The HOLMES project aims to directly measure the electron neutrino mass using the electron capture decay (EC) of 163Ho down to the eV scale. It will perform a precise measurement of the end-point of the 163Ho calorimetric energy spectrum to search for the deformation caused by a finite electron neutrino mass. The choice of 163Ho as source is driven by the very low Q-value of the EC reaction (around 2.8 keV), which allows for a high sensitivity while keeping the overall activities to reasonable value (O(102)Hz/detector), thus reducing the pile-up probability. A large array made of thousands of Transition Edge Sensor based micro-calorimeters will be used for a calorimetric measurement of the EC 163Ho spectrum. The calorimetric approach, with the source embedded inside the detector, eliminates systematic uncertainties arising from the use of an external beta-source, and minimizes the effect of the atomic de-excitation process uncertainties. The commissioning of the first implanted sub-Array is scheduled for the end of 2017. It will provide useful data about the EC decay of 163Ho together with a first limit on neutrino mass. In this paper the current status of the main tasks will be summarized: The TES array design and engineering, the isotope preparation and embedding, and the development of a high speed multiplexed SQUID read-out system for the data acquisition.
Gerone, M., Alpert, B., Becker, D., Bennett, D., Biasotti, M., Ceriale, V., et al. (2020). Probing the absolute neutrino mass scale with the 163Ho: The HOLMES project. Intervento presentato a: 15th International Conference on Topics in Astroparticle and Underground Physics, TAUP 2017, Canada [10.1088/1742-6596/1342/1/012092].
Probing the absolute neutrino mass scale with the 163Ho: The HOLMES project
Faverzani M.;Ferri E.;Gatti F.;Giachero A.;Orlando A.;Pessina G.;Puiu A.;Ragazzi S.;Vale L.
2020
Abstract
The HOLMES project aims to directly measure the electron neutrino mass using the electron capture decay (EC) of 163Ho down to the eV scale. It will perform a precise measurement of the end-point of the 163Ho calorimetric energy spectrum to search for the deformation caused by a finite electron neutrino mass. The choice of 163Ho as source is driven by the very low Q-value of the EC reaction (around 2.8 keV), which allows for a high sensitivity while keeping the overall activities to reasonable value (O(102)Hz/detector), thus reducing the pile-up probability. A large array made of thousands of Transition Edge Sensor based micro-calorimeters will be used for a calorimetric measurement of the EC 163Ho spectrum. The calorimetric approach, with the source embedded inside the detector, eliminates systematic uncertainties arising from the use of an external beta-source, and minimizes the effect of the atomic de-excitation process uncertainties. The commissioning of the first implanted sub-Array is scheduled for the end of 2017. It will provide useful data about the EC decay of 163Ho together with a first limit on neutrino mass. In this paper the current status of the main tasks will be summarized: The TES array design and engineering, the isotope preparation and embedding, and the development of a high speed multiplexed SQUID read-out system for the data acquisition.
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