Telecon 20180404

Attending: Kris，Brian, Toki, Tom, Jeff, Shaul, Karl, Qi

Notes by : Qi

• SPIE Papers
  • Sutin Abstract (.docx)
  • Young Abstract (.doc)
• TeamX
  • Final Focal Plane configuration (.pptx)
  • Latest noise budget V3.2 (.xlsx)
• Setting Margins
  • PICO Noise Assumptions (.pptx)
• Any suggestions for workshop? (.pdf)

• SPIE
  • in June, mostly technical
  • Apr 9, deadline for finalizing the author list and material

• TeamX meeting
  • 2nd Instrument meeting; Mission meeting
  • Overall cost is the the most important product
  • no significant revelation
  • Focal plane
    • converged to one configuration; most compact, proper strehl ratio for high frequency
    • the other two, we have to change the optical design, to accommodate with high frequency
    • this focal plane has largest number of detectors; the difference compared to other two is very small though.

• Noise budget
  • V3.2: very little change from V3.1; noise 0.63 uK arcmin before, now 0.61 uK arcmin
  • compare values with CORE and LiteBird calculation, single detector
  • we are using two independent codes to calculate. Karl at UMN; Roger at JPL. Agree within 5%, slightly difference. Reasonable confidence.
  • various assumptions
    • to what extend our assumptions agree with other experiments
    • in some bands, noise lower than LIteBird, some bands higher than LiteBird.
    • everything seems consistent, no major change
    • Psat, safety factor of 2, we haven chosen a factor of 2, it’s used by JPL folks, also by SPIDER AND KECK. We thought it’s reasonable.
    • Quantitative calculations will be done by next week: what T of elements (mirros) could bring us to a factor of 2
    • Efficiency
      • It varies between the bands
      • Detector: lenselet + antenna + bolo, 70%
      • Edge Taper: center 10 db, lower band and higher band have different values; low, center, high: 70%, 90%, 99%.
      • End to end, 50-70%
      • Optical efficiency can mess up the estimate on safety factor
    • Emissivity
      • We are using measured emissivity from Planck. We already know, for highest bands, we may need to change to be more conservative

• Margins
  • Space Mission, “current best estimate”, e.g. 100% yield; we are not likely to do better than 0.61 uK arkmin
  • What margin is the judge, successful or not.
  • Two paths:
    • 1. start with assumptions
      • each one assumption
      • “worst case”
    • 2. We can propagate backs from sigma_r 2*10^-5.
    • 3. maybe a 3rd one, some factors on NET.
    • Kris: instrument is one thing, how to get data to science is another
    • Raphael used mapping speed, assuming delensing on our own resolution. 1*10^-4 is the limit that Shaul said in AAS, which has margins from calculated value 2*10^-5.
      • It's not a trivial calculation
  • LiteBird
    • does have margins
    • “large sections”, different categories, based on what's typically achieved in lab and by ground experiments
    • quote r with margin in it
    • nominal performance and worst performance. Give both to science team. Worst case did not give too much science. Lately, increase number of detectors to improve “worst case”
  • Shaul is going to check with Planck team

• Workshop
  • suggestions:
    • Kris: 1) without modulator 2) arguments on margins