Telecon 20180509

Attending: Toki, Shaul, Karl, Qi

Notes by : Qi

• 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)
    • 
    • Largest difference is NEP_tot_FDM / NEP_tot_TDM = 1.02. Or ratio of squares, (NEP_tot_FDM / NEP_tot_TDM)^2 = 1.03

• 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.