We study the problem of EB-leakage that is associated with incomplete polarized CMB sky. In the blind case that assumes no additional information about the statistical properties and amplitudes of the signal from the missing sky region, we prove that the recycling method gives the unique best estimate of the EB-leakage. Compared to the previous method, this method reduces the uncertainties in the BB power spectrum due to EB-leakage by more than one order of magnitude in the most interesting domain of multipoles, where is between 80 and 200. This work also provides a useful guideline for observational design of future CMB experiments.
We present near-field radio holography measurements of the Simons
Observatory Large Aperture Telescope Receiver optics. These
measurements demonstrate that radio holography of complex
millimeter-wave optical systems comprising cryogenic lenses, filters,
and feed horns can provide detailed characterization of wave
propagation before deployment. We used the measured amplitude and
phase, at 4 K, of the receiver near-field beam pattern to
predict two key performance parameters: 1) the amount of
scattered light that will spill past the telescope to 300 K and
2) the beam pattern expected from the receiver when fielded on
the telescope. These cryogenic measurements informed the removal of a
filter, which led to improved optical efficiency and reduced sidelobes
at the exit of the receiver. Holography measurements of this system
suggest that the spilled power past the telescope mirrors will be less
than 1%, and the main beam with its near sidelobes are consistent with
the nominal telescope design. This is the first time such parameters
have been confirmed in the lab prior to deployment of a new receiver.
This approach is broadly applicable to millimeter and submillimeter
instruments.
LiteBIRD is a future satellite mission designed to observe the polarization of the cosmic microwave background radiation in order to probe the inflationary universe. LiteBIRD is set to observe the sky using three telescopes with transition-edge sensor bolometers. In this work we estimated the LiteBIRD instrumental sensitivity using its current design. We estimated the detector noise due to the optical loadings using physical optics and ray-tracing simulations. The noise terms associated with thermal carrier and readout noise were modeled in the detector noise calculation. We calculated the observational sensitivities over fifteen bands designed for the LiteBIRD telescopes using assumed observation time efficiency.
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