Injection and trapping in a prototype dipole trap
To address key questions that needed to be answered early in the experiment planning process, we have conducted a number of proof-of-principle tests in a trap based on a supported permanent magnet. These have demonstrated that positrons can be losslessly transported from "open" magnetic field lines (connecting back to the NEPOMUC beam line) onto "closed" dipole field lines using ExB drifts. These drifts are created by strategically tailoring the 3D electrostatic potential landscape by biasing electrodes just outside the edge of the confinement region. By switching off those potentials, positrons that were transiting through the confinement region on the closed field lines in the trap become trapped there. We have also found that the drift injection technique works for a range of relevant energy distributions, and it is not impeded by the trap being pre-filled with an electron space charge.