Selfcalibration: an efficient method to control systematic effects in bolometric interferometry
Abstract
Context. The QUBIC collaboration is building a bolometric interferometer dedicated to the detection of Bmode polarization fluctuations in the cosmic microwave background.
Aims: We introduce a selfcalibration procedure related to those used in radiointerferometry to control a wide range of instrumental systematic errors in polarizationsensitive instruments.
Methods: This procedure takes advantage of the need for measurements on redundant baselines to match each other exactly in the absence of systematic effects. For a given systematic error model, measuring each baseline independently therefore allows writing a system of nonlinear equations whose unknowns are the systematic error model parameters (gains and couplings of Jones matrices, for instance).
Results: We give the mathematical basis of the selfcalibration. We implement this method numerically in the context of bolometric interferometry. We show that, for large enough arrays of horns, the nonlinear system can be solved numerically using a standard nonlinear leastsquares fitting and that the accuracy achievable on systematic effects is only limited by the time spent on the calibration mode for each baseline apart from the validity of the systematic error model.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 February 2013
 DOI:
 10.1051/00046361/201220429
 arXiv:
 arXiv:1209.4905
 Bibcode:
 2013A&A...550A..59B
 Keywords:

 instrumentation: polarimeters;
 instrumentation: interferometers;
 cosmic background radiation;
 inflation;
 methods: data analysis;
 Astrophysics  Instrumentation and Methods for Astrophysics;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 11 pages, 4 figures