Model RD-150 SAMMobile | How can I determine if I need a 2x4x16 or a 4x4x16 inch NaI detector?
Model RD-150 SAMMobile | How can I determine if I need a 2x4x16 or a 4x4x16 inch NaI detector?
BNC generally recommends a 2x4x16 inch detector unless greater efficiency is needed at high photon energies. For energies that include photons from U-235 and Pu-239 there is negligible difference between the two sizes. This means that the photons from both U-235 and Pu-239 are fully absorbed in either size detector. For isotopes like Cs-137 and U-238 some differences begin to show. The photon energy at 2615 keV (which is an indication of highly enriched material) is still easily detected in the 2x4x16 inch detector because the background is quite low in this region. Contact the factory for application specific support. The data for several common isotopes is shown below:
|
2x4x16 |
4x4x16 |
|
100% absorption (abs) at 186 keV (includes all energies of U-235) 87% abs at 414 keV (includes Pu-239 at 332, 375 and 414 keV) 75% abs at 662 keV (Cs-137) 67% abs at 1000 keV (U-238) 52% abs at 2615 keV |
100% abs at 186 keV (includes all energies of U-235) 98% abs at 414 keV (includes all energies of Pu-239) 95% abs at 662 keV (Cs-137) 89% abs at 1000 keV (U-238) 76% abs at 2615 keV |