Determining the 6Li Doped Side of a Glass Scintillator for Ultra Cold Neutrons

Ultracold neutron (UCN) detectors using two visually very similar, to the microscopic level, pieces of optically contacted Cerium doped lithium glasses have been proposed for high rate UCN experiments. The chief difference between the two glass scintillators is that one side is 6Li depleted and the other side Li doped. This note outlines a method to determine which side of the glass stack is doped with 6Li using AmBe and 252Cf neutron sources, and a Si surface barrier detector. The method sees an excess of events around the alpha and triton energies of neutron capture on 6Li when the enriched side is facing the Si surface barrier detector.