Physics & Astronomy Faculty and Staff Publications

Document Type


Publication Date



Recent measurements made with magnetic microcalorimeter (MMC) particle detectors at UNM demonstrated a pronounced sensitivity to noise induced by the rotary valve drive electronics of our Cryomech PT405 pulse-tube refrigerator. After consultation with Cryomech, we undertook to develop a new drive electronics that is fullydifferential, well-grounded, and fully linear, with no digital components all the way out to the wall socket. The design goal was to develop a drive electronics that could potentially be used inside an RF-shielded room for the most sensitive SQUID-based measurements. In this report we describe the circuit design and highly successful test results showing that the sensitive MMC detectors are now unable to tell whether the drive is on or off. The new drive is sufficiently quiet that our MMC noise floor is now set by noise from the commercial readout electronics for the semiconductor thermometers in the cryostat, which has motivated us to develop a new, quiet SQUID-based paramagnetic thermometer described elsewhere in this meeting.

Publication Title

Applied Superconductivity Conference




This work was funded by the U.S. DOE Office of Non-proliferation R&D (NA-22) under grant LL16-MagMicro-PD2La. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Included in

Physics Commons