JP2003344544A - Detector for fluorescent x-rays, fluorescent x-ray detector and x-ray fluorescence analyzer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect low energy X-rays of very light elements with sufficient sensitivity, and enable detection for a wide measurement range from a very light element region to an intermediate element region, with sufficient sensitivity. <P>SOLUTION: This detector for fluorescent X-rays is a gas flow type proportion counter tube provided with an inlet and an outlet of counter gas, an incidence window of X-rays, and an electrode of a core line. The counter tube is made thin in the X-ray incident direction, and the core line is arranged adjacently to the window. Gas is ionized by low energy fluorescent X-rays in the whole tube. An ionized current proportional to X-ray energy is detected with the electrode of the core line, and the low energy X-rays of the very light elements is detected with sufficient sensitivity. A plurality of core lines are arranged to the plane of incidence of X-rays, thereby increasing the amount of detection signal and enhancing detection sensitivity. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to fluorescent X-ray analysis, and relates to a fluorescent X-ray detector used for fluorescent X-ray analysis, a fluorescent X-ray detector, and a fluorescent X-ray analyzer.

[0002]

2. Description of the Related Art X-ray detectors include a proportional counter utilizing ionization, an ionization chamber, a GM counter, a scintillation counter utilizing fluorescence, a fluorescent plate, and a Si (Li) detector utilizing semiconductors. There are Ge (Li) detectors, dry plates and films that utilize the photographic effect. Generally, a proportional counter is used for the wavelength dispersive X-ray spectrometer, and a Si (Li) detector is used for the energy dispersive X-ray spectrometer.

X-rays that have entered the inert gas ionize the gas atoms and ionize them. X-rays can be detected by collecting these ions at the electrodes and counting them as electric pulses. The ion collection status changes depending on the level of the voltage applied to the electrodes. A proportional region is used for X-ray detection utilizing the ionization effect of an inert gas. In this proportional region, an ionizing current proportional to the X-ray energy flows, and the X-rays can be separated by energy.

The proportional counter is a gas flow type proportional counter (F-PC) that counts while flowing gas by supplying an inert gas, and a sealed proportional counter that seals gas ( S-PC; Sealed pro
portional counter). P-10 gas (mixed gas of 90% Ar + 10% CH4) and P-20 gas (mixed gas of He + CO2) are used for the gas flow type proportional counter, and are suitable for counting long wavelength X-rays of 5 Å or more. There is. Further, xenon (Xe), neon (Ne), argon (Ar), krypton (Kr) gas, or the like is used for the enclosed proportional counter, which is used for counting hard X-rays of 5 Å or less.

FIG. 4 is a schematic view for explaining the structure of a gas flow type proportional counter, FIG. 4 (a) is a view seen from the entrance side, and FIG. 4 (b) is in the X-ray entrance direction. Cross section along,
FIG. 4C is a sectional view in a direction orthogonal to the core wire.

In the gas flow type proportional counter 100, a core wire 102 constituting an electrode is provided inside a counter tube 101 via an insulator 108, and an X-ray entrance window 10 through which X-rays enter.
4, an X-ray emission window 105 through which X-rays are emitted, an inflow port 106 through which a counting gas flows in and out, an outflow port 107, and the like. Also,
A solar slit 114 is provided in front of the X-ray entrance window 104.

The solar slit 114 and the X-ray entrance window 1
The X-rays incident via 04 ionize the counting gas introduced into the counting tube 101. Among the electron-ion pairs generated by ionization, the electrons are absorbed by the core wire of the positive electrode and the positive ions are absorbed by the side wall. The incident X-ray is detected by detecting the generated electric pulse.

[0008]

The conventional gas flow type proportional counter has a structure in which the intermediate element regions such as Ca and K are changed to B,
The same detector is used to count ultra-light element regions such as C, N, and O. The X-ray energy in the ultra-light source region is, for example, 0.183 eV in B-Ka, whereas the X-ray energy in the intermediate element region is, for example, Ca-ka.
Then, it is 3.691 eV, which is about 20 in terms of energy difference.
There is a double difference. The conventional gas flow type proportional counter detects X-rays including such a large energy difference with one detector.

Low-energy X-rays can cause the ionizing action of the counting gas only in the vicinity of the X-ray entrance window of the detector. Therefore, when the detector is configured to detect the X-ray energy of the intermediate element region, the low-energy X-ray of the ultralight element cannot be detected with sufficient sensitivity. Therefore, it is difficult to cover from the intermediate element region to the ultra-light element region with one detector.

