There's no single inventor of the radiation dosimeter, as its development involved contributions from multiple scientists and engineers over a long period. However, some key figures and milestones in its history include:

* 1896: Henri Becquerel discovered radioactivity, laying the foundation for measuring radiation levels.

* 1908: Stefan Meyer and Edgar Regener developed the first ionization chamber, a device that measures ionization caused by radiation.

* 1912: Hermann Fricke developed the first chemical dosimeter, which utilized chemical reactions to measure radiation exposure.

* 1920s: Wilhelm Wien and Hans Geiger developed the Geiger-Müller tube, a sensitive detector for ionizing radiation.

* 1930s: Herbert L. Anderson and Charles D. Anderson developed the ionization chamber used in the Manhattan Project.

* 1940s: Harold E. Johns and Edwin R. Epp developed the first commercially available film dosimeter, which utilized photographic film to record radiation exposure.

Therefore, it's more accurate to consider the development of the radiation dosimeter as a collaborative effort, with contributions from numerous scientists and engineers over several decades.

It's also important to note that the development of specific types of dosimeters, such as thermoluminescent dosimeters (TLDs) and electronic personal dosimeters (EPDs), involved further contributions from various individuals and institutions.