267 research outputs found
In-beam fast-timing measurements in 103,105,107Cd
Fast-timing measurements were performed recently in the region of the
medium-mass 103,105,107Cd isotopes, produced in fusion evaporation reactions.
Emitted gamma-rays were detected by eight HPGe and five LaBr3:Ce detectors
working in coincidence. Results on new and re-evaluated half-lives are
discussed within a systematic of transition rates. The states in
103,105,107Cd are interpreted as arising from a single-particle excitation. The
half-life analysis of the states in 103,105,107Cd shows no change in
the single-particle transition strength as a function of the neutron number
First g(2+) measurement on neutron-rich 72 Zn, and the high-velocity transient field technique for radioactive heavy-ion beams
The high-velocity transient-field (HVTF) technique was used to measure the g factor of the 2+ state of 72Zn produced as a radioactive beam. The transient-field strength was probed at high velocity in ferromagnetic iron and gadolinium hosts using 76Ge beams. The potential of the HVTF method is demonstrated and the difficulties that need to be overcome for a reliable use of the TF technique with high-Z, high-velocity radioactive beams are revealed. The polarization of K-shell vacancies at high velocity, which shows more than an order of magnitude difference between Z = 20 and Z = 30 is discussed. The g-factor measurement hints at the theoretically predicted transition in the structure of the Zn isotopes near N = 40
133In: A Rosetta Stone for decays of r-process nuclei
The decays from both the ground state and a long-lived isomer of
In were studied at the ISOLDE Decay Station (IDS). With a hybrid
detection system sensitive to , , and neutron spectroscopy, the
comparative partial half-lives (logft) have been measured for all their
dominant -decay channels for the first time, including a low-energy
Gamow-Teller transition and several First-Forbidden (FF) transitions. Uniquely
for such a heavy neutron-rich nucleus, their decays selectively
populate only a few isolated neutron unbound states in Sn. Precise
energy and branching-ratio measurements of those resonances allow us to
benchmark -decay theories at an unprecedented level in this region of
the nuclear chart. The results show good agreement with the newly developed
large-scale shell model (LSSM) calculations. The experimental findings
establish an archetype for the decay of neutron-rich nuclei southeast
of Sn and will serve as a guide for future theoretical development
aiming to describe accurately the key decays in the rapid-neutron
capture (r-) process
Beta-delayed neutron spectroscopy of In
The decay properties of In were studied in detail at the ISOLDE Decay
Station (IDS). The implementation of the Resonance Ionization Laser Ion Source
(RILIS) allowed separate measurements of its ground state (In)
and isomer (In). With the use of -delayed neutron and
spectroscopy, the decay strengths above the neutron separation energy
were quantified in this neutron-rich nucleus for the first time. The allowed
Gamow-Teller transition was located at 5.92 MeV in the
In decay with a logft = 4.7(1). In addition, several neutron-unbound
states were populated at lower excitation energies by the First-Forbidden
decays of In. We assigned spins and parities to those
neutron-unbound states based on the -decay selection rules, the logft
values, and systematics
Anomalies in the Charge Yields of Fission Fragments from the U(n,f)238 Reaction
Fast-neutron-induced fission of 238U at an energy just above the fission threshold is studied with a novel technique which involves the coupling of a high-efficiency Îł-ray spectrometer (MINIBALL) to an inverse-kinematics neutron source (LICORNE) to extract charge yields of fission fragments via ÎłâÎł coincidence spectroscopy. Experimental data and fission models are compared and found to be in reasonable agreement for many nuclei; however, significant discrepancies of up to 600% are observed, particularly for isotopes of Sn and Mo. This indicates that these models significantly overestimate the standard 1 fission mode and suggests that spherical shell effects in the nascent fission fragments are less important for low-energy fast-neutron-induced fission than for thermal neutron-induced fission. This has consequences for understanding and modeling the fission process, for experimental nuclear structure studies of the most neutron-rich nuclei, for future energy applications (e.g., Generation IV reactors which use fast-neutron spectra), and for the reactor antineutrino anomaly
Study of the onset of deformation and shape coexistence in Ar via the inverse kinematics () reaction
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