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A Simple Method of Uniformity Measurement and RICH R&D
14. Oct. 2008C.W. Son* J. KIM, J.G. YI, H.Y. LEE, K.E. Choi, H.D. Son, K.H. Kim
In-Kwon Yoo
Department of Physics, Pusan National University Heavy Ion Physics Experiment LAB
1
1. Motivation
2. Uniformity measurement of Multi-anode PMT
3. Mini-RICH test at Pohang Accelerator Lab
4. Single photoelectron measurement
5. Conclusion & Outlook
2
Contents
8×8 PMT(HAMATSU,
H8500)
3
Motivation : mini-RICH detector
- Mini-RICH detector consists of a gas radiator and a concave mirror, a multi-anode PMTube H8500 by HAMAMATSU
- Multi-anode PMTube has different sensitive -> need Uniformity measurement
Sliver coated Al Mirror
※Uniformity- The uniformity is a fundamental characteristic of a photo multiplier. Since each channel has its own dynode-anode system, its sensitivity fluctuates each other.
4
Motivation :uniformity of MAPMT
[HAMAMATSU uniformity][ Hamamatsu Method]
Complication and quite
Complication and quite
expensiveexpensive
PMT
Uniform Light
Diffuser2
Diffuser1
Diffuser3
X
Y
Z Diffuser set
USB2000
X
Y
Z(x,y,z) = ( 0, 0, 340)
(x,y,z)=(0,1000, 375)
[Blue LED (λ= 472nm)]
5
A Simple method Uniformity measurement : light source
[light intensity distribution after diffuser]
- A simple method
-> LED and diffuser set
- Light Uniformity have a little difference at each point -> take uniform region
H8711Pixel 4*4
Effective area [mm2] 18.1*18.1
H8500Pixel 8*8
Effective area [mm2] 49*49
6
Multi-Anode Photomultiplier tube
[16 pixel MAPMT] [64 pixel MAPMT]
7
Result of Uniformity measurement
NormaliNormalizeded
NormaliNormalizeded
RICH test at PAL
8
[Beam line] [RICH align]
60Mev/c
60Mev/c
RICH
RICH
[Gas system]
- Pohang Accelerator Lab -> 60MeV/c electron
- Our gas system consists of a compress and an air tank , regulator
- We used nitrogen gas
-> Nitrogen gas more effect rather than air which have moisture
9
Result of mini-RICH
- Before correction, central region is high
- Ring image show up by uniformity correction
Before correction After correction(our uniformity) After correction(HAMAMATSU)
10
Photoelectron measurement and result
PMT
Polarizer 1
Polarizer 2
Diffuser2
Diffuser1
Diffuser3
- Two polarizer to attenuate light intensity
- Calculate photoelectron of Uniformity measurement
-> [QDC channel(uniformity)]
/[QDC channel(SPE)]
Conclusion & Outlook
2) 2nd mini-RICH
- Longer Radiator length
- Larger acceptance Mirror
(size↑, UV range reflectivity↑)
- UV-extended window MAPMT
1) Single photon electron measurement for 64Channel MAPMT
11
New diffuser method for uniformity and single photoelectron measurement -> quite well
Outlook
Conclusion