1 NuFact’01 WG1 : Neutrino Oscillation Physics May 24-30, 2001 An appearance experiment to search for  -  oscillations in the CNGS beam CNGS1 O scillation P roject with E mulsion-t R acking A pparatus May 25, Nagoya University M. Komatsu

2 The experimental technique Emulsion Cloud Chamber (ECC) –Emulsions for tracking, passive material as target –Basic technique works charmed “X-particle” first observed in cosmic rays (1971) DONUT/FNAL beam-dump experiment:  events observed  m 2 = ( ) x10 -3 eV 2 ( SuperK)   M target ~ 2 kton of ECC –large detector  sensitivity, complexity –modular structure (“bricks”): basic performance is preserved Ongoing developments in the emulsion technique, required by the large vertex detector mass: –industrially produced emulsion films –automatic scanning microscopes with ultra high-speed Pb Emulsion layers  1 mm Experience with emulsions and/or  searches : E531, CHORUS, NOMAD and DONUT

3 ~ 10 m The detector at Gran Sasso (modular structure, configuration with three “supermodules”)  spectrometer Magnetised Iron Dipoles Drift tubes and RPCs target and  decay detector Each “supermodule” is a sequence of 24 “modules” consisting of - a “wall” of Pb/emulsion “bricks” - planes of orthogonal scintillator strips scintillator strips brick wall module brick (56 Pb/Em. “cells”) 8 cm (10X 0 ) supermodule

4 8 m Target Trackers Pb/Em. target Electronic detectors  select  interaction brick A “hybrid” experiment Emulsion scanning  vertex search Extract selected brick Pb/Em. brick 8 cm Pb 1 mm Basic “cell” Emulsion  decay search  spectrometer  e/  ID, kinematics   ID, charge and p  (DONUT)

5 Origami packed ECC brick for OPERA Origami packing = vacuum packing (1) Protection against light and humidity variations. (2) Keep the position between films and Pb plates. (3) Vacuum preserved over 10 years 10X 0 ( 56 emulsion films ) 8kg for each brick 12.5cm 235k bricks for 3 supermodules Similar packing was used for E531,CHORUS,etc. DONUT did not use this packing then we had trouble.

6 Structure: OPERA ECC = DONUT ECC Material : Lead  Iron Better performance for physics analysis   has been detected in the DONUT ECC    hadron Emulsion Cloud Chamber for  detection 1mm Fe plate Emulsion film

7 The First  detection in ECC Iron-Emulsion ECC target –50cm x 50cm x 7cm(47 Iron plate : 2.7X 0 ) –Topology, momentum and e-ID in ECC Beam –3.5x10 17 POT, Apr.-Sep. ‘97 –Approximately 1,100 three flavor neutrino interactions –785 events in target region. Data taking –337 events located and 289 decay search done. –We are waiting faster scanning system for high multiplicity at TT events. Tau and charm events –6 tau events –2 charged and 2 neutral charms

8 6th tau event in DONUT ECC

9 Momentum measurement in DONUT ECC Momentum measurement by multiple scattering Consistent result with momentum measured by spectrometer.

10 Developed in DONUT analysis –3D tracking in emulsion using fast automatic scanning system(UTS) –Reconstruct all tracks recorded in emulsion Application in CHORUS “Phase II” –1.5mm x 1.5mm x 6.3mm(8 plates) –Tau search(0  events) and charm physics –Offline event reconstruction and event selection Data taking –13,000 events/month (440 events/day) –Data taking finished for 107,590 events. NETSCAN in CHORUS Phase II We have started our phase II analysis with the aim of reaching our design sensitivity of P  = 10 -4

11 Nov. ‘99 CHORUS Phase II data taking

12 Netscan (Chorus phase II) 1.5 mm All track segments (6k hits) 8 plates overlapped 6.3 mm Yellow : Upstream Red : Downstream

mm Small impact parameter Netscan (Chorus phase II) Yellow : Upstream Red : Downstream  CC D 0

14 Charm search in CHORUS NETSCAN 108k Data sets are ready for analysis Offline charm selection –23,244 CC events done – ~900 events selected (~4%) – 568+  charms (manual confirm is going on) ~70% purity for charm ~15% hadronic re-interactions, electron pairs and other int. The other ~15% are junk. Preliminary charm detection efficiency –Selection require TT track reconstruction Reconstruction efficiency for hadron tracks are 47-64% –26,63,58 and 75% for 1,2,3 and 4 prong decays Lower efficiency for D + and  c + due to long and short life time. Preliminary

