Method and apparatus for measuring density

摘要

A distance between a radiation source and a detector is first set to a first distance and the number of pulses of a gamma -ray is detected. Then, the distance between the radiation source and the detector is set to a second distance different from the first distance and the number of gamma -ray pulses is detected. A density rho of a sample is finally calculated on the basis of a ratio of the two detection pulse numbers which were detected. The radiation source is set on the surface of the sample or in the sample. The sample detector is set on the sample surface. Fundamentally, one radiation source and two detectors are used. In the case of using one radiation source and one detector, either one of them is moved and the number of pulses is detected twice.