JP5197069B2 - Radiation position detector - Google Patents

Description

  The present invention relates to a radiation position detection apparatus.

  In an accelerator facility or the like, a radiation detector is used to monitor radiation leakage inside the facility. For example, in an accelerator facility, particles such as protons and electrons may get out of orbit. In this case, the radiation detector is used to detect a beam that is out of orbit, that is, lost, and plays an important role such as providing a guideline for operations such as adjustment. In general, when a lost beam is detected, an ionization chamber is used as a radiation detector because the radiation from the loss beam has a relatively large dose.

However, although the ionization chamber can detect the presence or absence of radiation, it is difficult to detect the position information of the radiation. In view of this, a radiation position detection apparatus capable of detecting radiation position information has been proposed (see, for example, Non-Patent Document 1).
"Radiation Measurement Handbook (Third Edition)", Nikkan Kogyo Shimbun, page 215

  The radiation position detection apparatus includes a radiation position detector having an electrode to which a high voltage is applied, a preamplifier connected to both ends of the electrode, and a capacitor provided between the electrode and the preamplifier, which cuts the high voltage. . The radiation position detector converts incident radiation into an electrical signal and outputs the signal to both ends of the electrode. The magnitude (charge amount) of the signal output to both ends of the electrode depends on the radiation generation position (incident position).

  Signals output from both ends of the electrodes are output to the preamplifier via a capacitor and integrated. When the signal is integrated by the preamplifier, charges are accumulated in the capacitor of the preamplifier, but the same amount of charge is accumulated in the capacitor that cuts off the high voltage. The signal integrated by the preamplifier is then subjected to waveform shaping and A / D conversion. The radiation position detection apparatus acquires position information based on the intensity ratio of signals output from both ends of the electrodes and A / D converted.

  By the way, the electric charge accumulated in the capacitor that cuts the high voltage is charged and discharged through the electrode. Since the radiation position detection apparatus is affected by the above-described influence, distortion that causes overshoot or undershoot occurs in the waveform of the waveform-shaped signal. For this reason, in the radiation position detection apparatus, although the position resolution is excellent when the incident radiation is small, the position resolution is degraded when the incident radiation is large (at a high count rate).

More specifically, when the amount of incident radiation is large, the interval between pulses of the waveform-shaped signal is shortened, so that a pulse is generated during overshoot or undershoot. Then, the peak value of the generated pulse becomes lower or higher than the actual value. When the waveform-shaped pulse is A / D converted, the peak value of the pulse becomes lower or higher than the original value. As a result, the position calculation result by the radiation position detection apparatus fluctuates, and the position resolution decreases.
The present invention has been made in view of the above points, and an object of the present invention is to provide a radiation position detection apparatus excellent in position resolution.

In order to solve the above problems, a radiation position detection apparatus according to an aspect of the present invention includes:
A radiation position detector that has a resistive electrode and outputs a first signal to one end of the electrode and a second signal to the other end of the electrode according to a radiation incident position;
A first preamplifier connected to one end of the electrode;
A first capacitor connected between one end of the electrode and a first preamplifier;
A second preamplifier connected to the other end of the electrode;
A second capacitor connected between the other end of the electrode and a second preamplifier;
Connected to the first preamplifier and the second preamplifier, the first signal is transmitted from the first preamplifier and the second signal is transmitted from the second preamplifier, and the strengths of the first signal and the second signal are transmitted. A measurement unit for measuring the incident position of radiation from the ratio,
The time constant of the first preamplifier is less than the time constant due to the resistance component of the electrode and the first capacitor,
The time constant of the second preamplifier is less than the time constant of the resistance component of the electrode and the second capacitor.

  According to the present invention, it is possible to provide a radiation position detection device having excellent position resolution.

Hereinafter, a radiation position detection apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the radiation position detection device, which is a radiation position detection type detection device, is a radiation position detector 1, a first capacitor 4a, a second capacitor 4b, and a charge integration type preamplifier. First preamplifier 5a and second preamplifier 5b, blocking resistor 6, high-voltage power supply unit 7, first waveform shaping amplifier 10a, second waveform shaping amplifier 10b, first A / D converter 11a, and second A / D A D converter 11b and an arithmetic circuit 12 as a measurement unit are provided.

