JPH07104292B2 - X-ray analyzer - Google Patents

Description

TECHNICAL FIELD The present invention relates to an X-ray analyzer, and more particularly to a mechanism for automatically setting a peak value of a peak analyzer.

(B) Prior Art and Problems Thereof A wave height analyzer is used in an X-ray analyzer such as an X-ray diffractometer or a fluorescent X-ray analyzer. This wave height analyzer utilizes the fact that the magnitude of the detection pulse output from an X-ray detector such as a scintillation counter is proportional to the energy of the X-ray. As shown in FIG. If unnecessary interfering X-rays (indicated by diagonal lines in the figure) other than X-rays that are Through which unnecessary X-rays are energetically separated and removed.

Therefore, when the wave height analyzer is used, it is necessary to set the upper limit value and the lower limit value of the wave height value in advance according to the characteristics of the X-ray to be analyzed. Conventionally, the applied high voltage of the X-ray detector is set to a constant value, the gain of the proportional amplifier is changed to find the gain that gives the maximum count value of the detection pulse, and then the peak analyzer The channel width is narrowed and the peak value is temporally scanned from the low level to the high level to obtain the differential curve, and the upper limit value and the lower limit value of the wave height analyzer are determined from the differential curve.

Conventionally, all of these operations have been performed manually, so that the operation of setting the peak value is complicated.

Further, the peak value is determined by (gain of X-ray detector) × (gain of proportional amplifier). Therefore, when the same peak value is obtained, when the gain of the proportional amplifier is set to a small value, a relative X value is obtained.
It is necessary to set the gain of the line detector large. However, it is not preferable to increase the gain of the X-ray detector, that is, the applied high voltage, because the peak shift amount of the peak value becomes large and the peak value is erroneously selected. Conventionally, as described above, the gain of the proportional amplifier is adjusted rather than the gain of the high voltage applied to the X-ray detector, so that the gain of the X-ray detector may inevitably be set high. However, in that case, an increase in the peak shift amount was unavoidable.

In view of such circumstances, the present invention enables to automatically determine the high voltage applied to the X-ray detector and the upper limit value and the lower limit value of the peak value of the peak analyzer, and the peak value at that time. The purpose is to reduce the peak shift amount.

(C) Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides a pulse height for selecting an X-ray detector and a detection pulse having a constant peak value output from the X-ray detector. An X-ray analysis apparatus including an analyzer, a counter that counts the detection pulses that have passed through the wave height analyzer, and a high-voltage generator that generates a high voltage to be applied to the X-ray detector is provided with the following configuration. It has a feature.

That is, in the present invention, the first
As shown in the figure, an applied high voltage control means a for outputting a control signal for stepwise changing the applied high voltage outputted from the high voltage generator, and the applied high voltage control means a change the applied high voltage of the X-ray detector. Peak detection means b for detecting the maximum value of the X-ray count value with respect to the applied high voltage based on the count value of the detection pulse obtained each time, and the applied high voltage in response to the maximum value detection signal of the peak detection means b. And a signal output means c for outputting a fixed signal.

(D) Operation The operation of the configuration of the present invention is as follows.

With the gain of the proportional amplifier held at a constant level near the maximum range, a control signal is output from the applied high voltage control means a to change the applied high voltage applied from the high voltage generator to the X-ray detector stepwise. In this case, since the gain of the proportional amplifier is set near the maximum range, X
The gain of the line detector, that is, the applied high voltage, can be adjusted within a small range, and thus the peak shift amount of the peak value can be suppressed to a small value.

Then, the maximum value of the count value of the detection pulse counted by the counter in accordance with the change of the applied high voltage is the peak detecting means b.
Detected in.

When the maximum value of the count value is obtained, the signal output means c fixes the X-ray detector to the applied high voltage that gives the maximum value. Then, the differential curve measurement mode is entered, and the upper limit value and the lower limit value of the wave height analyzer are determined based on the differential curve measured in this mode.

(E) Embodiment FIG. 2 is a block diagram showing the configuration of the X-ray analysis apparatus according to the embodiment of the present invention. In the figure, reference numeral 1 is an X-ray analyzer, and for example, an X-ray diffractometer, a fluorescent X-ray analyzer or the like is applied. Reference numeral 2 is a main body including an X-ray power controller, an X-ray tube, and the like, and 4 is an X-ray detector including a scintillation counter, a proportional counter, and the like. Further, 6 is a high voltage generator that generates a high voltage applied to a dynode of the X-ray detector 4, 8 is a proportional amplifier that amplifies the X-ray detection pulse output from the X-ray detector 4, and 10 is X-ray detection. A wave height analyzer for selecting only the detection pulses having a constant wave height output from the device 4, and a counter 12 for counting the detection pulses passing through the wave height analyzer 10. Reference numeral 14 is a control device (CPU) for sequence-controlling the operations of the main body 2, the high-voltage generator 6, and the wave height analyzer 10 according to a certain processing program. The control device 14 includes each means a shown in FIG. In addition to b and c, it has a built-in memory. Note that 16a to 16d are control devices.
This is a D / A converter that analogizes the control signal from 14.

Next, in the X-ray analysis apparatus 1 of this embodiment, the procedure and operation for setting the peak value of the peak analyzer 10 will be described with reference to the flowchart shown in FIG.

First, initial values for setting parameters such as flag setting and step width of applied high voltage are set (step n1). that time,
The gain of the proportional amplifier 8 is fixed in advance to a constant level near the maximum range (a noise component is about 0.1 V at the output of the wave height analyzer 10 as a guide).

