1. Basic Measurement of the Hamamatsu 10 inch PMT at –40 degree –40 degree Hiroko Miyamoto Dept. of Physics CHIBA University Angular Response of 10inch PMT for IceCube Hiroko Miyamoto Dept. of Physics Chiba University

2. Contents What we can learn from 2D measurement. Improvement of measurement system. Results. Summary.

3. What you learn from 2D measurement. Tube angular response (uniformity). Actual collection area of PMT (“10 inch” tube would not imply collection area of 10 inch diameter.) The sensitivity table (X,Y) or (R,q) gives a redundancy in understanding the DOM (Digital Optical Module) angular response.

4. R-guide(300R) UV LED Dynode UV LED Rotation bed 2D Measurement system

5. Improvements of measurement systems.

7. Measurement set up (including improvement) Expand the measurement region(23 cm diameter, 10 cm longer than that of previous set up, covering almost whole sensitive region of PMT surface) Measurement of PMTs with magnetic shield has been possible.

8. 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 R7081 “ –02 tube. (The most favorite choice for the IceCube) HV – 2000 V, 5E7 Gain Dark current ~ 404  A Noise Rate ~220 Hz with 50 mV threshold.(Depending on time of PMT being kept inside dark) 30photons/shots, corresponding the average of 3000 shots.

9. 10 8 Gain

10. N Org rotate - + F

11. N Org rotate N Org rotate - + F

12. N Org rotate B - + - + F

13. N Org rotate F

14. N Org rotate F

15. N Org rotate F

16. N Org rotate F

17. N

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19. N

20. What we have seen The uniformity shows variance by 40 % in the measurement region. The 2d sensitivity behavior does not exhibit spherical symmetry. The effect of magnetic field remarkably could be seen in the area of vertical to magnetic field (which is defined as azimuthal angle = 0, from East to West on our set up) without B shield.