(𝑒, 3𝑒) Process; coplanar geometry; ﬁve-fold differential cross-section; shake-off mechanism.
We present in this paper the results of our calculation of ﬁve-fold differential cross-section (FDCS) for (𝑒, 3𝑒) process on He atom in low momentum transfer and high electron impact energy in shake-off mechanism. The formalism has been developed in Born approximation using plane waves, Byron and Joachain as well as Le Sech and correlated BBK-type wave functions respectively for incident and scattered, bound and ejected electrons. The angular distribution of FDCS of our calculation is presented in various modes of coplanar geometry and comparison is made with the available experimental data. We observe that the present calculation is able to reproduce the trend of the experimental data. However, it differs in magnitude from the experiment. The present theory does not predict four-peak structure in summed mutual angle mode for lower excess ejected electron energies. We also discuss the importance of momentum transfer, post-collision interaction (PCI) and ion participation in the (𝑒, 3𝑒) process in constant 𝜃12 mode.