Telecon 20171212

Attending: Tom, Joy, Brian, Shaul, Karl, Qi, Toki, Jeff, Julian, Al, Jacques

Notes by : Karl

• No telecon next week
• Preparations for TeamX (JPL + UMN, led by Brian/Amy)
• Cosmic Rays (Jeff Filippini) B-mode from Space slides
• GRASP (Brad)
• Focal plane model, V3.0 (.pdf) (Young)

No telecon next week (TeamX meeting)

Preparations for TeamX (JPL + UMN, led by Brian/Amy)

• Brian making a list of files TeamX needs.
  • CodeV files. .seq files.
    • prep a 1.6 m and 1.2 m versions. UMN
    • 1.4 m with coma-correction and without. UMN
  • Kevin's current thermal model
  • Will get files/numbers from Roger. In email to Shaul: 0.8 uW on 100 mK, 1.8 uW on 350 mK. for TDM.
    • Shaul will ensure Roger has a wire count for FDM.
  • Cryogenics, ADR cooling power 10 uW. Kevin made a model that works for this.
  • Roger estimated FP mass, for 12-15k detectors estimate 7-8 kg.
    • in EPIC-IM a 1.5 m focal plane was 26 kg.
    • Core had similar focal plane size with waveguides and was 8 kg.

Cosmic Rays (Jeff Filippini) B-mode from Space slides

• first 2-3 slides are intro to problem. Rest are data from SPIDER
• Antarctic balloons good approximation of space at L2
• impact rate set by area, deposition energy set by thickness.
• Planck issue was wafer hits. long time constant (seconds) and high rate (few Hz)
• new space mission, wafers hit at 100 Hz. need short time constants. need bolometers unresponsive to cosmic ray hits on wafers.
  • should be able to absorb ballistic phonons and cool to thermal if wafer is coated in a superconductor (or normal metal).
  • then heatsink wafer well.
• if crosstalk of cosmic ray hits is nonlinear. Could be issues. increases the effective rate.
• consider hits to readout electronics as well. LC resonators could shift. SQUIDs respond. etc.
• Shaul: anyone planning to test this? like the phonon down-conversion?
  • Jeff yes, in progess. and Berkeley is also testing this month.
• SPIDER data. low coincidence rate, so no long distance propogation across wafer.
  • in lab tests see ~ 8 ms time constants. See saturated TES at high energies.
  • saw 'step' glitches. example of a weird thing. steps of 1 flux quantum. Large cosmic ray causes SQUID to lose lock on rising edge. Specific to TDM. Can be avoided in design.
    • Think about what readout does when large energy depositions.
• Jeff: No evidence for bolometer response to cosmic rays hitting wafer. Good sign, likely to avoid Planck's problem.
• Shaul: what are 1st priorities to look for in EBEX data?
  • Jeff: Coincidence is good.
• Shaul: Why does SPIDER see no long glitches?
  • Jeff: Better heat sinking. easier at 300 mK.
• Shaul: 100 mK measurements would be nice. Really show the problem or not.
  • Jeff: 100 mK is planned at JPL.

GRASP (Brad)

• Running, but Brad can't attend so topic delayed to next telecon.

Focal plane model, V3.0 (Young)

• Focal plane with pixels and hexagonal wafers is laid out.
• New sensitivity is 0.62 uK arcmin.
• Version posted on wiki.
• Toki: are all arrays < 150 mm wafer? Karl: yes.