Therefore, the present invention aims to solve the above-mentioned conventional problems and detect low-energy X-rays of ultra-light elements with sufficient sensitivity, and to broaden the range from the ultra-light element region to the intermediate element region. The purpose is to detect the measurement range with sufficient sensitivity.

[0011]

The present invention provides a fluorescent X-ray detector, a fluorescent X-ray detector using the fluorescent X-ray detector,
And a fluorescent X-ray analyzer including the fluorescent X-ray detector, in which the counter of the fluorescent X-ray detector commonly provided by the detectors detects low-energy X-rays of ultra-light elements with sufficient sensitivity. It is what

The fluorescent X-ray detector of the present invention is a gas flow type proportional counter having a counting gas inlet and outlet, an X-ray entrance window, and a core wire electrode. On the other hand, the core wire is thin and the core wire is placed close to the X-ray entrance window. The gas is ionized by low-energy fluorescent X-rays throughout the tube, and an ionizing current proportional to the X-ray energy is generated by the core electrode. To detect. With this configuration,
Low energy X-rays of ultra-light elements can be detected with sufficient sensitivity.

The fluorescent X-ray detector of the present invention has a structure in which a plurality of core wires are arranged on the X-ray incident surface. X
It is possible to increase the detection signal amount by arranging a plurality of core wires with respect to the incident surface of the line and detecting with the plurality of core wires, and thereby to increase the detection sensitivity.

Further, the fluorescent X-ray detector of the present invention has a structure in which a metal partition wall is arranged between a plurality of core wires with respect to the X-ray incident surface. By surrounding multiple core wires with metal partition walls,
The electric field surrounding the core wire becomes uniform, which can enhance the detection sensitivity.

The fluorescent X-ray detector of the present invention is constructed by using the above-mentioned fluorescent X-ray detector. The fluorescent X-ray detector is arranged in the preceding stage to count ultra-light elements. Further, by disposing a fluorescent X-ray detector that counts light elements and intermediate elements in the subsequent stage of the fluorescent X-ray detector in the previous stage,
Two types of fluorescent X-ray detectors having different detection energy regions are arranged in series. With this configuration, the ultra-light element is counted from the ultra-light element region to the light-element region by counting the ultra-light element with the fluorescent X-ray detector in the preceding stage and counting the light element and the intermediate element with the detector for the fluorescent X-ray in the subsequent stage. It is possible to detect with high detection sensitivity in a wide range of the element region.

Further, in the fluorescent X-ray detector of the present invention, the reduced pressure counting gas is flown into either one of the front and rear fluorescent X-ray detectors, and the atmospheric pressure counting gas is flown into the other. The pressure of the counting gas supplied to the fluorescent X-ray detectors in the front and rear stages is made different,
Each detection condition can be set individually and optimized for analytical purposes. Also, the gas species of the counting gas supplied to the fluorescent X-ray detectors in the front and rear stages may be different.

The fluorescent X-ray analysis apparatus of the present invention is provided with the above-mentioned fluorescent X-ray detector to perform fluorescent analysis with high detection sensitivity in a wide range from the ultra-light element region to the light element region and the intermediate element region. You can

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. 1 and 2 are schematic cross-sectional views for explaining a fluorescent X-ray detector of the present invention and a fluorescent X-ray detector constituting the fluorescent X-ray detector, and FIG. 1 shows a core wire of the X-ray detector. FIG. 2 shows a cross-sectional state in a direction orthogonal to each other, and FIG. 2 shows a cross-sectional state along the arrangement direction of the core wire. Further, FIG. 3 is a front view seen from the X-ray side.

In FIGS. 1 and 2, a fluorescent X-ray detector 1 of the present invention has a first fluorescent X-ray detector 2 arranged in series from the X-ray side to the emission side in a front stage and in a rear stage. Second fluorescence X
The line detector 3 is arranged and configured. A solar slit 4 is provided in front of the first fluorescent X-ray detector 2. Here, the first fluorescent X-ray detector 2 is a detector for detecting fluorescent X-rays in the ultra-light element region, and the second fluorescent X-ray detector 3 is in the light element region to the intermediate element region. Fluorescent X
It is a detector that detects lines.

