Out-of-plane ($e,2e$) measurements with 150eV incident beam energy on He autoionizing levels

In previous work we reported out-of-scattering-plane $(e,2e)$ measurements and calculations for helium $2\ell2\ell'$ auto\-ionizing levels at 488eV incident electron energy and scattering angle 20.5$^\circ$. The results were presented as $(e,2e)$ angular distributions energy-integrated over each level\footnote{B.A. deHarak, K. Bartschat, and N.L.S. Martin, Phys. Rev. Lett. {\bf 100}, 063201 (2008)} and the detailed energy dependence of the recoil/binary peak ratio\footnote{B. A. deHarak, K. Bartschat, and N.L.S. Martin, Phys. Rev. A {\bf 89}, 012702 (2014)}. We have now begun similar measurements at 150eV electron beam energy and scattering angle 39.2$^\circ$. The geometry is then the same as for the earlier high energy experiments: ejected electrons are detected in a plane that contains the momentum transfer direction and is perpendicular to the scattering plane. The momentum transfer is 2.1~a.u., which is the same as in the earlier experiments. We will present preliminary data and compare the angular distributions with the high energy results.