Decay Energy Spectroscopy with Microcalorimeters for Nuclear Physics and Safeguards Applications
Alexander Kavner, University of Michigan
Cryogenic Magnetic Microcalorimeters (MMCs) operating at milli-kelvin temperatures are capable of radiation detection with ultra-high energy resolution and precision. The detectors utilize superconducting magnets and paramagnetic materials to measure the micro-heat produced by individual nuclear decays and interactions. We have developed an MMC-based decay energy spectroscopy (DES) technique where radionuclide sources are embedded within the detector. DESenables sensitivity to decay radiation in the form of alphas, betas, conversion electrons, nuclear recoils, and soft X-rays to be detected with 100 percent efficiency, producing spectra with single peak(s) at the total decay energy of each nuclide. Isotopic composition can then be identified via unique decay energies. We have utilized MMCs and the DES technique to perform a novel, 1 percent uncertainty, half-life measurement of 146 Sm, with an important isotope for establishing a timescale of solar-system formation. Previously the half-life was not known better than 30 percent. We are also working to develop techniques to perform nuclear material analysis on plutonium and mixed actinide samples. The composition uncertainties of these measurements are of order less than 1 percent. We have demonstrated that samples can be prepared, analyzed, and retrieved on short time scales. This technique enhances and complements current nuclear safeguards and forensics capabilities.
Abstract Author(s): A.R.L. Kavner, I. Jovanovic, S. Friedrich, G.B. Kim