JP5553300B2 - X-ray fluorescence inspection apparatus and fluorescence x-ray inspection method - Google Patents

Description

  The present invention relates to a fluorescent X-ray inspection apparatus and a fluorescent X-ray inspection method for detecting a foreign substance contained in a subject.

  In recent years, secondary batteries such as lithium ion batteries have attracted attention due to environmental problems and energy problems. Lithium ion secondary batteries include, for example, a positive electrode in which a positive electrode active material such as lithium cobaltate (LiCoO2) or lithium manganate (LiMn2O4) is pasted on a current collector together with a binder, a negative electrode such as graphite, and a porous polyethylene film. The separator and the non-aqueous electrolyte are housed in a battery container. However, when foreign matter (metal particles) other than the positive electrode active material is mixed into the positive electrode, there arises a problem that the foreign matter breaks through the separator and short-circuits. For example, if the foreign matter contains iron, it is difficult to remove it by aging, and the electromotive force varies, so it is necessary to detect and remove even a small foreign matter.

Therefore, a technique for irradiating one surface of the positive electrode with X-rays and determining the presence or absence of foreign matter from the obtained transmission image is disclosed (Patent Document 1).
Further, a technique for obtaining sufficient detection intensity by irradiating one surface of the positive electrode with X-rays and integrating and detecting the fluorescent X-rays emitted from the upper and lower surfaces of the positive electrode is disclosed (Patent Document 2). .

JP 2006-179424 A JP 2003-14670 A (0025, Examples)

  However, the technique described in Patent Document 1 is a transmission-type foreign matter inspection, and it is difficult to selectively detect foreign matter including an element that leads to deterioration in battery quality. In the case of the technique described in Patent Document 2, since the energy of the X-ray source (Rh / Cr target tube) is in a wide range, both Co in lithium cobaltate, which is a constituent element of the positive electrode, and Fe, which is a foreign substance, are both present. A photoelectric effect is produced. Therefore, the tail of the fluorescent X-ray spectrum of Co interferes with the fluorescent X-ray spectrum of Fe, and the detection sensitivity of foreign matter (Fe) cannot be sufficiently obtained. If the detection sensitivity is not sufficient, the detection takes a lot of time, and the productivity of the battery decreases.

  The present invention has been made to solve the above-described problem, and can detect a foreign substance containing a specific element selectively, and can detect the foreign substance while moving the subject. It is another object of the present invention to provide a fluorescent X-ray inspection method.

In order to achieve the above object, the fluorescent X-ray inspection apparatus of the present invention detects a foreign substance contained in a moving subject, and an atomic number of one element constituting the subject constitutes the foreign substance. Applied when the atomic number of one element is greater, a radiation source that irradiates the subject with primary radiation, and fluorescent X-rays emitted from one element that constitutes the foreign matter by the irradiation of the primary radiation The primary radiation when the energy of the K absorption edge of one element constituting the subject is E1, and the energy of the K absorption edge of one element constituting the foreign substance is E2. Has an energy peak EP, and E2 <EP <E1.
In this way, the photoelectric effect of the elements constituting the subject (sample) is suppressed, and the generation of fluorescent X-rays serving as detection noise is suppressed, so that the foreign substance detection sensitivity is improved. Moreover, since the energy of primary radiation exceeds E2, the photoelectric effect of a foreign material can be caused effectively. In this way, foreign matter detection with good sensitivity can be performed, so that the measurement time can be shortened. From the above, it becomes possible to detect a foreign substance contained in a moving subject that has been difficult in the past.

The apparatus may further include a rate meter that outputs a count rate of the fluorescent X-rays detected by the detector, and a signal processing unit that determines that a foreign substance is present when the count rate exceeds a threshold value.
The signal processing means may determine that there is a foreign object when the time when the count rate exceeds the threshold is a predetermined time or more.

Storage means for storing energy of K absorption edges and Kα fluorescence X-rays of a plurality of elements including the foreign matter and the elements constituting the subject, and the energy peak EP of the primary radiation associated with the radiation source And reading means for reading out the radiation source satisfying the relationship of E2 <EP <E1 from the storage means when one element constituting the subject and one element constituting the foreign substance are designated, It is preferable to provide display means for displaying the radiation source read by the reading means.
In this way, since the radiation source satisfying the relationship of E2 <EP <E1 corresponding to the designated subject and foreign matter is displayed, the operator can select an appropriate radiation source and perform measurement.

