February 28, 2002 KOPIO Collaboration Meeting 1

Status of Japan Groupand Beam Catcher

Contents : Status of Japan Group Progress in Beam Catcher Plan in 2002

N. Sasao / T.Nomura (Kyoto U)

February 28, 2002 KOPIO Collaboration Meeting 2

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, 2002 KOPIO Collaboration Meeting 3

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, 2002 KOPIO Collaboration Meeting 4

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, 2002 KOPIO Collaboration Meeting 5

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, 2002 KOPIO Collaboration Meeting 6

Progress in Beam Catcher Item 1. Light Yield

Evaluate with + beam Results are

70% of expected yield (Npe=6 @ 1GeV/c)

Unexpected saturation effect Need more study

Aerogel’s property PMT QE, effective cathode size Alignment?

February 28, 2002 KOPIO Collaboration Meeting 7

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, 2002 KOPIO Collaboration Meeting 8

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, 2002 KOPIO Collaboration Meeting 9

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, 2002 KOPIO Collaboration Meeting 10

Progress in Beam Catcher Mini Prototype Summary

Construct Mini Prototype andTest 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, 2002 KOPIO Collaboration Meeting 11

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