Search

Second-order processes in physics is a research topic focusing attention from several fields worldwide including, for example, non-linear quantum electrodynamics with high-power lasers, neutrinoless double-β decay, and stimulated atomic two-photon transitions. For the electromagnetic nuclear interaction, the observation of the competitive double-γ decay from 137mBa has opened up the nuclear structure field for detailed investigation of second-order processes through the manifestation of off-diagonal nuclear polarisability. Here, we confirm this observation with an 8.7σ significance, and an improved value on the double-photon versus single-photon branching ratio as 2.62 × 10-6(30). Our results, however, contradict the conclusions from the original experiment, where the decay was interpreted to be dominated by a quadrupole-quadrupole component. Here, we find a substantial enhancement in the energy distribution consistent with a dominating octupole-dipole character and a rather small quadrupole-quadrupole component in the decay, hindered due to an evolution of the internal nuclear structure. The implied strongly hindered double-photon branching in 137mBa opens up the possibility of the double-photon branching as a feasible tool for nuclear-structure studies on off-diagonal polarisability in nuclei where this hindrance is not present. ispartof: NATURE COMMUNICATIONS vol:11 issue:1 ispartof: location:England status: published

Excited states have been identified in the very neutron-deficient N=Z+3 nucleus Xe111 for the first time, using the Ni58(Ni58,αn) heavy-ion fusion-evaporation reaction. γ-ray transitions have been unambiguously assigned to Xe111 by correlation with the characteristic Xe111→Te107→Sn103 α-decay chain using the method of recoil-decay tagging. Inspection of γγ-coincidence data has shown that five of the transitions form a rotational-like sequence. Excitation-energy systematics suggest that the sequence could be the favored signature partner of a band built on an h11/2 neutron. Aligned angular momenta of states in the band have been compared to analogous bands in neighboring xenon isotopes. The aligned angular momenta for the Xe111 band are constant over the range of observed rotational frequencies, suggesting that the first π(h11/2)2 alignment is either delayed or absent. It is speculated that the alignment of h11/2 protons in the presence of neutrons in near-identical h11/2 orbitals may be affected by neutron-proton interactions or by the onset of octupole correlations.

Second-order processes in physics is a research topic focusing attention from several fields worldwide including, for example, non-linear quantum electrodynamics with high-power lasers, neutrinoless double-$��$ decay, and stimulated atomic two-photon transitions. For the electromagnetic nuclear interaction, the observation of the competitive double-$��$ decay from $^{137\mathrm{m}}$Ba has opened up the nuclear structure field for detailed investigation of second-order processes through the manifestation of off-diagonal nuclear polarizability. Here we confirm this observation with an $8.7��$ significance, and an improved value on the double-photon versus single-photon branching ratio as $2.62\times10^{-6}(30)$. Our results, however, contradict the conclusions from the original experiment, where the decay was interpreted to be dominated by a quadrupole-quadrupole component. Here, we find a substantial enhancement in the energy distribution consistent with a dominating octupole-dipole character and a rather small quadrupole-quadrupole element in the decay, hindered due to an evolution of the internal nuclear structure. The implied strongly hindered double-photon branching in $^{137\mathrm{m}}$Ba opens up the possibility of the double-photon branching as a feasible tool for nuclear-structure studies on off-diagonal polarizability in nuclei where this hindrance is not present., 12 pages, 5 figures, 2 tabels

Excited states have been identified in the very neutron-deficient N = Z + 3 nucleus 111Xe for the first time, using the 58Ni(58Ni, αn) heavy-ion fusion-evaporation reaction. γ -ray transitions have been unambiguously assigned to 111Xe by correlation with the characteristic 111Xe → 107Te → 103Sn α-decay chain using the method of recoil-decay tagging. Inspection of γ γ -coincidence data has shown that five of the transitions form a rotational-like sequence. Excitation-energy systematics suggest that the sequence could be the favored signature partner of a band built on an h11/2 neutron. Aligned angular momenta of states in the band have been compared to analogous bands in neighboring xenon isotopes. The aligned angular momenta for the 111Xe band are constant over the range of observed rotational frequencies, suggesting that the first π(h11/2 ) 2 alignment is either delayed or absent. It is speculated that the alignment of h11/2 protons in the presence of neutrons in near-identical h11/2 orbitals may be affected by neutron-proton interactions or by the onset of octupole correlations. peerReviewed

The neutron-deficient nucleus Hg-173 has been studied following fusion-evaporation reactions. The observation of the decay of excited states via gamma radiation are reported for the first time and a tentative level scheme is proposed. The proposed level scheme is discussed within the context of the systematics of neighboring neutron-deficient Hg nuclei. In addition to the gamma-ray spectroscopy, the alpha decay of this nucleus has been measured yielding superior precision to earlier measurements.

The neutron-deficient nucleus 173Hg has been studied following fusion-evaporation reactions. The observation of the decay of excited states via γ radiation are reported for the first time and a tentative level scheme is proposed. The proposed level scheme is discussed within the context of the systematics of neighboring neutron-deficient Hg nuclei. In addition to the γ -ray spectroscopy, the α decay of this nucleus has been measured yielding superior precision to earlier measurements. peerReviewed

The neutron-deficient nucleus Hg-173 has been studied following fusion-evaporation reactions. The observation of the decay of excited states via gamma radiation are reported for the first time and a tentative level scheme is proposed. The proposed level scheme is discussed within the context of the systematics of neighboring neutron-deficient Hg nuclei. In addition to the gamma-ray spectroscopy, the alpha decay of this nucleus has been measured yielding superior precision to earlier measurements.