一、测量原理~(90)Sr-~(90)Y的衰变纲图比较简单。但它是一个纯β发射体,所以对它的放射性强度的绝对测量用一般的4πβ-γ符合法就比较困难。本工作采用4πβ-γ符合效率示踪法测~(90)Sr-~(90)Y的放射性强度。测量方法的基本原理是把待测的~(90)Sr-~(90)纯β发射体与放射性强 First, the measuring principle ~ (90) Sr- ~ (90) Y of the declination outline is relatively simple. However, it is a pure beta emitter, so the absolute measure of its radioactivity is more difficult than the normal 4πβ-gamma method. In this work, the radioactivity of ~ (90) Sr- ~ (90) Y was measured by 4πβ-γ in accordance with the efficiency tracing method. The basic principle of the measurement method is to test the ~ (90) Sr- ~ (90) pure beta emitters and radioactive strong