BCAL Readout Segmentation Task group Meeting: Oct. 24, 2011

Meeting Info

Time:

• 1:30 JLab
• 11:30 Regina

Location:

• CC F326

Vid-con:

• ESNet 8542553
• EVO

• Phone connection:
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Agenda

Review action items from previous meeting

1. MIA

New Agenda items

1. Neutron/photon discrimination (Beni)
2. BCAL energy/time Resolution Comparison to 2006 beam test (David L.)
   • GlueX-doc-1854
3. BCAL Reconstructed Time Resolution (Paul M.)
4. Discussion on argument sharpening (All)

Minutes

Participants

David L., Paul M., Zisis P, George L., Curtis M., Matt S., Beni Z., Eugene C (partial)

Neutron/photon discrimination

Beni showed some plots from simulated data indicating the discriminating power of the BCAL between neutrons and photons. The plots were uploaded recently and missing some labels:

• Red = neutron
• Black = photon
• x-axis:
  • bins 1-4 represent the number of neighboring readout cells that fired
  • bin 5 represents events where only the 4th cell (outermost) fired
  • bin 6 represents events when two non-adjacent cells fired

(A page describing the plots has since been put up)

The plots are normalized to indicate neutron and photon probabilities for each topology. These could be used to form likelihoods of a shower being due to photon and not a neutron and vice versa.

Beni will add labels to the plots and generate some for particles at different angles.

BCAL energy/time Resolution Comparison to 2006 beam test

Dave showed some plots showing he is able to match the 2006 beam test results in both energy and time difference resolution using the special simulation tool he has developed.

It was suggested that dark hits be turned back on to see how that would affect the energy resolution.

The work done has been summarized in a brief GlueX note.

BCAL Reconstructed Time Resolution

Paul showed some plots indicating the differences in timing resolution for various angles using parameters he obtained from David. The values were fit as a function of angle and then used to smear the "reconstructed" pion resolutions for b₁π events. Plots showing the Δbeta; vs. momentum of π⁺ candidates was then shown. The separation of the protons and pions was evident in plots made for the 1234 and the 334 schemes, but it was difficult to quantify by eye.

Paul will continue working on this by looking at a π(1600) channel which will have larger proton momentum and should make the separation more difficult. This might make a better discriminator between the 1234 and 334 schemes.

Discussion on argument sharpening

We discussed briefly how to proceed on firming up the arguments for the change request. 
Zisis noted that Andrei (out sick today) was expected to have more to show on the neutron/photon separation 
study he has been working on next week.

It was agreed that at next week's meeting we should bring together the best plots we have to date to make the argument for the change request. We would then discuss how best to present the information.

Action Items

1. Look at π(1600) events with higher proton mass to see if better proton/pion separation exists for the 1234 than 334 scheme. (Paul)
2. Add more labels and more angles to plots showing neutron/photon discriminating power (Beni)
3. Resolve issues with extracting proton timing resolutions from existing MC (David)
4. Write ITYS section of minutes (George)