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OPERA

VIEWS: 13 PAGES: 52

  • pg 1
									        OPERA experiment :
Preliminary results from the 2008 run

               Guillaume Lutter

             LHEP, University of Bern
         on behalf of OPERA collaboration


            LLWI 09 - February 17th 2009
                                Motivation
•   Super-Kamiokande observed νμ disappearance in atmospheric neutrinos flux
     atmospheric neutrinos oscillations hypothesis
•   No direct detection of neutrino oscillation in appearance mode
      Purpose of the OPERA experiment : Observe ντ appearance in a pure νμ beam




                                                                                   1
                                Motivation
•   Super-Kamiokande observed νμ disappearance in atmospheric neutrinos flux
     atmospheric neutrinos oscillations hypothesis
•   No direct detection of neutrino oscillation in appearance mode
      Purpose of the OPERA experiment : Observe ντ appearance in a pure νμ beam

                    P(t) ~ sin2223cos413sin2(m223L/4E)
                                with Δm232 = (2.43±0.13)×10-3 eV2   sin22θ23 ~1   cos 13~1




                                                                                          1
                                         Motivation
•   Super-Kamiokande observed νμ disappearance in atmospheric neutrinos flux
     atmospheric neutrinos oscillations hypothesis
•   No direct detection of neutrino oscillation in appearance mode
      Purpose of the OPERA experiment : Observe ντ appearance in a pure νμ beam

                       P(t) ~ sin2223cos413sin2(m223L/4E)
                                         with Δm232 = (2.43±0.13)×10-3 eV2   sin22θ23 ~1   cos 13~1
Requirements:
• Long baseline
• High beam intensity (σν ~ 10-40 cm2)
• Low cosmic background




                                                                                                   1
                                         Motivation
•   Super-Kamiokande observed νμ disappearance in atmospheric neutrinos flux
     atmospheric neutrinos oscillations hypothesis
•   No direct detection of neutrino oscillation in appearance mode
      Purpose of the OPERA experiment : Observe ντ appearance in a pure νμ beam

                       P(t) ~ sin2223cos413sin2(m223L/4E)
                                         with Δm232 = (2.43±0.13)×10-3 eV2   sin22θ23 ~1   cos 13~1
Requirements:
• Long baseline
• High beam intensity (σν ~ 10-40 cm2)
• Low cosmic background
• Detect short lived τ’s




                                                                                                   1
                                         Motivation
•   Super-Kamiokande observed νμ disappearance in atmospheric neutrinos flux
     atmospheric neutrinos oscillations hypothesis
•   No direct detection of neutrino oscillation in appearance mode
      Purpose of the OPERA experiment : Observe ντ appearance in a pure νμ beam

                       P(t) ~ sin2223cos413sin2(m223L/4E)
                                         with Δm232 = (2.43±0.13)×10-3 eV2   sin22θ23 ~1   cos 13~1
Requirements:
• Long baseline
• High beam intensity (σν ~ 10-40 cm2)
• Low cosmic background
• Detect short lived τ’s


Detector needs :
• High granularity
(signal selection & background reduction)
• Large mass (low cross section)


                                                                                                   1
                                         Motivation
•   Super-Kamiokande observed νμ disappearance in atmospheric neutrinos flux
     atmospheric neutrinos oscillations hypothesis
•   No direct detection of neutrino oscillation in appearance mode
      Purpose of the OPERA experiment : Observe ντ appearance in a pure νμ beam

                       P(t) ~ sin2223cos413sin2(m223L/4E)
                                         with Δm232 = (2.43±0.13)×10-3 eV2   sin22θ23 ~1   cos 13~1
Requirements:
• Long baseline
• High beam intensity (σν ~ 10-40 cm2)
• Low cosmic background
• Detect short lived τ’s


