From PrimExWiki

Tuesday, April 25, 2006
2:00 pm
CEBAF Center, Room A110

Present: Eugene, Dustin( chair), Mark, Aram, Dave, Ilya, Mike, Eric, Kelli (on phone)

Contents 1 Topics and Plots 2 Latch word bit assignments 3 Timing 4 Tdiff Spectra 5 Missing bit9 TDCs 6 Studies to do

Topics and Plots

Dustin lead us through his web page

Latch word bit assignments

trigger	bit
MOR	1
HyCal Total Sum	2
MOR T2	3
TAC	4
Clock (10kHz)	5
_NOT_WIRED_	6
PS	7
LMS	8
HyCal single	9
MOR X HyCal	10, 12
HyCal cosmic	11

Production trigger was MOR X HYCAL, for runs less than 4932 it was bit 12, for runs greater than or equal to run 4932 it was bit 10.

For production runs the following bits were on: MOR X Hycal, Clock, MOR, PS(?)

Latch word bits also went to TDC's

Timing

• Gate timing made by MOR
  • MOR a narrow pulse inside wider Hycal pulse
  • Leading edge of MOR 40 ns after that of Hycal
  • Sum of widths of Hycal and MOR looks like 70 ns based on width of timing shoulder from trigphoton(?)
• Gate timing
  • ADC's were set up to have signal 20 ns into gate
  • ADC gate width was 250 ns
• Pulse widths (not known)
  • Decay time of fast component of PbWO_4 is 15 ns
  • Decay time of slow is 100ns (E.Auffray et al. NIM A 486 (2002) 22-34)
  • Relative light output of fast to slow unknown
• MOR
  • MOR is a simple OR of the first 11 t-counters
  • indivudual t-counter pulses were 15 ns

Tdiff Spectra

• Best trigphoton candidate gives coincidence peak (2 ns sigma) on top of large shoulders
• The width of shoulder correlated to sum of coincidence gate widths
• Sloped shoulders may indicate hycal ADC signal being cut into (due to improper gate timing, ...?)
• trigphotons in shoulder give no elasticity peak (maybe even an elasticity dip?)
• trigphotons in far bkgd (either side of shoulders) give a small elasticity bump

Missing bit9 TDCs

• Some coincidenceBit-latched events have no bit 9 TDC ?
  • Using default cuts for filling trigphoton bank ==> 15 - 20% of events have no valid bit9 trigphoton
  • Using no cuts for filling trigphotons: Still ~3.5% events with no bit9 TDC
• Also noted during meeting discussion that these same events also lack a coincidenceBit TDC ?
• All of these events with missing TDC info give normal tagm photon multiplicity
• ~Half of these events have cluster pair with mass>85 MeV

Studies to do

1. absolute efficiency of tagger
2. find runs with trigger = hycal only (maybe runs 3836 - 3839 could be useful)
3. analysis of synch events
4. trigphoton tdiff shoulder investigation
   1. examine tdiff spectra for each Tcounter some results
   2. examine shoulder shape when have no hits in any other Tcounter (and/or adjacent Tcounter)
   3. analyze runs with hycal single trigger...see if shoulders are missing
   4. examine total Hycal energy vs trigphoton tdiff some results view2
   5. examine pi0_elasticity vs trigphoton tdiff some results view2
5. implications of tdiff shoulder on experiment yield timing accidental background subtraction
6. consistency between trigger bits latched and trigger bits with TDC some results
7. investigation of events with missing hycal total sum trigger TDC (bit9)
   1. examine time of these events during run (are they evenly dispersed?) some results
   2. examine possibility of using htrigt stripsum TDC to recover events with no bit9 TDC