Positron emission in elastic collisions of fully ionized high-Z heavy ions

TL;DR

This paper extends theoretical models to predict observable spontaneous positron emission in elastic collisions of fully ionized heavy ions, analyzing ratios of partial probabilities and comparing cross sections for different ion collisions.

Contribution

It introduces new calculations of positron emission probabilities and ratios, suggesting potential experimental observability and comparing fully ionized with partly ionized ion collisions.

Findings

Positron emission ratios vary with minimal collision distance, indicating observability.

Cross sections for positron emission increase significantly with full ionization.

Theoretical predictions suggest experimental detection is feasible under certain conditions.

Abstract

Recent theoretical investigations of pair-production probabilities for given sets of nuclear trajectories predict the observability of spontaneous positron emission in elastic collisions of heavy ions. These calculations are extended to the investigation of ratios $P_{y}(\eta)/P_{y}(1)$ for partial probabilities of positron emission at small positron energies. The results suggest a possible observability of spontaneous positron emission in elastic collisions of bare heavy ions by analyzing the slope of $P_{y}(\eta)/P_{y}(1)$ for values of $R_{min}$ $~_{\sim}\!\!\!\!^<$ 0.75 $R_{cr}$. In addition calculations of cross sections for positron emission in U+Cm and Cm+Cm collisions of fully ionized heavy ions are compared with former results with partly ionized projectiles and show an increase by factors of 57 to 72.