Detector needs :
• High granularity
(signal selection & background reduction)
• Large mass (low cross section)
     Nuclear emulsions
                                                                                                   1
                                         Motivation
•   Super-Kamiokande observed νμ disappearance in atmospheric neutrinos flux
     atmospheric neutrinos oscillations hypothesis
•   No direct detection of neutrino oscillation in appearance mode
      Purpose of the OPERA experiment : Observe ντ appearance in a pure νμ beam

                       P(t) ~ sin2223cos413sin2(m223L/4E)
                                         with Δm232 = (2.43±0.13)×10-3 eV2   sin22θ23 ~1   cos 13~1
Requirements:
• Long baseline
• High beam intensity (σν ~ 10-40 cm2)
• Low cosmic background
• Detect short lived τ’s


Detector needs :
• High granularity
(signal selection & background reduction)
• Large mass (low cross section)
     Nuclear emulsions
• Installed in underground laboratory                                                              1
                            The OPERA collaboration
                                     Brussels
                        Bern,
   Annecy, Lyon,        Zurich                                                          Dubna, Moscow
                                                Hamburg, Münster,   Zagreb   Sofia   (INR,LPI,ITEP,SINP
    Strasbourg
                                                    Rostock                             MSU) Obninsk




                                                                                                   Aichi, Toho
   L’Aquila, Bari,
                                                                                                  Kobe, Nagoya
  Bologna, Frascati,
                                                                                                   Utsunomiya
LNGS, Napoli, Padova,
    Roma, Salerno




   Technion Haifa
                                                                                                  Gyeongsang




                    METU Ankara   35 INSTITUTIONS, ~200 PHYSICISTS

                                                                                                          2
The Oscillation Project with Emulsion tRacking Apparatus experiment
                          Observe ντ appearance in a pure νμ beam
• CNGS (CERN to Gran Sasso) beam
                               νμ beam tuned for the τ appearance at LNGS (730 km away from CERN)


                                                     Mean νμ energy : 17 GeV

                                           Requested to deliver : 22.5 x 1019 pot (5 years)

                                       The OPERA detector is installed in LNGS (Italy) which is
                                       the largest underground laboratory in the world




                                                                                                  3
The Oscillation Project with Emulsion tRacking Apparatus experiment
                            Observe ντ appearance in a pure νμ beam
• CNGS (CERN to Gran Sasso) beam
                                 νμ beam tuned for the τ appearance at LNGS (730 km away from CERN)


                                                          Mean νμ energy : 17 GeV

                                               Requested to deliver : 22.5 x 1019 pot (5 years)

                                            The OPERA detector is installed in LNGS (Italy) which is
                                            the largest underground laboratory in the world

• The OPERA target
    Basic component: OPERA Brick = 57 nuclear emulsion films interleaved by 1 mm thick lead plates
                                                                Emulsion

                                                                                 Film : 2 emulsion layers
                                                                                      (44 m thick)
                                                                                       poured on a
                               10.2 cm                                             205 m plastic base
                                         12.5 cm                                 (δx~1 μm δθ~1 mrad)
                                                                                                       3
    8.3 kg         7.5 cm
                                                                  Plastic base
The Oscillation Project with Emulsion tRacking Apparatus experiment
                            Observe ντ appearance in a pure νμ beam
• CNGS (CERN to Gran Sasso) beam
                                 νμ beam tuned for the τ appearance at LNGS (730 km away from CERN)


                                                          Mean νμ energy : 17 GeV

                                               Requested to deliver : 22.5 x 1019 pot (5 years)

                                            The OPERA detector is installed in LNGS (Italy) which is
                                            the largest underground laboratory in the world

• The OPERA target
    Basic component: OPERA Brick = 57 nuclear emulsion films interleaved by 1 mm thick lead plates
                                                                Emulsion

                                                                                 Film : 2 emulsion layers
                    The OPERA target is composed of 150,036 bricks m thick)
                                                                (44
                                   Total target mass : 1.25 kt                        poured on a
                               10.2 cm                                            205 m plastic base
                                         12.5 cm                                 (δx~1 μm δθ~1 mrad)
                                                                                                       3
    8.3 kg         7.5 cm
                                                                  Plastic base
The Oscillation Project with Emulsion tRacking Apparatus experiment
• The OPERA detector