  The radiation position detector 1 includes an outer case 2, a resistive electrode 3 accommodated in the outer case, and other electrodes (not shown) provided in the outer case and provided around the electrode 3. have.

  The other electrode is a cathode and is formed in a cylindrical shape. Here, the other electrodes are at 0 V (volt) potential. The electrode 3 is an anode and is housed inside another electrode. The electrode 3 is provided so as to extend along the central axis of the other electrode. The shape of the electrode 3 is a wire shape. Here, a high voltage of + several kV is applied to the electrode 3. The resistance value of the electrode 3 is several kΩ. The electrode 3 and the other electrodes are insulated.

  The outer case 2 is formed in a cylindrical shape. The outer case 2 is provided to accommodate the electrode 3 and other electrodes in a state in which the outer case 2 is kept insulated from the electrode 3. In this embodiment, both side surfaces of the outer case 2 are closed, and the inside of the outer case 2 is airtight.

  Inside the outer case 2 including the inside of the other electrode, a mixed gas based on a rare gas is sealed as an ionized gas. Here, a gas that is not polymerized even in a high radiation field is selected.

Here, the radiation position detection method by the radiation position detector 1 will be described.
When the radiation r is incident on the radiation position detector 1, the radiation ionizes the gas inside the outer case 2. This generates charges due to ions and electrons. At the incident position (generation position) of the radiation r, electrons are collected by the electrode 3 which is an anode. The radiation position detector 1 outputs a first signal to one end A of the electrode 3 and a second signal to the other end B of the electrode 3 according to the incident position of the radiation r. That is, each of the first signal and the second signal has a charge amount corresponding to the incident position of the radiation r.

Here, the length from one end A to the other end B of the electrode 3 is L, and the length from one end A of the electrode 3 to the radiation incident position is x. Then, the charge amount Q _A of the first signal output to one end A of the electrode 3 and the charge amount Q _B of the second signal output to the other end B of the electrode 3 are expressed by the following equations.

Q _A = (Q _A + Q _B ) × (L−x) / L
Q _B = (Q _A + Q _B ) × x / L
As can be seen from the above equation, when the incident position of the radiation r is intermediate between the one end A and the other end B (x = L / 2), the charge amount Q _A of the first signal and the charge amount Q _{B of} the second signal. Are the same. Further, when the incident position of the radiation r is close to the first end A from the other end B (x <L / 2) , the charge amount Q _A of the first signal is greater than the charge amount Q _B of the second signal. On the contrary, when the incident position of the radiation r is closer to the other end B than the one end A (x> L / 2), the charge amount Q _B of the second signal is larger than the charge amount Q _A of the first signal.

  The first preamplifier 5 a is connected to one end A of the electrode 3. The first capacitor 4a is connected between one end A of the electrode 3 and the first preamplifier 5a. More specifically, the first capacitor 4 a is connected to one end A of the electrode 3 through the connector of the radiation position detector 1. The second preamplifier 5 b is connected to the other end B of the electrode 3. The second capacitor 4b is connected between the other end B of the electrode 3 and the second preamplifier 5b. More specifically, the second capacitor 4 b is connected to the other end B of the electrode 3 via the connector of the radiation position detector 1.

  The arithmetic circuit 12 is connected to the first preamplifier 5a and the second preamplifier 5b. The first waveform shaping amplifier 10 a is connected between the first preamplifier 5 a and the arithmetic circuit 12. The first A / D converter 11 a is connected between the first waveform shaping amplifier 10 a and the arithmetic circuit 12. The second waveform shaping amplifier 10 b is connected between the second preamplifier 5 b and the arithmetic circuit 12. The second A / D converter 11 b is connected between the second waveform shaping amplifier 10 b and the arithmetic circuit 12.

