Measurement of the Los Alamos Ultracold Neutron Source Energy Spectrum Using Gravity Crank Spectrometers*

The Los Alamos Neutron Science Center Ultracold Neutron Source is capable of generating the world's highest density of usable ultracold neutrons (UCN). We carried out the first direct measurement of the energy spectrum of UCN generated by LANSCE's upgraded Deuterium UCN source. By using two different gravity crank spectrometer geometries and extensive Monte Carlo modeling, we were able to extract an energy spectrum of the UCN delivered to the West beamline.