Search for α decay of Te104 with a novel recoil-decay scintillation detector

A search for superallowedαdecay ofN=Znuclei104Te and108Xe was carried out using a novel recoil-decay scintillator detector at the tandem accelerator facility at the Japan Atomic Energy Agency (JAEA).Inorganic crystal scintillation material YAP:Ce (yttrium aluminum perovskite) coupled to a position-sensitivephotomultiplier tube (PSPMT) was implemented for the first time in a radioactive decay experiment. Residuesfrom the fusion-evaporation reaction58Ni+54Fe→112Xe∗were separated by the JAEA Recoil Mass Separator(RMS) and implanted into the YAP:Ce crystal.αdecays of neutron-deficient tellurium isotopes were identifiedand proton emission of109I was observed. Theα-decay chain109Xe→105Te→101Sn was recorded with atime interval of 960 ns between twoαpulses. Position localization in the crystal for decays and ions in the energyrange from hundreds of keV to 60 MeV was achieved with an accuracy of 0.67 mm, proving that this detector iscapable of making temporal and spatial correlations for fast decay events. No conclusive evidence was found forthe decay chain108Xe→104Te→100Sn within 3 days of experiment. However, two events were observed withproperties consistent with the reported observation at the Fragment Mass Analyzer (FMA), but with a separationbetween signals of less than 4 ns. The cross section limit of 130 pb was obtained for production of two events of108Xe, about an order of magnitude below the expectation based on earlier cross section measurements and theHIVAPfusion-evaporation code.