Method and assembly for characterizing a solid sample likely to contain a radioactive element disintegrating according to a disintegration chain by emission of a and/or b particles

A characterization method for characterizing whether a solid sample contains a radioactive element decaying through a decay chain by the emission of α and/or β particles, the decay chain passing successively through a first radioactive isotope and then a second radioactive isotope, the first isotope decaying by the emission of a first particle of type α or type β with a first half-life period, the second isotope decaying by emission of a second particle of type α or type β with a second half-life period shorter than the first half-life period, the method comprising the following steps:

• performing autoradiography of the solid sample with detection using a detector of the α and/or β particles emitted by the solid sample and, for each detected α or β particle, recording the following data:
• a detection time of the particle,
• spatial coordinates of an emergence point of the particle, and
• a charge deposited by the particle upon detection;
• and
• analyzing the recorded data to detect a presence of the first radioactive isotope and/or second radioactive isotope in the solid sample, the analyzing of the recorded data comprising the following sub-steps:
• identifying pairs comprising a first detected particle and a second detected particle later than the first, said pair meeting the following criteria:
• respective detection times of the first detected particle and the second detected particle separated by a time interval that is less than a given pair's time limit;
• a distance between the respective emergence points of the first detected particle and the second detected particle less than a given pair spatial limit;
• a charge deposited by the first detected particle corresponding to the type of the first particle emitted by the first isotope during its decay;
• and
• a charge deposited by the second detected particle corresponding to the type of second particle emitted by the second isotope during its decay;
• and
• counting a number of the identified pairs.

A characterization set of a solid sample likely to contain a radioactive element decaying through a decay chain by an emission of α and/or β particles, the decay chain passing successively through a first radioactive isotope and then a second radioactive isotope, the first isotope decaying by the emission of a first particle of type α or type β with a first half-life period, the second isotope decaying by the emission of a second particle of type α or type β with a second half-life period shorter than the first half-life period, the characterization set comprising:

• an autoradiography system of the solid sample comprising a detector configured to detect the α and/or β particles emitted by the solid sample, and, for each detected α or β particle, record the following data:
• detection time of the particle,
• spatial coordinates of an emergence point of the particle, and
• charge deposited by the particle upon detection;
• a unit for analyzing the recorded data, being configured to identify a presence of the first radioactive isotope and/or second radioactive isotope in the solid sample, the data analysis unit being configured to:
• identify the pairs that comprise a first detected particle and a second detected particle detected later than the first, said pair meeting the following criteria:
• respective detection times of the first detected particle and the second detected particle separated by a time interval that is less than a given pair's time limit;
• a distance between the respective emergence points of the first detected particle and the second detected particle less than a given pair spatial limit;
• a charge deposited by the first detected particle corresponding to the type of the first particle emitted by the first isotope during its decay;
• and
• a charge deposited by the second detected particle corresponding to the type of second particle emitted by the second isotope during its decay;
• counting a number of the identified pairs.