Empirical modelling of the BLASTPol achromatic half-wave plate for precision submillimetre polarimetry

Moncelsi, Lorenzo and Ade, Peter A R and Angile, Francesco E and Benton, Steven J and Devlin, Mark J and Fissel, Laura M and Gandilo, Natalie N and Gundersen, Joshua O and Matthews, Tristan G and Netterfield, C Barth and Novak, Giles and Nutter, David and Pascale, Enzo and Poidevin, Frederick and Savini, Giorgio and Scott, Douglas and Soler, Juan Diego and Spencer, Locke D and Truch, Matthew D P and Tucker, Gregory S and Zhang, Jin (2013) Empirical modelling of the BLASTPol achromatic half-wave plate for precision submillimetre polarimetry. Monthly Notices of The Royal Astronomical Society, 437 (2014). pp. 2772-2789.

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Abstract

A cryogenic achromatic half-wave plate (HWP) for submillimetre astronomical polarimetry has been designed, manufactured, tested and deployed in the Balloon-borne Large-Aperture Submillimeter Telescope for Polarimetry (BLASTPol). The design is based on the five-slab Pancharatnam recipe and itworks in thewavelength range 200–600 μm, making it the broadestband HWP built to date at (sub)millimetre wavelengths. The frequency behaviour of the HWP has been fully characterized at room and cryogenic temperatures with incoherent radiation from a polarizing Fourier transform spectrometer. We develop a novel empirical model, complementary to the physical and analytical ones available in the literature, that allows us to recover the HWP Mueller matrix and phase shift as a function of frequency and extrapolated to 4 K. We show that most of the HWP non-idealities can be modelled by quantifying one wavelength-dependent parameter, the position of the HWP equivalent axes, which is then readily implemented in a map-making algorithm. We derive this parameter for a range of spectral signatures of input astronomical sources relevant to BLASTPol, and provide a benchmark example of how our method can yield improved accuracy on measurements of the polarization angle on the sky at submillimetre wavelengths.

Item Type: Journal Article
Keywords: magnetic fields, polarization – balloons, instrumentation: polarimeters, techniques: polarimetric, submillimetre: ISM
Faculty: Faculty of Science & Technology
Depositing User: Unnamed user with email jin.zhang@anglia.ac.uk
Date Deposited: 25 Nov 2016 15:11
Last Modified: 25 Nov 2016 15:11
URI: http://arro.anglia.ac.uk/id/eprint/701166

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