In the interest of exploring resonant contributions to the radiative capture reaction ^45 V(p, γ ) ^46 Cr, which is identified to impact the ^44 Ti nucleosynthesis in Core Collapse Supernovae at astrophysical energies, we performed a spectroscopic study of ^46 Cr through the β -decay of the progenitor ^46 Mn. We present new results on the decay scheme of the proton-rich exotic nucleus ^46 Mn based on a new approach at the level of the experimental data analysis. ^46 Mn was produced among other nuclei at the LISE3 fragment separator operated in GANIL using the fragmentation technique. The novel approach is compared with a traditional data analysis, and validated using the known decay scheme of ^45 Cr. The observed level scheme of the nucleus ^46 Cr is compared with previous works. This work confirms former experimental results, while presenting better statistics and revealing new transitions in the decay scheme.
This letter reports on the identification of a new isomeric state of ^164 Tb ( Z=65 , N=99 ), which was measured with the DESPEC setup at the GSI Helmholtzzentrum für Schwerionenforschung GmbH following the first relativistic fragmentation of an ^170 Er primary beam. From the time distribution and coincidences of the emitted γ rays, the isomer is tentatively assigned to a state with spin-parity (7^-) at an excitation energy of 283.3(2) keV with a half-life of 159(11) ns . The isomer is interpreted as the π 7/2^-[523]⊗ν 7/2^+[633] configuration from the Nilsson orbital systematics. These results represent the first report of γ -ray spectroscopy of ^164 Tb, providing insight into the ground-state and low-lying level structure.
The response of the ^3 He neutron long counter TETRA was investigated through detailed Monte Carlo simulations. Two analysis methods, based on the positive correlation between neutron-energy and penetration depth in the moderator, were developed to extract coarse spectral information from ^3 He long counters, although such detectors are not designed for neutron spectroscopy. The methods were first benchmarked offline using a ^252 Cf spontaneous-fission source, and then applied to online data collected at the ALTO facility. For the beta-delayed neutron precursor ^82 Ga, TETRA-based analyses result in a mean neutron-energy in the range 0.43–0.49 MeV and indicate that a significant fraction of the strength lies below a few hundred keV. In a second ALTO experiment, the time-of-flight spectrometer MONSTER was used to perform β -delayed neutron spectroscopy of ^82 Ga for the first time, providing an independent experimental reference above its detection threshold. The overall consistency between the TETRA-based results and the ToF measurement supports the use of these methods as a practical complementary tool for β -delayed neutron spectroscopy, in particular in the low-energy region where ToF techniques are intrinsically limited by thresholds and geometrical efficiency.
The SPES facility at the Legnaro National Laboratories is one of the most promising ISOL facilities currently under construction in Europe. Dedicated to basic nuclear science and nuclear-physics-based applications, it will deliver high-intensity, high-quality beams of unstable, mainly neutron-rich, isotopes at energies around the Coulomb barrier, enabling a wide range of projectile–target combinations. The technical solutions developed for SPES define it as an intermediate step towards a potential future European ISOL facility (EURISOL). SPES is based on a high-intensity production cyclotron, BEST-70p, which serves as the primary accelerator. The high-intensity proton beam is used to induce fission in a uranium carbide (UCx) direct target capable of sustaining a maximum power of 8 kW. The project aims to achieve a fission rate in the target of the order of 10 ^13 fissions per second. Exotic nuclei, after thermal extraction from the target, ionization, and isotopic separation, are re-accelerated by the ALPI superconducting linear accelerator. Secondary beams with energies of about 10 MeV/A, for mass numbers up to A=200, will be provided, with expected intensities of the order of 10 ^7 –10 ^9 particles per second for the most prolific species. This article presents a brief outline of the facility, describing the technical solutions adopted, followed by a concise description of the superconducting linac and an overview of the foreseen scientific program. In November 2024, the first SPES secondary beam of ^28 Al was successfully extracted from the ISOL source. The radioactive ions were laser-ionized, selected, and their decay characterized by β -decay.
