LhARA radiobiology; meeting: 29May25; 14:00 BST

Present: HO, CD, KL, RR, JMcG, RG, RW, JP, EM, MH

Notes

1. Minutes and actions:
   • CH: Provide CAD drawings of the Beamline for the wiki
     • Done.

2. Field mapping, preparation of PMQs: HO/BS
   
   • Frames waiting for delivery on 11th June. May be able to nudge that sooner.
   • 3 PMQ magnets with Hywel and 4 already at SCAPA

3. Layout design update: RG, RW
   
   • Layout can be configured with an air gap or with a tube to the TP.
   • The cell carousel should be placed up against the beam window, so can add the flange on the back.
   • Lanex or RCF stacks can be placed in the beamline.
   • A feature is required for the RCF stack holder to confirm the orientation of the stack.
     • Could be done with a notch in the tube
     • Or a fiducial added to each stack by a laser, which would require sending the design away along with a carousel.
   • Fume Cupboard exhaust is "totally wrecked".
     • Plan B, if not fixed in time, is to mount the cells in the carousel in a different building and transport them the ~100m to the beamline in the carousel.

4. PMQ Positioning: CD, RG, JMcG
   
   • Josie found significant beam loss at the first quad.
   • For distance to the 1st quad >93mm, the best transmission to a final spot size of 1cm is ~5-6%:
     • source->Q1: 101mm
     • Q1->Q2: 89mm
     • Q2-> end: 1268mm
     • Total beamline length: 1518mm
   • Suggested that to increase the transmission, the 93mm could be reduced to 35mm, and may only be limited by the RCF stack size.
   • Calvin will investigate whether lower energies have better transmission.
   • A better understanding of the off-energy particles is also required, which requires a simulation of the scapa proton spectrum.
   • Ross to share the proton energy spectrum for simulation, and Robbie mentioned a new divergence model

5. Simulation update: AFR, CD
   
   • Ken has refined the source model to remove spare parameters and include the new model for electron temperature and a Strehl ratio (slides).
   • Plan to use Te and Kmax as effective parameters to recreate the energy spectra.
   • The MSci students will return to investigate further and investigate the use of the laser parameters and whether it can match the experimental data, which could be used to help simulations at other beamlines like ELI.
   • Hopefully able to use the Phase 1 run data for verification.

6. Bioprep: EM/MH
   
   • Saw no survival when the media was removed. By leaving 0.5mm of media, the cell survival increases.
   • Also, might have to do irradiations in triplicate instead of duplicate due to uncertainty on cell survival.

7. Discussion of Beamtime
   • 5 days straight might be too intensive for bio prep.
   • Ross to share the timetable on the wiki, with the hope that it is conservative with timings.
   • Decided it would be beneficial to get some cell samples prepared for the Phase 1 run for the practice.
     • If not done, it is still worth the bio prep team to visit before the Phase 2 run to check and walkthrough.
   • Studies to reproduce Josie's beam loss against distance to the 1st quad graphs are also suggested.

8. Discussion of New Meeting Time
   • Keep at 14:00 on Thursday as default, but before each meeting, check if 3pm would be a preferred time.

9. DoNM
   • 12Jun25 14:00 BST

10. AoB
    
    • Trouble with editing the wiki?

Summary of actions

• HO: Nudge delivery of PMQ frames
• RW/RG: Feature to be added to RCF stack holder or to the stack to determine orientation post irradiation.
• CD: Investigate lower energy transmission and incorporate simulation of SCAPA proton spectrum to investigate off-energy particles.
• RG/RW: To share proton spectrum, new divergence model and beamtime timetable for CD and the wiki
• Troubleshoot access to editing the wiki.

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