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VPDMB purity check and vertex position check (Update on March 31)

Updated on Tue, 2015-04-07 13:20. Originally created by dongx on 2015-04-03 10:48.

Here I give a latest check on the VPDMB online vertex cut purity check as well as the vertex position (beam line) check.
Previous studies are linked here
https://drupal.star.bnl.gov/STAR/blog/dongx/run15-pp-200-gev-beam-position-check
https://drupal.star.bnl.gov/STAR/blog/dongx/run15-vpdmb-5-trigger-commission

Data used here were taken on day March 31, three runs from the beginning, the middel and the end of a typical store
16090044, 16090048, 16090053

Fast offline chain option:   VFPPVnoCTB replaced with VFMinuit for Vx,Vy check. No beam line used.

  16090044 16090048 16090053
Vz Correlation (TPC vs VPD)
Vz dist. after |Vz-Vz_Vpd|<6cm cut
  sigma = 7.42 +/- 0.07 cm sigma = 7.35 +/- 0.05 cm sigma = 7.36 +/- 0.06 cm
       
Vertex X, Y position in STAR global coordinates

Red - TPC center
Black - fit center to data
       
       


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