Shield Status

1
Shield Status Plans

• TM 2221 Mokhov, Rakhno, Striganov, Peterson
  Radiation Load to the SNAP CCD 09/15/03
• Progress in development of work plans for FY04
  FY05
• Physicists Engineers
• What we want to accomplish at the Collaboration
  Meeting

Tom Diehl 10/22/2003
2
Preliminary Results from MARS - Sources

• The Radiation Load comes from
• Trapped protons and electrons
• Primary protons, electrons, and heavy ions
• Solar Events

Creme96 Spenvis Proton spectrum matches
(within a factor of 2x) AMS data in higher
energy Range This is a very good start.
Cosmic Ray Sources
3
Shielding and Detector Model (1)

• The trick with MARS is to select the appropriate
  level of detail.
• Include the most important shielding components.
  Consideration is given to proximity to detector
  and components mass
• Put a lot of effort into detailing the detector.

4
Shielding and Detector Model (2)
5
Preliminary Results

• Results from Galactic (Primary) hadrons
• The shielding seems to be generating low energy
  neutrons. I dont yet know if it is making this
  component of the dose worse than not having a
  shield.

• The cold plate is the worst generator.

Neutrons from primary hadrons
6
Preliminary Results

• Results from Trapped radiation
• The total dose is higher. The shielding helps.
• Not so many neutrons are generated

• Solar Flares
• 4 rads from the worst day

Trapped hadron flux
7
Preliminary MARS Results

• Total Dose
• Suggests we may want to shield better when we are
  in the radiation belts.
• Effect on CCDs
• Im still trying to figure this part out

Predicted degradation over 4 yrs ().
8
Progress in Physics RD Plan

• For the SNAP RD plan
• I wrote a partial plan for the shielding
  simulations MARS and Geant
• I need to check with NVM on the MARS part of the
  plan. Hes been busy.
• I need to identify people resources for the GEANT
  part of the plan (to help Fritz D.)
• Id like to improve this before we go to LBL.

9
Progress in Engineering RD Plan

• For the SNAP RD plan
• Tom Nicol will lead the engineers
• Tom Page has already been working on this
• Lanfranco, Cease Olis have expressed strong
  interest.
• This is a good group. These are the guys I want.
• They are meeting this week to come up with
  something better than my first attempt.

10
Collaboration Meeting

• Whos going from the shield group? What are they
  going to do?
• Physicists Diehl (talk), Dejongh.
• Engineers Nicol, Lanfranco, Cease
• Tom N. has to meet and make friends/plans with
  the LBL guys
• Giobatta to get into FEA on the shield itself
• Cease (w/ Scarpine?) to look into the photon
  ray-tracing and reflections
• Go out Saturday, come back Tuesday red-eye or
  Wednesday morning. Attend the collaboration
  meeting and the first day of the internal review.

11
Summary

• The previous update to you guys was August 20.
• Since then
• TM 2221 by the MARS guys is a good first start
• Developing plans and schedules for simulations
  part and engineering part.
• Received a big boost in engineering resources. (I
  plan to defend it).
• Collaboration Meeting plans