  The first preamplifier 5a includes an operational amplifier 13a, an integrating capacitor 9a that is a capacitor, and a discharge resistor 8a that is a resistor. The operational amplifier 13a is disposed between the first capacitor 4a and the first waveform shaping amplifier 10a. The integrating capacitor 9a is connected in parallel with the operational amplifier 13a. The discharge resistor 8a is connected in parallel with the operational amplifier 13a and the integrating capacitor 9a. The time constant of the first preamplifier 5a is τp1. The time constant τp1 is set (determined) by the integrating capacitor 9a and the discharge resistor 8a.

  The first signal output from the radiation position detector 1 is input to the first preamplifier 5a. Thereby, the first preamplifier 5a collects the charge of the first signal. The charges collected by the first preamplifier 5a are accumulated in the integrating capacitor 9a.

  The second preamplifier 5b includes an operational amplifier 13b, an integrating capacitor 9b that is a capacitor, and a discharge resistor 8b that is a resistor. The operational amplifier 13b is disposed between the second capacitor 4b and the second waveform shaping amplifier 10b. The integrating capacitor 9b is connected in parallel to the operational amplifier 13b. The discharge resistor 8b is connected in parallel to the operational amplifier 13b and the integrating capacitor 9b. The time constant of the second preamplifier 5b is τp2. The time constant τp2 is set (determined) by the integrating capacitor 9b and the discharge resistor 8b.

  In this embodiment, the time constant τp1 of the first preamplifier 5a and the time constant τp2 of the second preamplifier 5b are the same. Therefore, hereinafter, the time constant of the first preamplifier 5a and the time constant of the second preamplifier 5b are set to τp.

  The second signal output from the radiation position detector 1 is input to the second preamplifier 5b. Thereby, the second preamplifier 5b collects the charge of the second signal. The charges collected by the second preamplifier 5b are accumulated in the integrating capacitor 9b.

  The high voltage power supply unit 7 is connected to one end A of the electrode 3 through the blocking resistor 6 on the one end A side of the electrode 3 from the first capacitor 4a. Another high-voltage power supply unit 7 is connected to the other end B of the electrode 3 via the blocking resistor 6 on the other end B side of the electrode 3 from the second capacitor 4b. The high voltage power supply unit 7 applies a high voltage to the electrode 3 through the blocking resistor 6. The blocking resistor 6 is provided so that the charge generated by the radiation position detector 1 does not flow to the high voltage power supply unit 7 side.

  Since the high voltage is applied to the electrode 3, the first preamplifier 5a is connected to one end A of the electrode 3 via the first capacitor 4a for high voltage cut. Similarly, the second preamplifier 5b is also connected to the other end B of the electrode 3 through the second capacitor 4b for high voltage cut.

  Here, the time constant set (determined) by the resistance component of the electrode 3 and the first capacitor 4a is τd1, and the time constant set (determined) by the resistance component of the electrode 3 and the second capacitor 4b is τd2. In this embodiment, the time constant τd1 and the time constant τd2 are the same. Therefore, hereinafter, the resistance component of the electrode 3 and the time constant due to the first capacitor 4a and the resistance component of the electrode 3 and the time constant due to the second capacitor 4b are referred to as τd.

  The first waveform shaping amplifier 10a shapes the first signal input from the first preamplifier 5a, and makes the waveform of the first signal a waveform with a short pulse width. Thereby, even when the number of radiation incident on the radiation position detector 1 is large, it is possible to prevent the plurality of pulses of the first signal from overlapping.

  Similarly to the first waveform shaping amplifier 10a, the second waveform shaping amplifier 10b also shapes the second signal input from the second preamplifier 5b, and makes the waveform of the second signal a waveform with a short pulse width. It is. Thereby, even if it is a case where the number of the radiation which injects into the radiation position detector 1 is many, the overlap of the several pulse of a 2nd signal can be prevented.

  The first A / D converter 11a performs A / D conversion (digitization) on the first signal, whereby the peak value of the pulse of the first signal can be obtained. The second A / D converter 11b performs A / D conversion (digitization) on the second signal, whereby the peak value of the pulse of the second signal can be obtained.

