Thick Target Status
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Transcript of Thick Target Status
Thick Target Status
FLASH Collaboration Meeting
2003/07/25
John Belz, Dan Guest
University of Montana
Goals of Thick Target Run:
Confirm proportionality of fluorescence yield to dE/dx by:
• Comparing light yields at different shower depths to GEANT/EGS simulations.
• Comparing the light profile to simulations, at different depths in the shower.
GEANT Lateral Distribution
GEANT Lateral Distribution
GEANT Longitudinal Development
Radiation Lengths
“Gain”
0
1
1
6.7
5
7
62.8
64.5
12
14
21.6
11.0
“Gain” of Electromagnetic Showers:
Proposed Solution
• Steel “pizza box” viewed from 4 sides.
• Three XP3062’s view 20 cm diameter “core” (99.8% at 7 r.l., 97.4% at 14 r.l.)
• Single multianode PMT viewing profile.
Side View
• Recessed on downstream end to reduce light from backscatter.
FLASH Thick Target Setup
• Seven layers of alumina, each layer 2 radiation lengths
• Three PMT’s and one multi anode PMT for cross sectional view
Multianode PMTs
Light Yields: Assumptions • Assume 5 photons/meter (300-400 nm)• View 4 cm path length• Few x107 electrons pulse? (Clive)• GEANT lepton gains
Single Photomultiplier:
• Assume T-461 Entrance pupil (1 cm diameter)• 60 cm from beam (minimize 1/r2 effects)• 9x10-7 p.e./electron ~100 p.e./pulse at 14 r.l.
Light Yield: MPMT
• 1 mm x 1 cm slit• 32 pixels across 20 cm 0.5% of light in outermost slit…• ~ 0.05 p.e./pulse @ 14 r.l. • Options…
• More intense beam?• View < 20 cm profile?• …
To dos…
• Understand mods to thin target “doghouse” necessary to view 20 cm core.
• Can we boost light for lateral measurement? Beam options?
• MPMT readout?
• Vessel manufacture; UM student(s) in collaboration with C.O.T.
• Start talking about beamline insert.