Activités OPERA au LAPP

Activités OPERA au LAPP

Latest results from the OPERA experiment D. Duchesneau, LAPP/CNRS, Universit Savoie Mont-Blanc On behalf of the OPERA Collaboration Introduction Experimental setup: CNGS and detector Data Analysis and Oscillation results nt appearance nm disappearance ne appearance search Conclusions July 4th 2016 1 The OPERA collaboration ~ 140 physicists, 26 institutes, 11 countries Belgium IIHE-ULB Brussels Croatia IRB Zagreb France LAPP Annecy IPHC Strasbourg Germany

Hamburg Israel Technion Haifa Italy Korea LNGS Assergi Bari Bologna LNF Frascati Naples Padova Rome Salerno Jinju Japan Switzerland Aichi Toho Kobe Nagoya Nihon Russia

INR RAS Moscow LPI RAS Moscow SINP MSU Moscow JINR Dubna Bern Turkey METU Ankara July 2000: Experiment proposal May 2003: start construction at LNGS summer 2006: 1st run with cosmics and CNGS commissioning autumn 2007: CNGS beam commissioning: n interactions seen in the OPERA target July 2008: Emulsion target completed: start of n physics run 2 CNGS/OPERA: European long baseline n project: motivated by the atmospheric n disappearance results and the evidence of neutrino oscillation in 1998 3-flavour oscillation formalism (PMNS matrix) describes with success the major results from solar, atmospheric, reactor and neutrino beam experiments Many results from n disappearance (ne, nm, nnm, nne) => Oscillation picture should be tested in different n flavour appearance mode In the CERN high energy nm beam (CNGS): 2 mm23 L

P( t ) cos ( 13 ) sin ( 2 23 ) sin ( 1.27 ) E 2 4 73 0 search for direct nt appearance at the Gran Sasso underground laboratory (730 km from CERN) 2 km LNGS by-product analysis: search for nm ne and put constraints on non standard oscillation 3 CNGS: CERN Neutrinos to Gran Sasso P(n n) 1.7% n to Gran Sasso L=730 km Conventional n beam: 400 GeV protons from SPS

2 fast extractions (10.5 ms), separated by 50 ms / SPS cycle (6 s) => 2 1013 protons/extraction => Average beam power: 160 kW (peak: 480 kW) < E >n 2012 p.o.t. (1018) 2011 0.9 % / nm CC 2.1 % CC nt prompt 2009 Record performances in 2011 date 17 GeV (ne + ne)CC / CC / nmCC nm 2010

2008 nm flux optimized to maximize the nt charged current interactions negligible CNGS operation: 2008 => 2012 total intensity delivered: 1.8 x1020 p.o.t. 4 LNGS: Gran Sasso National Laboratory ( Italy, 120 km from Rome) Underground laboratory: 1400 m good cosmic ray shielding 1 cosmic m/m2/hr 3 large experimental halls (100 m x 20 m x 18 m) directed towards CERN 3800 mwe ICARUS Hall B N CER t ri n eu

HallC nos Borexino OPERA 5 g . ct < 1 mm nt t p, e, m Experimental signature for nt appearance: ne nm nt t decay modes: m- nt nm h- nt npo e+- n- t - ne h h h nt npo p,n,p,K... BR 17.4 % .4 % 49.5 %

17.4 % .8 % 15.2 % detect and identify the nt charged current (CC) events OPERA principle: hybrid detector with modular structure direct observation of t decay topology mm resolution: photographic emulsions large target mass: alternate emulsion films and lead sheets reject main topological background: charm production good muon id and charge reconstruction: use electronic detectors also for trigger and event localisation 6 1.25 kton detector at Gran Sasso (Hall C) SM2 SM1 2 identical Super Modules (SM) Veto plane (glass RPC) JINST 4(2009) p04018 7 1.25 kton detector at Gran Sasso (Hall C) SM2 SM1 2 identical

Super Modules (SM) Veto plane (glass RPC) Target and Target Tracker (6.7m)2 Target : 74500 bricks, 26 walls Target tracker : 31 XY doublets of 256 scintillator strips + WLS fibres + multianodes PMT JINST 4(2009) p04018 7 1.25 kton detector at Gran Sasso (Hall C) SM2 SM1 2 identical Super Modules (SM) Veto plane (glass RPC) Target and Target Tracker (6.7m)2 Target : 74500 bricks, 26 walls Target tracker : 31 XY doublets of 256 scintillator strips + WLS fibres + multianodes PMT JINST 4(2009) p04018 High precision tracker Instrumented dipole magnet 6 4-fold layers of 1.53 T drift tubes

