OPERA physics programme, experimental concept, first results with beam and cosmic, short term prospects.

Size: px

Start display at page:

Download "OPERA physics programme, experimental concept, first results with beam and cosmic, short term prospects."

Rebecca Cooper
5 years ago
Views:

1 OPERA physics programme, experimental concept, first results with beam and cosmic, short term prospects. EPS 2007 Manchester Gaston Wilquet IIHE Université Libre de Bruxelles for the OPERA Collaboration 21/7/2007 G.Wilquet - EPS

The OPERA Collaboration: 150 physicists, 36 institutions in 13 countries Belgium IIHE Brussels Bulgaria Sofia Croatia IRB Zagreb France LAPP Annecy IPNL Lyon IReS Strasbourg Germany Hamburg Münster

2 The OPERA Collaboration: 150 physicists, 36 institutions in 13 countries Belgium IIHE Brussels Bulgaria Sofia Croatia IRB Zagreb France LAPP Annecy IPNL Lyon IReS Strasbourg Germany Hamburg Münster Rostock Israel Technion Haifa Italy Bari Bologna LNF Frascati L Aquila, LNGS Naples Padova Rome Salerno Japan Aichi Toho Kobe Nagoya Utsunomiya Korea-South Jinju Russia INR Moscow NPI Moscow ITEP Moscow SINP MSU Moscow JINR Dubna Obninsk Switzerland Bern Neuchâtel ETH Zurich Tunisia Tunis Turkey METU Ankara 21/7/2007 G.Wilquet - EPS

Physics Programme: compelling evidences of neutrinos oscillation at all available sources: Sun, atmosphere, LBL reactors & accelerators Parameter space allowed for solar neutrinos and by KamLAND

3 Physics Programme: compelling evidences of neutrinos oscillation at all available sources: Sun, atmosphere, LBL reactors & accelerators Parameter space allowed for solar neutrinos and by KamLAND Parameter space allowed by Super-K and excluded by CHOOZ and Palo Verde Parameter space for atmospheric neutrinos allowed by Super-K L/E dependence of the measured to expected fluxes ratio of atmospheric ν μ by Super-K Parameter space allowed by K2K and MINOS No evidence yet of flavour APPEARANCE tagged by identification of l - emitted in CC interaction 21/7/2007 G.Wilquet - EPS

4 OPERA Main Physics Programme: tag the ν τ appearance in a ν μ beam by τ - identification Admitted dominant interpretation of ν μ disappearance in the atmospheric sector (neglecting matter effects): [ ] [ ] Δm ev L km P ν ν cosθ sin θ sin. μ τ EGeV cos θ sin 2θ 1. Δ m =. ev Compatible with full ν ν mixing and no ν admixture in ν μ τ e 3 21/7/2007 G.Wilquet - EPS

5 Design an experiment CNGS and OPERA - able to tag the ν τ appearance in a ν μ beam by τ - identification <E ν > well above ν τ CC threshold (3.6 GeV) for decent cross-section <E ν > / L not much different than Δm 2 for decent P osc Massive target to collect enough events High spatial resolution to resolve the τ - path length 1 mm Very low background not to dilute the expected low signal ( N ) σν τ σ ν N μ ν μ μ - E ν ( GeV ) τ - ν τ μ - ~1 mm 21/7/2007 G.Wilquet - EPS

OPERA Hybrid concept : Target cells Target is an assemblage of elementary autonomous cells or bricks based on Emulsion Cloud Chamber technique used by DONUT to observe directly the ν τ provides large

6 OPERA Hybrid concept : Target cells Target is an assemblage of elementary autonomous cells or bricks based on Emulsion Cloud Chamber technique used by DONUT to observe directly the ν τ provides large mass and micron and mrad precisions quasi on-line analysis : bricks in which events have occurred are removed and analysed on daily base - typically 25. Plastic base Emulsion layers ( 205 μm) 44 μm ( ) 1mm Pb τ μ ν τ Brick 56 lead plates interleaved with 57 sheets of nuclear emulsion cm, 8.3 kg. 10 X 0 ν τ N τ X μ νν τ μ Tracks : series of aligned segments in emulsion layers 21/7/2007 G.Wilquet - EPS

