Calibration of a Tld Albedo Individual Neutron Monitor

Neutron individual monitoring is considerably less established than photon individual monitoring. The main difficulty is the impossibility to find a detector that covers the large occupational neutron energy range. All commercial individual monitors have strong energy dependence. Another difficulty is to calibrate an individual neutron monitor in the ISO 21909 established energy operational range: from thermal to 20 MeV. Since 1983, IRD uses a TLD one-component albedo neutron monitor, which has to be calibrated specifically for each neutron field. To improve its energy response, a two-component albedo monitor was developed, which measure the thermal neutron component besides the albedo one. Using the ratio between both components, it is possible to make some energy response correction. However, the construction of this energy correction curve depends on the accessing of several different traceable calibration fields that are not easily available. The twocomponent monitor has already been calibrated in reference neutron fields: thermal, 5 accelerator-produced monoenergetic beams (70, 144, 565, 1200 and 5000 keV) and 5 radionuclide sources (Cf, Cf(D2O), AmBe, Am-B and Pu-Be) at several distances. Four different energy correction curves have been adjusted for use with different neutron sources. Nowadays, the neutron system is in test for routine application. Its main application is occupational neutron monitoring of workers who handle neutron sources at different distances and moderation, such as well logging and calibration facilities.