  Results on $\Lambda$p femtoscopy are reported at the lowest energy so far. At
a beam energy of 1.76A~GeV, the reaction Ar+KCl was studied with the High
Acceptance Di-Electron Spectrometer (HADES) at SIS18/GSI. A high-statistics and
high-purity $\Lambda$ sample was collected, allowing for the investigation of
$\Lambda$ p correlations at small relative momenta. The experimental
correlation function is compared to corresponding model calculations allowing
the determination of the space-time extent of the $\Lambda$p emission source.
The $\Lambda$p source radius is found slightly smaller than the pp correlation
radius for a similar collis ion system. The present $\Lambda$p radius is
significantly smaller than that found for Au+Au/Pb+Pb collisio ns in the AGS,
SPS and RHIC energy domains, but larger than that observed for
electroproduction from He. Taking into account all available data, we find the
$\Lambda$p source radius to increase almost linearly with the number of
participants to the power of one-third.

Nuclear Experiment