Ralf Kaiser studied Physics and Mathematics at the University of Münster, Germany, and obtained his PhD in experimental High Energy Physics from Simon Fraser University, Vancouver, based on research carried out at the Canadian National Laboratory TRIUMF. After a postdoctoral fellowship at the German National Laboratory DESY in Hamburg, he was appointed to a faculty position in the Nuclear Physics Group at the University of Glasgow in 2001. For almost 20 years his research was focused on the fundamental structure of matter and on the design and construction of the detectors required for this research.

In 2010 he joined the IAEA as Head of the Physics Section, responsible for the IAEA programmes on Accelerator Applications, Nuclear Instrumentation and Nuclear Fusion. In this role he represented the Agency on the ITER and SESAME Councils. After the accident in Fukushima, he participated in a series of Missions to Fukushima, as leader and expert member, and he led the development of a UAV-based radiation monitoring and mapping system for Fukushima Prefecture.

In 2016 he founded Lynkeos Technology as a spin-off from the University of Glasgow, to commercialise the use of cosmic-ray muon imaging for nuclear waste containers. Lynkeos has deployed the first CE-marked muon imaging system at Sellafield in the UK in 2018, and has won a series of awards including the 2018 Institute of Physics Business StartUp Award. Ralf is a Fellow of the Royal Society of Edinburgh since 2020.