Esperimento OPERA Commissione II INFN Roma 28 Settembre 2010 CNGS beam Detector operation Run 2008, 2009, 2010 Richieste finanziarie S. Simone Università di Bari e INFN

OPERA: first direct detection of neutrino oscillations in appearance mode through the    channel following the Super- Kamiokande discovery of oscillations with atmospheric neutrinos and the confirmation obtained with solar neutrinos and accelerator beams. Important, missing tile in the oscillation picture. Requirements: 1) long baseline, 2) high neutrino energy, 3) high beam intensity, 4) large mass, 5) detect short lived  ’s L = 730 km CERN LNGS T flight = 2.44 ms Expected neutrino interactions for 22.5x10 19 pot: ~  CC + NC ~ 160 e + e CC ~ 115  CC (  m 2 = 2.5 x eV 2 )

Italy Bari Bologna LNF Frascati L’Aquila, LNGS Naples Padova Rome Salerno Japan Aichi Toho Kobe Nagoya Utsunomiya Belgium IIHE-ULB Brussels Croatia IRB Zagreb France LAPP Annecy IPNL Lyon IPHC Strasbourg Germany Hamburg Münster Rostock Israel Technion Haifa Korea Jinju Russia INR RAS Moscow NPI RAS Moscow ITEP Moscow SINP MSU Moscow JINR Dubna Switzerland Bern ETH Zurich Turkey METU Ankara The OPERA Collaboration 180 physicists, 33 institutions in 12 countries Tunisia CNSTN Tunis

CNGS YearBeam days Protons on target SPS Eff. Events in the bricks x % x % x10 19 (20 Sept.) 80%3167 (20 Sept.) 8558 events collected until 20/9/2010 High specific CNGS efficiency ~ 97% 2010: hoping to get as close as possible to nominal year (4.5x10 19 pot) Extrapolating average performance  get around 4.2 E 19 by the end of the run Days pot

Efficiency 79.5% Note: 80% efficiency is among the best records for the SPS

Unix time 2 E 13 pot/extraction Extraction 1 Extraction 2 MD MTE Stop Plateau depending on SPS RF performance 20/9/2010 7:00 2 E 13 pot/extraction

WHAT ABOUT RUN 2011 and RUN 2012 ??

 ~ 0.6 mm      - + X      (17 %) h -    n(      (50 %) e -    e  (18 %)          n    (14 %) “kink” “kink”topologies detector requirements: large mass, high resolution (for signal selection and background rejection) OPERA: looking for  4.5·10 19 p.o.t./year, 200 days/year for OPERA (~1.25 Kton) detector: ~ 4700  CC+NC / year ~ 30 e + e  CC / year ~ 25  CC / year (  m 2 = 2.5 x eV 2 ) expected neutrino interactions _   e e  h h   3htotal signal (  m 2 = eV 2 ) bkgd pot

OPERA: nuclear emulsions + electronic detectors OPERA: the hybrid solution ~ bricks in the OPERA target (~ 1.25 kton) 1 mm  Pb Emulsion layers 8.3 Kg (10.2*12.5)cm 2 1 emulsion film: 2 emulsion layers (44  m thick) poured on a 200  m plastic base when electronic detectors enter the game:  trigger for a neutrino interaction  muon identification and momentum/charge measurement 1 Changeable Sheet doublet (CS)/brick: two refreshed emulsion films,vacuum packed and glued onto the downstream brick face brick: 57 emulsion films sandwiched between 1mm Pb plates physics in a brick:  interactions and decay topology reconstruction  measurement momenta by MCS   e   separation  electromagnetic calorimetry CS

A. Ereditato - CERN - 4 June Pb emulsion layers   1 mm interface films (CS) ECC brick electronics trackers Massive active target with micrometric space resolution Detect tau-lepton production and decay Use electronic detectors to provide “time resolution” to the emulsions and preselect the interaction region Intense, high-energy muon-neutrino beam THE PRINCIPLE OF THE EXPERIMENT: ECC + ELECTRONIC DETECTORS

Target area Muon spectrometer SM1SM2SM1SM2 THE IMPLEMENTATION OF THE PRINCIPLE

Cosmics CNGS events Electronic Detectors data taking Continuous operation and cosmics data taking during all the year ~100% live time (apart few hours of power cuts and small accidents) Electronic Detectors analysis (paper in preparation): Events selection and external events background Muon identification NC/CC Muon momentum/charge measurement Hadronic showers measurement Cosmic ray studies

