MCP detector and analysis device

Abstract

This MCP detector (1) is provided with: an MCP (3) having an input surface (3a) into which electrons (e1) are input; multiplication units (11A, 11B) that multiply electrons generated in accordance with the input of the electrons (e1); an output surface (3b) that outputs the electrons (e2) multiplied by the multiplication units (11A, 11B); a planar dynode (5) which is separated from the output surface (3b), is arranged substantially parallel to the output surface (3b), and multiplies the electrons (e2) output from the output surface (3b); a positive electrode (8) that is disposed between the output surface (3b) and the dynode (5) so as to be separated from the output surface (3b) and the dynode (5), and that collects the electrons (e3) multiplied by the dynode (5); and a dynode (7) that is disposed between the anode (8) and the dynode (5) so as to be separated from the anode (8) and the dynode (5), further multiplies the electrons (e3) multiplied by the dynode (5), and passes toward the anode (8).

Description

Technical Field

[0001] One aspect of the embodiments relates to an MCP detector and an analysis device. Background Art

[0002] Analytical devices such as MS (mass spectrometry) devices equipped with microchannel plates (MCPs) require improved output linearity. To improve output linearity, researchers have studied reducing the resistance of the plates. However, improvements in output linearity achieved through lower resistance have reached their limits.

[0003] Research has long been underway on triode structures that combine an anode and dynodes on a microchannel plate. As a conventional charged particle detector with a triode structure, for example, the electron multiplier device described in Patent Document 1 below is known. This electron multiplier device includes an MCP, dynodes arranged parallel to the output surface of the MCP, and a lattice-shaped anode.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 57-196466 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] In conventional electron multiplying devices such as those described above, the detection performance of a detector equipped with an MCP reaches its limit due to the inherent output linearity of the MCP. Therefore, there is a demand for improving the detection performance of a detector equipped with an MCP.

[0009] Therefore, one aspect of the embodiment has been made in view of such a problem, and the problem is to provide an MCP detector and an analysis device capable of improving the detection performance of a detector equipped with an MCP.

[0010] Means used to solve problems

[0011] The MCP detector involved in the first aspect of the embodiment comprises: a microchannel plate, which has: an input surface to which charged particles are input; a multiplying portion that multiplies electrons generated according to the input of the charged particles; and an output surface that outputs the electrons multiplied by the multiplying portion; a planar first dynode that is separated from the output surface and arranged approximately parallel to the output surface and multiplies the electrons output from the output surface; an anode that is arranged between the output surface and the first dynode, separated from the output surface and the first dynode, and collects the electrons multiplied by the first dynode; and a second dynode that is arranged between the anode and the first dynode, separated from the anode and the first dynode, and further multiplies the electrons multiplied by the first dynode and passes them toward the anode.

[0012] Alternatively, an analysis device according to the second aspect of the embodiment includes the above-mentioned MCP detector.

[0013] According to the first aspect or the second aspect, based on the charged particles input to the input surface of the microchannel plate (hereinafter also referred to as "MCP"), the electrons output from the output surface of the MCP that have passed through the anode and the second dynode are multiplied by the first dynode, and the multiplied electrons are multiplied again by the second dynode and pass toward the anode. Then, the electrons multiplied by the second dynode are captured by the anode. Thus, the output signal based on the obtained electrons at the anode can reflect the number of electrons whose output electrons of the MCP are repeatedly multiplied by the two dynodes. As a result, the overall output linearity of the MCP detector can be improved, and the detection performance of the MCP detector or an analysis device equipped with it can be improved.

[0014] Effects of the Invention

[0015] According to any aspect of the present disclosure, the detection performance of a detector equipped with an MCP can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a cross-sectional view showing the structure of the MCP detector 1 according to the embodiment.

[0017] Figure 2 It is a plan view showing the specific structure of the anode 8 .

[0018] Figure 3 It is a cross-sectional view showing the support structure of the anode 8 and the dynode 7 .

[0019] Figure 4 It is a cross-sectional view showing a multiplication state of secondary electrons in one channel of the multiplication sections 11A and 11B of the MCP 3 , the potential of which is set by the control section 9 .

[0020] Figure 5 1 is a block diagram showing the configuration of the signal processing unit 9 a of the control unit 9 .

[0021] Figure 6 This is a graph showing the measurement results of the gain at each electrode when the potential of the linear dynode 7 is changed in the MCP detector 1 .

[0022] Figure 7 This is a graph showing the measurement results of the gain in the MCP detector 1 .

[0023] Figure 8 This is a graph showing the measurement results of the gain in the MCP detector 1 .

[0024] Figure 9 It is a plan view showing the structure of a modified example of the anode 8 .

