SNAP Shield Group Meeting May 28, 2003 Dejongh, Diehl, Fehers, Kerby, Page, Peterson Next Meeting ------------ June 11th, 2003 IB1 2nd floor West 10:00 to 12:00 Noon. This includes the Instrumentation Meeting with LBL at 11:00. The phone number for that is: 510-643-3819. 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. Tom succeeded in making patterned conical cuts through the Solidworks model and in integrating the material within the cut. The result is a table of theta, phi, and amount (kg) of material. He use a cone radius of 5 deg and a couple of cone spacings, 5 and 15 deg. There was substantial cone overlap, particularly at the poles. We agreed that, in principal, such overlap isn't a problem and that it can be reduced by using an appropriate number of cones at a given theta. The sphere was centered around an arbitrary point on the focal plane. Compute time is an issue. The 5 deg x 15 deg model took two hours for 266 cones. The other took nearly 24 hours for it has 2522 cones. The reason he uses cones is that's what's available in Solidworks. He understands that space-filling sections would be useful. It might help to remove the non-shielding material from the model would speed up the calculation. The Solidworks model has ~900 parts. He wants to check that the material is specified correctly. For instance, it seems that in the Solidworks model the satellite is ~3500 kg. We believe it is actually about half that mass. Jim had the idea of making a table and then rotating the model (or the cones) by half a cone radius and then comparing the material. This would help ensure we hadn't missed anything. We agreed a 10 deg x 10 deg parameterization centered around the center of the focal plane is where we want to start. We realize we have to demonstrate we can make good use of this information. In the future we will want to have radial cuts in the cone. A method was devised that might provide that information as well. It was noted that the conical shield section isn't mounted quite right in the Solidworks model. We would like to fix it and send the model back to LBL. Summary of Material in the Satellite - Tom Peterson --------------------------------------------------- Tom Pe. would like to make another iteration in the word document which summarizes the material important as shielding. Completing such a list might allow Tom Page to know which items in the Solidworks model are not important (see above - the issue is compute time) and will be helpful to Nikolai and Co. if we decide to model the satellite as solid pieces in Mars and GEANT. NOVICE - Fritz DeJongh ---------------------- He writes: "Here's a link to a program called "novice" that was used for shielding calculations for the "James Webb Space Telescope." It apparently can import CAD models and do traces through them, and lots of heavy-duty stuff. The cost is 50 to100 K$! Has anyone heard of it?" See http://see.msfc.nasa.gov/ire/model_novice.html The novice code uses Monte Carlo methods and/or approximate kernels to perform particle transport and shielding calculations. The model can be run interactively or in batch mode. This code is an industry code and is available to be purchased through the point of contact below. Primary Deuteron Spectrum in Near Earth Orbit - Diehl -------------------------------------------------------------- Tom has extended his program for generating cosmic ray backgrounds (see previous three minutes for discussion on protons and helium) to include Deuterons as measured by AMS. The reference is M. Aguilar et al., Phys. Reps. 366, 331-405 (2002), Table 4.12. Next is primary leptons from another AMS reference. Diehl's slides are in this folder. See file diehl_05_28_2003.ppt. SNAP Instrumentation Meeting Phone Conference --------------------------------------------- One finds the talks on the SNAP web page internal documents. We gave a very brief verbal report. John Marriner came over to IB for this, as well.