  We present results from the first experimental study of strongly
radiatively-cooled magnetic reconnection. Two exploding aluminum wire arrays,
driven simultaneously by the Z machine ($I_{max} = 20 \, \text{MA}$,
$t_{\text{rise}} = 300 \, \text{ns}$), generate a radiatively-cooled
reconnection layer ($S_L \approx 120$) in which the total cooling rate exceeds
the hydrodynamic transit rate ($\tau_{\text{hydro}}/\tau_{\text{cool}} > 100$).
Measurements of X-ray emission from the reconnection layer using a filtered
diode ($>1$ keV) show a narrow (50 ns FWHM) burst of emission at 220 ns after
current start, consistent with the formation and subsequent rapid cooling of
the reconnection layer. Time-gated X-ray images of the reconnection layer show
fast-moving (up to 50 km/s) hotspots inside the layer, consistent with the
presence of plasmoids observed in 3D resistive magnetohydrodynamic simulations.
X-ray spectroscopy shows that these hotspots generate the majority of Al
K-shell emission (at around 1.6 keV) prior to the onset of cooling, and exhibit
temperatures of 170 eV, much greater than the temperature of the plasma inflows
and the rest of the reconnection layer.
