the opera long baseline neutrino experiment: status and first results luigi salvatore esposito...
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The OPERA long baseline neutrino experiment: status
and first results
Luigi Salvatore Esposito
Laboratori Nazionali del Gran Sasso
on behalf of the OPERA collaboration
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 2
Summary
• Aim and strategy of the experiment• OPERA detector• CNGS 2007 run• Neutrino interactions in a lead-emulsion
target• CNGS 2008 run• Conclusions
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 3
The OPERA collaboration
36 INSTITUTIONS, ~200 PHYSICISTS
Annecy, Lyon, Strasbourg
Dubna, Moscow(INR,LPI,ITEP,SINP
MSU) Obninsk
Zagreb
L’Aquila, Bari, Bologna, Frascati,
LNGS, Napoli, Padova, Roma, Salerno
BernNeuchatel
Zurich
Brussels
Hamburg, Münster,Rostock
Sofia
Aichi, TohoKobe, NagoyaUtsunomiya
Technion Haifa
METU Ankara
Gyeongsang
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 4
OPERA is designed for the direct observation of appearance in a pure νμ beam in order to provide a final confirmation of neutrino oscillations in the atmospheric sector
Physics motivations
best fit:
M.C. Gonzalez-Garcia et M.Maltoni arXiv:0704.1800 [hep-ph]
E(GeV)
L(Km)m27.1sin)(cos)2(sin)νν(P
2312
134
232
τμ
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 5
The Cern Neutrino to Gran Sasso (CNGS) program
CERN beam optimized to study the appearance by detection
Beam mean features:
L=730 km ; <E>=17 GeV
/ = 2.1% (e+ e)/ = 0.68% prompt negligible
730 Km
CERN
LNGS
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 6
Detection of the appearance signal
The challenge is to identify interactions from interactions
-
Decay “kink”
-
~1 mm
oscillation
-
h-n(
e- e
+--n(
B. R. ~ 17%
B. R. ~ 50%
B. R. ~ 18%
B. R. ~ 14%
decay modes
OPERA solution is a OPERA solution is a hybrid hybrid technique:technique:tracking apparatus with “many” tracking apparatus with “many” Emulsion Cloud Chamber target Emulsion Cloud Chamber target units (units (lead/emulsion structure)lead/emulsion structure)
• Long-baseline, flavour oscillation: small fraction of Long-baseline, flavour oscillation: small fraction of νν ::
Far-away source, low flux, weak interaction: Far-away source, low flux, weak interaction: →→ large large targettarget massmass required (as usual for required (as usual for ’s …)’s …)
• CC interactions of CC interactions of νν tagged by the tagged by the decaydecay (c(c = 87 = 87 μμmm)) : :
→→ need need high spatial resolutionhigh spatial resolution & & lepton Id lepton Id
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 7
Pb
Emulsion layers
1 mm
The brick is the target basic component:• 57 nuclear emulsion films interleaved by 1 mm thick lead plates • “Changeable Sheets doublet” made of two double refreshed emulsion films,vacuum packed and glued onto the bottom of each brick to connect TT- brick
2 emulsion layers (44 m thick)poured on a
205 m plastic base
130 000 m²
12.5cm
10.2cm
8.3 Kg
10 X0
Electron trackEmulsion:Measuring a vector in space(δx=1 μm δθ=1 mrad)
The OPERA target is composed of 155000 bricks
Emulsion analysis:
Vertex, decay kink, e/ ID, multiple scattering, kinematics measurements
on event-by-event basis! … limited by statistics
The OPERA target
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 8
Target Tracker + Brick Walls
Spectrometer
0 max
p.h.
