Portable gamma- and X-ray analyzers based on CdTe p-i-n detectors

Several portable instruments are designed using previously reported CdTe de tector technology. These can be divided into three groups according to thei r energy ranges: (1) 3-30 keV XRF analyzers, (2) 5-120 keV wide range XRF a nalyzers and (3) gamma-ray spectrometers for operation up to 1500 keV. Thes e instruments are used to inspect several hundreds of samples in situ durin g a working day in applications such as a metal alloy verification at custo ms control. Heavy metals are identified through a 3-100 mm thick package wi th these instruments. Surface contamination by heavy metals (for example to xins such as Hg, Th and Pb in housing environmental control), the determina tion of Pb concentration in gasoline, geophysical control in mining, or nuc lear material control are other applications. The weight of these XRF probe s is about 1 kg and two electronic designs are used: one with embedded comp uter and another based on a standard portable PC. The instruments have good precision and high productivity for measurements in situ. The detection li mit of Ce is about 0.03% when measured in the presence of 10% barium for 15 s. The detection limit when measuring K-shell X-ray of heavy metals contam ination is about 0.1 mg/cm(2) for 15 s. Two types of probes for gamma-spect rometry with small and large ( > 30 mm(3)) detector volumes provide both hi gh- and low-activity of nuclear fuel analysis. The maximum distance between the probes and electronics unit is 20 m. The gamma-spectrometers are equip ped with electronics to correct signal distortion due to slow carrier effec ts. This allows the instrument to achieve an energy resolution of about 2.5 keV at 662 keV. Several modes to process spectra are possible including se miquantitative and total real-shape fitting. (C) 1999 Elsevier Science B.V. All rights reserved.