imagerteleconnotes20180509 [Probe Mission Study Wiki]

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====== Telecon 20180509 ======

Attending: Toki, Shaul, Karl, Qi

Notes by : Qi

=== Agenda===

  * Workshop Follow Up Items 
    * Focal plane mechanical model (SH + UMN); 1/f; temperature stability; detailed cryogenic model;
    * Precession Speed (Kris, Jacques)
    * TDM/FDM noise comparisons (Karl, Roger)
      * Plots of ratio of FDM to TDM noise.  Ratios are NEP^2 (left) and NEP (right)
      * {{::tdm_fdm_ratios.png?direct&600| FDM/TDM noise}}
      * Largest difference is NEP_tot_FDM / NEP_tot_TDM = 1.02.  Or ratio of squares, (NEP_tot_FDM / NEP_tot_TDM)^2 = 1.03

    

=== Notes ===

  * Workshop Follow Up Items 
    * issues of mechanical model: focal plane weight, needs to be revisited and a more realistic model in a few weeks. Heat sinks, mounts etc.
    * **Toki will provide PB focal plane module**
  * 1/f
    * a number of discussions need to be tighten together
    * temperature stability of ADR, Hannes asked to what extend spikes of T affect responsivity
    * we know the magnitude of T spikes; should be straightforward
    * we don’t have complete cryogenic model, temperature loading is **AI for Shaul and jPL**
  * Precession
    * Jacques proposed slow precession; because the scan by scan is closer together, you can make full sky; harder to make continuous map with fast precession
    * Kris prefers fast precesson
  * TDM and FDM
    * We have been assuming sensitivities on FDM coming up from Matt and Franky, but the baseline (physical layout) is TDM
    * Karl's investigation
      * most recent TDM number from Roger
      * photon and phonon calculations between Karl and Roger agree within 1%.
      * ratio of total NEP squared, largest 3%
      * basically FDM is higher by 2-3% level. 
    * Toki: readout noise is function of bolo normal resistance; TDM ~10 ohms, FDM ~1 ohm; TDM higher because it needs to compensate high current noise
    * **Conclusion: same. the numbers we had from FDM are fine.**
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