22 research outputs found
Emerging nuclear collectivity in Te
The emergence of nuclear collectivity near doubly-magic Sn was
explored along the stable, even-even Te isotopes. Preliminary
measurements of the transition strengths
are reported from Coulomb excitation experiments primarily aimed at measuring
the factors of the states. Isotopically enriched Te targets
were excited by 198-205 MeV Ni beams. A comparison of transition
strengths obtained is made to large-scale shell-model calculations with
successes and limitations discussed.Comment: 5 pages, 3 figures, Submitted to Proceedings HIAS 2019, EPJ Web of
Conference
Identification of significant strength in the transitions of Ni
The transition strength in the transitions of
Ni have been determined for the first time following a series of
measurements at the Australian National University (ANU) and the University of
Kentucky (UK). The CAESAR Compton-suppressed HPGe array and the Super-e
solenoid at ANU were used to measure the mixing ratio and
internal conversion coefficient of each transition following inelastic proton
scattering. Level half-lives, mixing ratios and -ray
branching ratios were measured at UK following inelastic neutron scattering.
The new spectroscopic information was used to determine the strengths.
These are the first transition strengths measured in
nuclei with spherical ground states and the component is found to be
unexpectedly large; in fact, these are amongst the largest transition
strengths in medium and heavy nuclei reported to date
Identification of Significant \u3cem\u3eE\u3c/em\u3e0 Strength in the 2\u3csub\u3e2\u3c/sub\u3e\u3csup\u3e+\u3c/sup\u3e → 2\u3csub\u3e1\u3c/sub\u3e\u3csup\u3e+\u3c/sup\u3e Transitions of \u3csup\u3e58,60,62\u3c/sup\u3eNi
The E0 transition strength in the 22+ → 21+ transitions of 58,60,62Ni have been determined for the first time following a series of measurements at the Australian National University (ANU) and the University of Kentucky (UK). The CAESAR Compton-suppressed HPGe array and the Super-e solenoid at ANU were used to measure the δ(E2/M1) mixing ratio and internal conversion coefficient of each transition following inelastic proton scattering. Level half-lives, δ(E2/M1) mixing ratios and γ-ray branching ratios were measured at UK following inelastic neutron scattering. The new spectroscopic information was used to determine the E0 strengths. These are the first 2+ → 2+ E0 transition strengths measured in nuclei with spherical ground states and the E0 component is found to be unexpectedly large; in fact, these are amongst the largest E0 transition strengths in medium and heavy nuclei reported to date
Shape polarization in the tin isotopes near from precision -factor measurements on short-lived isomers
The factors of isomers in semimagic Sn and Sn
(isomeric lifetimes ns and ns, respectively)
were measured by an extension of the Time Differential Perturbed Angular
Distribution technique, which uses \LaBr detectors and the hyperfine fields of
a gadolinium host to achieve precise measurements in a new regime of
short-lived isomers. The results,
and , are significantly lower in
magnitude than those of the isomers in the heavier isotopes and depart
from the value expected for a near pure neutron configuration.
Broken-symmetry density functional theory calculations applied to the sequence
of states reproduce the magnitude and location of this deviation. The
values are affected by shape core polarization; the odd
neutron couples to configurations in the
weakly-deformed effective core, causing a decrease in the -factor
magnitudes.Comment: 8 pages, 7 figures. Accepted in Physics Letters
Simulation and background characterisation of the SABRE South experiment
SABRE (Sodium iodide with Active Background REjection) is a direct detection
dark matter experiment based on arrays of radio-pure NaI(Tl) crystals. The
experiment aims at achieving an ultra-low background rate and its primary goal
is to confirm or refute the results from the DAMA/LIBRA experiment. The SABRE
Proof-of-Principle phase was carried out in 2020-2021 at the Gran Sasso
National Laboratory (LNGS), in Italy. The next phase consists of two full-scale
experiments: SABRE South at the Stawell Underground Physics Laboratory, in
Australia, and SABRE North at LNGS. This paper focuses on SABRE South and
presents a detailed simulation of the detector, which is used to characterise
the background for dark matter searches including DAMA/LIBRA-like modulation.
