indicated points are reference values of MiniBoone proposal and of previous slide T600 at the CNGS offers an
unique possibility of searching for sterile neutrinos, largely complementary and comparable to
the Fermilab programme.
T600 at the CNGS offers an unique possibility of searching for sterile neutrinos, largely complementary and comparable to
the Fermilab programme.
SPS-C Oct 3, 2006 Slide# : 16
Searching for the signature.
e-, 9.5 GeV, pT=0.47 GeV/c
- e- + e + _
CNGS interaction, E=18.7 GeV280 cm
105 cm
The original international proposal for T1800, recently cancelled by lack of funding, would have ensured a number of events adequate to cover the signature with a sensitivity comparable to the one OPERA. The electron decay channel is however quite significant goal also for the presently reduced T600 mass, uniquely characterized by a large transverse momentum unbalance due to the emission of the two neutrinos.
SPS-C Oct 3, 2006 Slide# : 17
How many are necessary for a “signature” At the effective neutrino energy of 20 GeV and m2 = 2.5E-3
eV2, the expected => is 1.4%. Therefore for 6000 CNGS events in the T600 we expect 84 raw events.
The branching ratio for => eis 16%; hence we expect 13.4 electron deep inelastic events, in addition to the ≈ 14 intrinsic beam associated e with energy <20 GeV. This is already “per-se” a significant effect, namely with 27.4 electron events observed vs. 14 ± 3.7 expected (3.6 s.d.).
Events are absolutely clean and they are characterised by a momentum unbalance because of neutrino emission and a relatively low electron momentum. Selection criteria suggest a sufficiently clean separation from intrinsic beam associated e with kinematic cuts and an efficiency of 50%.
Therefore one should expect about 7 ± 2.6 => e events, some of which, hopefully, gold plated.
This should be sufficient for a proof of existence, the actual value of m2 being already measured elsewhere in Soudan and S-K.
SPS-C Oct 3, 2006 Slide# : 18
+ LSND like sterile neutrinos
-> e decays
Likelihood weight
e balanced events or tau decays ?
Likelihood distributions may separate an
hypothetical LSND excess from the expected presence of
decays
Likelihood distributions may separate an
hypothetical LSND excess from the expected presence of
decays
SPS-C Oct 3, 2006 Slide# : 19
General T600 layout
Dewar LN2 (30 m3)
Dewar LAr (30 m3)
Passive heaters
SPS-C Oct 3, 2006 Slide# : 20
SITE T600
Modules T600 parking site
Control RoomsICARUS & OPERA
OPERA building BAM
OPERA Service Area
Hall B logistics
SPS-C Oct 3, 2006 Slide# : 21
Leaving from SeregnoLeaving from Seregno
September 18th.The base insulation at SeregnoThe base insulation at Seregno
Transport to LNGS
SPS-C Oct 3, 2006 Slide# : 22
Sept. 20Sept. 20thth @ HALL B!Incoming…
Flying over OPERAFlying over OPERA.
IncomingIncoming
… … in the Hall in the Hall to the working area.to the working area.
SPS-C Oct 3, 2006 Slide# : 23
Sept. 22Sept. 22thth,, @ Seregno
The lateral panels on the road.The lateral panels on the road.
SPS-C Oct 3, 2006 Slide# : 24
New anti seismic and safety structures underground
• The steel structure has an anti seismic function. It also contributes to hold a maximum over-pressure of 100 mbar.
• The insulation will be a closed box, in order to contain hypothetical cryogenic leaks.
SPS-C Oct 3, 2006 Slide# : 25
JAN FEB MAR MAY JUN JUL2006
Top insulation assembled
Instrumentation
Cryo roof pass-through
2nd cryostat in place
Projected T600 planning of cryogenics
SPS-C Oct 3, 2006 Slide# : 26
ICARUS Cool-down Filling the T600 requires 2 x 275’000 litres (786.5 tons) of L Ar to
be transported by trucks from the outside into Hall B. The initial start-up procedure will be as follows:
1.Vacuum phase and cryostat fill with GasAr: 1 LAr truck to be kept in Hall B
2.N2 “pre-cooling”: 7 days duration 1 LN2 truck/2-3 days
3.N2 cooling: 7 days duration 1-2 LN2 trucks/ day
4.LAr filling: 10-20 days duration 1-2 LN2 trucks/ day
2-4 LAr trucks/ day
The normal running procedure will be as follows: Permanent general LNGS N2 facility: Stierling liquefiers inside the
laboratory, presumably ready only by the end of the 2007 Intermediate start up phase with additional N2 trucks from outside
(to be authorized) for the duration period before STIERLING/tank delivery
1 LN2 trucks/ 1-3 days
SPS-C Oct 3, 2006 Slide# : 27
SPS 2007 Accelerator Schedule (draft)
SPS-C Oct 3, 2006 Slide# : 28
Conclusion
In all likelihood, the T600 detector may be able to run for a major fraction of the
2007 schedule !