Wed·Jun 15, 2022Wednesday·June 15, 2022

1. 01*

   Proton and neutron exchange as a prelude to fusion at near-barrier energies

   J.E. Johnstone🇺🇸 · Varinderjit Singh🇺🇸 · R. Giri🇺🇸 · S. Hudan🇺🇸 · J. Vadas🇺🇸 · R.T. deSouza🇺🇸 · D. Ackermann🇫🇷 · A. Chbihi🇫🇷 · Q. Hourdille🇫🇷 · A. Abbott🇺🇸 · C. Balhoff🇺🇸 · A. Hannaman🇺🇸 and 11 other authors

   Systematic examination of fusion for ${}^{39,41,45,47}$K + ${}^{28}$Si and ${}^{36,44}$Ar + ${}^{28}$Si provides insight into the impact of neutron and proton exchange on fusion for nuclei at and near the N=20 and N=28 shells. Comparison of the reduced excitation functions reveals a marked difference between the behavior of open-shell and closed-shell systems. While coupled channels calculations provide a good description for the closed-shell nuclei they significantly under-predict the fusion cross-section for open-shell nuclei. The observed trends are examined in the context of a potential energy surface, including shell effects, and multi-nucleon exchange with consideration of Pauli-blocking.

   nucl-exnucl-thPRC(2022)·4 citations
2. 02*

   Determining $g_A/g_V$ with High Resolution Spectral Measurements Using an LiInSe${}_2$ Bolometer

   A.F. Leder🇺🇸 · D. Mayer🇺🇸 · J.L. Ouellet🇺🇸 · F.A. Danevich🇺🇦 · L. Dumoulin🇫🇷 · A. Giuliani🇫🇷 · J. Kostensalo🇫🇮 · J. Kotila🇫🇮 · P. de Marcillac🇫🇷 · C. Nones🇫🇷 · V. Novati🇫🇷 · E. Olivieri🇫🇷 and 5 other authors

   Neutrinoless Double-Beta decay (0$\nu \beta \beta$) processes sample a wide range of intermediate forbidden nuclear transitions, which may be impacted by quenching of the axial vector coupling constant ($g_A/g_V$), the uncertainty of which plays a pivotal role in determining the sensitivity reach of 0$\nu \beta \beta$ experiments. In this Letter, we present measurements performed on a high-resolution LiInSe${}_2$~ bolometer in a ''source=detector'' configuration to measure the spectral shape of the 4-fold forbidden $\beta$-decay of ${}^{115}$In. The value of $g_A/g_V$ is determined by comparing the spectral shape of theoretical predictions to the experimental $\beta$ spectrum taking into account various simulated background components as well as a variety of detector effects. We find evidence of quenching of $g_A/g_V$ at $>5\sigma$ with a model-dependent quenching factor of $0.655\pm 0.002$ as compared to the free-nucleon value for the Interacting Shell Model. We also measured the ${}^{115}$In half-life to be [$5.18\pm 0.06(\text{stat.}{)}_{-0.015}^{+0.005}(\text{sys.})]\times {10}^{14}$ yr within the Interacting Shell Model framework. This work demonstrates the power of the bolometeric technique to perform precision nuclear physics single-$\beta$ decay measurements, which can help reduce the uncertainties in the calculation of $0\nu \beta \beta$ nuclear matrix elements.

   nucl-exhep-exphysics.ins-detPRL(2022)·26 citations
3. 03*

   Exploration of Methods to Remove Implanted ${}^{210}$Pb and ${}^{210}$Po Contamination from Silicon Surfaces

   Isaac J. Arnquist🇺🇸 · Raymond Bunker🇺🇸 · Zdenek Dohnalek🇺🇸 · Runze Ma🇺🇸 · Nicolas Uhnak🇺🇸

   Radioactive contaminants on the surfaces of detector components can be a problematic source of background events for physics experiments searching for rare processes. Exposure to radon is a specific concern because it can result in the relatively long-lived ${}^{210}$Pb (and progeny) being implanted to significant subsurface depths such that removal is challenging. In this article we present results from a broad exploration of cleaning treatments to remove implanted ${}^{210}$Pb and ${}^{210}$Po contamination from silicon, which is an important material used in several rare-event searches. We demonstrate for the first time that heat treatments ("baking") can effectively mitigate such surface contamination, with the results of a 1200 ${}^{\circ }$C bake consistent with perfect removal. We also report results using wet-chemistry and plasma-based methods, which show that etching can be highly effective provided the etch depth is sufficiently aggressive. Our survey of cleaning methods suggests consideration of multiple approaches during the different phases of detector construction to enable greater flexibility for efficient removal of ${}^{210}$Pb and ${}^{210}$Po surface contamination

   ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2023)·0 citations
4. 04*

   Supernova Dust Evolution Probed by Deep-sea 60Fe Time History

   Adrienne F. Ertel🇺🇸 · Brian J. Fry🇺🇸 · Brian D. Fields🇺🇸 · John Ellis🇬🇧

   There is a wealth of data on live, undecayed 60Fe ($t_{1/2}=2.6\mathrm{Myr}$) in deep-sea deposits, the lunar regolith, cosmic rays, and Antarctic snow, which is interpreted as originating from the recent explosions of at least two near-Earth supernovae. We use the 60Fe profiles in deep-sea sediments to estimate the timescale of supernova debris deposition beginning $\sim 3$ Myr ago. The available data admits a variety of different profile functions, but in all cases the best-fit 60Fe pulse durations are $>1.6$ Myr when all the data is combined. This timescale far exceeds the $\lesssim 0.1$ Myr pulse that would be expected if 60Fe was entrained in the supernova blast wave plasma. We interpret the long signal duration as evidence that 60Fe arrives in the form of supernova dust, whose dynamics are separate from but coupled to the evolution of the blast plasma. In this framework, the $>1.6$ Myr is that for dust stopping due to drag forces. This scenario is consistent with the simulations in Fry et. al (2020), where the dust is magnetically trapped in supernova remnants and thereby confined around regions of the remnant dominated by supernova ejects, where magnetic fields are low. This picture fits naturally with models of cosmic-ray injection of refractory elements as sputtered supernova dust grains and implies that the recent 60Fe detections in cosmic rays complement the fragments of grains that survived to arrive on the Earth and Moon. Finally, we present possible tests for this scenario.

   ↳ astro-ph.HEastro-ph.SRnucl-exphysics.geo-phApJ(2023)·16 citations
5. 05*

   Implications of parity-violating electron scattering experiments on ${}^{48}$Ca (CREX) and ${}^{208}$Pb (PREX-II) for nuclear energy density functionals

   Esra Yüksel🇹🇷 · Nils Paar🇭🇷

   Recent precise parity-violating electron scattering experiments on ${}^{48}$Ca (CREX) and ${}^{208}$Pb (PREX-II) provide a new insight on the formation of neutron skin in nuclei. Within the energy density functional (EDF) framework, we investigate the implications of CREX and PREX-II data on nuclear matter symmetry energy and isovector properties of finite nuclei: neutron skin thickness and dipole polarizability. The weak-charge form factors from the CREX and PREX-II experiments are employed directly in constraining the relativistic density-dependent point coupling EDFs. The EDF established with the CREX data acquires considerably smaller values of the symmetry energy parameters, neutron skin thickness and dipole polarizability both for ${}^{48}$Ca and ${}^{208}$Pb, in comparison to the EDF obtained using the PREX-II data, and previously established EDFs. Presented analysis shows that CREX and PREX-II experiments could not provide consistent constraints for the isovector sector of the EDFs, and further theoretical and experimental studies are required.

   ↳ nucl-thnucl-exPLB(2023)·56 citations
6. 06*

   Impact of fragment formation on shear viscosity in the nuclear liquid-gas phase transition region

   X. G. Den · P. Danielewicz🇺🇸 · Y. G. Ma🇨🇳 · H. Lin🇺🇸 · Y. X. Zhang🇨🇳

   Within the improved quantum molecular dynamic (ImQMD) model we follow the evolution of nuclear matter for planar Couette flow in a periodic box. We focus on the region of liquid-gas phase transition and extract the shear viscosity coefficient from the local stress tensor, directly following viscosity definition. By switching on and off the mean field and thus inducing the phase transition, we are able to observe the impact of clumping in the phase-transition region onto the viscosity.

   ↳ nucl-thnucl-exPRC(2022)·19 citations
7. 07*

   Semi-local nuclear forces from chiral EFT: State-of-the-art & challenges

   E. Epelbaum🇩🇪 · H. Krebs🇩🇪 · P. Reinert🇩🇪

   Recently, a new generation of nuclear forces has been developed in the framework of chiral EFT. An important feature of these potentials is a novel semi-local regularization approach that combines the advantages of a local regulator for long-range interactions with the convenience of an angle-independent nonlocal regulator for contact interactions. The authors discuss the key features of the semi-local two-nucleon potentials and demonstrate their outstanding performance in the two-nucleon sector by showing selected results up to fifth order in the EFT expansion. Also reviewed are applications to heavier systems, which are currently limited to third chiral order. This limitation reflects the conceptual difficulty in constructing a consistently regularized many-body forces and current operators and affects all currently available interactions. The authors outline possible ways to tackle this problem and discuss future directions in the field.

   ↳ nucl-thnucl-ex18 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.