Dosimeters called passive are dosimeters that do not need an external source of energy to operate. They are integrating dosimeters, that is to say they do not give an estimate of an overall dose. They do not normally allow estimating maximum instantaneous doses.
They are regulatory dosimeters that must be worn on the chest by a worker that may be exposed to ionizing radiation. Extremity dosimeters are also recommended when hands, for example, would be particularly exposed to radiation.
For this reason, they tend to be replaced by active dosimeters, but they retain a place in the general monitoring of large staffs.
Passive dosimeters were the first to be developed and were initially derived from photographic techniques, the same ones that led to the discovery of radioactivity by Becquerel in 1896. These dosimeters, today more commonly called dosifilms, tend to disappear owing to changes in regulations and the incoming demise of silver film.
The dosifilms are gradually replaced by dosimeters using more efficient and modern technologies measuring the light emission or luminescence of the irradiated detector. The technologies used for measuring luminescence are OSL (Optically Stimulated Luminescence), TLD (Thermo Luminescence) and RPL (Radio Photo Luminescence). The luminescence is triggered by a light flash in the case of the OSL and RPL and heating for TLD.
The OSL and TLD are, to date, passive dosimetry techniques recognized by the French legislation together with the dosifilms dosimeters.
Access to page in french