19 research outputs found
Improved precision on the experimental E0 decay branching ratio of the Hoyle state
Stellar carbon synthesis occurs exclusively via the process, in
which three particles fuse to form C in the excited Hoyle
state, followed by electromagnetic decay to the ground state. The Hoyle state
is above the threshold, and the rate of stellar carbon production
depends on the radiative width of this state. The radiative width cannot be
measured directly, and must instead be deduced by combining three separately
measured quantities. One of these quantities is the decay branching ratio
of the Hoyle state, and the current \% uncertainty on the radiative width
stems mainly from the uncertainty on this ratio. The branching ratio was
deduced from a series of pair conversion measurements of the and
transitions depopulating the Hoyle state and state in C,
respectively. The excited states were populated by the C
reaction at 10.5 MeV beam energy, and the pairs were detected with the
electron-positron pair spectrometer, Super-e, at the Australian National
University. The deduced branching ratio required knowledge of the proton
population of the two states, as well as the alignment of the state in
the reaction. For this purpose, proton scattering and -ray angular
distribution experiments were also performed. An branching ratio of
was deduced in the current work,
and an adopted value of is
recommended based on a weighted average of previous literature values and the
new result. The new recommended value for the branching ratio is about 14%
larger than the previous adopted value of
, while the uncertainty has been
reduced from 9% to 5%.Comment: Accepted for publication as a Regular Article in Phys. Rev. C on July
29 202
E0 transition strength in stable Ni isotopes
Excited states in 58,60,62Ni were populated via inelastic proton scattering at the Australian National University as well as via inelastic neutron scattering at the University of Kentucky Accelerator Laboratory. The Super-e electron spectrometer and the CAESAR Compton-suppressed HPGe array were used in complementary experiments to measure conversion coefficients and δ(E2/M1) mixing ratios, respectively, for a number of 2+→2+ transitions. The data obtained were combined with lifetimes and branching ratios to determine E0,M1, and E2 transition strengths between 2+ states. The E0 transition strengths between 0+ states were measured using internal conversion electron spectroscopy and compare well to previous results from internal pair formation spectroscopy. The E0transition strengths between the lowest-lying 2+ states were found to be consistently large for the isotopes studied
Recoil in vacuum for Te ions: Calibration, models, and applications to radioactive-beam g-factor measurements
In the light of new g factor results for the stable isotopes between 122Te and 130Te, the calibration and modeling of the recoil-in-vacuum (RIV) interaction for Te ions is reexamined, and the recent radioactive-beam g factor measurement on 132Te by the RIV technique is reevaluated. The implications for further RIV g-factor measurements in the 132Sn region are discussed. © 2007 The American Physical Society
Calibration of Recoil-In-Vacuum attenuations from first principles: comparison with recent experimental data on Fe isotopes
Backbending in <sup>180</sup>W: a t-band crossing
A Fermi-aligned (i 13 2)2 rotational band, with K≈8, has been observed in an even-even nucleus, 180W. Its structure corresponds to a t-band in the tilted-cranking representation. It crosses the ground-state band at I = 16 h {combining short stroke overlay}, giving rise to backbending in the yrast sequence. Contrary to the usual interpretation, backbending in this case is not caused by the s-band. Comparison is made with other possible t-band crossings in the A ≈ 180 region. © 1993
Backbending in <sup>180</sup>W: a t-band crossing
A Fermi-aligned (i 13 2)2 rotational band, with K≈8, has been observed in an even-even nucleus, 180W. Its structure corresponds to a t-band in the tilted-cranking representation. It crosses the ground-state band at I = 16 h {combining short stroke overlay}, giving rise to backbending in the yrast sequence. Contrary to the usual interpretation, backbending in this case is not caused by the s-band. Comparison is made with other possible t-band crossings in the A ≈ 180 region. © 1993
La-135 as an Auger-electron emitter for targeted internal radiotherapy
135La has favorable nuclear and chemical properties for Auger-based targeted internal radiotherapy. Here we present detailed investigations of the production, emissions, and dosimetry related to 135La therapy. 135La was produced by 16.5 MeV proton irradiation of metallic natBa on a medical cyclotron, and was isolated and purified by trap-and-release on weak cation-exchange resin. The average production rate was 407  ±  19 MBq µA−1 (saturation activity), and the radionuclidic purity was 98% at 20 h post irradiation. Chemical separation recovered  >  98 % of the 135La with an effective molar activity of 70  ±  20 GBq µmol−1. To better assess cellular and organ dosimetry of this nuclide, we have calculated the x-ray and Auger emission spectra using a Monte Carlo model accounting for effects of multiple vacancies during the Auger cascade. The generated Auger spectrum was used to calculate cellular S-factors. 135La was produced with high specific activity, reactivity, radionuclidic purity, and yield. The emission spectrum and the dosimetry are favorable for internal radionuclide therapy
La-135 as an Auger-electron emitter for targeted internal radiotherapy
135La has favorable nuclear and chemical properties for Auger-based targeted internal radiotherapy. Here we present detailed investigations of the production, emissions, and dosimetry related to 135La therapy. 135La was produced by 16.5 MeV proton irradiation of metallic natBa on a medical cyclotron, and was isolated and purified by trap-and-release on weak cation-exchange resin. The average production rate was 407  ±  19 MBq µA−1 (saturation activity), and the radionuclidic purity was 98% at 20 h post irradiation. Chemical separation recovered  >  98 % of the 135La with an effective molar activity of 70  ±  20 GBq µmol−1. To better assess cellular and organ dosimetry of this nuclide, we have calculated the x-ray and Auger emission spectra using a Monte Carlo model accounting for effects of multiple vacancies during the Auger cascade. The generated Auger spectrum was used to calculate cellular S-factors. 135La was produced with high specific activity, reactivity, radionuclidic purity, and yield. The emission spectrum and the dosimetry are favorable for internal radionuclide therapy