544 research outputs found
Spectroscopy of Sc and ab initio calculations of strengths
The GRIFFIN spectrometer at TRIUMF-ISAC has been used to study excited states
and transitions in Sc following the -decay of Ca.
Branching ratios were determined from the measured -ray intensities,
and angular correlations of rays have been used to firmly assign the
spins of excited states. The presence of an isomeric state that decays by an
transition with a strength of 13.6(7)\,W.u. has been confirmed. We
compare with the first {\it ab initio} calculations of ) strengths in
light and medium-mass nuclei from the valence-space in-medium similarity
renormalization group approach, using consistently derived effective
Hamiltonians and operator. The experimental data are well reproduced for
isoscalar transitions when using bare -factors, but the strength of
isovector transitions are found to be underestimated by an order of
magnitude
Core excitations across the neutron shell gap in ²⁰⁷Tl
The single closed-neutron-shell, one proton-hole nucleus 207Tl was populated in deep-inelastic collisions of a 208Pb beam with a 208Pb target. The yrast and near-yrast level scheme has been established up to high excitation energy, comprising an octupol
Octupole strength in the neutron-rich calcium isotopes
Low-lying excited states of the neutron-rich calcium isotopes Ca
have been studied via -ray spectroscopy following inverse-kinematics
proton scattering on a liquid hydrogen target using the GRETINA -ray
tracking array. The energies and strengths of the octupole states in these
isotopes are remarkably constant, indicating that these states are dominated by
proton excitations.Comment: 15 pages, 3 figure
Spectroscopy of Ti and the systematic behavior of low energy octupole states in Ca and Ti isotopes
Excited states of the nucleus Ti have been studied, via both
inverse-kinematics proton scattering and one-neutron knockout from Ti by
a liquid hydrogen target, using the GRETINA -ray tracking array.
Inelastic proton-scattering cross sections and deformation lengths have been
determined. A low-lying octupole state has been tentatively identified in
Ti for the first time. A comparison of results on low-energy
octupole states in the neutron-rich Ca and Ti isotopes with the results of
Random Phase Approximation calculations demonstrates that the observed
systematic behavior of these states is unexpected.Comment: 7 pages, 8 figure
Spectroscopy of Ti and the systematic behavior of low energy octupole states in Ca and Ti isotopes
Excited states of the nucleus Ti have been studied, via both
inverse-kinematics proton scattering and one-neutron knockout from Ti by
a liquid hydrogen target, using the GRETINA -ray tracking array.
Inelastic proton-scattering cross sections and deformation lengths have been
determined. A low-lying octupole state has been tentatively identified in
Ti for the first time. A comparison of results on low-energy
octupole states in the neutron-rich Ca and Ti isotopes with the results of
Random Phase Approximation calculations demonstrates that the observed
systematic behavior of these states is unexpected.Comment: 7 pages, 8 figure
Population of high-spin isomeric states following fragmentation of 238 U
Isomeric ratios have been determined for 23 metastable states identified in A?200 nuclei from Pt to Rn near the valley of stability following fragmentation of 238U. This includes high-spin states with angular momenta ranging from (39/2) to 25. The experimental results are discussed together with those of similar experiments performed in this mass region. Isomeric ratios are compared with theoretical predictions where the angular momentum of the fragment arises purely due to the angular momentum of nucleons removed from the projectile. The theoretical yield of low-spin states is generally overestimated. In these cases the assumption of 100% feeding of the isomer may require modification. However, the yield of high-spin isomeric states [Im ? (39/2)] is significantly underestimated and highlights the requirement for a more complete theoretical framework in relation to the generation of fragment angular momentum. The enhanced population of high-spin states reported here is advantageous to future studies involving isomeric beams at fragmentation facilities such as the Rikagaku Kenkyusho RI Beam Factory (Japan) and next-generation facilities at the Facility for Antiproton and Ion Research (Germany) and Facility for Rare Isotope Beams (USA). � 2013 American Physical Society
Total Absorption Spectroscopy Study of Rb Decay: A Major Contributor to Reactor Antineutrino Spectrum Shape
The antineutrino spectra measured in recent experiments at reactors are
inconsistent with calculations based on the conversion of integral beta spectra
recorded at the ILL reactor. Rb makes the dominant contribution to the
reactor spectrum in the 5-8 MeV range but its decay properties are in question.
We have studied Rb decay with total absorption spectroscopy. Previously
unobserved beta feeding was seen in the 4.5-5.5 region and the GS to GS feeding
was found to be 87.5(25)%. The impact on the reactor antineutrino spectra
calculated with the summation method is shown and discussed.Comment: 6 pages, 3 figure
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