Hi all,
We will have our usual BICEP2 / Keck CMB result telecon in 20 minutes:
12:00 Eastern, 11:00 Central, 9:00 am Pacific
1-866-890-3820 (toll: 1-334-323-7229) Passcode: 59702175#
Clem
--
**********************************************************************
Clem Pryke - Associate Professor - Physics
University of Minnesota,
Room 313 Tate, 116 Church Street S.E. Minneapolis, MN, 55455
Tel: 612-624-7578 Fax: 612-624-4578 email: pryke(a)physics.umn.edu
**********************************************************************
Hi all
Below is a draft abstract I'm planning to submit for SPIE 2014. The
deadline is Monday, and I'm currently in transit to Pole so that makes
coordination a bit difficult. I plan to submit when it is Monday in NZ
time, after ECW issue. I will try to address all comments received by that
time; although, I may not be able to email you back until later. Also, I
haven't slept in ~30 hours, so if this email is incoherent, that's why.
Eric especially let me know if you want me to put something to integrate
better with your abstract. Although I'm not planning to say anything about
BICEP3 besides a brief advertisement, I'm CCing BICEP3 list in case they
want anything more/less.
Title: BICEP2 and Keck Array: Upgrades and Improved Beam Characterization
Finding evidence for inflation by detecting B-modes in the cosmic microwave
background (CMB) polarization at large angular scales remains one of the
most compelling experimental challenges in cosmology today.
BICEP2 and the Keck Array are part of a program of experiments at the South
Pole
whose main goal is to demonstrate the sensitivity and systematic control
necessary
for tensor-to-scalar ratio r <~ 0.01 measurements.
Beam imperfections that are not sufficiently accounted for are a major
potential source of spurious polarization that could interfere with that
goal.
The strategy of BICEP2 and Keck Array is to completely characterize their
telescopes' polarized beam response with a combination of in-lab,
pre-deployment, and on-site calibrations.
I will report the status of these experiments, focusing on continued
improved understanding of their beams.
Far-field measurements of the BICEP2 beam with a chopped thermal source,
combined with analysis improvements, show that the level of residual
beam-induced systematic errors is below r ~ 0.01.
Similar measurements have been made for the Keck Array.
On-site measurements of Keck Array showed unexpected side lobes that were
terminating on the absorptive telescope forebaffles.
Follow-up lab measurements confirmed these side lobes were due to
inadequate blackening of the cryogenic telescopes, and in late 2013 the
five telescopes were upgraded on site with improved interior baffles.
These baffles have substantially reducted total optical loading, leading to
a ~ 10% increase in mapping speed for the 2014 observing season.
The sensitivity of Keck Array continues to improve: for the 2013 season it
was 9.5 uK*sqrt(s) NET.
In 2014 we converted two of the 150 GHz cameras to 100 GHz for foreground
separation.
The sensitivity at 100 GHz is ~ 20 uK*sqrt(s) per camera.
We have shown that the BICEP2/Keck telescope technology is sufficient for
the goal of measuring r at the 0.01 level.
We expect to publish such measurements soon.
Furthermore, the program is continuing with BICEP3, a 100-GHz telescope
with ??? detectors.
Immanuel Buder
Postdoctoral Fellow
Harvard-Smithsonian Center for Astrophysics
(office) 617 495 7567
(office) 160 Concord Ave., M-114C
(mail) 60 Garden St. MS 42
Cambridge, MA 02138
ibuder(a)gmail.com
<ibuder(a)cfa.harvard.edu>
Hi all,
We will have our usual BICEP2 / Keck CMB result telecon in 35 minutes:
Tues, 29 Oct 2013 - 12:00 Eastern, 11:00 Central, 9:00 am Pacific
1-866-890-3820 (toll: 1-334-323-7229) Passcode: 59702175#
Clem
--
**********************************************************************
Clem Pryke - Associate Professor - Physics
University of Minnesota,
Room 313 Tate, 116 Church Street S.E. Minneapolis, MN, 55455
Tel: 612-624-7578 Fax: 612-624-4578 email: pryke(a)physics.umn.edu
**********************************************************************
I have completed the plan below. The result appears negative - adding enough
extra noise to elliminate the B2xB2-B2xRx1 discrepancy blows the Rx1xRx1 auto
spectra out of the water over the same range of angular scale as our nominal
detection.
http://bicep0.caltech.edu/~spuder/analysis_logbook/analysis/20131118_rp3
Clem
Subject: Re: [Bicep2-list] posting on B2xB1
From: John Kovac <John.Kovac.Guest(a)usap.gov>
Date: Tue, 12 Nov 2013 21:18:29 +1300
To: Clem Pryke <pryke(a)physics.umn.edu>, jmkovac(a)cfa.harvard.edu
Cc: Chao-Lin Kuo <clkuo(a)stanford.edu>, Walt Ogburn <ogburn(a)stanford.edu>,
bicep2-list <bicep2-list(a)lists.fas.harvard.edu>
> I don't see anything since John's email on
> Friday morning - which I mostly agree with.
No, no one responded. Thank you for taking it on--your plan below
sounds good.
J
On 11/12/13, 5:26 PM, Clem Pryke wrote:
> I am just getting back to this - I don't see anything since John's email on
> Friday morning - which I mostly agree with.
>
> If the hypothesis is that there is a real signal plus a systematic in Rx1
> which cancels it then a concrete test plan is as follows:
>
> - Scale the r=0.1 sims to r=0.3 and add to the signal+noise for all receivers
> - In the Rx1 sig+noise sims scale the noise up until the B2xB2-B2xRx1 spectral
> jack is not unlikely (i.e. the systematic is being modelled as just extra
> noise).
> - Look if the Rx1xRx1 auto spectrum then shows a detection - which it very well may because it will be debiased with the *unscaled* noise which we believe to actually be present in Rx1.
>
> Walt/anyone: are you working on this or something similar? If not I will get on it tomorrow morning.
>
> Clem
--
**********************************************************************
Clem Pryke - Associate Professor - Physics
University of Minnesota,
Room 313 Tate, 116 Church Street S.E. Minneapolis, MN, 55455
Tel: 612-624-7578 Fax: 612-624-4578 email: pryke(a)physics.umn.edu
**********************************************************************
