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A (very) preliminary result on timing

A (very) preliminary result on timing. DN & GS VRVS Meeting, 20 Jan 2004. Data analysis and sample. PRELIMINARY TASK : JUST T L -T R (  intrinsic resolution) Runs 6854 6857 (29 Nov. 2003) Live time  2h ,  25000 g collected (E>35 MeV in phase with S1&RF)

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A (very) preliminary result on timing

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  1. A (very) preliminary result on timing DN & GS VRVS Meeting, 20 Jan 2004 A (very) preliminaryanalysis ...

  2. Data analysis and sample • PRELIMINARY TASK: JUST TL-TR( intrinsic resolution) • Runs 68546857 (29 Nov. 2003) • Live time  2h,  25000gcollected (E>35 MeV in phase with S1&RF) • FSH52 almost completely open (DAC=350) • Trigger based on • S1*Q(LXe)*Q(NaI) • Collimator size: • LXe:9.5 cm • NaI:11 cm • High PMT gain(5106) • Good beam stability A (very) preliminaryanalysis ...

  3. Beam current monitor ~20 sbeam drop Troubles in scaler decoding as the on-line program fails to clear the scaler module in about 50% of cases A (very) preliminaryanalysis ...

  4. Hardware checks • Made use of all TDC channels (FTDC+CTDC+VTDC) although  50%of back PMT see< 5 pe • Cross-talks are largely suppressed at discri level (thanks to 10ns delay cables) but stillarising in VME TDC’s A (very) preliminaryanalysis ...

  5. Hardware checks (2) • Camac TDC’s look free from cross-talks, but poorer quality than FastBus L3 L8 A (very) preliminaryanalysis ...

  6. Hardware checks (3) CTDC distribution still larger after time-walk corrections (TAC , cables, ?)  needs to be investigated T3 T8 A (very) preliminaryanalysis ...

  7. The algorithm • TDC correction for time-walk (no position correction) • TL, TR by weighted average of Ti • <T> = (TL-TR)/2 i=r.m.s. of Ti cut on Qi> 5 pe A (very) preliminaryanalysis ...

  8. The result • Applied cuts: • Dr < 1cm(DT40ps) • 52<S1TDC<53 ns, 70<RFTDC<76 ns • Qsum>30000 ( E>50 MeV) • only 1000 events retained •  = 86 ps A (very) preliminaryanalysis ...

  9. Outlook • Need to investigate hardware problems (for present and future analyses) • Use of full analysis tools to obtain the overall timing resolution • Timing reference counter • Position reconstruction • DT vs E • Increase the statistics A (very) preliminaryanalysis ...

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