Preferably, the element constituting the subject is Co, and one element constituting the foreign substance is Fe, and the primary radiation includes characteristic X-rays of Ni.
It is preferable that the element constituting the specimen is Mn, one element constituting the foreign matter is Cr, and the primary radiation includes Fe characteristic X-rays.
It is preferable to use ¹⁸¹ W or ⁵⁷ Co in which the element constituting the specimen is Mn, one element constituting the foreign substance is Cr, and the radiation source is a radioisotope.

  The fluorescent X-ray inspection method of the present invention detects a foreign matter contained in a moving subject, and the atomic number of one element constituting the subject is larger than the atomic number of one element constituting the foreign matter When the energy at the K absorption edge of one element constituting the object is E1, and the energy at the K absorption edge of one element constituting the foreign substance is E2, the energy peak EP is given, and E2 < A process of irradiating the subject with primary radiation satisfying EP <E1, and a process of detecting fluorescent X-rays emitted from one element constituting the foreign substance by the irradiation of the primary radiation.

  According to the present invention, it is possible to selectively detect a foreign substance containing a specific element, and the foreign object can be detected while moving the subject.

1 is a block diagram showing a configuration of a fluorescent X-ray analyzer according to an embodiment of the present invention. It is a figure which shows the relationship between the mass absorption coefficient of one element (Co) and foreign material (Fe) which comprise a test object, and energy. It is a figure which shows the fluorescent X ray spectrum by the fluorescent X ray inspection apparatus of this invention. It is a figure which shows the fluorescence X-ray spectrum by the conventional fluorescence X-ray inspection apparatus. It is a figure which shows the relationship between the mass absorption coefficient and energy of one element (Mn) and the foreign material (Cr) constituting the object. It is a figure which shows the data structure of the element table memorize | stored in the memory | storage means. It is a figure which shows the data structure of the radiation source table memorize | stored in the memory | storage means. It is a figure which shows the flow of the display process of the radiation source 10 by CPU. It is a block diagram which shows the structure of a detector. It is a block diagram which shows another structure of a detector. It is a figure which shows the method of judging that the foreign material existed when the count rate exceeded the threshold value. It is a figure which shows the process through which a primary radiation and fluorescent X-ray pass a subject.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a fluorescent X-ray inspection apparatus 1 according to an embodiment of the present invention. The fluorescent X-ray inspection apparatus 1 includes a radiation source 10, a detector 12 that detects fluorescent X-rays, a rate meter 14 that outputs a count rate of fluorescent X-rays detected by the detector 12, and a personal computer 20. ing. The primary radiation from the radiation source 10 is collected by the lens 10 </ b> A, and then irradiated to the subject (the positive electrode plate of the Li ion battery) 100 that is placed on the transport device (conveyor 200) and moves in the L direction. The The detector 12 receives power from the detector power supply 12A, detects fluorescent X-rays emitted from the subject 100 (and the foreign matter 110 in the subject) by the irradiation of primary radiation, and supplies the rate meter 14 with the detection result. Output. The rate meter 14 analogly outputs the detected fluorescent X-rays as a count number (count rate) per unit time.
As the radiation source 10, an X-ray tube (sphere) having a target or an irradiation apparatus using a predetermined radioisotope can be used as a primary radiation source. The lens 10A collects the radiation diffused from the radiation source 10 to increase the density, and a capillary or a crystal can be used. The detector 12 will be described later.

The personal computer 20 includes a CPU (central processing unit) 22 that controls the whole, a RAM and ROM 23, a storage means 24 including a hard disk, an input means (keyboard) 26, a display means (monitor) 28, and a signal input / output (not shown). Section, an A / D converter, a D / A converter, a clock, and the like, and a program stored in advance in the ROM 23 or the like is executed by the CPU 22.
As will be described later, the personal computer 20 (CPU 22) reads the radiation source type suitable for the measurement from the storage means 24, displays the radiation source type on the monitor 28, and is output from the rate meter 14. The counting rate is acquired, and it is determined whether or not a predetermined threshold is exceeded. Therefore, the CPU 22 corresponds to “reading means”, “display means”, and “signal processing means” in the claims.

