Aug 25, 2016 Calorimeter

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Meeting Time: 12:15 p.m.

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Participant Direct Lines

• JLab Phone: in CC F326 is 757-269-6460 (usual room)
• JLab Phone in CC L207 is 757-269-7084
• Phone in the Regina Video-conference Suite is 306-585-4204
• Athens Phone: in Christina's office is 011-30-210-727-6947

Action Items

• Produce documentation for implementation of timing algorithms and constants (Andrei)

References

1. FCAL HDFCAL log book
2. BCAL HDBCAL log book
3. BCAL Action Items and Working Tasks

Tentative Agenda

1. Announcements
2. Action Items
3. Preparation for REST production
4. FCAL update
5. BCAL update
   1. BCAL non-linear energy corrections (Will M.)
   2. High energy shower merging (Will M.)
6. Calibrations
7. Reconstruction and Simulation
8. Any other business

Minutes

Attendees:Elton, Jon, Mark, Adesh (JLab); Ahmed, Zisis, Colleen (UofR); Will, Curtis (CMU); Sean (NW); Matt (IU); George (Athens).

1. Announcements
   1. Zisis: UofR has been supporting UConn to characterize the diamond radiators at the Canadian light source. Tegan and Andrei are helping now. The lab has provided great support. Future runs would benefit from adding a 2nd stage preparation of the beam to streamline measurements.
   2. Elton: The Compton Calorimeter CompCal is in being installed behind the Fcal. The support is located between back of the Fcal dark room and the first row of racks. The CompCal will be an array of Pb glass (~5x5) on a platform on one side of the beam to test feasibility of measuring the Compton signal coming through the beam hole. The plan is to install and connect the detector to electronics for the fall run.
2. Action Items
3. Preparation for fall run
   1. Fcal and Bcal will turn on after f250 electronics is tested and loaded with latest firmware
   2. Zisis: Assume Bcal will run at 1.4 V overbuys and T=5 deg C, as we did in the spring.
   3. Elton: The LED monitoring program by Ahmed should be readied for the run. Ahmed: LED pulsing system was checked for the spring run and found about 5% channels misbehaving. Most problems were for up/down channels during the low bias settings. This is likely an issue with the monitoring system or software, since at high bias the response was as expected. Ahmed is preparing a plugin to use the monitoring system to check the system response.
4. FCAL update
5. BCAL update
   1. Michel Electrons (Zisis for Colleen)
      • Colleen is finalizing a report on the calibration
      • It appears that the procedure will allow provide a calibration test point at low energy
      • Still need to estimate the accuracy of measurements.
   2. Error matrices (Mark)
      • Developing a brute force method to determine the covariance error matrix for neutral showers
      • Use MC single particle gun with single photons to generate variances and covariances in 5 parameters (E, r, phi, z, t)
      • Idea is to parameterize the distributions, so may need perhaps 60 parameters.
      • Prepare a report when work has matured. Goal was to complete the first iteration by Wed for the launch, but it may not get finished in time.
      • This will require changes to the code, which will need re-coding and testing.
      • Matt: Once completed, the procedure could be repeated for the Fcal, perhaps with a different coordinate system.
   3. BCAL non-linear energy corrections (Will M.)
      • Shower-level corrections vs E up to 2 GeV in process
      • Should be ready by next Wed for launch.
      • Matt: What happens to parameterization outside fitted range? It appears to flatten at high energy, but what is the behavior at lower energy?
      • Deviations from linearity at low energy (presumably) are due to thresholds and at high energy due to saturation of the flash.
      • Mark: J/Psi events show about a 10% lower energy in the Bcal compared to tracking.
      • Will: Is the the tracking accurate? It gives the correct J/Psi mass.
      • Elton: How/where are the corrections implemented? Will: New tables will need to be added to ccdb. The correction is made on the cluster energy to generate the shower objects. Sean and Will can coordinate offline to generate the necessary ccdb tables.
   4. High energy shower merging (Will M.)
      • Jane's analysis of exclusive pi0s does not find events at very high t and there was a concern that the shower reconstruction could be inefficient.
      • Investigated the reconstruction of 6 GeV pi0 in MC. Approximately 50% of the two pi0 clusters merge into one.
      • Finds that clusters are reconstructed with a separation in Delta Phi ~ 10 deg and Delta Theta ~ 2-3 deg.
      • Investigate options for distinguishing clusters with smaller separations. Using the event display, it appears that the clusterizer could be modified to find showers with Delta phi down to about 5 deg.
      • The clustering algorithm appears appropriate at this stage. At 50% efficiency, one should still see some events at high t.
      • Matt: Need to check that these efficiencies do not affect any publications that are in process. (They should not affect asymmetries)
      • Will: Eta is easier on the reconstruction; the pi0 is the hardest case.
6. Calibrations
   • George: Readying plugin veff for the next launch. Will update document documenting the latest work on veff.
7. Reconstruction and Simulation
8. Any other business