UCSD-2019: Technical Working Group: LATs

Link back to agenda

Charge

 Conceptual design
 Preliminary design for 3a
 Major decisions: 
   (i) Whether to reuse the Simons Observatory and CCAT-prime telescopes;
   (ii) Whether 2 or 3 LATs will be used in Chile, informed by what receiver design will be implemented;
   (iii) Which LAT optics design (CD vs. TMA) and aperture will be selected for the South Pole;
   (iv) Partial boresight rotation or full boresight rotation for the South Pole LAT;
   (v) Receiver design or designs;
   (vi) Monolithic mirrors and/or ground screens for some or all LATs

Agenda

Thurs, Oct 17 - Large auditorium

• 13:30 (20 min) LAT schedule and major decisions overview - Mike Niemack and John Carlstrom
• 13:50 (15 min) CCAT-prime update, SO LAT update and proposed design studies - Mike Niemack
• 14:05 (15 min) TMA overview - Brad Benson
• 14:20 (10 min) SO LAT 13-tube Receiver Update - Zhilei Xu
• 14:30 (10 min) New LAT cryostat concepts - Brad Benson
• 14:40 (10 min) Fast cooling and warming techniques for a large cryostat - Matt Hollister
• 14:50 (10 min) LAT cryostat sensitivity analyses - Patricio Gallardo
• 15:00 (30 min) Discussion of options, tradeoffs, and next steps - Mike and John coordinating

Remote attendance

Zoom link

Notes

VP: Compile power requirements. Possibly add to same slide deck, or at least link here.

Action items/ R&D needs:

  Loss of warm float zone silicon lens?
  Path to getting detectors: Metal mess filters (now that Sheehy/BNL is out)   Cardiff as sole source would be too risky
  How many metal mesh filters are needed?   SPT manages with one; SO design has three? 
  Need to protect against blue leaks

Decision trees (?)

  Delensing LAT to add weight at degree scales?
  Monolithic mirrors for Legacy Survey LATs?   Does it effect Neff forecasts?  
  Same for "r" --  Need to do the analysis for Neff, and "r"
  

Resonant frequency of both SO/CCAT and TMA design.

Angular Resolution

  Do we want the surveys to match
  Minimum for delensing
  Science case for 10m  in Chile and/or delensing

Margin

 Are we capturing margin? How are we capturing it? Is it safe?
 85 tube design provides some margin

FOV

 Trade off of F# and FOV and modular cryostat design and single cryostat

Cryostat cooling

 Helium gas flow systems are in use by Cuore and SuperCDMS and look very promising for speeding up cooldown times.

TMA vs CD tradeoffs

 Several slides comparing them at end of plenary slides
 TMA has greater optical throughput, although, some of the throughput is traded for enabling a modular instrument design, with 7 separate modules in the nominal TMA configuration
 Nominal TMA instrument design with 7 instruments and 133 single wafer optics tubes approaches mapping speed of CD with a 85 single wafer optics tube instrument
 Need to develop more mature comparison of designs and completing costing of both designs, including instrument development, detector modules, engineering and management of one or more instrument types, etc.

Major upcoming decisions by 2020-Q2

  (i) Whether to reuse the Simons Observatory and CCAT-prime telescopes;
  (ii) Whether 2 or 3 LATs will be used in Chile, informed by what receiver design will be implemented;
  (iii) Which LAT optics design (CD vs. TMA) and aperture will be selected for the South Pole;
  (iv) Partial boresight rotation or full boresight rotation for the South Pole LAT;
  (v) Receiver design or designs;
  (vi) Monolithic mirrors and/or ground screens for some or all LATs