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); and an electron collection unit (7) that is disposed between the output surface (3b) and the dynode (5), is separated from the output surface (3b) and the dynode (5), and collects the electrons (e3) multiplied by the dynode (5), the electron collection unit (7) having: a line anode (7a) that includes a metal line extending along a plane substantially parallel to the output surface (3b); and a wire anode (7b) that is electrically insulated from the wire anode (7a), includes a metal wire extending along the plane, and is disposed between the wire anode (7a) and the dynode (5).

Description

TECHNICAL FIELD

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

[0002] In an analysis device such as an XPS device (X-ray Photoelectron Spectroscopy) equipped with a microchannel plate (MCP), improvement in output linearity of the microchannel plate is required. In order to improve the output linearity of the microchannel plate, low-resistance of the microchannel plate has been studied, but improvement in the output linearity based on the low-resistance has reached a limit.

[0003] Conventionally, a triode structure in which an anode and a dynode are combined on a microchannel plate has been studied. As an existing charged particle detector having a triode configuration, for example, an electron multiplication device described in Patent Literature 1 is known. The electron multiplication device is equipped with an MCP, and a dynode and a lattice-shaped anode disposed in parallel with an output surface of the MCP.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 57-196466 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] In the existing electron multiplication device as described above, the detection performance of the detector equipped with the MCP reaches a limit due to the limit of the output linearity inherent to the MCP. Therefore, improvement in the detection performance of the detector equipped with the MCP is desired.

[0009] Therefore, one aspect of the embodiments is achieved 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 FOR SOLVING PROBLEMS

[0011] The MCP detector according to the first aspect of the embodiments, wherein the MCP detector comprises: a microchannel plate having an input surface to which charged particles are input, a multiplication section that multiplies electrons generated in accordance with the input of the charged particles, and an output surface that outputs the electrons multiplied by the multiplication section; a planar dynode disposed apart from the output surface and substantially parallel to the output surface and multiplying the electrons output from the output surface; and an electron collecting section disposed apart from the output surface and the dynode between the output surface and the dynode and collecting the electrons multiplied by the dynode, the electron collecting section having: a first anode including a metal wire extending along a plane substantially parallel to the output surface; and a second anode electrically insulated from the first anode, including a metal wire extending along the plane, and disposed between the first anode and the dynode.

[0012] Alternatively, the analysis device according to the second aspect of the embodiments includes the MCP detector described above.

[0013] According to the first aspect or the second aspect described above, among the electrons output from the output surface of the microchannel plate (hereinafter, also referred to as "MCP") in accordance with the charged particles input to the input surface of the MCP, the electrons that pass through the first anode and the second anode are multiplied by the dynode, and the multiplied electrons are captured by the second anode and the first anode. Thereby, in the output signal based on the electrons obtained by the first anode and the second anode, the number of the electrons multiplied by the output electrons of the MCP can be reflected. As a result, the output linearity of the MCP detector as a whole can be improved. As a result, the detection performance of the MCP detector or the analysis device including the same can be improved.

[0014] Effects of Invention

[0015] According to any of the aspects of the present disclosure, the detection performance of the detector including the MCP can be improved. BRIEF DESCRIPTION OF DRAWINGS

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

[0017] Figure 2 is a plan view showing the detailed structure of the wire anodes 7a, 7b.

[0018] Figure 3 is a cross-sectional view showing the support structure of the electron collecting section 7.

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

[0020] Figure 5is a diagram for explaining an operation method of an input position of the signal processing section 9a based on a pulse signal output from the linear anode 7a, 7b.

[0021] Figure 6 is a diagram showing an example of an image generated by the signal processing section 9a.

[0022] Figure 7 is a diagram showing an example of an image generated by the signal processing section 9a.

[0023] Figure 8 is a chart showing a wave height distribution used for measurement of gain in the MCP detector 1.

[0024] Figure 9 is a chart showing measurement results of gain in each electrode when the potential of the linear anode 7b is changed in the MCP detector 1.

[0025] Figure 10 is a chart showing measurement results of gain in the MCP detector 1.

[0026] Figure 11 is a chart showing measurement results of gain in the MCP detector 1.

[0027] Figure 12 is a plan view showing a structure of a modification example of the electron collecting section. DETAILED DESCRIPTION

[0028] Hereinafter, an embodiment of the present application will be described in detail with reference to the drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and repeated description will be omitted.

