Barrel HCal Meeting
ePIC Barrel HCal meeting, 11/14/2014. https://indico.bnl.gov/event/25597/
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TDR status
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discussion of Megan’s slides (cf. pTDR on Zenodo: https://zenodo.org/records/13985549)
- slide 3: sparks at end points: jets with single particle
- Derek will ask John about this
- soon we will have the machinery to recreate these plots
- slide 4
- diurnal patterns
- probably not diurnal since hall will be air conditioned
- instead will see fluctuations from AC units coming on/off
- those should be small; for sPHENIX in Run 2023, the per sector average temperatures of all sectors for all LED runs taken were within 20.0 and 21.5 C. So the upper limit of these fluctuations is +/- 0.75 C. Most of that range comes from a position dependence (top sectors have higher T than bottom sectors) The actual per sector fluctuations are much smaller than 0.75 C.
- temperatures will be measured, and then gain changes will be corrected by known gain T coefficient
— in principle could also try to use LED to account for this, but LEDs will have their own instability
- those instabilities could in principle be monitored by a PIN diode; but in the current design where each tile has
its own LED there seems to be no good way to do that
- SEUs
- issues like this only seemed to affect the interface boards in sPHENIX
- those are not part of the design for ePIC (electronics will be completely different)
- SiPMs
-comparing neutron fluxes, they are similar:
- sPHENIX: 1e9 - 1e10 cm^-2 in 5 years (https://indico.bnl.gov/event/5961/contributions/27611/attachments/22408/31467/AidalaSiPMs_DirectorsReviewv2.pdf)
- ePIC: 1e8 - 1e9 cm^-2 per run:
- Here’s a (ca. May 2023) set of slides on the accumulated neutron dose from Alex:
https://indico.bnl.gov/event/19524/#8-collision-related-rates-and
https://indico.bnl.gov/event/19524/contributions/76511/attachments/47542/80662/Jentsch_dosimetry_ePIC_May_16_2023.pdf
- And here's the wiki page on backgrounds... https://wiki.bnl.gov/EPIC/index.php?title=Background
- plots with no supporting text:
- Figs. 8.121, 8.122: they are for backward calorimeter, not ours
- other plots: since we have not completed writing, there are plots in there that have no description in the text
Prototype status and plans
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tiles
- accounting of B25 tiles settled: there should be six sectors worth of them (i.e. 120).
- still have not been able to locate them
pigtail cables (SiPM board to H2GCROC)
- test of signal attenuation as a function of length: Norbert
- ordered 50 cm cables from Digikey
- delivery soon
- ordered longer cables (up to 500 cm) from a company in Taiwan (Golden Bridge)
- 12-16 weeks lead time
- prototype assembly: Eric (see slides)
- decided not to wait for Norbert’s test b/c timeline too long
- Eric and Stefan measured required cable length after the meeting
- 100 cm cables will be long enough to instrument about half of the prototype
- decided to order 50 cables of those (available soon)
- 200 cm cables will be needed for the bottom half of the prototype
- decided to order 50 of those from the Taiwanese company (long lead time)
- additional discussion
- we have different lengths signal cables in sPHENIX: from preamps to interface boards; those are differential
- in sPHENIX those length differences will be moved to the coax pigtail cables
- propagation time etc will depend on signal shape: need input from Norbert
Simulation status and plans
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Derek: tile merging (see slides)
- white space not understood
- algorithm ready for review
David: MLP optimization (see slides)
- LD has nothing to tune
- Derek: test more kinematic points , but more than 20 GeV not necessary
- Derek: to do : manual comparison (will have time soon)
- looking at sum of energies in different detector
- Stefan: need to compare to what we get if we apply regular cuts (linear regression)