OPERA physics programme experimental concept first results with

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

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

Physics Programme: compelling evidences of neutrinos oscillation at all available sources: Sun, atmosphere, LBL reactors & accelerators Parameter space allowed by Super-K and excluded by CHOOZ and Palo Verde Parameter space allowed for solar neutrinos and by Kam. LAND L/E dependence of the measured to expected fluxes ratio of atmospheric nm by Super-K Parameter space for atmospheric neutrinos allowed by Super-K Parameter space allowed by K 2 K and MINOS No evidence yet of flavour APPEARANCE tagged by identification of l- emitted in CC interaction 21/7/2007 G. Wilquet - OPERA @ EPS 2007 3

OPERA Main Physics Programme: tag the n appearance in a n beam by identification Admitted dominant interpretation of n disappearance in the atmospheric sector (neglecting matter effects): 21/7/2007 G. Wilquet - OPERA @ EPS 2007 4

Design an experiment – CNGS and OPERA - able to tag the n appearance in a n beam by - identification <En> well above n CC threshold (6. 3 Ge. V) for decent cross-section • <En> / L not much different than m 2 for decent Posc • Massive target to collect enough events • High spatial resolution to resolve the - path length ≈ 1 mm • Very low background not to dilute the expected low signal - n - - n ~1 mm 21/7/2007 G. Wilquet - OPERA @ EPS 2007 5

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 n ● provides large mass and micron and mrad precisions ● quasi on-line analysis : bricks in which events have occurred are removed analysed on daily base - typically 25. Brick • 56 lead plates interleaved with 57 sheets of nuclear emulsion • 4 × 5 × 7. 5 cm, 8. 3 kg. • 10 X 0 21/7/2007 Tracks : series of aligned segments in emulsion layers G. Wilquet - OPERA @ EPS 2007 6

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

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

Brick exposed to 8 Ge. V e- m r ina li re P y Pion misidentification (%) Particle ID and kinematics in ECC : d. E/dx (grain counting) and Coulomb multiple scattering NN using d. E/dx CMS y r a n i m li re P Muon identification (%) 21/7/2007 G. Wilquet - OPERA @ EPS 2007 9

OPERA detector : Veto plane + 2 identical super-modules SM 1 SM 2 0. 68 kton ID, charge, p p/p < 25% Wrong charge < 0. 3% Target and Target Tracker (6. 7 m)2 Veto plane (RPC) High precision tracker ● 6 4 -fold layers of drift tubes 21/7/2007 ID, charge, p Instrumented dipole magnet ● 1. 53 T ● 22 XY planes of RPC in both arms ● Target : 77500 bricks, 29 walls ● Target tracker : 31 XY doublets of 256 scintillator strips + WLS fibres + multianodes PMT for Muon spectrometer (8× 10 m 2) • Brick selection • Calorimetry G. Wilquet - OPERA @ EPS 2007 10

CERN Neutrino beam to Gran Sasso L=730 km CERN Energy spectrum maximizes 730 km OPERA LNGS Beam contamination Overburden : 3800 m. w. e. Cosmic muons flux : 1 m-2 hour-1 Roma 21/7/2007 G. Wilquet - OPERA @ EPS 2007 11

Signal and background events n -n oscillation channel - decay channels Signal ÷ ( m 2)2 – Full mixing 2. 9 - e- 3. 5 - h- 3. 1 - 3 h ALL 21/7/2007 Charm m 2 = 2. 5 x 10 -3 e. V 2 m 2 = 3. 0 x 10 -3 e. V 2 Hadron interaction Muon scattering - µ Background: y r a n i 4. 2 0. 17 5. 0 0. 17 4. 4 0. 24 0. 9 1. 3 0. 17 10. 4 15. 0 0. 76 m i l e r P G. Wilquet - OPERA @ EPS 2007 12

Discovery probability (%) OPERA Discovery probability vs. m 2 4 -s evidence 3 -s evidence m li re ry a in P MINOS 90% C. L. SK 90% C. L. L/E analysis 21/7/2007 G. Wilquet - OPERA @ EPS 2007 13

OPERA Subsidiary Physics Programme : Improve CHOOZ upper limit on sin 2 2 q 13<0. 14 Possible subdominant interpretation of n disappearance in the atmospheric sector (neglecting matter effects): OPERA Preliminary ry eli 2. 5 x 10 -3 Inherent limitation : Intrinsic 0. 9 % ne background in n beam na mi Pr 0. 06 21/7/2007 G. Wilquet - OPERA @ EPS 2007 14

