The ^8Li(n,γ)^9Li reaction is considered significant for the synthesis of nuclei beyond the A=8 stability gap in inhomogeneous big-bang nucleosynthesis models, as well as in r-process nucleosynthesis scenarios. However, direct measurement of this reaction is precluded by the short half-life of ^8Li and the absence of a neutron target. Consequently, existing reaction rate estimates based on indirect experimental methods and theoretical calculations differ by orders of magnitude. In the present work, the ^8Li(n,γ)^9Li neutron-capture cross section and the corresponding thermonuclear reaction rate are evaluated within a phenomenological R-matrix framework, including both non-resonant direct capture (DC) and resonant capture through the 5/2^- state at E_x = 4.30 MeV. The uncertainties associated with the R-matrix input parameters are propagated using Monte Carlo sampling, while the sensitivity to the channel radius is treated as an R-matrix model uncertainty. The effective total uncertainties in the calculated cross sections and reaction rates are obtained by adding these two uncertainty contributions in quadrature. We obtain a total capture rate of 983.9^+410.9_-261.5 cm^3 mol^-1 s^-1 at T = 1 GK, with DC dominating at low temperatures (T=0.01-0.4 GK) and the 5/2^- resonance at higher temperatures (T=0.5-5 GK). The present results are consistent with the upper limit of Kobayashi et al. , which previous theoretical predictions exceed by factors of 3-50.

The low-lying level structure of 80Se was investigated via the 76Ge(9Be,2p3n) reaction at Elab ≈ 31 MeV using a Compton-suppressed HPGe clover array, and level lifetimes were measured with the Doppler-shift attenuation method. Measured excitation energies and B(E2) transition strengths are reasonably well reproduced by Interacting Boson Approximation (IBA) calculations. The observed excitation-energy and transition-strength patterns associated with the σ=5 and σ=3 representations, together with candidate members of the σ=1 representation, exhibit pronounced O(6)-like collective behavior in this five-boson system. The combined experimental observables and finite-boson IBA calculations indicate a surprisingly good correspondence with O(6) expectations for these selected collective structures. At the same time, the presence of low-lying 02+ and 23+ states that are not consistently accommodated within the same classification, together with a finite B(E2;03+→21+) strength, demonstrates that the O(6) limit does not provide a complete description of the low-energy spectrum. We therefore interpret the present results as evidence for pronounced O(6)-like collective structures embedded within a more complex nuclear structure of 80Se.

Low-and intermediate-spin negative-parity band structures have been investigated in the 82Kr nucleus using the fusion-evaporation reaction 76Ge (9Be, 3n) at ELab approximate to 31 MeV. Lifetimes of the states of interest in 82Kr have been measured using the Doppler shift attenuation method with the help of the Indian National Gamma Array, and the parity of the states has been confirmed from polarization measurements. The deduced B(M1) and B(E2) values from the lifetime measurements in comparison with the particle rotor model and the total Routhian surfaces calculations reveal that the bands DB1 and DB2 are based on the collective oblate and prolate deformed core, respectively. The enhanced electric dipole strengths, B(E1)s, and dipole moments, |D0|s, for the parity-changing transitions connecting the negative-parity bands DB1 and DB2 to the ground-state positive-parity band QB1 ensure the octupole correlation in 82Kr.

The elastic scattering angular distributions of the tightly bound 11B on the 89Y target, at bombarding energies in the vicinity of the Coulomb barrier have been measured. The energy dependence of the interaction potential was analyzed using the Woods-Saxon potential (WSP) and São Paulo potential (SPP). Both models confirmed the presence of the typical threshold anomaly. To account for varying sizes and Coulomb barriers, the total reaction cross sections for the current and similar mass-range systems were gathered from literature and reduced. This normalization allows for a direct comparison by eliminating trivial effects arising due to different sizes and different Coulomb barriers. To quantify how direct reaction channels affect the total reaction cross section, one-channel calculations, that account only for fusion, were performed for all systems. These calculations isolate the fusion process to highlight the specific impact of the direct channels. By applying the reduction procedure, it is concluded that there is absence of the breakup channel but other possible channels like inelastic, transfer etc. are present.

