arXiv subjects

A. G. Smith

Publications and source records attributed to A. G. Smith.

3 recordsLinked to original sources

arXiv2026

Emerging collectivity and phase transition in mass A$\approx$150 region. New information for Nd isotopes

Low and medium spin excitations in $^{146,148,150,152}$Nd isotopes, populated in $β^-$ decay of corresponding Pr isotopes or in prompt-$γ$ fission of $^{252}$Cf have been studied using Gammasphere array of Ge spectrometers. 159 new levels, including two new isomers, 305 new $γ$ transitions and 83 new spin-parity assignments were added in the four studied nuclei. The structure of excited levels in the studied Nd isotopes is discussed using phenomenological classifications and systematics and compared to calculations reported in other works. Particular attention is paid to $0^+$ and $2^+$ excitations related to the emerging quadrupole collectivity and to the role of the 11/2$^-$[505] neutron extruder in the process.

nucl-ex↗

arXiv2023

Direct Determination of Fission-Barrier Heights Using Light-Ion Transfer in Inverse Kinematics

We demonstrate a new technique for obtaining fission data for nuclei away from $β$-stability. These types of data are pertinent to the astrophysical \textit{r-}process, crucial to a complete understanding of the origin of the heavy elements, and for developing a predictive model of fission. These data are also important considerations for terrestrial applications related to power generation and safeguarding. Experimentally, such data are scarce due to the difficulties in producing the actinide targets of interest. The solenoidal-spectrometer technique, commonly used to study nucleon-transfer reactions in inverse kinematics, has been applied to the case of transfer-induced fission as a means to deduce the fission-barrier height, among other variables. The fission-barrier height of $^{239}$U has been determined via the $^{238}$U($d$,$pf$) reaction in inverse kinematics, the results of which are consistent with existing neutron-induced fission data indicating the validity of the technique.

nucl-ex↗

arXiv2022

Thermal Testing for Cryogenic CMB Instrument Optical Design

Observations of the Cosmic Microwave Background rely on cryogenic instrumentation with cold detectors, readout, and optics providing the low noise performance and instrumental stability required to make more sensitive measurements. It is therefore critical to optimize all aspects of the cryogenic design to achieve the necessary performance, with low temperature components and acceptable system cooling requirements. In particular, we will focus on our use of thermal filters and cold optics, which reduce the thermal load passed along to the cryogenic stages. To test their performance, we have made a series of in situ measurements while integrating the third receiver for the BICEP Array telescope. In addition to characterizing the behavior of this receiver, these measurements continue to refine the models that are being used to inform design choices being made for future instruments.

astro-ph.IM↗