ACD Geometry Review
August 29, 2003
Attendees: Joanne Bogart, Toby Burnett, Jim Chiang, Richard Dubois, Heather Kelly, Matt Langston, Steve Ritz, Leon Rochester
Joanne provided a nice overview of the XML files and the general format of the constructs used for the ACD subsystem.
Joanne went over the current situation with the top curved tiles. She suggested that this could be improved by providing a vertical piece to cover the gap to more closely mimic the real design. There is a small area left exposed that would otherwise be covered. Richard suggested that we should be able to see if this gap is a problem by looking at the results of the latest 50 M run of background events.
We went over some comparisons of the mass in the model versus the actual mass spreadsheet provided by Ken Segal (GSFC). There was only one area for concern..probably due to Heather's careless addition.. in the side support structure. Heather will go back and check the numbers. All other areas were quite close.
Heather showed some pictures from the GUI using the new geometry. Currently the bottom ACD tiles overlap the top layer of CsI by ~2.6 mm. Steve explained that there is a requirement that the ACD tile overlap the CsI by some amount - however in the current design, the ACD tiles are shown to be a little bit above the top most CsI layer. It would be good to understand what is different in the model to cause the descrepancy. While we were holding the review, Dave Thompson sent around an email stating that the bottom ACD tiles have been shortened by 2 mm. Steve has an e-mail out to Ken Segal asking if this change was made before or after we received the SFX file describing the current ACD geometry.
Currently the ribbons are not sensitive volumes. It was decided to keep them insensitve for DC1 since AcdRecon has no mechanism to deal with the ribbons yet. Leon asked if we should remove the gaps for DC1 if the ribbons are not sensitive. This would seem to be a change that would not be allowed without good reason.
Heather mentioned other additions that could be made to the geometry: BEA, mass of cables, electronics.. Steve stated that it was not necessary to make these changes for DC1 - new additions would be made afterwards (Feb, 2004).
We discussed the thermal blanket/micrometerorite shield. Currently it is modeled as a single layer of magic material created according to the material specifications from a couple years ago. We discussed whether it was necessary to model the blanket more realistically as multiple layers - Dave Thompson had voiced his concerns that the blanket be modeled as multiple layers as it is in reality. It was decided that it is not necessary to do more than model the blanket as a single layer representing the total mass that particles would travel through.
Curved Tiles:
Richard to check the results of the 50M run with Bill to see if the gap left by
leaving out an additional vertical piece for the "curved" tiles
actually lets in a sizable amount of events. If necessary, Joanne will
make the change.
Mass Comparison:
Heather will go back over the side support structure mass.
Overlap of bottom ACD tile and top CsI layer:
Steve has a message out to Ken Segal asking if the 2 mm change in the bottom
ACD tiles is reflected in the SFX file we received on June 24th.
Distance between TKR wall and ACD subsystem (support structure):
Heather will check the numbers in the simulation with Ken and other in
system engineering to see if we are close.
Thermal Blanket:
Heather will find out what the current material composition is and will update
the material definition in use for Gleam accordingly.
Steve will talk to Dave Thompson about his concerns for modeling the blanket
realistically
Differences between new geometry and what is in "old" geometry:
Joanne will go back and check the numbers in the XML files
Useful ACD contacts:
Ken Segal
Mike Amato - system engineer
Richard Belowski
H. Kelly Last Modified: 2003-09-01 16:17:56 -0700