Measuring the ²⁰⁸Tl range of E ≤ 116 keV in silver films

In this study, measurements of the effective range of ²⁰⁸Tl ions (E ≤ 116 keV) emanating from the recoil daughters from ²²⁰Rn were carried out. The target used was a set of thin silver films. The amount of the stopped ²⁰⁸Tl ions in each film was determined by measuring the short-lived (~3 m) β activity of ²⁰⁸Tl, where the effective range was found to be 11.8 ± 2.36 µg/cm². This value is in agreement (~20%) with Monte Carlo simulations using SRIM-TRIM software. These simulations also included the attenuation of ²⁰⁸Tl ions caused by the interaction of the ions with the Al sheet holding the ²⁰⁸Tl ion source. After adding the weakened ²⁰⁸Tl source to the simulation, the resulting width of the simulated spectrum was in agreement with experiment (to within 4.5%).