Background: The influence of halo structure of He-6, B-8, Be-11, and Li-11 nuclei in several mechanisms such as direct reactions and fusion is already established, although not completely understood. The influence of the C-10 Brunnian structure is less known. Purpose: To investigate the influence of the cluster configuration of C-10 on the elastic scattering at an energy close to the Coulomb barrier. Methods: We present experimental data for the elastic scattering of the C-10 + Pb-208 system at E-lab = 66 MeV. The data are compared to the three- and the four-body continuum-discretized coupled-channels calculations assuming B-9 +p, Be-6 +alpha, and Be-8 +p + p configurations. Results: The experimental angular distribution of the cross sections shows the suppression of the Fresnel peak that is reasonably well reproduced by the continuum-discretized coupled-channels calculations. However, the calculations underestimate the cross sections at backward angles. Couplings to continuum states represent a small effect. Conclusions: The cluster configurations of C-10 assumed in the present work are able to describe some of the features of the data. To explain the data at backward angles, experimental data for the breakup and an extension of theoretical formalism towards a four-body cluster seem to be in need to reproduce the measured angular distribution.

\textbf{Background:} The influence of halo structure of $^6$He, $^8$B, $^{11}$Be and $^{11}$Li nuclei in several mechanisms such as direct reactions and fusion is already established, although not completely understood. The influence of the $^{10}$C Brunnian structure is less known. \textbf{Purpose:} To investigate the influence of the cluster configuration of $^{10}$C on the elastic scattering at an energy close to the Coulomb barrier. \textbf{Methods:} We present experimental data for the elastic scattering of the $^{10}$C+$^{208}$Pb system at $E_{\rm lab}$ = 66~MeV. The data are compared to the three- and the four-body continuum-discretized coupled-channels calculations assuming $^9$B+$p$, $^6$Be+$\alpha$ and $^8$Be+$p$+$p$ configurations. \textbf{Results:} The experimental angular distribution of the cross sections shows the suppression of the Fresnel peak that is reasonably well reproduced by the continuum-discretized coupled-channels calculations. However, the calculations underestimate the cross sections at backward angles. Couplings to continuum states represent a small effect. \textbf{Conclusions:} The cluster configurations of $^{10}$C assumed in the present work are able to describe some of the features of the data. In order to explain the data at backward angles, experimental data for the breakup and an extension of theoretical formalism towards a four-body cluster seem to be in need to reproduce the measured angular distribution.

The incomplete fusion cross section of the 6Li + 28Si weakly bound system at above barrier energies was deduced from the measured \( \gamma\)-ray cross sections. The complete fusion cross section was estimated from the measured total fusion and incomplete fusion cross section and is found to be 85-100% of the total fusion cross section. The coupled channel calculation has been performed considering ground and first excited states of 28Si target. The fusion cross section estimated from coupled channel calculation shows good agreement with measured total fusion cross section at higher energies. The suppression of about 15% of the fusion cross section predicted by coupled channel calculation shows good agreement with the complete fusion cross section. The effect of the channel couplings on the elastic scattering angular distribution is also investigated.

Elastic scattering angular distributions for 6Li+[Formula: see text]Si system were measured at [Formula: see text] and analyzed along with the existing data from the previous measurements in the energy range of [Formula: see text]. The measured cross-sections and the existing data, forming a set of angular distributions over a range of E/[Formula: see text], were analyzed using the phenomenological optical model potential (OMP). Three different sets of potential parameters were used. The energy dependence of the real and the imaginary potential strengths were, subsequently, extracted at the radius of sensitivity ([Formula: see text]) for the system. Continuum Discretized Coupled Channel (CDCC) calculation was performed to explore the contribution of projectile break-up (BU) on the observed energy dependence of the effective potential for elastic scattering of 6Li from [Formula: see text]Si. The energy variation of the strength of the real potential with continuum coupling was found to agree with the energy dependence of the same extracted from the (OMP) analysis at energies around the barrier. But the behavior of the imaginary strength appeared to be different. The calculated fusion cross-sections, including the effect of BU, clearly overestimated the measured fusion excitation function data in the below and near barrier energies but compared well with the data at higher energies.