We estimate an overall background of 0.72 cpd/kg/keV in the energy range
16 keV primarily due to radioactive contamination in the crystals.
Given this level of background and considering that the SABRE South has a
target mass of 50 kg, we expect to exclude (confirm) DAMA/LIBRA modulation at
within 2.5 years of data taking
Simulation and background characterisation of the SABRE South experiment
Published online: 28 September 2023SABRE(Sodium iodide with Active Background REjection) is a direct detection darkmatter experiment based on arrays of radio-pureNaI(Tl) crystals.The experiment aims at achieving an ultra-low background rate and its primary goal is to confirm or refute the results from the DAMA/LIBRA experiment. The SABRE Proof-of-Principle phase was carried out in 2020–2021 at the Gran Sasso National Laboratory (LNGS), in Italy. The next phase consists of two full-scale experiments: SABRE South at the Stawell Underground Physics Laboratory, in Australia, and SABRE North at LNGS. This paper focuses on SABRE South and presents a detailed simulation of the detector, which is used to characterise the background for darkmatter searches includingDAMA/ LIBRA-like modulation. We estimate an overall background of 0.72 cpd/kg/keVee in the energy range 1–6 keVee primarily due to radioactive contamination in the crystals. Given this level of background and considering that the SABRE South has a target mass of 50 kg, we expect to exclude (confirm) DAMA/LIBRA modulation at 4 (5)σ within 2.5 years of data taking.E. Barberio ... I. Bolognino ... G. C. Hill ... K. T. Leaver ... P. McGee ... A. G. Williams ... et al. (SABRE South Collaboration
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
Decay spectroscopy with Solenogam at the ANU Heavy Ion Accelerator Facility
Solenogam is a recoil spectrometer designed and constructed for use at the Australian National University (ANU) Heavy-Ion Accelerator Facility (HIAF). The design enables the study of nuclear excitations populated by the decay of long-lived states such as isomers and radioactive ground states. Solenogam is comprised of high-sensitivity γ-ray and electron detector arrays coupled to a new 8-T solenoid. While the installation of the 8-T solenoid proceeds, off-line measurements have been made to characterise Solenogam’s performance. Gamma-electron coincidences in the electron capture decay of 182Re into 182W were used to investigate conversion coeffcients and γ-e– angular correlations. The measured conversion coeffcients show good agreement with theoretical calculations and have been used to extract E0/E2 mixing ratios for a number of J → J transitions. The angular correlations measured by the array are in qualitative agreement with theoretical calculations. However, the magnitudes of the correlations are attenuated by approximately 40% for reasons unknown at present. These results are the first full use of the Solenogam system for γ-e– coincidence measurements and have proven that the system is capable of highly-sensitive internal conversion analysis of complex decays
Hyperfine fields at Ga, Ge implanted into iron and gadolinium hosts at 6 K, and applications to g-factor measurements
Isomers in Ga, Ge, and Ge were recoil-implanted into
ferromagnetic hosts of iron and gadolinium at ~K, and the hyperfine
magnetic fields were determined by Time Differential Perturbed Angular
Distribution (TDPAD) measurements. The hyperfine field strengths at ~K are compared to the results of previous higher-temperature measurements
and the amplitudes of the functions are compared to empirical
expectations. The results show that gadolinium can be a suitable host for
high-precision in-beam -factor measurements. The results of new -factor
measurements for isomers in Ga and Ge are Ga, supporting a configuration
assignment, and Ge, derived from a new
measurement of the ratio .
These values are in agreement with previous results. The amplitudes
indicate that the nuclear alignment produced in the isomeric states was
significantly lower than the empirically expected .Comment: 10 pages, 10 figure