The arithmetic circuit 12 receives the first signal from the first preamplifier 5a and the second signal from the second preamplifier 5b. More specifically, the first signal digitally converted from the first A / D converter 11a is transmitted to the arithmetic circuit 12, and the second signal digitally converted is transmitted from the second A / D converter 11b. . The arithmetic circuit 12 calculates (measures) the incident position of the radiation r from the intensity ratio of the input first signal and second signal. For this reason, the arithmetic circuit 12 acquires information on the charge amount Q _A of the first signal and information on the charge amount Q _B of the second signal, performs an operation for obtaining the length x from the acquired information, and enters the radiation r Find the position.

  Next, the radiation position detection apparatus of Examples 1 and 2 and Comparative Examples 1 and 2 of this embodiment and a radiation position detection method using this radiation position detection apparatus will be described.

(Comparative Example 1)
As shown in FIG. 1, the radiation position detection apparatus of Comparative Example 1 is formed as described above. In Comparative Example 1, the time constant τp is twice the time constant τd (τd = 0.5 × τp).

Next, a radiation position detection method using the radiation position detection apparatus will be described with reference to FIGS. 1, 2, 3, 4, and 5.
First, when the radiation r is incident on the radiation position detector 1, it reacts with the gas inside the outer case 2 to generate electric charges. The generated charges are collected by the electrode 3 to which a high voltage is applied. As a result, a signal having a rectangular waveform is generated from the electrode 3 overlapping the radiation incident position (FIG. 2A). The charge amount (crest value) of this signal is Q _A + Q _B.

This signal is output as a first signal to one end A of the electrode 3 and is output as a second signal to the other end B of the electrode 3 (FIGS. 2B to 2D). Charge amount of the first signal is a Q _A, the charge amount of the second signal is Q _B.

The first signal output from the radiation position detector 1 is input to the first preamplifier 5a. The amount of charge accumulated in the integrating capacitor 9a is Q _A. Here, since the radiation position detector 1 and the first preamplifier 5a are connected via the first capacitor 4a, the charge of the first signal is accumulated not only in the integrating capacitor 9a but also in the first capacitor 4a. The amount of charge accumulated in the first capacitor 4a is Q _A.

The second signal output from the radiation position detector 1 is input to the second preamplifier 5b. The amount of charge accumulated in the integrating capacitor 9b is Q _B. Here, since the radiation position detector 1 and the second preamplifier 5b are connected via the second capacitor 4b, the charge of the second signal is accumulated not only in the integrating capacitor 9b but also in the second capacitor 4b. The amount of charge accumulated in the second capacitor 4b is Q _B.
Then, when the charge amount Q _A of the first capacitor 4a, the charge amount Q _B of the second capacitor 4b are different, the first capacitor 4a and the second capacitor 4b is charged and discharged through the resistance of the electrode 3, Thereby, the charge amount of the first capacitor 4a and the charge amount of the second capacitor 4b become the same.

In the case of x <1/2 × L, Q _B <Q _A. Then, the first capacitor 4a is discharged and the second capacitor 4b is charged. More specifically, half of the difference between the charge amount Q _A and a charge amount Q _B is raised to the second signal. For this reason, the amount of charge of the second signal changes from Q _B to Q _B + (Q _A −Q _B ) / 2 (FIG. 2B). Then, the second capacitor 4b is charged as much as the second signal is raised.

In the case of x = 1/2 × L, Q _B = Q _A. In this case, there is no charge transfer between the first capacitor 4a and the second capacitor 4b. Therefore, the charge amount of the second signal does not change from _{Q B} (FIG. 2 (c)).

In the case of x> 1/2 × L, Q _B > Q _A. Then, the second capacitor 4b is discharged and the first capacitor 4a is charged. More specifically, half of the difference between the charge amount Q _B and the charge amount Q _A is reduced from the second signal. Therefore, the charge amount of the second signal changes from Q _B to Q _B − (Q _B −Q _A ) / 2 (FIG. 2D). Then, the second capacitor 4b is discharged as much as the second signal is reduced in volume.

