New Determination of the ¹⁴C(n, <i>γ</i>)¹⁵C Reaction Rate and Its Astrophysical Implications

Abstract We present a novel experiment to investigate the spectroscopic factor (SF) of the 15 C ground state for the first time using single-neutron removal transfer reactions on 15 C. Two consistent SFs were derived from the (p, d) and (d, t) reactions, which were subsequently used to deduce the 14 C(n, γ ) 15 C reaction cross section and the corresponding stellar reaction rate. A typical cross section of 3.89 ± 0.76 μ b is determined at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>E</mml:mi> </mml:mrow> <mml:mrow> <mml:msub> <mml:mrow/> <mml:mrow> <mml:mi mathvariant="normal">c</mml:mi> <mml:mo>.</mml:mo> <mml:mi mathvariant="normal">m</mml:mi> <mml:mo>.</mml:mo> </mml:mrow> </mml:msub> </mml:mrow> </mml:msub> </mml:math> = 23.3 keV. At the temperature range of 0.01–4 GK, our new reaction rate is 2.4–3.7 times higher than that of the first direct measurement and 20%–25% lower than that of the most recent direct measurement. Moreover, it is interesting that we can associate a long-standing nuclear structure issue, i.e., the so-called “quenching” effect, with this astrophysically relevant reaction. Finally, motivated by astrophysical interests of this reaction decades ago, implications of our new rate for several astrophysical problems are evaluated using state-of-the-art theoretical models. Our calculations demonstrate that the abundances of 14 N and 15 N can be enhanced in the inner regions of asymptotic giant branch stars, though with minimal impact on the chemical compositions of the interstellar medium. In the inhomogeneous Big Bang nucleosynthesis, the updated reaction rate can lead to a ∼20% variation in the final yields of 15 N in neutron-rich regions. For the r -process in the core-collapse supernovae, a slight difference of ∼0.2% in the final abundances of heavy elements with A &gt; 90 can be found by using our new rate.