Low-Energy nuclear reactions with hydrogen isotopes

Abstract

Using the Los Alamos Low-Energy Fusion Cross-Section Facility (LEFCS), we have completed the study of the D(t, α)n reaction from E t = 12.5–117 keV, and now have measured angular distributions of the reactions D(d, p)T and D(d, 3He)n from E d= 20–117 keV. The experimental equipment features a windowless cryogenic target, a precision beam-intensity calorimeter, a 10 to 120 keV accelerator producing negative tritium ions, an accurate target gas-flow and temperature system, and a tritium gas-handling system. Most of the quite anisotropic angular distributions of the D+D reactions have relative errors of about 1% and the integrated cross-sections have absolute errors of about 1.5%. Astrophysical S functions extracted from the data and also from a least-squares fit of a+ b cos 2 θ to the data show a curious behavior with energy. The cross-sections, which agree with previous but less accurate data, are compared with R-matrix calculations. We also show preliminary results for alpha-particle spectra of the T(t, α)nn reaction. A feature of this experiment is the flow through our windowless target of 1.5 standard liters of tritium gas per day.