Neutrino mass measurements with cryogenic microcalorimeters

We have concluded the first pilot experiment for the direct measurement of the neutrino mass, which has made use of small cryogenic microcalorimeters with superconducting rhenium metal as beta source and detector. This first successful application of cryogenic micro-calorimeters to neutrino mass search pushed us to plan a new experiment that aims to investigate the sub eV/c2 range. The new calorimetric rhenium detectors under development must have the challenging energy resolution of about 1 eV. With the rhenium experiment, we also found a new effect on beta decay called Beta Environmental Fine Structure (BEFS). This is caused by the quantum interference of the beta-electron waves reflected by the neighboring atoms. Because the BEFS is sensitive to the microcrystalline structure, it can be employed for material science studies as a possible alternative to the EXAFS effect in the Synchrotron light