Скачать презентацию Recent results on the observation of — oscillation Скачать презентацию Recent results on the observation of — oscillation

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Recent results on the observation of -> oscillation in the OPERA experiment Belgium ULB Recent results on the observation of -> oscillation in the OPERA experiment Belgium ULB Brussels Croatia IRB Zagreb France LAPP Annecy IPHC Strasbourg Germany Hamburg Israel Technion Haifa Italy Bari Bologna LNF Frascati L’Aquila LNGS Naples Padova Rome Salerno Japan Aichi edu. Kobe Nagoya Toho Utsunomiya Korea Jinju Russia INR RAS Moscow LPI RAS Moscow ITEP Moscow SINP MSU Moscow JINR Dubna Switzerland Bern ETH Zurich Turkey METU Ankara Nakatsuka. Yuji Nagoya University On behalf of OPERA collaboration ICISE Qui Nhon 2013 Aug 14 Rencontres du Vietnam Windows on the Universe 1

Aim and Principle Aim : Observation of neutrino oscillations in appearance mode through the Aim and Principle Aim : Observation of neutrino oscillations in appearance mode through the channel. Principle of OPERA Experiment : decay “kink” oscillation ~1 mm -, h-, e- plus 3 -prong decay modes Direct detection of > oscillation 2

Covers the region indicated by Super-K, K 2 K & MINOS CNGS Beam 732 Covers the region indicated by Super-K, K 2 K & MINOS CNGS Beam 732 km LNGS < E > ( Ge. V ) ( e + e) /   / prompt 17 0. 89, 0. 06 % 2. 1 % Negligible sin 22θ 23 = 1. 0,  Δm 232 = (2. 43± 0. 13)× 10 -3 e. V 2 [ Phys. Rev. Lett. 101: 131802, 2008. ] 3

The OPERA detector Underground@Gran. Sasso, ~1400 m Target Super-Module Muon Spectrometer Target Mass ~1. The OPERA detector [email protected] Sasso, ~1400 m Target Super-Module Muon Spectrometer Target Mass ~1. 2 kton 4

ECC selection Typical NC-like event 20 m 7. 5 cm 12. 5 cm Changeable ECC selection Typical NC-like event 20 m 7. 5 cm 12. 5 cm Changeable Sheet (CS) Interface emulsion films for ECC selection and track connection. 8. 3 kg 10 cm Neutrino Beam (vertical to films) Pb 1 mm Emulsion Cloud Chamber (ECC) Stack of 57 emulsion films, 56 lead plates (10 X 0). ~150, 000 ECC installed in the OPERA detector 5

Event location in ECC Follow back in the ECC tracks found in CS until Event location in ECC Follow back in the ECC tracks found in CS until they disappear: vertex plate ECC CS TT hit Large area Lead emulsion Lead emulsion Vertex plate Lead emulsion ~100 x 100 m 2 emulsion Point scan neutrino ~100 cm 2 TT hit 6 6 14

OPERA Film 44 um emulsion 210 um plastic base 200 nm   Ag. Br Crystal OPERA Film 44 um emulsion 210 um plastic base 200 nm   Ag. Br Crystal ~30 developed silver grains / 100 m M. I. P. track M. I. P. 10 Ge. V πFog 100 m m 20μm 125 mm A compton track 7

Japanese Scanning System (S-UTS) European Scanning System (ESS) Scanning speed/system: 75 cm 2/h Scanning Japanese Scanning System (S-UTS) European Scanning System (ESS) Scanning speed/system: 75 cm 2/h Scanning speed/system: 20 cm 2/h *High speed CCD camera (3 k. Hz) *Piezo-controlled objective lens *FPGA Hard-coded algorithms Event reconstruction *Customized commercial Optics and mechanics *Asynchronous DAQ software All track data ~ 1 cm x 1 cm Required plate-plate connection Tracks converge to vertex point 8

 CC detection Impact Parameter distribution Short flight decay events (MC) (Mean 104. 3 CC detection Impact Parameter distribution Short flight decay events (MC) (Mean 104. 3 m) NC+CC events (MC) NC+CC events (Data) Decay point IP Primary vertex 1 mm Pb Short : Long ~ 2: 8 Without muon Long flight decay 10 m ↔  (c = 87 m) decay mode 17. 8 % 15. 2 % Primary vertex 49. 5 %  → h- h- h+ IP 17. 4 %  → h. Trident  → e  → μ- Kink Decay point 1 mm Pb 9

 candidate events 1 st candidate -> 1 h, May 2010 ( ->r , candidate events 1 st candidate -> 1 h, May 2010 ( ->r , r-> 0 , 0 ->2 ) 2 nd candidate -> 3 h, June 2012 10

