General EEEMCal Meeting Summary 3/18/22

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PARTICIPANTS: Sasha, Hamlet, Richard, Rosi, Vardan, Tanja, Douglas, Carlos, Hrachya


  • EEEMCAL: 3256 PWO crystals (including spares)
  • Action items:
  • mechanical includes design check and updates as needed and insert (or alternative) to reach the highest possible eta
  • prototype beam tests for SiPM readout
  • continue development of specifications
  • BEMCAL: 8800 SciGlass blocks (including spares)
  • Action items: studies to be done include optimization of length/depth and angle/granularity and further design details on readout adapting PANDA design


  • Studies are based on the ATHENA geometry, but general conclusions are the same
  • An important parameter is the ratio of radiation length vs. Moliere radius - shower elongated compared to transverse size and resolution impacted by longitudinal shower fluctuations
  • this ratio is largest for SciGl compared to PWO and W/ScFi, so SciGl is most sensitive to nonprojectivity
  • Consider a ~20% pi0 merging probability as adequate and anything better as excellent
  • PWO excellent over the entire EEEMCAL range
  • SciGl adequate for EEEMCAL momentum range (<18 GeV), but would benefit from projectivity - need to check in detail for barrel
  • For these studies used minimum energy cutoff of 100 MeV
  • Scaling to EEEMCAL in the ECCE geometry:
  • ATHENA/ECCE offset is a factor of 210/175=1.2 - shorter than in ATHENA on which studies above were based - therefore the momentum range will shrink by this factor (for the same efficiency, the corresponding pi0 momentum will be a factor of 1.2 smaller in ECCE compared to ATHENA).
  • In terms of values, for 90% eff it will be 30 (40) GeV for eta=-2 (-3). So, it considerably exceeds our requirements in this region (<18 GeV).
  • Note on projectivity for the barrel EMCAl based on SciGlass
  • Note the angles for the different rapidities
  • eta = -2 (15deg at IP)
  • eta = -3 (6 deg at IP)
  • If one considers a barrel of radius of R=80cm, then by scaling one may reach 5(?) Gev for eta=0 limit if nonprojective by no more than 10(?)deg
  • Note that if the tower size is comparable to the Moliere radius then may be able to build the detector with smaller tower size --> perhaps move to a transverse size of 2-3cm
  • Discussion about items to show for SciGlass in barrel
  • two main interests: 1) e/pi separation, 2) pi0 discrimination
  • in general homogeneous EMCal provide better e/pi sepration, but blocks needs to be long enough. Fig. 43 of the ECCE Calorimetry note illustrates the effect of limited module length, comparing points with curves (left plot). The biggest effect is in the BEMC. If one fixes the electron efficiency at 95%, the pion suppression factor is very low 10-30 over the entire momentum range. The performance may be considerably improved for longer modules.
  • For pi0 one might to an approximation use a simple scaling with the distance from the collision point to EMCal tower
  • Resolution may not be the only parameter to look for, but it needs additional justification/studies
  • Attenuation and projectivity for SciGlass - impact on nonlinearity and light collection


  • DESY prototype tests
  • preparations for shipping equipment to DESY ongoing at MIT
  • paperwork for ANL travel and beam test participation almost complete
  • JLAB prototype tests
  • planned for fall 2022 (Sept-Nov time frame - exact dates TBD soon)
  • procurement of SiPMs and preparations for SiPM arrays ongoing
  • Crytur-USA working on new prototype
  • Action item:
  • evaluate possibility to test one module of new Crytur-USA prototype in May-June time frame at JLab