We employ the QCD sum rule method to study the semileptonic weak decay of the single bottom baryon Ω _b^* with spin 3/2 into the single charmed baryon Ω _c^* with spin 3/2 , corresponding to a 3/2→3/2 weak transition. A three-point correlation function is calculated in both the physical and theoretical sides to derive the sum rules for the form factors of the transition. The analysis incorporates both the perturbative and non-perturbative contributions up to mass dimension six. After determining the working regions of the auxiliary parameters and performing numerical calculations of the sum rules of the form factors, we extract the q^2 -dependent fit functions for the form factors. The obtained fit functions are then applied to compute the decay widths of the Ω _b^*→Ω _c^*ℓν̅_ℓ transition in all lepton channels. Our results may serve as useful theoretical benchmarks for future experimental investigations of the semileptonic Ω _b^*→Ω _c^*ℓν̅_ℓ weak decays and the weak dynamics of excited heavy baryons.
Elastic scattering of fast neutrons at an incident energy of 30.8 MeV on a natural cerium target was measured during an experiment conducted at the Neutrons For Science facility at GANIL-SPIRAL2. This is the first measurement on cerium using incident neutron energy above 20 MeV. The differential cross-section up to 40 ^∘ in the centre-of-mass frame was extracted using the MONSTER liquid scintillator array for the scattered neutron detection. The experimental results are compared to global optical-model calculations, providing an overall very good agreement and a useful benchmark at intermediate energy.
Abstract Elastic scattering of fast neutrons at an incident energy of 30.8 MeV on a natural cerium target was measured during an experiment conducted at the Neutrons For Science facility at GANIL-SPIRAL2. This is the first measurement on cerium using incident neutron energy above 20 MeV. The differential cross-section up to 40 $$^\circ $$ ∘ in the centre-of-mass frame was extracted using the MONSTER liquid scintillator array for the scattered neutron detection. The experimental results are compared to global optical-model calculations, providing an overall very good agreement and a useful benchmark at intermediate energy.
We present the design, developments, and test results of the new scintillating fiber based tracking detectors which are part of the R ^3 B experimental setup at GSI and FAIR, Darmstadt, Germany. Those tracking detectors are capable to track heavy ions of all charges at relativistic energies. Together with an elaborate particle-tracking system, the full identification of relativistic ions from hydrogen up to uranium in mass and nuclear charge is possible.
We present a systematic study of forward-rapidity D^0 – D̅^0 azimuthal angular correlations in pp collisions at √(s) = 8.8 TeV and p–Pb collisions at √(s__NN) = 8.8 TeV using PYTHIA8. The analysis explores the interplay between parton distribution functions, color-reconnection models, and beam-remnant dynamics within a differential framework in trigger and associated p_T . In pp collisions, the correlation structure is found to be sensitive to both PDF choice and hadronization modelling. The use of modern PDFs (NNPDF4.0) leads to a reduction of near- and away-side per-trigger yields compared to the default set (NNPDF2.3), accompanied by a modification of the relative contributions of pair-creation, gluon-splitting, and flavor-excitation like topologies. These effects are consistent with a shift in the sampled (x, Q^2) phase space and an increased kinematic separation of charm pairs within the experimental acceptance. Differences between MonashF (NNPDF4.0) and QCDCRF (NNPDF4.0) tunes are primarily driven by CR dynamics, with the QCD-inspired reconnection scheme enhancing near-side correlations at low p_T and reducing away-side yields at higher p_T . The impact of forward-tuned configurations is found to be strongly PDF-dependent, indicating a non-trivial interplay between beam-remnant modelling and the low-scale partonic structure. In p–Pb collisions, the nuclear modification factor I_pPb is observed to show p_T dependence for PYTHIA’s default tune. It also shows strong p_T dependence, largely governed by the pp baseline, after using nuclear PDFs. These results demonstrate that forward heavy-flavor correlations provide a sensitive probe of small-x gluon dynamics and nonperturbative color treatment, and establish a baseline for future measurements in forward rapidity.