22 XY planes of RPC Muon spectrometer (89 m2) 7 1.25 kton detector at Gran Sasso (Hall C) SM2 SM1 2 identical Super Modules (SM) Veto plane (glass RPC) Target and Target Tracker (6.7m)2 Target : 74500 bricks, 26 walls Target tracker : 31 XY doublets of 256 scintillator strips + WLS fibres + multianodes PMT Dp/p (<25 GeV/c) ~20% m ID (with TT) JINST 4(2009) p04018 ~95% High precision tracker Instrumented dipole magnet 6 4-fold layers of 1.53 T drift tubes

22 XY planes of RPC Muon spectrometer (89 m2) 7 OPERA target: Modular detector: basic unit brick 56 Pb plates (1mm) + 57 FUJI emulsion films +1 changeable sheet doublet (CS) plastic base 200 mm thick 8.3 kg 10X0 10.2cm n 12.5cm 10cm 12.5cm 8cm Track segment resolution: s (angle) = 2.1 mrad s (position) = 0.21 mm Prec (GeV) Measurement of particle momentum by Multiple Coulomb Scattering in lead NJP 14 (2012) 013026 OPERA

9 8 7 6 5 4 3 2 1 emulsion layers (44 mm thick) OPERA nt events (MC) NC+CC nm events (MC) NC+CC nm events (Data) m p test beam 1 2 3 4 5 6 7

8 Pbeam (GeV) Vertex position resolution : ~1m in transverse plane 8 OPERA event analysis nm charged current-like 20 m Beam on time event DAQ: trigger, selection Electronic detector reconstruction 9 OPERA event analysis nm charged current-like 20 m Beam on time event DAQ: trigger, selection Electronic detector reconstruction Brick Finding 2m 9

OPERA event analysis nm charged current-like 20 m Beam on time event DAQ: trigger, selection Electronic detector reconstruction CS film beam view Brick Finding 2m CS scanning and brick validation Send brick to development Emulsion scanning 0.02 m 9 Interaction location and vertex reconstruction Emulsion analysis: 40 automated microscopes in Japan in Europe Volume scan (~2 cm3) around each stopping point JHEP 11 (2013) 036 OPERA

1 cm n Scan about 10 films around vertex: Track reconstruction in several films Interaction location and vertex reconstruction Emulsion analysis: 40 automated microscopes in Japan in Europe Volume scan (~2 cm3) around each stopping point JHEP 11 (2013) 036 OPERA 1 cm n Scan about 10 films around vertex: Track reconstruction in several films Reject passing-through and short tracks Interaction location and vertex reconstruction Emulsion analysis: 40

automated microscopes in Japan in Europe Vertex location efficiency: Volume scan (~2 cm3) around each 74% CC stopping point 48% NC JHEP 11 (2013) 036 OPERA 1 cm n Scan about 10 films around vertex: Track reconstruction in several films Reject passing-through and short tracks Search tracks pointing to an interaction vertex Decay Search procedure Data sample total intensity collected: 17.97x1019 p.o.t.

Year Protons on target SPS Eff. Beam n days interactions 20% less than the experiment proposal value (22.5x1019 p.o.t.) 2008 1.74x1019 61% 123 1931 etrigger= 99% 2009 3.53x1019 73% 155

4005 2010 4.09x10 19 80% 187 4515 2011 4.75x1019 79% 243 5131 2012 3.86x1019 82% 257

3923 106 422 on time events recorded 60% are external rock events 20% are spectrometer interactions 19505 recorded n interactions in the OPERA target 83% are reconstructed in the target Event classification Performed analysis # of Decay Searched events 0m 1st+2nd brick 1144 1m (Pm < 15 GeV) 1st+2nd brick 4264 All 5408

P distribution for 1 m sample 11 Charmed hadron production (D0 4 prong) Charm topology similar to t (decay modes and lifetime) but m at interaction vertex Control sample for decay search and e Background, mostly from hadronic interactions Topology 2008-2010 data analysis Eur.Phys.J. C74 (2014) 2986 Impact parameter OPERA (kink) Observed events

Charged 1-prong Neutral 2-prong Charged 3-prong Neutral 4-prong Total Decay length 19 22 5 4 50 Charm 21 2 14 1 41 0.9 0.2 403 OPERA Expected events Background Total 93 30 4 41 18 2 1.0 0.3 5 1