OPERA: a hybrid detector
What the brick cannot do: trigger for a neutrino interaction muon identification and momentum/charge measurement need a hybrid detector
On-line analysis of electronic data
Brick finding algorithm
Selected brick is removed from the target and exposed to cosmic rays (alignment). Emulsions are developed and sent to scanning stations / labs
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 9
The OPERA detector
SM1 SM2
VetoBMS
Target tracker Spectrometer:XPC, HPT, RPC, magnet
Modular,Modular, Hybrid Hybrid Detector:Detector:Two Two supermodulessupermodules, each containing, each containing a a Target Target SectionSection - 31 Target - 31 Target WallsWalls to host target units ( to host target units (ECC bricksECC bricks)) - 31 Target - 31 Target Tracker modulesTracker modules (scintillator strips) (scintillator strips) a a Magnetic SpectrometerMagnetic Spectrometer (XPC, RPC, Drift tubes) (XPC, RPC, Drift tubes)• Upstream:Upstream: VETO (glass RPC) VETO (glass RPC)• Both sides:Both sides: BBrick rick MManipulation anipulation SSystem (BMS)ystem (BMS)• Nearby: Nearby: BBrick rick AAssembly ssembly MMachine (BAM) - achine (BAM) - Hall BHall B • Data Taking: (1) Data Taking: (1) DAQ DAQ nodes + time stamp [Gran Sasso]nodes + time stamp [Gran Sasso] (2) (2) Emulsion scanning Emulsion scanning [Europe and Japan][Europe and Japan]
… … && several facilities for brick & emulsion film handling several facilities for brick & emulsion film handling (X-ray systems, “Changeable sheets” refreshing and assembly, (X-ray systems, “Changeable sheets” refreshing and assembly, cosmic-ray exposure, film development)cosmic-ray exposure, film development)
CNGS beamCNGS beam
1919 mm
10 m10 m8 m8 m
Hall C Hall C -- Gran Sasso Gran Sasso Underground Lab (Italy)Underground Lab (Italy)
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 10
Status of brick production
Brick Assembly Machine: piling/pressing section
Brick Assembly Machine:wrapping section
• 9*106 emulsions & lead plates• 155 000 bricks to be produced• production rate ~ 700/day
Filling under completion, ~ 88% now
brick production/filling
020000400006000080000
100000120000140000160000180000
1 8 15 22 29 36 43 50 57 64 71 78 85 92
weeks
bri
ck
s
2 drums/day
2.5 drums/day
3 drums/day
real
June 10th July 28th
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 11
High speed CCD Camera (3 kHz)
Piezo-controlled objective lens
Constant speed stage
Synchronization of objective lens and stage
Off-line Data Taking~ 30 bricks will be daily extracted from target and analyzed using high-
speed automatic systemsSeveral labs distributed in Europe and Japan
S-UTS (Japan)
Customized commercial optics and mechanics + asynchronous DAQ software
Hard-coded algorithms
scanning speed ~ 20 cm2 / h
European Scanning System
Automated emulsion scanning
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 12
Automated emulsion analysis
• Predictions from electronic detectors are searched in the Changeable Sheet doublet.
• If an interaction is detected in the CS, the brick is exposed to cosmic rays (alignment) and the emulsions are developed and sent to scanning stations/labs
• The tracks measured in CSd are followed back inside the brick until tracks stop.
• A full scanning around neutrino interaction vertex is performed
• Finally the event topology and kinematics reconstructed is performed
Emulsion scanning is performed in a fully automatic way. About 40 microscopes are operational in the various OPERA scanning laboratories (Europe and Japan).
CC interaction
h
muon
2 cm
2 m
m
ECC brick
CS doublet
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 13
Track segments found in 8 consecutive plates
Passing-through tracks rejection
Vertex reconstruction
Momentum measurement by Multiple ScatteringdE/dx for /µ separation at low energy
Electron identification and energy measurement
3D reconstruction of particle tracks
16 tomographic images
2D Imageprocessing
40m emulsion sheet
Emulsion scanning
200 m
Field of viewField of view
0.2 m
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 14
Status of the experiment
May 2003: start of detector construction
May 2006: completion of electronic detectors commissioning
Aug 2006: technical run, 0.76*1018 pot collected
319 interactions in the rock, mechanical structure and iron of the spectrometer
Oct 2006: start of brick production
Oct 2007: short physics run (~40% target) 0.824*1018 pot collected
38 events collected in the target
May 2008: 135000 bricks inserted (~88% target)
Jun 2008: OPERA target will be completed. Start of full data taking, expected about 2.1*1019 pot in 130 days of SPS running.