7 OPERA target : How to scan for tracks in an ECC Depth of field 3μm Emulsion layer thickness 44 μm 2D image : 15 tomographic views Track stubs 44 μm layer Lens field of view 200 μm Track segment: aligned track stubs 3D-track segments found in 8 consecutive plates Passing-through and low momentum tracks rejection Vertex reconstruction 21/7/2007 G.Wilquet - EPS

8 OPERA target : What you can see and reconstruct in an ECC View orthogonal to beam ν e vertex π 0 Primary electron Electron shower PEANUT rehearsal : bricks exposed to NuMI in front of MINOS near detector 21/7/2007 G.Wilquet - EPS

9 Particle ID and kinematics in ECC : de/dx (grain counting) and Coulomb multiple scattering ± 0 Particle ID e / π separation : electron tracks counting at vertex ( μ π ) separation (CMS) ± e / ±, ± de dx : efficiency > 90%, purity > 99% above 2 GeV / c ± μ / ± π separation in brick where track stops ( de dx and CMS) e.g. 65% μ efficiency, 3 % π misidentification Kinematics ± e energy from shower parametrization : ΔE E 025. ± ± μ,h momentum (CMS) e.g <Δ p p < 030. below 8 GeV / c Brick exposed to 8 GeV e - Pion misidentification (%) NN using de/dx CMS Muon identification (%) 21/7/2007 G.Wilquet - EPS

OPERA detector : Veto plane + 2 identical super-modules SM1 SM2 0.68 kton 0.68 kton μ ID, charge, p Δp/p < 25% Wrong charge < 0.3% μ ID, charge, p Veto plane (RPC) Target and Target Tracker (6.

10 OPERA detector : Veto plane + 2 identical super-modules SM1 SM kton 0.68 kton μ ID, charge, p Δp/p < 25% Wrong charge < 0.3% μ ID, charge, p Veto plane (RPC) Target and Target Tracker (6.7m) 2 Target : bricks, 29 walls High precision tracker Instrumented dipole magnet 6 4-fold layers of 1.53 T drift tubes 22 XY planes of RPC in Target tracker : 31 XY doublets of 256 both arms scintillator strips + WLS fibres + multianodes PMT for Muon spectrometer (8 10 m 2 ) Brick selection Calorimetry 21/7/2007 G.Wilquet - EPS

CERN Neutrino beam to Gran Sasso L=730km CERN

L km 10 730 2 2 3 2 Beam contamination νμ ν e +ν

11 CERN Neutrino beam to Gran Sasso L=730km CERN Energy spectrum maximizes P osc ( ) ν ν σ ε CC μ τ ντ τ at sin 2θ 23 = 1 ; Δm ev given L= 730km E 17GeV Δm ev 23 L km Beam contamination νμ ν e +ν ν μ e prompt ν τ 41.% 09.% 730 km negligible LNGS Overburden : 3800 m.w.e. Cosmic muons flux : 1 m -2 hour -1 Roma OPERA 21/7/2007 G.Wilquet - EPS

12 τ - decay channels Signal and background events ν μ ν τ oscillation channel Signal (Δm 2 ) 2 Full mixing Δm 2 = 2.5 x 10-3 ev 2 Δm 2 = 3.0 x 10-3 ev 2 Background: Charm Hadron interaction Muon scattering τ - µ τ - e τ - h τ - 3h ALL years of data taking 19 Nominal beam intensity p.o.t. / year 1.35 kton target mass (25% reduction w.r.t. proposal) 21/7/2007 G.Wilquet - EPS

