Resonance strengths in the 14N(p, \gamma)15O and 15N(p, \alpha \gamma)12C reactions

TL;DR

This study precisely measured resonance strengths in key nitrogen reactions relevant to stellar hydrogen burning and material analysis, providing improved data for astrophysics and material science applications.

Contribution

The paper presents new, more accurate resonance strength measurements for specific nitrogen reactions, enhancing previous data and supporting future research in astrophysics and material analysis.

Findings

Resonance strengths at 1058 keV, 897 keV, and 430 keV determined with improved precision.

Redetermination of decay branching ratios for the 1058 keV resonance.

Data supports better R-matrix extrapolation and hydrogen depth profiling techniques.

Abstract

The 14N(p, \gamma)15O reaction is the slowest reaction of the carbon-nitrogen-oxygen cycle of hydrogen burning in stars. As a consequence, it determines the rate of the cycle. The 15N(p, \alpha \gamma)12C reaction is frequently used in inverse kinematics for hydrogen depth profiling in materials. The 14N(p, \gamma)15O and 15N(p, \alpha \gamma)12C reactions have been studied simultaneously, using titanium nitride targets of natural isotopic composition and a proton beam. The strengths of the resonances at Ep = 1058 keV in 14N(p, \gamma)15O and at Ep = 897 and 430 keV in 15N(p, \alpha \gamma)12C have been determined with improved precision, relative to the well-known resonance at Ep = 278 keV in 14N(p, \gamma)15O. The new recommended values are \omega \gamma = 0.353$\pm$0.018, 362$\pm$20, and 21.9$\pm$1.0 eV for their respective strengths. In addition, the branching ratios for the decay of the Ep = 1058 keV resonance in 14N(p, \gamma)15O have been redetermined. The data reported here should facilitate future studies of off-resonant capture in the 14N(p, \gamma)15O reaction that are needed for an improved R-matrix extrapolation of the cross section. In addition, the data on the 430 keV resonance in 15N(p, \alpha \gamma)12C may be useful for hydrogen depth profiling.