Planck pre-launch status: The HFI instrument, from specification to actual performance

¹ Laboratoire d'Étude du Rayonnement et de la Matière en Astrophysique (LERMA), Observatoire de Paris, ENS, UPMC, UCP, CNRS, 61 avenue de l'Observatoire, 75014 Paris, France
² IAS, Institut d'Astrophysique Spatiale, CNRS & Université Paris 11, Bâtiment 121, 91405 Orsay, France
³ Cardiff University, School of Physics and Astronomy, The Parade, Cardiff CF24 3AA, UK
⁴ Institut d'Astrophysique de Paris, UMR 7095, CNRS and Université Pierre & Marie Curie-Paris 6, 98 bis boulevard Arago, 75014 Paris, France
⁵ Department of Physics, California Institute of Technology, Mail code: 59-33, Pasadena, CA 91125, USA
⁶ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
⁷ LAL, Laboratoire de l'Accélerateur Linéaire, CNRS & Université Paris 11, Bâtiment 200, 91898 Orsay Cedex, France
⁸ Institut Néel, CNRS, Univ. Joseph Fourier Grenoble I, 25 rue des Martyrs, BP 166, 38042 Grenoble Cedex 9, France
⁹ CESR, Centre d'Étude Spatiale des Rayonnements, CNRS, 9 Av. du colonel Roche, BP44346, 31038 Toulouse Cedex 4, France
¹⁰ European Space Agency – ESTEC, Astrophysics Division, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands
¹¹ CNES, 18 avenue Edouard Belin, 31401 Toulouse Cedex 9, France
¹² Laboratoire Astroparticule et Cosmologie (APC), CNRS & Université Paris Diderot – Paris 7, 10 rue A. Domon et L. Duquet, 75205 Paris Cedex 13, France
¹³ STFC, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, OX11 0QX, UK
¹⁴ Kavli Institute for Particle Astrophysics and Cosmology and Department of Physics, Stanford University, 382 via Pueblo Mall, Stanford, CA 94305, USA
¹⁵ Dipartimento di Fisica, Universitá La Sapienza, Piazzale Aldo Moro 2, 00185 Roma, Italy
¹⁶ Laboratoire d'Astrophysique Observatoire de Grenoble (LAOG), CNRS, BP 53, 38041 Grenoble Cedex 9, France
¹⁷ European Space Agency – ESAC, PO box 78, 28691 Villanueva de la Cañada, Madrid, Spain
¹⁸ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 OHA, UK
¹⁹ Princeton University, Department of Physics, Joseph Henry Laboratory, USA
²⁰ Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Univ. Joseph Fourier Grenoble I, CNRS/IN2P3, Institut National Polytechnique de Grenoble, 53 Avenue des Martyrs, 38026 Grenoble Cedex, France
²¹ The University of Manchester, JBCA, School of Physics and Astronomy, Manchester M13 9PL, UK
²² Department of Experimental Physics, National University of Ireland (NUI), Maynooth, Co. Kildare, Ireland
²³ Optical Science Laboratory, University College London (UCL), Gower Street, WC1E 6BT London, UK
²⁴ SUPA, Institute of Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
²⁵ Institute of Radiophysics and Electronics, NAS of Ukraine, 12 Proskura St., 61085 Kharkov, Ukraine
²⁶ CEA, CE Saclay, IRFU/Service de Physique des Particules, 91191 Gif-sur-Yvette Cedex, France

Received: 24 July 2009
Accepted: 27 January 2010

Abstract

Context. The High Frequency Instrument (HFI) is one of the two focal instruments of the Planck mission. It will observe the whole sky in six bands in the 100 GHz–1 THz range.

Aims. The HFI instrument is designed to measure the cosmic microwave background (CMB) with a sensitivity limited only by fundamental sources: the photon noise of the CMB itself and the residuals left after the removal of foregrounds. The two high frequency bands will provide full maps of the submillimetre sky, featuring mainly extended and point source foregrounds. Systematic effects must be kept at negligible levels or accurately monitored so that the signal can be corrected. This paper describes the HFI design and its characteristics deduced from ground tests and calibration.

Methods. The HFI instrumental concept and architecture are feasible only by pushing new techniques to their extreme capabilities, mainly: (i) bolometers working at 100 mK and absorbing the radiation in grids; (ii) a dilution cooler providing 100 mK in microgravity conditions; (iii) a new type of AC biased readout electronics and (iv) optical channels using devices inspired from radio and infrared techniques.

Results. The Planck-HFI instrument performance exceeds requirements for sensitivity and control of systematic effects. During ground-based calibration and tests, it was measured at instrument and system levels to be close to or better than the goal specification.