Als top-off simulation studies for radiation safety

We plan to commission top-off injection[1,2] at the advanced light source (ALS[3]) in the near future. In order to guarantee radiation safety, we need to exclude the possibility of injecting electrons into the users' photon beam lines because of the very high radiation doses involved in case of such an event. This issue must carefully investigated and experimental tests cannot be easily performed. The only reliable way is through simulation. We have developed a scheme based in exhaustive simulations that accounts for all possible dangerous scenarios and that at the same time requires a reasonable amount of computing time. This paper describes such a method and presents a summary of the studies performed for the ALS at the present time.