Electron and recoil ion momentum imaging with a magneto-optically trapped target

TL;DR

This paper presents a novel combination of a magneto-optical trap with a reaction microscope, enabling precise, full-angle momentum measurements of atomic fragments from laser-cooled lithium atoms, with potential applications in atomic collision studies.

Contribution

The first successful implementation of a MOTReMi apparatus, overcoming previous incompatibilities, with optimized design, nonstandard operation, and switching cycles for high-resolution momentum imaging.

Findings

Achieved momentum resolution due to low target temperature (2 mK).

Demonstrated optical preparation of lithium atoms in excited states with near 100% polarization.

Performed commissioning experiments with laser pulses and ion collisions.

Abstract

A reaction microscope (ReMi) has been combined with a magneto-optical trap (MOT) for the kinematically complete investigation of atomic break-up processes. With the novel MOTReMi apparatus, the momentum vectors of the fragments of laser-cooled and state-prepared lithium atoms are measured in coincidence and over the full solid angle. %Earlier attempts to realize this combination failed due to intrinsic incompatibilities of the magnetic fields required for MOT and ReMi. The first successful implementation of a MOTReMi could be realized due to an optimized design of the present setup, a nonstandard operation of the MOT, and by employing a switching cycle with alternating measuring and trapping periods. The very low target temperature in the MOT ($2mK$) allow for an excellent momentum resolution. Optical preparation of the target atoms in the excited Li $2^2P_{3/2}$ state was demonstrated providing an atomic polarization of close to 100\percent. While first experimental results were reported earlier, in this work we focus on the technical description of the setup and its performance in commissioning experiments involving target ionization in $266nm$ laser pulses and in collisions with projectile ions.