Measurement of 'intrinsic' properties

of scintillating fibers

H. Sakamoto Osaka University, Japan

A. Sato M. Yoshida Y. Kuno Osaka Univ.K. Yoshimura KEK

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

D1 TOF2D2Sci-Fi

Trigger coincidence of all counters and Sci-Fi

Data we took ADC & TDC of all counters and Sci-Fi

3m0.5m5m

•600MeV/c•700MeV/c•1Gev/c

TOF2 Sci-Fi TOF1D1

Dark box

D2

• p+　•π+ •μ+ 　　

Beam

Beam line

Sci-Fi in Dark box

D1

D2 TOF2

KEK beam test set up Ⅱ

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

PMTSci-Fi

Aluminized tape

22mm

20 fibers

These were in a dark box

•Front view

PMTSci-fi

Analysis

Average number of photo electron was estimated by fitting the sci-fi ADC spectrum to a poisson distribution.

typical sci-fi ADC spectrum

Adc count

count

Result of light yield

5000ppm has the highest light yield in tested fibers (2.6p.e.@MIP).

Light yield of 3HF concentration dependence

Ave.

# o

f p.

e.

dE/d ｘ (MeV/cm)

5000ppm3500ppm2500ppm

Only 5000ppm

350um phi

Set up for cross talk test

The differences A & B of light yield result in cross talk

•Black papers between every fiber

•Tie together every two fibers •Put black papers in between

A

B

Result of cross talk test

Cross talk Ave. # of p.e.@MIP (2.0 MeV/cm)

5000ppm 3500ppm 2500ppmOnly 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%

No evidence of cross talk

If cross talk small 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 Fitting

F=exp(A-x/L1)+exp(B-x/L2) Result

A =1.49 B =0.32 L1=7.62 L2=0.69

Attenuation Length is 7.62m.

Our waveguide of prototype is 4m clear fiber

40% loss was estimated 　　

KURARAY CLEAR-PS 1.05mmphi, Multi-Clad, S-type, Round

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 p.e.@M.I.P. 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)