Small Business	Research Institution
Photon Imaging, Inc. 19355 Business Center Drive Suite #8 Northridge, CA 91324-3503 Dr. Bradley E. Patt, Principal Investigator Dr. Bradley E. Patt, Business Official (818) 709-2468	Lawrence Berkeley National Laboratory 1 Cyclotron Road Berkeley, CA 94720

With the extensive inventories of nuclear grade weapons materials in the former Soviet Union and in the United States, there is a growing concern about the illegal movement of these materials. Therefore, reliable low cost screening for these materials at ports of exit from the former Soviet Union and at ports of entry to the United States is of increasing interest. At the present time, there are no low cost reliable sensing units for the detection of these materials. This project will develop cost effective technology to detect and identify gamma-ray emission from weapons-grade materials. The approach takes advantage of the recent development of a new type of photodetector, the silicon drift photodetector (SDP), which will be coupled to a Thallium-activated Cesium Iodide(CsI[Tl]) scintillator. Phase I will enable the fabrication of components for the sensing head of a gamma-ray detector. Specifically, CsI(Tl) will be deposited onto the SDP and the resulting system will be evaluated. Modifications to existing readout electronics will be developed, tested, and evaluated to determine the feasibility of constructing a prototype gamma-ray spectrometer in Phase II.

Commercial Applications and Other Benefits as described by the awardee: A sensing head with an appropriate analyzing code should lead to the unambiguous identification of gamma rays from nuclear grade weapons materials and to the installation of instruments based on this technology at ports of exit from the former Soviet Union and ports of entry to the United States.