[en] The EDELWEISS collaboration is performing a direct search for WIMP dark matter using an array of up to twenty-four 820–890 g cryogenic germanium detectors equipped with a full charge and thermal signal readout. The experiment is located in the ultra-low-radioactivity background environment of the Modane underground laboratory, in the French–Italian Fréjus tunnel. We present the analysis of data obtained in extended data taking periods. WIMP limits, background rejection factors and measurements of cosmogenic activation are used to assess the performance of the third generation of EDELWEISS detectors in view of the search for WIMPs in the mass range from 1 to $20\text{GeV}/{\text{c}}^2$. The developments in progress to pursue this goal in the coming years are also presented.

[en] Pulse-tube based dilution refrigerators are massively employed in low temperature physics. They allow to reduce the running costs and to be operated with unprecedented easiness. However, the main drawback of this technology is the mechanical vibrations induced by the pulse-tube cryocooler. These perturbations can cause extra-noises drastically affecting the detector performance. In this paper, we propose a solution to mitigate the impact of these vibrations by mounting the detectors in an elastic-pendulum based suspended tower. Based on vibration modeling and experimental tests, we show that the vibration levels are attenuated by up to two orders of magnitude at most frequencies, especially above ∼20 Hz, for both vertical and radial directions. Thanks to this passive isolation solution, vibration levels, both along vertical and radial directions, below 1 μ g/√Hz in the frequency range [1–1000] Hz are obtained. This provides a convenient environment to test the ultimate performance of low temperature detectors. As a result, we report an improvement by one to two orders of magnitude on the noise levels of massive cryogenic bolometers, leading to thermal energy resolutions improved by a factor 5 to 40. Finally, we conclude that the energy resolution of our cryogenic bolometers are no longer limited from any residual vibrations, hence allowing the perspective of further improving our bolometer performance in the context of low-mass dark matter searches and neutrino physics applications.

[en] The dry cryostat technology is based on pulse tube cryo-coolers and offers a good alternative to wet dilution cryostats. However, the main drawback is the production of vibrations induced by the pulse tube. These vibrations can be transmitted to the cryogenic detectors mounted in the cryostat and cause extra-noises dramatically affecting their performance. A solution to mitigate the impact of these vibrations is to mount the detectors on a suspended tower. For this purpose, vibrations in a dry cryostat were modeled and preliminary prototypes were investigated in the scope of R&D for the EDELWEISS-III experiment.