A Noise Spectroscopy Detector Array for Non-Intrusive Cargo Inspection

Noise Spectroscopy is a statistical technique to extract spectral information from x rays transmitted through cargo and is especially effective when used with fast scintillation detectors and waveform digitization electronics to measure both the waveform mean and its fluctuations during each x-ray pulse. Previous work established feasibility in experiments using LYSO crystals using high-speed electronics in a laboratory setting. Here we describe the results of experiments performed on a larger prototype of 80 LYSO detectors, covering a length of about 1 meter, inserted into a radiography test facility. Calibration data was obtained, and various cargoes with hidden objects were imaged using the system. The analysis of this data provides proof that a practical implementation of Noise Spectroscopy in a cargo inspection system is feasible and also effective in detecting small high-Z objects in realistic cargoes.