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To Investigate: Simulate in RICH Raja started this Simulated scintillation from MIPs (1 ph/cm) Showed spatial hit distributions on PMTs Integrated hit ratio PMT/MAPMT ~ 3.5 Measure scintillation light yield from radiator gas in lab. Scintillation in C4F8O ?. Problem:
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To Investigate: Simulate in RICH Raja started this Simulated scintillation from MIPs (1 ph/cm) Showed spatial hit distributions on PMTs Integrated hit ratio PMT/MAPMT ~ 3.5 Measure scintillation light yield from radiator gas in lab Scintillation in C4F8O ? • Problem: • Creates isotropic background under Cherenkov ring image • If large light yield, would be a problem • mainly for PMT system, where “pixel” is large and Cherenkov yield is small (~10 pe/trk)
What is known? …noble gases, freons scintillate Measurements (1) big small small big BUT…
HADES Measurements: Looked at several gases in UV Used different projectiles (alpha, p, O16), all stopping, but saw no appreciable difference I integrated these spectra to get estimates in table HERA-B Measurements: C4F10 ~ Air ~ Ar/(4-5) in VIS Estimate a “few” scintillation hits / event in full RICH, or bkgd of ~0.2 hits / trk Measurements (2) “small” “large” ~0.25 ph/cm for us ?
The Plan: Build a Chamber [IP] Counting experiment Excitation: alpha (stopping) Ea ~ 5.5 MeV, Range ~ 1.5 cm For different gases (C4F8O, N2, Ar, …) as a fn of pressure Signal decreases as P increases Measurement relative to N2 Take out systematics Normalize DW by MC Refinements: Use filters/mono/CR/LIF/… Measurements (3) PMT XP3312/B window alpha source vacuum chamber