[0025] Figure 10 This is a diagram for explaining a method of calculating an input position of the signal processing unit 9 a based on a pulse signal output from the anode 8 .

[0026] Figure 11 It is a diagram showing an example of display of an image generated by the signal processing unit 9a.

[0027] Figure 12 It is a diagram showing an example of display of an image generated by the signal processing unit 9a. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same elements or elements having the same functions are denoted by the same reference numerals, and repeated descriptions are omitted.

[0029] Figure 1 : is a cross-sectional view showing the structure of the MCP detector 1 according to the embodiment. Figure 1 In the diagram, the circuit section is shown as a block. The MCP detector 1 is a device that detects input charged particles. The charged particles to be detected may include electrons or ions. In this embodiment, electrons are exemplified as the detection targets of the MCP detector 1.

[0030] like Figure 1 As shown, the MCP detector 1 includes an MCP 3, a dynode (first dynode) 5, a dynode (second dynode) 7, an anode 8, and a control unit 9. The MCP 3, dynode 5, dynode 7, and anode 8 are generally planar and arranged substantially parallel to one another. The following describes the various components of the MCP detector 1.

[0031] The MCP 3 is composed of an input surface 3a into which electrons are input; a pair of multiplying sections 11A and 11B that multiply the secondary electrons generated by the input electrons (secondary electron multiplication) while maintaining the two-dimensional position of the electrons relative to the input surface 3a; and an output surface 3b that outputs the electrons multiplied by the multiplying sections 11A and 11B. Each of the multiplying sections 11A and 11B is a secondary electron multiplying section having multiple independent microchannel structures. Multiple microchannel structures are arranged two-dimensionally in the multiplying sections 11A and 11B.

[0032] Each channel in multiplying sections 11A and 11B has an inner diameter of approximately 10 μm and is tilted approximately 10 degrees relative to the normal direction of input surface 3a (the direction in which electrons enter). The tilt directions of the channels are reversed in multiplying sections 11A and 11B. In multiplying sections 11A and 11B, the output surface 3b side is set to a higher potential than the input surface 3a side. Secondary electrons generated by electrons reaching input surface 3a are multiplied by multiplying sections 11A and 11B, and these multiplied secondary electrons are output from output surface 3b.

[0033] The dynode 5 is an electrode that multiplies the electrons output from the MCP3. The dynode 5 is a roughly flat electrode separated from the output surface 3b of the MCP3 and arranged roughly parallel to the output surface 3b. That is, the dynode 5 has a support member 5a made of a metal material such as flat stainless steel (SUS) and a secondary electron emission film 5b formed on the surface of the MCP3 close to the support member 5a. The secondary electron emission film 5b is composed of a secondary electron emitting material such as Al2O3, BeO, LiF, MgF2, MgO, CsBr, NaCl or crystalline diamond. In addition, the support member 5a can also be a member formed by stacking a conductive layer on a flat member made of an insulating material. In this case, the secondary electron emission film 5b is formed on the conductive layer of the support member 5a.

[0034] Anode 8 is an electrode disposed between the output surface 3b of MCP 3 and dynode 5, separated from MCP 3 and dynode 5, and collects (captures) electrons multiplied by secondary electron emission film 5b of dynode 5 and emitted toward output surface 3b. Anode 8 is disposed closer to dynode 5 than the center between output surface 3b and dynode 5. Anode 8 comprises a linear anode 8a extending in a first direction X along a plane substantially parallel to output surface 3b.

[0035] The wire anode 8a is a thin metal wire (metal wire) 13 made of copper, nickel, chromium, SUS, or the like, with an anti-oxidation coating (gold plating) 15 applied. For example, the wire width of the wire anode 8a is in the range of 50 μm to 200 μm. The wire anode 8a extends in the X direction at multiple locations spaced at predetermined intervals (e.g., intervals of 200 μm to 1 mm) in a second direction Y perpendicular to the first direction X, and is electrically connected as a whole.

[0036] Figure 2 1 is a plan view showing the specific structure of the line anode 8a. The line anode 8a is as follows Figure 2 As shown in part (a) of FIG. 1 , a structure in which metal thin wires are arranged in a zigzag pattern in a manner that bridges a pair of opposite sides of a frame-shaped insulating support member (not shown) can be adopted. In addition, the wire anode 8a can also be as shown in FIG. Figure 2 As shown in part (b), a metal thin wire is wound around a pair of opposite sides of a frame-shaped insulating support member (not shown) in a non-overlapping manner. In addition, the wire anode 8a may also have two layers. Figure 2 The structure shown in part (a) or (b) is formed so that the two layers of metal fine wires extend in the first direction X and the second direction Y orthogonal to each other in a state where the two layers of metal fine wires are electrically insulated from each other.

