Tue·Mar 21, 2023Tuesday·March 21, 2023

1. 01*

   Cross Sections of the ${}^{83}$Rb(p,$\gamma {)}^{84}$Sr and ${}^{84}$Kr(p,$\gamma {)}^{85}$Rb Reactions at Energies Characteristic of the Astrophysical $\gamma$ Process

   M. Williams🇨🇦 · B. Davids🇨🇦 · G. Lotay🇬🇧 · N. Nishimura🇯🇵 · T. Rauscher🇨🇭 · S. A. Gillespie🇨🇦 · M. Alcorta🇨🇦 · A. M. Amthor🇺🇸 · G. C. Ball🇨🇦 · S. S. Bhattacharjee🇨🇦 · V. Bildstein🇨🇦 · W. N. Catford🇬🇧 and 13 other authors

   We have measured the cross section of the ${}^{83}$Rb(p,$\gamma {)}^{84}$Sr radiative capture reaction in inverse kinematics using a radioactive beam of ${}^{83}$Rb at incident energies of 2.4 and $2.7A$ MeV. Prior to the radioactive beam measurement, the ${}^{84}$Kr(p,$\gamma {)}^{85}$Rb radiative capture reaction was measured in inverse kinematics using a stable beam of ${}^{84}$Kr at an incident energy of $2.7A$ MeV. The effective relative kinetic energies of these measurements lie within the relevant energy window for the $\gamma$ process in supernovae. The central values of the measured partial cross sections of both reactions were found to be $0.17-0.42$ times the predictions of statistical model calculations. Assuming the predicted cross section at other energies is reduced by the same factor leads to a slightly higher calculated abundance of the $p$ nucleus ${}^{84}$Sr, caused by the reduced rate of the ${}^{84}$Sr($\gamma$,p)${}^{83}$Rb reaction derived from the present measurement.

   nucl-exastro-ph.SRPRC(2023)·8 citations
2. 02*

   Bayesian inference of in-medium baryon-baryon scattering cross sections from HADES proton flow data

   Bao-An Li🇺🇸 · Wen-Jie Xie🇨🇳

   Within a Bayesian statistical framework using a Gaussian Process emulator for an isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model simulator of heavy-ion reactions at intermediate energies, we infer from the HADES proton flow data the posterior probability distribution functions of in-medium baryon-baryon scattering cross section modification factor X with respect to free-space and the corresponding incompressibility K of nuclear matter as well as their correlation function. The mean value of X is found to be $X=1.32_{-0.40}^{+0.28}$ at 68\% confidence level assuming the nuclear incompressibility K will not exceed 400 MeV, providing circumstantial evidence for enhanced baryon-baryon scattering cross sections in hot and dense nuclear matter.

   ↳ nucl-thnucl-exNPA(2023)·15 citations
3. 03*

   Ultra-low radioactivity flexible printed cables

   Isaac J. Arnquist🇺🇸 · Maria Laura di Vacri🇺🇸 · Nicole Rocco🇺🇸 · Richard Saldanha🇺🇸 · Tyler Schlieder🇺🇸 · Raj Patel🇺🇸 · Jay Patil🇺🇸 · Mario Perez🇪🇸 · Harshad Uka🇺🇸

   Flexible printed cables and circuitry based on copper-polyimide materials are widely used in experiments looking for rare events due to their unique electrical and mechanical characteristics. However, past studies have found copper-polyimide flexible cables to contain 400-4700 pg ${}^{238}$U/g, 16-3700 pg ${}^{232}$Th/g, and 170-2100 ng ${}^{nat}$K/g, which can be a significant source of radioactive background for many current and next-generation ultralow background detectors. This study presents a comprehensive investigation into the fabrication process of copper-polyimide flexible cables and the development of custom low radioactivity cables for use in rare-event physics applications. A methodical step-by-step approach was developed and informed by ultrasensitive assay to determine the radiopurity in the starting materials and identify the contaminating production steps in the cable fabrication process. Radiopure material alternatives were identified, and cleaner production processes and treatments were developed to significantly reduce the imparted contamination. Through the newly developed radiopure fabrication process, fully-functioning cables were produced with radiocontaminant concentrations of 20-31 pg ${}^{238}$U/g, 12-13 pg ${}^{232}$Th/g, and 40-550 ng ${}^{nat}$K/g, which is significantly cleaner than cables from previous work and sufficiently radiopure for current and next-generation detectors. This approach, employing witness samples to investigate each step of the fabrication process, can hopefully serve as a template for investigating radiocontaminants in other material production processes.

   ↳ physics.ins-dethep-exnucl-exEPJ Tech.Instrum.(2023)·11 citations
4. 04*

   Prevailing Triaxial Shapes in Atomic Nuclei and a Quantum Theory of Rotation of Composite Objects

   T. Otsuka🇯🇵 · Y. Tsunoda🇯🇵 · N. Shimizu🇯🇵 · Y. Utsuno🇯🇵 · T. Abe🇯🇵 · H. Ueno

   In the traditional view, heavy deformed nuclei are like axially-symmetric prolate ellipsoids, rotating about one of the short axes. In the present picture, their shapes may be triaxial. The triaxial shape yields complex rotations, which actually well reproduce experimental data, as confirmed by state-of-the-art Configuration Interaction calculations. Two origins are suggested for the triaxiality: (i) binding-energy gain by the symmetry restoration for triaxial shapes, and (ii) another gain by specific components of the nuclear force, like tensor force and high-multipole (e.g. hexadecupole) central force. While the origin (i) produces basic smaller triaxiality for virtually all deformed nuclei, the origin (ii) produces medium triaxiality for a certain class of nuclei. An example of the former is 154Sm, a typical showcase of axial symmetry but is now suggested to depict a modest yet finite triaxiality. The latter, medium triaxiality, is discussed from various viewpoints for some exemplified nuclei including 166Er, and experimental findings. Many-body structures of the gamma band and the double-gamma band are clarified. Regarding the general features of rotational states of deformed many-body systems including triaxial ones, the well-known J(J+1) rule of rotational excitation energies is discussed, within the quantum mechanical many-body theory, without resorting to the quantization of a rotating classical rigid body. The picture of prevailing triaxial shapes thus emerges, where the empirically known rotational-band pattern appears with good K quantum number, but the internal structure is dfferent from conventional picture a la A. Bohr. The possible relations to Davydov's rigid-triaxial-rotor model are mentioned.

   ↳ nucl-thnucl-exEPJA(2025)·51 citations
5. 05*

   Report of the US ITER Research Program Research Needs Workshop

   Charles Greenfield · Cami Collins🇬🇧 · Workshop Participants

   The US ITER Research Program Basic Research Needs Workshop, held over the course of several months in 2022 with over 400 participants, sought to identify steps to be taken to both maximize the return of the US investment in ITER construction and operation and to ensure US research priorities on ITER strengthen the domestic program aimed at the development of a fusion pilot plant (FPP).

   ↳ physics.plasm-phnucl-ex0 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.