The reaction rates of 22Ne(alpha, n)25Mg and its competing channel 22Ne(alpha, gamma)26Mg control the production of neutron flux for weak s-process nucleosynthesis in low mass asymptotic giant branch stars and in massive stars with M >= 10M circle dot. The temperature range of interest for these reactions lies between 0.2 and 0.4 GK. However, the rates of these reactions are poorly constrained at these temperatures due to uncertainties in the nuclear properties of several resonance states in the compound nucleus 26Mg, lying within the Gamow window. The present work reports a full R-matrix evaluation of the 22Ne(alpha, n)25Mg and 22Ne(alpha, gamma)26Mg reaction rates using updated nuclear data of 26Mg states. Previous rate evaluation by Adsley et al and R-matrix calculations of Wiescher et al were limited by using narrow resonance approximations and omission of the resonances below Er = 705 keV, respectively. In this work, the R-matrix fit to the available 22Ne(alpha, n)25Mg reaction data is performed by including the contributions of previously neglected resonances below Er = 705 keV and considering the interference effects. The (alpha, n) reaction rate from the present R-matrix evaluations is noticeably higher than the narrow resonance approximation calculations in the temperature range 0.1-0.3 GK. In particular, the present (alpha, n) reaction rate is significantly higher (7.5 - 4.5 times) compared to Adsley et al at 0.2-0.3 GK and approximate to 2 times greater than Wiescher et al at 0.3 GK. The estimated reaction rate ratio of (alpha, n) to (alpha, gamma) in the relevant temperature window 0.2-0.8 GK indicates that the production of neutrons for the s-process is more likely than the radiative alpha capture reaction, compared to the previous estimate by Adsley et al.

The $γ$-ray strength function of medium-mass neutron rich nuclei $^{72}$Ga has been extracted from the statistical Hauser-Feshbach analysis of the available capture data of $^{71}\mathrm{Ga}(n,γ){}^{72}\mathrm{Ga}$ over the 0.01 - 3 MeV energy range with the required nuclear level density (NLD) of the $^{72}$Ga constraint from the work of R. Santra et al.,[\href{https://doi.org/10.1103/PhysRevC.107.064611}{Physical Review C 107, 064611 (2023)}]. The Gogny D1M model for the E1 and M1 strength functions, including low-energy upbends of $^{72}$Ga nuclei, is experimentally constrained in the present work. Subsequently, the Maxwellian-averaged cross section(MACS) of $^{71}\mathrm{Ga}$ has been reevaluated based on the present $γ$-ray strength function. It is found that the present MACS value at \(kT = 30\) keV is 115.35$^{+11.92}_{-10.44}$ mb, which is consistent with previous work.

Low-lying states in ^54 Cr have been investigated via the α -transfer reaction ^50 Ti( ^7 Li,t) at a bombarding energy of 20 MeV. The exclusive α -transfer channel is separated from other reaction channels through the appropriate energy gate on the complementary particle, triton. Levels of ^54 Cr populated exclusively by the α -transfer process could be identified up to ≈ 5 MeV excitation energy and angular momentum up to (8)^+ , by identifying the corresponding known γ -rays. These include multiple low-lying non-yrast 2 ^+ and 4 ^+ states, which would otherwise be unfavorable via fusion evaporation reactions. The feeding-subtracted γ -ray yields have been extracted to estimate the population of various excited states through the transfer process. The measured integrated transfer cross sections for all the observed yrast and non-yrast states are compared with Coupled Channels calculations using fresco to extract the α + ^50 Ti core spectroscopic factors. For the yrast states, a higher α +core overlap is seen for the 2^+ and 4^+ states, while it is seen to be less favorable for the 6^+ and (8)^+ states when α -transfer is considered to occur predominantly as a direct one-step process to the ^50 Ti core ground state. The yrast 2^+ , and 4^+ states are predominantly populated by single-step transfer, while for the states with spin ≥ 5, the possibility of core excitation followed by α -transfer shows a larger α -core overlap. For the non-yrast 0^+ , 2^+ , and 4^+ states, single-step transfer shows moderate to small α -core overlap. No higher spin non-yrast states are observed.