Next, the features of the present invention will be described with reference to FIG. FIG. 2 is a diagram showing the relationship between the mass absorption coefficient and energy of one element (Co) and foreign matter (Fe) constituting the specimen. In FIG. 2, Co has an atomic number one larger than Fe.
In the following description, the sample 100 is a positive electrode plate in which a positive electrode active material made of lithium cobalt oxide (LiCoO ₂ ) is pasted on a current collector, and the foreign material 110 is mainly Fe. At this time, the main components of the subject 100 are Li, Co, and O (oxygen), but the element that adversely affects the detection of Fe (foreign matter) in the fluorescent X-ray analysis (becomes detection noise) has an atomic number. Co becomes one larger than Fe.

  In FIG. 2, it is known that the mass absorption coefficient of each element rapidly increases when the energy of primary radiation becomes equal to or higher than the element-specific value called absorption edge, and the transmittance of primary radiation decreases. is there. For example, in the case of Fe, when the energy is less than E2, the mass absorption coefficient is small, but when the energy becomes E2, the mass absorption coefficient increases rapidly, and when the energy exceeds E2, the mass absorption coefficient is attenuated little by little. This is because the K shell photoelectric effect of Fe atoms occurs at energy E2 or higher. Therefore, at energy E2 or higher, a photoelectric effect occurs in the K shell of Fe atoms, and fluorescent X-rays are generated. On the other hand, if the energy is less than E2, the photoelectric effect does not occur in the K shell of Fe atoms, the transmittance of primary radiation does not decrease, and no fluorescent X-rays are emitted. The same applies to Co. When the energy is E1 or higher, a photoelectric effect occurs in the K shell of the Co atom, and fluorescent X-rays are generated.

Here, as described above, of the constituent elements of the subject, the element that adversely affects the detection of foreign matter (Fe) is Co of atomic number 27, and the energy E1 of the K absorption edge is 7.709 keV. Further, assuming that Fe (atomic number 26) is one of the elements constituting the foreign substance and the detection target element is Fe, the energy E2 of the K absorption edge of Fe is 7.112 keV. When an X-ray tube of a Ni target is selected as the radiation source, the energy peak EP of Kα rays, which are Ni characteristic X-rays, is 7.478 keV.
Accordingly, by setting (selecting) the radiation source so that E2 <EP <E1, the photoelectric effect of the detection target element (foreign matter) is effectively caused because E2 <EP, and the effect from the foreign matter (Fe) is obtained. In particular, Fe-Kα rays are generated and detection sensitivity increases. In addition, since EP <E1, no photoelectric effect occurs in Co, and therefore, the generation of Co-derived fluorescent X-rays that interfere with foreign Fe—Kα rays is suppressed, so that the Fe detection sensitivity increases. Further, by increasing the detection sensitivity, it is possible to quickly detect a foreign object while moving the subject.
From the above, since the measurement time is shorter and the detection sensitivity is improved as compared with the conventional X-ray fluorescence apparatus, it is possible to detect a foreign substance contained in a moving subject, which has been difficult in the past. On the other hand, in the case of a conventional fluorescent X-ray apparatus, the energy peak EP does not exist in the energy sandwiched between E1 and E2 in the primary radiation from the radiation source, so the effect of the present invention cannot be expected.

The energy (Ed) of the fluorescent X-rays of the foreign matter detected by the detector 12 is 6.404 keV Fe-Kα rays, and Ed <E2. The detector 12 may detect the entire energy range. However, if only a specific wavelength (energy) less than E2 is detected from the above-described relationship of Ed <E2, it is not necessary to detect an unnecessary energy range. Detection time is shortened.
Further, when the detector 12 detects a specific wavelength (energy) of less than E2, even when a wavelength dispersion type detector having a detection sensitivity higher than that of an energy dispersion type detector is generally used. Therefore, it is not necessary to map the energy to be detected, and the advantages of simplification and miniaturization of the detector can be enjoyed. Furthermore, Ed is smaller than E1 (for example, Ed is about 1.3 keV smaller than E1 in the above example), and the mass absorption coefficient of Co, which is the subject, is small at the energy that becomes Ed. Therefore, even the fluorescent X-rays generated from the foreign matter buried in the subject can be efficiently detected with a reduced rate of absorption by the subject.

