arXiv subjects

Andrew E. Stuchbery

Publications and source records attributed to Andrew E. Stuchbery.

9 recordsLinked to original sources

arXiv2026

Doppler-shift attenuation method (DSAM) lifetimes in $^{54}$Cr - a re-evaluation

Background: Contemporary stopping powers for fp-shell nuclei slowing in tantalum can differ by a factor of two from the 1963 Lindhard, Scharff and Schiøtt (LSS) theory [Mat. Fys. Medd. Dan. Vid. Selsk. 33 no. 14, (1963)] used in Doppler-shift attenuation method (DSAM) lifetime measurements dating back to the 1970s. In recent work [Phys. Rev. C 113, 044306 (2026)], it was found that anomalously high collectivity in the $4^+_1 \rightarrow 2^+_1$ transition of 58Fe given in the literature [Nucl. Data Sheets 111, 897 (2010)] could be traced back as due to the use of these historical stopping powers in the Doppler-shift lifetime measurements. Satisfactory agreement with shell-model calculations was obtained from a re-analysis of the measurement of Bolotin et al. [Nucl. Phys. A 311, 75 (1978)] once the stopping powers were replaced by up-to-date values. Purpose: The DSAM measurement on 54Cr by the same group [Nucl. Phys. A 337, 1 (1980)], which used the same experimental methods and procedures, is re-examined. Method: The computer code used in the original DSAM analysis has been rebuilt and upgraded with the capacity to use contemporary stopping powers. E2 transition strengths derived from the revised lifetimes are compared with shell-model calculations. Results: The lifetimes increase by 16% to 27%, with the larger increase generally corresponding to shorter lifetimes where electronic stopping dominates. Conclusions: Revised lifetimes, based on current stopping powers, imply E2 transition rates between states up to the 6$^+_1$ state in 54Cr that compare well with shell-model calculations. The lifetime data together with branching ratios and the shell-model calculations strongly suggest revision of the spins assigned to the levels at 3.786 (currently (4)$^+$) and 4.043 MeV (currently 5$^+$). These levels are suggested to be the 5$^+_1$ and 6$^+_2$ states, respectively.

nucl-ex↗

arXiv2026

Nuclear electromagnetic moments by spin-precession methods

Nuclear moment studies carried out with spin-precession methods at and after the turn of the millennium are critically assessed. A period of about 30 years is covered, during which much of} the focus of nuclear structure research shifted from high-spin physics to studies of neutron-rich exotic nuclei. The formalism for the extraction of nuclear moments is described. The $β$-nuclear magnetic resonance/nuclear quadrupole resonance ($β$-NMR/NQR), the time-dependent perturbed angular distribution (TDPAD), the transient field, the recoil-in-vacuum (RIV), and the tilted-foils methods for measurements of nuclear magnetic dipole and electric quadrupole moments are described in detail, as well as the requirements for their application in studies of exotic nuclei. The impact of nuclear-moment measurements on the understanding of key topics of nuclear structure research is discussed. {Key results on short-lived states, mainly from transient-field measurements, are reviewed. Included are comparisons with large-basis shell model calculations, discussions on the nature of weakly-collective nuclei, insights into emerging collectivity away from closed shells, and electromagnetic properties of odd-$A$ rotors.} In the field of high-spin physics, research related to high-spin yrast and $\mathrm{K}$ isomers, superdeformation, magnetic, anti-magnetic, and chiral rotation is covered. In neutron-rich exotic nuclei, studies related to the $\mathrm{N=20}$, $\mathrm{N=28}$ and $\mathrm{N=40}$ ``islands of inversion'', the structure of nuclei around $^{68-78}$Ni and $^{132}$Sn, and in the $A \sim 100$ mass region are discussed.

nucl-ex↗

arXiv2025

Detailed nuclear structure calculations for coherent elastic neutrino-nucleus scattering

Any discovery of `new physics' in the neutrino sector first requires a precise prediction of the expected Standard Model cross section. Currently, Coherent Elastic neutrino-Nucleus Scattering (CEvNS) experiments are statistics limited. However, as new and future experiments scale up, it will be necessary to improve the theoretical predictions. Here we review the calculation of the CEvNS cross section in a consistent theory of hadronic currents and compute the relevant nuclear form factors using the nuclear shell model. The uncertainty on the form factors is explored by repeating the calculation for various shell model interactions and with Skyme-Hartree-Fock evaluations of the Weak-charge radii. We then refine the Standard Model predictions for the recent experimental results of the COHERENT experiment. We find that our cross sections are in good agreement with previous predictions, but with significantly smaller uncertainties - by up to a factor of 10. Near-future CEvNS experiments will meaningfully benefit from improved predictions through an increased sensitivity to new-physics signals.

