Speaker
Description
For over 20 years, the BICEP series of telescopes has been observing CMB polarization from the South Pole with ever increasing sensitivity, continually improving the leading constraints on primordial gravitational waves and the faint B-modes they would produce at degree scales. The measurement challenge is immense. As sensitivities continue to increase, from existing datasets which constrain the tensor-to-scalar ratio $r$ at the level of $\sigma(r) \sim 0.005$ to goals of the current surveys to reach $\sigma(r) \sim 0.001$ or below, systematic effects must be controlled to nano-Kelvin levels, requiring many orders of magnitude suppression of environmental astrophysical contaminants. Building on our program's experience of these measurements, a sixth-generation BICEP telescope, called BA4-90/150, will be commissioned in 2027. In this talk I will discuss how BA4 will continue to improve BICEP's standard of sensitivity and systematic control, while precision in-field calibration measurements of the BICEP program will continue to inform mitigation strategies in our cosmological analysis and robustly characterize the upper limits of residual systematic uncertainty for measurements of $r$. Precision absolute polarization angle calibrations also promise to improve measurements of cosmological birefringence.
| Other topic / keywords: | cosmological birefringence |
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