From the above, the amount of charge accumulated in the integrating capacitor 9a is determined by the amount of charge Q _A indicated by the rectangular pulse generated by the radiation position detector 1 and the time constant generated by charging / discharging of the second capacitor 4b. It is the sum of the amount of charge.

Here, the second signal output from the radiation position detector 1 has been described, but the same applies to the first signal output from the radiation position detector 1. In this case, the charge amount Q _B may be read as the charge amount Q _A, and the case of x <1/2 × L and the case of x> 1/2 × L may be replaced.

Therefore, when x <1/2 × L, the charge amount of the first signal (charge amount accumulated in the integrating capacitor 9a) Q _A output from the first preamplifier 5a attenuates with a time constant τp (FIG. Instead of 2 (e) L1), in fact, in addition to the amount attenuated by the time constant τp, the amount of charge charged in the second capacitor 4b is attenuated earlier (FIG. 2 (e) L2).

When x = 1/2 × L, since the first capacitor 4a and the second capacitor 4b are not charged / discharged, the charge amount of the first signal output from the first preamplifier 5a (the charge amount accumulated in the integrating capacitor 9a) Q _A decays with a time constant τp (FIG. 2 (f)).

In the case of x> 1/2 × L, the charge is accumulated in the integrating capacitor 9a due to the discharge by the second capacitor 4b. Therefore, the charge amount of the first signal output from the first preamplifier 5a (accumulated in the integrating capacitor 9a). The charge amount Q _A does not decay with the time constant τp (FIG. 2 (g) L1), but actually becomes slower than decay with the time constant τp (FIG. 2 (g) L2).

  As described above, the radiation position detector 1 and the first preamplifier 5a are connected via the first capacitor 4a. For this reason, the decay time constant of the output of the first preamplifier 5a is not constant, but changes according to the incident position of the radiation.

Although the first signal output from the first preamplifier 5a has been described here, the same applies to the second signal output from the second preamplifier 5b. In this case, the charge amount _{Q A} read as a charge amount _{Q B,} sufficient to exchange in the case of x <case 1/2 × L and x> 1/2 × L. Since the radiation position detector 1 and the second preamplifier 5b are also connected via the second capacitor 4b, the attenuation time constant of the output of the second preamplifier 5b is not constant and changes according to the incident position of the radiation.

  The first signal output from the first preamplifier 5a has a time constant (usually several μs) shorter than the decay time constant (usually several hundred μs) of the first preamplifier 5a, and is composed of a differentiation circuit and an integration circuit. Waveform shaping is performed by the first waveform shaping amplifier 10a. At this time, the pole zero adjustment is performed so that distortion such as overshoot or undershoot does not occur in the waveform-shaped first signal pulse.

  When x = 1/2 × L, since the attenuation time constant of the first preamplifier 5a is constant, no distortion occurs in the first signal output from the first waveform shaping amplifier 10a (FIG. 3B). For this reason, even when the number of radiation incident on the radiation position detector 1 is large, overlapping of the plurality of pulses of the first signal can be prevented.

  However, in the case of x <1/2 × L, the attenuation time constant of the first preamplifier 5a is not constant, and the attenuation of the first signal output from the first preamplifier 5a becomes early, and the overshoot occurs in the pulse of the first signal. (FIG. 3A). For this reason, when the number of radiation incident on the radiation position detector 1 is large, the next incoming pulse overlaps the overshoot generated in the pulse, and the peak value of the pulse becomes lower than the original value (FIG. 4). . When the first signal pulse is A / D converted by the first A / D converter 11a, the peak value of the first signal pulse becomes lower than the original value. As a result, the calculation result of the incident position of the radiation r by the calculation circuit 12 varies, and the position resolution decreases.

  Similarly, when x> 1/2 × L, the attenuation time constant of the first preamplifier 5a is not constant, the attenuation of the first signal output from the first preamplifier 5a is delayed, and the pulse of the first signal is underlined. A chute occurs (FIG. 3 (c)). For this reason, when the number of radiation incident on the radiation position detector 1 is large, the next incoming pulse overlaps the undershoot generated in the pulse, and the peak value of the pulse becomes higher than the original value. When the first signal pulse is A / D converted by the first A / D converter 11a, the peak value of the first signal pulse becomes higher than the original value. As a result, the calculation result of the incident position of the radiation r by the calculation circuit 12 varies, and the position resolution decreases.

