JPS58161854A - Radiation analysis - Google Patents

Abstract

PURPOSE:To obtain the distribution of a specific element about any transverse section in a non-distruction and non-contact manner by rotating a radiation source centered on a test piece so that a radiation beam can scan a required transverse section of the test piece given times from different directions. CONSTITUTION:A radiation 14 irradiates a test piece 1 and the intensity of fluorescent X ray 15 of a specified wavelength is detected 16 about those fluorescent X rays 15 radiated from the test piece 1 to perform an element analysis of the test piece 1. A radiation source 12 is rotated centered on the test piece 1 so that a radiation beam 14 scans a required transverse section 2 of the test piece 1 at least three times from different directions and detects 16 the intensity distribution along the scan line of the fluorescent X rays 15 of the specified wavelength at each scanning to be memorized into a computer 25. A plurality of intensity distributions thus obtained are computed and synthesized with the computer 25 to determine a distribution of elements corresponding to the X ray 15 of the specified wavelength on the transverse section 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an analysis method for performing elemental analysis using radiation such as X-rays and γ-rays.

There are cases where it is necessary to know the state of publication of a specific element in an arbitrary cross section of a plate, rod, or block-like specimen.

For example, the distribution of Zn, etc. in carbon bricks at the bottom of a blast furnace that have deteriorated due to use provides a powerful clue to elucidating the deterioration mechanism. In addition, Mn in continuous slabs
, S, etc. are useful for analyzing the formation of the central segregation zone.

By knowing the distribution of specific elements in several cross sections, it is possible to further obtain the three-dimensional distribution of elements in the test specimen, and it is possible to proceed effectively with the above-mentioned analysis.

Conventionally, it has been difficult to obtain the three-dimensional distribution of elements as described above. For any cross section, the specimen can be sliced into thin slices for analysis. However, depending on the material of the test specimen, it may be brittle and difficult to slice, or in some cases, the cut surface may break or change in quality during slicing, making it impossible to preserve the internal state of the test specimen as it is. Therefore, it is desirable to know the elemental distribution of any cross section of such test specimens in a non-destructive manner.

This invention was made to solve the above-mentioned problems in general radiation analysis methods, and provides a radiation analysis method that can obtain the distribution of specific elements in any cross section of a specimen in a non-destructive and non-contact manner. This is what I am trying to do.

This invention applies the techniques of X-ray transmission computed tomography (often used in medical applications) and fluorescence X-ray analysis. That is, the radiation source is rotated about the specimen for each scan so that the radiation beam scans the required cross-section of the specimen at least three times from different directions. The test specimen emits fluorescent X-rays when irradiated with radiation. For each scan, the intensity distribution of fluorescent X-rays of a specific wavelength along the scanning line is detected and stored in the computer. Then, the obtained plurality of intensity distributions are computationally synthesized in the computer to determine the distribution of elements corresponding to the fluorescent X-rays of the specific wavelength in the cross section.

As described above, in the radiation analysis method of the present invention, the distribution of a specific fluorine can be determined in any cross section of a test specimen in a non-destructive and non-contact manner. Therefore, even if the material is difficult to slice as described above, it is possible to perform the horizontal analysis on the required cross section. Moreover, if the distribution of elements is obtained for a plurality of cross sections, it is also possible to obtain a three-dimensional distribution of the elements.

In the present invention, either a wavelength dispersion method or an energy dispersion method may be used to detect fluorescent X-rays of a specific wavelength.

Moreover, the number of elements to be detected may be one or two or more. Furthermore, the distribution of a specific element may be displayed graphically on an image reproducing device, or the distribution may be shown numerically and the numerical values printed out using a printer.

Below, 20% of carbon bricks are stored using the energy dispersion method.
The present invention will be described in detail by taking as an example the case where the distribution of .

Figure 1 shows carbon brick I (I refractory brick for blast furnace bottom)
2 is a schematic diagram showing a state in which a cross section 2 of is analyzed by the method of the present invention. As shown in the drawing, a narrow beam of X-rays 14 is emitted from the X-ray tube 12.

(The atoms in the carbon brick 1 are excited by the irradiation with X-rays, and X-rays unique to each element, that is, the optical X-rays 15 are generated and emitted.) A detector 16 is arranged to detect the fluorescent X-ray beam 15.

To obtain the distribution of Zn on the cross section 2 of the brick 1, first the beam 14 is passed through the desired cross section 2, and
The pair of wire tube 12 and detector 16 is moved as one along straight line 5. During this movement, the detector 16 detects the fluorescent X-rays 15 emitted from the brick 1.

The detected value a of the optical X-ray 15 is input to the buffer memory 26 of the computer 5 via an amplifier 21 and a multi-channel analyzer 22, as shown in FIG. In the multi-channel analyzer 22, a specific X-ray (in this example, Z
α, : 1.435^) is selected from the characteristic X-rays of n. Then, the intensity of the specific X-ray detected in this manner is stored in correspondence with the moving distance of the detector 16 from the scanning starting point 6 shown in FIG. That is, the buffer memory 26
The intensity distribution of the fluorescent light X and line 15 along the scanning direction is stored.

The intensity stored in the buffer memory 26 is stored in the central processing unit (
In the CPU) 27, calculation processing is performed so as to be back projected onto the cross section 2 of the brick 1. For example, as shown in FIG. 3(a), the detected intensity ■ is uniformly distributed on the cross section 2 along the direction perpendicular to the scanning direction S in proportion to the intensity ■. The distributed values represent the shading of the image when it is reproduced. For example, CR with 16 levels of gray scale.
It is displayed on T.