The present study unfolds the relative importance of N/Z, shell effects, and thermal fluctuations in shaping the temperature dependence of the isovector giant dipole resonance (IVGDR) width. To this end, we measured the γ-ray spectra from excited Zn62,68 populated through 4He+58,64Ni reactions at beam energies of 28 MeV and 40 MeV, and compared the corresponding IVGDR widths with those for nuclei close to the doubly magic 56Ni and moderately away from it. The large-area modular BaF2 detector array was used to detect high-energy γ rays (Eγ>4 MeV). The Bayesian inference approach was combined with the statistical model analysis to extract the IVGDR parameters from the measured spectra. Calculation of IVGDR widths was performed using various theoretical approaches, specifically the thermal shape fluctuation model (TSFM) with microscopic energy density functional inputs. TSFM calculation was also performed using the free energy surfaces from the deformed liquid drop model. For 68Zn, the width is observed to increase closely following the TSFM prediction. In contrast, suppression of the width is noticed for 62Zn at low temperatures, similar to other nearby nuclei with N and/or Z closer to 28. Moreover, 68Zn indicates an early onset of the saturation in the IVGDR width, mimicking structural changes appropriately comprehended by the microscopic calculations. These findings suggest that the relative influence of microscopic effects and thermal broadening in the IVGDR width is strongly governed by the proximity of the decaying nucleus to magicity.

Positive parity band structures in 82Kr were investigated using the reaction 76Ge(9Be, 3n) at ELab approximate to 31 MeV with the help of the Indian National Gamma Array. The predominant E2 component of the AI = 1 band interlinking transitions and the decreasing nature of wobbling energy with spin were observed for the bands TW1 and TW2, reflecting their transverse wobbling character. The absolute B(E2) transition strengths of the zeroth and first phonon wobbling bands as well as the signature partner band were extracted from the lifetime measurements. The extracted B(E2) values in comparison with the triaxial projected shell model calculations confirm similar deformation for the three bands, which is an important characteristic of wobbling modes. This is conclusive evidence of transverse wobbling motion in an even-even nucleus based on a two-neutron configuration and also an observation of wobbling motion in the A approximate to 80 mass region.

The 3a reaction plays a crucial role in stellar nucleosynthesis, as it is responsible for synthesizing carbon from helium. This reaction overcomes the A = 5 and A = 8 mass gaps, allowing the synthesis of heavier elements in stars. Additionally, this reaction significantly influences the evolution of the first-generation stars, accreting white dwarfs, and neutron stars. The relevant temperature range spans from 0.01 to 10 GK. Prior rate evaluations of the sequential process [a+a-8Be(a, y)12C] have primarily focused on the uncertainties associated with the resonance parameters in 8Be and 12C states. Since direct measurement data for the 8Be(a, y)12C capture reaction is unavailable, the effect of interference between the direct (non-resonant) and resonance capture components of the 8Be(a, y)12C capture reaction remains uncertain in the sequential 3a path. In particular, previous studies have not taken into account the uncertainty arising from this interference effect. In this work, a phenomenological R-matrix model has been employed to analyze the required a+a scattering and the 8Be(a,y)12C capture excitation functions. The present rate evaluation method incorporates uncertainties from both interference effects and resonance/bound-state parameters, utilizing updated nuclear data on 12C. The revised 3a reaction rate exhibits significantly greater uncertainty than previous evaluations due to the inclusion of interference effects in the 8Be(a,y)12C reaction. Interference effects contribute approximately 75% to the total uncertainty. When considering only parameter uncertainties, the present rate aligns well with previous studies within the 0.1-2 GK temperature range. The present upper limits of the 3a rate are two orders of magnitude lower than the astrophysical limits.

Neutron energies and angular distributions were measured in 9 Be(a,n) 12 C reaction for a energies of 5.5 and 6.5 MeV. Three major neutron groups were observed in the spectrum, which correspond to the ground and first two excited states of 12 C. Measured data could only be explained by the TALYS calculation if reaction at more than one location within the target is considered for a given beam energy. The preferred locations are driven by the resonance energy levels existing in 13 C. Neutron yield due to the 9 Be breakup process was determined which is found to be 12.6 +/- 0.2% and 18.4 +/- 0.5% of the total reaction cross-section for 5.5 and 6.5 MeV respectively.

