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High-spin states in the N = 128 nucleus 218Th have been investigated following fusion–evaporation reactions, using the recoil-decay tagging technique. Due to the short-lived nature of the ground state of 218Th prompt γ rays have been correlated with the α decay of the daughter nucleus 214Ra. The level scheme representing the decay of excited states has been extended to (16+) with the observation of six previously unreported transitions. The observations are compared with the results of shell model calculations and within the context of the systematics of neighbouring nuclei. [ABSTRACT FROM AUTHOR]

The excited states of 201At were studied and an isomeric 29/2+ state [T1/2 = 3.39(9)μs] was identified by using a fusion-evaporation reaction, a gas-filled recoil separator, and recoil gating techniques. The 29/2+ state is suggested to originate from the π(h9/2) ⊗ |200Po;11-) configuration, and it decays through the 269- and 339-keV E2- and E3-type transitions, respectively. Moreover, a cascade of magnetic dipole transitions that is suggested to originate from a shears band was observed by using recoil-gated γ-γ(-γ) coincidence techniques. [ABSTRACT FROM AUTHOR]

Using fusion-evaporation reactions, a gas-filled recoil separator, and recoil-electron and recoil-electron-α tagging techniques, a new isomeric 1/2+ state [T1/2=45(3)ms] in 201At is identified, and an earlier reported corresponding state [T1/2=273(9)ms] in 199At is confirmed. The 1/2+ state is suggested to originate from an intruder π(s1/2)-1 configuration. In addition, nuclear structure of states below and above this1/2+ state are studied in both nuclei. The isomer decays through a cascade of an E3 transition followed by a mixed M1/E2 transition to the 9/2- ground state, and it is interpreted to be fed from nearly spherical 3/2+ and 5/2+ states originating from π(d3/2)-1 and π(d5/2)-1 configurations, respectively. [ABSTRACT FROM AUTHOR]

We report the first observation of the 108Xe→104Te→100Sn α-decay chain. The α emitters, 108Xe [Eα=4.4(2)  MeV, T1/2=58+106-23 μs] and 104Te [Eα=4.9(2)  MeV, T1/2<18  ns], decaying into doubly magic 100Sn were produced using a fusion-evaporation reaction 54Fe(58Ni,4n)108Xe, and identified with a recoil mass separator and an implantation-decay correlation technique. This is the first time α radioactivity has been observed to a heavy self-conjugate nucleus. A previous benchmark for study of this fundamental decay mode has been the decay of 212Po into doubly magic 208Pb. Enhanced proton-neutron interactions in the N=Z parent nuclei may result in superallowed α decays with reduced α-decay widths significantly greater than that for 212Po. From the decay chain, we deduce that the α-reduced width for 108Xe or 104Te is more than a factor of 5 larger than that for 212Po. [ABSTRACT FROM AUTHOR]

Using fusion-evaporation reactions, a gas-filled recoil separator, recoil-gating technique and recoil-isomer decay tagging technique we have extended the level scheme of 203At(N=118) significantly. We have observed an isomeric [τ=14.1(3)μs] state with a spin and parity of 29/2+. The isomeric state is suggested to originate from the π(h9/2)⊗∣∣202Po;11-⟩ coupling, and it is depopulated through 286 keV E2 and 366 keV E3 transitions. In addition, we have observed a cascade of magnetic-dipole transitions which is suggested to be generated by the shears mechanism. [ABSTRACT FROM AUTHOR]

This letter reports on the first observation of an octupole band in the neutron-deficient (N = Z + 2) nucleus 110Xe. The 110Xe nuclei were produced via the 54Fe(58Ni,2n) fusion-evaporation reaction. The emitted γ rays were detected using the jurogam 3 γ -ray spectrometer, while the fusion-evaporation residues were separated with the MARA separator at the Accelerator Laboratory of the University of Jyväskylä, Finland. The experimental observation of the low-lying 3− and 5− states and inter-band E1 transitions between the ground-state band and the octupole band proves the importance of octupole correlations in this region. These new experimental data combined with theoretical calculations using the symmetry-conserving configuration-mixing method, based on a Gogny energy density functional, have been interpreted as an evidence of enhanced octupole correlations in neutron-deficient xenon isotopes. [ABSTRACT FROM AUTHOR]

The radioactivity of 76 160 Os 84 and 74 156 W 82 that lie at the two-proton drip line has been measured in an experiment performed at the Accelerator Laboratory of the University of Jyväskylä. The 160Os nuclei were produced using fusion-evaporation reactions induced by a beam of 310 MeV 58Ni ions bombarding a 106Cd target. The 160Os ions were separated in flight using the recoil separator MARA and implanted into a double-sided silicon strip detector, which was used to measure their decays. The α decays of the ground state of 160Os (E α = 7092(15) keV, t 1 / 2 = 97 − 32 + 97 μs) and its isomeric state (E α = 8890(10) keV, t 1 / 2 = 41 − 9 + 15 μs) were measured, allowing the excitation energy of the isomer to be determined as 1844(18) keV. These α -decay properties and the excitation energy of the isomer are compared with systematics. The α decays were correlated with subsequent decays to investigate the β decays of the ground state of 156W, revealing that unlike its isotones, both low-lying isomers were populated in its daughter nuclide, 156Ta. An improved value for the half-life of the proton-decaying high-spin isomeric state in 73 156 Ta 83 of 333 − 22 + 25 ms was obtained in a separate experiment using the same experimental systems with a 102Pd target. This result was employed to improve the precision of the half-life determined for 156W, which was measured as 157 − 34 + 57 ms. [ABSTRACT FROM AUTHOR]

Excited states in the T z = 0 , − 1 nuclei 62Ga and 62Ge were populated in direct reactions of relativistic radioactive ion beams at the RIBF. Coincident γ rays were measured with the DALI2+ array and uniquely assigned to the A = 62 isobars. In addition, 62Ge was also studied independently at JYFL-ACCLAB using the 24Mg(40Ca,2 n)62Ge fusion-evaporation reaction. The first excited T = 1 , J π = 2 + states in 62Ga and 62Ge were identified at 979 (1) and 965 (1) keV, respectively, resolving discrepant interpretations in the literature. States beyond the first 2 + state in 62Ge were also identified for the first time in the present work. The results are compared with shell-model calculations in the fp model space. Mirror and triplet energy differences are analyzed in terms of individual charge-symmetry and charge-independence breaking contributions. The MED results confirm the shrinkage of the p -orbits' radii when they are occupied by at least one nucleon on average. [ABSTRACT FROM AUTHOR]