Characterization of low temperature metallic magnetic calorimeters having gold absorbers with implanted 163Ho ions

For the first time we have investigated the behavior of fully micro-fabricated low temperature metallic magnetic calorimeters (MMCs) after undergoing an ion-implantation process. This experiment had the aim to show the possibility to perform a high precision calorimetric measurement of the energy spectrum following the electron capture of Ho-163 using MMCs having the radioactive Ho-163 ions implanted in the absorber. The isotope Ho-163 decays through electron capture to Dy-163 and features the smallest known Q(EC) value. This peculiarity makes Ho-163 a very interesting candidate to investigate the value of the electron neutrino mass by the analysis of the energy spectrum. The implantation of Ho-163 ions was performed at ISOLDE-CERN. The performance of a detector that underwent an ion-implantation process is compared to the one of a detector without implanted ions. The results show that the implantation dose of ions used in this experiment does not compromise the properties of the detector. Moreover the performance of the detector prototype having the Ho-163 ions implanted in the absorber is already close to the requirements needed for an experiment with sub-eV sensitivity to the electron neutrino mass. Based on these results, an optimized detector design for future Ho-163 experiments is presented. (C) 2013 Elsevier B.V. All rights reserved.