${}_{}{}^3{}_{}{}^{}\mathrm{He}({}_{}{}^3{}_{}{}^{}\mathrm{He},2p){}_{}{}^4{}_{}{}^{}\mathrm{He}$ and the termination of the proton-proton chain

Following a suggestion by Fowler, Fetisov, and Kopysov, we have extended our earlier measurements of total cross section for ${}_{}{}^3{}_{}{}^{}\mathrm{He}({}_{}{}^3{}_{}{}^{}\mathrm{He},2p){}_{}{}^4{}_{}{}^{}\mathrm{He}$ to energies as low as $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=30\mathrm{}$ KeV. The measured cross-section factors are in good agreement with the currently accepted empirical relation $S\left(E_{\mathrm{c}.\mathrm{m}.\mathrm{}}\right)=(5.2-2.8\mathrm{}{E}_{\mathrm{c}.\mathrm{m}.\mathrm{}}+1.4\mathrm{}E_{\mathrm{c}.\mathrm{m}.\mathrm{}}^{}{}_{}{}^2)$ MeVb. We have also searched the energy interval $14 \mathrm{keV} <E_{\mathrm{c}.\mathrm{m}.\mathrm{}}<28\mathrm{} \mathrm{keV}$ for a narrow resonance in ${}_{}{}^3{}_{}{}^{}\mathrm{He}({}_{}{}^3{}_{}{}^{}\mathrm{He},2p){}_{}{}^4{}_{}{}^{}\mathrm{He}$ and the results of these measurements form the subject of this paper.

[NUCLEAR REACTIONS ${}_{}{}^3{}_{}{}^{}\mathrm{He}({}_{}{}^3{}_{}{}^{}\mathrm{He},2p){}_{}{}^4{}_{}{}^{}\mathrm{He}$, $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=30-150\mathrm{}$ keV; measured $\sigma \mathrm{}\left(E\right)\mathrm{}$; also searched for a narrow resonance. Gas target.]