[0037] In addition, if Figure 2 As shown in part (c), the wire anode 8a may also be a structure in which two thin metal wires are arranged in parallel on a flat insulating support member (not shown) by being folded back multiple times at a certain period and electrically connected via triangular connection pads.

[0038] Alternatively, the line anode 8a may be Figure 2 As shown in part (d) of FIG. 1 , a plurality of linear thin metal wires are arranged at predetermined intervals. These plurality of thin metal wires may also be formed as two layers electrically connected to each other by a zigzag metal pattern. In this case, the two layers of thin metal wires are also formed to be electrically insulated from each other via an insulating member (not shown) and to extend in a first direction X and a second direction Y that are orthogonal to each other.

[0039] Both ends of the wire anode 8a having the above structure are electrically connected to the control unit 9. When the wire anode 8a has a two-layer structure, both ends of the metal thin wires of each layer are electrically connected to the control unit 9 independently.

[0040] The dynode 7 is an electrode that is arranged between the dynode 5 and the anode 8, separated from the dynode 5 and the anode 8 in a direction perpendicular to the output surface 3b, so that the electrons multiplied by the dynode 5 and heading toward the anode 8 are further multiplied and pass toward the anode 8. The dynode 7 is composed of a metal wire 23 extending in a second direction Y along a plane roughly parallel to the output surface 3b, and a secondary electron emission film 25 formed in a manner covering the entire metal wire 23. The metal wire 23 is made of a metal material in the same manner as the supporting member 5a of the dynode 5. The secondary electron emission film 25 is composed of a secondary electron emission material in the same manner as the secondary electron emission film 5b of the dynode 5. The metal wire 23 constituting the dynode 7 extends along the Y direction at a plurality of positions separated by a specified interval (for example, an interval of 200 μm or more and 1 mm or less) in the first direction X, and is electrically connected as a whole. The dynode 7 can be, for example, Figure 2 The structure shown in parts (a) and (b) of .

[0041] Here, the distance D2 between the dynode 7 and the dynode 5 is set to be greater than the distance D1 between the dynode 7 and the anode 8. In addition, the anode 8 is arranged near the dynode 5 as a whole, compared with the virtual plane 50 corresponding to the position halfway between the output surface 3b and the secondary electron emission film 5b of the dynode 5 and the position halfway between the secondary electron emission films 5b of the dynode 5.

[0042] Reference Figure 3 , the support structure of the anode 8 and the dynode 7 will be described. Figure 3 This is a cross-sectional view showing the support structure of anode 8 and dynode 7. Dynode 7 includes a support member 53 made of an insulating material, which supports dynode 7, and anode 8 includes a support member 55 made of an insulating material, which also supports anode 8. When viewing dynode 5 from output surface 3b, these support members 53 and 55 are positioned further outward from the area where secondary electron emission film 5b is provided on the surface of dynode 5 near MCP 3. Support member 53 and support member 55 may also be a common member.

[0043] The control unit 9 is electrically connected to the input surface 3a and output surface 3b of the MCP 3, the dynodes 5 and 7, and is a circuit that sets the potential of each and processes the pulse signal output from the anode 8. The control unit 9 includes a built-in signal processing unit 9a, which processes the pulse signal output from the anode 8 and performs detection processing related to the electrons input to the input surface 3a of the MCP 3.

[0044] Specifically, the control unit 9 applies voltages to the input surface 3a, output surface 3b, dynode 5, dynode 7, and anode 8 such that the potential of the output surface 3b is higher than the potential of the input surface 3a, the potential of the dynodes 5 and dynode 7 is higher than the potential of the output surface 3b, the potential of the anode 8 is higher than the potential of the dynode 7, and the potential of the dynode 7 is higher than the potential of the dynode 5. In other words, the control unit 9 sets the respective potentials such that the potentials increase in the order of input surface 3a, output surface 3b, dynode 5, dynode 7, and anode 8. For example, the control unit 9 sets the potential of the input surface 3a to 0V, the potential of the output surface 3b to +1920V, the potential of the dynode 5 to +2112V, the potential of the anode 8 to +2400V, and the potential of the dynode 7 to a potential higher than +2112V but lower than +2400V.

