An all-optical atom trap as a target for MOTRIMS-like collision experiments

TL;DR

This paper introduces an all-optical $^6$Li atom trap that enables momentum-resolved electron-ion coincidence experiments, overcoming previous magnetic field limitations of MOTRIMS setups and maintaining low target temperatures for high-resolution scattering studies.

Contribution

The authors develop a novel all-optical atom trap that does not require magnetic field gradients, allowing for improved coincidence detection in momentum-resolved scattering experiments.

Findings

Achieved atom temperatures of about 2 mK.

Attained number densities up to 10^9 cm^-3.

Compatible with existing MOTRIMS setups with minor modifications.

Abstract

Momentum-resolved scattering experiments with laser-cooled atomic targets have been performed since almost two decades with MOTRIMS (Magneto-Optical Trap Recoil Ion Momentum Spectroscopy) setups. Compared to experiments with gas-jet targets, MOTRIMS features significantly lower target temperatures allowing for an excellent recoil ion momentum resolution. However, the coincident and momentum-resolved detection of electrons was long rendered impossible due to incompatible magnetic field requirements. Here we report on a novel experimental approach which is based on an all-optical $^6$Li atom trap that -- in contrast to magneto-optical traps -- does not require magnetic field gradients in the trapping region. Atom temperatures of about 2 mK and number densities up to 10$^9$ cm$^{-3}$ make this trap ideally suited for momentum-resolved electron-ion coincidence experiments. The overall configuration of the new trap is very similar to conventional magneto-optical traps. It mainly requires small modifications of laser beam geometries and polarization which makes it easily implementable in other existing MOTRIMS experiments.