Choose timezone
Your profile timezone:
46th BLM Thresholds WG Meeting
→
Europe/Zurich
774/2-058 (CERN)
Minutes from the 46th BLM Threshold Working Group meeting – 11.10.16
Present: C. Bahamonde, J. M. Jowett, A. Lechner, A. Mereghetti, M. Schaumann, D. Wollmann, C. Xu.
IR7 threshold changes for the 2016 p-Pb run (A. Mereghetti)
Slide 6
Loss maps using the 2016 proton operation BLM thresholds: no dramatic changes other than some modifications coming from setting the energy to 6.5TeV instead of 6.37TeV and YETS2015 corrections. Hotspots don’t change.
Slide 7
RS10 BLMs require a change higher than 20% so the suggestion from Barbara of installing a new family could be interesting.
Corrections should follow the red curve (pattern from signals) instead of the complete flattening hinted by RS10.
Anton says if flattening is followed, this would lead to an opening in the longer running sums, so this is the best that can be done for the moment. Daniel agrees.
Alessio comments on the increase factors, respect to last week they went up a bit, from 4,4 to 5,4 in some running sums, due to the update in YETS because of the change in monitor factors.
Slide 9
Alessio feared that only with 6 families of collimators, it wouldn't be enough to converge in a solution so he assumed point 1.
Plot 1, TCPs follow the B2H case with protons, shows why it's not possible to use the TCPs. Some hopes lie on the secondary collimatorss and very last TCLAs, since they are not affected by the crosstalk from beam 1.
Plot 2 estimated limit power, 6 monitors that could be used, 3 TCLAs and 3 secondary collimators.
Daniel says the 30 kW are not going to be limiting because that would mean with the planned operation parameters all beam would be lost in 30 seconds, what would be a problem.
The proposal of playing with the MF is also quite flexible and should be considered. Alessio says that he would look into the possibility of getting trapped if using the MF play. Another possibility would be to create a family just with 2 skew collimators keeping the MF and injection values where they are.
Daniel asks if it would be limiting to go a factor 10 down in injection BLMs and Anton replies these 6 BLMs could be crosschecked by Chen's tool.
Anton would vouch to not go for secondary collimators, because they depend on the settings a lot, but Alessio says he can check this.
Daniel says it’s true going for them is not ideal even although settings won’t change, but like this it would also be possible to gain experience for future ion runs. Secondaries change only by half a sigma while TCLAs change from 11 to 14 sigma.
Slide 12
Extrapolated from 6.5Z TeV.
Slide 13
Daniel asks why stay conservative if a new quench level could be found out when quenching in this run, but Anton says the difference is still very low. Since this has always been the approach it shouldn’t be changed.
Alessio says using the updated thresholds the map changed quite a bit from past week, no update is required.
Slide 14
Same analysis was done with the rest of the beams and orientations and few BLMs are concerned, 20-40% changes at the maximum. Anton says according to Barbara it's not worth to change them.
Slide 15
Alessio says it would only be needed to touch the master tables of the monitor factors of BLMs that popped up at 6.5 Z TeV.
Daniel asks if we should go for two skew TCSGs and keep TCLAs back for IR7. Everyone agrees and reminds the same changes should be done in both beams because beams will be exchanged later on.
Thresholds will be kept for ions and protons because of the short duration of ion runs.
Michaela asks for the reference for this calculation. Alessio says for 6.5Z the 6.37Z TeV quench test was used, especially B2 because leakage was less and because protons have a much better cleaning.
Chen asks about checking the injection, he suggests a flat top correction as a back up solution if we actually happen to be limiting in injection BLMs. Daniel and Anton think this is unlikely.
Anton asks about plot 2 slide 10. Alessio says MF now is 0.4, if set to 0.29 for example, then it's equal to the readout in the quench test, therefore the limit it's not 30kW but rather 80kW. Alessio suggests to just go for the two skews and Chen will check for these new monitor factors. Same for the other sides. Daniel proposes to leave a bit of margin, like 20%.
Alessio asks John, about the intensity of the proton trains. 36 of proton bunches, 28 lead bunches. Since currently it's 96 it should be fine , plus the ion intensity is different.
Anton asks Alessio, if it would be possible to harmonize the BLM thresholds in the magnets applying maybe the same factor instead of different ones (slide ‘Adjust BLM Thresholds in IR6 DS II). Other side should also be checked.
Slide 6: to the question why is there a peak on the loss map at 11L5, Alessio says at the time there were no collisions. John says this could be the collimation, like Point2, and he also points out that for the optics planned to be used in this run the loss maps are not available yet and they could come in handy. This should be checked because it's explainable according to Daniel, since this is only in Beam 2 it might be a single jaw behavior so it shouldn't be applied to both beams.
Anton will summarize this in a couple of slides for MPP.
There are minutes attached to this event.
Show them.
