Determination of 240Pu and 239Pu Ratio by Spontaneous Fission Counting

The ²⁴⁰Pu content in Pu samples was determined by spontaneous fission measurement with a p-n junction silicon detector. Prolonged continuous measurements were run, extending over several hundred hours, using a transistorized counting system to obtain the required stability during such long periods. The results indicated that this method is applicable to the determination of ²⁴⁰Pu/²²³⁹Pu ratio.