Interface emulsion films: high signal/noise ratio for event trigger and scanning time reduction ECC 10cm 2.6 cm 12.5cm Changeable Sheet (CS) T TT T Angular accuracy of the electronic predictions Position accuracy of the electronic predictions CS interface sheet

OPERA: steps to reach the goal on-line analysis of electronic data brick finding algorithm for events ‘on time’ with the beam remove brick and scan CS: the interface between brick and TT (  pos ≈ 10 mm,   ≈ 20 mrad) confirmation of the extracted brick development of the brick to be sent in a scanning Lab for ‘CS to brick connection’ (  pos ≈ 70  m,   ≈ 8 mrad), event location, decay search studies, etc.. [2009 JINST 4 P04018]

Brick candidate handling status September 22 nd 2010 : BMS extraction: 25 bricks/8 hour shift ~90’000 bricks handled until 2009 to extract ~7000 event bricks Operation time ~80% of the year Extraction of few tens blocked bricks

A. Ereditato - CERN - 4 June FILM DEVELOPMENT FACILITY 6 semi-automatic lines running in parallel, in dark maximum rate: 150 bricks/week additional facility underground for CS: max 300 CS/week

Development statistics (April 2010 – September 2010) ECC developed : 1153 ( 230 / month) Lack of requests August stop Mean Value

RUN : ECC development Christmas ‘08 Earthquake Christmas ‘09 Mean value : 40 ECC treated : 3537

Nagoya LNGS European Scanning System Super-UltraTrack Selector (Japan) CHANGEABLE SHEET SCANNING STATIONS CS scanning: 2 facilities  ~ 200 cm 2 emulsion film surface /hour/facility s: precision mechanics, stepping motors, CCD readout, pattern recognition, image analysis,… A. Ereditato - CERN - 4 June

Bricks Scanning Distributed on 12 Labs Concurrent activities: Vertex location Decay Search (D.S.), since Dec Scan-forth (Bck. measurements, min. bias kinematics) 9m done. Goal  100m scanned track length in 1.5 years Special measurements on decay candidates: large volumes, showers, kinematics, tracks follow-down, re-measurements

Shift activity for the Opera Run Electronic detector shifts : 3+1 (on call) people Scanning Station Shifts (Changeable Sheet measurements): 6 people = 3 shifts / day, 2 people /shift Brick handling Shift: 5 people + firm Development laboratories : 8 people, single shift Brick Measurements in the group laboratories

Event location summary for 2008 run 0mu1muAll Events predicted by the electronic detector Found in CS Located in ECC Located in dead material Interactions in the upstream brick63945 Decay search performed Decay search completed for 90.4% of the sample

Overall efficiency using 2008 run (completed) EventsAll0µ1µ Triggers Interactions in the bricks Reject bad quality CS films 0.94 Brick identification by electronic detectors Location fraction Located interactions % and 76% for 0µ and 1µ events

Status of event location for 2009 run (events location in progress ) 0mu1muAll Events predicted by the electronic detector Extracted CS CS Scanned Found in CS Located in ECC Located in dead material Interactions in the upstream brick Decay search performed Decay search completed for 61.3% of the located events

Status of event location for 2010 run 0mu1muAll Events predicted by the electronic detector Extracted CS CS Scanned Found in CS Located in ECC193958

Sharing of results 2367 located interactions 1268 in Europe, 1099 in Japan Japan 46.6%, Italy 35.7 % Switzerland 17.7%

GLOBAL ANALYSIS PERFORMANCE

OPERA: analysis performances (I) IP distribution for  events (MC) IP distribution for:   events (MC) NC+CC  events (MC), NC+CC  events (Data) expanded scale mm Ip measurement: particles momenta measurements by MCS P rec (GeV) P beam (GeV)  = (22±4)%

 detection and  0 mass reconstruction E = 0.5 GeV E = 8.1 GeV 2 em showers give a reconstructed mass 160±30 MeV/c2 EM shower energy measured by shower shape analysis and Multiple Coulomb Scattering method   e-pair e+ e-  70% of 1-prong hadronic  decays include one or more  0  importance of gamma detection Gamma detection: how to… detection of shower detection e-pair at start point 1  mass resolution: ~ 45% OPERA: analysis performances (II)

charm decays inside the OPERA target Decay search procedure defined (ip evaluation, small angle kink search, extra-tracks search) Decay Search extensively applied to located interactions data sample Charm topology analogous to  : reference sample for the decay finding efficiency 4 mm kin k x-view 1ry vertex 1.3 mm 1ry  daughter  flight length: 1330 microns kink angle: 209 mrad IP of daughter: 262 microns daughter muon: 2.2 GeV/c decay Pt: 0.46 GeV/c charm candidate (dimuon) 18 charm candidate (by kinematical cuts) 3 of them with 1-prong kink topology. Expected: 15.5 ± 2.8 out of which 0.79 ± 0.22 with kink topology Expected BG: 1.7 events (loose cuts: work in progress to reduce BG) D 0 hypothesis: F.L.:  m,  : , invariant mass: 1.7 GeV D0 hypothesis

e candidate event From a subsample of ~ 800 located events we detected  e candidates Additional physics subject: study  - e oscillations

