An improved detector for powder diffractometers

We present a new pixel design for powder diffractometers located at pulsed neutron sources. Small crystals of lithium gadolinium borate scintillator are enclosed in a tubular housing, with a single co-axial wave-length-shifting fiber used to collect and transmit the scintillator light to a pair of photomultiplier tubes. In the best case, 44 photoelectrons are detected from a neutron capture in 6Li event, when the light from both ends of the fiber is summed. Two techniques for discriminating against gamma background are described and quantified.