=== Polarisation sensitivity ===

Some preliminary scan parameters discussed in the [[imagerteleconnotes20170828|"Imager" telecon 28/08/2017]].

In particular Kris plotted some hitcount maps and polarisation angle maps for the following configuration
  * alpha = 22
  * beta = 73
  * T_precession = 11.751 hours
  * T_spin = 121 s

The following illustrates the general scan strategy employed. This is the case for CORE and LiteBIRD too.
{{:scan_params.pdf|}}. (Ignore the instrument design at the origin)

I performed a scan using 36 detectors for a period of $4$ years using the same scanning strategy as Kris. The detectors are spread in 9 rows, each row having an ideal configuration (0, 90, 45, 135 degrees). Each row is separated by ~9' towards increasing beta. The map is then rescaled for 144 detectors.

{{:pol_sens_144_4.png?200|}}

{{:pol_sens_hist.png?200|}}

I took as an example the Band #10 at 107.5 GHz. This has a beam of 7.91'. As a rule of thumb I took the number of samples along the scan direction as 4 per FWHM. This gives me a scan frequency of ~85Hz.

Band #10 quotes a raw sensitivity of 46 muK/sqrt(Hz). To have a comparison with results for CORE I assumed a white noise of 40 muK/sqrt(Hz). These maps can be easily rescaled for the appropriate noise.