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 15
2007 run: Interactions outside the Target
331 events passed the analysis cut303 had been expected:ratio similar to the one observed in 2006
Muon vertical angle Energy of the muon (RPC)
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 16
31.5 ± 6 expected events in bricks
38 events registered in the target (bricks + scintillators + walls extra 10% contribution) during the 2007 CNGS run:
• 29 CC-like• 9 NC-like
Brick handling, Film Processing, Scanning : first test on real neutrino interactions
2007 run: Interactions inside the Target
Event analysis is almost completed on this small sample
Unfortunately statistics has been quite limited.
Wall Finding: > 95%Brick Finding: 80% 7%Position accuracy: 2-3 cm
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 17
= 22 µm = 5 mrad
CS to brick connection: design accuracy
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 18
= 54 µm = 9 mrad
Systematical uncertainties (gap, marks, …) dominate
CS to brick connection: neutrino interactions
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 19
Scan-back accuracy
= 4 µm = 2 mrad
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 20
Example of CC interaction
5 prongs associated to the neutrino interaction
<IP> = 9 m
Electromagnetic shower pointing to the vertex ( conversion)
19 m
8 m
43 mm
17 m
m
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 21
Charm candidate Trk TX TY IP Momentum(GeV) Comment
1 0.005 0.036 3.30 1.7+0.5-0.3
2 0.005 0.139 1.01 - parent
3 0.002 0.064 6.64 >20.0 SB
4 -0.021 0.064 7.15 2.1+0.7-0.4 SB
5 -0.029 0.046 2.83 >8.4 SB
6 -0.031 0.064 7.32 2.4+0.8-0.5 SB
7 -0.076 0.068 4.19 1.8+1.6-0.6 SB
8 -0.089 0.141 6.88 2.5+1.4-0.7
9 -0.183 0.106 5.39 0.7+0.2-0.1
10 -0.297 -0.143 19.17 0.7+0.3-0.1
11 -0.067 0.008 7.26 3.5+3.6-1.2 e-pair
12 -0.069 0.005 16.80 2.0+3.1-0.8 e-pair
Secondary VertexDaughter momentum = 3.9 +1.7
-0.9
kink = 0.204 radFlight length = 3247 μmPt = 796 MeV
PtMIN = 606 MeV (90% C.L.)
Kink
PRELIMINARY
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 22
OPERA τ search sensitivity
- decay
channels
Signal ÷ m2 (Full mixing)
Background
2.5 x 10-3 (eV2) 3.0 x 10-3 (eV2)
- µ- 2.9 4.2 0.17
- e- 3.5 5.0 0.17
- h- 3.1 4.4 0.24
- 3h 0.9 1.3 0.17
ALL 10.4 15.0 0.76
• 5 years CNGS data taking ( 4.5 1019 pot/year )• 1.35 ktons target mass
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 23
OPERA observation probability
SK 90% CL(L/E analysis)
Dis
covery
pro
bab
ilit
y
%
Last MINOS measurement
3 σ sensitivity
4 σ sensitivity
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 24
The 2008 OPERA run
130 days for the CNGS (200)2.1*1019 p.o.t (4.5*1019)
Start: ~ June 20th
End: Nov 10th
Total number of interactions
2000
CC events 1500
NC events 450
ee events 13
Charm decay 85
Tau candidate (@2.5 10-3 eV2)
~ 1
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 25
The OPERA experiment is running- Electronic detectors fully commissioned- Target filling in progress (completed by June) Scanning labs are ready (~40 microscopes available)
The OPERA 2007 run allowed to test the full operation chain:- Test electronic detectors and data acquisition- Test the brick finding algorithm- Test brick handling- Test CS doublet scanning- Test the target tracker to brick matching and scanning strategy
The concept of the OPERA detector has been experimentally validated by measuring neutrino
events in the detector.