                                                            10m




                                                10m
                       20m




                                                                  4
The Oscillation Project with Emulsion tRacking Apparatus experiment
• The OPERA detector




                                                                4
 The Oscillation Project with Emulsion tRacking Apparatus experiment
 • The OPERA detector




CNGS Beam




                                                                 4
 The Oscillation Project with Emulsion tRacking Apparatus experiment
 • The OPERA detector

    Super Module 1                 Super Module 2




CNGS Beam




                                                                 4
 The Oscillation Project with Emulsion tRacking Apparatus experiment
 • The OPERA detector

    Super Module 1                 Super Module 2




                                                          Scintillator strip
CNGS Beam
                                                Brick

                                                            Target

                                               ● Target : 75,018 bricks, 29 walls
                                               ● Scintillator strips for :
                                                     • Brick selection
                                                     • Calorimetry
                                                                                    4
 The Oscillation Project with Emulsion tRacking Apparatus experiment
 • The OPERA detector

    Super Module 1                                Super Module 2




CNGS Beam



                                                                           Target

                                                              ● Target : 75,018 bricks, 29 walls
                                                              ● Scintillator strips for :
                                                                    • Brick selection
                 Muon spectrometer                                  • Calorimetry
         for momentum and charge identification
                of penetrating particles                                                           4
                    Event Reconstruction
Electronic data (Target Tracker & Muon spectrometer)




                                                       5
                    Event Reconstruction
Electronic data (Target Tracker & Muon spectrometer)




                                        Track identified as a muon (P=3.394 GeV/c)   5
                    Event Reconstruction
Electronic data (Target Tracker & Muon spectrometer)


                                                               ~ 1.5 m




                                        Track identified as a muon (P=3.394 GeV/c)   5
                       Event Reconstruction
  Electronic data (Target Tracker & Muon spectrometer)


                                                                   ~ 1.5 m




A brick has been selected by the BrickFinder algorithm




                                            Track identified as a muon (P=3.394 GeV/c)   5
                       Event Reconstruction
  Electronic data (Target Tracker & Muon spectrometer)


                                                                   ~ 1.5 m




A brick has been selected by the BrickFinder algorithm
 Brick is extracted from the detector




                                            Track identified as a muon (P=3.394 GeV/c)   5
                       Event Reconstruction
  Electronic data (Target Tracker & Muon spectrometer)


                                                                   ~ 1.5 m




A brick has been selected by the BrickFinder algorithm
 Brick is extracted from the detector
 Brick is developed in LNGS




                                            Track identified as a muon (P=3.394 GeV/c)   5
                       Event Reconstruction
  Electronic data (Target Tracker & Muon spectrometer)


                                                                   ~ 1.5 m




A brick has been selected by the BrickFinder algorithm
 Brick is extracted from the detector
 Brick is developed in LNGS
 Brick is sent to a scanning laboratory




                                            Track identified as a muon (P=3.394 GeV/c)   5
                      Emulsions Analysis
                                              Bern emulsion scanning lab.
Emulsions are scanned in a fully
automatic way by using microscopes.
About 40 microscopes are operational
in the various OPERA scanning
laboratories.


                 300 m
Nuclear fragment


                           Nuclear fragment


                    Muon track


                          Nuclear fragment



                                                                       6
                             Emulsions Analysis
                                                        Bern emulsion scanning lab.
       Emulsions are scanned in a fully
       automatic way by using microscopes.
       About 40 microscopes are operational
       in the various OPERA scanning
       laboratories.


