Beta decay energies and strength function of neutron rich isotopes in the A = 91-100 region

A solid-state DE-E telescope beta spectrometer has been built and used to study beta-minus spectra. The system consists of a 15 mm x 500 mm$ sp2$ hyperpure germanium (HPGe) E-detector and a 300 $ mu$m x 200 mm$ sp2$ Si DE-detector with a special "keyhole" design.The response function of the system has been determined experimentally using mono-energetic electron beams with incident energies ranging from 1 to 12 MeV.The beta endpoint energies of 25 nuclei, namely, $ sp{32}$P, $ sp{88}$Rb, $ sp{91-99}$Rb, $ sp{91-96}$Sr, $ sp{99-100}$Sr, $ sp{92-96}$Y and $ sp{100}$Y have been measured. The Q-beta values and mass excesses for A = 91-100 have been determined. The results for $ sp{99}$Rb, $ sp{99-100}$Sr and $ sp{100}$Y have been obtained for the first time.The beta strength functions for odd mass Rb isotopes, namely $ sp{91-99}$Rb have been measured for the first time from direct beta spectroscopy with a solid-state telescope system. The experimental results have been compared to calculations using the Brown-Bolsterli (B-B) model