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Electronic structures of single crystalline black phosphorus were studied by state-of-the-art angle-resolved photoemission spectroscopy (ARPES). Through high resolution photon energy dependence measurements, the band dispersions along out-of-plane and in-plane directions are experimentally determined. The electrons were found to be more localized in the ab plane than is predicted in calculations. Beside the kz-dispersive bulk bands, a surface resonant state is also observed in the momentum space. Our results strongly suggest that more details need to be considered to fully understand the electronic properties of black phosphorus theoretically. [ABSTRACT FROM AUTHOR]

The proton decay of53Com(3174.1 keV, 19/2-) was investigated via the fragmentation of a 58Ni primary beam. The proton-decay energy was determined with an improved precision to be 1558(8) keV. With this new result and the mass of 53Com, the 52Fe mass excess was derived to be - 48330(8)keV, which is in good agreement with the AMEI2 value. A new recommended value of - 48331.6(49) keV is given. [ABSTRACT FROM AUTHOR]

The angular distributions of the 12C(11B,11B)12C and 12C(11B,12C)11B reactions have been measured at an incident energy of 50 MeV by using the high resolution Q3D magnetic spectrometer of the HI-13 tandem accelerator at China Institute of Atomic Energy, Beijing. The optical potential parameters of the 11B + 12C system are determined by fitting the angular distribution of the elastic scattering and then used to predict the cross sections of the elastic transfer reaction leading to the ground state in l 2C based on distorted-wave Born approximation (DWBA) analysis. Taking into account the interference between the elastic scattering and the elastic transfer processes, the proton spectroscopic factor of the, 12C ground state is extracted to be 2.15 ± 0.23 by constraining the geometrical parameters r0 and a using the rms radius of the valence proton in the 12C ground state. [ABSTRACT FROM AUTHOR]

All the 16F levels are unbound by proton emission. To date the four low-lying 16F levels below 1 MeV have been experimentally identified with well established spin-parity values and excitation energies with an accuracy of 4 - 6 keV. However, there are still considerable discrepancies in their level widths. The present work aims to explore these level widths through an independent method. The angular distributions of the 15N(7Li,6Li)16N reaction leading to the first four states in 16N were measured using a high-precision Q3D magnetic spectrograph. The neutron spectroscopic factors and the asymptotic normalization coefficients for these states in 16N were then derived based on distorted wave Born approximation analysis. The proton widths of the four low-lying resonant states in 16F were obtained according to charge symmetry of strong interaction. [ABSTRACT FROM AUTHOR]

Background: Fluorine is a key element for nucleosynthetic studies since it is extremely sensitive to the physical conditions within stars. The astrophysical site to produce fluorine is suggested to be asymptotic giant branch stars. In these stars the 15N(n,γ)16N reaction could affect the abundance of fluorine by competing with 15N(α,γ)F19. Purpose: The 15N(n,γ)16N reaction rate depends directly on the neutron spectroscopic factors of the low-lying states in 16N. Shell model calculations and two previous measurements of the (d,p) reaction yielded the spectroscopic factors with a discrepancy by a factor of ~2. The present work aims to explore these neutron spectroscopic factors through an independent transfer reaction and to determine the stellar rate of the 15N(n,γ)16N reaction. Methods: The angular distributions of the 15N(Li7,Li6)16N reaction populating the ground state and the first three excited states in 16N are measured using a Q3D magnetic spectrograph and are used to derive the spectroscopic factors of these states based on distorted wave Born approximation analysis. Results: The spectroscopic factors of these four states are extracted to be 0.96 ± 0.09, 0.69 ± 0.09, 0.84 ± 0.08, and 0.65 ± 0.08, respectively. Based on the new spectroscopic factors we derive the 15N(n,γ)16N reaction rate. Conclusions: The accuracy and precision of the spectroscopic factors are enhanced due to the first application of high-precision magnetic spectrograph for resolving the closely spaced 16N levels which cannot be achieved in most recent measurements. The present result demonstrates that two levels corresponding to neutron transfers to the 2s1/2 orbit in 16N are not good single-particle levels although 15N is a closed neutron-shell nucleus. This finding is contrary to the shell model expectation. The present work also provides an independent examination to shed some light on the existing discrepancies in the spectroscopic factors and the 15N(n,γ)16N rate. [ABSTRACT FROM AUTHOR]

The 13C(9Be,8Li)14N angular distribution was measured with a 9Be beam of 40 MeV. The proton spectroscopic factor of the 9Be ground state was extracted to be 0.73 ± 0.15 by the normalization of the calculated differential cross sections with the distorted-wave Born approximation (DWBA) to the experimental data. The spectroscopic factor was compared to existing theoretical and experimental values. [ABSTRACT FROM AUTHOR]

The evolution of massive stars with very low-metallicities depends critically on the amount of CNO nuclides which they produce. The 12N(p, γ)130 reaction is an important branching point in the rap processes, which are believed to be alternative paths to the slow 3a process for producing CNO seed nuclei and thus could change the fate of massive stars. In the present work, the angular distribution of the 2H(12N, 130)n proton transfer reaction at Ec.m. = 8.4 MeV has been measured for the first time. Based on the Johnson-Soper approach, the square of the asymptotic normalization coefficient (ANC) for the virtual decay of 13Og s. --> 12N 4- p was extracted to be 3.92 ± 1.47 fm-' from the measured angular distribution and utilized to compute the direct component in the 12N(p, γ)130 reaction. The direct astrophysical S factor at zero energy was then found to be 0.39 ±0.15 keV b. By considering the direct capture into the ground state of 130, the resonant capture via the first excited state of 130 and their interference, we determined the total astrophysical S factors and rates of the 12N(p, γ130 reaction. The new rate is two orders of magnitude slower than that from the REACLIB compilation. Our reaction network calculations with the present rate imply that 12N(p, γ)130 will only compete successfully with the ß+ decay of 12N at higher (~2 orders of magnitude) densities than initially predicted. [ABSTRACT FROM AUTHOR]

The relative γ-decay probability ratios of the neutron resonance states in 94Zr and 92Zr populated via two-neutron transfer reactions, 92Zr(18O,16O)94Zr and 90Zr(18O,16O)92Zr, have been measured to test the validity of the surrogate ratio method (SRM) in determining the (n, γ) reaction cross section. The cross sections of the 93Zr(n,γ)94Zr reaction are derived from the experimentally obtained ratios and the cross sections of the 91Zr(n,γ)92Zr reaction in the equivalent neutron energy range of En=0-8MeV. The deduced cross sections of 93Zr(n,γ)94Zr reaction agree with the directly measured ones in the low-energy region, and with the evaluated ENDF/B-VII.1 data at higher energies of En>3MeV. The agreement supports the concept of the SRM method to indirectly determine the (n,γ) reaction cross sections. [ABSTRACT FROM AUTHOR]