SNAP Shield Group Meeting May 14, 2003 Dejongh, Diehl, Kerby, Nicol, Page Next Meeting ------------ May 28th, 2003 IB1 2nd floor West 10:00 or 10:30 to 12:00 Noon. This includes the Instrumentation Meeting with LBL at 11:00. The phone number for that is: 510-643-3819. I will let you know the meeting start time in a week. It depends on how much progress we have and on whether Nikolai and Co. can attend. Manipulating the SolidWorks Model - Tom Page -------------------------------------------- The problem of how to use SolidWorks to make a table useful for shielding simulation seems to be divided into two parts: 1) making a solid cut through the satellite using an appropriate geometry, 2) determining what the material is within a cut. We talked about how different shielding simulation approaches use potentially different levels of detail in the bill of materials. A Simple Attenuation Integral might use integral of material along a cosmic ray flight path. A calculation like Mars or Geant that produced and tracks secondaries and does nuclear interactions needs more detail. Tom has started working with making sections in a spherical geometry through the satellite model. At first he wants to provide a table of the total amount of material in spherical sections centered around a given point in the focal plane. The table would contain the material as a function of, for instance, theta-phi, and be useful for "quick-and-dirty" attenuation calculation Fritz has been advocating. Perhaps Tom Pa. could extend that using a combination of spherical sections and radial shells later on. Primary Proton and Helium Spectrum in Near Earth Orbit - Diehl -------------------------------------------------------------- Tom has extended his program for generating cosmic ray backgrounds (see previous two minutes for discussoin on protons) to include Helium as measured by AMS. The reference is M. Aguilar et al., Phys. Reps. 366, 331-405 (2002), Table 4.9. Next is primary leptons from the same reference. The Helium is apparently 90% He3 and 10% alphas, same ref. SNAP Instrumentation Meeting Phone Conference --------------------------------------------- One finds the talks on the SNAP web page internal documents. There were several presentations and less-formal reports. Henrik Von der Lippe wanted to know (from us) what the most relevant primary background source were for the CRIC. He may want to do radiation hardness tests. This electronics reads out the CCD's and sits on the back of the cold plate. It is not shielded in all directions. The kind of specification for radiation tolerance that he mentioned was 10kRad. He said it was possible to redesign so that it was radhard to 100MRad. He didn't say that's something he wanted to do. Afterwards Natalie Roe indicated a correction to above: "Just one clarification. The CRIC chip should be rad-hard to well beyond 10 kRad, probably to more than 100 kRad. We will have to do some tests to find out. The requirement was set at 10 kRad assuming that the back of the focal plane will experience lower dose than other areas, but that remains to be confirmed by your studies." We said we had begun work on the simulations that we have been talking about but didn't give a detailed report to them.