Comprehensive descriptions of multichannel hadronic dynamics within coupled-channel frameworks often involve substantial computational cost and parameter degeneracies. In this work, we present a computationally efficient framework for π N partial-wave fitting that combines relativistic Breit–Wigner resonance amplitudes, a Chebyshev-polynomial background parametrization, and Trust-Region Reflective optimization. The framework is applied to twelve π N partial-wave solutions from the SAID WI08 database for center-of-mass energies up to W ≈ 2 GeV . The fitted channels are examined across three phenomenological regimes: resonance-dominated, threshold-sensitive, and background-dominated behaviors. In resonance-dominated cases, the obtained effective masses and widths exhibit qualitative consistency with the characteristic scales reported by the Particle Data Group. In more complex regimes, the framework qualitatively reproduces threshold effects and the global phase motion of the amplitudes despite strong inelastic contributions. Because the present approach employs simplified resonance and background parametrizations without coupled-channel dynamics or unitarity constraints, the resulting parameters should be interpreted as effective phenomenological quantities rather than precision determinations of physical pole properties. Owing to its computational efficiency and conceptual simplicity, the framework may serve as a practical complementary tool for rapid exploratory studies, initialization of more sophisticated fitting procedures, systematic sensitivity investigations, and educational applications in π N partial-wave phenomenology.
Interactions of tetraneutrons, which are assumed to be produced in the nuclear fission process, with nuclei are studied in the framework of optical and Hauser–Feshbach statistical models. It predicts a large probability of ^89 Sr production for the tetraneutron-induced reaction on ^88 Sr compared to other isotopes. The same technique is applied to the tetraneutron-induced reaction on ^27 Al and the hexaneutron-induced reaction on natural zinc to revisit two historical multi-neutron experiments performed in the past.
Reactor decay heat is due to the decay of both fission products and neutron activated fuel and reactor materials. At relatively short cooling times it is dominated by the beta decay of fission products. The calculation of the decay heat contribution of a particular fission product depends on the proper assignment of the probability of population of each excited state in the daughter nucleus following beta decay. These decay probabilities and the energy distribution of the continuous beta spectra determine both the unrecoverable energy taken away by the neutrinos and the distribution of decay heat between gamma rays and beta particles. The latter is important for further radiation transport modeling, for instance to determine the volume over which the heat is deposited. This paper describes recent advances in measurement and modeling of selected fission products and the impact for JEFF evaluations.
We develop several equations of state (EOSs) for β -stable dense hadronic matter at both zero and finite temperatures, considering the potential occurrence of a quark–hadron crossover transition. These scenarios can actually occur in various astrophysical contexts, such as in the postmerger compact object formed during binary neutron star (BNS) mergers, in core-collapse supernovae (CCSNe), or in the early stages of a newly formed neutron star (protoneutron star, PNS). In order to describe the hadronic phase we use the DDME2 model which is based on a relativistic-mean-field (RMF) theory, while for the quark phase we employ a popular version of the three-flavors Nambu–Jona–Lasinio (NJL) model. In the hadronic phase, in addition to nucleons and leptons, we examine the effects and implications of potential hyperon formation. The crossover transition is modeled on existing data from low density lattice Quantum Chromodynamics (QCD) calculations. For each model we study thermal and neutrino trapping effects on the matter composition and consequently on the EOS. We ultimately determine the PNS static structure integrating the Tolman–Oppenheimer–Volkoff (TOV) equations. Our findings indicate that the presence of hyperons significantly hinders the development of quark matter during a crossover transition. In fact, with hyperonic matter, it becomes quite challenging to differentiate between EOSs with and without a crossover. Conversely, if only nucleons are present in the hadronic phase, the EOS with a crossover transition is notably softer compared to the pure nucleonic one, making it theoretically possible to distinguish between the two EOSs. Additionally, we observe that in the presence of a crossover transition, neutrino trapping results in a stiffer EOS. This outcome is independent of the particle composition of the hadronic phase, whether hyperons are included or not.