The Al-26 radioisotope is of great importance for understanding the chemical and dynamical evolution of our galaxy. Among the possible stellar sources, massive stars are believed to be the main producer of this radioisotope. Understanding Al-26 nucleosynthesis in massive stars requires estimates of the thermonuclear reaction rates of the Al-26(n, p)Mg-26, Al-26(n, alpha)Na-23, and Na-23(alpha, p)Mg-26 reactions. These reaction rates depend on the spectroscopic properties of Al-27 states above the neutron and alpha thresholds. In this context, the Al-27(p, p')Al-27* reaction was studied at 18 MeV using a high-resolution Enge Split-Pole spectrometer. States from the ground state up to excitation energies of approximate to 14 MeV were populated. While up to the Na-23 + alpha threshold no additional states are observed, we report for the first time 30 new levels above the Na-23 + alpha threshold and more than 30 new states above the Al-26 + n threshold for which excitation energies are determined with an uncertainty of 4-5 keV.

The fusion excitation and elastic angular distribution were measured for 6,7Li+28Si from below to above Coulomb barrier (≤ 3Vb) energies. The barrier distribution derived from the fusion data was found to be broad and asymmetric at the sub-barrier region, compared to 1D BPM estimation. Effect of rotational coupling on fusion was found to be not so dominant. Phenomenological optical potential parameters, with surface and volume type imaginary potentials, were obtained from f tting of elastic scattering data and energy dependence of real and imaginary surface strengths were investigated around the barrier. CDCC calculations considering only breakup of projectile were performed for 6,7Li+28Si with the elastic scattering data, using the code FRESCO. The effects of breakup of projectile on elastic cross section do not agree with the energy dependence of real and imaginary strength with volume type imaginary potential around the barrier.

Fusion excitation functions are measured for the system 6Li + 28Si using the characteristic \( \gamma\) -ray method, encompassing both the sub-barrier and above-barrier regions, viz, E lab = 7-24 MeV. Two separate experiments were performed, one for the above-barrier region ( E lab = 11-24 MeV) and another for the below-barrier region ( E lab = 7-10 MeV). The results were compared with our previously measured fusion cross-section for the 7Li + 28Si system. We observed the enhancement of the fusion cross-section at sub-barrier regions for both 6Li and 7Li , but the yield was substantially larger for 6Li . However, for well-above-barrier regions, a similar type of suppression was identified for both the systems.

The sub-barrier fusion excitation functions are measured for the first time for the system Li-7 + Si-28 by the characteristic gamma-ray method in the energy range E-lab = 7-11.5 MeV. The results show an enhancement, below the barrier, by about a factor of two when compared with the one-dimensional barrier penetration (1D BPM) model. Introduction of coupling with the rotational 2(+) state (1.779 MeV) of the target improves the fit somewhat, but still an enhancement of about 25-40% remains.

Excitation functions for the above-barrier fusion cross sections are measured for the first time for the $^{7}\mathrm{Li}+^{28}\mathrm{Si}$ system by two methods---the characteristic \ensuremath{\gamma}-ray method and the evaporation \ensuremath{\alpha} measurement method---in the energy range ${E}_{\mathrm{lab}}=11.5\text{\ensuremath{-}}26$ MeV. Experimental results are consistent and agree with each other, and the one-dimensional Barrier Penetration Model (BPM) predictions describe the data well up to twice the Coulomb barrier, but they overestimate the data by about 15--20% at higher energies.

Excitation functions for the above-barrier fusion cross sections are measured for the first time for the Li-7+Si-28 system by two methods-the characteristic gamma-ray method and the evaporation alpha measurement method-in the energy range E-lab=11.5-26 MeV. Experimental results are consistent and agree with each other, and the one-dimensional Barrier Penetration Model (BPM) predictions describe the data well up to twice the Coulomb barrier, but they overestimate the data by about 15-20% at higher energies.