13 OPERA Discovery probability vs. Δm 2 Discovery probability (%) 4-σ evidence 3-σ evidence 5 years of data taking Nominal beam intensity: p.o.t. / year 1.35 kton target mass MINOS 90% C.L. SK 90% C.L. L/E analysis ( 10 ev ) Δm /7/2007 G.Wilquet - EPS

14 OPERA Subsidiary Physics Programme : Improve CHOOZ upper limit on sin 2 2 θ 13 <0.14 Possible subdominant interpretation of ν μ disappearance in the atmospheric sector (neglecting matter effects): [ ] [ ] Δm ev L km P ν ν = sin θ sin θ sin. μ e EGeV 2 sin θ Compatible with full ν mixing and small admixture in 2 μ ντ ν ν sin 2θ 13 < 014. Δ m = ev Inherent limitation : Intrinsic 0.9 % ν e background in ν μ beam 2 Δ m = ev 2.5x e 3 OPERA /7/2007 G.Wilquet - EPS

15 2006 CNGS run with empty target: time structure On-time event : ( ) t t + TOF < Δt LNGS SPS extract TOF = 244. ms Δ t = 10. 5μs extract Clocks synchronized by GPS New Journal of Physics 8 (2006) 303 August : pot during 13 days = 5 days nominal intensity November : pot during 25 hours interrupted by major water leak in beam reflector Extraction ms Δ t = 10. 5μs extract Δt (ns) from first extraction 319 beam events observed 300 expected from beam intensity Cosmic background in extraction gate : 10-4 Δt (ns) from time of nearest extraction 21/7/2007 G.Wilquet - EPS

view Side view Inside emulsion sheets doublet attached to the back of the

16 2006 CNGS run: details of a muon track from a CC event in the rock in front of OPERA In the electronic detectors Top view In the brick Top view Side view Side view Inside emulsion sheets doublet attached to the back of the brick base base emulsion sheet 1 sheet 2 21/7/2007 G.Wilquet - EPS

down going cosmic from front beam down going cosmic from back Vertical angle θ (degrees)

17 2006 CNGS run: angle w.r.t. horizontal All track-like events data : cosmic + beam absolute cosmic MC In-time with beam down going cosmic from front beam down going cosmic from back Vertical angle θ (degrees) Zenith angle (degrees) θ expected from beam geometry: 33. θ = 34. ± 03. New Journal of Physics 8 (2006) /7/2007 G.Wilquet - EPS

18 2006 CNGS run: using muon hits time information down-going Cosmic muons up-going 1 up-going cosmic muon (2 expected) Resolution = 10 ns Cosmic run down-going Cosmic muons up-going Muons from beam interactions v/c During August beam run: Beam + Cosmic v/c 21/7/2007 G.Wilquet - EPS

Electronic detectors status and commissioning All electronic detectors commissioned but 2 HP drift tubes layers to be commissioned in Summer

19 Electronic detectors status and commissioning All electronic detectors commissioned but 2 HP drift tubes layers to be commissioned in Summer RPC veto plane to be commissioned in Summer DAQ and slow control operational and being fine tuned. Target Tracker efficiency Cosmic; better for beam Trigger threshold : 1 p.e. <Noise rate /channel> 20 Hz 99% Cosmic; better for beam RMS 500μm 300μm after aligment SM1 HPT hits residuals (mm) Cosmic; better for beam Cured problems Spectrometer RPC efficiency SM2 21/7/2007 G.Wilquet - EPS % 90%

20 Commissioning: Brick geometrical quality and tracker to brick connection using cosmic rays Parallelism Emulsion sheet to sheet σ=14. mrad Alignment σ = 09. μm Precision required to measure p by CMS detect small angle 1-prong τ - decays rad μm Vertical track position difference between prediction by target tracker and measurement in emulsion. Prediction quality : efficient brick selection fast track finding in emulsion σ=3 mm mm 21/7/2007 G.Wilquet - EPS

