Bolometer's development, with simultaneous measurement of heat and ionisation signals, at Saclay

We report the latest developments of our work on bolometers. Low noise readout simultaneously in charge and heat channel was achieved. Tests were conducted using a 7g bolometer build in Berkeley. Baseline widths 350eV $ (1\sigma , $ phonon) and 1keV $ (1\sigma , $ ionisation) were measured. But the 60keV phonon width was found to be significantly larger than the baseline width. Also the amplitude of ionisation signal was found to drift with time. This effect motivated a detailed study of ionisation detectors at very low temperatures. Behavior of PIN silicon diodes (Hamamatsu) was investigated from room temperature to 3K. First results are shown.