DEVELOPMENT OF AIRBORNE SURVEILLANCE INSTRUMENTATION.
EDGERTON GERMESHAUSEN AND GRIER INC SANTA BARBARA CALIF
Pagination or Media Count:
A gamma ray detector was constructed using an inorganic scintillator, CsIT1, that is viewed by three photomultiplier PM tubes. The phosphor is encased in a plastic fluor so that the PM tube array also detects scintillations in the fluor. The detector forms a phoswich assembly Rev. Sci. Inst. 23414-417 1952, permitting pulse shape discrimination against charged particle reactions occurring within it. External circuitry rejects single signals from the fluor, and fluorphosphor coincident signals. The unit approaches 100 rejection effectiveness in preventing charged-particle reactions in the detector from introducing signals into the measurement circuitry. Gamma ray losses resulting from gamma-fluor reactions are less than 9 of the total recorded gamma activity in the main CsIT1 detector for energies below 1.4 Mev. The detector incorporates a small inset-well crystal lying on the central axis, that is optically separated from the CsI the ratio of inset-well count rate to main crystal count rate provides a directionality parameter defining source position with respect to crystal axis. The detector shows an energy response linearity within the limitations of the analyzer used in the measurements, or - 12. The resolution for Cs-137 gamma rays exhibited by the assembly is 15.4. Gamma ray spectral data can be collected with the charged particle rejection feature in operation. Author
- Nuclear Instrumentation