Self-Calibration of CMB Polarization Experiments
  Precision measurements of the polarization of the cosmic microwave background
(CMB) radiation, especially experiments seeking to detect the odd-parity
"B-modes", have far-reaching implications for cosmology. To detect the B-modes
generated during inflation the Flux response and polarization angle of these
experiments must be calibrated to exquisite precision. While suitable flux
calibration sources abound, polarization angle calibrators are deficient in
many respects. Man-made polarized sources are often not located in the
antenna's far-field, have spectral properties that are radically different from
the CMB's, are cumbersome to implement and may be inherently unstable over the
(long) duration these searches require to detect the faint signature of the
inflationary epoch. Astrophysical sources suffer from time, frequency and
spatial variability, are not visible from all CMB observatories, and none are
understood with sufficient accuracy to calibrate future CMB polarimeters
seeking to probe inflationary energy scales of $10^{15}$ GeV. CMB $TB$ and $EB$
modes, expected to identically vanish in the standard cosmological model, can
be used to calibrate CMB polarimeters. By enforcing the observed $EB$ and $TB$
power spectra to be consistent with zero, CMB polarimeters can be calibrated to
levels not possible with man-made or astrophysical sources. All of this can be
accomplished without any loss of observing time using a calibration source
which is spectrally identical to the CMB B-modes. The calibration procedure
outlined here can be used for any CMB polarimeter.
