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[Leszek Kosarzewski <leszek.kosarzewski AT gmail.com>]

Hi All

I did a bit of digging and I'm pretty sure this is supposed to be the SAE 304 stainless steel with a price of  $4,400 to $6,600 per metric ton. This is supposed to be the cheapest non-magnetic steel. The material composition matches, but the density is 7.9-8 g/cm^3 instead of 8.3 g/cm^3. To me this clearly needs to be changed. Here are the affected detectors or structures:

https://github.com/search?q=repo%3Aeic%2Fepic%20StainlessSteel&type=code

I created an issue and fixed it in a dedicated branch here:

https://github.com/eic/epic/issues/884

We just need to wait for the approval.

Best regards, Leszek

śr., 4 cze 2025 o 12:03 Leszek Kosarzewski <leszek.kosarzewski AT gmail.com> napisał(a):

Hi Daniel

I don't think I can update just the density. It's more about which element composition we need. I'm pretty sure the StainlessSteel as defined is used by other detectors or support structures, so we can't update just that. This one has a high nickel content so the density may be correct. I can bring it up during calorimetry meeting to make sure, which composition is needed.

Once we get that information, I'll update it. For now, please have a look at my presentation.

Best regards, Leszek

śr., 4 cze 2025 o 10:22 Brandenburg, Daniel <brandenburg.89 AT osu.edu> napisał(a):

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

---

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