PRINCIPLES of XRF

The X-ray fluorescence (XRF) spectrometer uses gamma ray bombardment to produce nuclear excitement of atoms within the test material. Upon relaxation of each excited atom, a characteristic X-ray is emitted which is proportional to the atomic number of the excited atom.  By analyzing the spectral X-ray intensities, the types of elements present and their respective concentrations can be determined.  This technique has been successfully used to measure any number of material properties including chemical composition, density, moisture content, material thickness during manufacturing, contamination, and of course locating hazardous materials such as lead-based paint.  This method is used by Warrington’s microLEAD I XRF spectrometer to provide a nondestructive test method that is portable, performed in situ, and requires only a few seconds for each test making it ideal for on-site testing of lead-based paint where each house may require measurements on 80 to 100 different components to validate a lead-free housing certification.

microLEAD I Spectrometer

The microLEAD I XRF spectrometer uses a button capsule of Cobalt 57 for the gamma excitation source.  The decay of this low energy radioactive isotope produces a relatively monochromatic beam of 122 keV gamma photons. This energy is directed into the painted surface and is capable of penetrating through 40 or more layers of typical paint. The atoms present in the paint matrix fluoresce from interaction with the gamma energy and emit characteristic X-rays which are processed by the microLEAD I using microcomputer controlled electronics and high resolution spectral filtering technology.

The microLEAD I is designed to detect the high energy K-shell X-rays which have a low attenuation rate when passing through overlying layers of paint.  This ensures accurate detection of lead-based paint that has been covered by many layers of non-lead paint.  Because of the inherent inaccuracy and high false negative rate of L-shell measurements on lead-based paint, only K-shell analysis should be used for the measurement of record to provide a lead-safe certification.

Portable X-ray Fluorescence

By using a radioisotope source, X-ray fluorescence is available in a lightweight handheld package suitable for battery operated field work.   The microLEAD I has been approved for distribution to general licensees, which in most states eliminates the need and expense for a specific radioactive material license by the operator. Since Warrington distributes factory direct to private businesses and government agencies, additional information concerning radioactive material licenses, training seminars, and lease purchase options can be obtained by directly contacting Warrington, Inc.