Overview

• Meeting objective: define actions and needs for setting BLM thresholds for the next ion run (Nov)
• Expected schedule: 4 days of commissioning and 2 days of MD.
• Previous loss maps will be used as a reference for scaling.

Ion Run 5 Configuration - Roderik Bruce

• Optics and Setup:
• Smaller β* in IR8.
• Reverse polarity (RP) in IR5 triplet.
• Crossing angles remain unchanged.
• Luminosity: Expected to be similar, but levelling time for IR8 will be longer.
• 2025 ion cycle to remain same as 2024 with additional squeeze step
• Collimation performance :
• Simulations show losses consistent with 2024 configuration.
• Summary
• RP in IR5, non-RP in IR1
• Dispersion correction added in IR2 and IR8 (new bumps introduced).
• IR8 squeeze to 1 m with new corrections and Q-bump.

• Discussion:
  • Full collimation and background checks to be done with ALICE.
  • If issues arise, will revert stepwise during commissioning.
• Polarity differences between IR1 and IR5 should not significantly affect loss maps. Crossing angle remains the same.
• Dispersion useful for crystal optimization, particularly for ALICE (IR2/IR8) - now no dispersion in IR7 - may be blind on crystal optimsation - to be verified.
• Commissioning:

BLM Threshold Recap - Sara Morales Vigo

• Changes needed going from protons to ion, due to different losses in IR7 due to crystal collimation.
• Crystal collimation reduced DS leakage but increased local losses (TCTs, TCLDs).
• Thresholds initially defined via 15 kW quench test.
• Crystal collimation can see up to 30–50 kW losses (depending on channelling mode).
• IR7 Thresholds:
• 2023: 5 families for channelling, 2 for amorphous (no VR).
• 2024: similar families, updated corrections and lower leakage via TCLA (11σ → 8σ).
• 2025: proposal to keep same setup pending final loss maps - consider though TCSG.A6R7.B2
• DS Strategy:
• Keep 2015 Pb-based thresholds; scaling confirmed adequate.
• Review Q6 family (BLMs detect fragment leakage from IR7).
• Updated thresholds from FLUKA studies; increased MF for RS families.
• IR3:
• Dedicated Q6 family added in 2018, no additional changes
• Thresholds increased by 30% (2023) and x2 (2024) to avoid limitations.
• RF@12 MV de-bunched beam tests stopped BLM warnings seperately.
• TCT/TCLD:
• No major change; thresholds adjusted based on loss maps.
• Collision Losses:
• BFPP losses managed by orbit bumps (IR1/5 to cryostat, IR2 to TCLD, IR8 more distributed).
• Quadrupole downstream losses under review.
• 14R8 anomalies under investigation (not fully understood).

Discussion

• Loss Maps & Commissioning:
• Need loss maps (CH, AM, VR) before the technical stop to scale and verify thresholds.
• No major configuration changes expected elsewhere.
• Quench Tests:
• Future quench test may be shifted to next year (possibly during p–Pb run).
• No change in master thresholds anticipated; only MF may be tuned.
• 14R8 Losses
  • Cause of losses uncertain

• TCT.8 BLM Threshold Review
• 1m squeeze in IR8 results in tighter settings for TCT.8, probable increase in losses and so BLM thresholds could be reviewed.

Conclusions & Next Steps

• Maintain 2024 thresholds and configurations unless loss maps indicate a need for revision.
• Prepare updated loss maps for all modes (CH, AM, VR) and for injection.
• Plan for a follow-up meeting once loss maps are available to finalize MF and BLM thresholds.

• Keep monitoring IR8 losses; simulations don’t fully match data yet.
• Possible review of BLM thresholds for TCT.8