1. Uniformity Measurement of the Hamamatsu 10 inch PMT Hiroko Miyamoto Dept. of Physics CHIBA University Laguna Beach2003

2. Why you need 2-D uniformity measurement. Tube response are actually quite NOT uniform. “10 inch” tube would not imply collection area of 10 inch diameter. The sensitivity table (X,Y) or (R,  ) gives a redundancy in understanding the DOM angular response.

3. R-guide(400R) UV LED Dynode UV LED Rotation bed 2D Measurement system

6. The Measurement The Light Source – UV (380 nm) Nichiya LED (220  driving) The Pulse is formed by the Agilent Func. Generator (100 nsec) PMT – Hamamatsu 10 “ –02 tube. (The most favorite choice for the IceCube) HV – 1750 V, 10 8 Gain Dark current ~ 300  A Noise Rate ~1kHz with 100 mV threshold. (Needs to be reduced)

7. 10 8 Gain

8. motor, function generator, digital oscilloscope, camac, NIM,etc. controlled by 1 PC

10. (z,a)=(0,0) 0.06.04.05.83.8 Distance from center [cm]

11. (z,a)=(0,0) 0.06.04.05.83.8 Distance from center [cm]

12. 0.06.04.05.83.8 Distance from center [cm]

13. 0.06.04.05.83.8 Distance from center [cm]

14. What we have seen (preliminary though) The uniformity shows variance by 20 % even in the central region (10 cm diameter) The 2d sensitivity behavior does not exhibit spherical symmetry.

15. Many has yet to be done. Further Noise Reduction must be done. (Currently 1k Hz with 100 mV threshold) LED Pointing calibration needs to be made with great care. LED emission angle dependences must be studied. Needs to survey entire photo-cathode surface – Rearrangement of the PMT housing is necessary. Needs to develop DAQ to control CAMAC/GPIB/Stepping-Motor on the completely unified foundation. Needs to study a possible tube-by-tube variance.