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

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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)

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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.

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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)]

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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

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Multi-Anode Photomultiplier tube

[16 pixel MAPMT] [64 pixel MAPMT]

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Result of Uniformity measurement

NormaliNormalizeded

NormaliNormalizeded

RICH test at PAL

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[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

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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)

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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

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New diffuser method for uniformity and single photoelectron measurement -> quite well

Outlook

Conclusion