Search

The angular distributions of 12C + 90,92,94,96Zr elastic scattering were measured with the Q3D magnetic spectrometer at the HI-13 tandem accelerator, Beijing. The real part of optical potential were extracted by analysing these angular distributions. The analysis enable us to avoid the influence of Coulomb effect and to observe the dependence of optical potential on the nuclear properties. With the deduced potential parameters, the experimental elastic scattering angular distributions can be reproduced very well. Formulas to infer global heavy-ion potential parameters were obtained then by analyzing the extracted optical potential parameters. The formulas can be used widely in heavy-ion nuclear reactions.

Copyright of SHILAP Revista de Lepidopterologia is the property of Sociedad Hispano-Luso-Americana de Lepidopterologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

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 12C(α,γ)16O reaction plays a key role in the evolution of stars with masses of M>0.55M⊙. The cross-section of the 12C(α,γ)16O reaction within the Gamow window (Ec.m.=300keV, T9=0.2) is extremely small (about 10-17 barn), which makes the direct measurement in a ground-based laboratory with existing techniques unfeasible. Up until now, the cross-sections at lower energies can only be extrapolated from the data at higher energies. However, two subthreshold resonances, located at Ex=7.117MeV and Ex=6.917MeV, make this extrapolation more complicated. In this work, the 6.917 MeV subthreshold resonance in the 12C(α,γ)16O reaction was investigated via the 12C(11B,7Li)16O reaction. The experiment was performed using the Q3D magnetic spectrograph at the HI-13 tandem accelerator. We measured the angular distribution of the 12C(11B,7Li)16O transfer reaction leading to the 6.917 MeV state. Based on the finite-range distorted wave Born approximation (FRDWBA) and coupled-reaction-channel (CRC) analysis, we derived the asymptotic normalization coefficient (ANC) of the 6.917 MeV level in 16O to be (1.10±0.29) ×1010fm-1, with which the reduced α width was computed to be 18.0±4.7keV at the channel radius of 6.5 fm. Finally, we calculated the astrophysical SE2(300) factor of the ground-state transitions to be 46.2 ± 7.7 keV b. The result for the astrophysical SE2(300) factor confirms the values obtained in various direct and indirect measurements and presents an independent examination of the most important data in nuclear astrophysics. [ABSTRACT FROM AUTHOR]