The 3 rd candidate event : -> decay mode μm 11 11 The 3 rd candidate event : -> decay mode μm 11 11

Event Display 2. 8 Ge. V muon 12 Event Display 2. 8 Ge. V muon 12

Event analysis beam transverse plane p pri. h ph total f=154. 5° Kink Angle Event analysis beam transverse plane p pri. h ph total f=154. 5° Kink Angle (mrad) 245± 5 Decay Length ( m) 376± 10 P (Gev/c) 2. 8± 0. 2 Decay Pt (Mev/c) 690± 50 Phi Angle (degrees) 154. 5± 1. 5 13

τ→μ MC τ→μ candidate excluded region Passed all cuts of -> decay criteria 14 τ→μ MC τ→μ candidate excluded region Passed all cuts of -> decay criteria 14

Muon sign 1. 55 T Target tracker hits Spectrometer 4 hits curvature radius ~ Muon sign 1. 55 T Target tracker hits Spectrometer 4 hits curvature radius ~ 85 cm muon charge is negative 5. 6 s > : identification of oscillated interaction (≠ ) 15

 - e h BG 1 : Charm Decay n Charm BG The same - e h BG 1 : Charm Decay n Charm BG The same topology charm + - decay miss id charm decay the decay muon charge is plus. 16

BG 2 : Muon Large Angle Scattering Prob muon kink point Pb   quark Film BG 2 : Muon Large Angle Scattering Prob muon kink point Pb   quark Film Kink Angle (mrad) 245± 5 Decay Pt (Mev/c) 690± 50 Tranverse momentum PDF Scattering probability is proportional to the amount of material. Pb : 10 -6 film (emulsion + plastic base) : 10 -8 - 10 -7 104 690 Me. V/c at base Upper limit : Proposal Value 10 -5 (S. A. Akimenko et at al, NIM A 423 1986 518) 0 500 1000 PT (Me. V/c) 17

Summary of -> search status n n Three candidates have been found, 1 st Summary of -> search status n n Three candidates have been found, 1 st : - > h, 2 nd : -> 3 h, 3 rd : -> . The 3 rd event is pure -> channel with low background and tagged as by its muon sign. Probability explained by only background ~ 7. 29 x 10 -4 The singnificance value : counting method : 3. 2 s of non-null observation, likelihood approach : 3. 5 s scattering Signal Background Charm had int h 0. 66 0. 045 0. 029 0. 016 3 h 0. 51 0. 090 0. 087 0. 003 0. 56 0. 026 0. 0084 e 0. 49 0. 065 total 2. 22 0. 226 0. 19 0. 018 0. 019 18

Conclusions and Prospects n OPERA ran on the CNGS beam successfully 2008 -2012, 17. Conclusions and Prospects n OPERA ran on the CNGS beam successfully 2008 -2012, 17. 97 x 1019 POT, ~80 % of proposal value of CNGS beam n Analysis stasus : completed 2008, 2009 events. 2010 - 2012 events are on going, main part (1 st ECC) will finish in 2013. n n Three candidates have been found, counting method 3. 2 s of non-null observation, likelihood approach : 3. 5 s Searches are on going for more interesting events, within reach 4 s observation. 19

backup 20 backup 20

Charm Decay Event Candidates 21 Charm Decay Event Candidates 21

22 22

Beam exposure and analysis status (13 Jul 28) Run 2008 → 2012 ‘ 08 Beam exposure and analysis status (13 Jul 28) Run 2008 → 2012 ‘ 08 ‘ 09 ‘ 10 ‘ 11 ‘ 12 p. o. t. event CS scanned 14802 CS found 10776 ECC scanned 9981 DS 5036 date Beam: 5 years (965 days) 17. 97× 1019 p. o. t. Overall 80% of the proposal value (22. 5× 1019 p. o. t. ) date Completed: 2008, 2009 2010 -12 on going with optimised strategy (ALL NC-like events and CC-like events with momentum < 15 Ge. V/c) 23

The first “appearance” candidate (2010) Candidate interaction and decay from oscillation 24 The first “appearance” candidate (2010) Candidate interaction and decay from oscillation 24

