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https://ijclab.zoom.us/j/94064879903?pwd=UTFjbFlBZFhZOHlYYUVzWndpMGNIZz09
Meeting ID: 940 6487 9903
Passcode: 645647
Joint calorimetry weekly meeting (minutes from May 12, 2022)
The meeting included 3 presentations and associated discussions:
Motivation for a backward HCAL
Brian discussed arguments in favor of adding a backward HCAL to the reference design. Fast simulations based on DELPHES, PYTHIA8 and the ATHENA design were presented. Some initial conclusions:
The number of jets in the backward endcap is very low, but not negligible. For example, the photoproduction jet yield in the backward endcap is about 3% of the total yield.
JES and JER is improved by not using energy from neutral hadron objects (i.e. no HCAL), but creates a small neutral fragmentation bias.
Having an HCAL would permit quantifying this bias in a data-driven way and allow separate unfolding of jets with and without neutral hadrons.
Studies should now be performed using full simulations
Need to identify whether there are physics observables for which such a bias would have an impact
Discussion items:
(Friederike): one should consider the effects of gaps between the ECAL and HCAL, and also between the barrel & backward ECALs (if an HCAL is added)
(Friederike): requests to see the energy distribution of events in the backward HCAL in order to evaluate the quality of reconstruction that one may get
(Carlos): one should prioritize the search for physics channels that may be affected by the neutral fragmentation bias to see if an HCAL is needed. Brian points out that an HCAL may be useful for future studies that we are not considering at present and we should not close the possibility of an HCAL upgrade in the future.
(Elke): an HCAL upgrade is a possibility, but needs to be thought out from the start.
FEMC design (ECCE)
Nicolas presents the forward ECAL design proposed by ECCE:
Review of design parameters
Construction considerations
Cost (note: sci-plate costs expected to increase by ~2 due to unavailability of UNIPLAST)
Geant4 implementation and performance results: fulfills requirements of YR
Discussion items:
(Oleg) Clarification requested on how the ECAL connects to HCAL (answer: only with 2-4 mm steel plates).
(Oleg) Question about the laser etching technique
(Oleg) Requests more details on the geometry of the groves in order to estimate the cost of fabrication
(Sasha) Question about the energy range where pi0 photons can be properly separated. YR requires up to 50 GeV. Friederike answers that AI/ML algorithms are being tested to evaluate how high in energy we can do that (results will be reported at a future meeting)
(Elke) Points out that readout/electronics must be in the front of the detector for maintenance. Oleg also adds that SiPM will die very soon if put at the back as in the current design. Friederike thinks this change would not be a problem and will work on its mechanical implementation.
Additional questions were submitted in writing by Oleg through the mailing list, and Friederike is working on them.
pECal design (ATHENA)
Oleg reviews the ATHENA pECal design:
Integration volumes and costs
Review of WScFi technologies (eRD106 R&D plan)
Post-proposal optimization ongoing (segmentation, readout channels, insert around the beam pipe)
Technology meets the YR requirements
Discussion items:
(Friederike) Asks about the packing density of fibers and W powder. Oleg replies 10.5 g/cm3 for one that was tested, but depends on the type of powder you use. They will push for high density modules and probably be able to reach ~11 g/cm3.
(Friederike) Asks about geometry implementation in simulations to try to run it in Fun4All for a better comparison of performances. Oleg says that the most detailed implementation is in a standalone Geant4 (not in DD4HEP), but can be shared.
(Friederike) Asks about the reference of the glue, which could also be used in the ECCE design. Oleg will provide. Answer given in the chat by Sean Stoll: DP460.
(Sasha) Asks about the constant term (in sPHENIX it’s 3%). Oleg argues that 2% can be achieved (with improved quality of production, improved light collection and readout).