A compilation of charged-particle induced thermonuclear reaction rates

Energy levels of light nuclei A=8,9,10

NACRE II: an update of the NACRE compilation of charged-particle-induced thermonuclear reaction rates for nuclei with mass number A < 16

A new astrophysical reaction rate of 12C(α, γ)16O has been calculated based on our recent determination of the E1- and E2-capture cross sections. The R-matrix method has been applied to describe the SE1- and SE2-factor functions as well as the data of elastic α scattering and the β-delayed α decay of 16N from other experiments. The resulting reaction rate for stellar temperatures of T9 = 0.04-10 is presented in both tabular form and an analytic expression. A new temperature dependence of the reaction rate was obtained when compared with reported evaluations. The associated uncertainties were reduced considerably in comparison to previous determinations.

http://iopscience.iop.org/article/10.1086/338384/pdf

Astrophysical Reaction Rate of 12C(α, γ)16O

Supplement to energy levels of a = 21-44 nuclei. (vii)

Excitation functions and angular distributions of the 9Be(p, α)6Li and 9Be(p, d)8Be reactions have been measured over the energy range E p = 16 to 390 keV. The data are dominated by one broad resonance including interference effects with a direct process. The effects of electron screening have also been observed, which are however significantly larger than expected. The deduced reaction rates at T9 ≤ 1 are in excellent agreement with values given in a compilation.

Low-energy S(E) factor of 9 Be( p, α ) 6 Li and 9 Be( p, d ) 8 Be

Nuclear resonant reaction analysis techniques for hydrogen depth profiling in solid materials typically have used15N ion beams at 6.40 MeV and19F ion beams at 6.42 MeV, which require a tandem accelerator. We report a new technique using an18O ion beam at a resonance energy of 2.70 MeV, which requires only a single stage accelerator. Improved values of the nuclear parameters for the 2.70 MeV (18O) and 6.40 MeV (15N) resonances are reported. The beam energy spread was investigated for different ions and ion charge states and found to scale with the charge state. Data obtained using atomic and molecular gas targets reveal the research potential of Doppler spectroscopy. Examples of hydrogen depth profiling in solid materials using15N and18O ion beams are presented.

Hydrogen depth profiling using 18 O ions

Excitation functions and forward-backward anisotropies have been measured for the7Li(p, γ)8Be capture reaction over the proton energy rangeE

 p
 =100 to 1500 keV, using a 4π summing crystal and Ge(Li) detectors, respectively. The data show at all energies the presence of El and M1 capture amplitudes arising from the direct capture (DC) process and theE

 R
 =441 and 1030 keV resonances, respectively. Due to the observed DC process, the present data increase significantly the reaction rates (up to a factor of 110) compared to values given in the compilation. The data and their analyses remove the recent criticism on DC model calculations, which had implied a significant reduction in the extrapolated S(E) factor for7Be(p,γ)B and thus in the predicted flux of high-energy solar neutrinos; thus, the solar neutrino problem is still with us.

S. Schmidt

Papers

Low-energy S(E) factor of 9 Be( p, α ) 6 Li and 9 Be( p, d ) 8 Be

Hydrogen depth profiling using 18 O ions

The S(E) factor of 7 Li(p, γ) 8 Be and consequences for S(E) extrapolation in 7 Be(p, γ 0 ) 8 B

22Na(p,γ)23Mg resonant reaction at low energies

22Na(3He,d)23Mg reaction studies of states near the proton threshold and hydrogen burning of 22Na