First tau neutrino candidate event Muonless event 9234119599, taken on 22 nd August 2009 First tau neutrino candidate event Muonless event 9234119599, taken on 22 nd August 2009 (as seen by the electronic detectors) 25 G. De Lellis - Fermilab - 4 June 2010

Event reconstruction in the brick τ −→ − ν τ ρ ρ −→ 0 Event reconstruction in the brick τ −→ − ν τ ρ ρ −→ 0 π π π 0 → γ γ 26

PL 17 PL 18 PL 19 PL 20 PL 21 5 7 1 3 PL 17 PL 18 PL 19 PL 20 PL 21 5 7 1 3 Primary vertex 1 kink point 4 8 careful visual inspection of the films behind/in front of the secondary vertex: 2 no “black” or “evaporation” tracks. Support topological hypothesis of a particle decay 1 mm lead 6 27

Kinematical variables • Kinematical variables are computed by averaging the two independent sets of Kinematical variables • Kinematical variables are computed by averaging the two independent sets of measurements • 1 and 2 both attached to 2 ry vertex VARIABLE AVERAGE kink (mrad) 41 ± 2 decay length ( m) 1335 ± 35 P daughter (Ge. V/c) 12 +6 -3 Pt (Me. V/c) 470 +240 -120 missing Pt (Me. V/c) 570 +320 -170 ϕ (deg) 173 ± 2 28

Second neutrino tau candidate event taken on 23 rd April 2011 as seen by Second neutrino tau candidate event taken on 23 rd April 2011 as seen by the electronic detector event display 29

animation Second  Candidate Event 2000 m 30 animation Second  Candidate Event 2000 m 30

Schematics of the event Φ Beam View Φ=167 o Secondary Interaction In Emulsion 31 Schematics of the event Φ Beam View Φ=167 o Secondary Interaction In Emulsion 31 With four Nuclear fragments

Zoom of the primary interaction and decay region Decay point In Plastic Base No Zoom of the primary interaction and decay region Decay point In Plastic Base No Nuclear fragment Flight length 1. 54 mm 32

Momentum measurement and particle identification of event tracks Track# Momentum (1σ interval) [ Ge. Momentum measurement and particle identification of event tracks Track# Momentum (1σ interval) [ Ge. V/c] Particle ID Method / Comments Primary 2. 8 (2. 1 -3. 5) Hadron n Momentum-Range Consistency Check Stops after 2 brick walls. Incompatible with muon ( 26 44 brick walls) d 1 6. 6  (5. 2 - 8. 6) Hadron n Momentum-Range Consistency Check d 2 1. 3  (1. 1 -1. 5) Hadron n Momentum-Range Consistency Check d 3 2. 0 (1. 4 - 2. 9) Hadron Interaction in the Brick @ 1. 3 cm downstream Independent momentum measurements carried out in two labs 33

Kinematics of the second Candidate Event Cut Value φ (Tau - Hadron) [degree] >90 Kinematics of the second Candidate Event Cut Value φ (Tau - Hadron) [degree] >90 167. 8± 1. 1 average kink angle [mrad] < 500 87. 4± 1. 5 Total momentum at 2 ry vtx [Ge. V/c] > 3. 0 8. 4± 1. 7 Min Invariant mass [Ge. V/c 2] 0. 5 < < 2. 0 0. 96± 0. 13 Invariant mass [Ge. V/c 2] 0. 5 < < 2. 0 0. 80± 0. 12 Transverse Momentum at 1 ry vtx [Ge. V/c] < 1. 0 0. 31± 0. 11 34

Kinematics of the second candidate event candidate cut Satisfying the criteria for ντ 3 Kinematics of the second candidate event candidate cut Satisfying the criteria for ντ 3 hadron decay 35

Analysis of the interface films μ track Sign of electromagnetic shower 36 Analysis of the interface films μ track Sign of electromagnetic shower 36

Third tau neutrino event τ μ μm 37 Third tau neutrino event τ μ μm 37

Event tracks’ features TRACK NUMBER PID MEASUREMENT 1 MEASUREMENT 2 ΘX ΘY P (Ge. Event tracks’ features TRACK NUMBER PID MEASUREMENT 1 MEASUREMENT 2 ΘX ΘY P (Ge. V/c) ΘX ΘY P (Ge. V/c) 1 DAUGHTER MUON -0. 217 -0. 069 3. 1 [2. 6, 4. 0]MCS -0. 223 -0. 069 2. 8± 0. 2 Range (TT+RPC) 2 HADRON Range 0. 203 -0. 125 0. 85 [0. 70, 1. 10] 0. 205 -0. 115 0. 96 [0. 76, 1. 22] 3 PHOTON 0. 024 -0. 155 2. 64 [1. 9, 4. 3] 0. 029 -0. 160 3. 24 [2. 52, 4. 55] 4 PARENT TAU -0. 040 0. 098 -0. 035 0. 096 γ attachment 38

