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Once that the focal plane of the HFI instrument of the Planck mission (launched in May 2009) has reached operational temperature, we have observed the thermal effect of cosmic ray interaction with the Planck satellite, located at Lagrangian point L2. When a particle hits a component of the bolometers (e.g.: thermometer, grid or wafer) composing the focal plane of HFI, a thermal spike (called glitch), due to deposited energy, is observed. Processing these data revealed another effect due to high energy cosmic ray particle showers: High Coincidence Events (HCE), composed of glitches occurring coincidentally in many detectors and with a temperature increase from nK to $$\upmu $$ K after the shower. A flux of about 100 HCE per hour has been calculated. Two types of HCE have been detected: fast and slow. For the first type, the untouched bolometers reach the same temperature as the touched ones in a few seconds which can be explained by a storage of the deposited energy in the stainless steel focal plane. The second type of HCE is not fully understood yet. These effects might be explained by extra conduction from the helium released from cryogenic surfaces, creating a temporary thermal link between the different stages of the HFI. [ABSTRACT FROM AUTHOR]

Abstract: In the standard cosmological scenario tensor perturbations of the metric produce a rotational component in the Cosmic Microwave Background polarization, called B-modes. The expected signal is of the order of ∼0.1μK, well beyond the sensitivity of current experiments. In this paper, we introduce the BRAIN experiment, a bolometric interferometer devoted to measure the B-modes polarization of the CMB from Concordia station in Antarctica. This experiment will take advantage of both high sensitivity of bolometer arrays and low level of systematic effects of interferometers. We report the results obtained during the first campaign we carried out this austral summer at Dome-C. Using a pathfinder experiment, we demonstrated that a cryocooler based cryogenic system can work in such environmental conditions. We also carried out preliminary observations of the atmospheric emission at 145GHz from Dome-C, and during the next campaign we’ll extend the measurements to all the Stokes parameters I, Q, U, V all over the winter. [Copyright &y& Elsevier]

Deals with the design and performances of the Planck High Frequency Instrument (HFI) of the European Space Authority. Importance of the planck cosmic microwave background measurements for cosmologists; Architecture of the Planck HFI.