  The three-dimensional picture of quarks and gluons in the proton is set to be
revealed through Deeply virtual Compton scattering while a critically important
puzzle in the one-dimensional picture remains, namely, the origins of the EMC
effect. Incoherent nuclear DVCS, i.e. DVCS on a nucleon inside a nucleus, can
reveal the 3D partonic structure of the bound nucleon and shed a new light on
the EMC effect. However, the Fermi motion of the struck nucleon, off-shell
effects and final-state interactions (FSIs) complicate this parton level
interpretation. We propose here a measurement of incoherent DVCS with a tagging
of the recoiling spectator system (nucleus A-1) to systematically control
nuclear effects. Through spectator-tagged DVCS, a fully detected final state
presents a unique opportunity to systematically study these nuclear effects and
cleanly observe possible modification of the nucleon's quark distributions.
  We propose to measure the DVCS beam-spin asymmetries (BSAs) on $^4$He and
deuterium targets. The reaction $^4$He$(e,e^{\prime}\gamma\,p\,^3$H$)$ with a
fully detected final state has the rare ability to simultaneously quantify
FSIs, measure initial nucleon momentum, and provide a sensitive probe to other
nuclear effects at the parton level. The DVCS BSA on a (quasi-free) neutron
will be measured by tagging a spectator proton with a deuteron target.
Similarly, a bound neutron measurement detects a spectator $^3$He off a $^4$He
target. These two observables will allow for a self-contained measurement of
the neutron off-forward EMC Effect.
