Jul 2026-Sep 2026

Attendees: RL, MK, SS, AH, BZ, EM, NT, PB, SZ, (ÉM late), EC, AP, JI, SQD, CSW, IH, Ziyu, JY

Regrets: 

Announcements:

• Forward progress underway on G4CMP-655 (RL)
  • Feel free to make subtask if I have changes, etc.

Agenda:

• Ryan Linehan: G4CMP-662: Fixing Biases in the QP Diffusion Code (slides)
• Émile Michaud: Geant4 Beginner's Guide (pdf, google slides)
• AOB

Attendees: RL, CSW, RB, ZC, AP, NT, JL, BZ, MK, JB, IH, Jason Brodsky, JI, JY, JY, SZ, EM, WL, SS, DS, CL, RB

Regrets: 

Announcements:

• New folks: Abby Postlewaite (Postdoc at UW-Madison, spin qubits), Jason Brodsky (works with Yaniv at LLNL – Geant4 expert)
• G4CMP-662: Reducing the bias from QP WoS diffusion coupled with singular reflection probability at transparent boundaries
  • Teaser:
  • Ryan should update ticket with this!!!
• Documentation track-athon (doc-athon?) poll: 

  https://whenisgood.net/3b35c4d

  • Please fill out today – times are next week!!
• Progress on memory and CPU issues reported mid-August G4CMP-655 - Jira project doesn't exist or you don't have permission to view it.
  • BZ Solved TouchableHistory problem  G4CMP-665 - Jira project doesn't exist or you don't have permission to view it. – no longer have giant memory leak!
  • Memory leak is gone, but still working through CPU time (callgrind) debugger output

Agenda:

• Caitlyn Stone-Whitehead: Refining Phonon Reflection/Transmission Probabilities

  • See also: Rokhlin, S. I., T. K. Bolland, and Laszlo Adler. "Reflection and refraction of elastic waves on a plane interface between two generally anisotropic media." The Journal of the Acoustical Society of America 79.4 (1986): 906-918.

  • G4CMP501.pdf
• Upcoming feature releases:
  • Charge reflection G4CMP-515 - Jira project doesn't exist or you don't have permission to view it. : completed the additional sanity checked suggested previously, 0V and lattice-to-lattice surface, both behave as expected.  Ready to merge onto develop.
  • Bulk recombination G4CMP-517 - Jira project doesn't exist or you don't have permission to view it. : ready to merge now, but would like to add a toggle to disable the "in flight" recombination if desired.
  • Physics-based intervalley scattering G4CMP-404 - Jira project doesn't exist or you don't have permission to view it. : Think Emile considers it ready to go, but need to confirm in PR.
  • Memory and CPU issues G4CMP-655 - Jira project doesn't exist or you don't have permission to view it. : New ticket G4CMP-665 - Jira project doesn't exist or you don't have permission to view it. to fix just the memory leak and get it onto develop ASAP.
  • Charge transmission G4CMP-606 - Jira project doesn't exist or you don't have permission to view it. : still in progress from Selby, but moving forward rapidly.
• AOB

Recordings: video, audio, chat

Attendees: CSW, SQD, MK, SS, RL, JB, JY, JG, BZ, SZ, Kiichi, DS, EY, WL, JV, JI, JL, ÉM, AH, SH, ZG, TC, MM, EM, CL

Regrets: 

Announcements:

• Welcoming Zach Gillis, 1st year Stanford/SLAC students,
• Welcoming back John Vaccaro, Stanford/SLAC, rising senior UG
• Question on g4-v11.4.2: new ticket or one already exists?
  • Stefan: You can't – plan is to stick with 11.4.1 until 11.4.3 or 11.5.0 is out.
  • G4CMP-641 - Jira project doesn't exist or you don't have permission to view it. , already closed since change we had to apply got applied, but revealed a G4 missing feature which needs to be patched
• Documentation hackathon – will send out a whenisgood today to organize this
  • Ryan will coordinate with Birgit offline before sending email
• Put out V10-05-00 on Tuesday, announced on Slack
• Please join RISQ Slack! Ask Mike/Ryan if you are not on and want to be!

Agenda:

• Charge Reflection at Surfaces, Wade Lamberson (TAMU)
• Charge Recombination in Bulk, Michael Kelsey (TAMU)
• AOB

Recording:

• Video: video1324757988_0820BWTM.mp4
• Audio: audio1324757988_0820BWTM.m4a
• Chat: chat_0820BWTM.txt

Attendees: RL, SS, EK, PB, JY, BZ, ÉM, SZ, MK, JI, DS, JLG, EM, WL, GC, SQD, 

Regrets: 

Announcements:

• New ticket: QP boundary transmission probability: G4CMP-652
  • Should read absorber Eff in KaplanQP
  • surfaceType: seems like it's not used in G4CMP – this may be the way to do it rather than reinventing wheel
    • Read G4 chapter on optical processes
• A&M group will have a couple of talks on improvement to charge surface collisions: G4CMP-515/517
  • Will be ready in 2 weeks, potentially sooner
• Introducing new members:
  • Dylan Scully: UWaterloo – phonon modeling, completely new to G4CMP (yay!), working with Adrian Lupascu
  • Jamie Lee Gill: UW-Madison, met at RISQ – works broadly in QIS and is interested in G4CMP

Agenda:

• Elijah Kane (Caltech): Jonas' group

Attendees: RL, JI, CSW, SS

Regrets: Almost literally everbody (DPF (https://indico.fnal.gov/event/72820/) and SCDMS collab meetings this week...)

Announcements/Discussion:

• None of note from FNAL side
• CSW: working on isotropic/anisotropic parts of the phonon transmission/scattering
  • Able to reproduce results from SALER: phonon propagation through silica → silicon (and back) seems to be working
  • Will slot herself in for a talk when it's made it to a clean presentation point
  • Virtual beer/journal club for some topics?

Agenda:

• Had a pretty small meeting but talked a bit about some interesting reading in this paper: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.23.468
• AOB

Attendees: RL, MK, RB, DT, SS, RM, GC, WL, ÉM, JY, ZC, MJ, TC, PB, SZ, SQD, BZ, JB, SR, NT, JI, IH, CL, 

Regrets: 

Announcements:

• Reorganization of the Confluence Underway
  • List of institutions + "envoys"
  • Public vs. Non-public slide locations

Agenda:

• Decoding Detector Response: Advanced Phonon Modeling in SuperCDMS (PDF), Rik Bhattacharyya (TAMU) https://docs.google.com/presentation/d/18pIiSUp1pWb4lKTluDChHbrAYURGhYs1QKKcaSWx0yE/edit?slide=id.g3f7d5749c54_0_24#slide=id.g3f7d5749c54_0_24
• AOB