Resonance strengths in the 14N(p,γ)15Q and 15N(p,αγ)12C reactions

The 14 N(p,γ) 15 O 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 15 N(p,αγ) 12 C reaction is frequently used in inverse kinematics for hydrogen depth profiling in materials. The 14 N(p,γ) 15 O and 15 N(p,αγ) 12 C 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 14 N(p,γ) 15 O and at E p = 897 and 430 keV in 15 N(p,αγ) 12 C have been determined with improved precision, relative to the well-known resonance at E p = 278 keV in 14 N(p,γ) 15 O. The new recommended values are ωγ = 0.353 ± 0.018, 362 ± 20, and 21.9 ± 1.0 eV for their respective strengths. In addition, the branching ratios for the decay of the E p = 1058 keV resonance in 14 N(p,γ) 15 O have been redetermined. The data reported here should facilitate future studies of off-resonant capture in the 14 N(p,γ) 15 O reaction that are needed for an improved R-matrix extrapolation of the cross section. In addition, the data on the 430 keV resonance in 15 N(p,αγ) 12 C may be useful for hydrogen depth profiling.