The Microcalorimeter Array for a Rhenium Experiment (MARE) is an experiment for the direct detection of the neutrino mass by studying the beta decay of 187-Re with cryogenic microcalorimeters. The experiment is divided in two steps, MARE I, the heir of the MANU and MIBETA experiments with a sensitivity of ~2 eV and MARE II with a sensitivity of 0.1-0.2 eV.
This award will provide funding to continue these scientists' current effort with the MARE I investigation and to help build a prototype detector for the full MARE II. The MARE I effort involves the Universities of Miami and Florida in collaboration with the University of Genoa, Italy. It will ultimately consist of tens of iridium transition edge sensors (TES) microcalorimeters coupled to rhenium crystal absorbers. The first detectors are being assembled at this time and data acquisition was expected to start by the end of 2009. They have been supporting the development and fabrication of prototype detectors and have started building an infrastructure for the handling and analysis of the data, including a full scale experimental simulation. During the proposed investigation, they will support the acquisition and analysis of the data. The data acquisition is expected to extend though the second year of this investigation, while the third year will be dedicated to the data analysis. In parallel to continuing their support of the MARE I investigation, they plan to work toward the full MARE II investigation. This is a much larger scale investigation that will ultimately involve several groups in the US and Europe. The investigation will be carried out in close collaboration with other members of the collaboration.
Determining the value of the electron neutrino mass has a broad impact on various fields of physics, from particle and nuclear physics and cosmology. The microcalorimeter technology being developed has direct applications in dark matter searches, detectors for non-proliferation investigations, astrophysics and nuclear physics. The investigation will be carried out with the active support of graduate and undergraduate students that will be fully involved in all aspects of the investigation. In addition to the intrinsic scientific merits and broader impact, the investigation is an ideal tool for the training of the next generation scientists.
As part of the MARE collaboration to measure the mass of the neutrino with cryogenic mocrocalorimeters, by studying the electron capture decay of Ho-163. Our effort has focused on three major tasks: 1) Developing an acquisition and analysis system for the experiment. 2) Investigating the sensitivity of the experiment through realistic MonteCarlo simulations, in particular, focusing on the effect of double pulses. 3) Investigating the properties of the detectors absorbers once the radioactive source has been implanted into them. A data analysis and acquisition, focused on the requirement of the MARE effect was developed and delivered to our collaborators at the University of Genoa, in Italy. The system has been used for data acquisition from TES detectors for the MARE experiment. The system has also been used, together with MC simulations, to evaluate the efficiency of current algorithms in detecting pileup, and a new algorithm has been developed. Unidentified double pulses are the major limitation to the experiment and, with our investigation, we investigated the limits of the data analysis system. Finally, the properties of gold films implanted with non-radioactive holmium have been investigated. Our results show that the thermal properties of the films have not changed, paving the way to future experiments where the radioactive holmium is implanted in the gold absorber of a microcalorimeter.
