1 nufact’01 wg1 : neutrino oscillation physics may 24-30, 2001 an appearance experiment to search...
TRANSCRIPT
1
NuFact’01
WG1 : Neutrino Oscillation PhysicsMay 24-30, 2001
An appearance experiment to search for - oscillations
in the CNGS beam CNGS1
Oscillation Project with Emulsion-tRacking Apparatus
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
• m2 = (1.5 - 5) x10-3 eV2 ( SuperK) Mtarget ~ 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”)
spectrometerMagnetised Iron Dipoles
Drift tubes and RPCs
target and decay detectorEach “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 (10X0)
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 cmPb 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
10X0 ( 56 emulsion films ) 8kg for each brick
12.5cm
235k bricks for 3 supermodules
Similar packing was usedfor E531,CHORUS,etc. DONUT did not use thispacking 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
1mmFe plate
Emulsion film
7
The First detection in ECC • Iron-Emulsion ECC target
– 50cm x 50cm x 7cm(47 Iron plate : 2.7X0)– Topology, momentum and e-ID in ECC
• Beam– 3.5x1017 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 multipli
city at TT events. • Tau and charm events
– 6 tau events– 2 charged and 2 neutral charms
8
6th tau event in DONUT ECC
cGeV
cGeV
cGeV
/208.09.18
/401.034.3
/132.077.7
7.2079.6
16.171.0
62.396.1
9
Momentum measurement
in DONUT ECC
Momentum measurementby multiple scattering
Consistent result withmomentum measuredby 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
11Nov. ‘99
CHORUS Phase II data taking
12
Netscan (Chorus phase II)
1.5 mm
1.5 mm
All track segments(6k hits)
8 plates overlappe
d
6.3 mm
Yellow : UpstreamRed : Downstream
13
1.5 mm
1.5 mm
Small impact
parameter
Netscan (Chorus phase II) Yellow : Upstream
Red : Downstream
CC D0
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 tim
e.
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: 20cm2/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
~ 32000 NC+CC
~ 240 CC
for SuperK best fit : sin2 2 = 1 m2 = 3.2x10-3 eV2
The CNGS beam
Shared SPS operation 200 days/year 4.5x1019 pot / year
Nominal beam
( m-2 / pot) 7.45x10-9
CC / pot / kton 5.44x10-17
< E > ( GeV ) 17
(e + e) / 0.85 %
/ 2.0 %
prompt negligible
19
AnalysisstepsBrick finding
Trigger
Vertex location
Decay search“long” or “short”
decays
decay mode
Kinematics
events
Classifyas / e
yes
no
Electronic detectors
Emulsions
Emulsions
Electronic detectors
eat 1ry vtx ? CHORUS
DONUT
20
Summary of detection efficiencies(in % and including BR)
Decay mode DIS long QE long DIS short Overall*
e 3.0 2.6 1.3 3.7 2.7 2.8 - 2.7 h 2.2 2.8 - 2.3Total 8.0 8.3 1.3 8.7
* 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)
e h Total
Charm production 0.15 0.03 0.15 0.33e CC and 0 0.01 - - 0.01Large scattering - 0.10 - 0.10Hadron reinteractionswith kink topology
- - 0.10 0.10
SubTotal 0.16 0.13 0.25 0.54
Charm production 0.03 - - 0.03e CC and 0 «0.01 - - «0.01
SubTotal 0.03 - - 0.03
Total 0.19 0.13 0.25 0.57
Lo
ng
dec
ays
Sh
ort
de
cays
22
m2 = 1.2x10-3 eV2
at full mixing
sin2 (2) = 6.0x10-3
at large m2
(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
(2.25x1020 pot)
• Average target mass = 1.8 kton
(accounting for mass reduction with time, due to brick removal for analysis)
Expected events
events
decay m2 (10-3 eV2 ) b.g.1.5 3.2 5.0
e 1.7 7.7 18.5 0.19
1.3 5.7 13.8 0.13
h 1.1 4.9 11.8 0.25
Total 4.1 18.3 44.1 0.57
m2 (eV2)
eve
nts
e
xpe
cte
d in
5 y
ea
rs
(log
scal
e)
24
Summary and conclusionsfor OPERA
• Experience with E531, CHORUS, NOMAD and DONUT
• OPERA : appearance and appearance and mm2 2 measurement at CNGSmeasurement 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 experimentfor 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.
tee and ,,,,
ECC is ready for neutrino factory
26
Industrially mass-produced emulsion film
Surface protection by gelatin layerfor 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)
50m emulsion layer
200m base
50m emulsion layers
200m base
27
Cross sectional view of an emulsion layer
30grains/100mgrain diameter ~ 0.6m
Ag grain after development
dx
= 0.06mCompton Electron
Fog
M.I.P. Track
100m
M.I.P. Track
intrinsic tracking accuracy
Intrinsic tracking resolution of the emulsion
28
Electron identification in ECC brick
2h
2e
Shower detected
TEST experiment at CERN PS
Electron
Had
ron
(1) Different energy loss by multiple scattering E(x)=E0e (-x/X0) for electrons 2
e
E(x)=E0(1-(dE/dx)x) for hadrons 2h
(2) Detection of electromagnetic shower Requires low background track density controlled fading Sensitive to electrons close to the Pb critical energy
5X0
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/c2
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