  FIG. 5 is a diagram showing the first signals shown in (e) to (g) of FIG. As shown in FIG. 5, it can be seen that a large variation occurs in the degree of attenuation of the first signal due to the difference in the incident position of the radiation r. That is, the position resolution is reduced due to a large variation in the decay time constant of the first preamplifier 5a (second preamplifier 5b).

(Comparative Example 2)
As shown in FIG. 1, the radiation position detection device of Comparative Example 2 is formed as described above, similarly to the radiation position detection device of Comparative Example 1. In Comparative Example 2, the time constant τp and the time constant τd are the same (τd = τp).

  The radiation position detection method using the radiation position detection apparatus is the same as that in the first comparative example. As shown in FIG. 6, it can be seen that when the incident position of the radiation r is different, the degree of attenuation of the first signal varies. That is, variation in the attenuation time constant of the first preamplifier 5a (second preamplifier 5b) causes a decrease in position resolution.

Example 1
As shown in FIG. 1, the radiation position detection device of Example 1 is formed as described above, like the radiation position detection device of Comparative Example 1 and the like. In the first embodiment, the time constant τp is less than the time constant τd. More specifically, the time constant τp is ½ times the time constant τd (τd = 2 × τp).

  The radiation position detection method using the radiation position detection apparatus is the same as that in the first comparative example. However, in Example 1, since τd = 2 × τp, variation in the degree of attenuation of the first signal is suppressed even when the incident position of the radiation r is different as shown in FIG. I understand. That is, variation in the attenuation time constant of the first preamplifier 5a (second preamplifier 5b) is suppressed. Distortion such as overshoot and undershoot that may occur in the pulse of the first signal waveform-shaped by the first waveform shaping amplifier 10a is suppressed. Needless to say, distortion that may occur in the waveform-shaped second signal pulse is also suppressed. For this reason, the fall of position resolution can be suppressed.

(Example 2)
As shown in FIG. 1, the radiation position detection device of Example 2 is formed as described above, like the radiation position detection device of Comparative Example 1 and the like. In the second embodiment, the time constant τp is less than the time constant τd. More specifically, the time constant τp is 1/10 times the time constant τd (τd = 10 × τp).

  The radiation position detection method using the radiation position detection apparatus is the same as that in the first comparative example. However, in Example 2, since τd = 10 × τp, as shown in FIG. 8, it can be seen that the degree of attenuation of the first signal is almost the same even if the incident position of the radiation r is different. . That is, the attenuation time constant of the first preamplifier 5a (second preamplifier 5b) is almost the same. Distortion such as overshoot and undershoot that may occur in the pulse of the first signal waveform-shaped by the first waveform shaping amplifier 10a is further suppressed. Needless to say, distortion that may occur in the waveform-shaped second signal pulse is further suppressed. For this reason, the fall of position resolution can be suppressed further.

  According to the radiation position detection apparatus configured as described above, the time constant τp of the first preamplifier 5a is less than the time constant τd of the resistance component of the electrode 3 and the first capacitor 4a, and the time constant of the second preamplifier 5b. τp is less than the time constant τd due to the resistance component of the electrode 3 and the second capacitor 4b. Thereby, it can be considered that the radiation has entered the center side of the electrode 3, and the influence of charging and discharging by the first capacitor 4a and the second capacitor 4b can be reduced. Even when the radiation is incident on one end A or the other end b of the electrode 3, the influence of charging / discharging can be reduced as in the case where the radiation is incident on the center side of the electrode 3.

  For this reason, even if the incident position of the radiation r is different, the attenuation time constants of the first preamplifier 5a and the second preamplifier 5b can be made substantially constant. Then, distortion that may occur in the pulses of the first signal and the second signal that have undergone waveform shaping is suppressed. As a result, when the number of radiation incident on the radiation position detector 1 is large, it is possible to suppress the overlap between the pulse and the next incoming pulse, so that the change in the peak value of the pulse can be suppressed. Can be obtained. As a result, the calculation result of the incident position of the radiation r by the calculation circuit 12 is stable, so that a good position resolution can be obtained.