Conclusions
In June the first high luminosity OPERA run will start. With some luck we will measure the first candidate event by the end of this year!
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 26
BACKUP SLIDES
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 27
Time Selection of Beam Events
GPS
TCERN = Time Stamp SPS extraction
TOPERA = Event TimeStamp
Tflight = 2.44 msec
TOPERA - (TCERN + Tflight) < ∆TGate
GPS Time Stamp resolution ~ 100 ns
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 28
The 2006 commissioning run: CNGS and cosmics
50 ms
10.5 s 10.5 s
August 2006Integrated: 7.6x1017 p.o.t.319 “beam-related” events [New J. Phys. 8 (2006) 303]
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 29
τsearch: backgrounds
-
,e,e-
+
e+
h+
D+
Same decay topology as
Charm production in CC,common to the 3 channels
Good muon identification is fundamental
Primary lepton not identified
Coulombian large angle scattering of muons in Lead : Bck. to
Hadronic interactions in Pb: Bck. to hor to if hadron mis-identified as muon)
Expected number of background events after 5 years running with nominal beam:
h h
τe τμ τh τ3h TotalCharm background .173 .008 .134 .181 .496
Large angle μ scattering .096 .096
Hadronic background .077 .095 . .172
Total per channel .173 .181 .229 .181 .764
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 30
e oscillation search
13 SIGNAL e beam e NC CC
9° 9.3 18 4.5 5.2 1.0
7° 5.8 18 4.5 5.2 1.0
5° 3.0 18 4.6 5.2 1.0
mm232322 = 2.5 x 10-3 eV2 23 23 = 45° = 45°
nominal CNGS beam
Combined fit of ECombined fit of Eee, E, Evisvis, (pt), (pt)missmiss
to improve S/B ratioto improve S/B ratio
90% C.L. limits on sin90% C.L. limits on sin22(2(21313) and ) and 13 13 ::
sinsin22(2(21313)<0.05 )<0.05 13 13 < 7.1º< 7.1º
5 years
(pt)miss
GeV
2.5x10-3 eV2
7.1o6.4o
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 31
CNGS control electronics failure
The failed ventilation electronics were installed along the TSG4 (service gallery), next to the ventilation ducts, and in the TCV4 (ventilation chamber).
In both areas the radiation levels, as predicted by the FLUKA simulations and confirmed by the radiation protection measurements, are far too high for COTS components the electronics should have failed and they did!!
Designated “radiation safe”
areas for electronics
electronic equipment
electronic equipment
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 32
Actions for 2008 shutdown
General guideline:• Replace damaged electronics Replace damaged electronics • Move the electronics out of the CNGS tunnels as possibleMove the electronics out of the CNGS tunnels as possible
For the equipment which must stay in the area:For the equipment which must stay in the area:• Create a “radiation-safe” area by adding adequate shielding and move all the electronics Create a “radiation-safe” area by adding adequate shielding and move all the electronics into this areainto this area• Address the sensitivity to radiation of the installed electronics and investigate upgrade Address the sensitivity to radiation of the installed electronics and investigate upgrade possibilitiespossibilities• Install a radiation monitoring system for electronics as in LHCInstall a radiation monitoring system for electronics as in LHC
During the 2007/2008 shutdown, work is organized to remedy the problem and assure nominal running of the facility for 2008 and beyond.
Radiation damages repair and protection:• the work is fully funded• electronics repair and reshuffling has started, shielding plugs defined, civil engineering starting• completion of the work expected by the end of week 23 (June 6th)• stable beam during week 25 (~June 20th)
23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 33
Summary Event Location & Data analysis
Europe Japan
All event 19 (15 CC, 4 NC)
19 (14 CC, 5 NC)
Events confirmed in the CSd
18 18
Events located in the bricks
14 10
Interactions in dead material
1 1
CS-Brick mismatch 1 1
Analysis in progress 2 6
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