  The realization of electron vortex beams in the past decade has led to
numerous proposed applications in fields from electron microscopy to control
and manipulation of individual molecules. Yet despite the many unique
characteristics and promising advantages of electron vortex beams, such as
transverse momentum and quantized orbital angular momentum, there remains a
limited understanding of their fundamental interactions with matter at the
atomic scale. Collisions between electron vortex projectiles and atomic targets
can provide some insight into these interactions and we present here fully
differential cross sections for ionization of excited state atomic hydrogen
targets using electron vortex projectiles. We show that the projectile's
transverse momentum causes the ionized electron angular distributions to be
altered compared to non-vortex projectiles and that the ionized electron's
ejection angle can be controlled by adjustment of the vortex opening angle, a
feature unique to vortex projectiles. Additionally, an inherent uncertainty in
the projectile's momentum transfer leads to a broadening of the classical
binary peak, making signatures of the target electron density more readily
observable. Fully differential cross sections for aligned 2p targets exhibit
structures that can be used to determine the alignment.
