Interaction of ballistic quasiparticles and vortex configurations in superfluid He3-B

TL;DR

This paper investigates how ballistic quasiparticles interact with vortex configurations in superfluid He3-B, revealing that partial screening and multiple reflections affect shadow measurements used to determine vortex line density.

Contribution

It introduces a numerical approach to account for partial screening and multiple reflections of quasiparticles in complex vortex systems, refining interpretation of shadow measurements.

Findings

Partial screening reduces the total shadow compared to simple sum of individual shadows.

Multiple reflections of quasiparticles can occur in complex vortex configurations.

Shadow measurements may not directly correspond to vortex line density due to these effects.

Abstract

The vortex line density of turbulent superfluid He3-B at very low temperature is deduced by detecting the shadow of ballistic quasiparticles which are Andreev reflected by quantized vortices. Until now the measured total shadow has been interpreted as the sum of shadows arising from interactions of a single quasiparticle with a single vortex. By integrating numerically the quasi-classical Hamiltonian equations of motion of ballistic quasiparticles in the presence of nontrivial but relatively simple vortex systems (such as vortex-vortex and vortex-antivortex pairs and small clusters of vortices) we show that partial screening can take place, and the total shadow is not necessarily the sum of the shadows. We have also found that it is possible that, upon impinging on complex vortex configurations, quasiparticles experience multiple reflections, which can be classical, Andreev, or both.