The first fluorescent X-ray detector 2 is composed of a gas flow type proportional counter, a counting gas inlet 26 and an outlet 27 are provided on the wall surface of the counter 21, and an X-ray side X-ray is provided.
A line entrance window 24 is provided, and an X-ray exit window 25 is provided on the second fluorescent X-ray detector 3 side in the subsequent stage. Each window is covered with a polyester or polypropylene film. A core wire 22 is stretched inside the counter tube 21 via an insulating member 28.
A predetermined voltage can be applied between the core wire 22 and the inner wall surface of the counter tube 21. A positive electrode is connected to the core wire 22 by connecting the positive side of a power source, and absorbs electrons in an electron-ion pair generated by ionization by incident X-rays. On the other hand, by connecting (or grounding) the negative side of the power source to the inner wall surface of the counter tube 21, the ions in the electron-ion pair are absorbed. The electrons absorbed by the electrode of the core wire 22 are amplified as an electric pulse signal by an amplifier (not shown), and then are incident X by signal processing by a wave height analyzer or a counter.
Detect lines.

The first fluorescent X-ray detector 2 includes a counter tube 21.
Is thin with respect to the X-ray incident direction, the core wire 22 is arranged close to the X-ray incident window 24, and the counting gas is ionized by the low-energy fluorescent X-rays in the entire tube 21. For example, ultra-light elements such as Be, B, C, N and O are detected. The X-rays that have passed through the inside of the counting tube 21 pass through the X-ray emission window 25 and are incident on the second fluorescent X-ray detector 3 arranged in the subsequent stage.

As shown in FIGS. 1 and 3, the first fluorescent X-ray detector 2 may have a plurality of core wires 22a to 22c, and the plurality of core wires 22a to 22c.
The detected X-ray dose can be improved by summing and counting the detection signals of.

With this configuration, the first fluorescent X-ray detector 2
The S / N ratio can be improved by increasing the amount of ionizing current detected by the whole. Each of the plurality of core wires 22a to 22c is provided with partition walls 23a and 23b between the respective core wires, and the plurality of counter tubes 2 are provided.
1a to 21c may be formed. According to this configuration, it is possible to change the type of counting gas supplied to each of the counting tubes 21a to 21c and the voltage applied to the core wires 22a to 22c, and the X-ray detection conditions of each counting tube can be made uniform. Besides, X-ray detection conditions can be set for each counter tube. The counter tubes 21a to 21c may be provided with X-ray entrance windows 24a to 24c and X-ray exit windows 25a to 25c corresponding to the core wires 22a to 22c, respectively. Further, by making the partitions 23a and 23b made of metal, the counter tubes 21a to 21c can be electrically separated, and the electric field around the core wires 22a to 22c can be made uniform.

By making the first fluorescent X-ray detector 2 thin against the incidence of X-rays, the ionization of low-energy fluorescent X-rays can be performed not only in the vicinity of the surface layer of the X-ray entrance window but also in the entire counter tube. And the low energy fluorescent X-rays are counted effectively. Furthermore, by supplying a low-pressure gas other than the atmospheric pressure gas, the counting efficiency of low-energy fluorescent X-rays can be increased.

Like the first fluorescent X-ray detector 2, the second fluorescent X-ray detector 3 can also be constituted by a gas flow type proportional counter, and counts on the wall surface portion of the counter tube 31. A gas inlet 36 and a gas outlet 37 are provided, an X-ray entrance window 34 is provided on the X-ray entrance side, and an X-ray exit window 35 is provided on the rear side, and a polyester or polypropylene film is provided on each window. . Further, a core wire 32 is stretched inside the counter tube 31 via an insulating member 38, and a predetermined voltage is applied between the core wire 32 and the inner wall surface of the counter tube 31.

Similar to the first fluorescent X-ray detector 2, the core 32 is connected to the positive side of the power source to form a positive electrode,
The electrons in the electron-ion pair generated by the ionization by the incident X-rays are absorbed, and the negative wall of the power source is connected (or grounded) to the inner wall surface of the counter tube 31, whereby the electrons-
Absorbs ions in the ion pair. The electrons absorbed by the electrode of the core wire 32 are amplified as an electric pulse signal by an amplifier (not shown), and then the incident X-ray is detected by signal processing by a wave height analyzer or a counter.

The second fluorescent X-ray detector 3 includes a counter tube 31.
Has a diameter suitable for detecting light elements such as Na to Ca and intermediate elements such as Ti to Zn. The second fluorescent X-ray detector 3 may have the same structure as the conventional fluorescent X-ray detector except for the solar slit.

The fluorescent X-ray detector of the present invention is a combination of a first fluorescent X-ray detector arranged in the preceding stage and a second fluorescent X-ray detector arranged in the latter stage, and the super light element is detected in the former stage. By detecting and detecting intermediate elements from light elements in the latter stage,
The counting sensitivity can be improved. The light elements are
The detection amount of the fluorescent X-ray detector in the preceding stage and the detection amount of the fluorescent X-ray detector in the succeeding stage are summed up to be obtained.