                        300 m
       Nuclear fragment


        Real  CC interaction
                             Nuclear      fragment
                                                 h   Predictions from electronic
                                                     detectors are followed back
                           Muon track                inside the brick until tracks
                                                     stop. Then a full scanning
2 mm




                                                     around neutrino interaction
                                 Nuclear fragment
                                             muon    vertex is performed and the
                                                     event topology and kinematics
                                                     reconstructed.
                             2 cm                                                6
                   Charm candidate Event (real data)
          pl50 pl51 pl52   pl53   pl54 pl 55 pl 56 pl57
side




   face                                                    Clear kink topology
                                                           Two EM showers pointing to the vertex

                                                          Flight length       3247.2 μm
                                                          kink               0.204 rad
                                                          Pdaughter           3.9 (+1.7 -0.9) GeV
                                                          PT                  796 MeV

                                                          4x10-4 % probability for a hadron re-interaction to
                                                          have a PT > 600 MeV                              7
        2nd Charm candidate Event (real data)


Primary interaction
                      Decay in 3 prongs




                                          Three charged prongs decay

                                          Flight length : ~1150 μm
                                          Angle (muon – 3 prongs decay) : ~150°

                                          Kaon decay probability : 10-4 %
                                          Hadron re-interaction probability : 1x10-5 %

                                                                                   8
                      muon
     3rd Charm candidate Event (real data)
top view                              side view



                             muon

                                                  muon




  Two charged prongs decay

  Flight length    less than 202 μm
  PT               minimum 2.7 GeV

                                                     9
         Analysis and event reconstruction capabilities

Muons produced in charged current neutrino interactions inside the OPERA target:




                                                 Mean vertical angle : (3.5 ± 0.2)°
                                                 [3.3° expected from the geodesy]
                                                                                 10
               OPERA experiment Status
• May 2006: electronic detector commissioning
• October 2007: pilot physics run (~40% target) 0.082x1019 pot
first 38 neutrino events in the lead/emulsion target
• June 2008: OPERA detector filled and fully commissioned (~150,000 bricks)
• June – November 2008 : First OPERA production run

                                                2008 Run
 1.8x1019 pot and ~1700 neutrino events in the target
  Expected number of IDENTIFIED charmed events in detector: 26
 Expected number of IDENTIFIED tau events : 0.6



Beginning of January 2009
•   Number of developed brick : 754
•   Event located : 446
•   In progress : 308
•   Brick finding efficiency : 75.9 % (MC predicts 72%)
•   Vertex finding efficiency :       84-94 % (Charged current event)         (93% from MC)
                                      71-92 % (Neutral current event)         (81% from MC)

                                                                                              11
                  Conclusion & Perspective
•   With a beam intensity of 22.5 x 1019 pot, a target mass of 1300 tons and Δm223=2.5x10-3 eV2 :
      ~25000        neutrino interactions
      ~120          t interactions
                                                       in 5 years
      ~10           t identified
      <1            background events
•   The OPERA experiment has started full data taking in the CNGS beam:
          2008 run: ~1.8x1019 pot, ~1700 interactions in the bricks
          ~0.6 identified τ events expected
    Event location in progress : 446 events (beginning of january)
•   Detector and ancillary facilities performed extremely well
•   Detection efficiencies and backgrounds are being computed with real data
•   Interesting events have already been analyzed (Charm, Nu-e)
•   Forecast for 2009:
          173 days of running: ~3.5x1019 pot
          Sufficient integrated statistics for candidate events (~2 tau events)
          Precise evaluation of efficiencies, backgrounds and sensitivity
                                                                                                12
FIN


