Long-distance detection of alpha-radioactivity: Method and device.

Negatively charged ions from the alpha particle tracks are detected by the discharge wire counter opened to the air. Ion clusters are transferred from the particle tracks to the detector volume by an air flux. It allows a remote detection of very low concentrations of alpha particles. In contrast to the existing long-range alpha particle detection technique this method employs a detector working in a counting mode using a gas discharge method with an open-air proportional counter that provides sharp selectivity and accuracy of measurements. The device allows to detect alpha contamination over large surface areas, including places hard to reach, using different nozzles such as the tube nozzle or disc nozzle. The basic parameters of the device are: detection distance--0.5 m; time of detection--10 s; the sensitivity per unit area--0.05 Bq/cm(2). Also the auto-calibration technique and results are presented. That allows using the device under different ambient conditions by making an automatic recalibration.