====== Telecon 20180131 ======

Attending: Brian, Julian, Hannes, Amy, Tom, Kris, Shaul, Karl, Qi, Roger, Graca 

Notes by : Karl/Qi \\

=== Agenda===

  * {{::teamxsummary.pdf|Preparing the next Teamx-I}}
  * Report about systematics work (delayed to next week)
  * Cleaned up focal plane {{::focalplane_update_20180131.pdf|version 4}}
  * GRASP {{::bjohnson_01.24.17.pdf| status}}
  
  
=== Notes ===

Preparing the next Teamx-I -- By learning from previous one.
  * response from TeamX, 90 slides on sub-systems. 
  * Section summaries in presentation. No cost discussion today. 15 pages in each sub-system.
  * Need to do homework on some items before next TeamX
  * Systems:
    * I&T will be analyzed in next teamX, was not analyzed here. Still marked as weakness due to complexity.
    * telescope systems at various temperatures (40 K, 4 K, 100 mK) make testing the end to end alignment challenging.
    * Will continue discussion with Bill J. and Tomo next week.
    * Definition: OGSE, optical ground support equipment. Testing equipment that doesn't fly.
    * Future threats: add “cost of cooler”  Comments: this is a cost threat more than a technology threat
  * FP and detectors
    * Str: TES have ground based heritage. detector 1/f shown to be acceptable. future options for MKIDS.
      * Roger will lead 1/f story for final report. Tomasso is running gain variation and per rotation calibration options (assuming 10 mHz 1/f knee)
      * General comment: detector 1/f isn't the only important 1/f term. Other issues (temperature stability) may dominate.
      * Only modulation is sky rotation and scan speed.
    * Weak + future threat: Impact of cosmic rays.
      * Jeff Fillipini has looked into this.  As has Roger.  Roger will lead report summary.
      * Work to reduce impact is also being done at Berkeley.
    * Hannes: What about optical coupling?
      * This hasn't been finalized.  Roger: coupling via lenslets hasn't been shown at high frequencies.
  * Electronics 
    * Weak: Temperature limits. 
      * TeamX assumed what is currently used. but would used space qualified electronics, so this won't be an issue
      * Amy: TeamX usually gives reports to science teams, not reviewers.  Amy is talking with TeamX/NASA to point out that reports need to be crafted so a general review audience understands the issues.  Easily address comments like this risk getting blown out of porportion.
  * Optics:
    * Weakness: maturity of mechanical and thermal design of focal plane.
      * this work is in progress for next TeamX
  * Thermal:
    * 3HE, testing for MIRI was expensive. even if those tests done for PICO, < $1M so ignore it. 
    * Cost is large. $900M for cooling, 50% of instrument cost.  This is largest thermal risk point.
  * Mechanical:
    * Strength: scalable, simple, nothing radical
    * Weakness: optics alignment complex.
      * Address by pointing out WMAP and Planck have done this successfully, should not be weakness, will address in next TeamX
  * Configuration
    * Threat: No volume margin for primary mirror inside the shade
      * Shaul: this is being worked on, should have some margin by next TeamX

Focal Plane V4 (Karl)
  * simpler focal plane, 2 wafer sizes.
  * roughly 1000 more detectors at high frequency.  Sensitivity same. (0.61 uK vs 0.62)
  * FP could go further out in X,
  * Current reflectors need to be larger if we increase focal plane; but we can increase focal plane with current strehl limits.
  * Central wafer issues:
    * multi- and mono band pixels coexist
    * insufficient bond pads for number of bolos on this wafer.
      * 4000 bolos on 4" wafer.  Hannes: fit ~2000 bolos on 6" wafer in past.
      * We are assuming 100 um per bond pad. 4 inch wafer. 
  * 2 mm between tiles, may be too small. For EBEX, ~5 mm.  **Karl** to check
    * Roger to get spacing number from recent BICEP arrays
  * Kris: We need to think about how pixels are aligned to scan direction and how this impacts map making.
    * are we making single detector maps? multi detector maps? do pixels need to follow the same path on the sky as a neighbor?
    * This may require slight rotations of the focal plain.