The internal composition of neutron stars remains one of the most significant uncertainties in nuclear astrophysics, specifically regarding the possible existence of deconfined quark matter at extremely high nuclear densities. We aim to identify robust multi-messenger signatures of a hadron-quark phase transition by analyzing the relationship between static stellar properties, tidal deformability, and post-merger gravitational-wave dynamics. Utilization of a suite of hybrid Equations of State (EoS), including the JJ(VQCD) and OOS(DD2_FRG) models, and comparing them against purely nucleonic baselines. Using a Python-based pipeline, we model the mass–radius relationship as well as calculate dimensionless tidal deformability (Λ ) . Further employment of universal relations to predict the peak post-merger frequency (f_2) and dynamical ejecta properties for a GW170817-like event. Hybrid models naturally reconcile the high-mass constraint of M ≥ 2.01 M_⊙ with the “soft” tidal response (Λ̃≈ 300) observed in GW170817. A significant finding is a characteristic shift in the post-merger regime: hybrid remnants exhibit f_2 frequencies 300–500 Hz lower than hadronic models. This spectral softening is accompanied by an increase in dynamical ejecta mass, resulting in a kilonova transient up to 0.5 magnitudes brighter than those predicted by standard hadronic EoS. The strong correlation (r ≈ -0.99) between inspiral tidal parameters and post-merger frequency provides a “smoking gun” for identifying quark matter. These signatures offer a definitive diagnostic for detectors which are third generation like the Einstein Telescope to probe the QCD phase diagram.
Statistical code (PACE) calculations were used to obtain the fission time scales using the experimental M ^pre values for ^16,18 O+ ^194,198 Pt reactions (experiment was performed at the 15 UD Pelletron accelerator facility of the Inter University Accelerator Centre (IUAC), New Delhi) [1]. PACE provides baseline statistical (non-dissipative) prediction and the excess neutrons relative to PACE are interpreted as due to dynamical/transient effects. The extracted results are also combined with the results obtained from nearby systems available in the literature. Combining all these results systematics of fission time scales is presented here and an enhanced delay was observed for the shell-closed compound nucleus ^212 Rn (N = 126) in the present data. The extracted effective fission delay times are further discussed in connection with previously measured evaporation residue and fission observables for the same reaction systems. The combined analysis provides a phenomenological framework for examining the dependence of effective fission delay times on fissility and N/Z. Also the present extracted fission delay times from excess pre-scission neutron multiplicities were interpreted in conjunction with the previously measured ER behaviour.
We describe the data analysis methods and the characteristics of the combined set-up of the γ -ray tracking spectrometer AGATA with two annular double sided silicon strip detectors (DSSD) (4” diameter) placed 5.65 cm upstream and downstream of the target, for the measurement of γ -light particle coincidences in near- and sub-barrier heavy-ion fusion reactions. The DSSD cover the angular ranges θ _lab=139.6^o – 162.7^o and =23.0^o – 40.4^o , corresponding to a total solid angle ≃ 26% of 4 π . The ohmic side of the DSSD is turned towards the target, so protons and α particles can be clearly identified. We show the relevant results obtained for the two systems ^28 Si+ ^12 C and ^16 O+ ^12 C down to very small cross sections in the tenths of nb range. Particle identification allows us to observe well-separated groups of protons and α ’s populating low-energy levels of the various fusion-evaporation residues (ER). Relative fusion cross sections are obtained with a procedure described in detail, and the absolute cross section scale is fixed by complementary measurements using an electrostatic beam deflector set-up where the ER are directly detected down to a few b. The AGATA+DSSD set-up is subject to significant improvements thanks to the scheduled increase of the number of γ detectors, and to the possibility of installing silicon detector arrays covering a larger solid angle. This will open the possibility of measuring fusion cross sections near, and possibly below, 1nb.
