Photoactivation and photoneutron activation analysis

摘要: Abstract For the last two years 3 MeV Van de Graaff electron accelerator at Shell Development Company, Emeryville, California, has been in routine use neutron activation analysis. Over 30 elements can be analyzed for, some parts per million range and macro concentrations. The kW beam produces bremsstrahlung a gold target photons, turn, liberate neutrons from large (15 cm cube) beryllium block immersed moderator. thermal flux available volume of over liters is more than 5 × 10 7 /cm 2 sec. Twenty-four samples 25 ml each irradiated simultaneously. activities produced are measured instrumentally scintillation counter using gamma ray spectroscopy. Several same sample may distinguished by taking advantage differences half-life energy. Recently it found possible to extend scope analysis activating directly with photons. Eighteen metastable isomers stable nuclides have produced, for first time direct photoactivation. Bremsstrahlung allowed act on samples. Although sensitivities lower, method specific activation, many cases interferences eliminated photons alone. Applications photoactivation other chemical (1) energy measurement (2) dosimetry.