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EPIC Far-Forward Weekly Meeting

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Description

Wiki: https://wiki.bnl.gov/EPIC/index.php?title=FarForward

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https://bnl.zoomgov.com/j/1602996456?pwd=NHlISDV4bWpDTlZVZjFWNzdkMEtBZz09

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Meeting topics:

ZDC reconstruction
 
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Attendees: Ralf Seidl, Tonko Ljubicic, Alex Jentsch, Prithwish Tribedy, Janusz Chwastowski, Sebouh Paul, Dominique Marchand, Yuji Goto, Wlodek Guryn, Zvi Citron, Grigory Nigmatkulov, Michael Murray, Shibata, jestradav

 

General Updates:

  • New EICROC firmware up and running on BNL test stands - goal is to reproduce some results from IJCLab and then shift toward setting up a dummy testbeam assembly with a GEM telescope from another BNL group.
    • Goal will be to figure out inclusion of an external trigger signal so readout can be triggered by telescope.
  • RBv1 setup testing is in-progress (power board was received last week, needs inductors to be soldered in-place). Testing in-progress, report by the end of the month.
  • Awaiting EICROC1 testboard schematic from OMEGA so BNL EE can work on v0 AC-LGAD (Roman pots) PCB design. 

 

ZDC reconstruction efforts in East Asia - Ralf Seidl 

  • Focus on baseline geometry, but also some work on upgrade geometries with WSi imaging + HCAL, heavy focus on Lambda reconstruction, which is among the most challenging things to do. --> goal to reproduce the UCR study, and then see how upgrades could improve on this.
    • Possibility of AC-LGAD layer in the ZDC to provide timing for some additional PID -- radiation damage a problem? Power/cooling? 
  • X-bias in slide on position and angular resolutions from Chia-yu Hsieh could be from the staggering of the SiPM on tiles hexes, and the beam is focused right down a particular pencil line - future simulations will be with a more realistic angular distribution.
  • Sebouh: Are we still using hexes, or switch to square cells in the SiPM-on-tile? --> something to follow-up on.
  • Work on WSi system for photon reconstruction is promising, especially when using a ML method (1D CNN) - prior to this, biases seen in position reconstruction along path of angle, but study needs to be repeated with a real angular distribution, as these biases are hard to judge with single angles.
    • Very early work on WSi + SiPM-on-tile for neutron reconstruction currently underway.

 

ZDC reconstruction - clustering in the SiPM-on-Tile sub-detector - Sebouh Paul

  • For Lambda reconstruction, all of the lambda currently come from the IP, but can decay anywhere along the beamline (so the secondary vertex is not a priori known).
  • Issue found is from cluster merging, which is a challenge for Lambda and Sigma decay. 
    • Part of the solution is to switch from hexagonal sub-cells to square cells, which allows for the ZDC to be designed in quadrants without deadspace.
      • Hexagons give smaller cells, but the dead space recovery with the squares could make a difference in the merging.
      • Squares perform a bit worse for angular resolutions for both photons and neutrons, but moreso for photons. Photons still perform ~5-10x better than neutrons, and beam effects are not included here (beam effects will set the lower limit of achievable angular resolution).
  • With the current results it is very hard to see if we achieve any real benefit from the potential change. --> would like to see follow-up studies.

 

General comments on ZDC studies:

  • We need to use realistic angular distributions (no more pencil beams) and add beam effects (afterburner). We really need to look at the resolutions using realistic conditions to ensure our algorithms are tuned to something resembling reality.
  • if there is a mechanical change to the ZDC layout, it needs to be discussed properly, and documented - the preTDR still shows hexagonal cells, and if that is going to change, it needs to be discussed broadly, justified, etc.
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