A Study of π Capture Simulation for PRISM

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Measurement of 'intrinsic' properties
of scintillating fibers
H. Sakamoto
Osaka University, Japan
A. Sato M. Yoshida Y. Kuno
K. Yoshimura KEK
Osaka Univ.
Purpose

To optimize a concentration of the secondary
dopant (3HF) for scintillating fibers

KEK beam test to study light yields & cross talk
for some different concentration

Attenuation length of a clear fiber

Light yield loss

Summary
Beam test @ KEK

To study the light yields and cross talk
of 3HF concentration dependence

Scintillating fibers tested:
Kuraray SCSF-3HF ; 350um-phi, multi-clad, s-type
 Primary (pT) + Secondary (3HF;5000ppm)
 Primary (pT) + Secondary (3HF;3500ppm)
 Primary (pT) + Secondary (3HF;2500ppm)
 No primary
+ Secondary (3HF;5000ppm)
KEK beam test set up Ⅰ
TOF1
D1
Sci-Fi
TOF2
D2
Beam
• p+ •600MeV/c
•π+ •700MeV/c
•μ+ •1Gev/c
Dark
box
5m
0.5m
3m
Trigger
 coincidence of all counters and Sci-Fi
Sci-Fi
TOF2
D2
 Data we took D1
 ADC & TDC of all counters and Sci-Fi

KEK beam test set up Ⅱ
Sci-Fi in
Dark box
Beam line
D1
D2
TOF2
3HF emission spectrum & Q.E. of VLPC

3HF emission spectrum
520nm

Quantum efficiency of VLPC
520nm
Photo multiplier tube

We used the photo multiplier tube instead of VLPC.

Hamamatsu R7899MOD

Extended Green
Photocathode

1 inch diameter

10 stage

Head-on Type

Prismatic Window

HV= -1800V
Set up of scintillating fiber
•Side view
•Front view
22mm
20 fibers
Sci-Fi
Sci-fi
Aluminized tape

These were in a dark box
PMT
PMT
Analysis
 Average number of photo electron
was estimated by fitting the sci-fi ADC spectrum
to a poisson distribution.
typical sci-fi ADC spectrum
count

Adc count
Result of light yield

Light yield of 3HF concentration dependence
Ave. # of p.e.
350um phi
5000ppm
3500ppm
2500ppm
Only 5000ppm
dE/dx(MeV/cm)

5000ppm has the highest light yield in tested fibers ([email protected]).
Set up for cross talk test

The differences A & B of light yield result in cross talk
A
•Black papers between every fiber
B
•Tie together every two fibers
•Put black papers in between
Result of cross talk test

Cross talk
 Ave. # of [email protected] (2.0 MeV/cm)
5000ppm
3500ppm
2500ppm
Only
5000ppm
Set up A
2.60
2.24
2.24
1.86
Set up B
2.78
2.37
2.31
2.00
(B-A) /A
7%
6%
3%
8%
If cross
talk

small
No evidence of cross talk
large
very
small
Conclusion from the beam test

We tested scintillating fibers of different 3HF
concentration.

We used green sensitive PMTs in stead of VLPC.

The result of light yield test
 5000ppm has the highest light yield
of 2.6 p.e. @ MIP.

The result of cross talk test
 No evidence of cross talk can be seen.
Atte. length of clear fiber Ⅰ
Set up
 Clear fiber:
KURARAY CLEAR-PS
 Round, Multi-Clad, S-type
 Pulser:
 Duration: 1nsec
 Period: 10msec
 Pulse height: -5.5V
 Silicon photo diode
 ORIEL Model 70313

Atte. length of clear fiber Ⅱ

 Result
Fitting
 A =1.49
F=exp(A-x/L1)+exp(B-x/L2)
 B =0.32
 L1=7.62
 L2=0.69
KURARAY CLEAR-PS
1.05mmphi, Multi-Clad
, S-type, Round

Attenuation Length is
7.62m.

Our waveguide of
prototype is 4m clear fiber
 40% loss was estimated
Summary

We studied the light yield and cross talk of scintillation
fibers mixed with 3HF as a secondary dopant.

Scintillating fibers tested: Kuraray SCSF-3HF
 pT+5000ppm, pT+3500ppm, pT+2500ppm, only5000ppm
 Light yield : pT+5000ppm has the highest light yield
of 2.6 [email protected]
 Cross talk : No evidence of cross talk can be seen.

We also studied the attenuation length of the clear fiber.
 40% loss was estimated in 4m (in the prototype)
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