Today's Progress 24. June. 2006 (updated every moment)

Tune of T0-PA time walk by (K^-,X) with PA-PB-detected velocity (PB fixed) (1)

Method

Here, we study the run-by-run time walk of T0/PA with Kstop-charged-triggered event set, by

DeltaT(T0->PA) = Tpa - Tt0 - TOFkstop - TOFsec,

where TOFsec is caluculated from the 1/beta determined PA-PB TOF, TOFkstop is simulated value. In order to achieve better resolution of the distribution center, we fully impose KstopID > -1. (MeVee) condition. Note that we cannot determine the offset for all of the existing counters - we do need to select a counter to give a absolute reference. The PA R segment 4 is selected as the reference, and absolutely fixed. Then, segment-by-segment tune is performed for T0 row 2,3,4 with PA R-4, the PA L/R arms with T0 2-4 segment-by-segment. Finally, T0 1/5 is tuned with respect to PA R arm. Note that TOFsec is dependent on Tpa - but the dependence of TOFsec on Tpa is smaller than that of DeltaT, by factor 0.2. Thus, at the initial stage of the tunning, the possible error on TOFsec due to PA/PB time walk is consciously neglected.

Result

Run-by-run time walk of T0 2nd layer segemnts

Run-by-run time walk of PA Larm segments

Run-by-run time walk of PA Rarm segments

After T0/PA time offsets are tuned, PA arm-by-arm T0PA TOF resolution, which is defined as the Gaussian sigma to fit the distribution, is as below. Assuming the PA time walk obtained here, run-by-run PB time walk is studied nextly.

Run-by-run stability of T0-PA TOF resolutiuon, obtained from Kst-Charged triggered event set. PAPB 1/beta 1.0~1.5 are selected from "Kstop" events without any energy loss correction on flight time.

Arm-by-arm T0-PA time residual for run 135.