Calorimetry has been used since the late 1700?s to measure the heat output of physical processes ranging from chemical reactions to the respiration of organisms . Calorimetry is performed by measuring the temperature change caused by heat release into a known media. Using the temperature dependent resistance of a superconductor as a thermometer, we have made calorimetric measurements of the kinetic energy of alpha particles released by nuclear processes with unprecedented resolution. Curiously, the first use of a superconducting detector in 1949 was the detection of alpha particles . However, it is only in the last decade that superconducting detectors have begun to reach their potential, enabling remarkably precise measurements of the energy of individual optical , x-ray , and gamma-ray photons , as well as single biomolecules and alpha particles. Our prototype alpha detector achieves microkelvin temperature sensitivity and is therefore termed a microcalorimeter. We have measured energy resolutions as good as 1.40 +/- 0.07 keV for 5.3 MeV alpha particles, a factor of seven improvement over the best sensors based on the generation and collection of charge in silicon, the present state-of-the-art. Microcalorimeter alpha detectors can therefore provide a more exact and comprehensive picture of nuclear decay processes than is now available. Such an improvement will have an immediate and significant impact on the analysis of nuclear material for safeguards and forensics.
Pub Type: Journals
alpha particle spectroscopy, microcalorimeter, TES