Telecon 20180228

Attending: Bill, Tom, Kris, Hannes, Shaul, Karl, Qi

Notes by : Qi

• Telescope and Instrument I+T (Tomo and Bill)
  • Tomo's slides (.pdf)
  • Receiver, Bill Jones (.pdf)
  • I&T, PICO specific, Bill (.pdf)
• Planck decontamination, cooling, and in-orbit checkout
• Focal Plane configuration + ADR location + GRASP update (Karl)
  • Focal plane slides (.pdf)
  • Adjusted system to alpha = 30, beta = 65.
    • ADR position image: (.jpg)
  • GRASP quick update. Slides just in case: grasp_status (.pdf)

• Planck decontamination, cooling, and in-orbit checkout
  • Someone needed to write ~ 1 paragraph. Charles Lawrence suggested.
  • From Bill:
  • CPV (commissioning and performance verification) at L2
    • Telemetry checkout, cryogenic check, normal receiver operation etc.
    • For PICO, the best mode needs to be decided; spinning or spinning + precession; we have to spin to stabilize. Different spin rate is something interesting.
  • baking primary during launch to remove water not part of CPV
  • Passively cool, during the flight to L2

• Telescope and Instrument I+T (Bill):
  • Receiver
    • Planck, did not include a lot of stuff prior to 2005
    • overview in page 1
    • some periods below:
      • Sep, 2005
        • Cryogenic chain, delivered and tested
      • Mar, 2006
        • HFI focal plane integration, 2 K bath, 100 mK, less than a week of testing; primary goal, show cryogenic works; gross noise check
      • May,2006
        • cryogenic, photometry, cooling down to 40 K, measuring surface separation
      • July,2006
        • same run as above, to do calibration, 20 day period, not fully integrated system, 2K to 100 mK, nothing at room T
        • Much longer time is better, 20 days is really risky
      • may,2008
        • final cool down, only time of fully integrated test
        • not designed to do any useful testing, cold load in front of focal plane, T is not stable, so no noise testing
      • may 2009
        • launch
  • I&T, PICO specific
    • counting back from launch, overview
      • T-4 years: devices level detectors
      • T-3years: proving sub-k cryogenics, maybe spectroscopy and noise testing;
        • the sooner you get integration tests, the better; example: problem related to wiring, you won’t know until you get the full integration
        • Planck did not have HFI+LFI fully test; 100 mK, 4K, more natural to sepaerate
        • Cryogenic photogrammetry of telescope and truss, very important for Planck
      • T-2 years: entire cooling chain
      • T-1years: require a proper chamber
    • Details:
      • T-3 years:
        • full focal plane, not the entire cooling chain
        • due to warm primary, be careful of how to mimic background operational conditions at L2
        • 3 mK fluctuation on 3K, heater, pump helium back; 10% percent level; as if we are observing CMB, for non-linearity etc.
        • no mirrors, find the right chamber, ~meter level, time being cold should not be less than 1 month
        • Polarimetric calibration ● Spectroscopic calibration
        • two runs because of some expectation of something not working
        • Planck never measured Spectroscopic with mirrors
        • Planck Polarimetric, used those obtained during device level testing; it’s tricky to do it with fully integrated system. Very difficult measurements
        • Cryogenic photogrammetry of telescope and truss [Large 300-40K chamber, 1 mo], may have to do mirrors separately for PICO, 30K, 4K
      • T-1 years:
        • cool the whole thing down, long run
        • Because of TES, optical loading, to see Psat
        • If we convince ourselves that we can do Polarimetric calibration ● Spectroscopic calibration on the whole system, we should
        • Shaul: depending on the size of chamber
        • Bill: do the math, and believe device level testings
        • Planck was lucky, given the limited time of fully integration testing.
        • Shaul: polarization modulation efficiency, one would calculate well based on the testings without mirrors.
        • Bill: angular calibration, independent may be demanding.
        • constrained bandpass mismatch, using data itself. It’s a big question to reach r<10^-4.
        • 2 month is the tight. sort of Planck schedule. better to add 1 month to do testing, not sure the cost.
        • in flight correction of HFI, the challenge is it’s difficult to do spectroscopy tests on the whole, which are in fact dependent on the whole system.
      • cost, driver, 3 level of testing set ups
        • modest, device, institutions
        • large, full focal plane, calibration equatment needed, time needed
        • 3rd, big chamber, fully integrated, time and calibration we want to test.
        • Timing is likely to drive the cost