Profiling Charged Particle Beams Using Atomic Magnetometry

We present the results of 2D profiling of a charged particle beam using coherent atomic magnetometry. Sending a beam of electrons through a low-pressure Rb vapor induces a Zeeman shift in the degenerate ground states of the alkali atoms. A probe laser resonant with the the D₂ transition of ⁸⁵Rb reacts with a rotation in its polarization angle directly proportional to the electron beam's magnetic field. The spatial dependence of the magnetic field can then be captured by imaging the probe laser polarization components. The obtained magnetic field distribution allows us to reconstruct the current density of the particle beam and obtain fundamental beam quantities such as position, width, and total current. We also verify the accuracy of such quantities against several secondary detection schemes such as optical transition radiation. This approach to particle beam profiling is aimed as a non-invasive solution to a wide bandwidth of charged particle beam energies and current densities, and can be extended to obtain 3D profiles.