Uniformity Measurement of the HUniformity Measurement of the Hamamatsu 10 inch PMTamamatsu 10 inch PMT

Hiroko MiyamotoHiroko Miyamoto Dept. of PhysicsDept. of Physics

CHIBA UniversityCHIBA University

Laguna Beach2003

Why you need 2-D uniformity Why you need 2-D uniformity measurement.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.

R-guide(400R)

UV LED

Dynode

UV LED

Rotation bed

2D Measurement system

The MeasurementThe 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, 108 GainDark current ~ 300 A Noise Rate ~1kHz with 100 mV threshold. (Needs to be reduced)

108Gain

motor, function generator, digital oscilloscope,

camac, NIM,etc. controlled by 1 PC

(z,a)=(0,0)

0.06.0 4.0 5.83.8Distance from center [cm]

(z,a)=(0,0)

0.06.0 4.0 5.83.8Distance from center [cm]

0.06.0 4.0 5.83.8Distance from center [cm]

0.06.0 4.0 5.83.8Distance from center [cm]

What we have seen (preliminary though)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.

Many has yet to be done.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.