15 Emulsion readout system –‘94 : We decided to apply full automatic scanning for CHORUS analysis. Emulsion became “Tracking detector”. –‘96 : ECC for DONUT target Pure tracking device –‘98 : Establish “NETSCAN” Current readout system “UTS” make us possible to perform volume scanning. These changes were driven by faster emulsion readout system. OPERA needs x20 faster readout system The key technology for OPERA

16 S-UTS Scanning speed: 20cm 2 /h  20 faster than the current system (UTS) S-UTS ‘94 ‘96 ‘98 ‘01 NTS UTS S-UTS Will be realized by  Fast CCD camera (3 k frames/sec)  Continuous movement of the X-Y stage Z movement controlled by piezo actuator late summer 2001  first S-UTS

17 Emulsion Scanning Lab in Nagoya Upgraded for OPERA  CHORUS, DONUT,OPERA and R&D for next generation

18  Interactions with 1.8 kton target x 5 years ~ NC+CC ~ 240  CC for SuperK best fit : sin 2 2  = 1  m 2 = 3.2x10 -3 eV 2 The CNGS beam Shared SPS operation 200 days/year 4.5x10 19 pot / year Nominal beam  ( m -2 / pot) 7.45x10 -9  CC / pot / kton 5.44x ( GeV ) 17 ( e + e ) /  0.85 %  /  2.0 %  prompt negligible

19 Analysis steps Brick finding Trigger Vertex location Decay search “long” or “short” decays  decay mode Kinematics   events Classify as  / e yes no Electronic detectors Emulsions Electronic detectors  e at 1ry vtx ? CHORUS DONUT

20 Summary of  detection efficiencies (in % and including BR) * weighted sum of DIS and QE events Channels considered in the Progress Report:   e (DIS+QE, long)     (DIS+QE, long)  Overall efficiency 

21 Expected background events (5 years data taking) Long decays Short decays

22  m 2 = 1.2x10 -3 eV 2 at full mixing sin 2 (2  ) = 6.0x10 -3 at large  m 2 (average 90 % CL upper limit for a large number of exp. ts in the absence of a signal) 5 years 3 years Sensitivity 5 years data taking

23 Full mixing 5 years with shared SPS operation (2.25x10 20 pot) Average target mass = 1.8 kton (accounting for mass reduction with time, due to brick removal for analysis) Expected events  events  decay  m 2 (10 -3 eV 2 ) b.g e  h Total  m 2 (eV 2 ) events expected in 5 years (log scale)

24 Summary and conclusions for OPERA Experience with E531, CHORUS, NOMAD and DONUT  appearance and  m 2 measurement at CNGS OPERA :  appearance and  m 2 measurement at CNGS Basic technique (ECC) works; preserved by modularity Basic technique (ECC) works; preserved by modularity Large detector  sensitivity, complexity Ongoing developments in the emulsion technique: – industrially produced emulsion films – automatic scanning microscopes with ultra high-speed The sensitivity covers the SuperK range; very low b.g. Start data taking in 2005

25 Future Emulsion experiment for neutrino factory ECC + fast readout system –It is possible to construct very massive detector. ECC performance preserved by modularity for large detector. –Using magnetic field: ID Emulsion works even in strong magnetic field. ECC is ready for neutrino factory

26 Industrially mass-produced emulsion film Surface protection by gelatin layer for Pb plate contact Products by Fuji Film Co. Suitable for mass production: < 2 years for production for OPERA (13.6M films) Precise mechanical size : emulsion layer thickness (~ 1  m accuracy) 50  m emulsion layer 200  m base 50  m emulsion layers 200  m base

27 Cross sectional view of an emulsion layer 30grains/100  m grain diameter ~ 0.6  m Ag grain after development dx  = 0.06  m Compton Electron Fog M.I.P. Track 100  m M.I.P. Track intrinsic tracking accuracy Intrinsic tracking resolution of the emulsion

28 Electron identification in ECC brick 2h2h 2e2e Shower detected TEST experiment at CERN PS Electron Hadron (1) Different energy loss by multiple scattering E(x)=E 0 e (-x/X0) for electrons  2 e E(x)=E 0 (1-(dE/dx)x) for hadrons  2 h (2) Detection of electromagnetic shower Requires low background track density  controlled fading Sensitive to electrons close to the Pb critical energy 5X05X0 1 mm 5 cm

29   detection and energy measurement in ECC brick Improvement for missing PT analysis  h decay mode charged particle +  0 (   ) M  = 157  24 MeV/c 2 Test experiment at CERN PS 8 GeV/c  - interaction in OPERA type ECC Example of  detection in DONUT ( Fe not suited for energy measurement) --  s from  0