Search

International audience; Five new 2+ levels have been established in the semimagic Po210 nucleus from a Pb208(C12,Be10) two-proton transfer experiment, performed at energies close to the Coulomb barrier at JAEA Tokai. A setup combining Ge, LaBr3, and Si telescopes was used to detect both in-beam γ rays and ejectile residues. The new 2+ states have been established by means of the transitions toward the 0+ ground state which are present in the γ spectra produced by properly selecting the excitation energy in Po210 after kinematical reconstruction. (f7/2)2, h9/2⊗f5/2, (i13/2)2, f7/2⊗p3/2, and f7/2⊗f5/2 two-proton configurations are assigned to these states. In addition, a new 3− level has also been established in this nucleus, very likely originating from the f7/2⊗i13/2 configuration. Shell-model calculations strongly support these assignments.

International audience; A search for superallowed α decay of N=Z nuclei Te104 and Xe108 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-sensitive photomultiplier tube (PSPMT) was implemented for the first time in a radioactive decay experiment. Residues from the fusion-evaporation reaction Ni58+Fe54→Xe*112 were separated by the JAEA Recoil Mass Separator (RMS) and implanted into the YAP:Ce crystal. α decays of neutron-deficient tellurium isotopes were identified and proton emission of I109 was observed. The α-decay chain Xe109→Te105→Sn101 was recorded with a time interval of 960 ns between two α pulses. Position localization in the crystal for decays and ions in the energy range from hundreds of keV to 60 MeV was achieved with an accuracy of 0.67 mm, proving that this detector is capable of making temporal and spatial correlations for fast decay events. No conclusive evidence was found for the decay chain Xe108→Te104→Sn100 within 3 days of experiment. However, two events were observed with properties consistent with the reported observation at the Fragment Mass Analyzer (FMA), but with a separation between signals of less than 4 ns. The cross section limit of 130 pb was obtained for production of two events of Xe108, about an order of magnitude below the expectation based on earlier cross section measurements and the hivap fusion-evaporation code.