The OPERA long baseline neutrino experiment : status and first results.

1. The OPERA long baseline neutrino experiment : status and first results. Magali Besnier Laboratoire d’Annecy-le-Vieux de Physique des Particules On behalf of the OPERA collaboration LLWI 08 - february 21st 2008

2. OPERA 37 INSTITUTS, ~160 PHYSICISTS International Collaboration (Europe + Asia) IIHE (ULB-VUB), Brussels Sofia IHEP Beijing, Shandong IRB Zagreb LAPP Annecy, IPNL Lyon, IRES Strasbourg Berlin Humboldt, Hagen, Hamburg, Münster, Rostock Technion Haifa Bari, Bologna, LNF Frascati, L’Aquila, LNGS, Napoli, Padova, Roma La Sapienza,Salerno Aichi, Kobe, Nagoya, Toho, Utsunomiya INR Moscow, ITEP Moscow, JINR Dubna, Obninsk Bern, Neuchâtel, Zurich METU Ankara Possibility of nmneoscillation search for q13 measurement First direct observation of nmnt oscillation Oscillation ProjectwithEmulsiontRackingApparatus Search for tauneutrino appearance at Gran Sasso laboratory in a pure muonneutrinobeam produced at CERN (732 km)

3. 700 m 100 m 1000m 67 m vacuum 4.5 1019 p.o.t. /year Decay tube vacuum tests successful target Muon chambers Hadron stop Horn CNGS beam (CERN Neutrino to Gran Sasso) To Gran Sasso 400GeV Ø at GS=2km 3.2° angle Civil engineering completed (June ’03) Hadron stopper and decay tube installed (June ’04) Target section completed in 2006 (first CNGS beam in August 2006)

4. CNGS beam (CERN Neutrino to Gran Sasso) 4.5 1019 p.o.t. /year nmFlux at Gran Sasso (given by Fluka) Number of expected events at Gran Sasso (0-100 GeV): (before reconstruction and detection efficiencies) N nm CC= 3000/yr/kton N neCC= 20 /yr/kton N nt CC= 14 /yr/kton P(nm->nt)*s(nt CC) Dm223= 2.5 10-3 eV² nm flux  appearance signature .Detection of  CC interaction and direct observation of decay topology .High background rejection tdecay kink t • t-m- nt nm (17.4%) • t-e- nt ne (17.8%) • t-h-nt n(po) (49.5%) • t-p+ p- p-nt n(po)(14.5%) ~ 0.6 mm nt

5. OPERA Performances fornmnt oscillation Reconstruction efficiency % Back-ground channel Total 0.75 14.9 11.06 10.4 4-s evidence 3-s evidence full mixing, 5 years run @ 4.5x1019 pot / year Number of expected signal and background events OPERA Discovery probability vs. Dm2 Most important background : charm particle production Best value ofDm223= 2.5 10-3 eV² 3s range : 1.9 - 3.2 10-3 eV² T.Schwetz, hep-ph/0606060 4s Discovery probablility > 90% for Dm223>2.5 10-3 eV² Discovery probability (%) 0 20 40 60 80 100 3s range 0 .05 0.1 0.15 0.2 0.25 0.3 0.35

6. m spectrometer: Dipolar magnet + RPC chambers B=1.6 T Hall B n Precision tracker: Drift tubes ICARUS(CNGS2) brick (56 Pb/Em. “cells”) BOREXINO Hall C OPERA (CNGS1) 8 cm (10X0) module Target Trackers Pb/Em. target 2 super modules 1 super module = 29 walls + 31 Target Tracker + 1 muon spectrometer (22 RPC planes + 6 drift tube planes) 52*51 bricks/wall brick wall 154 750 bricks 1.35 kton lead target ~4000 nmCC/yr scintillator strips p/p < 20% for E<50GeV OPERA detector at LNGS (Notional Laboratory of Gran Sasso, Italy, 120 kms from Rome) rock thickness 1400m (3800 m.w.e.) cosmic muon flux: 1/m2/h LNGS-INFN