[0029] Figure 1 is a cross-sectional view showing a structure of the MCP detector 1 according to the embodiment. In Figure 1 , a circuit section is illustrated by a block. The MCP detector 1 is a device that detects an input charged particle. In the present embodiment, the MCP detector 1 detects a two-dimensional position of an input charged particle. The charged particle of the detection object can include an electron or an ion, or the like. In the present embodiment, an electron is exemplified as the detection object of the MCP detector 1.

[0030] As shown in Figure 1 , the MCP detector 1 includes an MCP 3, a dynode 5, an electron collecting section 7, and a control section 9. These MCP 3, dynode 5, and electron collecting section 7 are each generally planar as a whole, and are arranged in a generally parallel manner with respect to each other. Hereinafter, each structural element of the MCP detector 1 will be described.

[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] The electron collector 7 is an electrode disposed between the output surface 3b of the MCP 3 and the dynodes 5, separated from the MCP 3 and the dynodes 5. It collects (captures) electrons multiplied by the secondary electron emission film 5b of the dynodes 5 and emitted toward the output surface 3b. The electron collector 7 is disposed closer to the dynodes 5 than to the center between the output surface 3b and the dynodes 5. The electron collector 7 comprises a wire anode (first anode) 7a extending in a first direction X along a plane generally parallel to the output surface 3b; and a wire anode (second anode) 7b electrically insulated from the wire anode 7a, extending in a second direction Y substantially perpendicular to the first direction X along a plane generally parallel to the output surface 3b, and disposed between the wire anode 7a and the dynodes 5.

[0035] The wire anodes 7a, 7b are members in which a coating (gold plating) 15 for preventing oxidation is applied to a metal thin wire (metal wire) 13 of copper, nickel, chromium, SUS, or the like. For example, the wire width of the wire anodes 7a, 7b is in a range of 50 μm or more and 200 μm or less. The wire anode 7a extends in the X direction at a plurality of positions separated by a prescribed interval (for example, an interval of 200 μm or more and 1 mm or less) in the Y direction, and is electrically connected as a whole. The wire anode 7b extends in the Y direction at a plurality of positions separated by a prescribed interval (for example, an interval of 200 μm or more and 1 mm or less) in the X direction, and is electrically connected as a whole. In other words, the wire anode 7a extends in a direction that intersects the extending direction of the wire anode 7b at substantially right angles in a plane that is substantially parallel to the output surface 3b, and the wire anode 7a and the wire anode 7b are arranged separately in a direction that is perpendicular to the output surface 3b.

[0036] Figure 2 is a plan view that shows the specific structure of the wire anodes 7a, 7b. The wire anodes 7a, 7b are respectively configured as shown in Figure 2 (a) part of FIG. 7. The metal thin wire can be arranged in a zigzag pattern in a manner that bridges between opposite pair of edges of a frame-shaped insulating support member (not shown). In this case, both ends of the metal thin wire are electrically connected to the control section 9. Alternatively, the wire anodes 7a, 7b can be respectively configured as shown in Figure 2 (b) part of FIG. 7. The metal thin wire is wound in a manner that does not overlap each other on opposite pair of edges of a frame-shaped insulating support member (not shown). In this case, both ends of the metal thin wire are also electrically connected to the control section 9. Alternatively, the wire anodes 7a, 7b can be configured as shown in Figure 2 (c) part of FIG. 7. A plurality of straight metal thin wires are arranged at a prescribed interval, and these plurality of metal thin wires are electrically connected to each other in a zigzag metal pattern. The straight metal thin wires that constitute the wire anode 7a and the straight metal thin wires that constitute the wire anode 7b are electrically insulated from each other with an insulating member (not shown) interposed therebetween. In this case, both ends of the zigzag metal pattern of each of the wire anodes 7a, 7b are electrically connected to the control section 9.

[0037] Here, the distance D2 between the wire anode 7b and the dynode 5 is set to be greater than the distance Dl between the wire anode 7a and the wire anode 7b. In addition, the electron collecting section 7 that includes the wire anodes 7a and 7b is arranged as a whole in the vicinity of the dynode 5, as compared with a virtual plane 20 that corresponds to a position that is intermediate between the output surface 3b and the secondary electron emission film 5b of the dynode 5 and a position that is intermediate between the secondary electron emission film 5b of the dynode 5 and the output surface 3b.

