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Analysis of Coincidence Time Differences in 52Cr Target Experiments - Meeting Summary

This document summarizes findings from the May 21, 2010 meeting regarding experiments with a 52Cr target, focusing on coincidence time differences and Chi-square cuts. Key issues discussed included sudden changes in hit patterns, adjustments in second discriminator thresholds, and the impact of these changes on data quality. The analysis highlighted the correlation between the Chi-square cut and signal/noise improvement in the Λ-binding region, along with future actions needed for data verification and analysis. Attention was drawn to identified anomalies and their implications for experimental outcomes.

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Analysis of Coincidence Time Differences in 52Cr Target Experiments - Meeting Summary

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  1. HES HKS meeting 21 May 2010 T.Gogami

  2. Content • Coincidence Time difference • EHODO17 • Chi square cut

  3. Coincidence Time(htimetar - etimetar) Run 76956 – 77124 for 52Cr target ( 1/3 of all runs ) ? coincidence time abs(htimetar – etimetar + 55)<1 coincidence time abs(htimetar – etimetar + 55 + 0.6)<1

  4. Coin timeRun num. 77032 - 77091 Something happened

  5. Check “Hall C Log” • RunID < 77065 • htimetar – etimetar +55.0 + 0.6 • RunID >=77065 • htimetar – etimetar +55.0

  6. EHODO 17 hitpattern 77068 77062 • EH hitpat. changed at Run 77063 • Signals which going to 2nddiscri. are small due to high rate. EH 2nddiscri. thereshold changed to -100 [mV] from -200 [mV] • After pushed the cable connected to F1 TDC , EH hitpat. became normal ! 77063

  7. Chi square cut CH2 , HKS track CH2 , HES track • Scan • htrkchi2 / htrkndf < X • etrkchi2 / etrkndf < 3 FIXED 52Cr , HKS track 52Cr , HES track FIXED

  8. S/N with different χ2 cut BETTER than without χ2 cut NReal CH2 NAcc. NAcc. definition not so good

  9. Event num. ratio with different χ2 cut ex.) X=3 • CH2 : 69 % • 52Cr : 25 %

  10. Missing Mass for 52Cr Λ binding region Λ binding region QF QF Acc. Background Acc. Background

  11. Summary and to do • Summary • Cointime cut • RunID < 77065 • htimetar – etimetar +55.0 + 0.6 • RunID>=77065 • htimetar – etimetar +55.0 • EHODO 17 • cable connection before F1 TDC • chi square cut • a lot of bad tracks for 52Cr • chi square cut  S/N improve in Λ-binding region • to do • check cointime • golden data to analyzer • matrix with GEANT4

  12. END

  13. 5/17/2010 2次会

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