A low-energy HPGe detector dedicated to radioactivity measurements far below the environmental levels
Successive background reduction factors of a low background, semiplanar Germanium detector were achieved at sea level and underground locations with various shielding conditions. The optimal working conditions, achieved at a depth of 500 m water equivalent (m w.e.) lead to a background reduction factor of about 100 in the energy region from 5 keV to 1000 keV in comparison with a measurement at sea level. The integral count rate as low as 0.00361 +/-0.00004 s[-1} over this energy interval is mainly attributable to the influence of the cosmic rays but also to the residuals of the natural decay chains, radon and progenies, man made radionuclides and cosmogenic activation in detector and shielding materials. About one event per day, or less, corresponding to the gamma rays of interest, are recorded in energy intervals of four times the full width at half maximum (FWHM) resolution of the detector. Detection limits were deduced for Pb-210 and uranium metal activities. Materials studied are: clay, uranium metal, biological matrix exposed to radon flux; gold and silver foils, lead and copper badges.
Bibliographic Reference: Paper presented: International Committee for Radionuclide Metrology, Seville (ES), October 2-6, 1995
Availability: Available from (1) as Paper EN 39451 ORA
Record Number: 199512090 / Last updated on: 1996-01-15
Original language: en
Available languages: en