Difference between revisions of "Sep 29, 2008 Calorimetry"
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Revision as of 13:57, 29 September 2008
NEW TIME Time: 11:15 ET.
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Items for followup from Sep 2 calibration meeting
- Each subsystem must complete blanks in the Specification Table.
Items for followup from Sep 15 meeting
- George: report on trip to Edmonton
- Decision on Bcal sampling fraction needed by Sep. - Initial work by Stamatis was reported
- Resolution studies (Blake)
- Up-to-date geometry ONGOING.
- Decreased threshold for FM pmts. ONGOING
- Position resolution - understand dependence on granularity.
- Different segmentation for the outer section. - LOWER PRIORITY
- Study impact of inactive material at the end of Bcal on acceptance.
- Add F100 rad hard glass to simulation. - New graduate student has been assigned this project.
Documents to Review
- From Will Brooks: http://www.jlab.org/Hall-D/software/wiki/images/0/0c/Geometry_effect_timing.pdf
- Update on VLPCs (Werner) 
- Results on study of increased sampling in BCAL
- Systematics in Bcal timing (Will)
- Update on VLPCs (Werner)
- Decision on cell for SiPM arrays. The proposal is to use the A20HD Getter#1 devices in the array builds.
- Trip to Edmonton
- Roadmap to decision on Bcal readout e-mail
Attending: JLab: Elton, Beni, Elke; Athens: Christina; UofR: Zisis, George, Andrei, Stamatis; Santa Maria: Will, Sergei; FIU: Werner; IU: Matt, Mihajlo, Claire, Ryan
- Calibration (Christine)
- Constructing box to shield laser from RF noise to check stability of laser
- Looking to purchase more LEDs. The LED they are using does not presently give sufficent light.
- All groups are encouraged to fill in the Table of Specifications.
- Announcements (Elton and Elke)
- The latest news from DOE is that the 12 GeV project will not be considered a 'new start' under a continous resolution. This could allow placing orders for construction early in the fiscal year. However, budgets are still constrained by the 2008 ped funding profile.
- Increased sampling fraction (Zisis)
- Simulations are continuing. For thin lead sheets the energy resolution blows up.
- Hybrid solution results in non-uniformities and is discouraged as a general rule. Also complicates calibration. At the moment the simulation program does not lend itself directly to this option (Matt).
- Bcal timing and geometrical effects (Will)
- Study implications of timing resolution in a toy model, Look at position dependent changes in mean time as a function of position. Assumes low TDC thresholds.
- For charged particles and showers, RMS ~ 240/sqrt(12) = 80 ps. This dispersion migh in principle lend itself to software corrections for accurate modeling.
- For neutrons, RMS ~ 70 ps, intrinsic due to the unknown neutron interaction position. Distinguishing photons from neutrons is important especially for nuclear targets.