Monday, 25 August 2014Philip Symes Using PMT Gain Averaging as an Improved Method for Measuring Drift Points Philip Symes, University of Sussex MINOS “Week In The Woods” Ely, MN June 2005 LI Calibration Progress

25 August, 2014LI Improvements by Philip Symes 1 The Proposal PMT gain averaging From options presented at last meeting, we decided to concentrate on PMT gain method. Can use this method without any changes to online data taking Main advantages are to decreases database load and remove vulnerability to h/w changes, etc * Uncertainty on gain measurement 5.1% from 1k pulses Option: Online factor Offline factor h/w robust new code? Dead time stat. prec’n Std. LI11NoNo, but...0.1%1% gain, pmt10.008YesSome0.1%0.45%

25 August, 2014LI Improvements by Philip Symes 2 PMT Response over Time Must be sure that all strip-ends move together… So used CalDet LI data over 30 hour period to get necessary (2-3%) response change

25 August, 2014LI Improvements by Philip Symes 3 Linear Relationship between Stripend Drift & Stripend Gain The CalDet run drift changes agree with the gain changes, as we would expect. The gradient of the line is 1.072(79).

25 August, 2014LI Improvements by Philip Symes 4 Linear Relationship between Stripend Drift & PMT Gain The agreement between PMT gain change and stripend drift is also good: 1.046(72). Using PMT gain averaging is a viable alternative to standard stripend drift LI

25 August, 2014LI Improvements by Philip Symes 5 Drift with Gain Correction The PMT gain method is taking out the systematic changes leaving only statistical scatter Uncorrected Corrected

25 August, 2014LI Improvements by Philip Symes 6 Drift point dependence on nominal gain A plot of variation of the stripend’s drift compared to the PMT’s drift against nominal gain This is a VERY SMALL 2 nd order correction (~10 -4 ) Effect looks more marked at FarDet (better statistics) After Before

25 August, 2014LI Improvements by Philip Symes 7 Summary Of Proposal Keep online procedure the same for time being  (can go back to standard LI if problems found later) Use average PMT gain changes from gain point anchors to calculate drift in offline Method solves PULSERDRIFT DB table size problem: reduces to 0.8% of current size New method could also reduce the amount of LI drift point data that needs to be taken (less deadtime)