7. OPERA bricks : main target detector component Emulsion Cloud Chamber (ECC) :1 ECC brick = 56 sheets Pb + 57 photographic emulsions 300µm emulsion films and 1mm thin lead foils by Fuji Film (Japan) JLGoslar (Germany) 1 mm t n 2 emulsion layers(45 m thick)poured on a210 m plastic base Pb MC ntt3h Emulsion layers Résolution (microtracks) spatial : 0.06 µm Angular : ~ 2 mrad This technology allows a few micron spatial resolution, and a 3D reconstruction of particle tracks, necessary fortdetection 10.2cm 2mm 12.5cm Vertex position resolution : ~1µm in transverse plane The most precise tracker 6mm - Measurement of hadrons momenta by MCS - dE/dx pion/muon separation at low energy - Electron identification and energy measurements for electrons and photons 14 mm Reconstructed electronic shower 14 mm n 8 cm 12.5 cm 10 cm 8.6 kg

8. BAM(Brick Assembling Machine) 5 articulated robots Automatic lead/emulsion piling in a dark room (~700 bricks/day) The BMS(Brick Manipulator System) one robot on each side of the detector Insertion and extraction of bricks following intelligent procedures. Begining 2007 now Target preparation 2003 : start building detector June 2008 : end of filling target now

9. Detector today : electronics fully instrumented and tested Brick filling on the way : 99000 Bricks already inserted LNGS Hall C

10. OPERA event analysis procedure Brick finding : selection of the interaction brick provided by time correlation of electronic detectors Emulsion Development of candidate bricks at Gran Sasso (surface facilities)  31 tracking scintillator planes (TT)/super modules Emulsion shipment Trigger(>99%) +Brick finding(7090%) Emulsion Scanning with automated microscopes : 10 laboratories in Europe and Japan Example of a vertex in emulsion p.h. 0 max 20-30 bricks extracted / day

11. Scanning : emulsion digitisation Field of vue 16 tomographic images = 45µm 300µm 300µm 2D images processing 3D reconstruction of particle tracks 2 emulsion sides (45 mm) speed : 20cm²/hour/emulsion side Résolution (grains) spatial : 0.06 µm Angular : ~ 2 mrad 1 plastic base (200 mm) 1 emulsion sheet (2 sides) : 12h scanning - ~5GB Reconstruction of micro-tracks (45µm) 10 scanning laboratories in Europe and Japan

12. First OPERA results with CERN neutrino beam Beam events cosmics Positive electronic tests during first beam run (August 06 : 0.084 1019 integrated pot) ninteraction in magnet (Fe) • More than 300 registred events correlated in time with beam : interactions inside the rock and inside the detector (TT and spectrometers) First events from the CNGS neutrino beam detected in the OPERA experiment R. Acquafredda et al 2006 New J. Phys. 8 303

13. Muon track inside emulsions First OPERA results with target bricks from cosmic run < 1 event per day inside the acceptance ! ~20 ‘good’ muons per month April 17th- May 15th 2007 : 30 bricks extracted 28 muons found in emulsions Cosmic muons in OPERA detector (ray bandle) 45 µm 210 µm • Mean prediction accuracy (ED-brick): • Δx = 11 mm (along the tray) • Δy = 14 mm (vertical direction) • Δθx = 6.0 mrad • Δθy = 3.3 mrad These first data have confirmed the good accuracy of the ED predictions and validated the analysis chain

14. First OPERA results with target bricks from CNGS run (SM1 filled at 80%) Nominal intensity :4.5 1019 pot /yr (1yr=200 days) CNGS integrated intensity from September 24th to October 20th : 8.24 1017 pot 20/10/07 12/10/07 Comissioning Physics Problems in ventilation control units of the proton target 9/10/07 6.72 1017 pot 59 : CNGS very stable at 1.58 1017 pot/day 326 expected events in bricks 38 events registered during the 2007 CNGS run : 29 CC 9 NC Expected 75% CC and 25%NC proportions 5/10/07 3.91 1017 pot

15. Bologna scanning laboratory 1 cm First OPERA neutrino event located in brick (October 2nd 2007) nµCC Hadronic shower m- muon nµ Hadronic shower Em=7.8 GeV n 12/29 located in bricks so far 18 m