[0038] Referring to Figure 3 , the support structure of the electron collecting section 7 will be described. Figure 3is a cross-sectional view showing a supporting structure of the electron collecting section. The electron collecting section 7 also has a supporting member 23 made of an insulating material that supports the wire anode 7b and a supporting member 25 made of an insulating material that supports the wire anode 7a. These supporting members 23, 25 are provided so as to be located more outward of the region of the face of the MCP 3 near the multiplication stage 5, on which the secondary electron emission film 5b is provided, when the multiplication stage 5 is viewed from the output face 3b. In addition, the supporting member 23 and the supporting member 25 can be a common member.

[0039] The control section 9 is electrically connected to the input face 3a and the output face 3b of the MCP 3, the multiplication stage 5, the wire anodes 7a, 7b of the electron collecting section 7, is a circuit that sets the potentials of each of them, and processes the pulse signals output from the wire anodes 7a, 7b. The control section 9 has a signal processing section 9a built therein that processes the pulse signals output from the wire anodes 7a, 7b to generate an image showing the two-dimensional position of the electron input to the input face 3a of the MCP 3.

[0040] That is, the control section 9 applies voltages to the input face 3a, the output face 3b, the multiplication stage 5, and the wire anodes 7a, 7b in such a manner that the potential of the output face 3b is higher than that of the input face 3a, the potential of the multiplication stage 5 is higher than that of the output face 3b, the potential of the electron collecting section 7 is higher than that of the multiplication stage 5, and the potential of the wire anode 7a is higher than that of the wire anode 7b. In other words, the control section 9 sets the potentials of each of them in such a manner that the potentials become higher in the order of the input face 3a, the output face 3b, the multiplication stage 5, the wire anode 7b, and the wire anode 7a. For example, the control section 9 sets the potential of the input face 3a to 0 V, the potential of the output face 3b to +1920 V, the potential of the multiplication stage 5 to +2112 V, the potential of the wire anode 7a to +2400 V, and the potential of the wire anode 7b to a potential higher than +2112 V and lower than +2400 V.

[0041] Figure 4 is a cross-sectional view showing the multiplication state of the secondary electrons in one channel of the multiplication sections 11A, 11B of the MCP 3, for which the potentials are set by the control section 9. An electrode 19 is provided at the end of the channel 17 on the input face 3a side of the multiplication sections 11A, 11B, and an electrode 21 is provided at the end of the channel 17 on the output face 3b side of the multiplication sections 11A, 11B, and 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 that makes the potential of the electrode 19 lower between the electrode 19 of the multiplication section 11A and the electrode 21 of the multiplication section 11B. As a result, a voltage V D is applied between the both ends of the channel 17 of each of the multiplication sections 11A, 11B, and a band-shaped current I SWhen an electron el is input from the end of the input face 3a side of the channel 17 in such a state, the electron el collides with the inner wall portion of the channel 17, whereby the electron is multiplied, and the secondary electron e2 generated by repeatedly performing multiplication of the electron at the inner wall portion of the channel 17 is output from the end of the output face 3b side of the channel 17. The output electron of the multiplication portion 11A, 11B is generated by taking out a part of the band-shaped current I S , and thus the output linearity of the MCP 3 is to the extent of 7% of the value of the band-shaped current I S . Therefore, in order to improve the output linearity of the MCP 3 itself, it is necessary to reduce the resistance value of the inner wall portion of the channel 17. Further, the output linearity refers to an upper limit of the output electron number per unit time which can output the input electron number and the output electron number while maintaining a linear relationship.

[0042] The signal processing portion 9a of the control portion 9 processes the pulse signals output from both ends of the two wire anodes 7a, 7b in accordance with the electrons collected by the wire anodes 7a, 7b, and generates an image indicating two-dimensional coordinates of the input position of the electron to the input face 3a of the MCP 3.

