Atomic and Molecular Physics Using Positron Traps and Trap-Based Beams

Clifford M. Surko, R. G. Greaves, Koji Iwata +1 more

E.A. Gianturco

Clifford M. Surko

Jonathan Peter Merrison

The low intensity and poor resolution of conventional slow positron beams is limiting the study of atomic and molecular collisions and prohibits more ambitious fundamental studies. The application of trapping promises huge enhancement in instantaneous beam intensity; ideal for studying short lived positron bound states. Cooling of trapped positrons gives vast improvement in energy and spatial resolution and gives access to a new low energy regime. This new technology is proving to be both challenging and exciting; the relative merits of several different trapping schemes will be discussed and recent progress presented.

James Patrick Sullivan, S. J. Gilbert, Joan P. Marler +3 more

The development of buffer-gas trapping and magnetized beam formation has provided positron beams with significantly improved energy resolution $(\ensuremath{\Delta}E<~0.025\mathrm{eV})$ compared to those available previously. Analysis techniques have been developed to take advantage of the fact that the beam is in a magnetic field of $\ensuremath{\sim}0.1\mathrm{T}.$ This has enabled scattering experiments at lower energies and with significantly improved state selectivity for excitation experiments than had been possible previously. A detailed description of these techniques is presented. Data are presented for a variety of cross sections for scattering of positrons from atomic and molecular targets.

Tosi, Paolo, Bassi, Davide