Further, the fluorescent X-ray detector of the present invention has a two-stage structure of a detector in the ultra-light element region and a detector in the light element to intermediate element region, and supplies depressurized counting gas to one of them. However, it is possible to provide a difference in the pressure of the counting gas, such as supplying the counting gas at normal pressure to the other, and, for example, P-10 gas (a mixed gas of 90% Ar + 10% CH4) or P- 20 gas (mixed gas of He + CO2)
Can be supplied and another gas can be supplied to the other, and the voltage applied to the core wire can be set separately, so that the optimum conditions can be set according to the purpose of analysis.

Further, according to the present invention, an X-ray fluorescence analyzer can be constructed by using the above X-ray fluorescence detector.
It is possible to perform fluorescent X-ray analysis with sufficient sensitivity in a wide measurement range from the ultra-light element region to the intermediate element region.

In the above example, a plurality of core wires and three counter tubes are arranged, but the present invention is not limited to this number example, and any number can be set. .

As described above, according to the present invention,
Low energy X-rays of ultra-light elements can be detected with sufficient sensitivity, and a wide measurement range from the ultra-light element region to the intermediate element region can be detected with sufficient sensitivity.

[0032]

[Brief description of drawings]

FIG. 1 is a diagram showing a cross-sectional state of a fluorescent X-ray detector of the present invention in a direction orthogonal to a core wire.

FIG. 2 is a diagram showing a cross-sectional state along the arrangement direction of core wires of the fluorescent X-ray detector of the present invention.

FIG. 3 is a front view of the fluorescent X-ray detector of the present invention viewed from the X-ray incident side.

FIG. 4 is a schematic diagram for explaining a configuration of a conventional gas flow type proportional counter.

[Explanation of symbols]

1 ... Fluorescent X-ray detector, 2 ... First fluorescent X-ray detector, 3 ...
Second fluorescent X-ray detector 4, solar slit 21,
21a to 21c ... Counter tube, 22, 22a to 22c ... Core wire, 23a, 23b ... Partition wall, 24, 24a to 24c ... X
Line entrance window, 25, 25a to 25c ... X-ray exit window, 26 ...
Inflow port, 27 ... Outflow port, 28 ... Insulating member, 31 ... Counter tube, 32 ... Core wire, 34 ... X-ray entrance window, 35 ... X-ray exit window, 36 ... Inflow port, 37 ... Outflow port, 38 ... Insulating member 1
01 ... Counter tube, 102 ... Core wire, 104 ... X-ray entrance window, 1
05 ... X-ray emission window, 106 ... Inflow port, 107 ... Outflow port,
108 ... Insulating member, 114 ... Solar slit.

Continued front page    F-term (reference) 2G001 AA01 BA04 CA01 DA01 DA02                       DA06 DA10 GA01 GA09 KA01                       NA16                 2G088 EE30 FF03 FF15 GG02 JJ01                       JJ08 JJ09 JJ15 JJ31                 5C038 DD02 DD04 DD06

Claims (6)

[Claims] 1. A gas flow type proportional counter having a counting gas inlet and outlet, an X-ray entrance window, and a core wire electrode, wherein the counter tube is thin relative to the X-ray entrance direction, and X
The core wire is placed close to the line entrance window, and the counting gas is ionized by low-energy fluorescent X-rays in the entire tube.
A fluorescent X-ray detector characterized in that an ionization current proportional to linear energy is detected by a core wire electrode. 2. The fluorescent X-ray detector according to claim 1, wherein a plurality of core wires are arranged with respect to an X-ray incident surface. 3. The fluorescent X-ray according to claim 2, wherein a metal partition wall is arranged between the plurality of core wires with respect to the X-ray incident surface to make the electric field around the core wires uniform. Detector. 4. Fluorescent X for counting ultra-light elements and counting light elements and / or intermediate elements by arranging the fluorescent X-ray detector according to claim 1 in a preceding stage. An X-ray fluorescence detector characterized in that two types of X-ray fluorescence detectors having different detection energy regions are arranged in series by arranging the X-ray detector in the subsequent stage. 5. A former fluorescent X-ray detector and a latter fluorescent X-ray detector.
5. The reduced pressure counting gas flows into any one of the line detectors, and the atmospheric pressure counting gas flows into the other detector.
X-ray fluorescence detector described in 1. 6. An X-ray fluorescence analyzer comprising the X-ray fluorescence detector according to claim 4 or 5.