Injection beam losses at the collimators in IR7

• Simple calibration of TCP B1 and monitor downstream that does not saturate shows that dump (and saturation) starts at 0.7e9 protons.
• Can the losses be reduced?
  • Comparison of losses depending on bunches per injection
  • Max BLM signal along the year analyzed for BLMs with highest signals in B1 and B2
  • B1 systematically higher losses that do not correlate with intensity, lower losses at the end of the year even though similar intensities
  • Horizontal/skew collimators similar levels for B1 but different for B2 
    • B1 has higher contribution from horizontal losses than B2
    • Can be presented by Sara Morales in future meetings
  • Chiara says you also keep horizontal losses higher than skew in B2, opposed in B1, B1 more sensitive to steering, etc
  • Chiara asks when momentum drift was corrected, first time, Yann says early June.
  • Belen tries similar calibration to double check numbers from NXCALS instead of PM, reaches similar numbers.
  • B1 has larger tails in BLM signal for TCP skew collimator 
    • Tails coming mainly from horizontal and skew collimator for B1
    • B1 and B2 see similar vertical losses
    • Daniele considers that for B2 mostly vertical losses and in B1 a mixture... mostly horizontal losses
      • Chiara says B1 very sensitive to the horizontal steering, aware that problems in horizontal losses problematic, B2 is more steady
      • Chiara says B1 has always been like that, do not really know why, will keep investigating, have not been able to identify the source yet
  • BLM signal depending on bpi trains
    • Not so large tails for the 164 bpi
    • For 128 bpi, still some events with high signals
    • Chiara says maybe it is from some flatness in one line and not the other, Jorg says it might be oversampling the bad cases, 128 bpi are used for steering, Belen says could also point out to problem of extraction of the beam
    • Belen says she could also analyze the events from last year
    • Yann says MKI form was adjusted during last YETS, so bunches should follow each other well, then Chiara says that it has to be steering
    • Yann says he can check the extraction pattern, Chiara says differences with last year and this year
  • Max signal as number of bunches
  • Max signal as a function of injected intensity
    • Very large spread, expected as growing but not the case
  • Max signal as a function of the TDIS BLM signal, in case TDIS does not catch something that goes to IP7
    • No real correlation
    • CHiara would check with the vertical, Belen said that she can add it, Chiara would expect to see more correlation here
  • Correlation with SPS scraping
    • Increase of SPS scraping for H plane during the year, but not real correlation with losses
    • Jorg says still probabilty to dump higher with lower SPS scraping
    • Chiara saw fluctuations even inside the same fill
    • Anton asks about the % of the scraping, Jorg says BCT change from before and after, reliable, vertically ok with 1%
  • Correlation with energy matching
    • ONly impact from SPS-PS field correction, and during period with smaller losses, this was corrected
    • Correlation with primary collimators 
• Can the BLM signal be reduced?
  • Only possibility now for YETS, displace BLM to catch less showers
    • With a factor 2 reduction of primaries should be sufficient, at the same level as other BLMs limiting
    • Need FLUKA estimates of the optimal new position
    • Not to displace the BLM, but add a new BLM at the new position, duyring commissioning not interlocked, comparison of response factors, and if response factors teh ones expected, change of database settings -> Safer option
    • Chiara asks if move interlock, the other kept for checking, but not for interlock
    • Jorg says interesting option, as you also keep old signal
    • Daniel says least invasive solution
    • Chiara says you make system less sensitive, Anton says less losses but still high signal
    • Belen says you actually put it in an optimal position for the expected thresholds, aligned with the allowed power loss
      • This solution can be implemented already during the YETS
      • At the moment, thresholds on short RS at a much lower level than it should be because of this signal
    • Jorg says that double BLM proposal we lose nothing, you still have both BLMs for analytics
    • INterlock power loss will be adjusted accordingly
  • Blindable BLMs in IP7
    • As blinding configuratin deployed in all BLMs, possibility to allow 2 BLMs in B1 to inhibit the interlock during injection -> Many settings to be discussed before it is delivered to MP
    • Need to assess impact for combined fast failure scenarios
    • Blinding applied to all BLMs marked as maskable in LSA database -> would need to add an extra flag
    • Blinding time can be defined per crate
    • There is a way to avoid this, to add the blinding flad, but it is a lot of changes -> Not a good time to do this change now
    • Not an option for the shutdown
    • Can this still be done for 2025 -> Daniel says system not designed for this, would need to be done in a formal way, need to study first the specific needs
      • Anton says in case this is considered for HL, would be good to have experience for Run 3, Daniel says it could be done in an MD, and arrive to proper specification for this
      • Belen says we would need to find a solution for all fast loss cases, not only injection losses, as it will limit also
      • Same dynamic range for Run 4, only thing one could do is less sensitive positions or less sensitive detectors
  • Use of LIC detectors
    • Interlock during injection or fast losses on the LIC (less sensitive)
    • Would need to assess their stability first -> Replace SEMs in IR7 by LICs to gather this data
    • Forst analysis shows linearity bewteen IC and LIC BLM signals
    • Things to be understood like jump in the signal for the LIC 
    • Christos says they also want to build different prototypes on LICs, with different ceramics
    • Stefano says there is not much use for the SEMs anymore, he thinks they can be taken out
    • Belen remembers Jan being against it 
    • Daniel says if it is agreed here, to go to the MPP with this proposal and LMC 
    • Daniel will speak to Jan
• Anton says should add an MD to study the blindable time option for IP7
  • Belen says this has been studied a bit with the IQC data, losses in the order of ms
  • Yann says we could commission the blinding at the restart in points 2 and 8
  • Chiara says we should test the blindable option in IP7
  • Chiara would also like to have the LICs installed this year to start crosschecking the measurements,then we scale, see if we need more and plan for the future
  • Anton says we will not have 280bpi injections with the current filling scheme next year
  • Jorg thinks that at the end of the commissioning period, there will be set up of 1.8e11 injections, so will have enough intensity for this test
  • Stefano says he prefers to test as much as possible to be ready for the future
  • To be discussed if this is done as part of commissioning or as an MD
• Belen says that an option for the future would be a combined IC-LIC interlock
  • Christos says this should be specified and requested formally
  • There are some LIC BLMs already installed close to primary collimators, to be analysed further
• Removal of SEM and installation of LICs should be discussed in the MPP and LMC
  • Christos says SEM were never part of the protection system, so should go only for information
• Yann and Sara should agree on the message to be presented at the JAP workshop concerning the use of blindable BLM system

Removal of BLM in ALFA stations 7R1

• Removal of ALFA stations In A7R1 and B7R1 for sector 1-2
  • Preference of removal of BLMs associated to the to be removed stations
  • Both BLMs not connected anymore
• BLMs to be kept at the locations where the devices are kept too