Observation of the 0+ 2 and γ bands in 98Ru, and shape coexistence in the Ru isotopes

Excited states in 98Ru were investigated using γ-ray spectroscopy following the β-decay of 98Rh, and via the 100Ru(p,t) reaction. Combining the results from the two experiments, two states were revised to have spin-parity of 4+ and subsequently assigned to the 02+ and “γ” bands, respectively. The observed structures in 98Ru are suggested to be deformed and rotational, rather than spherical and vibrational, and fit well into the systematics of these excitations in the Ru isotopes. The 02+ excitation is suggested as a shape coexisting configuration. This observation eliminates some of the last remaining candidates for nearly harmonic vibrational nuclei in the Z≈50 region. Beyond-mean-field calculations are presented that support shape coexistence throughout the Ru isotopes with N=52–62, and suggest a smooth evolution of the shape

A historical overview of the classification, evolution, and dispersion of Leishmania parasites and sandflies

Background The aim of this study is to describe the major evolutionary historical events among Leishmania, sandflies, and the associated animal reservoirs in detail, in accordance with the geographical evolution of the Earth, which has not been previously discussed on a large scale. Methodology and Principal Findings Leishmania and sandfly classification has always been a controversial matter, and the increasing number of species currently described further complicates this issue. Despite several hypotheses on the origin, evolution, and distribution of Leishmania and sandflies in the Old and New World, no consistent agreement exists regarding dissemination of the actors that play roles in leishmaniasis. For this purpose, we present here three centuries of research on sandflies and Leishmania descriptions, as well as a complete description of Leishmania and sandfly fossils and the emergence date of each Leishmania and sandfly group during different geographical periods, from 550 million years ago until now. We discuss critically the different approaches that were used for Leishmana and sandfly classification and their synonymies, proposing an updated classification for each species of Leishmania and sandfly. We update information on the current distribution and dispersion of different species of Leishmania (53), sandflies (more than 800 at genus or subgenus level), and animal reservoirs in each of the following geographical ecozones: Palearctic, Nearctic, Neotropic, Afrotropical, Oriental, Malagasy, and Australian. We propose an updated list of the potential and proven sandfly vectors for each Leishmania species in the Old and New World. Finally, we address a classical question about digenetic Leishmania evolution: which was the first host, a vertebrate or an invertebrate? Conclusions and Significance We propose an updated view of events that have played important roles in the geographical dispersion of sandflies, in relation to both the Leishmania species they transmit and the animal reservoirs of the parasites

High-resolution investigation of the Sb-121(p,t)Sb-119 reaction and quasiparticle-phonon model description

The Sb-121(p,t)Sb-119 reaction has been measured in a high-resolution experiment at an incident energy of 21 MeV. Accurate measurement of the (p,t) reaction angular distributions for the transitions to the levels of Sb-119 allows us to determine energies of 59 levels, 23 of which have been identified for the first time, and to assign the angular momentum transfer values and a well-defined range for the J values. DWBA analysis has been performed in a finite-range approximation, assuming a dineutron cluster pickup mechanism, by using conventional Woods-Saxon potentials for the entrance proton and exit triton channel. The present (p,t) data have been supplemented by microscopic calculations in the framework of the quasiparticle-phonon model, giving a reasonably good description of the experimental fragmentation of the integrated cross sections and the absence of (p,t) strength above 2.9 MeV

High-resolution study of the Sn-116(p,t) reaction and shell model structure of Sn-114

The Sn-116(p, t) Sn-114 reaction has been studied in a high-resolution experiment at an incident proton energy of 26 MeV. Angular distributions for 61 transitions to levels of Sn-114 up to an excitation energy of similar to4.1 MeV have been measured. A distorted-wave Born approximation analysis of experimental angular distributions using conventional Woods-Saxon potentials has been done, allowing,either the confirmation of previous spin and parity values or the assignment of new spin and parity to a large number of Sn-114 states. A shell-model study of Sn-114 has been performed using a realistic effective interaction derived from the CD-Bonn nucleon-nucleon potential. The model space has been truncated to states with seniority up to 4. Comparison between the, experimental and calculated energy spectra for both positive- and negative-parity states shows a quite satisfactory agreement

Shell model and band structures in O 19

We have studied the reaction ( ^7Li, p) on 13C targets at E lab = 44 MeV, populating states in the oxygen isotope 19O . The experiments were performed at the Tandem Laboratory (Maier-Leibniz Laboratorium) using the high-resolution Q3D magnetic spectrometer. States were populated up to an excitation energy of 21MeV, with an overall energy resolution of 45keV. We discuss shell model states and cluster bands related to the rotational bands in the 18O -isotope, using the weak-coupling approach. Similar to 18O , the broken intrinsic reflection symmetry in these states must give rise to rotational bands as parity doublets, so two K = 3/2 bands (parities, + and - are proposed with large moments of inertia. These are discussed in terms of an underlying cluster structure, ( ^14C ⊗ n ⊗ $\alpha$) . An extended molecular binding diagram is proposed which includes the 14C -cluster

Molecular and cluster structures in O 18

We have studied the multi-nucleon transfer reaction C-12(Li-7, p) at E-lab = 44MeV, populating states in the oxygen isotope O-18. The experiments were performed at the Tandem accelerator of the Maier-Leibniz Laboratory in Munich using the high-resolution Q3D magnetic spectrograph. States were populated up to an excitation energy of 21.2MeV with an overall energy resolution of 45keV, and 30 new states of O-18 have been identified. The structure of the rotational bands observed is discussed in terms of cluster bands with the underlying cluster structures: C-14 circle times alpha and C-12 circle times 2n circle times alpha. Because of the broken intrinsic reflection symmetry in these structures the corresponding rotational bands appear as parity doublets

Study of the (133)Ba nucleus with the ((d)over-right-arrow, p) reaction

Excited states in (133)Ba were studied with the (132)Ba((d) over right arrow, p)(133)Ba reaction at 24.0MeV, with a polarized deuteron beam using the Munich magnetic spectrograph Q3D. Many unambiguous spin-parity assignments were made up to an excitation energy of 2.2MeV, which allow a detailed comparison with different theoretical calculations, such as the interacting boson-fermion model and the shell model