BCAL Readout Segmentation Task group Meeting: Oct. 10, 2011

Meeting Info

Time:

• 1:30 JLab
• 11:30 Regina

Location:

• CC F326-327

Vid-con:

• ESNet 8542553

Agenda

Review action items from previous meeting

1. Review existing documents on leakage and methods of resolution extraction to try and identify source of discrepancy between those and the current simulation study. (Zisis, David)
   • See David's slides
2. Verify that the missing energy from gustep/DESTEP is due to particles leaving the mother volume (David)
   • See David's slides
3. Clarify the total gain of the preamp board and whether or not it is included in the existing simulation (David)
   • Appears to be off by factor of 67/2 / 20 = 1.67 where:
     • Carl/Yi setup used gain of 67
     • Fernandos initial stage pre-amp has factor of 2
     • Total difference used previously was factor of 20 (should have been 67/2)

New Agenda items

1. BCAL energy Resolution (David L.)
2. Discussion on argument sharpening (All)

Minutes

Participants

David L., Elton, S., Pual M., Curtis M., Matt S., Eugene C., Beni Z.

BCAL energy Resolution

David showed some slides related to the BCAL energy resolution.

Slides 2 and 3:

Showed that the energy missing from DESTEP was leaving the mother volume.

Slide 4,5, and 6:

This showed how the variance calculation reported last week was incorrect. The original calculation was systematically high. Corrected values were summarized on slides 5 and 6. These were smaller (~2.0%-2.5% compared to ~4% for floor term previously reported). A comparison to numbers pulled from Stamatis' thesis Considerable discussion was had on the plots on slide 6, in particular the error bars. Some suggestions were:

• Run MINOS to get a better estimate of the errors of the fit parameters
• Fit σ² instead of just σ. Specifically, fit b2 rather than b since it may be better behaved.
  • (n.b. it is not clear if this avoids the issue of non-continuous first derivative since b² would need to be constrained to be positive to avoid imaginary values of b)

Other suggestions:

• Make missing BCAL energy plot for 90^o
• Apply a different threshold for the energy resolution than for the TDC

Discussion on argument sharpening

We had a discussion on what could be done over the next two weeks to propagate the existing timing resolution results to physics quantities. The discussion brainstormed ideas about where the timing resolution would have the greatest impact on a physics result. Some ideas were:

• PID. Specifically, proton/π separation due to time-of-flight
• Background cluster rejection
• Angular resolution of showers
• π^o mass width (Matt expressed some skepticism)
• pythia, b₁π

David and Paul agreed to meet later in the day to discuss details on what would be done. Here is the plan:

Paul:

The PID Paul reported at the collaboration meeting last week will be exteneded:

1. Turn off input timing resolution in mcsmear for the BCAL
2. Apply gaussian smearing of reconstructed BCAL clusters such that the resolution is 20% better than the current sim-recon result.
3. Examine improvement in particle ID in b1pi events. This will be done using timing information only, and for speed will use a delta-beta vs. p cut for PID rather than calculating the FOM.

David:

1. Re-run simulation with reduced gain factor
2. Apply lower threshold for energy measurement (relative to TDC) and re-calculate energy resolution
3. Determine timing resolution for protons and pions and communicate them to Paul

Action Items

1. Decide on best approach to incorporate current 20% resolution result in PID study (Paul and David)
2. Implement lower threshold for ADC than TDC when looking at energy resolution (David)