FIG. 3 is a diagram showing a fluorescent X-ray spectrum of the fluorescent X-ray inspection apparatus of the present embodiment. As described above, the generation of Co fluorescent X-rays (Co-Kα) is suppressed, and is sufficiently separated from the fluorescent X-rays (Fe-Kα) of foreign matter (Fe) to be measured. Therefore, the background of the Fe—Kα ray is lowered and the detection sensitivity of Fe as a foreign matter is improved.
On the other hand, FIG. 4 is a diagram showing a fluorescent X-ray spectrum by a conventional fluorescent X-ray apparatus in which EP> E1. In the case of FIG. 4, a very strong Co—Kα line derived from the subject (Co) is generated, and the tail of the spectrum of this line has an adverse effect on the background of Fe—Kα, and the detection sensitivity of Fe decreases. In addition, when an energy dispersive detector is used, the detector (SDD) is saturated due to strong Co-Kα, and Fe-Kα is counted down or the resolution is reduced. As a result, even if the intensity of the radiation source is increased, it is difficult to sufficiently improve the detection sensitivity of Fe that is a foreign substance.

Next, with reference to FIG. 5, a detection example of foreign matter (stainless steel) mixed in the positive electrode active material sample (analyte) (lithium manganate (LiMn2O4)) will be described. FIG. 5 shows the relationship between the mass absorption coefficient and energy of one element (Mn) and foreign matter (Cr) constituting the object. When the foreign substance is stainless steel, the constituent elements of the foreign substance include Fe, Cr, and Ni, and the constituent element of the subject that adversely affects the detection of the foreign substance is Mn. Here, the atomic number of Mn is 25, and the energy E1 of the K absorption edge is 6.54 KeV. On the other hand, the atomic number of Fe is 26, the energy of K absorption edge is 7.112 keV, the atomic number of Cr is 24, the energy E2 of K absorption edge is 5.989 keV, the atomic number of Ni is 28, and the energy of K absorption edge is 8.333 keV. It is.
Among these, the energy of the K absorption edge of Fe and Ni is larger than the energy of the K absorption edge of Mn. Therefore, when the primary radiation having the energy to increase the intensity of the fluorescent X-rays of Fe and Ni is irradiated, the fluorescent X-ray intensity of Mn inevitably increases. And due to the strong Mn-Kα ray derived from Mn, Fe-Kα and Ni-Kα, which are fluorescent X-rays of Fe and Ni, are adversely affected. In other words, sufficient detection sensitivity cannot be obtained even when trying to detect stainless steel foreign matter with Fe or Ni.

For this reason, when Cr having an energy at the K absorption edge lower than that of Mn is set as a target element for detecting foreign matter, E2 <E1. When an X-ray tube of an Fe target is selected as the radiation source, the energy peak EP of Kα rays, which is the characteristic X-ray of Fe, is 6.404 keV. Therefore, the relationship of E2 <EP <E1 is satisfied, and the foreign matter (Cr) is detected without being affected by the subject (Mn) as in the case of the subject (Co) and the foreign matter (Fe) shown in FIG. Sensitivity can be improved. That is, since E2 <EP, the photoelectric effect of Cr is effectively caused, Cr—Kα rays are effectively generated, and the detection sensitivity is improved. In addition, since EP <E1, no photoelectric effect occurs in Mn, and therefore generation of fluorescent X-rays of Mn that interfere with Cr-Kα is suppressed.
The energy Ed of fluorescent X-rays (Cr-Kα rays) emitted from Cr is 5.415 keV, and Ed <E2. Further, Ed is smaller than E1 (for example, Ed is smaller than E1 by about 1.1 keV in the above example), and the mass absorption coefficient of Mn that is the subject is small at the energy that becomes Ed. Therefore, even the fluorescent X-rays generated from the foreign matter buried in the subject can be efficiently detected with a reduced rate of absorption by the subject.

In the above-described examples of FIGS. 2 and 5, the case where the atomic number of the subject and the foreign object is different from each other by 1 has been described. However, the present invention is applied even if the atomic number of the subject and the foreign object is two or more apart. it can.
For example, the specimen may detect Fe foreign matter with lithium nickelate (LiNiO ₂ or LiNi _0.8 Co _0.15 Al _0.05 O ₂ ). The element Ni constituting the object has an atomic number 2 larger than the foreign element Fe. In this case, an X-ray tube (radiation source) of the target material in which EP exists between E2 (7.112 keV) of Fe and E1 (8.333 keV) of Ni, that is, Ni target (EP = 7.478 keV) The X-ray tube may be selected.