[0043] Figure 5 is a view for explaining an operation method of the input position of the signal processing portion 9a based on the pulse signals output from the wire anodes 7a, 7b. When the output electron cloud Ce from the MCP 3 is captured by the two wire anodes 7a, 7b, a pulse signal P x1 corresponding to the amount of capture in the wire anode 7a is transmitted from the position of the output electron cloud Ce to one end XI of the wire anode 7a, and at the same time, a pulse signal P x2 corresponding to the amount of capture is transmitted from the position of the output electron cloud Ce to the other end X2 of the wire anode 7a. At the same time, a pulse signal P y1 corresponding to the amount of capture in the wire anode 7b is transmitted from the position of the output electron cloud Ce to one end Yl of the wire anode 7b, and at the same time, a pulse signal P y2 corresponding to the amount of capture is transmitted from the position of the output electron cloud Ce to the other end Y2 of the wire anode 7b.

[0044] The signal processing portion 9a detects the above-described pulse signals P x1 , P x2 , P y1 , P y2 at a prescribed count rate, and calculates two-dimensional coordinates (x, y) indicating the input position of the output electron cloud Ce using the following equations (1), (2) using the difference in propagation time based on the detection timings t x1 , t x2 , t y1 , t y2 of these pulse signals. Here, C x , C y are constants.

[0045] x = C x • (t x1 -t x2 )... (1)

[0046] y = C y • (t y1 -t y2 )... (2)

[0047] As for the calculated count rate of the two-dimensional coordinates in the signal processing section 9a, a value in which the next output electron cloud is not captured in the detection of one output electron cloud Ce is set in advance in accordance with the characteristics of the MCP 3.

[0048] In addition, the signal processing section 9a calculates a two-dimensional histogram by counting the two-dimensional coordinates calculated by the above method within a prescribed time, and generates an image representing the calculated two-dimensional histogram. With this image, the two-dimensional positional distribution of the electrons input to the MCP 3 within the prescribed time can be grasped.

[0049] Figure 6 and Figure 7 is a diagram representing an example of the image generated by the signal processing section 9a. Figure 6 is an example of image display when a two-dimensional histogram is generated with a bin size of 250 ps (picoseconds), Figure 7 is an example of image display when a two-dimensional histogram is generated with a bin size of 50 ps. As such, the larger the bin size, the greater the count, and the smaller the bin size, the higher the resolution of the image.

[0050] Next, the analysis device according to the embodiment will be described. The analysis device according to the embodiment is provided with the MCP detector described above. The analysis device is, for example, an X-ray photoelectron spectroscopy (XPS), a photoelectron microscope (PEEM), an atom probe tomography (APT), a secondary ion mass spectrometer (SIMS), or the like.

[0051] The effects of the present embodiment will be described.

[0052] In the MCP detector 1 according to the present embodiment and the analysis device including the same, the electrons e2 output from the output surface 3b in accordance with the input of the electrons el to the input surface 3a are multiplied by the dynodes 5, and the multiplied electrons e3 are captured by the wire anodes 7b and 7a. Thus, in the pulse signal based on the electrons obtained by the wire anodes 7a and 7b, the number of electrons multiplied by the output electrons of the MCP 3 can be reflected. As a result, the output linearity of the MCP detector as a whole can be improved. As a result, the detection performance of the MCP detector 1 or the analysis device including the same can be improved.

[0053] The detection performance of the conventional analysis device equipped with the MCP detector like the XPS device reaches the peak due to the output linearity inherent to the MCP. In recent years, in the XPS device, the improvement of the productivity has been realized by performing the high-brightness of the X-ray probe, the countermeasures against charging, and the like. Therefore, if the count rate of the MCP detector can be improved, the productivity of the analysis device as a whole can be improved. The output linearity of the MCP detector is expressed by the product of the MCP gain and the count rate, and the MCP gain and the count rate are in a trade-off relationship. In addition, the output linearity inherent to the MCP built in the MCP detector is improved by the low-resistance of the channel of the MCP, but the present situation is that, from the viewpoint of maintaining the performance at the time of heating of the MCP, there is a limit to the low-resistance. According to the present embodiment, the output linearity in the MCP detector is improved, and thus the count rate can be improved while maintaining the MCP gain. By maintaining the MCP gain, the number of the wire anodes across which the input electron cloud passes can be maintained, and the resolution (position accuracy, spatial resolution) in the image representing the two-dimensional coordinates of the electrons generated by the MCP detector can be maintained.

