Nuclear Experiment·nucl-ex
6 papers—1 primary·5 cross-listed·reconstructed*
The 2023 update of the discovery of nuclide project is presented when thirteen nuclides were observed for the first time. In addition, a major update and revision of the isotope discovery project is described.
Caroline E. P. Robin🇩🇪 · Gabriel Martínez-Pinedo🇩🇪
We compute -decay half-lives of isotonic nuclear chains located at neutron shell closures , , and , which are of particular importance for the -process nucleosynthesis, and study the role of first-forbidden transitions in a framework that includes complex nucleonic correlations beyond the quasiparticle random phase approximation. Such correlations are accounted for by coupling single nucleons to collective degrees of freedom (nuclear vibrations), and are found essential to reproduce available experimental -decay rates and more precise many-body methods. We find that the nucleon-vibration correlations tend to decrease the probability of decay via first-forbidden transition near stability, as they enhance Gamow-Teller transitions at low energy. While in the lighter systems allowed transitions dominate, the decay of and nuclei is found to occur to a large extent via first-forbidden transitions, and in particular those induced by and operators. Overall the many-body method based on nucleon-vibration coupling provides an ideal framework for future large-scale calculations. Upcoming experimental measurements of -decay rates in the region by radioactive-beam facilities will be crucial in order to validate the approach.
V. Guzey (Jyvaskyla U. and Helsinki Inst. of Phys.)🇫🇮
In this contribution, we summarize NLO pQCD predictions for inclusive and diffractive dijet photoproduction in Pb-Pb UPCs at the LHC. We demonstrate that the theory describes well the preliminary ATLAS data on the inclusive cross section, which probes nuclear parton distributions (PDFs) down to and which can reduce current uncertainties of the small- nuclear gluon distribution by approximately a factor of 2. Employing predictions of the leading twist approach to nuclear shadowing for nuclear diffractive PDFs, we calculate the cross section of diffractive dijet photoproduction and show that its dependence is sensitive to the effect of nuclear shadowing and the mechanism of QCD factorization breaking in hard diffraction. We also find that due to large leading twist nuclear shadowing and restricted kinematics, the diffractive contribution to the inclusive cross section of dijet photoproduction does not exceed %, which helps with an ambiguous interpretation of the ATLAS data.
Jordan McGinn🇬🇧 · Arunava Mukherjee🇮🇳 · Jessica Irwin🇬🇧 · Christopher Messenger · Michael J. Williams · Ik Siong Heng🇬🇧
The first direct detection of gravitational waves from binary neutron stars on the 17th of August, 2017, (GW170817) heralded the arrival of a new messenger for probing neutron star astrophysics and provided the first constraints on neutron star equation of state from gravitational wave observations. Significant computational effort was expended to obtain these first results and therefore, as observations of binary neutron star coalescence become more routine in the coming observing runs, there is a need to improve the analysis speed and flexibility. Here, we present a rapid approach for inferring the neutron star equation of state based on Normalising Flows. As a demonstration, using the same input data, our approach, ASTREOS, produces results consistent with those presented by the LIGO-Virgo collaboration but requires < 1 sec to generate neutron star equation of state confidence intervals. Furthermore, ASTREOS allows for non-parametric equation of state inference. This rapid analysis will not only facilitate neutron star equation of state studies but can potentially enhance future alerts for electromagnetic follow-up observations of binary neutron star mergers.
C. R. Ding🇨🇳 · Gang Li🇨🇳 · J. M. Yao🇨🇳
Nuclear matrix elements (NMEs) for neutrinoless double-beta () decay in candidate nuclei play a crucial role in interpreting results from current experiments and in designing future ones. Accurate NME values serve as important nuclear inputs for constraining parameters in new physics, such as neutrino mass and the Wilson coefficients of lepton-number-violating (LNV) operators. In this study, we present a comprehensive calculation of NMEs for decay in Ge, Se, Mo, Te, and Xe, using nuclear wave functions obtained from multi-reference covariant density functional theory (MR-CDFT). We employ three types of transition potentials at the leading order in chiral effective field theory. Our results, along with recent data, are utilized to constrain the coefficients of LNV operators. The results demonstrate that the combined NMEs based on the Feynman diagrams at the hadronic scale for the nonstandard mechanisms lead to uncertainty by different nuclear models comparable to that for the standard mechanism. The use of NMEs from various nuclear models does not dramatically change the parameter space intervals for the coefficients, although MR-CDFT yields the most stringent constraint. Furthermore, our NMEs can also be used to perform a more comprehensive analysis with multiple isotopes.
In line with the tradition of employing nuclear reactors for neutrino physics research, we present potential experiments that could be undertaken using the new Brazilian neutron source, the Brazilian Multipurpose Reactor (RMB). This upcoming facility has clearly defined objectives, including the production of radioisotopes for the healthcare system, material irradiation testing, and research using neutron beams to investigate the micro and mesostructures of various materials. However, we anticipate that the RMB will generate up to antineutrinos daily, potentially expanding the facility's scope to include neutrino physics experiments involving beta and inverse beta reactions. The modern operational conditions of the RMB and its location in the Iperó-Brazil region may also enable neutrino oscillation experiments and the determination of the parameter, as well as support safeguards activities by the International Atomic Energy Agency (IAEA), allowing for the monitoring of nuclear fuel burning cycles and isotope fractions. We discuss the potential utilization of the RMB as an antineutrino source, proposing experiments and addressing associated technical limitations.
* 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.