This is a work in progress and it is about the appropriation processes that take place when a scientific instrument is mobilized from a place to another. In 1950 the Mexican Government increased the budget of the Physics Institute of the National Autonomous University of Mexico (UNAM) to buy a 2 MeV electrostatic generator Van de Graaff. This instrument was bought at the High Voltage Engineering Corporation (HVEC). Its acquisition involved several processes: the approach to it, due to links between Mexican and American scientists; the negotiation undertook by important members of Mexican scientists to get the funding; the training of Mexican researchers at the Laboratory for Nuclear Science and Engineering (LNSE), MIT and the HVEC; the design and construction of complementary instruments in order to solve difficulties that took place in the local context. The establishment of the research activities was mainly divided in two: One related to the techniques for the experiments on light elements related to the suggestions and training of the American physicist William Buechner from the LNSE at MIT and the physicist Thomas Bonner from Rice University; the other was the work done on radioactive rain due to the recommendations made by United Nations Scientific Committee on the Effects of Atomic Radiation.