Report from Japan Group Beam Catcher

1
Report from Japan Group Beam Catcher

• N. Sasao / T. Nomura (Kyoto U.)
• Contents
• Status of Japan Group
• Progress in Beam Catcher
• Test of Aerogels Light Yield
• Beam test with 60MeV electrons
• Optical properties of Aerogel tile
• 2nd prototype to study response to protons

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Institutional Issues Status of Japan Group

• Member
• Kyoto U.N.Sasao, T.Nomura, T.Sumida (M2),
  H.Morii (M1)
• KEKM.Kobayashi, T.Taniguchi
• Kyoto U. of EducationR.Takashima
• Funding in this year
• Japan-US Cooperation 80k (JFY02)
• Grant in Aid for Scientific Research 100k
  (JFY02, 700k in total till JFY2005)

Two new graduated students Our main
man-power!!
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Progress in Beam Catcher Test of Basic
Performance

• Proof-of-Principle module gt 1st Mini Prototype
• Lead-Aerogel Module
• Aerogel n1.03
• Stack of 4 tiles (11cm x 11cm x 1.1cm each)
• 2mm/20mmt Lead converter
• 5-inch PMT
• Plane reflecting mirror
• No light funnel
• Tested in Dec.,2001 at KEK
• 70 of expected light yield
• Unwanted accidentals hid the proton reaction
  behavior

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Futher study on Aerogels Light Yield Test with
60MeV electrons

• Electron Strecher Ring in Uji-campus, Kyoto U.
• Beam energy 60MeV
• Slow extraction by RF knock-out method
• Easy to use (Need daily-basis tuning only)

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Futher study on Aerogels Light Yield Light
Yield and Ring Image

• Photoelectron yield I?(1-1/n2b2)

• Ring Image

MC
assuming n1.03and normd at 1GeV/c
60MeV e-
1-2GeV/c p (KEK)
(10 discrepancy comes from mis-tuning of light
path length in MC)
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Aerogelss Light YieldTransmittance of Aerogel
Tile

• Aerogels optical properties determine light
  yield
• Transmittance (Photo-spectrometer Shimadzu
  MPS-2000)
• Described with absorption and scattering(s) Rayle
  igh (?1/l4) additional scattering, for ex., Mie
  (?1/l)

• Obtain similar results to those in HERMESs paper
• P192, P20.01mm4
• Dirty surface causes additional scattering
  effect, which has different wavelength dependence

Bad c2
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Response to Proton 2nd Mini Prototype

• To study response to protons
• PMT must be far/shieldedfrom interaction
  point(experience from test in Dec., 2001)
• New features
• 5-inch PMT, located at 35cm apart from beam line
• An-isometric parabolic mirror z x2/4fx
  y2/4fy, fx?fy
• Test at KEK in coming September

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Progress in Beam Catcher Summary

• Further test with 1st mini prototype
• Light yield study with 60MeV electron at Kyoto
  U., Uji
• Ring size/width are OK
• Light yield is 10-20 smaller than MC expected
• Transmittance of Aerogel tile
• As expected, but care must be taken when handling
  tiles
• Construct 2nd mini prototype
• To study response to protons
• Test at KEK in September
• New optical element (an-isometric parabola) an
  exercise to fabricate real optics