A Passive Neutron Dosimeter Design and Test
H. R. Vega-Carrillo
Active neutron dosimeters suffer from dead time and pulse pileup in very intensive neutron fields. However, in very weak neutron fields, long time measurements are required to reach good statistics. A Monte Carlo calculation, using MCNP code, was performed to determine the response of a passive neutron dosimeter made of a 25.4-cm-diameter, high-density polyethylene sphere with a TLD600 located at the center. The response was compared with responses of other widely used dosimeters like SNOOPY, Leake, and PNR-4. The dosimeter was built with four TLDs: two TLD600s and two TLD700s. From thermal to 1 MeV, the relative neutron dosimeter's response was lower than with a Leake or PNR-4. However, it was larger than with a SNOOPY from thermal to 0.1 MeV. An experimental test was performed with neutron fields from a bare Cf-252, heavy water moderated Cf-252 and inside the vault of a PET cyclotron where neutron dose was measured and results were compared with measurements done with a Bonner sphere neutron spectrometer. For all neutron sources used, the neutron dose measured was statistically the same as the neutron dose measured with the Bonner sphere neutron spectrometer.
This abstract was presented at the 32nd Annual Midyear Meeting, "Creation and Future Legacy of Stockpile Stewardship Isotope Production, Applications, and Consumption", Poster Session, 1/24/1999 - 1/27/1999, held in Albuquerque, NM.