ad-hoc BLMTWG (IR6 Q4/Q5 protons)

Europe/Zurich

Daniele, Anton, Belen, Sara, Fabian, Kate

  • Simulations of standalone super-conducting magents 4.5K Q4/Q5 CERN-THESIS-2023-043
  • Response factors from simulations for primary impacts at the TCDQ (1-side collimator - 9m) and TCSP (2-jaws collimator - 1m).
  • Checked what would be the expected primary impacts at the present applied thresholds (MF=0.4).
  • Checked expected energy deposition peak at the Q4 and Q5 and compared with the limit of 30-40 mW/cm3.
  • This shows that a factor 2 could still be safe, but larger factor is discarded without further studies. 
  • File from A.Apollonio 2018 with quench levels - stored in the BLMTWG cernbox.

 

If/when implemented this, we need to check:

  • how to align it with the master thresholds and monitor factor used
  • what happends with B2 that has lower response
There are minutes attached to this event. Show them.
    • 10:45 11:05
      Q4/Q5 Fluka simulations 20m
      Speaker: Anton Lechner (CERN)
      • Higher leakage to IR6 from IR7 in B1H loss maps from 18cm beta star
      • Simulation of BLM responses in Q4 and Q5 from impacts on TCSP/TCDQ collimators, to see if there is risk of quenching the magnets
      • Belen says that in 2023 ion run there was also observed higher signals in IR6 with B2, at that moment the TCSP jaw was opened to alleviate the losses
        • A possible increase of up to a factor of 5 for RS09 was agreed
      • TCDQ only has one jaw (9 meters long), TCSP has two (only one meter down)
      • Some meters below a mask, TCDQM, then the first superconducting magnet Q4, some more meters downstream (about 20) the Q5
      • Impacts on TCDQ: 2e-12 Gy/p Q4, 1e-12 Gy/p Q5
      • Impacts on TCSP: 6e-12 Gy/p Q4 and Q5
        • Makes sense as TCSP is shorter, so less absorbing, higher BLM response expected downstream
      • MF = 0.4 for the BLMs at Q4, Q5
      • TCSP and TCDQ losses at Q4/Q5 dump threshold estimated (for applied thresholds)
      • Q4 has the mask, so power deposition per proton lost is lower than in Q5
      • Q5 has a peak of power deposition in beginning of magnet
      • Both magnets of the MQY type at 4.5K
        • Q5 gets to 3500A
        • Q4 gets between 2500 and 3000A
      • Maximum power deposition in Q4 and Q5 at which we are expected to dump calculated, higher for Q5 as different BLM response
        • Quench level depends on magnet current
        • There should be some margin, but there is still some uncertainty
        • Could allow for a factor of 2 probably, a factor 5 would be too much
        • From document from Andrea 
          • 37 mW/cm3 quench level for 3000A at 7 TeV, will have to check for 6.8 TeV
      • See how to apply this change -> so that master threshold is at quench level?
      • Anton shows Run 2 studies that show that the leakage to IR6 from IR7 seems to decrease with higher loss rates
      • Daniele asks why for B2H it is not expected to reach the thresholds at the same IR7 power loss even though there seems to be similar inefficiency during loss maps
        • Fabian shows that for the equivalent B2 BLM, the response during B2H loss map seems to be around 3 times lower
        • Belen and Anton remind that one should also consider that the responses in IR7 also vary for B1 and B2