The 22Ne(p, gamma ) 23Na capture reaction is a key step in the Ne-Na cycle of hydrogen burning. The rate of this reaction is critical in classical novae nucleosynthesis and hot bottom burning (HBB) processes in asymptotic giant branch (AGB) stars. Despite its astrophysical importance, significant uncertainty remains in the reaction rate due to several narrow low-energy resonances lying within and near the Gamow window. The present work revisits this reaction by examining the contribution of the 8664 keV subthreshold state and the 8945 keV doublet resonance state of 7/2- configuration in 23Na. Finite range distorted-wave Born approximation (FRDWBA) analysis of existing 22Ne(3He, d) 23Na transfer reaction data was carried out to extract the peripheral asymptotic normalization coefficients (ANCs) of the 8664 keV state. The ANC value obtained in the present work is approximate to 25% higher compared to the previous work by Santra et al. [Phys. Rev. C 101, 025802 (2020)]. Systematic R-matrix calculations were performed to obtain the nonresonant astrophysical S factor utilizing the enhanced ANC value. The resonance strengths of the 8945 keV doublets were deduced from shell model calculations. The rate calculations are performed by omitting the resonances at Ex = 8862, 8894, and 9000 keV, which are unlikely to exist as reported by Carrasco-Rojas et al. [Phys. Rev. C 108, 045802 (2023)]. The total reaction rate is found to be approximate to 15-20% higher at temperatures relevant for the HBB processes, compared to the recent rate measured by Williams et al. [Phys. Rev. C 102, 035801 (2020)], and matches their rate at temperatures of interest for classical novae nucleosynthesis.

Neutron energies and angular distributions were measured in 9Be(α,n)12C reaction for α energies of 5.5 and 6.5 MeV. Three major neutron groups were observed in the spectrum, which correspond to the ground and first two excited states of 12C. Measured data could only be explained by the TALYS calculation if reaction at more than one location within the target are considered for a given beam energy. The preferred locations are driven by the resonance energy levels existing in 13C. Neutron yield due to the 9Be breakup process was determined which is found to 12.6 ± 0.2% and 18.4 ± 0.5% of the total reaction cross-section for 5.5 and 6.5 MeV respectively.

Temperature-dependent photon strength function (PSF) models, along with the widely accepted temperatureindependent Brink-Axel Lorentzian model, are investigated in their application to determine the properties of the giant dipole resonance (GDR) built on the excited states of nuclei up to a temperature approximate to 1.5 MeV. Three temperature-dependent models, namely, the simple modified Lorentzian model, the hybrid model by Goriely, and the generalized Lorentzian model of Kopecky and Uhl, are studied. The statistical model calculations with all PSF models reproduce the high-energy (E gamma approximate to 5-25 MeV) gamma -ray spectra originating from the decay of 62Zn and 201Tl compound nuclei reasonably well, and put forward approximately the same peak energy and strength of the GDR. Nevertheless, at a given temperature, significant variation is observed in the predicted GDR width, which may influence the theoretical models used to calculate the GDR width.

The radiative decay of the Hoyle state serves as the gateway to the production of heavier elements in a stellar environment. Here, we present an exclusive measurement of electric quadruple (E2) transitions of the Hoyle state to the ground state of 12C through the 12C(p, p′γγ)12C reaction. A triple coincidence measurement yields the radiative branching ratio Γrad/Γ = 4.01 (30) × 10−4. This result was corroborated by an independent experiment based on the complete kinematical measurement via 12C(p, p′)12C reaction, yielding a consistent result of Γrad/Γ = 4.04 (30) × 10−4. Combining our results with the currently adopted values of Γπ(E0)/Γ and Γπ(E0), the radiative width of the Hoyle state is determined to be 3.75 (40) × 10−3 eV. It is important to note that our finding do not align with a recently reported 34% increase in the radiative decay width of the Hoyle state but is consistent with the currently accepted value.

The quadrupole transition strength B ( E 2) deduced from the measured level lifetimes using the Doppler shift attenuation method with the help of the Indian National Gamma Array, decreases with increasing spin for the band of interest in 82 Kr. In addition, the ratio of the dynamic moment of inertia with the B ( E 2) value increases along the band. Large basis shell -model calculations have been performed to understand the microscopic origin of the band of interest. The experimental results are reproduced well by the numerical calculations within the framework of a semiclassical geometric model, which conclusively establish the antimagnetic rotation in the shape -phase transition point nucleus 82 Kr in the A approximate to 80 mass region. Present investigation represents the first conclusive evidence of an antimagnetic rotational band based on the valence protons and neutrons in the 1 g 9 / 2 orbitals in an atomic nucleus.