[0045] Figure 4 This is a cross-sectional view showing the multiplication state of secondary electrons in one channel of the multiplication section 11A, 11B of the MCP 3, the potential of which is set by the control section 9. An electrode 19 is provided at the end of the channel 17 on the input surface 3a side of the multiplication section 11A, 11B, and an electrode 21 is provided at the end of the channel 17 on the output surface 3b side of the multiplication section 11A, 11B. The electrode 21 of each channel 17 of the multiplication section 11A is electrically connected to the electrode 19 of each channel 17 of the multiplication section 11B. The control section 9 supplies a voltage between the electrode 19 of the multiplication section 11A and the electrode 21 of the multiplication section 11B to lower the potential of the electrode 19. As a result, a voltage V is applied between the two ends of the channel 17 of each multiplication section 11A, 11B. D , a strip current I is generated on the inner wall of the channel 17 from the end on the output surface 3b side toward the end on the input surface 3a side. S When an electron e1 is input from the end of the channel 17 on the input surface 3a side in this state, the electron e1 collides with the inner wall of the channel 17, thereby being multiplied. The secondary electrons e2 generated by repeated electron multiplication on the inner wall of the channel 17 are output from the end of the channel 17 on the output surface 3b side. The output electrons of the multiplication units 11A and 11B are taken out by the strip current I S Therefore, the output of MCP3 is linearly banded current I S Therefore, in order to improve the output linearity of MCP3 itself, it is necessary to reduce the resistance value of the inner wall of channel 17. In addition, output linearity refers to the upper limit of the number of output electrons per unit time that can output the number of input electrons and the number of output electrons while maintaining a linear relationship.

[0046] The signal processing unit 9a of the control unit 9 processes the pulse signal output from the end of the metal fine wire 13 of the anode 8 based on the electrons collected by the anode 8, and performs detection processing for the electron beam input to the input surface 3a of the MP3. Specifically, the signal processing unit 9a processes the pulse signal output within a predetermined time, obtains the pulse height distribution (PHD) characteristics, and thereby counts the number of input electrons.

[0047] Figure 5 This figure shows the structure of the signal processing unit 9a. The signal processing unit 9a includes a preamplifier 31, a linear amplifier 33, an A / D converter 35, and a memory 37. The preamplifier 31 is a charge amplifier that generates and outputs a voltage signal based on a pulse signal. This pulse signal is a charge signal output from the anode 8 in response to the electrons e1 input to the MCP 3. The linear amplifier 33 shapes the waveform of the voltage signal output from the preamplifier 31 into a pulse-shaped signal. The A / D converter 35 detects the peak value of the voltage signal shaped by the linear amplifier and accumulates the frequency of the peak value detected within a predetermined time for each peak value. The memory 37 stores the frequency of each peak value accumulated by the A / D converter 35. The frequency distribution of each peak value stored in the memory 37 is output to an external display device 39, etc. The peak value of the PHD characteristic generated by the signal processing unit 9a represents the average gain (peak channel number) of the MCP detector 1. The average gain increases as the voltage applied to the MCP 3 increases. The signal processing unit 9a is also electrically connected to each of the dynodes 5 and 7, and can generate the PHD characteristics of each of the dynodes 5 and 7. Thus, the average gain of the dynodes 5 or 7 can also be analyzed as the number of output electrons.

[0048] Next, the analysis device involved in the embodiment is described. The analysis device involved in the embodiment includes the above-mentioned MCP detector. For example, the analysis device is a mass spectrometer (MS: mass spectrometry) or a scanning electron microscope (SEM: scanning electron microscope). In addition, the analysis device can also be an X-ray photoelectron spectrometer (XPS: X-ray photoelectron spectroscopy), a photoelectron microscope (PEEM: photoemission electron microscopy), an atom probe tomography (APT: atom probe tomography), a secondary ion mass spectrometer (SIMS: secondary ion mass spectrometry), etc.

[0049] The effects of this embodiment will be described.

[0050] In the MCP detector 1 and the analysis device including the same according to the present embodiment, among the electrons e2 output from the output surface 3b based on the electrons e1 input to the input surface 3a, the electrons that pass through the anode 8 and the dynode 7 are multiplied by the dynode 5, and the multiplied electrons e3 are multiplied again by the dynode 7 and pass toward the anode 8. Then, the electrons e4 multiplied by the dynode 7 are captured by the anode 8. Thus, the number of electrons whose output electrons of the MCP3 are repeatedly multiplied by the two dynodes 5 and 7 can be reflected in the pulse signal based on the electrons obtained by the anode 8. As a result, the output linearity of the MCP detector as a whole can be improved, and the detection performance of the MCP detector 1 or the analysis device including the same can be improved.

