Telecon 20180314

Attending:Brian, Roger, Toki, Shaul, Kris, Karl, Qi, Amy

Notes by : Qi

• TeamX studies (next two weeks)
• Calibration and performance verification (.pdf)
• Temperature Stability
• Latest focal plane, instrument alpha, beta, ADR location, GRASP . . .
  • Focal plane slides (.pdf)
  • Adjusted system to alpha = 30, beta = 65.
    • Changes made: (.png)
  • GRASP status: grasp slides (.pdf)

• TeamX
  • Next week: Instrument study
  • 2nd week: Mission study
  • The results will go to independent cost analyzer
  • TeamX team is tailoring slides; we have option to add a narrative document
  • Shaul will send note about existence of telecons after TeamX

• CPV
  • For Mission study
  • Planck had this phase, we will have too; we need to include this phase in our timeline
  • Based on ‘Planck HFI Core Team’ et al. 2011
    • CPV = “6 weeks before first survey”
    • Last two weeks of data have been included into the “1st survey data”
    • Slide3, Planck CPV
    • Slide4, PICO; Shaul only spent a few minutes; we can and probably should add more items
    • Cosmic rays
      • “What would change given the possible measurements during CPV?”“Nothing” except some characterizations
• Temperature Stability
  • Roger and Shaul are communicating; the results will go to Cryogenic Design
  • Roger
    • T stability of focal plane
    • ADR, thus we should not assume same stability as Planck.
    • The concern is that the real numbers we use
      • Loop gain = 1000 from thesis, very high, Roger think L~10 is more reasonable.
      • Alpha is also too large by a factor of 10 or more.
      • Toki agrees with Roger. Alpha is about ~100.
    • For LiteBird, super relaxed, requirement For T stability is very low.
    • Shaul: LiteBird no ADR, we don’t know what it should be for continuous ADR.
    • Roger: 1%Single ADR would heat the focal plane.
    • Shaul: timescale matters. We can calibrate on dipole. If the fluctuation is fast, then it’s problematic. On spin-spin basis (~1min), we would have dipole calibration. Timescale is unknown for CADR.
    • LiteBird: single shot, not ADR. ADR had been discussed. Toki is going to dig out more information.
    • Shaul: we will get information from Toki aobut LiteBird.
    • Roger: by next week, If we have a figure from Toki on requirement, we can have a number, we can put a reqirement on the fridge. Temperature constrained within some range.We are looking for “changes in detector response over some timescales”.
    • Roger: if you cycle ADR, before next cycle, you can do calibration.
    • Amy: on one hand, amount of requirement on changing responsivity and time scales; use calculation to infer Bath stability and timescale; we don’t need to go into too much details at this stage. More importantly, Decal Panel, risky or not.
    • Shaul: have no idea wether this is an issue or not; we don’t know ADR, fluctuation and timescale. Goddard may care cost, then they give us amplitude and timescale. Shaul will follow up.
    • “Common modes”, If the two polarization go down and up together.
    • Shaul will write to Tom, and with information Toki will proved, we will see what we need.
    • Kris: since this is a study, other techonologies could be mentioned.
    • Shaul: we will say there are emerging technolgy that may end being competative.

• Focal Plane Status(Karl)
  • Slide2: nominal focal plane
  • Slide3: along the scan direction
    • Questions: 1) slight wider, looks more wasted space; 2)Center: pink is high-frequency, needs to be in the contour; we can futz around to make it good.
  • Slide4: two cases comparison.
  • Amy: either should be fine.
  • Slide5: bump bond; stack multiple TDM chips below wafer.

• GRASP:
  • Shaul: we understand now, working on slides.