16. Nagoya scanning laboratory nµ nµ Hadronic shower n 2 cm nµ NC Hadronic shower 3/9 located in bricks so far 18 m

17. Conclusion • OPERA is the first experiment for nt appearance in a nm beam • Hybrid detector with passive lead target and active electronic detectors • Electronic parts fully commissioned • 0.9 kton (99000 Bricks) already inserted in the detector • First results • CNGS beam run in August 2006 : electronic detectors gave good results • Cosmic run : brick candidate extraction ; scanning and analysis have validated the full analysis chain • Neutrino events have been observed in OPERA bricks during the CNGS beam run of 2007. Location and reconstruction of neutrino vertex in emulsions was an important learning phase. Analysis is on the way. • Future • Next CNGS beam run with full target completed expected by june 2008 ~20 neutrino interactions / day  1stt event expected

19. CNGS beam @ CERN: Proton extractions from SPS with 3 cycles of 6s each : 2 extractions of 10.5 ms, separated by 50 ms. time ~1extraction Beam event selection : TOPERA – (TSPS + TOF) < Tgate ~2.4ms Nominal intensity :4.5 1019 pot /yr, with 2.4 1013 pot/extraction (FE)

20. Control of the neutrino beam direction: With the horizontal profile of the CNGS muons in the 2 muon detectors 1st muon chamber 2nd muon chamber p m, nm >1km 67m - First muon detector : ≤ 2.5 x 107 muons / cm2 / 1013 pot - Second muon detector :  ≤ 4 x 105 muons / cm2 / 1013 pot

21. CERN-LNGS time correlation All events within a window of +- 20 ms since the beginning of the extraction Extraction 1 Should start at 0 and last up to 10500 µs.  New calibrations will be done with a new GPS system receiver and a Cs clock of 1ns accuracy. ns Extraction 2 ns

22. Target chamber • Solution : • Replace damaged electronics • Find another place for ventilation control units These doses were computed by the Fluka group and known since many years !! They were not just taken into account when the ventilation was installed Radiation protection measurements confirm the calculations

23. 1.7 m 6.9m 64 strips/module 2 x 256 strips LNGS Tracker wall Target Tracker ●Trigger: > 99% ●Brick finding :  7080% ● Initiate muon tagging Plastic scintillator strips (AMCRYS-H, 6.7m x 2.6cm x 1cm) readout by Kuraray WLS fibres + Hamamatsu PMT’s (64 channels) Reconstructed cosmic track

24. Muon spectrometer coil M ~ 950t 12 Fe slabs (5cm thick) 8.2 m B= 1.55 T 2 cm gaps slabs RPC’s base Drift tubes Inner Tracker: 11 planes of RPC’s 21 bakelite RPC’s (2.9x1.1m2) / plane Precision tracker: 6 planes of drift tubes diameter 38mm, length 8m 4 staggered layers / plane, each layer consisting of 168 tubes efficiency: 99% space resolution: 300µm  identification:  > 95% (TT) p/p < 20% , p < 50 GeV/c misidentified  charge prob.  0.1  0.3%

25. PEANUT : OPERA test-beam at FERMILAB goal : to observe neutrino interactions in OPERA bricks Detector placed in the front of the MINOS near detector: -4 walls of 3*4 OPERA bricks exposed to NUMI beam (nm ) in « low energy » configuration (<E>=10GeV, Epeak=3GeV ) -DONUT SFT (scintillators) between each wall Brick piling in dark room 5 nm events/brick /day expected bricks exposed ~20days Exposure time: October 18th 2005 -> Mars 1st 2006 total 160 Bricks made, exposed and developped developper SFT-emulsions alignment Neutrino reconstruction in emulsions ~500µm spatial resolution ~5mrad angular resolution Salerno scanning lab analysis

26. m232 = 2.5 x 10-3 eV2 23 = 45° nominal CNGS beam 5 years Combined fit of Ee, Evis, (pt)miss 2.5x10-3 eV2 sin2(213)<0.06 13 < 7.1º   eoscillation search 90% C.L. limits on sin2(213) and 13 :