Next, display processing of the radiation source 10 suitable for measurement by the CPU 22 will be described with reference to FIGS.
FIG. 6 shows the data structure of the element table 24 a stored in the storage unit 24. The element table 24a stores the K absorption edge and the Kα fluorescent X-ray energy for each element as one record. Each record is arranged in the order of the atomic number of the element, and each record is associated with the atomic number of the element.
FIG. 7 shows the data structure of the radiation source table 24 b stored in the storage unit 24. The radiation source table 24b stores the Kα-ray energy peak EP for each type of radiation source as one record.

FIG. 8 shows a flow of display processing of the radiation source 10 by the CPU 22.
First, when an operator (operator) operates the input unit 26 to input elements of a subject (for example, Co) and a foreign substance (for example, Fe), the CPU 22 acquires an input result (step S2). Next, the CPU 22 reads out the energy (E1, E2) of the K absorption edge of the subject (Co) and the foreign matter (Fe) from the table 24a. If the energy E1 at the K absorption edge of the subject is larger than the energy E2 at the K absorption edge of the foreign object, the CPU 22 determines “Yes” in step S4 and proceeds to step S6. On the other hand, if step S4 is “No”, the process returns to step S2 to prompt the operator to input again.
In step S2, it is indispensable to input an element to be detected among foreign substances, but it is not essential to input an element of the subject. The energy of the K absorption edge of the subject is higher than the energy of the K absorption end of the foreign substance. The operator may determine in advance whether or not it is larger. However, since the CPU 22 automatically performs the process of step S4, there is no mistake such as erroneous measurement even though the energy at the K absorption edge of the subject is smaller than the energy at the K absorption edge of the foreign object.

In step S6, the CPU 22 reads from the table 24b the type of radiation source having an EP value that satisfies E2 <EP <E1 based on E1 and E2 read in step S4.
Next, the CPU 22 displays on the monitor 28 the type (for example, “Ni target”) of the radiation source read in step S6 (step S8).
The radiation source displayed on the monitor 28 is attached (or replaced) to the fluorescent X-ray inspection apparatus manually by the operator or automatically by the apparatus.
In step S9, the CPU 22 reads the fluorescent X energy Ed of the foreign element to be detected from the table 24a. Based on the read Ed, the detection condition of the detector is set. Specifically, the detection condition of the detector is set, for example, as shown in FIG. 9 below so as to detect a predetermined range of energy region including Ed.

FIG. 9 is a block diagram showing the configuration of the detector 12. The detector 12 is an energy dispersive type, and includes a detection unit 121 such as a silicon drift type semiconductor detector (SDD), an amplifier 123 that shapes and amplifies the output of the detection unit 121, a pulse height analyzer 125, and a pulse height analyzer. And a memory 127 for temporarily storing 125 outputs. The pulse height analyzer 125 distributes the signal amplified by the amplifier 123 for each set voltage range (= energy of primary radiation), and counts the signals distributed to each set voltage range. The memory 127 stores the count value for each set voltage range in each of the memory areas 127a to 127c.
Here, the CPU 22 reads only the memory area corresponding to the energy within a predetermined range including the detection value Ed of the fluorescent X-rays of the foreign matter, and outputs it to the rate meter 14. Accordingly, since the memory areas 127a and 127b in which values corresponding to the energy other than the memory area corresponding to the detected value of the fluorescent X-ray of the foreign substance are stored are not read and output to the rate meter 14, the reading time from the memory 127, and The processing time in the rate meter 14 can be shortened and the measurement time can be shortened. In this way, since the measurement time is shortened, it is possible to detect foreign substances contained in the moving subject.

