Aug 18, 2016 Calorimeter

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Meeting Time: 11:30 a.m.

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• JLab Phone: in CC F326 is 757-269-6460 (usual room)
• JLab Phone in CC L207 is 757-269-7084
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Agenda

1. BCAL Timing Calibration (Andrei): Media:Tcalib-meet-160818.pdf
   • Paul: do not use the BCAL in the RF determination to remove bias, although this probably will not affect things much.
   • Paul: DFOM cut may introduce a bias. The 0.5 pion cuts may be too tight; loosen them. Try DeltaT cut instead of DFOM with loose +/- 2ns cuts
   • Paul: Using Vertex is fine and for sure do not use t0.
   • Elton: slide 3 has path length times beta; should it not be divide by beta?
   • Paul: Simon has methods to correct for dE/dx in calorimeter and will send these to Andrei.
   • Andrei: it takes 5-6 iterations to converge so that the difference in variables is order 10^-3.
   • Andrei: function is not piecewise, just a simple sum of terms. X represents pulse peak after pedestal subtraction.
   • Andrei: no of neutrals is 4-5 times the no of charged events. Charged particles were used to start this procedure, due to historical reasons.
   • Question: what happens if the charged particles are removed from the procedure on slide 5?
   • Elton: would George's quadratic term remove some of the variation seen on slide 6?
   • Matt: decoupling theta and shower size from the procedure would be desired, if possible.
   • Elton: why is the resolution at theta=90deg not better (e.g. Hall B BCAL beam tests)? Andrei: t_res includes timing effects from whole system (BCAL, RF, tracks). Beam tests had e- going in at 90deg without TOF. t_res is not far from design specs on energy term; constant term is higher though. Due to SiPM noise?
   • Andrei: slide 12 key point: left plot has strong correlation => major contributor is cell size. Matt: islands seen in red plot although not as clearly as blue ones.
   • Andrei: lab coordinate system is used by new results, fADC ones, and George's.
   • Andrei: slide 15, top right plot shows valley between pions and protons, so PID is possible even at this level.
   • Sean: we would need to create a new table to accommodate the coefficients from Andrei's timing calibration.
2. Concerns, issues to be addressed:
   1. Matt: having different v_eff for up and downstream is a concern, conceptually, as this is a physical property of the fibres. Can we use different techniques for position calibration and timing calibration?
   2. Sean: run this procedure through MC. Andrei: David Lawrence's full pulse handling has been removed from the MC, a while back. Matt: but Geant handles some of this. Andrei: Geant uses COG method, and does not use the edges of the shower cone, as our MC stands.
   3. Matt: zoom into the plots on slides 13 and 14. Systematic shifts are visible.
   4. Elton: will this presentation be turned into a document? Zisis: yes.
3. Concerns send it later via email:
   1. Curtis: investigate base term in resolution being worse than expected.
   2. Curtis: can we explain the two effective speeds to an audience easily?
   3. Elton: for plots on slide 13 and 14 plot the difference vs position, e.g. pick the old z-coordinate and plot (Andrei - old) vs old and (George - old) vs old for both charged and neutrals.
   4. Sean: while the focus of this effort is on the precision time calibration using TDCs, if we are changing the parameterization of the effective velocities, is there a plan for how we would determine them for layer 4, which just has ADCs? This would primarily affect the clustering.
   5. Christina: slide 6 shows layer 2 only. What do the other layers look like?
   6. Christina: Can this effect be handled by two separate t-w functions instead of two effective velocities? Method works, but in an unphysical manner (same conceptual concern as Matt's above).

Minutes

Attendees: Elton, Simon, Paul (Jlab); Matt (IU); Will, Curtis (CMU); Sean (NWU), George, Christina (Athens); Andrei, Tegan, Zisis (UofR)