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["Brandenburg, Daniel" <brandenburg.89 AT osu.edu>]

Hi Leszek,

Yes I’m glad this came up. Have you updated the density already? It should be fixed asap and that way future studies will incorporate the change. So if not please submit a PR for that asap. Though the effect of reduced density should be somewhat trivial to calculate we want the correct numbers in the geometry. 

Best,

Daniel

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From: Leszek Kosarzewski <leszek.kosarzewski AT gmail.com>
Sent: Tuesday, June 3, 2025 3:03:07 PM
To: epic-backward-hcal-l AT lists.bnl.gov <epic-backward-hcal-l AT lists.bnl.gov>; Brandenburg, Daniel <brandenburg.89 AT osu.edu>; Lisa, Mike <lisa AT physics.osu.edu>; Aschenauer Elke-Caroline <elke AT bnl.gov>
Subject: Steel density confirmation for nHCal

 

Dear Colleagues We realized that the density of the steel which is defined in materials. xml is a bit too high (8. 3 g/cm^3) for a standard non-magnetic steel: https: //github. com/eic/epic/blob/dc18cc16566268b613553df110eef3d2820a82af/compact/materials. xml#L414-L419

Dear Colleagues

We realized that the density of the steel which is defined in materials.xml is a bit too high (8.3 g/cm^3) for a standard non-magnetic steel:

https://github.com/eic/epic/blob/dc18cc16566268b613553df110eef3d2820a82af/compact/materials.xml#L414-L419

  <material name="StainlessSteel">
    <D type="density" value="8.3" unit="g / cm3"/>
    <fraction n="0.74" ref="Fe"/>
    <fraction n="0.18" ref="Cr"/>
    <fraction n="0.08" ref="Ni"/>
  </material>

You can compare it to Steel235 used by LFHCAL:

https://github.com/eic/epic/blob/dc18cc16566268b613553df110eef3d2820a82af/compact/materials.xml#L66-L70

  <material name="Steel235">
    <D value="7.85" unit="g/cm3"/>
    <fraction n="0.998" ref="Fe"/>
    <fraction n=".002" ref="C"/>
  </material>

I think we really need to double check the material composition and density. The density will affect the simulations, so it needs to be updated to correct values.

On a separate note, I added a switch to make all layers sensitive and made a pull request to merge it into main. This is needed for the sampling fraction benchmark code in preparation now.

Best regards, Leszek