The modern understanding of radiation got its start in 1895 with X-rays discovered by Wilhelm Röntgen, followed in 1896 by Henri Becquerel’s discovery of radioactivity. The development of the study of radiation opened a vast field of research concerning various disciplines: chemistry, physics, biology, geology, sociology, ethics, etc. Additionally, new branches of knowledge were created, such as atomic and nuclear physics that enabled an in-depth knowledge of the matter. Moreover, during the historical evolution of this body of knowledge a wide variety of new technologies was emerging. This article seeks to analyze the characteristics of experimental research in radioactivity and microphysics, in particular the relationship experience-theory. It will also be emphasized that for more than two decades, since the discovery of radioactivity, experiments took place without the theory being able to follow experimental dynamics. Some aspects identified as structural features of scientific research in the area of radiation and matter will be addressed through historical examples. The inventiveness of experiments in parallel with the emergence of quantum mechanics, the formation of teams and their relationship with technology developed from the experiments, as well as the evolution of microphysics in the sense of “Big Science” will be the main structural characteristics here focused. The case study of research in radioactivity in Portugal that assumes a certain importance and has structural characteristics similar to those of Europe will be presented.