Fully differential cross sections for singly ionizing 1-MeV $p$+He collisions at small momentum transfer: Beyond the first Born approximation

We present calculations of the electron angular distributions in the single ionization of helium by 1-MeV proton impact at momentum transfer of 0.75 a.u. and ejected-electron energy of 6.5 eV. The results using the first and second Born approximations and the 3C model with different trial helium functions are compared to the experimental data. A good agreement between theory and experiment is found in the case of the 3C final state and a strongly correlated helium wave function. The electron-electron correlations in the He atom are found to influence the ratio of the binary and recoil peak intensities.

Figure 1

FDCS in coplanar geometry using the PWFBA (black dashed line) and PWSBA (red solid line) with the Hy ground state of the He atom (15). Experimental value from [16] are represented by points, $\overline{E}=0.9$.

Figure 2

FDCS in coplanar geometry using the PWFBA (black dashed line) and 3C model (red solid line) with the RHF ground state of the He atom. Experimental value from [16] are represented by points, $\lambda ={10}^{-3}$.

Figure 3

The same as in Fig. 2, but in the case of the SPM ground state of the He atom.

Figure 4

The same as in Fig. 2, but in the case of the CF ground state of the He atom.

Figure 5

FDCS in the case of the CF ground state of the He atom within PWFBA (red dashed line), 3C model (black solid line), and the 3C model with $1/v_p=0$ (blue dash-dotted line) and $1/|{\vec{v}}_p-{\vec{k}}_e|=0$ (bronze yellow dotted line). $\lambda ={10}^{-3}$.