The effects described above are that the time constant τp of the first preamplifier 5a is less than or equal to 1/2 of the resistance component of the electrode 3 and the time constant τd of the first capacitor 4a, and the time constant τp of the second preamplifier 5b is the resistance component of the electrode 3. The time constant τd of the first preamplifier 5a is larger than the time constant τd by the second capacitor 4b, and the time constant τp of the first preamplifier 5a is 1/10 or less of the resistance component of the electrode 3 and the time constant τd by the first capacitor 4a. If the time constant τp of the second preamplifier 5b is 1/10 or less of the resistance component of the electrode 3 and the time constant τd of the second capacitor 4b, it is even greater.
From the above, it is possible to obtain a radiation position detection device having excellent position resolution.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  The radiation position detection apparatus further includes a first resistor connected between one end A of the electrode 3 and the first preamplifier 5a, and a second resistor connected between the other end B of the electrode 3 and the second preamplifier 5b. May be. For example, the first resistor may be connected between one end A of the electrode 3 and the first capacitor 4a, and the second resistor may be connected between the other end B of the electrode 3 and the second capacitor 4b. Alternatively, the first resistor may be connected between the first capacitor 4a and the first preamplifier 5a, and the second resistor may be connected between the second capacitor 4b and the second preamplifier 5b. In the above case, the time constant τp of the first preamplifier 5a is less than the time constant τd of the resistance component of the electrode 3, the first resistor and the first capacitor 4a, and the time constant τp of the second preamplifier 5b is the resistance of the electrode 3 The effects described above can be obtained as long as it is less than the time constant τd of the component, the second resistor, and the second capacitor 4b.

  As long as the time constant τp1 is less than the time constant τd1 and the time constant τp2 is less than the time constant τd2, the time constant τp1 of the first preamplifier and the time constant τp2 of the second preamplifier may be different from each other.

  If the time constant τp1 is less than the time constant τd1 and the time constant τp2 is less than the time constant τd2, the capacity of the first capacitor 4a and the capacity of the second capacitor 4b are different from each other, the resistance value of the discharge resistor 8a and the discharge The resistance value of the resistor 8b may be different from each other, or the capacitance of the integrating capacitor 9a and the capacitance of the integrating capacitor 9b may be different from each other.

1 is a schematic configuration diagram showing a radiation position detection apparatus according to an embodiment of the present invention. It is a timing chart which shows the signal which generate | occur | produced in the said radiation position detection apparatus, Especially in the radiation position detection apparatus of the comparative example 1 of the said embodiment, (a) The signal which generate | occur | produced in the radiation position detection apparatus, (b) x < Second signal output from electrode when 1/2 × L, (c) Second signal output from electrode when x = 1/2 × L, (d) Output from electrode when x> 1/2 × L (E) a first signal output from the first preamplifier when x <1/2 × L, (f) a first signal output from the first preamplifier when x = 1/2 × L, ( g) A diagram showing a first signal output from the first preamplifier when x> 1/2 × L. FIG. 3 is a timing chart showing a signal generated by the radiation position detection apparatus following FIG. 2, and in particular, in the radiation position detection apparatus of the comparative example 1 of the embodiment, (a) when x <1/2 × L 1st signal output from 1 waveform shaping amplifier, (b) 1st signal output from 1st waveform shaping amplifier when x = 1/2 × L, (c) 1st waveform when x> 1/2 × L The figure which shows the 1st signal output from the shaping amplifier. The figure which shows the 1st signal output from 1st waveform shaping amplifier when the pulse shown to Fig.3 (a) generate | occur | produces continuously. The figure which shows the 1st signal output from 1st preamplifier in the radiation position detection apparatus of the comparative example 1 of the said embodiment. The figure which shows the 1st signal output from 1st preamplifier in the radiation position detection apparatus of the comparative example 2 of the said embodiment. The figure which shows the 1st signal output from a 1st preamplifier in the radiation position detection apparatus of Example 1 of the said embodiment. The figure which shows the 1st signal output from a 1st preamplifier in the radiation position detection apparatus of Example 2 of the said embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Radiation position detector, 3 ... Electrode, 4a ... 1st capacitor, 4b ... 2nd capacitor, 5a ... 1st preamplifier, 5b ... 2nd preamplifier, 8a, 8b ... Discharge resistance, 9a, 9b ... Integration capacitor, 10a ... 1st waveform shaping amplifier, 10b ... 2nd waveform shaping amplifier, 11a ... 1D converter, 11b ... 2D converter, 12 ... arithmetic circuit, 13a, 13b ... operational amplifier, r ... radiation, A ... one end, B ... The other end, x, L ... length, Q _A , Q _B ... charge amount, τd, τd1, τd2, τp, τp1, τp2 ... time constant.