When the first scan of the cross section 2 is completed as described above, the radiation irradiation device 11 and the 160 pairs of detectors are rotated around the brick l in the extended plane of the cross section 2, and the direction of the X-ray beam 14 is Same as the first time (scan the shank).

Repeat the above operations in order to obtain the results shown in Figure 3 (a), fly),
(C) A back projection image as shown in... is obtained.

These back-projected images are superimposed by arithmetic processing in the CPU 27 and stored in the main memory 28. The superimposed image B as shown in FIG.
It represents the concentration corresponding to ntt. A clear distribution cannot be obtained unless the number of scans is at least three times or more.

The image is composed of, for example, 512 x 512 pixels, and each pixel is displayed in 16 gray scales as described above. The main memo IJ 28 stores pixels corresponding to respective addresses in a two-dimensional arrangement. Incidentally, as shown in FIG. 4, blurring of the image occurs around the image B, but this can be removed by filtering the detected intensity by calculation in the CPU 27. For example, the size of one pixel is 1 mm x l
It is mm.

1 The image stored in the memo IJ 28 is read out by the reading device 4 and converted into an analog signal by the digital-to-analog converter 31. The analog signal passes through the amplifier 32 to C
It is input to the RT 35 and an image showing the distribution of Zn in the cross section 2 of the brick 1 is displayed.

Arithmetic processing in the computer 27 is executed according to the program read out from the program store 30h.

In the above embodiment, the multi-channel analyzer 22 electrically spectrally separates the optical X-rays to determine the distribution of a specific original voice. However, in this invention, it is also possible to apply a wavelength-separating method that optically separates fluorescent X-rays as in the case of the anterior nose.

As shown in FIG. 5, the fluorescent X-rays 14 emitted from the specimen 1 pass through the slit 17 and are diffracted in the spectroscopic crystal 18. The spectroscopic crystal 18 and the detector 19 are arranged so as to detect the characteristic X-rays of the element to be analyzed. In other words, only X-rays that meet the flag conditions are effectively diffracted,
Spectroscopic crystal to reach the detector 19! 8 and detector 19
The angle between As the detector 19, a proportional counter or a scintillation counter is used.

The signal from the detector 19 is input to the pulse-hide analyzer 2.1 via an amplifier 21, where noise signals such as high-order X-rays are removed. The signals from the pulse/hide analyzer 24 are input to the computer 5 via an analog/digital converter 25/. The subsequent signal processing is the same as in the case of the energy dispersion method.

FIG. 6 explains another method of scanning the cross section of the test specimen I.

In FIG. 1, one detector 16 corresponds to the X-ray tube 12, forming a pair. On the other hand, in FIG. 6 1), a plurality of detectors 37 are combined with the X-ray tube 12 to scan the specimen l. This scanning method can reduce the number of scans. FIG. 6 (In Ron, a large number of detectors 38 are arranged in an arc shape facing the X-ray tube 12. The X-ray tube 12 and the detector 38 rotate around the test specimen 1 as a pair. Figure 6 (
In c), a large number of detectors 39 are arranged all around the test specimen l. In this case, the detector 39 is fixed and
Only the wire tube 12 is rotated around the test specimen l. With any of these methods, the test specimen I can be scanned at high speed.

Note that the radiation mentioned in the present invention includes X-rays, 'γ-rays,
Refers to beta rays and neutron rays. X-rays are the most practical and convenient to use, but they have the disadvantage of poor penetrating power when the specimen is thick or made of elements with high atomic numbers, and are effective when the specimen is thin and light. . R-rays are also practical, but require strict radiation control. Fluorescence X that also occurs
If the energy of the ray is weak, it may be absorbed within the test body and measurement may take a long time, so care must be taken.

Furthermore, when displaying an image of the distribution of a plurality of elements, it is convenient to display each element in a different color. Furthermore, in the case of image display, the element amounts are displayed with a range using the gray scale. The exact value of the elemental amount is displayed numerically. In order to ensure accurate and highly accurate analysis of the target element, it is desirable to calibrate using a standard sample whose analytical values are available, as is done in normal analytical techniques.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram for explaining radiation irradiation and detection in this invention, FIG. 2 is a block diagram of an apparatus for carrying out the method of this invention using an energy dispersion method, and FIG. 3 is a diagram for explaining an image back projection method. Fig. 4 is a drawing explaining the principle of image formation by the back projection method, Fig. 5 is a block diagram of an apparatus for carrying out the method of the present invention using a wavelength dispersion method, and Fig. 6 is a cross-sectional view of a test specimen. 3 is a diagram illustrating a scanning method. l...Test specimen, 12--X-ray, 16 p 19 p 3
7 p 38 p39...X@detection unit, 17...slit, 18--spectroscopic crystal, 22-φ multi-channel analyzer, -pulse hide analyzer, 5...computer, 35--image display device. Patent Applicant Representative Patent Attorney Tomomi Yafuki (and 1 other person) Figure 1 322- Figure 3 Figure 4

Claims (1)

[Claims] In this method, the elemental analysis of the specimen is performed by irradiating the specimen with radiation and detecting the intensity of the fluorescent X-rays emitted from the specimen at a specific wavelength. The radiation source is rotated around the specimen so that the cross section of the specimen is scanned at least three times from different directions, and for each scan, the intensity distribution along the scanning line of fluorescent X-rays of a specific wavelength is detected and analyzed. A radiation analysis method, characterized in that the intensity distributions are stored in a computer, the obtained plurality of intensity distributions are computationally synthesized in the computer, and the distribution of the element corresponding to the fluorescence Xa of the specific wavelength in the cross section is determined.