Three-dimensional calculations of positron creation in supercritical collisions of heavy nuclei

TL;DR

This paper presents advanced three-dimensional calculations of positron creation probabilities in supercritical heavy nuclei collisions, incorporating rotational coupling effects and solving the time-dependent Dirac equation with a pseudospectral method.

Contribution

It introduces a comprehensive 3D approach beyond the monopole approximation, including rotational coupling, to accurately model positron creation in heavy nuclei collisions.

Findings

Positron distributions are highly isotropic.

Rotational coupling has minimal impact at 6-8 MeV/u collision energies.

Total positron creation probabilities are calculated with improved accuracy.

Abstract

Energy--angle differential and total probabilities of positron creation in slow supercritical collisions of two identical heavy nuclei are calculated beyond the monopole approximation. The time-dependent Dirac equation (TDDE) for positrons is solved using the generalized pseudospectral method in modified prolate spheroidal coordinates, which are well-suited for description of close collisions in two-center quantum systems. In the frame of reference where the quasimolecular axis is fixed, the rotational coupling term is added to the Hamiltonian. Unlike our previous calculations, we do not discard this term and retain it when solving the TDDE. Both three-dimensional angle-resolved and angle-integrated energy distributions of outgoing positrons are obtained. Three-dimensional angle-resolved distributions exhibit a high degree of isotropy. For the collision energies in the interval 6 to 8 MeV/u, the influence of the rotational coupling on the distributions and total positron creation probabilities is quite small.