High-resolution X-ray and gamma-ray detection using cryogenic magnetic calorimeters

Magnetic calorimeters, based on the properties of localized paramagnetic io ns embedded in metals, have been developed in recent years for X-ray and ga mma-ray detection. In this type of detector the absorbed energy is determin ed by the change of magnetization, which can be measured with very high sen sitivity using a SQUID. The strong coupling of the conduction electrons to the paramagnetic ions leads to very short thermalization times even at low temperatures, so that detectors with reasonably high counting rates can be constructed. Linearity of the response of such a detector is ensured by the high heat capacity of the sensor material. Adjusting the spin concentratio n and the amplitude of the external magnetic field permits the optimization of the calorimeters for work in a wide range of temperatures. We present r esults obtained recently with different prototype detectors and discuss pos sible applications for magnetic calorimeters. (C) 2000 Elsevier Science B.V . All rights reserved.