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 1

2. 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

3. 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

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. 4 Motivation :uniformity of MAPMT [HAMAMATSU uniformity] [ Hamamatsu Method] Complication and quite expensive

5. PMT Uniform Light Diffuser 2 Diffuser 1 Diffuser 3 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

6. H8711 Pixel4*4 Effective area [mm 2 ]18.1*18.1 H8500 Pixel8*8 Effective area [mm 2 ]49*49 6 Multi-Anode Photomultiplier tube

7. [16 pixel MAPMT] [64 pixel MAPMT] 7 Result of Uniformity measurement Normalied Normalized

8. RICH test at PAL 8 [Beam line] [RICH align] 60Mev/c 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. 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. 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)]

11. 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