Collaborative project results in the construction of a second UCN source at the TRIGA research reactor in Mainz / Blueprint for Munich-based high-efficiency source. Researchers from the Technical University of Munich (TUM) and Johannes Gutenberg University Mainz (JGU) have opened a new chapter in their long-standing collaboration concerning the generation of ultra-cold neutrons (UCN). A second source of ultra-cold neutrons has recently been installed at the TRIGA research reactor in Mainz. In initial tests, this source has been delivering excellent results. Neutrons are the neutral particles that form part of the atomic nucleus. In unbound form, as so-called free neutrons, they are unstable and decay rapidly. Experiments with ultra-cold neutrons are of special relevance for fundamental research in physics, particularly in the fields of cosmology and particle physics. For this purpose, free neutrons are cooled to very low temperatures, slowing down their movement to a level where they can be stored in special containers.