<0.1 0.9 0.2 143 544 Angle in the transverse plane between and parent OPERA 12 oscillation analysis: nm,ee Background CC charm production (4% of CC), with mis-idd (similar lifetime, missing ET decays) D+ nm m- Large-angle coulomb scattering of nuclear interactions of hadrons (0.2% of NC)

nm m-,eem+ e+ h+ nm 13 oscillation analysis: nm,ee Background CC charm production (4% of CC), with mis-idd (similar lifetime, missing ET decays) D+ nm m- Large-angle coulomb scattering of nuclear interactions of hadrons (0.2% of NC) nm

m-,eem+ e+ h+ nm Kinematical analysis variables to reduce background: Missing pT at primary vertex F = angle of wrt hadronic shower in transverse plane to beam Flight length Total pT of daughters wrt direction pmissT zdec Emulsion film p2ryT p2ry m Transverse plane kink

lH pmissT : vectorial sum of the transverse momenta of primaries (except the parent) and daughters wrt beam direction p2ryT : transverse momentum of the daughter wrt the parent direction 13 nt events observed in OPERA EPS-HEP 2015, Vienna G.Sirri - INFN Bologna 14 Fifth nt candidate => discovery of nt appearance OPERA t- h- nt Phys. Rev. Lett. 115 (2015) 121802 VARIABLE VALUE Kink angle (mrad) 90 2

decay length (m) 634 30 P2ry (GeV/c) 11+14-4 Pmisst (GeV/c) 0.30.1 (degrees) 151 1 15 oscillation analysis results: Decay channel Expected background Had. Reinteraction Charm t 1h t 3h t t e Total

0.0170.003 0.170.03 0.0040.001 0.030.01 0.220.04 Large m scattering 0.0220.006 0.0030.001 0.00020.0001 0.020.01 0.00020.0001 psum : scalar sum of the momenta of all particles measured in the emulsion films 1,e 4,e 5: t 1h 2: t 3h 3: t m Total 0.040.01 0.170.03 0.0040.001 0.030.01 0.250.05 expected signal events Observed 2

Dm = events 2.4410-3 eV2 0.520.10 0.730.14 0.610.12 0.780.16 2.640.53 3 1 1 0 5 Probability to be explained by background fluctuation p = 1.1x10-7 No oscillation hypothesis excluded at 5.1 s Dm232 = 3.3 x 10-3 eV2 with a 90% confidence interval [2.0, 5.0] x 10-3 eV2 (assuming full mixing) Probability of observing 5 candidates (2.9 S+B events expected): 17% Frequency of configurations being less probable than the observed one: 6.4% 16 n event with 3 vertices Muonless event A primary and two secondary vertices found in emulsion, Electromagnetic activity (gs) at the kink point.

17 n event with 3 vertices Muonless event A primary and two secondary vertices found in emulsion, Electromagnetic activity (gs) at the kink point. Flight lengths: II: 103 mm III: 1160 mm Invariant massses at both secondary vertices are larger than 1 GeV. Event not classified as nt interaction candidate by standard analysis. Ad hoc simulations and multivariate analysis performed to distinguish between possible interpretations. 17 n event with 3 vertices Muonless event A primary and two secondary vertices found in emulsion, Electromagnetic activity (gs) at the kink point. Flight lengths: II: 103 mm III: 1160 mm

Invariant massses at both secondary vertices are larger than 1 GeV. Event not classified as nt interaction candidate by standard analysis. Ad hoc simulations and multivariate analysis performed to distinguish between possible interpretations. More details will be given at ICNFP 2016 PR EL IM IN AR Y 17 nm disappearance OPERA Full data sample (2008-2012) Use of electronic detector data only and separation between CC and NC like events ne interaction

a fit using NC-like/CC-like ratio in which all mixing parameters are fixed to the PDG values but Dm232 energy deposited in the scintillator planes reweighting MC according to oscillation probability and minimizing c2 between MC and data To reduce systematic effects coming from the beam uncertainty (no near detector), NC like over CC like ratio is used systematics under study Preliminary measurement of Dm232 consistent with the world average and the internal OPERA appearance results see also poster P1.035 from Budimir Kliek 18 OPERA ne appearance search 2008-2012 sample (17.97 x 1019 p.o.t.) ne interaction

Observed 34 e events Expected e events : e beam contamination 36.7 5 Background e + mis-idd 0 1.2 0.1 From 3-flavour oscillation: e 2.9 0.4 evts (sin2(213) = 0.098) edet= eloc x eelectron_ID PR EL IM IN AR Y Numbers are preliminary. To increase signal-to-background ratio: E < 30 GeV 13 observed events for 9.2 1 background expected + 1.4 0.2 (from e) => Work in progress to extract exclusion limits on sterile search 18 sterile neutrino search appearance probability modified by one possible extra (sterile) state (3+1 scheme) e 2008+2009 data:

