SNAP Shield Group Meeting April 23, 2003
             Dejongh, Diehl, Fehers, Kerby, Nicol, Page, Peterson, 


 Next Meeting
 ------------
 May 7th, 2003 IB1 2nd floor West 9:30-11:00 AM. 
 Tom P. has reserved this meeting room for the rest of the year.

 Overview by Tom Diehl
 ---------------------
 There were several new people at this meeting.  HTD presented an overview
 of the SNAP experiment components in which we are involved. This talk 
 was based on the shielding slides shown at the SNAP Collaboration
 meeting last month.
  The presentation relied on input from Tom Peterson and Fritz Dejongh
 for clarity and further detailed description.
 
 Report from Tom Peterson
 ------------------------
 Tom described several details he discovered on the "Mass and Power
 Spreadsheet" by David Pankow and dated 01/16/03. This is a link 
 that hangs off http://snap.lbl.gov/ following "Public Documents". 
 In particular the conical shield is massed-out at 24.8 kg. We believe 
 this corresponds to 1 cm of aluminum. There is a 25% "reserve" held
 for this part, commensurate with its early design stage.
 He also pointed us to Pankow's "Optical Telescope Thermal Concept"
 spreadsheet, dated January 2002 and available on the same page.
   We discussed some aspects of the understanding of the level of detail 
 known about components relevant to the shield.  And also some of thr
 conceptual detail.  For instance, why are the connections between the cold 
 plate and passive radiator now thought to be carbon fiber. 
   Tom P. has a book "Satellite Thermal Control Handbook" by Gillmore.
   Tom P. promises to update the March 26th description of the major
 mechanical components for the shielding model-builders with the new info
 learned from Robin L. on April 9th.

 Primary Proton Energy Spectrum from Tom Diehl
 ---------------------------------------------
 HTD read the AMS publication by Alcaraz et al., PLB 490, 27 (2000).
 It's titled "Cosmic Protons". AMS flew a short duration mission on the
 space shuttle in 1998. They measured the flux of protons at altitude of
 350-390 km as a function of the protons kinetic energy.  The results 
 are in Table 3 of that note.  
   HTD converted that into a fortran program that randomly generates
 a list of protons and their kinetic energy according to the distribution
 in the table. See diehl_04_23_2003.ppt for details of that procedure.
   More details and improvement about this to come from HTD and Fritz D. 
 in the next meeting.