Sensitivity Problems in Biological and Environmental Counting

Analysis of biological and environmental samples differs from other physics applications in the need for very high sensitivity. A number of factors, including efficiency, geometry, resolution, and an interrelation of these, all affect sensitivity. An analysis, based on both experimental data and computations, indicates that in the range of equal detector volumes < 40 cm3, planar detectors are to be preferred over coaxial detectors due to their much better ability to quantitate data at energies below 500 keV without loss of performance at higher energies. For equal detector volumes in excess of 40 cm3, coaxial detectors may be preferred for high energy use due to their better resolution, but performance at lower energies will still favor the planar detectors.