Cosmic ray disturbances in thermometry and refrigeration

Cosmic-ray heating effects have so far never been considered seriously. In this comment, experimental evidence is presented about charged particle heating of a carbon resistor thermometer below 20 mK, immersed in dilute solution in the mixing chamber of a dilution refrigerator. It is suggested to examine the residual heat leaks to massive nuclear demagnetization refrigerators, in view of possibly seeing heating bursts originating from very high energy particle showers. (author). 1 ref.; 1 fig