hep-ph↗

arXiv2023

Impact of shell model interactions on nuclear responses to WIMP elastic scattering

Background: Nuclear recoil from scattering with weakly interacting massive particles (WIMPs) is a signature searched for in direct detection of dark matter. The underlying WIMP-nucleon interactions could be spin and/or orbital angular momentum (in)dependent. Evaluation of nuclear recoil rates through these interactions requires accounting for nuclear structure, e.g., through shell model calculations. Purpose: To evaluate nuclear response functions induced by these interactions for $^{19}$F, $^{23}$Na, $^{28, 29, 30}$Si, $^{40}$Ar, $^{70,72,73,74,76}$Ge, $^{127}$I, and $^{128, 129, 130, 131, 132, 134, 136}$Xe nuclei that are relevant to current direct detection experiments, and to estimate their sensitivity to shell model interactions. Methods: Shell model calculations are performed with the NuShellX solver. Nuclear response functions from non-relativistic effective field theory (NREFT) are evaluated and integrated over transferred momentum for quantitative comparisons. Results: Although the standard spin independent response is barely sensitive to the structure of the nuclei, large variations with the shell model interaction are often observed for the other channels. Conclusions: Significant uncertainties may arise from the nuclear components of WIMP-nucleus scattering amplitudes due to nuclear structure theory and modelling. These uncertainties should be accounted for in analyses of direct detection experiments.

hep-ph↗

arXiv2022

Impact of nuclear structure from shell model calculations on nuclear responses to WIMP elastic scattering for $^{19}$F and $^{nat}$Xe targets

Non-relativistic effective field theory (NREFT) is one approach used for describing the interaction of WIMPs with ordinary matter. Among other factors, these interactions are expected to be affected by the structure of the atomic nuclei in the target. The sensitivity of the nuclear response components of the WIMP-nucleus scattering amplitude is investigated using shell model calculations for $^{19}$F and $^{nat}$Xe. Resulting integrated nuclear response values are shown to be sensitive to some specifics of the nuclear structure calculations.

hep-ph↗

arXiv2020

SABRE and the Stawell Underground Physics Laboratory: Dark Matter Research at the Australian National University

The direct detection of dark matter is a key problem in astroparticle physics that generally requires the use of deep-underground laboratories for a low-background environment where the rare signals from dark matter interactions can be observed. This work reports on the Stawell Underground Physics Laboratory - currently under construction and the first such laboratory in the Southern Hemisphere - and the associated research program. A particular focus will be given to ANU's contribution to SABRE, a NaI:Tl dark matter direct detection experiment that aims to confirm or refute the long-standing DAMA result. Preliminary measurements of the NaI:Tl quenching factor and characterisation of the SABRE liquid scintillator veto are reported.

physics.ins-det↗

arXiv2018

Pushing the limits of excited-state $g$-factor measurements

Current developments in excited-state $g$-factor measurements are discussed with an emphasis on cases where the experimental methodology is being extended into new regimes. The transient-field technique, the recoil in vacuum method, and moment measurements with LaBr$_3$ detectors are discussed.

nucl-ex↗

arXiv2006

Some notes on the program GKINT: Transient-field g-factor kinematics at intermediate energies

This report describes the computer program GKINT, which was developed to plan, analyze and interpret the first High Velocity Transient Field (HVTF) g-factor measurements on radioactive beams produced as fast fragments. The computer program and these notes were written in September 2004. Minor corrections and updates have been added to these notes since then. The experiment, NSCL experiment number 02020, 'Excited-state configurations in S-38 and S-40 through transient-field g-factor measurements on fast fragments', was performed in October 2004; results have been published in Physical Review Letters 96, 112503 (2006).

nucl-ex↗

arXiv1993

Critical test of multi-{\it j} supersymmetries from magnetic moment measurements

Magnetic moment measurements in odd nuclei directly probe the distribution of fermion states and hence provide one of the most critical tests for multi-$j$ supersymmetries in collective nuclei. Due to complexity of calculations and lack of data, such tests have not been performed in the past. Using the Mathematica software, we derive analytic expressions for magnetic moments in the $SO^{(BF)}(6) \times SU^{(F)}(2)$ limit of the $U(6/12)$ supersymmetry and compare the results with recent measurements in $^{195}$Pt.

nucl-th↗