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The cross sections of 127I(n,γ)128I and 133Cs(n,γ)134Cs play a critical role in the s-process of nuclear astrophysics, the iodine–xenon chronometer on early meteorite evolution, and understanding the performance of CsI crystal detectors for Dark Matter Detection Experiment and Coherent Elastic Neutrino-Nucleus Scattering (CEνNS) experiments. The neutron capture cross sections of 127I and 133Cs were measured from 1 eV to 1 MeV using the time-of-flight method at China Spallation Neutron Source Back-n facility. The neutron capture yield was derived via the pulse-height weighting technique based on the total energy detection principle of C6D6 detectors. In the resolved resonance region (RRR), some new resonance peaks of 133Cs(n,γ) were observed for the first time. Resonance parameters for the neutron capture cross section were extracted using the SAMMY code from 1 eV to 4 keV, while averaged capture cross sections in the unresolved resonance region (URR) from 4 keV to 1 MeV were analyzed with TALYS. Results were compared with evaluated libraries and previous work in both RRR and URR. Astrophysical Maxwellian-averaged cross sections (MACS) were calculated for kT = 5–100 keV. At kT = 30 keV, the MACS of both 127I(n,γ)128I and 133Cs(n,γ)134Cs were slightly higher than those of the KADoNiS v0.3 recommended value. And the reaction rates were derived over the astrophysically relevant temperature range of s-process nucleosynthesis models. The uncertainties of present reaction rates are significantly reduced.

Observed abundances of Z ∼ 40 elements in metal-poor stars vary from star to star, indicating that the rapid and slow neutron capture processes may not contribute alone to the synthesis of elements beyond iron. The weak r-process was proposed to produce Z ∼ 40 elements in a subset of old stars. Thought to occur in the ν-driven ejecta of a core-collapse supernova, (α, xn) reactions would drive the nuclear flow toward heavier masses at T = 2−5 GK. However, current comparisons between modeled and observed yields do not bring satisfactory insights into the stellar environment, mainly due to the uncertainties of the nuclear physics inputs where the dispersion in a given reaction rate often exceeds 1 order of magnitude. Involved rates are calculated with the statistical model where the choice of an α-optical-model potential (αOMP) leads to such a poor precision. The first experiment on 87Rb(α, xn) reactions at weak r-process energies is reported here. Total inclusive cross sections were assessed at Ec.m. = 8.1−13 MeV (3.7−7.6 GK) with the active target MUlti-Sampling Ionization Chamber. With an N = 50 seed nucleus, the measured values agree with statistical model estimates using the αOMP Atomki-V2. A reevaluated reaction rate was incorporated into new nucleosynthesis calculations, focusing on ν-driven ejecta conditions known to be sensitive to this specific rate. These conditions were found to fail to reproduce the lighter heavy element abundances in metal-poor stars.

The secondary i- and s-processes that follow the r-process in collapsar outflows, characterized by low electron fraction Ye and decelerated expansion, can serve as a major source of rare earth element production. We systematically evaluated the contributions of the r-, i-, and s-processes to the production of rare earth elements in collapsar outflows. A sensitivity analysis of nucleosynthesis yields with respect to (n, γ) reaction rates involving unstable nuclei near the line of stability highlights dozens of key reactions critical for the synthesis of thulium (Z = 69) and lutetium (Z = 71). These specific (n, γ) reactions, however, have a negligible impact on the yields predicted in magnetohydrodynamically driven jets or binary neutron star mergers. Our nucleosynthesis models indicate that collapsars can produce elevated Tm/Eu and Lu/Eu abundance ratios, potentially serving as observational signatures distinguishing collapsar nucleosynthesis from others. The robustness of these predictions, however, is highly sensitive to uncertainties in the relevant nuclear reaction rates. We therefore emphasize the need for precise future experimental measurements of the (n, γ) cross sections for key unstable nuclei. Reducing these nuclear-physics uncertainties will allow collapsar models to predict Tm/Eu and Lu/Eu ratios with greater confidence, thereby improving our interpretation of observed abundances in r-process-enhanced metal-poor stars.

It is thought that photon vortices are predominantly produced in extremely strong magnetic fields in the Universe. Because the photon vortex may cause significant large angular momentum transfer in interactions with atomic nuclei, stellar nucleosynthesis in such astrophysical environments is affected. In the present study, we calculate the ratios of the photon absorption transition probabilities of photon vortices with Bessel wave to photons described by the plane wave. The result shows enhancement of excitation of states with large total angular momentum by optimization of the divergence angle of the incident photon vortex in momentum space. However, the average cross section for the photon vortex turns out to be identical with that for the plane wave. Therefore, even when Bessel photons are predominantly produced in astrophysical environments, the isotopic abundances of the synthesized elements are not changed.

The neutron-induced nuclear reaction data play an important role in the studies of the nuclear structure, the nuclear reaction mechanism and the nuclear energy applications. Particularly, the cross section data of the neutron-induced nuclear reactions are an indispensable component in the studies of the nuclear technology such as fusion devices, fission power plants, and accelerators. In the actual cross section measurements of the neutron-induced nuclear reactions with natural samples containing many stable isotopes, many nuclear reactions will take place at the same time and the mutual interference of various nuclear reactions is difficult to avoid. In this case, the standardization expressions of the neutron-induced nuclear reactions are particularly important. The expressions of the neutron-induced nuclear reactions in the relevant literatures are various and confusing, which is bad not only for the academic exchanges and the construction of nuclear reaction databases, but also for the basic research and the related application research of the nuclear physics. Some problems related to the expressions on the neutron-induced nuclear reactions were carefully combed and discussed, and the suggestions on the standardization expressions of the neutron-induced nuclear reactions (which were divided into the single nuclear reaction and the multiple nuclear reaction producing the same daughter nucleus. And the former was further divided into the daughter nucleus with metastable state and the daughter nucleus without metastable state, while the latter into the nuclear reaction that directly produces the same daughter nucleus and the nuclear reaction that directly and indirectly produces the same daughter nucleus) were given. The work is useful for the academic exchanges, the construction of the nuclear reaction databases, the basic researches and the related application researches of the nuclear physics.

