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1. A Simple Method of Uniformity Measurement and RICH R&D. 14. Oct. 200 8 C.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. 2. Contents. Motivation
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1 A Simple Method of Uniformity Measurement and RICH R&D 14. Oct. 2008 C.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
2 Contents • Motivation • Uniformity measurement of Multi-anode PMT • Mini-RICH test at Pohang Accelerator Lab • 4. Single photoelectron measurement • 5. Conclusion & Outlook
Motivation : mini-RICH detector 8×8 PMT(HAMATSU,H8500) Sliver coated Al Mirror 3 • 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
Motivation :uniformity of MAPMT [HAMAMATSU uniformity] [ Hamamatsu Method] 4 ※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. Complication and quite expensive
A Simple method Uniformity measurement : light source Diffuser1 Diffuser2 Z Z Diffuser set (x,y,z) = ( 0, 0, 340) PMT USB2000 Diffuser3 (x,y,z)=(0,1000, 375) Uniform Light X X Y Y [Blue LED (λ= 472nm)] [light intensity distribution after diffuser] 5 • A simple method • -> LED and diffuser set • - Light Uniformity have a little difference at each point -> take uniform region
Result of Uniformity measurement Normalized Normalized 7 [64 pixel MAPMT] [16 pixel MAPMT]
8 RICH test at PAL • 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 RICH 60Mev/c RICH 60Mev/c [RICH align] [Gas system] [Beam line]
Result of mini-RICH Before correction After correction(HAMAMATSU) After correction(our uniformity) 9 • Before correction, central region is high • Ring image show up by uniformity correction
Photoelectron measurement and result 10 • Two polarizer to attenuate light intensity • Calculate photoelectron of Uniformity measurement • -> [QDC channel(uniformity)] • /[QDC channel(SPE)] Polarizer 2 Diffuser2 Diffuser1 PMT Diffuser3 Polarizer 1
Conclusion & Outlook 11 Conclusion New diffuser method for uniformity and single photoelectron measurement -> quite well Outlook 1) Single photon electron measurement for 64Channel MAPMT 2) 2nd mini-RICH - Longer Radiator length - Larger acceptance Mirror (size↑, UV range reflectivity↑) - UV-extended window MAPMT