Monitoring bremsstrahlung from 4 MeV electrons by nuclear excitation and Al2O3 thermoluminescence dosemeters.
Isomer excitation by gamma,gamma' reactions and aluminium oxide thermoluminescence dosemeters (TLDs) have been used to monitor bremsstrahlung from the 4 MeV electron beam of a linear accelerator type LPR4 produced on a 0.9 mm Pt converter foil. Natural indium and osmium as well as TLDs have been irradiated at different distances (2-11 cm) and angles (0 degrees-90 degrees). Dose rates measured by TLDs were 5-110 kGy x h(-1). Isomer excitation of 115In (half-life 4.5 h) was used for monitoring bremsstrahlung of energies above 1 MeV, while that of 189Os (half-life 5.8 h) extended the available range down to 200 keV. Isomer production yields measured by gamma spectrometry and found to be about 10(-19)-10(-18) Bq per nucleus were calibrated against dose rate. A graphical method based on a semiempirical formula was used to evaluate the bremsstrahlung flux as well as the dose rate from the activity of isomeric monitors with uncertainties below 20%. The method is simple, of linear response in a large scale, independent of temperature, and able to monitor extremely high gamma intensities.
Institute of Isotope and Surface Chemistry, Budapest, Hungary.
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NC
Tam
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Lakosi
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Osvay
D000537:Aluminum Oxide / Q000737:chemistry*; D004583:Electrons; D005720:Gamma Rays; D008027:Light; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods*; D013696:Temperature
D000537:Aluminum Oxide