Asymptotic normalization coefficients from theNe20(He3

Abstract

The 20 Ne(p, γ ) 21 Na reaction rate at stellar energies is dominated by capture to the ground state through the tail of a subthreshold resonance state at an excitation energy of 2425 keV in 21 Na. Both resonant and direct capture contribute to the reaction rate while direct captures to other bound states are negligible. The overall normalization of direct capture to the subthreshold state is determined by the asymptotic normalization coefficient (ANC). Simultaneously this ANC determines the proton partial width of the subthreshold resonance state. To determine the ANC, the 20 Ne( 3 He, d) 21 Na proton transfer reaction has been measured, at an incident energy of 25.83 MeV. Angular distributions for proton transfer to the ground and first three excited states were measured, and ANCs were then extracted from comparison with distorted-wave Born approximation calculations. Using these ANCs, we calculated the astrophysical factor for 20 Ne(p, γ ) 21 Na. Our total astrophysical factor is S(0) = 5900 ± 1200 keV b. Our analysis confirms that only nonresonant and resonant captures through the subthreshold state are important.

Radiative capture of nucleons at astrophysical energies with single-particle states

“…More recently, Ref. [100] determined the ANC for 21 Na ? 20 Ne + p from the analysis of 20 Ne( 3 He,d) 21 Na proton transfer reaction at an incident energy of 25.83 MeV, and obtained the spectroscopic factor of 0.6.…”

“…The dashed and dotted lines are theoretical results from Ref [99]. and Ref [100],. respectively.Graph 18.…”

Nuclear astrophysics with radioactive beams

“…The use of heavy-ion induced, peripheral, proton-adding transfer reactions of type ( 14 N, 13 C) [402,403,307], ( 10 B, 9 Be) [404,405,402] and ( 13 C, 12 C) [406] in inverse kinematics as well as ( 3 He, d) in normal kinematics [407][408][409] has been pioneered at Texas A & M to indirectly assess the non-resonant direct-capture contribution in (p, γ ) reactions. Asymptotic normalization coefficients (ANCs) [42,407,402] are deduced from the measured angular distributions in transfer reactions at energies above the Coulomb barrier where the cross-sections are orders of magnitude higher than for direct capture processes at astrophysical energies (see Section 5.3.2).…”

Modified two-body potential approach to the peripheral direct capture astrophysical reaction and asymptotic normalization coefficients

“…[40][41][42][43][44][45][46][47][48][49][50][51] for example). However, the DWBA approach is the first order perturbation approximation over the Coulomb polarization operator V C in which the transition operator V C sandwiched by the initial and final state wave functions is assumed to be small [42].…”