Reaction rates for neutron capture reactions to C, N, and O isotopes to the neutron rich side of stability

Abstract

The reaction rates of neutron capture reactions on light nuclei are important for reliably simulating nucleosynthesis in a variety of stellar scenarios.Neutron capture reaction rates on neutron-rich C-, N-, and O-isotopes are calculated in the framework of a hybrid compound and direct capture model.

Stellar neutron capture rates – key data for thesprocess

“…Fig. 6 shows that the results of the AMS measurement at 25 keV are in fair agreement with the previous experimental [51,52] and theoretical [50] data, but about two times higher than the JEFF-3.1 evaluation. For the two higher neutron energies a striking discrepancy was found with respect to the strength of the 143 keV resonance, which turned out to be a factor of 10 lower than the calculation of Herndl et al [50] (indicated by the horizontal bars in Fig.…”

“…At temperatures above T 8 = 3 the reaction rate is dominated by the 143 keV resonance, at lower temperatures by the p-wave and s-wave contributions. The calculations [50] are in reasonable agreement with two previous experiments [51,52], but exhibit a significant discrepancy compared to the most recent evaluation of JEFF-3.1, which is consistently higher than the calculation, culminating in a 25 times higher peak value for the 143 keV resonance.…”

“…The shaded areas correspond to spectrum-averaged cross sections derived from the calculated data of Ref. [50].…”

“…Accordingly, the poisoning e↵ect Figure 6. Experimental cross sections for the 13 C(n, ) 14 C reactions in the keV neutron energy region together with calculated values [50] and recent evaluations from the JEFF-3.1 data library. The width of the experimental neutron energy distributions are indicated by horizontal bars.…”

AMS Applications in Nuclear Astrophysics: New Results for 13C(n,γ) 14C and 14N(n,p) 14C

“…Previous experimental data and a comparison with calculation for 13 C(n,g) 14 C (Herndl et al 1999) indicate that the total capture cross section is dominated by a p-wave resonant contribution at energies above 20 keV. The non-resonant contribution is considerably lower and agrees well with the value extrapolated by the 1/v law from the thermal cross section (Herndl et al 1999). At temperatures above 0.3 GK the reaction rate is dominated by the 143 keV resonance, at lower temperatures p-wave and s-wave contributions are dominant.…”