20200722-PREX2-Analysis

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Agenda

1. Chandan: GEM performance HAPLOG 4187
   • Siyu: we are working one 6 GEMs alignment. We are checking if every step makes sense, eg. unknown spots. Based on SBS cosmic test, we can achieve ~100 um precision for alighment.
   • Chandan: I have tried to alighment GEM with VDC tracks.
   • KK: what will be beam energy in the upcoming run period?
   • Dustin: we have uninstalled the lowest GEM below the detectors.
2. Tao: Beam correction (Lagrange-All results) HAPLOG 4186
   • surprised to see chi-square improved at pitt level compared to slug level plots
   • Why regression 5 bpm has a big chi-square?
     • KP: we don't trust 5 BPM regression. Regression can give minimum width but misleading central value. It can be wrong with limited BPM resolution.
     • PA: Correlated BPM electronic noise can be the problem in regression 5 BPM. Using all BPMs in regression and Lagrange multiplier will help.
   • David: why ditheirng vs Lagrange all has a larger error bar 3.5 ppb ? Is it the systematic error?
     • KP: dithering has limited BPMs resolution compared with Lagrange all.
     • KK: we can't tell systematic error based on this error bar.
   • David A: why in the first ~ 13 slugs, the differences between lagrange all and regression all shifted to one side and noisy?
     • TY: we haven't look at details in these slugs yet. It seems to be the lower current run period
     • CP: when do we start using bpm 11X as energy monitor? KP: slug3.
     • KP: Maybe it is beam tune. still not clear why it is correlated with beam current. Something we can look into it.
     • David: It maybe the dithering coefficients are wrong.

Present

Adam Z, Bob M, Caryn P, Devi A, Ezekiel W, Juan Carlos C, Robert R, Tao Y, Chandan G, Juliette M, Silviu CD, Weibin Z, Ciprian G, Paul K, Hanjie L, Kent P, Amali P, Ye T, Ryan R, Cameron C, Paul S, Sakib R, Sanghwa P, Yufan C , KK, Dustin M, Iris H, Brian Q, Guido U, Victoria O, Siyu J, David A