JPS6029897B2 - X-ray shielding device for fluorescent X-ray analyzer - Google Patents

Description

[Detailed description of the invention] An arbitrary sample to be analyzed is irradiated with X-rays to generate crab light X-rays, and the wavelength of the crab light X-rays is analyzed by output wave height analysis of an X-ray spectrometer or X-ray detector. By detecting with a circuit or the like, it is possible to know the substance contained in the sample or the amount thereof.

In such a crab light X-ray analyzer, in order to prevent the primary X-rays irradiated from the X-ray tube to the sample from leaking outside and causing danger, it is necessary to close the gap between the X-ray tube and the sample. They must be connected with an X-ray shielding tube so that X-rays can pass through the inside. However, when the X-rays passing through this shield tube enter the inner surface of the shield tube, crab light X-rays from the material that formed the shield tube are generated, which mix with the crab light X-rays of the sample and are detected by a spectrometer, etc. Because it is incident, it causes erroneous observations. Therefore, in the past, it was necessary to make the diameter of the shielding cylinder extremely large to prevent the primary X-rays from entering, and this had the disadvantage that the apparatus could not be made compact and lightweight. The present invention seeks to obviate the above-mentioned drawbacks. FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, in which a target 2 of an X-ray tube 1 is made of copper, tungsten, or other suitable material, and an X-ray window made of beryum or the like is formed on the side wall facing the target. 3 is provided.
That is, when a high-velocity electron beam is incident on the target 2 from the thermionic emission cathode 4, primary X-rays are generated from the target, and the X-rays are projected to the outside through the window 3.
An annular raised wall 5 is formed around the window 3. A sample chamber 7 is provided in the upper part of the X-ray spectrometer 6, and a plate-shaped sample 9 attached to a removable lid 8 and perpendicular to the plane of the paper is placed inside the sample chamber 7. A primary X-ray entrance window 10 is formed in this sample chamber 7 so as to face the sample 9, and an X-ray shielding tube 11 is removably screwed into the window. The shielding tube 11 consists of an inner tube 12 and an outer tube 13 that are coaxially superimposed, and an auxiliary shielding tube 14 is loosely iron-coupled to the outside thereof, and the collar 16 of the auxiliary shielding tube is attached to the collar 15 of the outer tube. They are made to face each other and are pressed against each other by a spring 17. Although the inner tube 12 is made of the same material as the target 2 of the X-ray tube, it can be pulled out from the outer tube 13 as shown in FIG. That is, at least the inner surface of the X-ray shielding tube 11 is made of the same material as the target 2 of the X-ray tube, but by forming the shielding tube as a double part so that the inner tube 12 can be inserted and removed, When the X-ray tube 1 is replaced, an inner tube made of the same material as the target 2 can be selected and used. The auxiliary shielding tube 14 is iron-fitted to the raised wall 5 with the tip of the shielding tube 11 facing the window 3 of the X-ray tube. Therefore, even if the X-ray tube 1 is slightly tilted or tilted from a predetermined position with respect to the axis of the X-ray shielding tube 11, the auxiliary shielding tube 14 can be closely fitted to the raised wall 5. Therefore, it is possible to reliably prevent X-rays from leaking outside and posing a danger to the operator. As described above, in the present invention, an X-ray shielding cylinder 11 is provided between the window 3 of the X-ray tube and the sample 9, and the inner surface of this shielding cylinder is made of the same material as the target 2.

Therefore, the X-rays projected from the window 3 of the X-ray tube pass through the shielding tube 11 in the axial direction as indicated by the broken line a, and enter the sample 9, which excites the sample and generates the crab-beam X-rays b. generate. A part of this crab light X-ray b enters the spectroscope 6 and its wavelength is detected. Moreover, if the shielding tube 11 is made small, a portion a' of the X-rays projected from the window 3 will be incident on the inner surface of the shielding tube. A portion of this incident X-ray a' is scattered and enters the sample, exciting the sample. Therefore, the intensity of the excitation X-rays incident on the sample is increased, and a large amount of crab-like X-rays can be generated, thereby improving analysis accuracy. Further, a part of the incident X-rays a' excites the substance on the inner surface of the shielding cylinder 1, and generates crab-like X-rays. However, since the inner surface of the shield tube is made of the same material as the target 2 of the X-ray tube, the crab light X-rays contain wavelengths other than those included in the excitation X-rays a projected from the X-ray tube I. Does not include wavelength components. Therefore, the crab light X-rays generated on the inner surface of the shield tube 11 are scattered by the sample surface, etc., and the spectrometer 6
Even if the beam were to be incident on the beam, there would be no risk of causing an erroneous observation. As explained above, since the apparatus of the present invention provides a shielding tube between the X-ray tube and the analysis sample, it is possible to prevent danger due to leakage of X-rays.
Moreover, not only is there no risk of erroneous observation due to the incidence of primary X-rays for sample excitation on the inner surface of the shielding tube, but also the intensity of the crab-light X-rays generated from the sample is increased, thereby improving analysis accuracy. Therefore, the above-mentioned shielding tube can be configured to be extremely small and lightweight.
A line analyzer can be manufactured. Moreover, by making the shielding tube a double structure and replacing its inner tube, the substance on the inner surface of the shielding tube can be easily matched to the target of the X-ray tube used.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, and FIG. 2 is an exploded longitudinal sectional view of the shielding cylinder in FIG. 1. In the figure, 1 is the X-ray tube, 2 is the target, and 3 is the X-ray tube.
ray window, 4 is a thermionic emission cathode, 5 is a raised wall, 6 is an X-ray spectrometer, 4 is a sample chamber, 8 is a lid body, 9 is a sample, 10 is a window, 11
12 is an X-ray shielding cylinder, 12 is an inner cylinder, 13 is an outer cylinder, 14 is an auxiliary shielding cylinder, 15 and 16 are collars, and 17 is a spring. So/'a Atsushi Shio

Claims (1)

[Scope of Claims] 1. A fluorescent X-ray analyzer that analyzes components contained in a sample by irradiating the sample with excitation X-rays and detecting the wavelength of fluorescent X-rays generated from the sample. An X-ray shielding cylinder is provided between the sample and the window of the X-ray tube that generates X-rays for sample excitation, and is arranged so that the X-rays for sample excitation pass through the tube in the axial direction. An X-ray shielding device characterized in that the inner surface of the X-ray shielding cylinder is made of the same material as the target of the X-ray tube. 2. The fluorescence according to claim 1, wherein the shielding tube is composed of an inner tube and an outer tube that are coaxially superposed and can be freely inserted and removed, and the inner tube is made of the same material as the target of the X-ray tube. X-ray shielding device for X-ray analyzer.