[0051] The detection performance of existing analysis devices equipped with MCP detectors such as XPS devices has reached its peak due to the inherent output linearity of MCP. In recent years, in XPS devices, productivity has been improved by performing high brightness of X-ray probes, charging countermeasures, etc. Therefore, if the counting rate of the MCP detector can be increased, the productivity of the entire analysis device can be improved. The output linearity of the MCP detector is expressed as the product of the MCP gain and the counting rate, and the MCP gain and the counting rate are in a trade-off relationship. In addition, the inherent output linearity of the MCP built into the MCP detector is improved by reducing the resistance of the MCP channel, but the current situation is that from the perspective of maintaining the performance of the MCP when it is heated, there is a limit to the low resistance. According to this embodiment, the output linearity in the MCP detector is improved, so the counting rate can be improved while maintaining the MCP gain.

[0052] In this embodiment, the potential of dynode 7 is higher than that of output surface 3b, and the potential of anode 8 is higher than that of dynode 7. This configuration allows electrons e2 output from output surface 3b to efficiently reach dynode 7, and allows electrons e3 multiplied by dynode 7 to be efficiently captured by anode 8. As a result, the output linearity of MCP detector 1 can be improved, significantly enhancing the detection performance of MCP detector 1 or an analysis device equipped with it.

[0053] In this embodiment, the potential of dynode 7 is higher than that of dynode 5. In this case, electrons e3 multiplied by dynode 5 can efficiently reach dynode 7. As a result, the detection performance of MCP detector 1 or an analysis device equipped with the same can be further improved.

[0054] Furthermore, in this embodiment, anode 8 includes metal wires 13 extending in a first direction X along a plane, and dynode 7 includes metal wires 23 extending in a second direction Y along a plane. In this case, the output electrons e2 of the MCP 3 can be passed toward the dynode 5 with low loss, and the electrons e3 and e4 multiplied by the dynodes 5 and 7 can be obtained at anode 8 with low loss. As a result, the detection performance of the MCP detector 1 or an analysis device equipped with it can be significantly improved.

[0055] Furthermore, in this embodiment, the distance D2 between the dynode 7 and the dynode 5 is greater than the distance D1 between the anode 8 and the dynode 7. If the potential difference between the anode 8 and the dynode 7 is V1, and the potential difference between the dynode 7 and the dynode 5 is V2, V1 needs to be set to several tens of volts, and V2 needs to be set to 100 to 500 volts, resulting in V1 < V2. This is because, to increase the overall gain, the potential difference Va between the output surface 3b and the dynode 5 needs to be increased, and to increase the gain of the dynode 5, V2 ≈ Va needs to be set. In this case, the distance between the dynode 7 and the dynode 5 can be ensured, and even when the potential difference between the dynode 7 and the dynode 5 is set high to increase the gain of the dynode 5, the withstand voltage can be improved.

[0056] In this embodiment, anode 8 is arranged closer to dynode 5 than virtual surface 50. This improves the incidence efficiency (transmittance) of electrons output from output surface 3b of MCP 3 onto dynode 5, further enhancing the detection performance of MCP detector 1.

[0057] In this embodiment, the dynode 7 further includes an insulating support member 53 for supporting the dynode 7. As viewed from the output surface 3b, the support member 53 is positioned further outward from the region on the surface of the dynode 5 where the secondary electron emission film 5b is provided. This structure improves the collection efficiency of the electrons e3, which are multiplied and diffused by the dynode 5, within the dynode 7, further enhancing the detection performance of the MCP detector 1.

[0058] In this embodiment, the anode 8 further includes an insulating support member 55 for supporting the anode 8. As viewed from the output surface 3b, the support member 55 is positioned further outward from the region on the surface of the dynode 5 where the secondary electron emission film 5b is provided. This structure improves the collection efficiency of the electrons e4, which are multiplied and diffused by the dynode 5 and then pass through the dynode 7, in the anode 8, thereby further improving the detection performance of the MCP detector 1.

