Elastic scattering of $^{\mathrm{3}}$He$+\alpha $ with SONIK.

Elastic scattering of $^{\mathrm{3}}$He$+\alpha $ is essential for a theoretical and phenomenological understanding of $^{\mathrm{3}}$He($\alpha $,$\gamma )^{\mathrm{7}}$Be, a key reaction in big bang nucleosynthesis and solar neutrino physics. Elastic scattering data for $^{\mathrm{3}}$He$+\alpha $ can be used in a phenomenological $R$-matrix analysis to extrapolate the $^{\mathrm{3}}$He($\alpha $,$\gamma )^{\mathrm{7}}$Be astrophysical $S$-factor ($S_{\mathrm{34}})$ to solar energies. The flux predictions for $^{\mathrm{7}}$Be and $^{\mathrm{8}}$B solar neutrinos depend critically on $S_{\mathrm{34}}$. Thus, it is important to improve the accuracy and precision of $S_{\mathrm{34}}$ at solar energies. The existing $\alpha (^{\mathrm{3}}$He,$^{\mathrm{3}}$He)$\alpha $ data do not extend to low energies and lack the precision required to constrain the extrapolation of $S_{\mathrm{34}}$ to solar energies. A new measurement of $\alpha (^{\mathrm{3}}$He,$^{\mathrm{3}}$He)$\alpha $ was performed using Scattering of Nuclei in Inverse Kinematics (SONIK) scattering chamber, a windowless, extended gas target surrounded by an array of 30 doubly-collimated silicon charged particle detectors situated at TRIUMF, ISAC-I. The measurement was performed at 9 energies with 0.873$\le E$[$^{\mathrm{3}}$He]$\le $5.462 MeV covering an angular range of 22.5$^{\mathrm{o}}\le \theta_{\mathrm{lab}}\le $135$^{\mathrm{o}}$. Experimental techniques and preliminary results from the experiment will be discussed.