Narrow Results

We have measured the angular distributions for ¹⁶O elastically scattered on ¹²C nuclei at energy 28 MeV and also for ¹²C ion beam elastically scattered on ¹¹B target nuclei at energy 18 MeV. These measurements were performed in the cyclotron DC-60 INP NNC RK. Calculations were performed using both empirical Woods–Saxon and double folding optical model potentials. Both elastic scattering and transfer reaction were taken into consideration. We have extracted the spectroscopic factors for the configurations ¹⁶O → ¹²C + α and ¹²C → ¹¹B + p and compared them with other calculated or extracted values at different energies from literature. The extracted spectroscopic factor for the configuration ¹²C → ¹¹B + p from the current work is in the range 2.7–3.1, which is very close to Cohen–Kurath prediction. While for the configuration ¹⁶O → ¹²C + α, spectroscopic factors show fluctuation with energy which could be due to the well-known resonant-like behavior observed in ¹⁶O + ¹²C excitation function.

The angular distribution measurements for ¹⁶O ion beam elastically scattered from ¹¹B target of thickness 32.9μg/cm² at energy 22.4 MeV had been performed in the cyclotron DC-60 INP NNC RK. The previous measurements for ¹⁶O+¹¹B nuclear system at energies 27, 30, 32.5 and 35 MeV showed an increase in the differential cross-section at backward angles due to the contribution of cluster transfer. Such transfer process could not be described in terms of optical model (OM); it could be described within the framework of distorted wave Born approximation method implemented in FRESCO code. Both one (⁵Li) and two-step transfer (proton transfer followed by Alpha transfer) were taken into considerations. We have extracted the spectroscopic amplitude (SA) for the configuration ¹⁶O→¹¹B+⁵Li.

The $(\mathrm{\text{p}},\mathrm{\text{2p}})$ reaction on ${}^{40}\mathrm{\text{Ca}}$ at incident proton energy of 300MeV is examined in the formalism of finite-range relativistic distorted-wave impulse approximation (FR-RDWIA). In comparison to conventional t-matrix model of Love–Franey, a new form of nucleon–nucleon t-matrix effective interaction is derived at 300MeV using Reid soft core potentials for isotopic spin one and taking into account the finite-range effects in the $\mathrm{\text{p}}-\mathrm{\text{p}}$ interaction at knockout vertex. In comparison to the conventional finite range nonrelativistic and relativistic formalism, the present formalism with a new version of $\mathrm{\text{p}}-\mathrm{\text{p}}$ t-matrix is effectively reproducing the shape of cross-section energy distributions for ${\mathrm{\text{1d}}}_{3/2}$, ${\mathrm{\text{1d}}}_{5/2}$ and ${\mathrm{\text{2s}}}_{1/2}$ states for asymmetric angle pair of $30^{\circ }$–$55^{\circ }$. Discrepancies between the experimental cross-section data and finite range theoretical calculations at ${\mathrm{\text{E}}}_p=300$MeV are reasonably resolved in the present approach. Without any adjustable parameter of bound state, the obtained spectroscopic factors are in reasonably good agreement with the relativistic and nonrelativistic theoretical predictions by $(\mathrm{\text{p}},\mathrm{\text{2p}})$, $(\mathrm{\text{e}},{\mathrm{\text{e}}}^{\prime }\mathrm{\text{p}})$ and $(\mathrm{\text{d}},{}^3\mathrm{\text{He}})$ analysis.

The reaction ${}^{27}$Al($d$,³He) at 25 MeV beam energy has been utilized to study the states in even–even nucleus ${}^{26}$Mg. The spectroscopic factors have been extracted for the states of ${}^{26}$Mg up to 7.50MeV excitation energy using local, zero-range distorted wave Born approximation. The extracted spectroscopic factors have been compared with the previously reported values. The present results were also compared with the predictions from a theoretical shell model and rotational model.

The spectroscopic factor (SF) of doubly-magic nuclei, neutron shell closed and neutron-rich nuclei has been determined through ($d$, $p$) reaction in the projectile energy range from 3 to 26MeV. The theoretical angular differential cross-sections of ($d$, $p)$ reactions in scattering center-of-mass angles from $0^{\circ }$ to $60^{\circ }$ have been calculated using FRESCO and NRV-DWUCK5 codes. By comparing the theoretical angular differential cross-sections with available experimental angular differential cross-sections, the values of SF have been determined. The exponential increase of SF as a function of neutron separation energy normalized by spin of the recoil nuclei has been shown for the first time for doubly-magic nuclei. The similar type of trend has also been observed for neutron-rich as well as neutron shell closed nuclei as a function of neutron separation energy normalized by asymmetric factor of recoil nucleus. More experimental data are required to verify the trend predicted by this investigation.

Asymptotic normalization coefficients (ANCs) and spectroscopic factors (SFs) for proton binding in the ground states of the ${}^{15}$N, ${}^{16}$O, ${}^{19}$F and ${}^{32}$S nuclei were extracted from an analysis of available literature data on the (³He$,d$) and ($n,d$) reactions. Modified DWBA and ADWA analyses showed that the proton transfer process is more peripheral in (³He,d) reactions and therefore more reliable for determining the ANCs. As a result of the comparative analysis of peripheral (³He,d) and nonperipheral ($n,d$) reactions, the uncertainties in the extracted values of SFs were reduced. The data obtained are to be used in calculating astrophysical S-factors for radiative proton capture.

The present contribution focuses on three recent experimental achievements obtained at the GANIL facility on the study of the N = 28 shell closure south to the doubly magic nucleus . First, the single particle energies of the neutron fp states in ⁴⁷Ar have been determined by transfer (d,p) reaction using a radioactive beam of . A reduction of the N = 28 gap and of the SO splittings of the f and p states is found. Second, an E0 isomer has been discovered in which is suggestive of a shape mixing. Third, the energy of the first 2⁺ state of has been obtained through in-beam γ-ray emission induced by a 2 protons knock-out reaction. Its low value, 770(19) keV, points to a large deformation there. The gradual change from spherical to deformation in the N = 28 isotones from Z = 20 to Z = 14 is ascribed to specific proton-neutron interactions and to enhanced quadrupole correlations. A global description of all the physics involved at N = 28 is derived along with experimental results.

The observation of ²⁶Al is an useful tool for γ-ray astronomy and in studies of galactic chemical evolution. The most likely mechanism for ²⁶A1 nucleosynthesis is in the hydrogen burning MgAl cycle, and the ²⁶A1 production from the ²⁵Mg(p, γ)²⁶Al reaction at the important temperature range below T = 0.2 is still not well known. We present a proposal to measure the resonance strength of 58 keV resonance level of the ²⁵Mg(p, γ)²⁶Al reaction, and the effective counting rate is estimated for the direct measurement at Jinping underground laboratory.