[0059] Figure 6This is a graph showing the measurement results of the gain (the count of electrons contained in the pulse signal) in each electrode when only the potential of the dynode 7 is changed in the MCP detector 1 and the positions of the other electrodes are fixed. Here, the vertical axis represents the absolute value of the gain obtained in each electrode, and the horizontal axis represents the potential of the dynode 7. In the numerical value of each gain, it is defined as a positive value when electrons are emitted from the electrode and as a negative value when electrons are absorbed by the electrode. In addition, in this measurement system, the secondary electron multiplication rate of the dynode 5 for the electrons output from the MCP3 is about 2 times. That is, the dynode 5 emits twice the number of electrons absorbed, but the difference between the absorbed and emitted electrons is measured as the gain, so the measurement result is 1 / 2 relative to the actual gain. According to the measurement result, when the potential of the dynode 7 is reduced from +2400V, which is the same potential as the anode 8, the gain of the dynode 5 does not change, while the gain of the anode 8 increases. Here, assuming that dynode 7 does not have the function of multiplying electrons, electrons output from dynode 5 are absorbed by dynode 7 and anode 8. Based on the measurement principle, the total number of electrons output from dynode 5 to dynode 7 and anode 8, that is, the sum of the number of electrons absorbed by dynode 7 and the number of electrons absorbed by anode 8, is assumed to always be equal to twice the gain of dynode 5 (dashed line), and should be approximately constant regardless of the potential of dynode 7. However, the gain of dynode 7 becomes a negative value, indicating electron absorption, when the potential of dynode 7 is +2.350 V or higher. On the other hand, it becomes a positive value, indicating electron emission, when the potential of dynode 7 is within the range of +2100 V to +2300 V, which is lower than +2350 V. Furthermore, the gain of anode 8 is greater than the output based on the measurement principle, that is, the dashed line. Therefore, it can be seen that anode 8 absorbs more electrons than the total number of electrons output from dynode 5 (twice the gain of dynode 5), and this increase roughly corresponds to the value of the positive gain of dynode 7. On the other hand, if the potential of dynode 7 is lower than the potential of dynode 5, +2112 V, the energy of electron emission decreases. This shows that within the range of the potential of dynode 7 from +2112 V to +2300 V, dynode 7 multiplies electrons, and accordingly, the gain of anode 8 also increases.

[0060] Figure 7 Graph showing the measurement results of the PHD characteristics in the MCP detector 1 . Figure 7 The horizontal axis of the graph shown represents gain, and the vertical axis represents detection counts. Gain is the number of electrons contained in a pulse signal of 1 count, and is defined as the peak position of the wave height distribution in the detection result. Curves G1 and G2 represent the output measurement results of the dynode 7 and anode 8 when the potential of the dynode 7 is set to the same potential of +2400V as the anode 8, and the potential of the dynode 5 is set to +2112V in this embodiment. In addition, Figure 8Curves G3 and G4 show the output measurement results of the dynode 7 and anode 8 when the potential of the dynode 7 is set to +2304 V, which is lower than the potential of the anode 8 of +2400 V, and the potential of the dynode 5 is set to +2112 V in this embodiment. These measurement results show that by setting the potential of the dynode 7 lower than the potential of the anode 8, the gain of the anode 8 can be further improved.

[0061] Although various embodiments of the present invention have been described above, the present invention is not necessarily limited to the above-described embodiments and can be modified within the scope of the gist of the claims or can be applied to other embodiments.

[0062] Figure 9 It is a plan view showing the structure of a modified example of the anode. Figure 9 The anode 107 shown is configured to include: linear anodes 107a, which are metal patterns formed on a plurality of insulators 109 extending parallel to each other at predetermined intervals along a first direction X; and linear anodes 107b, which are metal patterns extending parallel to each other at predetermined intervals along a second direction Y. The plurality of linear anodes 107a and the plurality of linear anodes 107b are insulated from each other by the insulator 109. However, the plurality of linear anodes 107a and the plurality of linear anodes 107b can also be insulated from each other by a space between them. Furthermore, the plurality of linear anodes 107a and the plurality of linear anodes 107b are each electrically and independently connected to the control unit 9. In this modified example, the signal processing unit 9a of the control unit 9 detects a pulse signal for each of the plurality of linear anodes 107a and the plurality of linear anodes 107b. Based on each pulse signal, the signal processing unit 9a measures the charge distribution of each line of the plurality of linear anodes 107a and each line of the plurality of linear anodes 107b, thereby calculating the input position of electrons into the MCP.

[0063] In addition, the signal processing unit 9a of the MCP detector 1 has two layers on the anode 8. Figure 2 In the case of the structure of the line anode 8a shown in part (a) or (b), in the case of having Figure 2 In the case of the structure shown in part (d) of , it is also possible to have a function of generating a two-dimensional histogram as described below.

[0064] Figure 10 This figure is used to explain the calculation method of the input position of the signal processing unit 9a based on the pulse signal output from the two-layer line anode 8a. When the output electron cloud Ce from the MCP3 is captured by the two-layer line anode 8a, the pulse signal P corresponding to the captured amount in the other line anode 8a is generated. x1 The electrons are transmitted from the output electron cloud Ce to one end X1 of the line anode 8a. At the same time, a pulse signal P corresponding to the captured amount is generated. x2The electron cloud Ce is transmitted from the output position to the other end X2 of the line anode 8a. At the same time, the pulse signal P corresponding to the amount of capture in the other line anode 8a is y1 The electron cloud Ce is transmitted to one end Y1 of the line anode 8a, and the pulse signal P corresponding to the captured amount is y2 The electrons are transmitted from the position of the output electron cloud Ce to the other end Y2 of the line anode 8a.

