CMBPol Mission Concept Study
Telecon notes
18 March, 2008

Participants:
Borrill, Cooray, Hanany, Keating, Lawrence, Lee, Meyer, Page, Seiffert

Announcements:
Jullian Borrill is working on a startup request for a NERSC allocation in support for CMBPol mission study work. The goal is to provide computing time for CMBPol studies.

Workshop updates: 

Dodelson writes: Great response for theory workshop up to now. Check out http://astro.fnal.gov/cmb/ for list of topics and attendees. 

Mission Study - Mike Seiffert:
The starting point is a model of a potential radiometer focalplane based on extrapolations of existing polarimeter pixel characteristics. Total radiometer sensitivity and power dissapation is determined by the number of pixels at various frequencies. Optimization of this system given foregrounds, scanning strategy and total allowable focalplane dissipation is carried out. For example using 5 frequencies from 30 to 130 GHz and setting the total sky (CMB+foregrounds) signal to noise to be constant with frequency and holding the total 20K powerload to 4 Watts results in a 70 GHz sensitivity of 0.16 muK RMS per 1 degree pixel. 

Studies to characterize the costing of such a mission including cooler and optics has not been done. Progress in the next 10 years would center on optimizing the coolers and bringing the amplifier noise and power dissipation down and the other technologies which would make such a mission possible.

Discussion:

Borrill: Important to specify data rate and instrument papameters
Hanany: What is the advantage of such a mission when a bolometric mission could provide 20 nK RMS 1 degree pixeis:
Seiffert: 20K focalplane may be easier, detector technology exists, mission potentially cheaper. At low frequencies the amplifiers and bolometers are close in sensitivity. The foregrounds may really be easier at low frequencies.
Lawrence: Planck will go a long way to telling us about the foregrounds and how to optimize for the foregrounds.
Page: We can tell a lot with the data we have in hand now. 
Meyer: Hope that we woule be able to determine the cooler cost and weight to make a HEMT mission viable on the one hand and the cost and weight of the optics to make a higher resolution mission possible on the other hand. 
The coupling of the understanding of the foregrounds and ancillary science with the frequency coverage and beam are items that cross cut this study. We are in a unique position to look at these questions from one end to the other.


Budget update:

Meyer continues to work to get the budget inline. CoI's will be getting budget revisions this week.