Vibration decoupling system for massive bolometers in dry cryostats

TL;DR

This paper presents a passive vibration decoupling system for massive bolometers in dry cryostats, significantly reducing vibrations and noise, thereby enhancing detector performance for low-temperature physics experiments.

Contribution

The study introduces an elastic-pendulum based suspended tower to effectively attenuate vibrations in pulse-tube cryocoolers, improving bolometer energy resolution by up to 40 times.

Findings

Vibration levels are reduced by up to two orders of magnitude above 20 Hz.

Vibration-induced noise is lowered to below 1 μg/√Hz in 1-1000 Hz range.

Bolometer energy resolution improves by a factor of 5 to 40.

Abstract

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 $\sim20$ Hz, for both vertical and radial directions. Thanks to this passive isolation solution, vibration levels, both along vertical and radial directions, below 1 $\mu\textrm{g/}\sqrt{\text{Hz}}$ 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.