After the great success of NASA's satellite missions COBE and WMAP, the Planck mission represents the third generation of mm-wave instruments designed for space observations of CMB anisotropies. Two instruments, the Low-Frequency Instrument (LFI) and the High-Frequency Instrument (HFI) will produce CMB maps with unprecedented angular resolution, sensitivity and frequency coverage. This ambitious task will be achieved by using low noise HEMT detectors cryogenically cooled at ~20K for the LFI and bolometric detectors cooled at 0.1K for the HFI; in particular, the LFI is based on pseudo-correlation receivers in which the sky signal is continuously compared to a cryogenic reference load in thermal contact with the HFI 4K stage. Such high sensitivity in Planck detectors calls for a strict control of systematic effects, which must be kept at μK level in the final maps; this in turn imposes tight requirements on the thermal and electrical stability of the different stages in the instrument. In this paper we discuss a study of the impact of thermal fluctuations at the level of the 20K cooler cold-end on the Planck-LFI measurements and present some viable solutions that have been adopted to keep the residual systematic error within the required values for Planck-LFI.

Thermal stability in precision cosmology experiments: the Planck LFI case / L. Terenzi, A. Mennella, M. Bersanelli, N. Mandolesi, G. Morgante, M. Prina, M. Tomasi, L. Valenziano. - In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH. SECTION A, ACCELERATORS, SPECTROMETERS, DETECTORS AND ASSOCIATED EQUIPMENT. - ISSN 0168-9002. - 520:1-3(2004), pp. 393-395. [10.1016/j.nima.2003.11.343]

Thermal stability in precision cosmology experiments: the Planck LFI case

A. Mennella
Secondo
;
M. Bersanelli;M. Tomasi
Penultimo
;
2004

Abstract

After the great success of NASA's satellite missions COBE and WMAP, the Planck mission represents the third generation of mm-wave instruments designed for space observations of CMB anisotropies. Two instruments, the Low-Frequency Instrument (LFI) and the High-Frequency Instrument (HFI) will produce CMB maps with unprecedented angular resolution, sensitivity and frequency coverage. This ambitious task will be achieved by using low noise HEMT detectors cryogenically cooled at ~20K for the LFI and bolometric detectors cooled at 0.1K for the HFI; in particular, the LFI is based on pseudo-correlation receivers in which the sky signal is continuously compared to a cryogenic reference load in thermal contact with the HFI 4K stage. Such high sensitivity in Planck detectors calls for a strict control of systematic effects, which must be kept at μK level in the final maps; this in turn imposes tight requirements on the thermal and electrical stability of the different stages in the instrument. In this paper we discuss a study of the impact of thermal fluctuations at the level of the 20K cooler cold-end on the Planck-LFI measurements and present some viable solutions that have been adopted to keep the residual systematic error within the required values for Planck-LFI.
Cosmology ; Cosmic microwave background observation ; Instrumentation ; Detectors
Settore FIS/05 - Astronomia e Astrofisica
Settore FIS/01 - Fisica Sperimentale
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/198944
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