0000000000358807
AUTHOR
Josephine P. Briggs
Cross-sections for (e, 3e) collisions on helium: the DS6C wavefunction
A dynamically screened product of six pairwise Coulomb functions (DS6C) is used as an analytic approximation to describe the four-body Coulomb continuum state produced by electron-impact full fragmentation of helium. Good agreement is obtained with experimental data close to threshold, where four-body effects are expected to be important. Even for the high impact energy of 640 eV, four-body effects still play a role in deciding the shape of multi-differential cross-sections.
Nodes of entangledN-particle wave functions
In a recent paper [Bressanini et al. Phys. Rev. Lett. 95, 110201 (2005)] it was pointed out that ``the nodes of even simple wave functions are largely unexplored.'' Here we show that for $N$-particle wave functions nodal surfaces arise from the spin and orbital entanglement of constituent two-particle wave functions and derive, for two-electron atoms, 11 exact nodal rules applicable in $LS$ coupling. In addition, the ``higher symmetry'' identified numerically in the above paper is shown to be an approximate dynamical symmetry described by a molecular model or a classical unstable periodic orbit. We show that the analysis is readily extended to four-particle wave functions and consider the c…
The effect of dynamical screening on helium (e, 3e) differential cross-sections
A simplified derivation of dynamic screening in the case of three Coulomb-interacting particles in the continuum is given and applied to describe the shapes of multi-differential cross-sections for the (e, 3e) process on the helium atom in which the incident fast electron is treated in first-order Born approximation. A very good agreement with experimental multi-differential cross-sections is obtained for two slow ejected electrons (specifically both electrons have 5 eV) but the strategy appears to be breaking down at intermediate emission energies.