FIG. 10 is a block diagram of a detector when a wavelength dispersion type detector 13 is used as the detector used in the fluorescent X-ray inspection apparatus 1. The detector 13 is arranged along the optical path of the fluorescent X-rays diffracted by the spectral slit 131, the solar slit 133A arranged along the optical path of fluorescent X-rays emitted from the subject. A solar slit 133B, and a detection unit 135 that detects fluorescent X-rays diffracted by the spectral crystal 131 through the solar slit 133B.
The spectral crystal 131 is selected mainly depending on the wavelength region to be measured and the interplanar spacing of the crystal used. LiF the analysis of short heavy elements wavelengths ^{(2d = 4.03 × 10 -10 m} ), EDDT the analysis of the long light elements wavelengths ^{(2d = 8.8 × 10 -10 m} ) or ADP (2d = 10.65 × 10 ^{- 10} m) can be used for the spectroscopic crystal 131. As the detection unit 135, a proportional counter or a scintillation counter can be used.
In addition, by specifying the element of the foreign substance to be measured, the wavelength range detected by the detector (including Ed) can be limited, and qualitative analysis can be performed quickly using a wavelength dispersion type detector. Become. Therefore, so-called mapping is not essential, and the inspection time is shortened, so that foreign substances contained in the moving sample can be detected.

In the present embodiment, a signal (fluorescent X-ray count value) detected by the detector 12 (or 13) is input to the rate meter 14. The rate meter 14 outputs the count value to the personal computer 20 as a count number (count rate) per unit time.
As shown in FIG. 10, the CPU (signal processing means) 22 can determine that there is a foreign object when the count rate Sg exceeds a threshold value SH. As a result, it is possible to appropriately detect the foreign matter separately from the noise. In FIG. 10, the threshold value SH has two values, and when the count rate becomes smaller than the lower value threshold value SH and when the count rate becomes larger than the higher value threshold value SH, the count rate becomes the threshold value. It is determined that SH has been exceeded. The threshold value SH is set to about three times the standard deviation of noise.
If the CPU (signal processing means) 22 determines the presence of a foreign object when the count rate Sg exceeds the threshold value SH for a certain time or more, it is appropriate without being affected by noise. It becomes possible to detect foreign matter.

When the foreign object is buried in the subject 100, the primary radiation from the radiation source 10 and fluorescent X-rays emitted from the subject 100 (and the foreign matter 110 in the subject) are absorbed by the subject. It attenuates. Therefore, as shown in FIG. 11, it is preferable from the viewpoint of improving detection sensitivity to minimize the process (L ₁ + L ₂ ) through which the primary radiation and fluorescent X-ray pass through the subject. Then, the incident angle theta ₁ of the primary radiation into the subject 100, when equal to the exit angle theta ₂ of the fluorescent X-rays from the subject 100, found that it is possible to minimize the (L 1 _{+ L 2)} It was.
However, since the radiation source 10 and the detector 12 have sizes, θ ₁ and θ ₂ do not become 0 but take a predetermined value. Therefore, it is preferable from the viewpoint of improving detection sensitivity that the radiation source 10 is as close as possible to the subject 100 while θ ₁ = θ ₂ .

Next, a specific measurement example for a subject will be described.
In the actual lithium ion battery positive electrode structure (200 × 250 mm, positive electrode active material LiMn ₂ O ₄ ; thickness 70 μm, current collector Al; thickness 20 μm), the foreign matter is SUS powder on the positive electrode surface, and the Cr in the SUS The emitted fluorescent X-ray was detected. A wavelength dispersion type fluorescent X-ray inspection apparatus was used, an Fe tube having an output of 3 kW (50 kV) was used as the X-ray tube, and a proportional counter was used as the detector. The determination of Cr detection was made when a signal equivalent to 10 times the standard deviation of the background was detected.
As a result, the measurement time in the 200 × 250 mm region on the positive electrode can be detected in 1 second or less when the foreign matter is SUS particles of φ100 μm, about 2-3 seconds when the foreign matter is φ50 μm, and when the foreign matter is φ35 μm. The detection was possible in about 10 seconds, and it was confirmed that the detection was possible at a practical level for the moving positive electrode.

When an X-ray tube (sphere) is used as a radiation source, continuous X-rays are generated in addition to characteristic X-rays that can be used for the energy peak EP. While the predetermined component of the continuous X-ray contributes to the generation of fluorescent X-rays of the foreign matter, 1) it contributes to the generation of fluorescent X-rays of other constituent elements of the subject that adversely affect the measurement of the foreign matter, and 2) the subject It causes the problem that it is scattered and becomes the background component of the fluorescent X-ray of the element to be detected (foreign matter). Therefore, if a radioisotope that does not emit continuous X-rays is used as a radiation source, the above problems 1) and 2) can be solved and the foreign matter detection sensitivity can be improved.
As such an example, the element constituting the object is Mn (K absorption edge energy E1 is 6.540 keV), and one element constituting the foreign substance is Cr (K absorption edge energy E2 is 5.989 keV). In this case, when ¹⁸¹ W, which is a radioisotope, is used as the primary radiation, ¹⁸¹ Ta gamma rays (energy 6.24 keV) are emitted with the decay of ¹⁸¹ W EC (electron capture). This 6.24 keV γ ray can be applied to the peak EP where the energy of the primary radiation is between E1 and E2, and the effect of the present invention can be effectively obtained.
Similarly, when ⁵⁷ Co, which is a radioisotope, is used as the primary radiation, Fe Kα rays (energy 6.404 kev) are emitted with the decay of EC (electron capture) of ⁵⁷ Co. This K _α ray of Fe can be applied to the peak EP where the energy of the primary radiation is between E1 and E2, and the effect of the present invention can be obtained effectively.

  It goes without saying that the present invention is not limited to the above-described embodiment, but extends to various modifications and equivalents included in the spirit and scope of the present invention.

DESCRIPTION OF SYMBOLS 1 X-ray fluorescence analyzer 10 Radiation source 12, 13 Detector 14 Rate meter 22 Reading means, display means, signal processing means (CPU)
24 storage means 100 subject (sample)
110 Foreign matter

Claims (8)

A fluorescent X-ray inspection apparatus applied when a foreign object contained in a moving subject is detected and an atomic number of one element constituting the subject is larger than an atomic number of one element constituting the foreign object There,
A radiation source for irradiating the subject with primary radiation; and a detector for detecting fluorescent X-rays emitted from one element constituting the foreign matter by irradiation of the primary radiation,
When the energy at the K absorption edge of one element constituting the subject is E1, and the energy at the K absorption edge of one element constituting the foreign substance is E2, the primary radiation has an energy peak EP,
E2 <EP <E1
A fluorescent X-ray inspection apparatus. A rate meter that outputs a counting rate of fluorescent X-rays detected by the detector;
The fluorescent X-ray inspection apparatus according to claim 1, further comprising a signal processing unit that determines that a foreign substance is present when the count rate exceeds a threshold value. The fluorescent X-ray inspection apparatus according to claim 2, wherein the signal processing unit determines that a foreign substance is present when a time when the count rate exceeds the threshold is equal to or longer than a predetermined time. Storage means for storing energy of K absorption edges and Kα fluorescence X-rays of a plurality of elements including the foreign matter and the elements constituting the subject, and the energy peak EP of the primary radiation associated with the radiation source When,
When one element constituting the subject and one element constituting the foreign substance are designated, a reading means for reading out the radiation source satisfying the relationship of E2 <EP <E1 from the storage means;
2. The fluorescent X-ray inspection apparatus according to claim 1, further comprising display means for displaying the radiation source read by the reading means. The fluorescence according to any one of claims 1 to 4, wherein the element constituting the specimen is Co, and one element constituting the foreign substance is Fe, and the primary radiation includes a characteristic X-ray of Ni. X-ray inspection equipment. The element constituting the specimen is Mn, and one element constituting the foreign matter is Cr,
The fluorescent X-ray inspection apparatus according to claim 1, wherein the primary radiation includes Fe characteristic X-rays. The element constituting the specimen is Mn, and one element constituting the foreign matter is Cr,
The fluorescent X-ray inspection apparatus according to claim 1, wherein the radiation source uses ¹⁸¹ W or ⁵⁷ Co that is a radioisotope. A fluorescent X-ray inspection method applied when a foreign substance contained in a moving subject is detected and an atomic number of one element constituting the subject is larger than an atomic number of one element constituting the foreign substance There,
When the energy at the K absorption edge of one element constituting the subject is E1, and the energy at the K absorption edge of one element constituting the foreign substance is E2, the energy peak EP is present, and E2 <EP <E1. Irradiating the subject with certain primary radiation;
And a step of detecting fluorescent X-rays emitted from one element constituting the foreign substance by irradiation of the primary radiation.

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