US 4,283,625 AGranted

X-Ray fluorescence analysis

AssigneeAssociated Metals & Minerals Corporation

InventorThomas C. King

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Abstract

A sample is analyzed for the presence of an element by exposing it to radiation which causes the element to emit a characteristic radiation. Background radiation and the characteristic radiation are passed through a first filter which attenuates the characteristic radiation. The time required for a fixed amount of radiation to pass through the first filter is measured to establish a reference time. Radiation from the sample is then passed through a second filter which attenuates the characteristic radiation by an amount different from the first filter. The amount of radiation passing through the second filter is measured during a time interval substantially equal to the reference time. The difference between the two amounts of radiation indicates the amount of element in the sample and reduces errors due to samples of different composition and physical condition and due to variation of radiation intensity from the source.

Claims24

Dependent claims

Apparatus for reducing the effects of sample composition and physical condition, and variation of radiation intensity from a source used to analyze a sample for the presence of an element which fluoresces characteristic radiation when exposed to a source of radiation, the apparatus comprising:

means for holding the sample;
means for irradiating the sample with a radiation of sufficient energy to cause the element to fluoresce the characteristic radiation;
a first filter which substantially attenuates the characteristic radiation;
a second filter which attenuates the characteristic radiation less than the first filter;
means for sensing radiation from the sample;
means for measuring the time required for the radiation sensing means to sense a fixed amount of radiation from the sample when one of the filters is between the sample and radiation sensing means to establish a reference time;
means for measuring the amount of radiation from the sample reaching the sensing means during a time interval substantially equal to the reference time when the other filter is disposed between the sample and the sensing means;
and
means for determining the difference between the two amounts of radiation reaching the sensing means through the two filters to indicate the amount of the element in the sample.

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Dependencies are inferred from the claim text.