Decoupling Pulse Tube Vibrations from a Dry Dilution Refrigerator at milli-Kelvin Temperatures

TL;DR

This paper presents a vibration decoupling system for dry dilution refrigerators that effectively isolates pulse tube vibrations at millikelvin temperatures, enabling sensitive cryogenic detectors to operate with minimal vibration interference.

Contribution

A novel cryogenic spring pendulum was engineered to significantly reduce pulse tube vibrations in dry dilution refrigerators at sub-10 mK temperatures, improving detector performance.

Findings

Attenuation of vibrations by up to two orders of magnitude.

Achieved displacement RMS of ~1 nm axially and 100 pm radially.

Maintained detector baseline resolution of 6.22 eV during pulse tube operation.

Abstract

With the rising adoption of dry dilution refrigerators across scientific and industrial domains, there has been a pressing demand for highly efficient vibration decoupling systems capable of operation at cryogenic temperatures in order to achieve the low vibration levels required for operation of sensitive equipment like cryogenic detectors or quantum devices. As part of the NUCLEUS experiment, a cryogenic spring pendulum has been engineered to effectively isolate pulse tube vibrations by establishing an autonomous frame of reference for the experimental volume, while sustaining temperatures below 10 mK. Attaining attenuation of up to two orders of magnitude within the region of interest of the NUCLEUS cryogenic detectors, we achieved displacement RMS values in the order of 1 nm in the axial direction and 100 pm radially, thereby reducing vibrations below typical environmental levels. Our successful detector operation across multiple cooldown cycles demonstrated negligible sensitivity to pulse tube induced vibrations, culminating in the achievement of an ultra-low $(6.22 \pm 0.07)$ eV baseline resolution on a gram-scale CaWO$_4$ cryogenic calorimeter during continuous pulse tube operation over the course of several weeks.