Abstract
Background: The path towards the production of -process seed nuclei follows a course where the neutron rich light and medium mass nuclei play a crucial role. The neutron capture rates for these exotic nuclei could dominate over their -capture rates, thereby enhancing their abundances at or near the drip line. Sodium isotopes especially should have a strong neutron capture flow to gain abundance at the drip line. In this context, study of and reactions becomes indispensable.
Purpose: In this paper, we calculate the radiative neutron capture cross section for the reaction involving deformation effects. Subsequently, the rate for this reaction is found and compared with that of the -capture for the reaction to determine the possible path flow for the abundances of sodium isotopes.
Method: We use the entirely quantum mechanical theory of finite-range distorted-wave Born approximation upgraded to incorporate deformation effects, and calculate the Coulomb dissociation of as it undergoes elastic breakup on when directed at a beam energy of 100 MeV/u. Using the principle of detailed balance to study the reverse photodisintegration reaction, we find the radiative neutron capture cross section with variation in one-neutron binding energy and quadrupole deformation of . The rate of this reaction is then compared with that of the -capture by deduced from the Hauser-Feshbach theory.
Results: The nonresonant one-neutron radiative capture cross section for is calculated and is found to increase with increasing deformation of . An analytic scrutiny of the capture cross section with neutron separation energy as a parameter is also done at different energy ranges. The calculated reaction rate is compared with the rate of the reaction, and is found to be significantly higher below a temperature of .
Conclusion: At the equilibrium temperature of , the rate for the neutron capture had a small but non-negligible dependence on the structural parameters of . In addition, this neutron capture rate exceeded that of the -capture reaction by orders of magnitude, indicating that the -process should not break the r-process path at the isotope, thus effectively pushing the abundance of sodium isotopes towards the neutron drip line.
2 More- Received 19 February 2017
- Revised 11 April 2017
DOI:https://doi.org/10.1103/PhysRevC.95.065806
©2017 American Physical Society