Methods and apparatus for performance verification and stabilization of radiation detection devices

Abstract

The rare earth metal Lutetium in compound form is used in check sources of various shapes and sizes to calibrate and tune radiation detection devices. Radioactive Lutetium-176, a naturally occurring (non man-made) isotope forming part of the Lutetium compound, produces gamma energies of approximately 90, 200, and 300 kilo-electron Volts which are used in the calibration. Such gamma energies are close to the predominant spectral lines of special nuclear materials such as U-235 and Pu-239, which is to be monitored by radiation detection devices. Lutetium in a radioactive calibration source (which is either integrated into the radiation detection device or positioned close to it during calibration) provides benefits including that no reactor or accelerator is required during production or use, for the creation of man-made radioactivity, no dangerous radiation exposure occurs and (because of the long half-life of Lu- 176) the radioactive calibration source essentially never needs to be replaced. Moreover, the handling of such a source is much less restrictive and costly than that of a conventional man-made radioactive isotope.

Description

technical field [0001] This invention relates to radiation sources for calibrating radiation detection devices, and more particularly to lutetium-containing inspection sources, their manufacture and their use. Background technique [0002] The US Department of Homeland Security requirements include the need for devices capable of sensitive detection of gamma radiation emitted from concealed radioactive materials (eg, according to American National Standards Institute (ANSI) standards such as ANSIN 42.32). Many steel mills and scrap yards are also concerned about potentially hazardous meltdowns known as orphan sources, which may be contained within or exported from scrap. Even garbage and waste incinerators have monitors on their doors and personnel to detect this radiant energy. Commercially available highly sensitive portable or mobile gamma radiometers can be configured to detect very small amounts of radiant energy. [0003] Some conventional radiation detection instrum...

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However, since the average gamma energies of these isotopes are significantly higher than typical for those isot

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