Lutetium-177 (177Lu) radioisotope has been suggested for radioimmunotherapy application in nuclear medicine. Presently 177Lu has been mostly produced using neutron activation in nuclear reactors, whereas cyclotron-based production has not been well explored. In this paper, we theoretically propose cyclotron-based deuteron beams for 177Lu production. By Employing the TALYS 2017 codes, we calculated nuclear cross-sections and the End-of-Bombardment (EOB) yields of 176Yb(d,n) 177Lu reaction for direct production of 177Lu as well as 176Yb(d,p)177Yb→177Lu reaction for indirect production of 177Lu. The TALYS calculated cross-sections indicated that the threshold energy of both investigated nuclear reactions is 0 MeV; thus 177Lu could be produced at low deuteron energy bombardment, though significant amount of 177Lu radioactivity could only be generated for deuteron beams with energy greater than 6 MeV. The calculated EOB yields for 176Yb(d,n)177Lu reaction and 176Yb(d,p)177Yb reaction were 0.519 and 181.1 MBq/μAh respectively, which well agreed with previous experimental results published elsewhere. In conclusion, both nuclear reactions are possible for 177Lu production though the indirect method via 176Yb(d,p)177Yb→177Lu reaction would give much better EOB yield than that of direct method.

TALYS is a software package for the simulation of nuclear reactions below 200 MeV. It is used worldwide for the analysis and prediction of nuclear reactions and is based on state-of-art nuclear structure and nuclear reaction models. A general overview of the implemented physics and capabilities of TALYS is given. The general nuclear reaction mechanisms described are the optical model, direct reactions, compound nucleus model, pre-equilibrium reactions and fission. The most important nuclear structure models are those for masses, discrete levels, level densities, photon strength functions and fission barriers. A wide variety of nuclear reactions simulated with TALYS will be demonstrated, ranging from low-energy neutron cross sections, astrophysics, high-energy charged particle reactions and other reactions. TALYS is a nuclear reaction software which aims to give a complete description of nuclear reaction observables, and to be an important link between fundamental nuclear physics and applications.

. The article describes the main achievements of the NUMEN project together with an updated and detailed overview of the related R&D activities and theoretical developments. NUMEN proposes an innovative technique to access the nuclear matrix elements entering the expression of the lifetime of the double beta decay by cross section measurements of heavy-ion induced Double Charge Exchange (DCE) reactions. Despite the fact that the two processes, namely neutrinoless double beta decay and DCE reactions, are triggered by the weak and strong interaction respectively, important analogies are suggested. The basic point is the coincidence of the initial and final state many-body wave functions in the two types of processes and the formal similarity of the transition operators. First experimental results obtained at the INFN-LNS laboratory for the 40 Ca( 18 O, 18 Ne) 40 Ar reaction at 270MeV give an encouraging indication on the capability of the proposed technique to access relevant quantitative information. The main experimental tools for this project are the K800 Superconducting Cyclotron and MAGNEX spectrometer. The former is used for the acceleration of the required high resolution and low emittance heavy-ion beams and the latter is the large acceptance magnetic spectrometer for the detection of the ejectiles. The use of the high-order trajectory reconstruction technique, implemented in MAGNEX, allows to reach the experimental resolution and sensitivity required for the accurate measurement of the DCE cross sections at forward angles. However, the tiny values of such cross sections and the resolution requirements demand beam intensities much larger than those manageable with the present facility. The on-going upgrade of the INFN-LNS facilities in this perspective is part of the NUMEN project and will be discussed in the article.

The study of fusion reactions at extreme sub-barrier energies has seen an increased interest in recent years, although difficult to measure due to their very small cross sections. Such reactions are extremely important for our understanding of the production of heavy elements in various environments. In this article, the status of the field is reviewed covering the experimental techniques, the available data, and the theoretical approaches used to describe such reactions. The fusion hindrance effect, first discovered in medium-mass systems, has been found to be relevant also for lighter systems. In some light systems, resonance structures are found to be important, while for heavy systems, the fission process plays an important role. In the near barrier region, couplings to collective excitations in the fusion participants and transfer reactions have been found to give a good description of the measured fusion cross sections and it results in a distribution of fusion barrier heights. New physics ingredients, related to the overlap process of the two projectiles, have to be introduced to describe the hindrance behavior. In addition, it has recently been found that the fusion cross section in both near-barrier and sub-barrier regions can be described very well in many cases using simple, analytical forms of the barrier-height distributions or a modified version of the classic Wong formula.

The coherent elastic scattering of neutrinos off nuclei has eluded detection for four decades, even though its predicted cross section is by far the largest of all low-energy neutrino couplings. This mode of interaction offers new opportunities to study neutrino properties and leads to a miniaturization of detector size, with potential technological applications. We observed this process at a 6.7σ̃ confidence level, using a low-background, 14.6-kilogram CsI[Na] scintillator exposed to the neutrino emissions from the Spallation Neutron Source at Oak Ridge National Laboratory. Characteristic signatures in energy and time, predicted by the standard model for this process, were observed in high signal-to-background conditions. Improved constraints on nonstandard neutrino interactions with quarks are derived from this initial data set.