  The elastic scattering process $\Lambda p\to\Lambda p$ offers insights on
multiple problems in nuclear physics. $\mathrm{SU}(3)_F$ symmetry implies a
close agreement between the $\Lambda p$ and $pp$ scattering cross sections. The
$\Lambda p$ elastic scattering cross section can also illuminate the structure
of neutron stars. A data-mining project was started using multiple CLAS data
sets taken for other purposes with photon beams on a long liquid hydrogen
target. A $\Lambda$ produced in a process such as $\gamma p\to K^+\Lambda$ can
interact with a second proton inside the target before either decaying or
leaving the target. The good angular acceptance and momentum resolution of CLAS
make it well-suited for this type of analysis, even though it was not designed
for such a measurement. The scattered $\Lambda$ can be identified from the
$\pi^-p$ invariant mass. The four-vector of the initial $\Lambda$ is then
reconstructed in the process $Xp\to\Lambda p$, which shows a strong peak at the
$\Lambda$ mass with roughly twice the number of events as the existing world
data sample. This observation opens up the possibility of other measurements
using secondary beams of short-lived particles. This paper will discuss the
current status of the analysis, and our plans for future work on this project.

Nuclear Experiment