Analysis Lessons Learned (d2n)

What follows is a (partial) listing of analysis lessons learned from Transversity, which may be a useful guide for d2n. Much of this is culled from Transversity analysis meeting presentations, accessible through the Transversity ELOG. I've given the student's name and the date of the relevant presentation, in italics, for each point. The Hall A Analysis Meeting is also a useful resource.

Beam Characteristics

• Calibrate phase difference between raster currents, BPM positions. (Vince, 2009.01.29)
• Transversity took an ARC measurement on Nov. 17. Do we have a d2n ARC measurement? (Vince, 2009.01.29)
• Raster x/y cables found to have been swapped (Jin at Analysis Meeting)

Target

• Extended target correction to account for <math>x_{tg} \neq 0</math> (Jin at Analysis Meeting)
  • THaExtTargCor class in analyzer

Optics

• Optics are calibrated with low-momentum data. Can we trust this calibration in a high-momentum regime? (Xin, 2009.03.06)

LHRS

General LHRS

• VDC T0 is calibration on which all others rest (Chiranjib, 2009.03.06)

S1, S2m

• Check ADC pedestal stability over time (Chiranjib, 2009.03.06)

Gas Cerenkov

• Check stability of SPEs over run period (Chiranjib, 2009.03.06)

BigBite

General BigBite

• New BigBite class for Transversity experiment: THaBigBiteE06010 (Jin, 2009.03.04)

BigBite Shower/Preshower

• Shower sum #15 never reaches T1 trigger (was this fixed during d2n?) (Jin, 2009.03.04)
  • Can tell from lack of self-timing edge
• We want BB timing to be precise enough to identify beam bunches (Jin, 2009.04.09)
• Timing calibration done bar-by-bar (in comparison with neighbors) (Jin, 2009.04.09)
• Check ADC pedestal stability over time (Chiranjib, 2009.03.06)

BigBite MWDC

• MWDC sensitive to timewalk. T1, T6 times are very different. (Xin, 2009.03.06)

BigBite Tracking

• Don't use scintillators; about 10% of Transversity events fail to fire the scintillators (Jin, 2009.03.04)
• An error in trigger formation time leads to an error in electron drift time, which leads to an error in computed drift distance (Jin, 2009.03.04)
• Tracking inefficiencies (esp. from timing) may disproportionately affect some particle types (e.g. pions) (Jin, 2009.03.04)

Triggers

• Since T3 arrives at the trigger supervisor before T5, it "steals" T5's timing. (Xin, 2009.03.06)
  • Can be corrected as a deadtime effect.
• Trigger timing can be checked via scintillator TOF (Jin, 2009.03.04)

Raw Asymmetries

• Basic cuts: (Jin, 2009.01.29)
  • beam trip
  • trigger type
  • vertex
  • quick PID
• Corrections to pairs (Jin, 2009.01.29)
  • angular reconstruction
  • polarization (target, beam)
  • dead-time