COrE Science
Documents Post-COrE Activity


COrE builds on the success of Planck/Herschel both in terms of hardware and software/science, reusing many of the subsystems and methods developed by the mm/submm community. In its study of the cosmic microwave background anisotropies, COrE's polarization maps will be of comparable or better quality than the temperature maps that are being delivered by Planck, in spite of the considerably weaker polarization signal. fig10

COrE will achieve this with comparable angular resolution and frequency coverage, but twice the frequency resolution and more than 30 times higher sensitivity than Planck. This improvement is made possible by a massive increase in the number of detectors, from 63 to 6384, operating almost at the photon shot noise limit, as well as from improved detector technology and a longer mission duration. One of the lessons of Planck concerns the abundance of cosmic rays at L2, which would make it hazardous to bank on building much more sensitive detectors behind a colder telescope. fig11

Of course, sensitivity to Cosmic rays will be part of the criteria we shall use in the detailed definition phase for selecting the final detector arrays set-up. COrE's raw sensitivity will be matched by a system-wide approach to reject systematic errors. This concern is actually the primary driver of the selected overall design. fig14

Rather than measuring polarization by subtracting two linearly polarized intensities from different detectors as in Planck, which introduces errors by aliasing temperature anisotropies into a spurious polarization signal, COrE will modulate the polarisation signal by using a rotating half-wave plate as the first element of the optical path from the sky to the detector horns. tab2

This allows polarization to be measured directly on a short time scale and rejects spurious polarization that is inevitably to some extent introduced inside the telescope/detector system.