Qβ-measurements with a total absorption detector composed of through-hole HPGe detector and anti-Compton BGO detector

A total absorption detector, which is composed of a through-hole type HPGe detector coupled with a surrounding annular anti-Compton BGO detector, has been developed for β−-decay energy (Qβ) measurements of nuclei far off from the β-stability line. This detector can measure radiations with an almost 4π solid angle by putting radioactive sources in the middle of the HPGe detector and also can suppress the scattered photons with the anti-Compton BGO scintillation detector. The systematic uncertainty was determined to be 30 keV by measuring 19 nuclei having Qβs between 3 and 8 MeV by means of conventional square-root plot analysis. The Qβ's of mass-separated fission products 147La and 148La were successfully determined to be 5366(40) and 7732(70) keV, respectively.