Calorimeter Geometry Review

June 17, 2003, 10:00 PDT, VRVS-CenA

Participants

Tracy (chair-under-duress), Joanne, Sasha, Eric, Berrie, Traudl, Leon, etc.

Introduction

This meeting was the second part of a general review of the implementation of the GLAST geometry, in preparation for Data Challenge I. We will review the current CAL geometry, and try to identify areas that need improvement.

Agenda

• How the geometry works (or doesn't) -- Joanne (pdf)
• Dimensions, materials, and all that -- Sasha (pdf)

Executive Summary

• Since the implementation of the DetModel geometry there have been significant changes to the Calorimeter geometry which should be incorporated into the model:
  • The CsI crystals are now wrapped instead of having the reflector be an integral part of the carbon fiber support structure
  • The "model" for the Carbon Fiber support structure needs updating to make it easier to compare with the engineering drawings
  • Need to modify the top frame shape to better reflect the true design
  • Need to include the dead material between the towers - impacts the leakage calculations
  • There is a completely new baseplate design which could affect backgrounds
• Update to the constants used in the Cal geometry:
  • Modify some values of existing constants to reflect changes
  • Renaming existing constants to better reflect usage
  • Creation of some new constants for changes to geometry
• These modifications will require Joanne to dedicate some weeks of time, will/should be a high priority to complete before the July Software Workshop. There will be some further fallout which will require some "tweaking:" the detector display (if not all info obtained from DetModel), fine tuning the energy algorithms (e.g. CalValsTool), etc.
• It was felt that, in general, the Cal software folks are "closer" to the actual device than the Tkr software folks. Hence it is probably not necessary to have a formal subsystem sign off on the Cal geometry as is being requested of the Tkr geometry.