Effects of the Leakage Magnetic Field from an Analog Meter on the Response of Scintillation Survey Meters

Abstract

Effects of the weak leakage magnetic field are studied on the response of two kinds of scintillation survey meters: an ordinary type for γ-rays and that optimized for the detection of low-energy photons from ¹²⁵I.In the presence of the magnetic field, the response of the optimized survey meter decreases to the photons from ¹²⁵I, and increases considerably to the background radiations. On the other hand, the response of the ordinary survey meter decreases slightly to both the γ-rays from ¹³¹I and the background radiations.From analysis of the pulse-height spectra for the radiations, such variations of the response are ascribed to the reduction of the amplification factor of photomultiplier tubes by the magnetic field.