[0065] The signal processing unit 9a detects the pulse signal P at a predetermined counting rate. x1 、P x2 、P y1 、P y2 , according to the detection timing t of these pulse signals x1 , t x2 , t y1 , t y2 , using the following equations (1) and (2), the two-dimensional coordinates (x, y) representing the input position of the output electron cloud Ce are calculated using the propagation time difference. x 、C y is a given constant.

[0066] x=C x ·(t x1 -t x2 )…(1)

[0067] y=C y ·(t y1 -t y2 )…(2)

[0068] The count rate calculated for the two-dimensional coordinates in the signal processing unit 9 a is set in advance to a value that does not capture the next output electron cloud during detection of one output electron cloud Ce, according to the characteristics of the MCP 3 .

[0069] Furthermore, the signal processing unit 9a calculates a two-dimensional histogram by counting the two-dimensional coordinates calculated using the above method within a predetermined time, and generates an image representing the calculated two-dimensional histogram. Through this image, the two-dimensional position distribution of the electrons input to the MCP3 within the predetermined time can be grasped.

[0070] Figure 11 as well as Figure 12 It is a diagram showing an example of display of an image generated by the signal processing unit 9a. Figure 11 This is an example of an image display when a two-dimensional histogram is generated with a bin size of 250 ps (picoseconds). Figure 12 This is an example of an image display when a 2D histogram is generated with a bin size of 50 ps. As shown above, a larger bin size results in a larger count, while a smaller bin size results in a higher resolution image.

[0071] The MCP detector 1 according to the above-described modified example can improve the count rate while maintaining the MCP gain. By maintaining the MCP gain, the number of line anodes spanned by the input electron cloud can be maintained. As a result, the resolution (positional accuracy, spatial resolution) of the image representing the two-dimensional coordinates of the electrons generated by the MCP detector 1 can be maintained.

[0072] In this embodiment, the MCP detector 1 is described as detecting electrons as the charged particles to be detected. However, when the MCP detector 1 is used as an ion detector, the charged particles input to the detector are ions. The input ions are converted into secondary electrons near the input surface of the MCP, and electrons are output from the output surface of the MCP.

[0073] In the above embodiment, the potential of the second dynode is preferably higher than the potential of the output surface, and the potential of the anode is preferably higher than the potential of the second dynode. This configuration allows electrons output from the output surface to efficiently reach the second dynode, and the anode can efficiently capture electrons multiplied by the second dynode. As a result, the detection performance of the MCP detector or an analytical device equipped with it can be significantly improved.

[0074] In the above embodiment, the potential of the second dynode is preferably higher than that of the first dynode. In this case, electrons multiplied by the first dynode can efficiently reach the second dynode. As a result, the detection performance of the MCP detector or an analytical device equipped with the same can be further improved.

[0075] In the above embodiment, it is also preferred that the anode include a thin metal wire extending in a direction parallel to the plane, and the second dynode include a thin metal wire extending in a direction parallel to the plane. In this case, the output electrons of the MCP can be passed to the first dynode with low loss, and the electrons multiplied by the first and second dynodes can be obtained at the anode with low loss. As a result, the detection performance of the MCP detector or an analysis device equipped with it can be significantly improved.

[0076] Furthermore, in the above embodiment, it is also preferable that the distance between the second dynode and the first dynode is greater than the distance between the anode and the second dynode. In this case, the distance between the second dynode and the first dynode can be ensured, and even when the potential difference between the second dynode and the first dynode is set high to increase the gain of the first dynode, the withstand voltage can be increased.

[0077] In the above embodiment, the anode is preferably positioned closer to the first dynode than to the position between the output surface and the first dynode or the position between the first dynode. This improves the incidence efficiency of electrons output from the output surface of the MCP onto the first dynode, further enhancing the detection performance of the MCP detector.

[0078] In the above embodiment, the second dynode preferably further includes an insulating support member for supporting the second dynode, and the support member is positioned further outward from the region on the surface of the first dynode where the secondary electron emission film is located, as viewed from the output surface. This structure improves the collection efficiency of electrons multiplied by the first dynode, further enhancing the detection performance of the MCP detector.

[0079] In the above embodiment, the anode preferably further includes an insulating support member for supporting the anode, and the support member is positioned outward of the region on the surface of the first dynode where the secondary electron emission film is located, as viewed from the output surface. This configuration improves the collection efficiency of electrons multiplied by the first dynode, further enhancing the detection performance of the MCP detector.

