Modified the LYSO target design

[zwl0331]

I am updating ldmx-sw, here are the details.

What are the issues that this addresses?

This resolves #1370 and implements the new design for the LYSO target. It consiste of two layers. The first layer has 32 bar, while the second has 33 bars.

Check List

• I successfully compiled ldmx-sw with my developments
• I ran my developments and the following shows that they are successful.

[bryngemark]

Hi Sam,
if your PR is ready for review (necessary before it gets merged), you need to pick at least two reviewers who will take a look and approve when satisfied. @tvami, @tomeichlersmith or myself would all be qualified.

To help us understand how you know that your changes are good, please upload some plots in this discussion thread, explain what you ran to get them, and what they show. (This is the purpose of the second box, that you already checked when you made the PR. I unchecked it until you have shared some more material.)

[zwl0331]

I implemented the following geometry:

In Geant4 this looks like this:

• Side view:

• Front view:

[tomeichlersmith]

Thank you for the images! Those look great :)

I just want to confirm that this runs and the geometry doesn't have any sneaky issues (e.g. overlaps that are not visible because they are small but could cause issues during the simulation). Can you share a configuration you've used to confirm that this geometry successfully runs a simulation?

We can then run the same configuration with

# sim is the simulator configuration object already created
sim.validate_detector = True
sim.verbosity = 5

so that ldmx-sw takes extra time to make sure the geometry is valid.

[zwl0331]

I have talked to Dr. James Oyang, @joyang8caltech, and he agreed to run some simulations using this geometry. Dr. Oyang, I forked a version of ldmx-sw into my github account and made the geometry modifications. It is at https://github.com/zwl0331/ldmx-sw You can clone it to run simulations with it.

[tvami]

Sorry it took me some time to look at this (DR writing...), I made some suggestions / questions in below.

Generarly I'd really like to see some tests that use this geometry, furthermore I'd suggest to either copy or rename the whole directory to r2, i.e. ldmx-lyso-r2-v14-8gev the r was for the revision, so it was exactly meant for this purposes. If you chose to rename, please add the info in the README that v4.1.4 is the last one to have ldmx-lyso-r1-v14-8gev

[tvami]

Can you add a comment what this adds up to? Is it still 1.1 mm? If not what's the radiation length of the new thickness?

[zwl0331]

This adds up to 1.34 mm. I will add a comment in the file as well. @joyang8caltech may know the radiation length.

[bryngemark]

I have talked to Dr. James Oyang, @joyang8caltech, and he agreed to run some simulations using this geometry. Dr. Oyang, I forked a version of ldmx-sw into my github account and made the geometry modifications. It is at https://github.com/zwl0331/ldmx-sw You can clone it to run simulations with it.

How is this going? Please see the specific geometry validation instructions posted here by @tomeichlersmith.

I also wonder, @tomeichlersmith and @tvami, if we should have a validation workflow for geometry changes? (This is not the last time we'll make an update.) We do expect a whole lot of changes to distributions, so it's not clear what tests are meaningful, apart from that things run, and the overlap check tom mentioned.

[bryngemark]

By the way @zwl0331, @joyang8caltech, the plastic geometry doesn't look right. We expect to have 24 bars in each plastics array, so they are equal height but staggered in y.

[joyang8caltech]

We need to have thirty two 3mm height and 40mm long LYSO bars so that the active LYSO target will have the same coverage as tungsten target. On Dec 16, 2024, at 6:17 AM, bryngemark ***@***.***> wrote: By the way @zwl0331<https://github.com/zwl0331>, @joyang8caltech<https://github.com/joyang8caltech>, the plastic geometry doesn't look right. We expect to have 24 bars in each plastics array, so they are equal height but staggered in y. — Reply to this email directly, view it on GitHub<#1498 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/A24FEATKUB4RTRRVJDB5Q4T2F3OI5AVCNFSM6AAAAABSNDXYUKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDKNBVG42DOOJYGM>. You are receiving this because you were mentioned.Message ID: ***@***.***>

[tvami]

if we should have a validation workflow for geometry changes?

I agree we need this, but I think we should have this after the sensitive volumes are defined, then we can do a PN sample with LYSO in the CI

The validate_detector doesnt work, see #1533

So we need to do this semi-blind...

@zwl0331 can you please update the code with the comments from me and Tom?