FIELD: test of environmental radioactivity, detection of fast change of concentration of radon in air. SUBSTANCE: air purified from daughter products of radon disintegration is blown through cylindrical gaseous-discharge detector at such rate that time of flight of any atom through volume of detector is markedly less than average life time of atom formed with disintegration of atom of radon in volume of detector. EFFECT: diminished potential of registration of alpha particles emitted by daughter products of radon disintegration.
