Elastic scattering of the weakly bound nucleus Li-8 from the medium-mass target V-51 has been investigated at incident energies of 18.5 and 26 MeV. The projectile is described within a two-body cluster model consisting of a Li-7 core and a valence neutron. Experimental angular distributions are analyzed using phenomenological optical-model potentials, microscopic double-folding potentials based on the S & atilde;o Paulo potential (SPP2) and the density-dependent CDM3Y6 interaction, as well as a cluster-folding approach that explicitly incorporates the Li-7+n structure of the projectile. The calculated results show that all models provide a reasonable description of the measured data at forward angles, while larger differences appear at intermediate and backward angles. The cluster-folding calculations predict enhanced reaction cross-sections, reflecting the influence of the weak binding and extended spatial distribution of the valence neutron. The present analysis emphasizes the role of cluster degrees of freedom in reactions involving neutron-rich weakly bound nuclei and provides additional insight into the scattering dynamics of the Li-8+V-51 system.
The elastic scattering of the weakly bound nuclei 6 Li and 7 Li from the [Formula: see text]Al target at energies near the Coulomb barrier is analyzed using the Ginocchio potential within the optical-model framework, in place of the conventional Woods–Saxon form. Because the real and imaginary components of this potential share a common analytic kernel, their fitted surface-region strengths, [Formula: see text] and [Formula: see text], are intrinsically coupled through a single energy-dependent relation, allowing the breakup threshold anomaly (BTA) to be diagnosed directly from the fit without the need for an explicit dynamic polarization potential. A dimensionless anomaly parameter, [Formula: see text], is introduced to convert this coupling into a single quantitative measure of anomalous behavior at each bombarding energy. cOneFor 7 Li + [Formula: see text]Al, [Formula: see text] dips toward zero and [Formula: see text] shows a pronounced spike at [Formula: see text] MeV, at the Coulomb barrier. A [Formula: see text]-profile analysis of the 8.0 MeV angular distribution measured with experimental uncertainties gives [Formula: see text] ([Formula: see text]), about seven times its high-energy plateau, and a global re-analysis in which the potential geometry is also refitted gives [Formula: see text] ([Formula: see text]: 2.9–16.5); values at or below the anomaly threshold are excluded at more than [Formula: see text]. The much larger peak-to-plateau ratio ([Formula: see text]) obtained from a fit in which the real depth nearly vanishes illustrates the sensitivity of this ratio to the fit assumptions and is not a measure of the size of the anomaly. cThreeIn the re-analysis the enhancement is confined to the 8.0 MeV point. cFiveFor 6 Li + [Formula: see text]Al, the fit with cAuththe original geometry gives a minimum of [Formula: see text] and a maximum of [Formula: see text] near 8 MeV, with [Formula: see text] peaking at 2.7 times its plateau value over 8–12 MeV; in the global re-analysis [Formula: see text] at 10 and 12 MeV is close to the plateau, and the largest value occurs at cAuth7.0 MeV, below the barrier, as expected for the BTA. Both systems are reproduced with an energy-independent imaginary-to-real strength ratio cAuth[Formula: see text] [Formula: see text] cAuthwith the original geometry (16–24% in the global re-analysis), substantially below the 30–150% typically required in Woods–Saxon analyses, thereby preserving the diffractive oscillatory structure characteristic of light projectile–target systems. cThreeThe results cAuthsupport the BTA found for 6 Li + [Formula: see text]Al in earlier analysescAuth, with an anomaly window whose energy extent depends on the potential geometry, and identify for 7 Li + [Formula: see text]Al a statistically significant, energy-localized enhancement of the BTA type at the barrier, refining earlier Woods–Saxon-based conclusions cAuththat the conventional TA is absent for this system and indicating that the anomaly on this target is governed mainly by the projectile’s breakup threshold and cluster structure.
The experimental dependencies of the average values of the multiplicity, transverse and total momenta, longitudinal rapidity, cosine of emission angle of the negative pions on the average transverse momentum of leading protons in p+ 12 C collisions at incident momentum of 9.9 GeV/c have been investigated. Average fraction (⟨ΔT/T 0 ⟩) of the incident proton energy, transferred to the target 12 C nucleus, has been studied as a function of the transverse momentum of the leading proton in events containing a leading proton in p+ 12 C collisions at 9.9 GeV/c. The experimental data have been compared systematically with numerical calculations performed using the modified FRITIOF model. The FRITIOF model has reproduced satisfactorily the experimental dependencies of the transverse and total momenta, and longitudinal rapidities of the negative pions on the average transverse momentum of leading protons. The model has underestimated significantly the average multiplicity of the negative pions and ⟨ΔT/T 0 ⟩ in p+ 12 C collision events with leading protons. The experimental values of ⟨ΔT/T 0 ⟩ have demonstrated significant dependence on the average transverse momentum of leading protons in contrast to the very weak dependence obtained for this parameter in the model.
The structural evolution and electromagnetic properties of the even-even N = 52 isotonic chain ([Formula: see text] were investigated using the Interacting Boson Model with one boson species (IBM-1) and its proton-neutron extension (IBM-2). Lying just above the robust N = 50 shell closure, this chain offers a sensitive testing ground for the onset of collectivity and the role of proton-neutron correlations as Z increases from 40 to 46. A total boson number [Formula: see text] = 3-6 is used to describe the low-lying collective states. Calculated energy spectra reproduce the experimental level schemes with good accuracy, yielding [Formula: see text] ratios of 1.6-1.8, consistent with the predominantly vibrational U(5)-like character. The central focus is a systematic IBM-1/IBM-2 comparison quantifying the proton-neutron correlations along the chain. Treating proton and neutron bosons explicitly clearly improves the description of excitation energies: the root-mean-square deviation drops from 167-246 keV (IBM-1) to 22-154 keV (IBM-2), an average reduction of approximately 21%. A consistent increase in the coefficient of determination R 2 corroborates the superior predictive power of IBM-2. Furthermore, IBM-2 predicts mixed-symmetry states, notably the lowest [Formula: see text] mixed-symmetry levels, which are absent in IBM-1. These states show enhanced magnetic dipole transition strengths of up to 0.23 [Formula: see text], providing direct spectroscopic signatures of proton-neutron degree-of-freedom effects. These results underscore the essential role of explicit proton-neutron interactions in capturing the emergence of collectivity just above the N = 50 shell closure.
The main goal of this work is to determine the values of the asymptotic normalization coefficients for [Formula: see text]. For this purpose, differential cross-sections for the proton transfer [Formula: see text]Mg( 3 He,d)[Formula: see text]Al and [Formula: see text]Mg( 7 Li, 6 He)[Formula: see text]Al reactions at the energies 25[Formula: see text]MeV and 31.5[Formula: see text]MeV were analyzed within the Modified Distorted-Wave Born Approximation method. New values of the asymptotic normalization coefficients for the [Formula: see text] configuration were obtained.
