Real-Time Monitoring of Astatine-211 Production by Alpha Particle Bombardment*

Iterative calculations were utilized to achieve real-time monitoring of astatine-211 (At-211) production from 28.8 MeV alpha particles hitting bismuth-209 causing the Bi-209(a,2n)At-211 nuclear reaction using target current readings. Real-time measurements are crucial for determining optimal beam irradiation times, especially given At-211's short half-life of 7.2 hours and its sensitivity to beam intensity fluctuations. This helps beam operators better understand when beam irradiation on the target is completed. The current was monitored on the aluminum-backed bismuth target every 5 seconds during irradiation using a picoammeter. This current correlates directly with the beam flux calibrated using previous Faraday cup measurements. A Python script incorporating: radioisotope production equations, cross-section data from NNDC and SRIM, bismuth properties, and real-time current data provides estimates of At-211 activity and predictive capabilities. The script generates an updating graph of activity over time, a value display of estimated present At-211 activity, and a predictability function of bombardment durations to achieve desired activity levels, providing valuable feedback for beam operators. Further work will better calibrate the At-211 production monitoring, this system has a standard deviation of 10% the target activity when used for full-length bombardment when compared to "End-of-Bombardment" values collected from a dose calibrator..