[0080] The MCP detector of the embodiment [1] is "an MCP detector comprising: a microchannel plate having: an input surface to which charged particles are input; a multiplying portion for multiplying electrons generated in response to the input of the charged particles; and an output surface for outputting the electrons multiplied by the multiplying portion; a planar first dynode separated from the output surface and arranged approximately parallel to the output surface and multiplying the electrons output from the output surface; an anode disposed between the output surface and the first dynode, separated from the output surface and the first dynode, and collecting the electrons multiplied by the first dynode; and a second dynode disposed between the anode and the first dynode, separated from the anode and the first dynode, and further multiplying the electrons multiplied by the first dynode and passing them toward the anode".

[0081] The MCP detector of an embodiment may also be [2], "the MCP detector according to [1], wherein the potential of the second dynode is higher than the potential of the output surface, and the potential of the anode is higher than the potential of the second dynode."

[0082] The MCP detector of the embodiment may also be [3], “the MCP detector according to [2], wherein the potential of the second dynode is higher than the potential of the first dynode.”

[0083] The MCP detector of an embodiment may also be [4], "an MCP detector according to any one of [1] to [3] above, wherein the anode includes a metal wire extending in a direction along the plane, and the second dynode includes a metal wire extending in a direction along the plane."

[0084] The MCP detector of an embodiment may also be [5], "an MCP detector according to any one of [1] to [4] above, wherein the distance between the second dynode and the first dynode is greater than the distance between the anode and the second dynode."

[0085] An MCP detector of an embodiment may also be [6], "an MCP detector according to any one of [1] to [5] above, wherein the anode is arranged at a position closer to the first dynode than a position between the output surface and the first dynode and a position between the first dynode."

[0086] The MCP detector of the embodiment may also be [7], "an MCP detector according to any one of [1] to [6] above, wherein the second dynode further comprises an insulating support member for supporting the second dynode, and the support member is arranged at a position closer to the outside than the area on the surface of the first dynode where the secondary electron emission film is provided, as viewed from the output surface."

[0087] The MCP detector of an embodiment may also be [8], "an MCP detector according to any one of [1] to [7] above, wherein the anode further comprises an insulating support member for supporting the anode, and the support member is arranged at a position closer to the outside than the area on the surface of the first dynode where the secondary electron emission film is provided, as viewed from the output surface."

[0088] The analysis device of the embodiment may also be [9], "an analysis device comprising the MCP detector described in any one of [1] to [8] above."

[0089] Description of Reference Numerals

[0090] 1…MCP detector, 3…MCP, 3a…input surface, 3b…output surface, 5…dynode (first dynode), 7…dynode (second dynode), 8, 107…anode, 8a, 107a, 107b…wire anode, linear anode (metal wire), 23…metal wire (metal wire), 9…control unit, 9a…signal processing unit, 11A, 11B…multiplier unit, 13…metal wire (metal wire), e1, e2, e3, e4…electrons, X…first direction, Y…second direction.

Claims

1. An MCP detector, wherein: have: A microchannel plate having: an input surface to which charged particles are input; a multiplying portion for multiplying electrons generated in response to the input of the charged particles; and an output surface for outputting the electrons multiplied by the multiplying portion; a planar first dynode separated from the output surface and arranged substantially parallel to the output surface, and multiplying electrons output from the output surface; an anode disposed between the output surface and the first dynode, separated from the output surface and the first dynode, and collecting electrons multiplied by the first dynode; The second dynode is disposed between the anode and the first dynode and is separated from the anode and the first dynode. The second dynode further multiplies the electrons multiplied by the first dynode and passes the electrons toward the anode.

2. The MCP detector according to claim 1, wherein The potential of the second dynode is higher than the potential of the output surface, and the potential of the anode is higher than the potential of the second dynode.

3. The MCP detector according to claim 2, wherein The potential of the second dynode is higher than the potential of the first dynode.

4. The MCP detector according to any one of claims 1 to 3, wherein The anode includes a metal thin wire extending in a direction along the plane, The second dynode includes a metal thin wire extending in a direction along the plane.

5. The MCP detector according to any one of claims 1 to 4, wherein The distance between the second dynode and the first dynode is greater than the distance between the anode and the second dynode.

6. The MCP detector according to any one of claims 1 to 5, wherein The anode is arranged at a position closer to the first dynode than a position between the output surface and the first dynode and a position between the first dynode.

7. The MCP detector according to any one of claims 1 to 6, wherein The second dynode further includes an insulating support member for supporting the second dynode. The support member is provided at an outer side of a region where the secondary electron emitting film is provided on the surface of the first dynode, as viewed from the output surface.

8. The MCP detector according to any one of claims 1 to 7, wherein The anode further includes an insulating support member for supporting the anode. The support member is provided at an outer side of a region where the secondary electron emitting film is provided on the surface of the first dynode, as viewed from the output surface.

9. An analysis device, wherein: A MCP detector according to any one of claims 1 to 8.

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