Description
Adiabatic Demagnetization Refrigerator - ADR (08). ADR. 1990s.
The Adiabatic Demagnetization Refrigerator (ADR) flew on the Astro-E satellite, a joint Japanese-NASA X-ray astronomy project. The instrument was designed to cool one of the astrophysics satellite's X-ray detectors down to almost absolute zero. At such low temperatures, the heat generated by a single X-ray photon can be detected and measured. "An ADR works by first using a large magnet to align the magnetic poles (spins) of all the molecules in a block of salt (called the salt pill). The salt pill is then connected to a liquid helium bath via a "heat switch", allowing it to cool to the temperature of the liquid helium (about 1.5 Kelvin). Once it has reached equilibrium with the helium, the heat switch is opened, so that heat can no longer flow between the salt pill and the helium. (Source: https://www.ssec.wisc.edu/media/SSECbrochure2002.pdf). Space Science and Engineering Center, University of Wisconsin-Madison.