Merjenje ionizirajočega sevanja is an elective course for third-year undergraduates in the FMF physics program, with a focus on students considering a career in experimental particle physics. These notes are from the summer semester of the 2020-21 academic year, when the course was taught by professor Boštjan Golob (lecture) and dr. Luka Šantelj (exercises). Material covered in the course includes: