The HOLMES experiment aims to directly measure the ν mass with a calorimetric approach. The choice of 163Ho isotope as source is driven by the very low decay Q-value (∼ 2.8 keV), which allows for high sensitivity with low activities (O(102)Hz/detector), thus reducing the pile-up probability. 163Ho will be produced by neutron irradiation of 162Er2O3 then chemically separated; anyway, traces of others isotopes and contaminants will be still present. In particular 166mHo has a beta decay (τ∼1200y) which can induce background below 5 keV. The removal of the contaminants is critical so a dedicated system has been set up. It is designed to achieve an optimal mass separation @ 163 a.m.u. and consists of two main components: an evaporation chamber and an ion implanter. The first item is used to reduce Ho in metallic form providing a target for the ion implanter source. The implanter is made by the sputter source, an acceleration section, a magnetic dipole, a x–y scanning stage and a focusing electrostatic triplet. In this contribution we will describe the procedures for the Holmium “distillation” process and the status of the machine commissioning.
De Gerone, M., Biasotti, M., Ceriale, V., Dressler, R., Faverzani, M., Ferri, E., et al. (2019). 163Ho distillation and implantation for the HOLMES experiment. NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH. SECTION A, ACCELERATORS, SPECTROMETERS, DETECTORS AND ASSOCIATED EQUIPMENT, 936, 220-221 [10.1016/j.nima.2018.10.104].
163Ho distillation and implantation for the HOLMES experiment
Faverzani, M.;Ferri, E.;Gatti, F.;Giachero, A.;Nucciotti, A.;Orlando, A.;Puiu, A.;
2019
Abstract
The HOLMES experiment aims to directly measure the ν mass with a calorimetric approach. The choice of 163Ho isotope as source is driven by the very low decay Q-value (∼ 2.8 keV), which allows for high sensitivity with low activities (O(102)Hz/detector), thus reducing the pile-up probability. 163Ho will be produced by neutron irradiation of 162Er2O3 then chemically separated; anyway, traces of others isotopes and contaminants will be still present. In particular 166mHo has a beta decay (τ∼1200y) which can induce background below 5 keV. The removal of the contaminants is critical so a dedicated system has been set up. It is designed to achieve an optimal mass separation @ 163 a.m.u. and consists of two main components: an evaporation chamber and an ion implanter. The first item is used to reduce Ho in metallic form providing a target for the ion implanter source. The implanter is made by the sputter source, an acceleration section, a magnetic dipole, a x–y scanning stage and a focusing electrostatic triplet. In this contribution we will describe the procedures for the Holmium “distillation” process and the status of the machine commissioning.
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