Hywel Turner Evans

Swansea University: Physics

Hywel Turner Evans

Swansea University: Physics

Positrons are used in a variety of fields, including the study of materials, medical investigations and fundamental studies.

Recently, a new piece of equipment was placed on one of the positron beamlines in the Physics Department, with the possibility of increasing the number of positrons by a factor of over 100. This will push the density of the positron clouds high enough so that it is possible to study effects related to non-neutral plasmas.

The main part of the study will be to use resistive cooling when accumulating positrons.

Two main methods are used to cool positrons, - cyclotron cooling (in a strong magnetic field) and collisional cooling (on a particular gas). The first method is very expensive as a superconducting magnet is needed to create magnetic fields which are over 1 T, and the second restricts the number of positrons that can be accumulated as some are lost by annihilation with matter. The aim of the project is to investigate the efficiency of a third cooling method, - resistive cooling. In this case, the motion of the (charged) positrons is coupled to an external circuit, and the amplitude of the motion decreases as energy is dissipated in the ohmic resistance of the circuit.

Success would lead to improvements in fundamental Physics, and advancements outside the research environment.

Start date: October 2017