      Event 234533895, Brick 1015221, 10/10/2008, νμCC
Backup slides
CNGS
CNGS neutrino flux at LNGS
CNGS beam (CERN Neutrino to Gran Sasso)
                                           4.5 1019 p.o.t. /year
  Flux at Gran Sasso (given by Fluka)
                    P(->t)*s(t CC)
                                           Number of expected events at
                    m223 = 2.5 10-3 eV²     Gran Sasso (0-100 GeV):
                                               (before reconstruction and
                                                 detection efficiencies)
           flux                               N  CC= 3000/yr/kton
                                                 N e CC= 20 /yr/kton
                                                 N t CC= 14 /yr/kton
Tau & OPERA Performance
 t appearance signature
.Detection of t CC interaction and direct observation of decay topology
.High background rejection

           t     decay
               kink
                                     t-      - t              (17.4%)
                    t                t-      e-  t  e           (17.8%)
                                     t-      h- t n(po)           (49.5%)
      t                             t-      p+ p- p- t n(po)     (14.5%)
                          OPERA ντ observation probability

                                    Assume 22.5x1019 pot, ~10 signal events, < 1 BG
Discovery probability %




                                        3   σ   sensitivity


                                    4   σ   sensitivity




                                                 SK 90% CL
                                                (L/E analysis)   Last MINOS
                                                                 measurement
                                            • 5 years CNGS data taking
  OPERA τ    search sensitivity              ( 4.5 1019 pot/year )
                                            • 1.35 ktons target mass




t- decay       Signal ÷ m2 (Full mixing)
                                                      Background
channels
            2.5 x 10-3 (eV2)   3.0 x 10-3 (eV2)

 t-  µ-          2.9                4.2                  0.17

 t -  e-         3.5                5.0                  0.17

 t-  h-          3.1                4.4                  0.24

t-  3h           0.9                1.3                  0.17

  ALL            10.4               15.0                  0.76
                           τ search : Backgrounds
                                                                 -
                       Primary lepton                    
,e          ,e-     not identified
                                                                         Coulombian large angle
                  +       Charm production in CC,                       scattering of muons in
        D+        e+       common to the 3 channels                      Lead : Bck. to t  
  Same decay      h+
  topology as t            Good muon identification
                           is fundamental
                                                                              Hadronic interactions
                                                                            in Pb: Bck. to t  h
                                                          
                                                                              or to t  
Expected number of                                                   h        (if hadron mis-
                                                                          h   identified as muon)
background events
after 5 years running
with nominal beam:

                                 τe           τμ       τh          τ3h Total
   Charm background                     .173      .008        .134            .181        .496
   Large angle μ scattering                       .096                                    .096
   Hadronic background                            .077        .095               .        .172
   Total per channel                    .173      .181        .229            .181        .764
                      e
               oscillation search




2.5x10-3 eV2

                                      m232 = 2.5 x 10-3 eV2   23 = 45°

                                      nominal CNGS beam        5 years




                                    90% C.L. limits on sin2(213) and 13 :

                                         sin2(213)<0.06 13 < 7.1º
OPERA
                  OPERA detector at LNGS
(National Laboratory of Gran Sasso, Italy, 120 kms from Rome)

rock thickness 1400m (3800 m.w.e.)
cosmic muon flux: 1/m2/h

                     Hall B
                                               ICARUS (CNGS2)
                                                 BOREXINO

                                      Hall C

                                                OPERA (CNGS1)




LNGS-INFN
  The Oscillation Project with Emulsion tRacking Apparatus experiment


          Super Module 1                                                               SM2



                                             δx=1 cm δθ=10-20 mrad




                                                                           Target and Target Tracker (6.7m)2
Veto plane (RPC)                                                       ● Target : 77500 bricks, 29 walls
  High precision tracker   Instrumented dipole magnet                  ● Target tracker : 31 XY doublets of 256
  ● 64-fold layers of      ● 1.53 T                                    scintillator strips + WLS fibres + multi-anodes
   drift tubes             ● 22 XY planes of Resistive Plane Chamber   PMT for
                           in both arms                                       • Brick selection
                                                                              • Calorimetry
                   Muon spectrometer (8×10 m2)
Divers
 Event 183545620 located in Bern – first e candidate




                        EM shower
Neutrino vertex
                        E = 4.71.3 GeV
IP = ~3m




                                                        8 mm
                                          24 mm

								
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