^134/137Cs isotopes discrimination via a β/γ time-coincidence energy gating digital autoradiographic system

Since the discovery of radioactivity, autoradiography has been extensively used in nuclear physics to characterize the distribution of radionuclides into biological or inert samples. In this study, we present an original add-on method to the real-time digital autoradiography, aiming at identifying ¹³⁴Cs from ¹³⁷Cs events in radioactive maps measured from sample surface on the basis of a micro-pattern gaseous detector coupled to a crystal-based photon scintillation detector. Using the fast timing of both instruments, we successfully demonstrated the possibility of discriminating both isotopes and quantifying their isotopic ratios. In particular, we achieved a rejection rate of ¹³⁷Cs events close to 100 % while maintaining high-resolution mapping of ¹³⁴Cs distributions. Tests mixed samples showed strong linear correlations between detected event ratios and known isotope activities. This emerging method offers a promising tool for radiocesium source attribution and further opens new perspectives in digital autoradiography for multi-isotope mapping in complex materials.