Laser-induced photo transmutation of 126Sn – A hazardous nuclear waste product-into short-lived nuclear medicine of 125Sn

Relativistic electrons, generated in the interaction of an ultra-intense laser pulse with plasma in front of a high-Z   solid target, when passing near the nuclei of the solid target produce several MeV highly collimated Bremsstrahlung gamma beam, which can be used to induce photo-nuclear reactions. In this work the possibility of photo-induced transmutation (γn) of a nuclear waste of 126Sn126Sn with a half-life of 100,000 years into 125Sn125Sn with a half-life of 9.64 days was investigated for the first time. Calculations based on the available experimental data show that the Bremsstrahlung γ beam generated by irradiating a 2 mm thick tantalum target as a converter with 1020Wcm-2μm2 and 10 Hz table-top laser for an hour can produce 293 Bq activity in a 1 cm thick 126Sn126Sn sample placed directly behind it. The remarkable feature of this work is to evaluate the optimal laser intensity to produce maximum activity of 2257 Bq which is 1.18×1021Wcm-2μm2. The selective excitation of nuclear resonance states are discussed by studying the rate equations and calculating the Einstein coefficient. According to our calculations, we achieve relative decay rate of 0.0025, for two possible decay channels. Our results show the most probable channel for this mechanism which has a good agreement with direct excitation process.

► This is an analytical transmutation of toxic nuclear waste of tin into the radio medical product by ultra-intense lasers.
► The maximum probability of the transmutation by two different channels is introduced.
► By writing out the gamma reaction rate equations and estimated the excitation rates, the optimum process has been found.
► The effect of the laser intensity and repetition rates is explained.
► The maximum activity of 2257 Bq is produced which is higher than produced 125Sn by proton beam.