JHEP07 (2013) 004 Upper limit on non standard oscillations sin2(2new) < 7.2 x 10-3 90% CL where P = sin2(2new) sin2(1.27 mm2new L/E) Analysis to be updated with full ne sample and 3+1framework Observed 5 t events with 0.25 0.05 background expected - 90% CL exclusion region on Dm241 lowered down to 10-2 eV2 for sin2(2mt) > 0.5 - At large Dm241 : sin2(2mt) < 0.119 at 90% CL Update of JHEP 1506 (2015) 069 20 Summary and outlook OPERA has recorded events corresponding to 18.0 x 1019 p.o.t. delivered by the CNGS beam from 2008 to 2012 (80% of the nominal) Scanning (second data-taking) and analysis mostly completed! oscillation analysis: 5 candidates observed for 0.25 background expected => discovery with 5.1 s significance (PRL 115 (2015) 121802) => Dm232 = 3.3 x 10-3 eV2 with a 90% confidence interval [2.0, 5.0] x 10-3 eV2

disappearance analysis: => preliminary Dm322 consistent with world average e oscillation search: Number of events observed in agreement with expected background + standard oscillation Sterile oscillation constraints from ne and nt studies 21 Summary and outlook OPERA has recorded events corresponding to 18.0 x 1019 p.o.t. delivered by the CNGS beam from 2008 to 2012 (80% of the nominal) Scanning (second data-taking) and analysis mostly completed! oscillation analysis: 5 candidates observed for 0.25 background expected => discovery with 5.1 s significance (PRL 115 (2015) 121802) => Dm232 = 3.3 x 10-3 eV2 with a 90% confidence interval [2.0, 5.0] x 10-3 eV2 disappearance analysis: => preliminary Dm322 consistent with world average

e oscillation search: Number of events observed in agreement with expected background + standard oscillation Sterile oscillation constraints from ne and nt studies Prospects: re-analysis of the data with looser selection and multivariate analysis: more signal and background but significant statistical gain => estimation of oscillation parameters and couplings with the tau appearance Exploiting the unique feature of being able to identify all three neutrino flavours: 21 The end n event with 3 vertices Rates after topological selection (a first short decay in two prongs and the a long decay in one prong) 23 First nt candidate (event 9234119599, taken on 22/08/2009) In 2010 OPERA has published the first candidate based on the

analysis of 35% of 2008/2009. OPERA Phys. Lett. B 691 (2010) 138-145 VARIABLE Measured Selection criteria Kink (mrad) 41 2 >20 Decay length (mm) 1335 35 Within 2 plates P daughter (GeV/c) 12 +6-3 >2 PT daughter (MeV/c)

470 +230-120 >300 (g attached) Missing PT (MeV/c) 570 +320-170 <1000 (deg) 173 2 >90 24 Second nt candidate (event 11113019758, taken on 23/04/2011) OPERA Interaction Vertex in lead plate 1 nuclear fragment t h h h nt - + -

- Primary Track = (167.8 1.1) Flight length 1.54 mm m Decay point d3 In Plastic Base No nuclear fragment degrees Kink angle (rad) d2 d1 Secondary Interaction In Emulsion 4 nuclear fragments JHEP 11 (2013) 036 25 Third nt candidate (event 12123032048, taken on 2/05/2012) OPERA

t- m- nt VARIABLE VALUE Kink angle (mrad) 245 5 decay length (m) 376 10 P (GeV/c) 2.80.2 Pt (MeV/c) 69050 (degrees) 154.5 1.5 MC candidate Phys. Rev. D89 (2014) 051102 MC

candidate excluded region 26 Fourth nt candidate (event , taken on ) OPERA t-OPERA m- n t- h- nt t VARIABLE AVERAGE Kink angle (mrad) 245 5 decay length (m) 376 10 P (GeV/c) 2.80.2 Pt (MeV/c) 69050 (degrees)

154.5 1.5 PTEP (2014) 101C01 27 analysis: kinematical selection 28 oscillation analysis results: Dm232 = 3.3 x 10-3 eV with a 90% confidence interval [2.0, 5.0] x 10-3 eV2 (assuming full mixing) using profile likelihood, FeldmanCousins, Bayesian statistics, the difference among the methods negligible Probability to be explained by background Two statistical methods: - Fisher combination of single channel p-values - Profile likelihood ratio 29 Bacground sources: 41

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