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

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.

Effect of foregrounds on the cosmic microwave background radiation multipole alignment

“…Hence, the signal becomes more prominent as the fluctuations due to detector noise get suppressed. It will, therefore, be very interesting to see how the signal changes with more data from WMAP and Planck (Planck Collaboration 2005;Lamarre et al 2010;Mandolesi et al 2010;Tauber et al 2010).…”

Development of NbSi TES bolometer arrays for submillimeter astronomy

“…The design of space missions dedicated to submillimeter and millimeter broadband or low spectral resolution observations is based on direct detectors limited by the photon noise of the incoming radiation in a diffraction limited beam. This is the case in the Planck-HFI [1] and Herschel-SPIRE [2] instruments. Bolometers are the most sensitive detectors for this purpose.…”

Extragalactic Compact Sources in the Planck Sky and Their Cosmological Implications

“…The other acronyms here used are: N of R (or B) = number of radiometers (or bolometers), EB = effective bandwidth (in GHz). Adapted from [6,7] and consistent with [3,4]. Note that at 100 GHz all bolometers are polarized and the equivalent temperature value is obtained by combining polarization measurements.…”