Next, the voltage at the center of the dynamic range of the pulse height analyzer 10
Set Vc (step 2). Subsequently, the upper limit value and the lower limit value of the wave height analyzer are set to values of ± 50% of the center voltage Vc (step 3). Further, the control device 14 gives a control signal to the high-voltage generator 6 to set the high-voltage V applied to the X-ray detector 4 to the minimum value.
Set to Vmin (step 4). In this state, the detection pulse from the X-ray detector 4 is counted by the counter 12 (step 5). Then, the count value I is compared with the count value J obtained last time (step 6), but since there is no previous count value and J = 0 at first, the process proceeds to step 7, and the X-ray detector 4 After the high voltage V applied to is increased by a constant step width ΔV, the count value I obtained this time is set as the previous count value J (step 8), and then the process returns to step 5 and is increased by ΔV. The detected pulses are counted under the applied high voltage. Next, in step 6, the value I currently counted and the previous count value J are compared. If the X-ray intensity tends to increase, then I> J, so the process proceeds to step 7 again. In this way
While increasing the applied high voltage V stepwise, the detection pulse output from the X-ray detector 4 is counted each time. This is so that the count value of the detection pulse becomes maximum within the range of the fixed upper limit value and lower limit value of the wave height analyzer 10.
This means adjusting the gain of the line detector 4. Also,
In this case, since the gain of the proportional amplifier 8 is set near the maximum range, the gain of the X-ray detector 4, that is, the applied high voltage, can be adjusted in a relatively small range, and therefore, the peak shift amount of the peak value. Can be kept small.

In this way, when the high voltage applied to the X-ray detector 4 is gradually increased, the count value becomes maximum at a certain high voltage applied, and thereafter the count value decreases conversely, as shown in FIG. Therefore, when the count value detected by the counter 12 exceeds the maximum value, the current count value I becomes smaller than the previous count value J in step 6 (that is, I ≦ j). The high voltage applied to No. 4 is fixed to the applied high voltage Vfix which gives the maximum count value (step 9).

From step n3 to step 9, when setting the optimum applied high voltage for the X-ray detector 4, the upper and lower limits of the wave height analyzer 10 are set to a value of ± 50% of the center voltage Vc and the applied high voltage is set. Is roughly determined, the next step is to finely determine the optimum applied high voltage to improve the accuracy. This includes the controller 14
Thus, the upper limit value and the lower limit value of the wave height analyzer 10 are set narrowly to, for example, ± 20% of the center voltage Vc (step 1
1) The step width for increasing the applied high voltage is also made small (step 12), and the initial high voltage applied to the X-ray detector 4 is set to a value smaller by a constant value E than the voltage value Vfix giving the maximum count value. Yes (step 13). After setting the flag G to "2" (step 14), the process returns to step 5. Then, steps 5 to 8 are repeated to obtain the applied high voltage that gives the maximum count value, and the X-ray detector 4
The applied high voltage of is fixed to this optimum value (step 9).

In the next step 10, G ≧ 2, so that the process proceeds to step 15. In step 15, after setting the channel width W of the wave height analyzer 10 to 1% of the dynamic range (step
15) Then, the crest value is set to the low voltage V side (step 16), and in that state, the detection panel is counted by the counter 12 (step 17). Next, in step 18, it is determined whether or not the peak value has been scanned up to the maximum range voltage value Vmax, and if it has not reached the maximum value, the count value is stored in the memory (step 19), and then the peak value is reached. Is increased by a constant step width ΔVo (step 20), the process returns to step 17, and the detection pulse is counted under the peak value increased by ΔVo. In this manner, the detection pulse output from the X-ray detector 4 is counted each time the peak value is increased stepwise, and the count value is stored in the memory. These steps 17 to 20 mean that the peak value is scanned from the low voltage side to the high voltage side while maintaining the constant channel width W to obtain the differential curve. In this way, when the differential curve is obtained, a value of ± 5% is obtained around the peak value that gives the maximum value of the differential curve (step 2
1) Set each value as the upper limit and lower limit (step 2)
2).

In this way, the peak value of the peak analyzer 10 is automatically set.

(F) Effect As described above, according to the present invention, the upper and lower limits of the high voltage applied to the X-ray detector and the peak value of the peak analyzer can be automatically determined. The complicated operation of setting the peak value is eliminated. Furthermore, an excellent effect is exhibited such that the peak shift amount of the peak value at the time of adjusting the peak value can be reduced.

[Brief description of drawings]

FIG. 1 is a functional block diagram corresponding to the claims of the present invention, FIG. 2 is a block diagram showing a configuration of an X-ray analysis apparatus of the present invention, and FIG. 3 is a peak value setting of a wave height analyzer of the apparatus. FIG. 4 is a flow chart for explaining the operation, FIG. 4 is a characteristic diagram showing a change in count value with a change in applied high voltage of the X-ray detector,
FIG. 5 is an explanatory diagram of the wave height analyzing operation of the wave height analyzer. a ... Applied high voltage control means, b ... Peak detection means, c ...
... signal output means, 1 ... X-ray analyzer, 4 ... X-ray detector, 10 ... wave height analyzer, 12 ... counter, 14 ... control device.

Claims (1)

[Claims] 1. An X-ray detector, a pulse height analyzer for selecting a detection pulse having a constant peak value output from the X-ray detector, and a counter for counting the detection pulses passing through the pulse height analyzer. An X-ray analysis apparatus comprising: a high voltage generator that generates a high voltage to be applied to an X-ray detector; and an applied high voltage control means that outputs a control signal for stepwise changing the applied high voltage output from the high voltage generator. A peak detecting means for detecting the maximum value of the count value of the detection pulse with respect to the applied high voltage based on the count value of the detection pulse obtained each time the applied high voltage of the X-ray detector is changed by the applied high voltage control means; An X-ray analysis device comprising: a signal output unit that outputs a signal for fixing the applied high voltage in response to a maximum value detection signal of the detection unit.