1. KEK beam test H. Sakamoto

2. Purpose To optimize a concentration of the second dopant for scintillating fibers KEK beam test to study light yields for various concentrations Summary

3. Sci-fi tracker 30cm Edge of layer Requirements for scintillating fiber Diameter ： 350um Core : 330um Clad : 6% of 350um No cross talk Small light yield due to small fiber High Q.E. photo detector VLPC (Visible Light Photon Counter ） Sensitive region ～ 500nm ３ HF fiber mixed with wavelength shifter To the photo detector Clear fiber Sci-fi station Layout of Sci-fi station

4. Purpose for the beam tests We tested the light with two difference tests to study the light yield with realistic components of 3HF concentration dependence First time (T553-1): calibrated the gain of pmt with 1 p.e. Second (T553-2) : 〃 with more p.e. ( ～ 20p.e.) T553 (this time) T542 (last year) SciFi length 40cm 20cm Mirror aluminized mirror aluminized mylar Connection MICE connector acryl board Clear fiber w/ and w/o 4m no PMT R7411U-40MOD R7899-MOD

5. Scintillating fibers tested Kuraray SCSF-3HF ; 0.35mm-phi, multi-clad, s-type In this beam test, pT(2%) scifi was also tested. pT(1%) + 3HF(5000ppm) pT(2%) + 3HF(5000ppm) pT(1%) + 3HF(3500ppm) pT(1%) + 3HF(2500ppm) pT(1%) + 3HF(4500ppm) pT(1%) + 3HF(7500ppm) pT(1%) + 3HF(10000ppm) pT(2%) + 3HF(10000ppm)

6. Attaching SciFi with MICE conn. Attached the SciFi and clear fibers with MICE conn. Clear fibers for pmt ’ s gain calibration Clear fiber (1.05mmΦ) SciFi (0.35mmΦ): 14fibers SciFi Clear fib

7. Scintillating fiber Connecting the SciFi into the hole of MICE connector

8. Fixing by optical cement Fixed the SciFi with optical cement

9. Q.E. of VLPC & 3HF emission spectrum 3HF emission spectrum 520nm Quantum efficiency of VLPC 520nm

10. Quantum efficiency

11. Photo multiplier tube We used the photo multiplier tube instead of VLPC.  Hamamatsu R7411U-40MOD GaAsP (Gallium-Arsenic-Phosphorous) 8mm diameter 10 stage Head-on Type HV= -850V

12. Set up T542 (last year) Side view PMT Sci-Fi Aluminized tape 22mm 20 fibers These were in a dark box Front view PMT Sci-fi

13. KEK beam test set up Ⅰ D1 TOF2 D2 Sci-Fi Trigger coincidence of all counters Data we took ADC & TDC of all counters and Sci-Fi 1.5m 4m 0.6 GeV/c 1.2 Gev/c TOF2 Sci-Fi TOF1 D1 Dark box D2 p + π + Beam D3

14. Set up (T553) Beam area Dark box

15. Set up (T553) In the dark box D1 D2 SciFi and support

16. Setup (T553) mirror pmt SciFi SciFi and its support gide before setting in the dark box

17. Aluminized mirror SciFi Mirror

18. PMT (R7411U-40MOD) SciFi PMT

19. Close up of SciFi 14 fibers were arranged into 420um bitch

20. Arrangement of Scifi For single layer : 14 fibers For double layer : 3 fibers for up and 4 for down 420um

21. T553-1 (first test) Gain calibration -1 calibrated the PMT ’ s gain by 1 p.e. Injected the LED light adjusted as 1 p.e. to the cathode surface of the PMT. 1 p.e. was determined with the ratio of 0 p.e. and 1 p.e. But this measurements was not worked Not good S/N To the second test  with higher p.e.#

22. The result : Light yield T553-1 (first time) These are not p.e. but the relative values are meaningful. 5000ppm has the highest light yield in tested fibers. 1. 5000 -1% 2. 4500 -1% 3. 10000 -1% 4. 2500 -1% 5. 5000 -2% 6. 3500 -1% 7. 7500 -1% 8. 10000 -2%

23. T553-2 (second test) Gain calibtion -2 Adjusted the LED to about 20 p.e. P.e.# was estimated by ((MEAN)/(RMS))^2

24. Beam stability Stability of beam momentum by Time of flight of 0.6 (Gev/c) proton

25. Monte Carlo Simulated 1.2 (GeV/c) data for proton and pion Histgram (red) = MC Plot w/ err = data Pion Proton

26. Result of light yield P.e.# (estimated by MC) Light yield of 5000ppm-(1%) Light yield (5000-1%) = 8 p.e. @MIP

27. Result of light yield Light yield of 2500ppm-(1%) P.e.# (estimated by MC) Light yield (2500-1%) = 6.5 p.e. @MIP

28. The result Single layer && 4m clear fiber 5000ppm-1%2500ppm-1%

29. The result Double layer && NO clear fiber 5000ppm-1% 2500ppm-1%

30. The result Double layer && 4m clear fiber 5000ppm-1% 2500ppm-1%

31. 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 Single layer 5000ppm-1% : 8 p.e. (3 p.e.) 2500ppm -1%: 6.5 p.e. (3 p.e.) Double layer 5000ppm-1%: 10 p.e (4.5 p.e.) 2500ppm-1%: 8 p.e. (4.5 p.e.)

32. Summary We studied the light yield of scintillation fibers mixed with 3HF as a secondary dopant with realistic component. We studied the light yield with some conditions. w/ and w/o 4m clear fiber Single and double layer The result of light yield pT(1%) + 3HF(5000ppm) has the highest light yield in any conditions.