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OPERA: the first  candidate event (I) Physics Letters B 691 (2010) Muonless event ED display zoom to the selected brick CS confirmation of the brick Scan-back in the brick for stopping point definition CS predictions Large area scanning Full reconstruction of vertices and gammas

Distance from 2ry vertex (mm) Energy (GeV) IP to 1ry vertex (  m) IP to 2ry vertex (  m) Prob. of attach. to 1ry vtx* Prob. of attach. to 2ry vtx* Attachment hypothesis 1 st  ± 1.0 ± < ry vertex 2 nd  ± 0.4 ± ry vertex (favoured) OPERA: the first  candidate event (II) The primary neutrino interaction consists of 7 tracks of which one exhibits a visible kink Two electromagnetic showers caused by  -rays, associated with the event, have been located (total radiation length downstream the vertices: 6.5 X 0 ) * probability to find an IP larger than the observed one none of the tracks is compatible with being an electron track for tracks 1, 5 and 6 P(  ) < (p-range consistency check) remaining tracks are hadrons (interaction seen) residual probability of  CC event (possibly undetected large angle muon) is ≈ 1%.

OPERA nominal analysis flow applied to the hadronic kink candidates: (more refined selection criteria being developed were not considered here not to bias our analysis) kink occurring within 2 lead plates downstream of the primary vertex kink angle larger than 20 mrad daughter momentum higher than 2 GeV/c decay Pt higher than 600 MeV/c, 300 MeV/c if ≥ 1 gamma pointing to the decay vertex missing Pt at primary vertex lower than 1 GeV/c azimuth angle between the resulting hadron momentum direction and the parent track direction larger than  /2 rad ANALYSIS Kinematical analysis

OPERA: the first  candidate event (III) Kinematical variables are satisfying all selection criteria for hadronic kink  first  candidate ! defined in the proposal candidate to the  1-prong hadron decay mode invariant mass of  -rays 1 and 2: 120 ± 20 (stat)± 35(syst) MeV/c 2 supporting the hypothesis  0   assuming the charged decay product as  -, the invariant mass of  - and 2 gammas: MeV/c 2 compatible with the  (770) mass VARIABL E AVERA GE* kink (mrad)41 ± 2 decay length (  m) 1335 ± 35 P daughter (GeV/c) Pt decay (MeV/c) missing Pt (MeV/c) ϕ (deg)173 ± 2 *assuming both  1 and  2 attached to 2ry vertex (uncertainty on Pt due to the alternative  2 attachment is < 50 MeV/c ) 2ry vtx compatible with   h  n    

OPERA: the first  candidate event (IV) Evaluation of background sources: prompt  ~ /CC decay of charmed particles produced in e interactions ~ /CC double charm production ~ /CC decay of charmed particles produced in  interactions ~ /CC hadronic reinteractions (UPDATE wrt Proposal) ~ /CC for the 1-prong hadronic channel 0.007±0.004 (syst) background events are expected for the analyzed statistics - Background evaluation by using state-of-the-art FLUKA code (upgrade wrt Proposal) - Kink probabilities integrated over the μ NC hadronic spectrum yield (same cuts as for the tau analysis) a BG probability of (1.9 ± 0.1) x kinks/NC (2 mm Pb) - First cross-checks of the simulation were performed on a scan-forth tracks sample and on dedicated test-beam data, showing a good agreement with the simulation, although still statistically limited

OPERA: the first  candidate event (V) Background expectations 1-prong hadron  decay channel: (~ 50% syst. error for each component) events (reinteractions) events (charm, assuming standard mu ID) ± (syst.) events 1-prong hadron BCK for all decay modes: 1-prong hadron, 3-prongs + 1-prong μ + 1-prong e : ± (syst.) events total BG Background fluctuation probabilities to 1 event: 1-prong hadron channel only: P=1.8%  2.36  significance All tau decay modes included in search: P=4.5%  2.01  significance

RICHIESTE FINANZIARIE