The achievement of the Planck and Herschel space missions in the submillimeter and millimeter range was made
possible by a continuous effort on detector developments. Now limited by the intrinsic fluctuations of the radiation
coming from the astronomical sources themselves, the sensitivity improvement requires the development of large arrays
of detectors filling the focal plane of the telescopes. We present here the development of a TES array using NbSi sensors
on SiN membranes. The readout electronics is based on SQUIDs and a cooled SiGe ASIC multiplexer. The detector is
coupled with the input radiation by means of antenna. The present goal performance is adapted for the realisation of a
ground based millimeter camera.
Future space experiments will require large arrays of sensitive detectors in the submillimeter and millimeter range.
Superconducting transition-edge sensors (TESs) are currently under heavy development to be used as ultra sensitive
bolometers. In addition to good performance, the choice of material depends on long term stability (both physical and
chemical) along with a good reproducibility and uniformity in fabrication. For this purpose we are investigating the
properties of co-evaporated NbSi thin films. NbSi is a well-known alloy for use in resistive thermometers. We present a
full low temperature characterization of superconductive NbSi films. In order to tune the critical temperature of the NbSi
thermometers down to the desired range, we have to adjust the concentration of niobium in the NbSi alloy. Tests are
made using 4He-cooled cryostats, 300mK 3He mini-fridges, Resistance Bridges and commercial SQUID. Measured
parameters are the critical temperature, the sharpness of the transition. Noise measurements are on-going.
Bolometers cooled to very low temperature are currently the most sensitive detectors for low spectral resolution
detection of millimetre and sub-millimetre wavelengths. The best performances of the state-of-the-art bolometers allow
to reach sensitivities below the photon noise of the Cosmic Microwave Background for example. Since 2003, a french
R&D effort called DCMB ("Developpement Concerte de Matrices de Bolometres") has been organised between different
laboratories to develop large bolometers arrays for astrophysics observations. Funded by CNES and CNRS, it is intended
to get a coherent set of competences and equipments to develop very cold bolometers arrays by microfabrication. Two
parallel developments have been made in this collaboration based on the NbSi alloy either semi-conductive or
superconducting depending on the proportion of Nb. Multiplexing schemes have been developed and demonstrated for
these two options. I will present the latest developments made in the DCMB collaboration and future prospects.