After a week involuntarily taken off due to technical difficulties, I narrate my visit on 3 October to the open day at the Heinz MaierâLeibnitz Neutron Source in Garching, north of Munich. The âsourceâ is a specialized nuclear reactor (but the people in charge of it will thank you not to talk about that), otherwise known as FRMâII, the successor to the original ForschungsâReaktor MĂŒnchen (Munich Research Reactor), built by American Machine & Foundry in 1957, and noted at the time for its ellipsoidal aluminium dome. The campus of the Technical University of Munich was subsequently built around this reactor.