2006 CNGS run with empty target: time structure New Journal of Physics 8 (2006) 303 • August : 7. 6 1017 pot during 13 days = 5 days nominal intensity • November : 0. 6 1017 pot during 25 hours interrupted by major water leak in beam reflector Extraction 1 2 t (ns) from first extraction 319 beam events observed 300 expected from beam intensity Cosmic background in extraction gate : 10 -4 21/7/2007 G. Wilquet - OPERA @ EPS 2007 t (ns) from time of nearest extraction 15

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

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 -20 Vertical angle q (degrees) -10 0 10 20 Zenith angle (degrees) New Journal of Physics 8 (2006) 303 21/7/2007 G. Wilquet - OPERA @ EPS 2007 17

2006 CNGS run: using muon hits time information down-going r a n i lim e r P y Cosmic muons down-going y r a n i 21/7/2007 Cosmic run 1 up-going cosmic muon (2 expected) up-going Muons from beam interactions m eli Pr Resolution = 10 ns up-going During August beam run: Beam + Cosmic muons G. Wilquet - OPERA @ EPS 2007 18

Electronic detectors status and commissioning All electronic detectors commissioned but • 2 HP drift tubes layers to be commissioned in Summer 2007. • RPC veto plane to be commissioned in Summer 2007. Cosmic; better for beam y r a n i m li re P DAQ and slow control operational and being fine tuned. HPT hits residuals (mm) Cosmic; better for beam 95% Trigger threshold : 1 p. e. <Noise rate /channel> ≈ 20 Hz r a n i y SM 1 m li re P 90% SM 2 Cured problems y r a n i m li re P Target Tracker efficiency 21/7/2007 99% Spectrometer RPC efficiency G. Wilquet - OPERA @ EPS 2007 19

Commissioning: Brick geometrical quality and tracker to brick connection using cosmic rays Emulsion sheet to sheet Alignment Parallelism m eli ry a in Pr m li re Precision required to • measure p by CMS • detect small angle 1 -prong - decays ry a in P mm rad Vertical track position difference between prediction by target tracker and measurement in emulsion. Prediction quality : efficient brick selection fast track finding in emulsion 21/7/2007 G. Wilquet - OPERA @ EPS 2007 y r ina lim e Pr mm 20

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 : 1. 7 1013 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 505(37%) → 615(46%) tons Beam intensity 0. 43 1019 pot ≈ 10% nominal year ≈ 10 × flux in 2006 Events in bricks 180 Charm events 21/7/2007 10 G. Wilquet - OPERA @ EPS 2007 21

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 2008. • 2006 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 2007. 21/7/2007 G. Wilquet - OPERA @ EPS 2007 22

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

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 Customized commercial optics and mechanics + asynchronous DAQ software Scanning speed achieved ~ 20 cm 2 / h 21/7/2007 Japanese S-UTS 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 G. Wilquet - OPERA @ EPS 2007 Hard-coded algorithms 24

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

2006 CNGS beam runs results August : 7. 6 1017 pot during 13 days = 5 days nominal intensity 10. 5 s 50 ms Extraction scheme : 1 CNGS cycles per 16. 8 s SPS super-cycle 2 fast extractions per CNGS cycle November : 0. 6 1017 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 - OPERA @ EPS 2007 26

2006 CNGS run: time vs. zenith angle events selection on time events all events m eli MC cosmic background : 4 events ry a n i Pr 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 - OPERA @ EPS 2007 27

Probability of signal at 4 -s above background in n -n oscillation channel 90 % CL Sensitivity u p To u be s ma % 25 gma r fo 3 si d te nd a a d ed r s o cti n MINOS 90% CL Opera with 1. 5 beam upgrade and 30% background reduction Opera, with 1. 5 beam upgrade Opera with 30% background reduction Opera nominal SK 90% CL (L/E analysis) 21/7/2007 G. Wilquet - OPERA @ EPS 2007 28

Target filling schedule 27500 bricks produced so far d e t a • Rate anticipated from 9/2007 : 3500 bricks/week pd u e b o total per week • Current production rate: 2500 bricks/week T • Filling completion expected for end 4/2008 in phase with CNGS run period week 21/7/2007 G. Wilquet - OPERA @ EPS 2007 29