  We propose a physics program at JLab with CLAS12 focusing on open-charm
measurements, aiming to complement and expand current studies of $J/\psi$ at
(sub) threshold. This program will aid us in elucidating the $J/\psi$
production mechanisms, which is crucial for interpreting data in terms of gluon
form factors and offer potential insights into the intrinsic charm hypothesis
and cold-nuclear matter effects. We discuss the technical feasibility of
integrating the sPHENIX monolithic-active-pixel sensor (MAPS) tracker, known as
MVTX, with the CLAS12 detector. The sPHENIX MTVX would support an open-charm
program by providing excellent secondary-vertex performance for tagging $D$
mesons. We study the kinematics of $\gamma p \to \bar{D}^{0}\Lambda_{c}$
through phase-space simulations and estimate rates for the tagged
quasi-photoproduction regime available with the CLAS12 forward tagger. While
open-charm cross-sections at threshold remain uncertain, various predictions
suggest that these measurements could be feasible when combined with
conservative estimates of detector acceptance and luminosity. These preliminary
estimates motivate detailed Geant detector simulations of signals and
backgrounds, along with thorough technical assessments of operating conditions,
to further explore the feasibility of these measurements in future dedicated
CLAS12 experiments at JLab.
