Measurements of total cross sections for ${}_{}{}^3{}_{}{}^{}\mathrm{He}({}_{}{}^3{}_{}{}^{}\mathrm{He},2p){}_{}{}^4{}_{}{}^{}\mathrm{He}$ have been made for center-of-momentum energies between 80 keV and 1.1 MeV. A continuously recirculating differentially pumped gas target system was employed to minimize uncertainties in energy loss and straggling. A calorimetric device was used to integrate the beam current within the target gas. Proton angular distributions were measured at seven energies. The measured cross-section factor, $S\left(E\right)\mathrm{}$, was fitted to a linear function of energy for $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}<500\mathrm{}$ keV: $S\left(E_{\mathrm{c}.\mathrm{m}.\mathrm{}}\right)=S_0+{S_0}^{\prime }{E}_{\mathrm{c}.\mathrm{m}.\mathrm{}}$, where $S_0=\left({5.0}_{-0.4\mathrm{}}^{+0.6\mathrm{}}\right)$ MeVb and ${S_0}^{\prime }=(-1.8\mathrm{}\pm 0.5)$ b. The formula $S\left(E_{\mathrm{c}.\mathrm{m}.\mathrm{}}\right)=S_0+{S_0}^{\prime }{E}_{\mathrm{c}.\mathrm{m}.\mathrm{}}+\frac{1}{2}{S_0}^{\prime \prime }{E}_{\mathrm{c}.\mathrm{m}.\mathrm{}}^2$, with $S_0=5.2\mathrm{}$ MeVb, ${S_0}^{\prime }=-2.8\mathrm{}$ b, and ${S_0}^{\prime \prime }=2.4\mathrm{}$ b Me${\mathrm{V}}^{-1\mathrm{}}$ gives a good representation of $S\left(E\right)\mathrm{}$ over the entire range of energies studied here.

• Received 25 June 1971

DOI:https://doi.org/10.1103/PhysRevC.4.1532