The $^{22}\mathrm{Ne}(p,\ensuremath{\gamma})^{23}\mathrm{Na}$ capture reaction is a key step in the Ne-Na cycle of hydrogen burning. The rate of this reaction is critical in classical novae nucleosynthesis and hot bottom burning (HBB) processes in asymptotic giant branch (AGB) stars. Despite its astrophysical importance, significant uncertainty remains in the reaction rate due to several narrow low-energy resonances lying within and near the Gamow window. The present work revisits this reaction by examining the contribution of the 8664 keV subthreshold state and the 8945 keV doublet resonance state of $7/{2}^{\ensuremath{-}}$ configuration in $^{23}\mathrm{Na}$. Finite range distorted-wave Born approximation (FRDWBA) analysis of existing $^{22}\mathrm{Ne}(^{3}\mathrm{He},d)^{23}\mathrm{Na}$ transfer reaction data was carried out to extract the peripheral asymptotic normalization coefficients (ANCs) of the 8664 keV state. The ANC value obtained in the present work is $\ensuremath{\approx}25%$ higher compared to the previous work by Santra et al. [Phys. Rev. C 101, 025802 (2020)]. Systematic $R$-matrix calculations were performed to obtain the nonresonant astrophysical $S$ factor utilizing the enhanced ANC value. The resonance strengths of the 8945 keV doublets were deduced from shell model calculations. The rate calculations are performed by omitting the resonances at ${E}_{x}=8862$, 8894, and 9000 keV, which are unlikely to exist as reported by Carrasco-Rojas et al. [Phys. Rev. C 108, 045802 (2023)]. The total reaction rate is found to be $\ensuremath{\approx}15--20%$ higher at temperatures relevant for the HBB processes, compared to the recent rate measured by Williams et al. [Phys. Rev. C 102, 035801 (2020)], and matches their rate at temperatures of interest for classical novae nucleosynthesis.

The $^{22}$Ne($p,\gamma$)$^{23}$Na capture reaction is a key member of the Ne-Na cycle of hydrogen burning. The rate of this reaction is critical in classical novae nucleosynthesis and hot bottom burning processes (HBB) in asymptotic giant branch (AGB) stars. Despite its astrophysical importance, significant uncertainty remains in the reaction rate due to several narrow low energy resonances lying near the Gamow window. The present work revisits this reaction by examining the contribution of the 8664 keV subthreshold state and the 151 keV doublet resonance state of 7/2$^-$ configuration in $^{23}$Na. Finite range distorted-wave Born approximation (FRDWBA) analyses of existing $^{22}$Ne($^3$He,$d$)$^{23}$Na transfer reaction data were carried out to extract the peripheral asymptotic normalization coefficients (ANC) of the 8664 keV state. The ANC value obtained in the present work is $\sim 25\%$ higher compared to the previous work by Santra et al.~\cite{SA20}. Systematic $R$-matrix calculations were performed to obtain the non-resonant astrophysical $S$-factor utilizing the enhanced ANC value. The resonance strengths of the 8945 keV doublets were deduced from shell model calculations. The total reaction rate is found to be $\sim 15\%$ higher at temperatures relevant for the HBB processes, compared to the recent rate measured by Williams et al.~\cite{WI20}, and matches the rate by Williams et al.~\cite{WI20} at temperatures of interest for classical novae nucleosynthesis.

The gamma -gated proton spectra measured in the reactions 64Ni(9Be, p2n) 70Ga and 64Ni(9Be, pn) 71Ga, have been utilized to probe the collective enhancement in nuclear level density (NLD) of two oblate deformed nuclei 71Ga and 72Ga. It is seen that the gamma -gated proton spectrum are reasonably explained by using the large value of the inverse level density parameter (k = 11.2 MeV) in the NLD prescription of the Fermi gas model. The large value of k indicates rotational enhancement, which is consistent with the earlier results in other mass regions. Furthermore, a rotational enhancement factor has been included in the NLD and used in the statistical model calculation keeping the systematic value of = 8.6 MeV. It explains the gamma -gated proton spectrum nicely, which indicates the presence of collective enhancement in the NLD. The extracted enhancement factors are found to be 8.0+/-2.0 and 5.5+/-1.0 and vanish at around 15, 18 MeV excitation energies for 71Ga, 72Ga, respectively. Present observations are consistent with the previous results obtained by Pandit et al. [Phys. Rev. C 97, 041301(R) (2018)] and Mohanto et al. [Phys. Rev. C 100, 011602(R) (2019)].