Injection and confinement of positron bunches in a magnetic dipole trap

We demonstrate the efficient injection of a pulsed positron beam into a magnetic dipole trap and investigate the ensuing particle dynamics in the inhomogeneous electric and magnetic fields. Bunches of similar to 10(5) e(+) were transferred from a buffer-gas trap into the field of a permanent magnet using a lossless ExB drift technique. The Delta t approximate to 0.2 . 2 mu s pulses were short compared to the toroidal rotation period, tau(d) approximate to 16 mu s, and e(+) confinement time, tau(c) approximate to 0.6 s. The redistribution dynamics were studied by measuring the delayed gamma-ray emission as the trap was emptied. This work extends the record for the number of low-energy positrons held in a dipole trap by two orders of magnitude and represents a significant advance toward the confinement of an electron-positron pair plasma.