Muon charge and momentum reconstruction Muon momentum by range in the electronic detector: 2. Muon charge and momentum reconstruction Muon momentum by range in the electronic detector: 2. 8± 0. 2 Ge. V/c MCS in the brick consistent 3. 1 [2. 6, 4. 0] Ge. V/c ϑ (mrad) Bending by the magnetic field Cells 39

Track follow down to assess the nature of track 2 Track 2 interacting in Track follow down to assess the nature of track 2 Track 2 interacting in the downstream brick without visible charged particles track value Momentum/range inconsistent with μ hypothesis 0. 9 Ge. V/4 cm Lead L = track length Rlead = µ range ρaverage = average density ρlead = lead density p = momentum in emulsion Hadrons and muon stopping in the brick cut value 40 D variable

THE MAGNETIC SPECTROMETERS • 1. 55 T magnetic field bending particles in the horizontal THE MAGNETIC SPECTROMETERS • 1. 55 T magnetic field bending particles in the horizontal plane • 24 slabs of magnetized iron interleaved with 24 RPC planes • 6 drift tube stations for precision measurement of the angular deflection • momentum resolution: 20% below 30 Ge. V 41

 µ→ e analysis 4. 1 Ge. V electron ≈ 30 events found in µ→ e analysis 4. 1 Ge. V electron ≈ 30 events found in the analyzed sample 42

Electron neutrino search in 2008 and 2009 runs: one of the νe events with Electron neutrino search in 2008 and 2009 runs: one of the νe events with a π0 as seen in the brick Interface films 19 candidates found in a sample of 505 neutrino interactions without muon 43

 Background from µNC ( 0→ ) Gamma-ray 1 micron A close-up of an Background from µNC ( 0→ ) Gamma-ray 1 micron A close-up of an electron pair BG: 0. 17 events (less than 1%) 44

Energy distribution of the 19 νe candidates Observation compatible with background-only hypothesis: 19. 8± Energy distribution of the 19 νe candidates Observation compatible with background-only hypothesis: 19. 8± 2. 8 (syst) events 3 flavour analysis Energy cut to increase the S/N 4 observed events 4. 6 expected ⇒ sin 2(2θ 13)<0. 44 at 90% C. L. 45

Search for non-standard oscillations at large Δm 2 values: exclusion plot in the sin Search for non-standard oscillations at large Δm 2 values: exclusion plot in the sin 2(2θnew) - Δm 2 new plane ar. Xiv: 1303. 3953 Submitted to JHEP Caveat: experiments with different L/E values 46

Background estimation (hadron) Error bars : Experimen Histogram : Simulated We confirmed MC simulation Background estimation (hadron) Error bars : Experimen Histogram : Simulated We confirmed MC simulation estimation of hadron backgrounds by using the data analysis of ECC bricks exposed to 2 Ge. V/c , 4 Ge. V/c and 10 Ge. V/c pion beams and reduced systematic uncertainty. Secondary track emission: 30% 2 Ge. V/c 4 Ge. V/c nuclear fragments: 10% 2 Ge. V/c 10 Ge. V/c Multiplicity 0 Multiplicity 5 0 8 They argee well Kink angle (1 -prong) 0. 6 0 MC: b < 0. 7 0 15 0 0. 6 0 Forward 0. 6 180° New technique for background reduction 15 0 15 Well reproduced by MC Emission angle(cos q) Backward 0 10 Ge. V/c 4 Ge. V/c Backward Forward 0° 180° 0° Nuclear fragment associated probability 100% ・ data - MC nuclear fragments in emulsion 0% 2 4 8 10 Ge. V/c 47 47 Hadronic background was reduced by “ 40%” by requiring no association of large angle nuclear fragments.

Track recognition method • Take 16 tomographic images by microscope optics. • Shift images Track recognition method • Take 16 tomographic images by microscope optics. • Shift images to aim at specific angle tracks. • Sum up 16 images to examine coincidence. • Find signal of tracks. • Repeat for all angles in space, >2000 times Invented by K. Niwa in 1974 48