Samples of different solid materials as well as of water and soil were exposed to the stray radiation field created by a 28.5-GeV electron beam hitting a copper dump. After irradiation, specific activities and residual dose rates were measured at different cooling times from 1 h up to several months. Furthermore, the irradiation experiment was simulated with the FLUKA Monte Carlo code. The calculations included a detailed identification of interaction processes creating the different nuclides. First comparisons of experimental data on specific activities and FLUKA results indicate underestimation by FLUKA at irradiation locations laterally to the target, while the agreement seems reasonable downstream of it. The irradiation experiment, the current status of the data analysis, and a preliminary comparison with FLUKA results are presented.