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Study of compact emulsion spectrometer
for identification of neutrino/anti-neutrino
interaction
061209 OPERA emulsion workshop @ Nagoya Univ.
Chika Fukushima Toho University
Toho Univ. ,Aichi Univ. of EducationA,Kobe Univ.B
Satoru Ogawa, Mitsuhiro Kimura, Hiroshi Shibuya,Koichi KodamaA, Toshio HaraB
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Introduction
Only emulsion detector achieved identification of interaction by detection.
+ magnet: to distinguish anti-neutrino() interaction
+ New technique → emulsion : large-scale production by automatic coating data taking : high speed automated track selector
ECC(Emulsion Cloud Chamber) : multilayer detector of emulsion and metal plate(lead etc.)
Emulsion detector(ECC) can identify neutrino/anti-neutrino interaction.
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Motivation
ECC ( multilayer of emulsion and lead plate ) + magnetic fieldthis detector has large amount of material
★ bending of magnet must be dominated scattering.★ short flight length before electromagnetic shower
Compact emulsion spectrometer less amount of substance Can this detector be charge identification
after production charged lepton immediately?If that can be, how thickness do we need ?
Such a detector should become important in future neutrino experiments.
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thickness of spacer : 15mm
total chamber length : 30mm
nonmagnetic
screw
emulsion film
beam
TAC (plastic base) : 200memulsion : 44m
It’s new emulsion which has same crystal
size → automatic coating ・ large scale of
production ・ regular thickness
small amount of substance
acrylic plate 200m
or polystyrene 40m
support
vinyl chloride plate(air gap at central part)
Compact emulsion spectrometer(structure)
acrylic plate
“OPERA film” (emulsion: AgBr crystal)
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B
248mm
248m
m
depth 244mm
N d FeB compact permanent magnetmagnetic field 1 Tesla (1.057[T] at the center)
1.0T
0-100 100Z[mm]
distribution of magnetic field along the beam direction
Good point using permanent magnet is:☆ compact ( no need space )☆ no electric power is needed
0%
-1%
1%
2%
-2%
relative error
distribution of magnetic field in middle of magnet(z=0)
1 Tesla permanent
magnet
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Me
A stack has total length of 30mm.
reference beam in each stack2.0GeV/c +[no magnet]3000/cm2
stack # support beam momentum ( ± ) and densitylength of stack
stack1acrylic plate 200m
0.5 、 2.0GeV/c [4 beams] :
1000/cm2 for each beam
30mm
stack2acrylic plate 200m
1.0GeV/c [2 beams] :
1000/cm2 for each beam
30mm
Dec. 7, 2005 KEK-PS T1 line
Beam Exposure
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s = 0.3 B L2/(8p[GeV/c])
L
L/2 L/2
S
L = 0.03[m] in this study
d
d = 2s
sagitta s versus stack length L
L(mm) 30s(m) 39.8d(m) 79.6
1.0GeV/c
L(mm) 30s(m) 79.6d(m) 159.1
L(mm)
30
s(m) 19.9
d(m) 39.8
0.5GeV/c
2.0GeV/c
B = 1.057[T]
sagittaAlignment among three plates is performed with reference beam.
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L[mm] 30
s[m] 39.8
Expected sagitta s
ref.
ref.mean: -37.6[m]mean: 38.1[m]
Sagitta 1.0GeV/c (stack2)
Scan area = 2 cm x 2 cm
Preliminary results
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L[mm] 30
s[m] 79.6
Expected sagitta s
mean: -78.9m
mean: 79.0m
Sagitta 0.5GeV/c (stack1) preliminary
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L[mm] 30
s[m] 19.9
Expected sagitta s
mean: -19.7m
mean: 19.6m
Sagitta 2.0GeV/c (stack1) preliminary
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0.5GeV +0.5GeV 1.0GeV +1.0GeV -
2.0GeV -
2.0GeV +
More than 5 charge determination has been achievedfor 0.5, 1.0, 2.0 GeV/c ±.
superposition of 0.5, 1.0, and 2.0GeV/c ±
preliminary
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Relation between sagitta and momentum(1/p) preliminary
Horizontal axis is inverse of ± momentum.
and vertical axis sagitta for each inverse momentum.
I’m preparing a paper.
Momentum resolution is about 14% on average,
mostly due to a multiple scattering.
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● Slim spectrometer :3-layer low density structure ,30mm thick ,with permanent magnet of 1 Tesla.
● Slim spectrometer was exposed to 0.5, 1.0, and 2.0GeV/c ±
at KEK-PS T1 line. • The average of momentum resolution was found to be about 14%, mostly due to multiple scattering.
conclusions
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OutlookThe relative error (that is, ) is
expected to be :pp
pp
ss
+~ 0.14 0.029p [GeV/c]
In the case of p = 10GeV/c, ~ 0.32. pp
Therefore, probability of the charge mis-identification
for a lepton with p = 10GeV/c would bearound 0.2%.