A Gas Electron Multiplier (GEM) Detector for Fast Neutron Imaging

We have built a Gas Electron Multiplier (GEM) detector for detection of fast neutrons at Lawrence Berkeley National Laboratory. The detector consists of a 0.0625 inch thick polypropylene neutron converter, three GEM foils and a grid of 16 readout pads on a printed circuit board. In this talk, we present images of the GEM detector, the results of tests with $^{60}$Co, AmBe sources and our neutron beam, and a comparison between the proposed fast neutron GEM detector and a fast neutron $^{238}$U fission chamber we purchased. One of the advantages of the GEM detector over the fission chamber is the fact that it provides the x-y position information of the neutrons.