At scission, a highly deformed nucleus splits into two fragments that can sometimes be accompanied by emission of a third, much lighter, partner. Experimentally, proton and alpha emission at times close to scission has been observed but scission neutrons have not been clearly identified so far. In this study, we focus, using a theoretical microscopic model, on the emission of neutrons at the moment of scission of ^252 Cf. For this, approximate description of the scission process is proposed based on the solution of the bi-dimensional stationary Schrödinger equation, for the most probable mass division of ^252 Cf(sf): A_L/A_H = 109/143 . It considers a diabatic coupling between the neutron degree of freedom and the sudden changing neutron-nucleus potential during the scission process which is supposed to start when the radius of the neck separating the two fragments is ≈ 2 fm. The physical quantities analyzed in this work reveal that scission neutrons have specific characteristics. These neutrons are mainly emitted from the neck region. The sudden approximation used gives, for ^252 Cf, an upper limit for the scission neutron multiplicity of 0.89 and 0.91 n/fission, depending on the type of neutron correlation considered (Independent or BCS). They should represent, at most, a quarter of the total prompt neutrons (3.69 n/fission) observed experimentally. Furthermore, the mean kinetic energy distribution of scission neutrons reveals the presence of a long high-energy tail extending far beyond the limit of evaporated neutrons. This study thus highlights a potential signature of the scission neutron component of prompt fission neutrons.
Proton pickup and stripping reactions induced by ^48Ca projectiles on a ^197Au target have been investigated at a bombarding energy of 400 MeV. Projectile-like fragments were identified through measurements of their nuclear charge, angular distributions, and kinetic energy spectra. Cross sections were determined for reaction products with Z = 12-28. The measured energy and angular distributions reveal the coexistence of predominantly quasi-elastic-like (QE-like) and deep-inelastic-collision-like (DIC-like) components. Comparison with GRAZING and dinuclear system (DNS) calculations shows that the QE-like component is reasonably reproduced within the semiclassical GRAZING approach, while the broader charge distributions associated with the DIC-like dissipative component are described within the dinuclear system model.
The elastic and inelastic scattering of the weakly bound ^6Li+^9Be system at the laboratory energy of 32 MeV were studied within the optical model and coupled-channels approaches by taking into account the cluster structure of the interacting nuclei. The semi-microscopic double-folding optical potential was constructed using realistic nuclear matter densities obtained within the three-body cluster models ^6Li=α +p+n and ^9Be=α +α +n . The calculated folding potential was first validated through the analysis of the elastic scattering angular distributions and showed good agreement with the available experimental data. The inelastic scattering corresponding to the excitation of the ^9Be nucleus to the 2.43 MeV state was analyzed within the coupled-channels framework, with particular focus on the role of transition form factors. Three different transition form factors were considered and compared: the microscopic form factor calculated within the three-body α +α +n model of ^9Be , the form factor obtained as the first derivative of the calculated double-folding potential, and the phenomenological form factor taken as the first derivative of the Woods–Saxon potential. The microscopic three-body and double-folding form factors are demonstrated to be applicable to the description of inelastic scattering, yielding results comparable to those obtained with the phenomenological approach.
Exceptionally low values of the ratio of electric quadrupole transition rates, B_4/2≡ B(E2;4^+_1→ 2^+_1)/B(E2;2^+_1→ 0^+_gs)<1 , have been observed in neutron-deficient nuclei near N≈ 94 (W, Os, Pt) and N≈ 62 (Te, Xe) with few and comparable numbers of valence nucleons outside closed shells. Remarkably, the suppressed B_4/2 ratios coincide with low-lying energy level patterns characteristic of collective motion. Standard approaches, including large-scale shell model, collective models, and density functional theory, fail to reproduce this behavior, commonly referred to as the B_4/2 (or B(E2)) anomaly. Recent work has reproduced the effect in selected Pt and Os isotopes via mapping a triaxial rotor Hamiltonian onto the interacting boson model (IBM), attributing it to triaxial rotational motion. However, this interpretation is unexpected as collectivity typically emerges first through vibrational modes with increasing valence nucleon number along isotopic chains. Here, we address this discrepancy using an extended IBM Hamiltonian across nuclei exhibiting the anomaly, benchmarked against large-scale shell model calculations, and propose that the B(E2) anomaly arises from a low-lying mixed-symmetry collective mode that bridges single-particle and collective dynamics.
