FI71618C - SAETT ATT MEDELST ROENTGENSTRAOLNING MAETA HALTEN AV ETT FOERUTBESTAEMT AEMNE I ETT PROV. - Google Patents

Description

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C (45) Paten tti '..y j ..;. C tty I Pater t: -2.1 Olat U 01: .007 (51) Kv.lk.' / Int.Cl. * G 01 N 23/223 ENGLISH FINLAND (21) Patent application - Patentansökning 80227 ^ (22) Application date - Ansökningsdag 18.0 7.80 <EN) (23) Starting date - Giltighetsdag 18.07.80 (41) Published public - Blivit offentlig 19.01 .82

National Board of Patents and Registration (44) Date of publication and date of publication. -

Patent and registration authorities Ansökan utlagd och utl.skriften publicerad 10.10.86 (86) Kv. application - Int. trap (32) (33) (31) Privilege claimed - Begärd priority (71) (72) Nils Johannes Backlund, Sunnevik, Oskarshamn, Sweden-Sverige (SE) (7 * 0 Tampere Patent Office (5 * 0 Method for determining the concentration of a specified substance) to be measured in an experimental batch by means of X-rays - Sätt att medelst röntgenstralning rotting sharks in the form of X-rays

The invention relates to a method for measuring the concentration of a predetermined substance in a test batch by means of X-rays. The analyzer using the method must be portable.

When monochromatic X-rays hit a test batch from which the concentration of a particular substance is to be measured, only those X-ray lines in the test batch that have a wavelength greater than the wavelength of the incoming X-rays will fluoresce. For this reason, activation of heavy substances has generally been avoided because it is difficult to separate the radiation using a known filtration technique.

It is known that wavelength analysis or sorting can be enhanced by using a flat crystal and a sight telescope or a curved crystal. However, these two methods have the disadvantage that fluorescence radiation can only be utilized in a small fraction, since only one millionth of the radiation hits the detector.

Although germanium detectors are capable of satisfactorily analyzing wavelengths, they must be continuously cooled with liquid oxygen in order to function satisfactorily. For this reason, said detectors are not suitable for use with portable devices.

Replacing a fluorescent filter would provide good analysis and high intensity, but this procedure is limited by the inability to take advantage of occasional absorption discontinuities or edges and the fact that for practical reasons it is not possible to make filters for all materials.

It is therefore an object of the present invention to provide an improved method which can be applied using a portable analyzer.

This invention relates to a method for measuring the concentration of a predetermined substance in an experimental batch by X-ray by determining the intensity of fluorescence radiation of said substance. The method according to the invention is characterized in that the test batch is irradiated in part with primary radiation containing wavelengths longer than the absorption edge of the test batch with the substance being measured but shorter than the absorption edge with those test batch substances which may interfere with the test batch. wherein the test beam emits a first combined fluorescence radiation whose intensity is measured, and that the test beam is irradiated with a primary beam containing at least wavelengths shorter than the absorption edge of the substance to be measured, the test beam emitting a second combined fluorescence radiation having an intensity then the intensity of the first combined radiation is subtracted from the intensity of the second combined radiation and the difference in intensity between them is calculated,

II

3 71 61 8 wherein the intensities or durations of the primary radiations are preselected so that both primary radiations give the same fluorescence dose from the test batches to a substance with an absorption edge longer than the substance whose concentration is being measured.

It is clear that the use of the method depends on the choice of the wavelength of the primary radiation. The shorter wavelength primary radiation should be as short as possible at the absorption edge or discontinuity point, while the longer wavelength primary radiation should be as short as possible at the absorption edge or discontinuity point. Thus, there is a more indeterminate difference between said two wavelengths, although the differences between the absorption edge and the shorter wavelength and the absorption edge and the longer wavelength are as small as possible.

According to one embodiment of the invention, the longer wavelength primary radiation is monochromatic radiation, the wavelength of which is denoted by the letter Λ, and the shorter wavelength primary radiation is monochromatic radiation, the wavelength of which is Λ -d, where the letter d denotes the difference between longer and shorter a. Alternatively, said longer wavelength radiation is monochromatic radiation, the wavelength of which is denoted by the letter Λ, and the shorter wavelength radiation is a combined radiation consisting of wavelengths A and Λ -d, where the letter d denotes the difference between the longer and shorter wavelengths.

The method according to the invention can be applied using an X-ray tube, the anode of which consists of a mixture of two substances, i.e. a so-called alloy anode. Alternatively, two separate X-ray tubes may be used or a tube with two separate anodes may be used. The test batch is initially irradiated with a primary beam of a longer wavelength. If an X-ray tube with an alloy is used, the radiation is first

Claims (5)

4 71 61 8 through a datator to filter radiation of shorter wavelengths. The intensity of fluorescence caused by radiation of longer wavelength is then measured. In the next step, the test batch is irradiated at both said wavelengths and the intensity of the combined fluorescence is measured, said combined intensity now also including intensities caused by shorter wavelength radiation, unlike in the first measurement. The intensity of the combined fluorescence generated by the primary radiation of longer wavelength is then subtracted from the intensity of the combined fluorescence obtained by irradiating the test batch with radiation of shorter and longer wavelengths. The difference thus obtained is the intensity of the fluorescence of the shortest wavelength which can be excited using said shorter primary radiation. When using the method according to the invention, it is important to note that the intensity of the primary radiation must be determined in such a way that the same fluorescence intensity is obtained for the substance in both primary irradiation wavelength ranges. A method for measuring the concentration of a predetermined substance in a test batch by X-ray by determining the X-ray intensity, characterized in that the test batch is partially irradiated with primary radiation containing wavelengths longer than the absorption edge of the test batch as the absorption edge of the test batch substances which may interfere with the measurement, in which case the first combined fluorescence radiation of the test beam is excited and the test beam is irradiated with primary radiation containing at least the wavelengths shorter than the absorption edge of the substance to be measured, wherein the test batch emits a second combined fluorescence radiation, the intensity of which is measured, after which the intensity of the first combined radiation II 71618 is subtracted from the intensity of the second combined radiation and the intensity difference between them is calculated, whereby the primary radiation The intensities or durations of these substances are pre-selected so that both primary radiations give the same fluorescence dose from the test lots to a substance with an absorption edge longer than the substance whose concentration is being measured. A method according to claim 1, characterized in that the longer wavelength primary radiation is monochromatic radiation, the wavelength of which is denoted by the letter A, and the shorter wavelength primary radiation is monochromatic radiation of wavelength A -d, where the letter d denotes the difference between longer and shorter a. A method according to claim 1, characterized in that the longer wavelength radiation is monochromatic radiation, the wavelength of which is denoted by the letter A, and the shorter wavelength radiation is a combined radiation consisting of wavelengths A and A -d, where the letter d denotes the longer and shorter wavelengths. the difference. 1. The provisions of this Regulation do not apply to X-ray fluorescence in the presence of high-intensity X-ray fluorescence, the results of which have been shown to be the primary means of absorption, In the case of an absorber in the form of an absorber in the form of an absorber in the form of an absorber in the form of an absorber, ämne vars sharks mätes, varigenom