Speaker
Description
A low-background measurement of hafnium foil using a modified ultra-low-background high purity detector with optimized sample-to-detector geometry was performed at Laboratori Nazionale del Gran Sasso. Radiopurity of the stock Hf foil was studied in detail, in addition to an analysis of data collected over 310 day to search for rare processes that can occur in natural Hf isotopes. Firstly, leading limits on alpha decays of all natural Hf isotopes to the first excited state of the daughter nuclides were established in the range of 10$^{16}$–10$^{19}$ a (90% C.L.). Secondly, a search for modes of double electron capture and electron capture with positron emission in $^{174}$Hf was performed, yielding half-life limits 10$^{15}$–10$^{18}$ a (90% C.L.). Lastly, novel dark matter-induced nuclear excitations in hafnium isotopes were investigated. For dark matter with 1 TeV/c$^{2}$ mass, leading limits on the inelastic dark matter–nucleon cross section are set for mass splitting’s in the range 430 keV < δMχ < 465 keV.
