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一、引言β放射性的绝对测定广泛应用于核物理、核化学、核工程和核技术应用等方面。除适用于薄膜源的4πβ-γ符合法外,要绝对测定出一个样品的β放射性,都必需知道β探测器的效率。效率中通常包含有两个因素:1.样品中发射出的β粒子在到达探测器路程中可能遇到的样品自身、样品与探测器间的空气以及探测器窗的吸收和散射。2.样品相对探测器所张的有效立体角大小。样品的β放射性自吸收和散射同样品的厚度和成分有着十分密切的关系。对薄样品,通过对自吸收等的修正,可以定出β放射性绝对强度。但
I. INTRODUCTION The absolute determination of beta radioactivity is widely used in nuclear physics, nuclear chemistry, nuclear engineering and nuclear technology applications. In addition to the 4πβ-γ law applicable to the source of the film, it is necessary to know the efficiency of the β-detector in order to determine the β-activity of a sample absolutely. There are generally two factors involved in efficiency: 1. The sample itself, the air between the sample and detector, and the detector window’s absorption and scattering of the emitted beta particles in the sample. 2. Sample relative detector effective solid angle sheet size. Beta radioactive self-absorption and scattering of samples with the same thickness and composition are closely related. For thin samples, the β-radioactive absolute intensity can be determined by correcting the self-absorption or the like. but