February 28, 2002KOPIO Collaboration Meeting1 Status of Japan Group and Beam Catcher Contents : Status of Japan Group Progress in Beam Catcher Plan in 2002 N. Sasao / T.Nomura (Kyoto U)

February 28, 2002KOPIO Collaboration Meeting2 Status of Japan Group Member  Kyoto Univ. (N.Sasao, T.Nomura, 2 Grad.students)  KEK (M.Kobayashi, T.Taniguchi)  Kyoto U. of Education (R.Takashima) Funding Status  Japan-US Cooperation 40k$ (JFY01), 80k$ (JFY02)  Grant in Aid for Scientific Research 100k$ (JFY02), 700k$ in total (JFY2002-5)

February 28, 2002KOPIO Collaboration Meeting3 Progress in Beam Catcher Catcher Baseline  Lead-Aerogel Counter 20cm x 20cm x 5cm Aerogel (n=1.03) 2mmt Lead converter 5-inch PMT Parabolic mirror Light collecting funnel  Distributed Geometry 20/21 modules x 25 (20) layers 35cm apart in beam direction Coincidence along beam direction

February 28, 2002KOPIO Collaboration Meeting4 Progress in Beam Catcher Concept of Mini Prototype  Lead-Aerogel Counter 11cm x 11cm x 5cm Aerogel (n=1.03) 2mm/20mmt Lead converter 5-inch PMT Plane mirror No light funnel  Distributed Geometry 2 Layers (1+3 modules) 25/35cm apart in beam direction Coincidence along beam direction

February 28, 2002KOPIO Collaboration Meeting5 Progress in Beam Catcher Mini Prototype Beam Test at KEK  Test at KEK 12GeV PS Charged Beam (  /p) Up to 2 GeV/c (Ekin,proton=1.27GeV) PID by TOF and additional Aerogel

February 28, 2002KOPIO Collaboration Meeting6 Progress in Beam Catcher Item 1. Light Yield  Evaluate with  + beam  Results are 70% of expected yield 1GeV/c) Unexpected saturation effect  Need more study Aerogel’s property PMT QE, effective cathode size Alignment?

February 28, 2002KOPIO Collaboration Meeting7 Progress in Beam Catcher Item 2. Response to Proton  Proton beam as a substitution for Neutron Main difference between them is they can/cannot produce knock-on electron. If nuclear reactions being enhanced, their behavior expect to be similar.  To enhance reaction events, Increase converter’s thickness of first layer. (2mmt  20mmt) Requirement of coincidence between layers automatically enhances reactions.

February 28, 2002KOPIO Collaboration Meeting8 Progress in Beam Catcher Item 2. Response to Proton  What we expected (GEANT simulation) Thin converter 2mmt Thick converter 20mmt p n single coincidence

February 28, 2002KOPIO Collaboration Meeting9 Progress in Beam Catcher Item 2. Response to Proton Results  Rather high single hit rate Mostly 1 p.e. level Exist even if  No Aerogel tiles  Mask PMT window Any radiator remains? Secondary hits PMT?  High coincidence probability Accidental? Real effect?

February 28, 2002KOPIO Collaboration Meeting10 Progress in Beam Catcher Mini Prototype Summary  Construct Mini Prototype and Test at KEK-PS.  Measure light yield 70% of expected  Measure response to proton Both single and coincidence probabilities are higher than expected.  Secondary hits PMT directly?  Random background?  OR, this is correct?  Detailed analysis in progress

February 28, 2002KOPIO Collaboration Meeting11 Plan in 2002  Light yield study Aerogel’s optical properties  Refractive index  Transmittance Measurement with electron  Electron Synchrotron at Kyoto Uji campus (March-April)  Tabletop calibrator with Ru source and solenoid lens  Response to proton Re-test at KEK in May(?)  Prototype with final dimension Large Aerogel fabrication Optics