Ad-hoc discussion on BLM thresholds for next Ion Run

Monday 15 Jan 2024, 09:30 → 10:30 Europe/Zurich

Anton Lechner (CERN), Belen Maria Salvachua Ferrando (CERN)

Scientific Secretary: Sara Morales Vigo

Notes by R.Bruce

Participants: R.Bruce, R.Cai, M.D'Andrea, A.Lechner, D.Mirarchi, S.Morales, S.Redaelli, B.Salvachua

Inputs to the discussion: 
    • What can be done in the ramp, e.g. flattening "v-shape" to avoid having bottlenecks at intermediate energies? Any particular bottlenecks that can be removed?
          
    • What can be done at flat top for short running sums - can we be more tolerant of 10 Hz losses, e.g. by increasing RS06? Can we increase the Q6 further? Any other bottlenecks?
          
    • How can we account for the different orientations of the crystal - if we're in volume reflection or amorphous, did we dump too early or not?

What we concluded:
        1. Typically dumped on Q6 or TCTs – check these ones first.
        2. In general, review the Q6 strategy. Unlikely to quench, always in the shadow of the collimators. Present thresholds assumes direct losses can hit the aperture
        3. Consider removing “V-shape” in the ramp at Q6 and TCTs
        4. Check with Fede/STI – do we have margins on the tungsten collimators (TCLAs in particular)?
        5. Put TCLDs in different family than TCLs?
        6. In reality, volume reflection was most critical for Q6 – reason why we were dumping too early. Should include VR – Marco indicated loss maps done in VR
        7. Include also transition region where we dumped the 10 Hz in the later part of the run (with auto-pilot). We have no dedicated loss maps in the transition region - is it an intermediate case between existing loss maps?
        8. Extend list of 2024 validation loss maps to VR and transition region
        9. With new Q6 strategy, possibly updated power limits for tungsten collimators, and the loss maps from 2023, should in principle have the main ingredients to calculate updated thresholds that increase tolerances for the losses that were limiting in 2023 (10 Hz, losses in the ramp)
        10. In addition, Volodymir doing FLUKA simulation of IR7 energy deposition for 10 Hz, maybe in VR? Confirm margin to quench for 10 Hz
        11. BLM threshold meeting to be organized later in the year