Portable gamma camera with a rotated coded mask for the remote measurement of radioactivity at nuclear installation

New gamma imager - portable gamma camera with a rotated mask for the remote measurement of radioactivity in the reactor areas was developed. The constructions and main parameters of this instrument are described. The imaging with instrument is based on combined position sensitive detector: scintillating plate + fiber optic taper + image intensifier with 2 MCP + digital video camera with industrial CCD. Scintillating plate has useful diameter 38 mm and thickness 3 mm. As the aperture for gamma imaging is used rotated coded mask (hURA) of 9 ranks. Interesting feature of masks of type hURA consists that the mask turns to the contrast - an antimask at turn on 60°. Mask turn on 600 is carried out by the electromotor, established on the device case. Procedure a mask-antimask allows: 1) to lower influence of background radiation on the detector, 2) to eliminate influence imperfect of the mask having a finite thickness. The dimensions of detecting head are: length ~50 cm and diameter ~12 cm. A special portable computer with software package is used for control all gamma imager sub-systems by operator, for processing of gamma images, storage and displaying and for operation with images. The distance between detecting head and computer may be up to 50 meters.