LUXE SAS Meeting March 21, 2022
Sasha: Radiation Dose for Tracker
- Radiation dose in Crate with R/O electronics next to beam on floor level, lead wall around it
- 0.6 Gray per year on typical operation, almost uniform dose
- Neutron fluence 6e3/cm^2 per BX, ~6e11 per year, tolerable for FPGA
- Summary: Most of electronics should survive
- Louis asks about origin of particles: Most are coming from the dump, photons from nuclear reactions
- Louis mentions electronics could potentially put electronics inside support structures since particles are coming from dump, not from the window
- Louis asks about where electronics for calorimeter will be placed … doesn’t seem to be very clear yet
Shan: Background from the Dump --- ECAL in e-laser mode
- Without dump acceptable background; beam dump introduces significant BG
- Mixed monoenergetic positron with local background (Louis’ method), compare ratio ratio between background on signal and signal only; should be <1.5 but is larger than 3 now.
- Summary: Need to implement further protection for ECAL from background
- Louis asks about materials iron/concrete
- Halina: We don’t have knowledge about fluctuations in background
- Louis: Exclude from analysis areas where background is high, reassess reconstruction based on restricted readout area?
- Part of background coming from wall? Figure out where particles are coming from!
Arka: Neutron Absorber for Tracker
- Reduce neutrons coming from ebeam dump
- Selected particles only from dump, air and vac exit window
- Positron side (1st layer 1st stave): 33% less neutrons with absorber; fewer high-energy neutrons; majority of neutrons coming from dump
- 43%, 53%, 52% fewer elecs, positrons, photons with neutron absorber
- Timing distribution (time-of-arrival): Readout time of ~ 1000 ns …. 75% of low-energy neutrons will arrive later, we can get rid of them by temporal gating
- Louis asks about origin of particles, relative distributions on slide 6 don’t add up: Arka mentions that some particles are coming from the tracker itself.
- Louis: What are we expecting the neutron to do in the tracker? Fake signal and damage to electronics.
- Sasha: Photons are coming from everywhere. Don’s see a lot of particles from beam dump except for neutrons.
- Halina asks about missing particles in ratio plots. Almost no electrons/photons from dump/air/window. Where are missing particles coming from? 2D plots show: calo backplane, ….
- Halina: Photon timing seems to indicate that they are not activated from neutrons.
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