21 Autumn 2007 CNGS Commissioning and Physics RUN 3 weeks of CNGS commissioning run + 3 weeks of physics run following June CERN SPSC recommendation If intensity as in August 2006 : pot/extraction (70% nominal) If extraction scheme as in November 2006: 3 double fast extraction per 36 s SPS cycle If typical 70 % efficiency of the machines complex If target filling programme as scheduled Target mass Beam intensity Events in bricks Charm events 505(37%) 615(46%) tons pot 10% nominal year 10 flux in /7/2007 G.Wilquet - EPS

22 Summary as Conclusions Electronic detectors commissioning completed during summer 2007 and performances according to specs. Target tracker to brick connection and brick intrinsic geometrical quality according to specs. Brick production rate reaching cruse speed and completion of target filling expected in phase with CNGS beam availability in run very useful rehearsal despite major early beam fault during November run. 6 weeks of beam run in autumn 2007 including 3 weeks of physics run: 180 events in bricks expected including 10 charm; full size test of the detector and the analysis chain. More will be learned on the EEC technique after wide variety of test runs during summer /7/2007 G.Wilquet - EPS

23 Reserve 21/7/2007 G.Wilquet - EPS

Tracks reconstruction and Vertex finding in an ECC Fully automated

resolution high efficiency high speed microscopes European Scanning

asynchronous DAQ software Scanning speed achieved ~ 20 cm 2 / h

stage movement Hard core algorithms Scanning speed achieved ~ 20 cm 2

24 Tracks reconstruction and Vertex finding in an ECC Fully automated scanning systems: Computer controlled and data base driven high resolution high efficiency high speed microscopes European Scanning System Japanese S-UTS Customized commercial optics and mechanics + asynchronous DAQ software Scanning speed achieved ~ 20 cm 2 / h Piezo-controlled objective lens movement allows high speed continuous stage movement Hard core algorithms Scanning speed achieved ~ 20 cm 2 / h R/D to reach ~ 60 cm 2 / h 21/7/2007 G.Wilquet - EPS Hard-coded algorithms

25 OPERA Subsidiary Physics Programme II : Atmospheric muons High energy charge ratio Muons multiplicity E μ underground : 300 GeV E μ surface cut-off : 1400 GeV 21/7/2007 G.Wilquet - EPS

2006 CNGS beam runs results August : 7.6 10 17 pot during 13 days = 5 days nominal intensity 10.5 μs 10.5 μs 50 ms Extraction scheme : 1 CNGS cycles per 16.

26 2006 CNGS beam runs results August : pot during 13 days = 5 days nominal intensity 10.5 μs 10.5 μs 50 ms Extraction scheme : 1 CNGS cycles per 16.8 s SPS super-cycle 2 fast extractions per CNGS cycle November : pot during 25 hours of run interrupted by major water leak in beam reflector Extraction scheme similar to final (LHC): 3 CNGS cycles distant by 6 s per 36 s SPS super-cycle 2 fast extractions per CNGS cycle 21/7/2007 G.Wilquet - EPS

27 2006 CNGS run: time vs. zenith angle events selection on time events all events MC cosmic background : 4 events Zenith angle (rad) 10% of events in beam direction peak correspond to no beam ejection entry in CNGS beam database. 21/7/2007 G.Wilquet - EPS

28 Target filling schedule bricks week prod. total total per week brick production bricks produced so far To be updated Current production rate: 2500 bricks/week Rate anticipated from 9/2007 : 3500 bricks/week Filling completion expected for end 4/2008 in phase with CNGS run period weeks week 21/7/2007 G.Wilquet - EPS

A. Chukanov On behalf of OPERA collaboration JINR, Dubna TAUP 2011, Munich, 5-9 september, 2011

A. Chukanov On behalf of OPERA collaboration JINR, Dubna TAUP 2011, Munich, 5-9 september, 2011 Outline OPERA experiment Event location procedure n t candidate Background estimation Conclusion 2 OPERA: