JP2016125922A - X-ray analysis device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an energy dispersion type X-ray analysis device that correctly estimates deterioration of an X-ray detector, and allows a replacement time to be notified.SOLUTION: An X-ray analysis device comprises a detector lifetime estimation counting unit 6b that performs a wave height analysis of a detection output of a fluorescent X-ray by an X-ray detector 2, and counts the detection output for each wave height, separately from an analysis counting unit 6a. By the detector lifetime estimation counting unit 6b, a signal for each wave height is always counted and accumulated from a use start time of the X-ray detector 2. At a time when a result of the counting reaches a preliminarily set condition, notification means is configured to notify to the effect that a replacement time of the detector has come, and thereby a damage is estimated by using intensity of an X-ray, to which the X-ray detector 2 has been exposed since the use start time, for each energy as a parameter, which in turn allows a correct lifetime to be estimated.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an X-ray analyzer, and more particularly to an energy dispersive X-ray analyzer.

  In an X-ray analyzer, generally, fluorescent X-rays (characteristic X-rays) generated by irradiating a sample with excitation X-rays are detected, and energy (wavelength) and intensity (dose) of the fluorescent X-rays are obtained. . Since the fluorescent X-rays (characteristic X-rays) emitted from the sample have energy (wavelength) inherent to the element, the elements contained in the sample can be identified by obtaining the energy (wavelength) of the fluorescent X-rays. The concentration of the element can be known from the intensity (dose).

  The X-ray analyzer is classified into an energy dispersion type and a wavelength dispersion type depending on how to analyze the energy (wavelength) of fluorescent X-rays. In an energy dispersive X-ray analyzer, fluorescent X-rays emitted from a sample are directly detected by an X-ray detector such as a semiconductor detector, and the detected output wave height is correlated with the X-ray energy. Using this, the output signal of the X-ray detector is subjected to wavelength analysis and discriminated for each wave height, that is, for each energy, and the dose for each energy is obtained. On the other hand, in a wavelength dispersive X-ray analyzer, fluorescent X-rays emitted from a sample are dispersed for each wavelength using a spectroscopic crystal, and fluorescent X-rays having a specific wavelength are selected and detected by an X-ray detector. .

  Of the two types of X-ray analyzers described above, the energy dispersive type apparatus directly detects the fluorescent X-rays emitted from the sample without performing wavelength selection with an X-ray detector. Mechanical wavelength scanning for wavelength selection is not required as in the apparatus, and a large amount of wavelength information can be obtained at the same time. Therefore, the apparatus configuration is simple and the time required for acquiring the fluorescent X-ray spectrum is short. There is a feature (see, for example, Patent Document 1).

  By the way, Si (Li) semiconductor detectors and silicon drift detectors having excellent energy resolution are used as the X-ray detectors used in the energy dispersive X-ray tipping device. Deteriorated by X-ray exposure over time. If the X-ray detector deteriorates in the energy dispersive X-ray analyzer, it is natural that accurate measurement cannot be performed. Therefore, it is desirable to replace the X-ray detector before the deterioration proceeds to a certain extent. However, an X-ray analyzer having a function of predicting the deterioration of the X-ray detector and notifying or notifying the replacement time is currently known. It is not done.

  On the other hand, among other components in this type of analyzer, many proposals have already been made for members that deteriorate due to long-term use, such as X-ray tubes. Time is counted, and information related to the replacement time is reported by comparing the count value with a preset lifetime or guaranteed time (see, for example, Patent Document 2).

JP 2010-107261 A Japanese Patent Laid-Open No. 5-283192

  By the way, an X-ray detector (semiconductor detector) used in an energy dispersive X-ray analyzer can be easily considered when it is intended to have a function for notifying the replacement time before it deteriorates. This is the same function as the notification of the replacement time of the X-ray tube shown in Patent Document 2 and the like described above. That is, it is a function of accumulating the ON time of the X-ray detector and notifying that the replacement time has come when a certain time is reached. However, with such a method, it is impossible to correctly notify the replacement time of the X-ray detector.

  That is, the X-ray detector has a high possibility of deterioration when the intensity and energy of the X-ray to which the detector is exposed is high, and it is deteriorated by simply integrating the ON time of the X-ray detector. It cannot be a parameter that represents the degree of progression.

  The present invention has been made in view of such circumstances, and an object of the present invention is to accurately estimate the deterioration of the X-ray detector in the energy dispersive X-ray analyzer and notify the replacement time.

  In order to solve the above problems, an X-ray analyzer of the present invention includes an X-ray detector that detects fluorescent X-rays generated by irradiating a sample with excitation X-rays, and a wave height of an output signal of the X-ray detector. It has a wave height analyzing means for performing analysis and a counting means for counting the wave height analyzed signal for each wave height for a preset measurement time, and the element contained in the sample and its concentration are obtained from the counting result. In the X-ray analysis apparatus, a detector life prediction counting means is provided separately from the counting means, and the detector life prediction counting means outputs a signal whose wave height has been analyzed from the start of use of the X-ray detector. There is a discriminating means for constantly counting and accumulating for each wave height, and discriminating whether or not the counting result by the detector life prediction counting means has reached a preset condition. Discrimination by means Based on, upon reaching the above condition, characterized by that it comprises a notifying means for reporting purport of arrival replacement timing of the X-ray detector (claim 1).

  Here, in the present invention, the condition for arrival of the replacement time of the X-ray detector is that the count value of the signal for each wave height by the detector life prediction counting means is weighted and added as the wave height increases. It is possible to suitably employ a configuration (claim 2) in which the weighted addition value thus formed has reached a preset threshold value.

  Further, in the present invention, the condition for arrival of the replacement time of the X-ray detector is a height equal to or higher than a preset wave height among the count values of the signals for each wave height by the detector life prediction counting means. It is also possible to adopt a configuration (claim 3) in which the sum of the count values of the signals reaches a preset threshold value.

  In the present invention, the detector life prediction counting means is supplied with a signal analyzed by a dedicated wave height analyzing means provided separately from the wave height analyzing means. It is preferable that a signal obtained by shaping the signal from the X-ray detector based on a preset short signal shaping time constant is supplied (claim 4).

  The present invention counts the intensity and energy of X-rays to which the detector is exposed, which can be a parameter indicating the degree of progress of the deterioration of the X-ray detector, by analyzing the output of the detector for each wave height. The problem is solved by always counting using a counting means (counting means for predicting the detector life) different from the counting means for analysis that counts for the measurement time. It is what.

  That is, by analyzing the wave height of the output of the X-ray detector and counting each wave height, it is possible to know the intensity and energy of the X-rays to which the detector has been exposed, and the accumulation from the start of use of the X-ray detector. The result can be a parameter representing the progress of the deterioration of the X-ray detector. However, the counting means for analyzing the sample (the counting means that this type of analyzer originally has as a basic component) has a detector output wave height (X-ray energy) for a set measurement time. ), And even if the counting results of the counting means are added over a plurality of measurements, information on the X-rays to which the X-ray detector was exposed outside the measurement time is not included. That is, in this type of analyzer, a period for current adjustment is provided prior to measurement, and adjustment is performed while detecting fluorescent X-rays during that period. Therefore, X-rays to which the X-ray detector is exposed during this adjustment period are not included in the counting result by the counting means for analysis.

  Therefore, in the present invention, a counting means for predicting the detector life is provided separately from the counting means for analysis, and all of the detector life prediction counting means from the start of use of the X-ray detector. The output wave height analysis results are always counted for each wave height. Thereby, the information regarding all the X-rays to which the X-ray detector is exposed can be accumulated.

  Then, the counting result by the detector life prediction counting means is determined by the determining means that the preset condition has been reached, and by notifying that the X-ray detector is ready for replacement, It is possible to prompt the user to replace the X-ray detector before it deteriorates.

  As a condition for the arrival of the replacement time of the X-ray detector, as in the invention according to claim 2, the count value of the signal for each wave height by the detector life prediction counting means is set such that the higher the wave height, the higher the X-ray energy. The larger the value is, the weighted addition value obtained by weighting and adding reaches the threshold value or, as in the invention according to claim 3, by the detector life prediction counting means Among the count values of the signals for each wave height, the sum of the count values of signals having a height equal to or higher than the preset wave height can reach a preset threshold value, In either case, the arrival of the replacement time is determined on the condition that the amount of damage received by the X-ray detector has reached a certain limit.

  Furthermore, the output of the X-ray detector in this type of analyzer includes various noises and baseline fluctuations, and in order to remove these influences, the signal is appropriately shaped before the wave height analyzing means. The time for shaping is called a signal shaping time constant or peaking time, and the longer this time is, the more the SN improves. As a result, accurate wave height analysis becomes possible. The probability of occurrence of a so-called pile-up phenomenon occurs. In order not to perform wave height analysis on the piled-up signal as a regular signal, circuit means called a pile-up rejector is provided in front of the wave height analyzing means, and means for eliminating the piled-up signal is provided. . If the signal piled up in this way is excluded, the analysis result by the wave height analyzing means is a part of the X-rays incident on the X-ray detector missing, and this is counted by the detector life prediction counting means. However, the X-ray detector does not accurately represent the exposed X-rays.

  The invention according to claim 4 solves this problem. In the invention according to claim 4, apart from the wave height analyzing means for analysis (the wave height analyzing means which this type of analyzer originally has as a basic component), the detector life prediction count A dedicated wave height analyzing means is provided for the means, and for this, an input signal to the wave height analyzing means for analysis is set while increasing the peaking time in order to increase the SN and ensure the accuracy of analysis, The input signal to the wave height analyzing means provided exclusively for the detector life prediction counting means shortens the peaking time, and does not cause pileup even if the SN is somewhat worse, so that the detector life prediction counting means can be used. It becomes possible to derive the wave height analysis results for all the outputs from the X-ray detector. As a result, information on all X-rays incident on the X-ray detector is obtained, and by using this information as information for determining the replacement time of the X-ray detector, more accurate life prediction can be realized.

  According to the present invention, the intensity and energy of the X-rays to which the X-ray detector is exposed are accurately detected, the degree of progress of deterioration of the detector is grasped from the accumulated result, and the detector replacement timing is determined. Notification can be performed, and the occurrence of problems due to detector deterioration can be prevented in advance.

The block diagram which shows embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
The X-ray from the X-ray tube 1 is focused to a required size by a collimator or the like (not shown) and irradiated to the sample W as an excitation X-ray 11. The fluorescent X-rays 12 are emitted from the sample W by the irradiation of the excitation X-rays 11, and the fluorescent X-rays 12 are emitted by the X-ray detector 2 including a semiconductor detector such as a Si (Li) detector or a silicon drift detector. Detected.

  The output of the X-ray detector 2 is converted into a voltage signal by the preamplifier 3, amplified and signal shaped by the proportional amplification / signal shaping unit 4 a as in the conventional case, and then guided to the multichannel analyzer (MCA). . In the MCA, the wave height analysis unit 5a performs signal wave height analysis, and the counting unit 6a counts the signal for each wave height. This counting is performed for a preset measurement time, and the counting result of the signal for each wave height, that is, for each energy represents the spectrum of the fluorescent X-rays 12 emitted from the sample W. The X-ray spectrum information is sent to the data processing unit, and the elements contained in the sample W and their concentrations are obtained. The counting unit 6a transmits the counting result to the data processing unit as described above when the measurement time ends, and then resets the counting result to prepare for the next measurement.

  In the proportional amplification / signal shaping unit 4a, as described above, the signal shaping is performed by amplifying the input signal, but the time for signal shaping, that is, the peaking time (signal shaping time constant) is variable. Is set between 2 and 20 μs. The longer the peaking time, the better the SN, and the wave height analyzer 5a in the next stage can accurately analyze the wave height of the signal. On the other hand, a pile-up phenomenon occurs when the frequency of signal generation is high. The proportional amplification / signal shaping unit 4a is provided with a function for preventing the piled-up signal from being sent to the wave height analyzing unit 5a, that is, a pile-up rejector, and considering that the piled-up signal is not counted by the counting unit 6a. Has been.

  The feature of this embodiment is that another circuit configuration equivalent to the circuit configuration from the proportional amplification / signal shaping unit 4a to the counting unit 6a is used for predicting the detector lifetime.

  In other words, the output from the X-ray detector 2 that has passed through the preamplifier 3 is also input to the proportional amplification / signal shaping unit 4b of another system in addition to the above-described proportional amplification / signal shaping unit 4a, so that amplification and signal shaping are performed. Is done. However, the peaking time in the proportional amplification / signal shaping unit 4b is set to a short time in advance. Thereby, although the SN of the signal is somewhat deteriorated, the pile-up phenomenon does not occur, and the proportional amplification / signal shaping unit 4b receives all the signals from the X-ray detector 2 inputted through the preamplifier 3 as the wave height of the next stage. The data is sent to the analysis unit 5b.

  The wave height analysis unit 5b is the same as the wave height analysis unit 5a for analysis described above, performs the wave height analysis of the input signal, and supplies it to the counting unit 6b. The counting unit 6b counts the signal for each wave height that has been subjected to wave height analysis in the same manner as the above-described analyzing counting unit 6a. However, the counting unit 6b completes one measurement. Instead of resetting the count content every time, the signal count from the start of use of the X-ray detector 2 is continued. In addition, the detector life prediction counting unit 6b does not count the signal only during the measurement time, but also counts the output from the X-ray detector 2 generated during the adjustment period preceding the measuring device.

  Therefore, the count content of the detector life prediction counter 6b is the result of counting all the signals output from the detector 2 for each wave height from the start of use of the X-ray detector 2, in other words. For example, the X-ray detector 2 represents the cumulative value of the intensity for each energy of all the X-rays exposed from the start of use.

  The count content of the detector life prediction counting unit 6b is sent to the weighting addition unit 7 as needed, and the weighting addition unit 7 adds the count content with a higher weight as the wave height increases. Therefore, the weighted addition value is a value obtained by adding the weights of the intensities of all the X-rays to which the X-ray detector 2 has been exposed from the start of use, with higher energy, This is a parameter representing the damage caused by the X-rays that the detector 2 has received so far.

  Then, the weighted addition value by the weighting addition unit 7 is compared with a threshold value set in advance in the determination unit 8, and the determination unit 8 detects the X-ray when the weighted addition value exceeds the threshold value. A notification output indicating that the replacement time of the detector 2 has arrived is generated. By this notification output, for example, a display to that effect is displayed or an alarm sound is generated to notify the operator to that effect.

  According to the above-described embodiment of the present invention, it is possible to prevent an error in the analysis result due to deterioration of the X-ray detector 2 in advance. In addition, since the life prediction is based on the intensity of each X-ray energy that the X-ray detector 2 has been exposed from the start of use, it is possible to accurately and accurately predict the life.

  Here, in the above embodiment, the example in which the arrival of the replacement time of the X-ray detector is notified when the weighted addition value reaches the threshold value is shown, but a plurality of threshold values are set. Alternatively, preliminary notification may be performed before the replacement time arrives.

  Moreover, in the above embodiment, although the example which set it as the parameter for lifetime prediction by weighting and adding the count content of the counting part 6b was shown, this invention is not limited to this, For example, a counting part Among the count contents of 6b, a parameter obtained by simply adding X-ray count values exceeding the preset energy can be used.

  Furthermore, in the above embodiment, a dedicated proportional amplification / signal shaping unit 4b for life prediction is provided separately from the proportional amplification / signal shaping unit 4a for analysis, and the signal shaped by this is similarly used. Although an example was shown in which the wave height was analyzed by the dedicated wave height analysis unit 5b and used for counting by the counting unit 6b, the signal passed through the proportional amplification / signal shaping unit 4a for analysis and the wave height analysis unit 5a was used for detector life prediction. A configuration in which the counting unit 6b always counts and accumulates may be employed. In this configuration, when a pileup of a signal occurs, the pileup rejector eliminates the signal, and the count content of the counting unit 6b does not necessarily accurately match the X-ray to which the X-ray detector 2 has been exposed. Although not shown, considering that the occurrence of the pile-up phenomenon is not so large, or the probability that the pile-up phenomenon occurs is not so different in normal use of the apparatus, the determination unit 8 is expected to take this into consideration. By making the threshold value small, it is possible to perform an almost accurate life prediction.

DESCRIPTION OF SYMBOLS 1 X-ray tube 2 X-ray detector 3 Preamplifier 4a, 4b Proportional amplification and signal shaping part 5a, 5b Wave height analysis part 6a, 6b Counting part 7 Weighting addition part 8 Judgment part 11 Excitation X-ray 12 Fluorescence X-ray W sample

Claims (4)

An X-ray detector for detecting fluorescent X-rays generated by irradiating the sample with X-rays for excitation, a pulse height analyzing means for analyzing the pulse height of the output signal of the X-ray detector, and the signal subjected to the pulse height analysis in advance In an X-ray analyzer having a counting means for counting for each wave height for a set measurement time, and obtaining an element contained in the sample and its concentration from the counting result,
In addition to the counting means, a detector life prediction counting means is provided. The detector life prediction counting means always counts the signal subjected to wave height analysis for each wave height from the start of use of the X-ray detector. And having a discriminating unit for discriminating whether or not the counting result by the detector life prediction counting unit has reached a preset condition, and based on the discrimination result by the discriminating unit An X-ray analysis apparatus comprising an informing means for informing that it is time to replace the X-ray detector when the above condition is reached.   The X-ray detector replacement time arrival condition is a weighted addition value obtained by adding the count value of the signal for each wave height by the detector life prediction counting means with a higher weight as the wave height is higher, The X-ray analysis apparatus according to claim 1, wherein a threshold value set in advance is reached.   The condition for arrival of the replacement time of the X-ray detector is the sum of the count values of signals having a height not less than a preset wave height among the count values of signals at each wave height by the detector life prediction counting means. The X-ray analysis apparatus according to claim 1, wherein a threshold value set in advance is reached.   The detector life prediction counting means is supplied with a signal analyzed by a dedicated wave height analyzing means provided separately from the wave height analyzing means. The dedicated wave height analyzing means is supplied with the signal from the X-ray detector. The X-ray according to any one of claims 1 to 3, wherein a signal obtained by shaping a signal based on a preset short signal shaping time constant is supplied. Analysis equipment.

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