Claims (6)

A radiation position detector that has a resistive electrode and outputs a first signal to one end of the electrode and a second signal to the other end of the electrode according to a radiation incident position;
A first preamplifier connected to one end of the electrode;
A first capacitor connected between one end of the electrode and a first preamplifier;
A second preamplifier connected to the other end of the electrode;
A second capacitor connected between the other end of the electrode and a second preamplifier;
Connected to the first preamplifier and the second preamplifier, the first signal is transmitted from the first preamplifier and the second signal is transmitted from the second preamplifier, and the strengths of the first signal and the second signal are transmitted. A measurement unit for measuring the incident position of radiation from the ratio,
The time constant of the first preamplifier is less than the time constant due to the resistance component of the electrode and the first capacitor,
The radiation position detecting device, wherein a time constant of the second preamplifier is less than a time constant of the resistance component of the electrode and the second capacitor. The time constant of the first preamplifier is ½ or less of the time constant due to the resistance component of the electrode and the first capacitor,
The radiation position detection apparatus according to claim 1, wherein a time constant of the second preamplifier is equal to or less than ½ of a time constant of the resistance component of the electrode and the second capacitor.   The radiation position detection apparatus according to claim 1, wherein a time constant of the first preamplifier and a time constant of the second preamplifier are the same. A first A / D converter connected between the first preamplifier and the measurement unit for digitally converting the first signal;
The radiation position detection apparatus according to claim 1, further comprising: a second A / D converter connected between the second preamplifier and the measurement unit and digitally converting the second signal. The first preamplifier includes an operational amplifier connected between the first capacitor and the measurement unit, a capacitor connected in parallel to the operational amplifier, and a resistor connected in parallel to the operational amplifier and the capacitor. Set to the time constant of the first preamplifier,
The second preamplifier includes an operational amplifier connected between the second capacitor and the measurement unit, a capacitor connected in parallel to the operational amplifier, and a resistor connected in parallel to the operational amplifier and the capacitor. The radiation position detection apparatus according to claim 1, wherein the radiation position detection apparatus is set to a time constant of the second preamplifier. A radiation position detector that has a resistive electrode and outputs a first signal to one end of the electrode and a second signal to the other end of the electrode according to a radiation incident position;
A first preamplifier connected to one end of the electrode;
A first capacitor connected between one end of the electrode and a first preamplifier;
A first resistor connected between said first capacitor及 beauty first preamplifier,
A second preamplifier connected to the other end of the electrode;
A second capacitor connected between the other end of the electrode and a second preamplifier;
A second resistor connected between said second capacitor及 beauty second preamplifier,
Connected to the first preamplifier and the second preamplifier, the first signal is transmitted from the first preamplifier and the second signal is transmitted from the second preamplifier, and the strengths of the first signal and the second signal are transmitted. A measurement unit for measuring the incident position of radiation from the ratio,
The time constant of the first preamplifier is less than the time constant of the resistance component of the electrode, the first resistor, and the first capacitor,
The time constant of the second preamplifier, the resistance component of the electrode, the second resistor and Ru der less than the constant Radiation position detecting device when by the second capacitor.

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