Hi,
I'm re-sending my list of analyses in a separate email, fixing a couple
things Clem wanted clarified.
Hi All,
I've gone ahead and tried to cover other sims and analyses I've done, in
addition to ones that have actually *caused* spurious BB. I've bolded items
that actually cause excess BB:
1)
http://bicep0.caltech.edu/~spuder/analysis_logbook/analysis/20130125_ellipt…
- comparison of B2 to WMAP temperature maps (thus far only in map space,
not in ell space) rules out few degree FWHM sidelobes with more than ~20%
the power of the main beam. *In fact, the WMAP/B2 comparison looks to even
*suggest* an unmodeled sidelobe.*
- *Given Randol's figure 7* (
http://bicep0.caltech.edu/~spuder/analysis_logbook/analysis/20130124_zemax_…)
*it looks like we *do* have a stacked beam that can be described well as a
Gaussian main beam plus a few degree FWHM, **few percent power sidelobe.*
2)
http://bicep0.caltech.edu/~spuder/analysis_logbook/analysis/20130125_ellipt…
- *A 3 degree FWHM elliptical sidelobe, with 10% the power of the main
beam, 10% ellipticity, 90 degrees offset between A and B, and in which the
ellipses are oriented at 45 degrees to the detector pol angles, induces
false B at about the level we're seeing.* (When the ellipse angle is
coaligned with the detector pol angle, it causes no noticeable spurious
BB.)
- It does almost nothing to any of the BB jackknifes, as we'd expect for a
pure quadrupole.
- *However, even though it causes spurious BB, the TB pattern that results
looks inconsistent with what we observe.*
3)
http://bicep0.caltech.edu/~spuder/analysis_logbook/analysis/20130121_ellipt…
- Turning ground subtraction off impacts the real maps more than sims (i.e.
we're seeing some scan fixed pick up) but appears to be operating at an ell
range below where we're taking to be excess BB.
- Excess BB is probably not due to a failure of ground subtraction.
4)
http://bicep0.caltech.edu/~spuder/analysis_logbook/analysis/20130121_ellipt…
- Spurious BB is not a random fluctuation.
- Spurious BB is definitely not there in Keck.
- Spurious BB does not go away by deprojecting real data with a WMAP W-band
template (but does get a tad noisier.)
4)
http://bicep0.caltech.edu/~spuder/analysis_logbook/analysis/20121210_relgai…
- *Simulating a 5.0% random relgain mismatch causes BB at about the level
we're seeing.*
- *Simulating a 0.5% systematic relgain mismatch causes BB at about the
level we're seeing.*
*- The 0.5% systematic mismatch causes a TB pattern like what we observe.*
*- I might be crazy, but I see an X pattern in the real BB spectrum. I also
see an X pattern in the 0.5% systematic relgain sim.*
- *However, both these effects deproject cleanly. Deprojecting with a
noiseless template yields basically the same deprojected spectrum.*
- Simulating relgain mismatch that reproduces Walt's empirically derived
abscals yields no sprious BB, even without deprojecting.
- A 1 degree systematic pol angle error causes no BB.
5)
http://bicep0.caltech.edu/~spuder/analysis_logbook/analysis/20121217_xtalk_…
- Simulating 1.0% inductive crosstalk (even effectively doing so *before*
elnod relgain calibration, c.f.
http://bicep0.caltech.edu/~spuder/analysis_logbook/analysis/20130121_ellipt…)
yields no spurious BB, owing to strong natural cancellation.
- The correct explanation for that cancellation is here:
http://bicep0.caltech.edu/~spuder/analysis_logbook/analysis/20121228_xtalk_…
6)
http://bicep0.caltech.edu/~spuder/analysis_logbook/analysis/20121217_new_re…
- Deprojecting by scanset leaves discrete B modes that we're identifying as
spurious in place (while adding noise to the BB spectrum, of course.)
7)
http://bicep0.caltech.edu/~spuder/analysis_logbook/analysis/20121210_sim123…
- Adding beamwidth or ellipticity deprojection to A/B offset deprojection
does nothing.
8)
http://bicep0.caltech.edu/~spuder/analysis_logbook/analysis/20121204_sim123…
- Accounting for point sources in V-band that are not the same at 100 GHz
does not alter the BB spectrum, even if it does alter the dk jack.
9)
http://bicep0.caltech.edu/~spuder/analysis_logbook/analysis/20121125_new_te…
- Messing around with simulated template noise and assumed WMAP beam
profile does not really alter the simulated BB spectra.
--
**********************************************************************
Christopher Sheehy - Graduate Student - University of Chicago
University of Minnesota,
Room 220 Tate, 116 Church Street S.E. Minneapolis, MN, 55455
Tel: 612-625-1802 Fax: 612-624-4578 email: csheehy(a)uchicago.edu
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