Tracker Geometry Review

June 11, 2003, 9:30 PDT, VRVS-CenA

Participants

Leon (chair-by-default), Joanne, Richard D., Tracy, Rich Bielawski, other interested parties (Traudl, Tsunefumi, Xin, Johann with dead audio... did I miss anyone?)

Introduction

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

Agenda

• How the geometry works (or doesn't) -- Joanne (ppt, pdf)
• Dimensions, materials, and all that -- Leon (ppt, pdf)
• "Fundamental Constants" -- need to:
  • Remove obsolete items
  • Verify all

Discussion

• Richard suggested using propagated muons to map out the geometry, and compare to expected values. Traudl later reminded us about the Geantino.  This seems like a good idea, but it needs some thought as to how to actually do it.
• There was a discussion about how to close the circle on the geometry. Leon has found errors in the "spreadsheet," which is what he gets when he asks for dimensions. Rich will try to track down the real source of the dimensions, and help us clear up the final details of the dimensions, and, just as important, the materials, especially for the passive tracker. The idea is ultimately have the subsystem check off on our geometry... the input numbers and/or the actual model, as expressed in the event display and the propagator.

Executive summary

• The active material in good shape; a few small bugs need to be addressed, and the composites (0.1 X0) should be recalculated with the latest info.
• The passive material needs some work, especially in evaluating the remaining items not modeled.
• We need a better connection to the source of the geometry. Rich will be working on this.
• It would be good to devise a (possibly) formal mechanism for having the sub-system sign off on the geometry. The work is in making the information mutually accessible. Maybe Rich can contribute to this effort.