679 research outputs found

    Pairing-excitation versus intruder states in 68Ni and 90Zr

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    A discussion on the nature of the 0+ states in 68Ni (Z=28, N=40) is presented and a comparison is made with its valence counterpart 90Zr (Z=40, N=50). Evidence is given for a 0+ proton intruder state at only ~2.2 MeV excitation energy in 68Ni, while the analogous neutron intruder states in 90Zr reside at 4126 keV and 5441 keV. The application of a shell-model description of 0+ intruder states reveals that many pair-scattered neutrons across N=40 have to be involved to explain the low excitation energy of the proton-intruder configuration in 68Ni.Comment: 10 pages, 2 figures, 1 tabl

    Abrupt changes in alpha decay systematics as a manifestation of collective nuclear modes

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    An abrupt change in α\alpha decay systematics around the N=126 neutron shell closure is discussed. It is explained as a sudden hindrance of the clustering of the nucleons that eventually form the α\alpha particle. This is because the clustering induced by the pairing mode acting upon the four nucleons is inhibited if the configuration space does not allow a proper manifestation of the pairing collectivity.Comment: 6 pages, 3 figures, submitted to Phys. Rev. C, a few new references adde

    Promoting Stakeholder Participation in a Learning-Based Monitoring and Evaluation Framework

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    This research analysed monitoring and evaluation activities based on the Outcome Mapping methodology within the Zimbabwe Secondary Teacher Training Environmental Education Project (St2eep), an education for sustainability initiative in Zimbabwe. The majority of donorfunded environmental education programmes use conventional monitoring and evaluation approaches based on the logical frameworks (logframe) that guide the programme designs and management. Although research indicates significant problems with the implementation of these approaches, there are only a few documented examples of experiences with alternative monitoring and evaluation frameworks. The case of St2eep allowed us to compare three years of experiences with monitoring and evaluation based on the logframe, with two years of monitoring and evaluation based on Outcome Mapping. We evaluate how the project team and the donor organisation, VVOB (the Flemish Office for Development, Cooperation and Technical Assistance), have perceived the performance of Outcome Mapping with regards to the two main aims of monitoring and evaluation activities: accountability and learning. This is complemented with an analysis of monitoring documentation. The project team refers to the collaborative nature of monitoring and evaluation in St2eep, the principles of self-assessment and peer-assessment, combined with public recognition for project successes, as the key factors supporting learning and accountability through monitoring and evaluation in St2eep. The Outcome Mapping-based monitoring and evaluation system is shown to enhance ownership and participation of local stakeholders in the project’s monitoring and evaluation system

    A Case of Urogenital Human Schistosomiasis from a Non-endemic Area

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    © 2015 Calvo-Cano et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article

    In-gas-cell laser ionization spectroscopy in the vicinity of 100Sn: Magnetic moments and mean-square charge radii of N=50-54 Ag

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    In-gas-cell laser ionization spectroscopy studies on the neutron deficient 97-101Ag isotopes have been performed with the LISOL setup. Magnetic dipole moments and mean-square charge radii have been determined for the first time with the exception of 101Ag, which was found in good agreement with previous experimental values. The reported results allow tentatively assigning the spin of 97,99Ag to 9/2 and confirming the presence of an isomeric state in these two isotopes, whose collapsed hyperfine structure suggests a spin of 1/2 . The effect of the N=50 shell closure is not only manifested in the magnetic moments but also in the evolution of the mean-square charge radii of the isotopes investigated, in accordance with the spherical droplet model predictions

    beta-decay study of Cu-77

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    A beta-decay study of Cu-77 has been performed at the ISOLDE mass separator with the aim to deduce its beta-decay properties and to obtain spectroscopic information on Zn-77. Neutron-rich copper isotopes were produced by means of proton- or neutron-induced fission reactions on U-238. After the production, Cu-77 was selectively laser ionized, mass separated and sent to different detection systems where beta-gamma and beta-n coincidence data were collected. We report on the deduced half-live, decay scheme, and possible spin assignment of 77Cu

    Low-energy Coulomb excitation of 62^{62}Fe and 62^{62}Mn following in-beam decay of 62^{62}Mn

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    Sub-barrier Coulomb-excitation was performed on a mixed beam of 62^{62}Mn and 62^{62}Fe, following in-trap ÎČ−\beta^{-} decay of 62^{62}Mn at REX-ISOLDE, CERN. The trapping and charge breeding times were varied in order to alter the composition of the beam, which was measured by means of an ionisation chamber at the zero-angle position of the Miniball array. A new transition was observed at 418~keV, which has been tentatively associated to a (2+,3+)→1g.s.+(2^{+},3^{+})\rightarrow1^{+}_{g.s.} transition. This fixes the relative positions of the ÎČ\beta-decaying 4+4^{+} and 1+1^{+} states in 62^{62}Mn for the first time. Population of the 21+2^{+}_{1} state was observed in 62^{62}Fe and the cross-section determined by normalisation to the 109^{109}Ag target excitation, confirming the B(E2)B(E2) value measured in recoil-distance lifetime experiments.Comment: 9 pages, 10 figure

    Beta-delayed deuteron emission from 11Li: decay of the halo

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    The deuteron-emission channel in the beta-decay of the halo-nucleus 11Li was measured at the ISAC facility at TRIUMF by implanting post-accelerated 11Li ions into a segmented silicon detector. The events of interest were identified by correlating the decays of 11Li with those of the daughter nuclei. This method allowed the energy spectrum of the emitted deuterons to be extracted, free from contributions from other channels, and a precise value for the branching ratio B_d = 1.30(13) x 10-4 to be deduced for E(c.m.) > 200 keV. The results provide the first unambiguous experimental evidence that the decay takes place essentially in the halo of 11Li, and that it proceeds mainly to the 9Li + d continuum, opening up a new means to study of the halo wave function of 11Li.Comment: 4 pages, 3 figure
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