Telecon 20180516

Attending: Brian, Tom, Kris, Hannes, Jacque, Shaul, Karl, Qi,

Notes by : Qi

• Precession Period (Kris, Jacques)
  • 10 hour precession period: (.png)
  • 48 hour precession period: (.png)
  • More Slides (.pdf)
• Noise/Bands Figure (.pdf)
• Noise Requirements vs Best Case Estimate (BCE)
  • Proposal: Req = BCE*rt(2)/0.9, independent of frequency
  • rt(2) because “Planck achieved noise within ~20% of BCE” (to be checked)
  • 0.9 because the cost models assume 90% yield
  • first factor is applied on individual detectors, second factor on the array.

• Precession Period (Kris)
  • Shaul: we've debating whether fast or slow precession; Jacques's argument was too fast precessions give large gaps
  • high-resolution, 1.6 arcmin simulations, single detector
  • 10 hours vs 48 hours; 2,4,5,…, 365 days of scanning
  • blue (or gray on right side) is either 0 or just a few hits; yellow is a few hundred
  • short-time plots show difference, but long-time show less difference
  • Kris argues that either option is good at some locations; we need to specify science goals before we really answer this question. Also, since we are using action-wheels, we can fairly easily adjust precession in space. This is different from Planck. Planck did have some big gaps.
  • Jacque argues that we need to compare gap size with beam size. 48 hours comes from CORE study, which has 2-min spin rate and 96-hour precession.
  • conclusion: the report should probably say “there are a range of considerations, for either 10 or 48 hours”
  • Shaul: the fly-wheel will be able to do the change of precession; slow-motion can also be done.

• Noise Requirements vs Best Case Estimate (BCE)
  • Best case estimate: not everything is most optimistic, just reasonable.
  • Shaul proposed BEC/sqrt(2)*0.9
    • root 2 is coming from Planck, which had achieved within 20% BCE.
    • 0.9 is 90% yield of pixels; BCE is optimistic on 100%-yield assumption
    • This number is for feedback loop to science teams.
    • Jacques: CORE did something similar, no major impacts on science

• Noise/Bands Figure
  • goal: a standard visual
  • needs to clarify things, needs suggestions