  A new intense superthermal source for ultracold neutrons (UCN) has been
installed at a dedicated beam line at the Institut Laue-Langevin. Incident
neutrons with a wavelength of 0.89 nm are converted to UCN in a five liter
volume filled with superfluid $^4$He at a temperature of about 0.7 K. The UCN
can be extracted to room temperature experiments. We present the cryogenic
setup of the source, a characterization of the cold neutron beam, and UCN
production measurements, where a UCN density in the production volume of at
least 55 per cm$^3$ was determined.
