Planck-LFI: Design and Performance of the 4 Kelvin Reference Load Unit
Abstract
The LFI radiometers use a pseudo-correlation design where the signal from the sky is continuously compared with a stable reference signal, provided by a cryogenic reference load system. The reference unit is composed by small pyramidal horns, one for each radiometer, 22 in total, facing small absorbing targets, made of a commercial resin ECCOSORB CR (TM), cooled to approximately 4.5 K. Horns and targets are separated by a small gap to allow thermal decoupling. Target and horn design is optimized for each of the LFI bands, centered at 70, 44 and 30 GHz. Pyramidal horns are either machined inside the radiometer 20K module or connected via external electro-formed bended waveguides. The requirement of high stability of the reference signal imposed a careful design for the radiometric and thermal properties of the loads. Materials used for the manufacturing have been characterized for thermal, RF and mechanical properties. We describe in this paper the design and the performance of the reference system.
Cite
@article{arxiv.1001.4778,
title = {Planck-LFI: Design and Performance of the 4 Kelvin Reference Load Unit},
author = {Luca Valenziano and Francesco Cuttaia and Adriano De Rosa and Luca Terenzi and Alberto Brighenti and GianPaolo Cazzola and Anna Garbesi and Sergio Mariotti and Giordano Orsi and Luca Pagan and Francesco Cavaliere and Roberto Lapini and Matteo Biggi and Enzo Panagin and Battaglia Paola and Chris Butler and Marco Bersanelli and Ocleto D'Arcangelo and Steve Levin and Nazzareno Mandolesi and Aniello Mennella and Gianluca Morgante and Gabriele Morigi and Maura Sandri and Alessandro Simonetto and Maurizio Tomasi and Fabrizio Villa and Marco Frailis and Samuele Galeotta and Anna Gregorio and Rodrigo Leonardi and Stuart Lowe and Michele Maris and Peter Meinhold and Luis Mendes and Luca Stringhetti and Andrea Zonca and Andrea Zacchei},
journal= {arXiv preprint arXiv:1001.4778},
year = {2010}
}
Comments
This is an author-created, un-copyedited version of an article accepted for publication in JINST. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher authenticated version is available online at [10.1088/1748-0221/4/12/T12006]. 14 pages, 34 figures