Lead-paint detector
OwnerLee Grodzinsinventor
Life of this patent
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Abstract
A new type of X-ray fluorescence detector of lead paint that utilizes the measured intensities of fluorescent L.sub..alpha. and L.sub..beta. x-ray lines of lead to determine the absolute concentration of lead in mg/cm.sup.2, independent of either the thickness or the nature of the covering layers non-lead paint. The lead-paint detector uses a source of initiating photons whose energy is in a specific range, a detector of the characteristic lead L x-rays with sufficient energy resolution to detect the L.sub..alpha. and L.sub..beta. rays separately, a signal processor, and an appropriate read-out. The lead-paint detector will improve the rapidity and accuracy of lead paint measurements in a very cost-effective manner.
Claims9
A method for measuring the areal density, of a target element near the surface of a substrate, the target element capable of emitting L.sub..alpha. and L.sub..beta. x-rays when suitably excited, the target element being covered by layers of covering material that do not contain the target element, comprising the steps of:
- inducing L.sub..alpha. and L.sub..beta. x-rays from said target element by means of an appropriate excitation radiation means so that the L.sub..alpha. and L.sub..beta. x-rays are emitted from said surface;
- detecting said L.sub..alpha. and L.sub..beta. x-rays with a detector having sufficient energy resolution to measure the intensity of the L.sub..alpha. and L.sub..beta. x-rays separately, using the measured intensities of the L.sub..alpha. and L.sub..beta. x-rays to calculate the areal density of said target element by means of the following equation:
- ##EQU7## wherein m.sub.Z is the areal density of said target element, I.sub.L.sbsb..alpha. and I.sub.L.sbsb..beta. are the measured intensities of the L.sub..alpha. and L.sub..beta. x-rays emitted by the target element, I.sub.L.sbsb..alpha.S and I.sub.L.sbsb..alpha.S are the measured intensities of the L.sub..alpha. and I.sub..beta. x-rays emitted by a standard of known areal density of the target element, R.sub.1 is the ratio of mass attenuation coefficients for the L.sub..alpha. to the L.sub..beta. x-rays and is effectively the same value for all materials, and R.sub.2 is the ratio of the mass attenuation coefficients for the initiating radiation to the L.sub..beta. radiation and is effectively the same value for all materials.
A method for measuring the areal density of a target element near the surface of a substrate, the target element capable of of emitting L.sub..beta. and L.sub..gamma. x-rays when suitable exited, the target element being covered by layers of covering material that do not contain the target element, comprising the steps of:
- inducing L.sub..beta. and L.sub..gamma. x-rays from said target element by means of an appropriate excitation radiation means so that the L.sub..beta. and L.sub..gamma. x-rays are emitted from said surface;
- detecting said L.sub..beta. and L.sub..gamma. x-rays with a detector having sufficient energy resolution to measure the intensity of the L.sub..beta. and L.sub..gamma. x-rays separately, using the measured intensities of the L.sub..beta. and L.sub..gamma. x-rays to calculate the areal density of said target element by means of the following equation:
- ##EQU8## wherein m.sub.Z is the areal density of said target element, I.sub.L.sbsb..beta. and I.sub.L.sbsb..gamma. are the measured intensities of the L.sub..beta. and L.sub..gamma. x-rays emitted by the target element, I.sub.L.sbsb..beta.S and I.sub.L.sbsb..gamma.S are the measured intensities of the L.sub..beta. and I.sub..gamma. x-rays emitted by a standard of known areal density of the target element, R.sub.3 is the ratio of mass attenuation coefficients for the L.sub..beta. to the L.sub..gamma. x-rays and is effectively the same value for all materials and R.sub.4 is the ratio of the mass attenuation coefficients for the initiating radiation to the L.sub..gamma. radiation and is effectively the same value for all materials.
Dependencies are inferred from the claim text.