[0054] In the present embodiment, the potential of the dynodes 5 is higher than the potential of the output surface 3b, and the potential of the electron collecting portion 7 is higher than the potential of the dynodes 5. By such a configuration, the electrons e2 output from the output surface 3b can efficiently reach the dynodes 5, and the electrons e3 multiplied by the dynodes 5 can be efficiently captured by the electron collecting portion 7. As a result, the output linearity of the MCP detector can be improved, and the detection performance of the MCP detector 1 or the analysis device including the same can be greatly improved.

[0055] In addition, in the present embodiment, the potential of the wire anode 7a is higher than the potential of the wire anode 7b. In this case, the wire anode 7a and the wire anode 7b can capture the electrons e3 multiplied by the dynode 5 in a balanced manner. As a result, the detection performance of the MCP detector 1 or the analysis device provided with the same can be improved in a balanced manner. In particular, the number of electrons obtained by the two wire anodes 7a, 7b based on the input electron cloud can be set to 1 : 1, and distortion in the X coordinate direction or the Y coordinate direction in an image representing two-dimensional coordinates of the electrons generated by the MCP detector can be reduced.

[0056] In addition, in the present embodiment, the wire anode 7a includes a metal fine wire 13 extending in a first direction X along a plane, and the wire anode 7b includes a metal fine wire 13 extending in a second direction Y intersecting the first direction X along the plane. In this case, the position information of the electrons input based on the two pulse signals generated by the wire anode 7a and the wire anode 7b can be obtained with high precision.

[0057] In addition, in the present embodiment, the distance D2 between the wire anode 7b and the dynode 5 is larger than the distance Dl between the wire anode 7a and the wire anode 7b. If the potential difference between the two wire anodes 7a, 7b is set to VI, and the potential difference between the wire anode 7b and the dynode 5 is set to V2, it is necessary to set VI to several tens of V, and V2 to 100 to 500 V, so that VI < V2. This is because, in order to increase the overall gain, it is necessary to increase the potential difference Va between the output surface 3b and the dynode 5, and in order to increase the gain of the dynode 5, it is necessary to make V2 ≒ Va. In this case, the distance between the electron collecting portion 7 and the dynode 5 can be ensured, and the voltage resistance can be improved even in a case where the potential difference between the electron collecting portion 7 and the dynode 5 is set to be high in order to increase the gain of the dynode 5.

[0058] In addition, in the present embodiment, the electron collecting portion 7 is disposed overall closer to the dynode 5 than the virtual surface 20. In this way, the incidence efficiency (transmittance) of the electrons output from the output surface 3b of the MCP 3 to the dynode 5 is improved, and the detection performance of the MCP detector 1 can be further improved.

[0059] In addition, in the present embodiment, the electron collecting portion 7 further has an insulating support member 23 that supports the wire anode 7b, and the support member 23 is disposed at a position closer to the outside than a region in which the surface of the dynode 5 is provided with the secondary electron emission film 5b, as viewed from the output surface 3b. If such a structure is employed, the collection efficiency of the electrons e3 multiplied and diffused by the dynode 5 in the electron collecting portion 7 can be improved, and the detection performance of the MCP detector 1 can be further improved.

[0060] In addition, in the present embodiment, the electron collecting portion 7 also has an insulating support member 25 that supports the wire anode 7a, and the support member 25 is disposed at a position that is closer to the outside than the region in which the dynode 5 has the secondary electron emission film 5b, as viewed from the output surface 3b. If such a structure is employed, the collection efficiency of the electrons e3 that are multiplied and diffused by the dynode 5 in the electron collecting portion 7 can be improved, and the detection performance of the MCP detector 1 can be further improved.

[0061] Figure 8 is a graph that indicates the wave height distribution (pulse height distribution) of the gain in the MCP detector 1, which is used for measurement. Figure 8 The horizontal axis of the graph indicates the gain, and the vertical axis indicates the detection count. The gain is the count of the electrons contained in the pulse signal of 1 count, and is defined as the peak position of the wave height distribution. The curve Gl indicates the wire anode 7a, 7b in the present embodiment, and the curve G2 indicates the measurement result in a comparative example in which the pulse signals of the dynode 5 and the wire anode 7a, 7b are set to the same potential in the MCP detector 1. According to this measurement result, the gain corresponding to the peak of the wave height distribution in the present embodiment is improved by a factor of 2, as compared with the comparative example.

[0062] Figure 9 is a graph that indicates the measurement result of the gain in each electrode when the potential of the wire anode 7b is changed in the MCP detector 1. According to this measurement result, in the case where the potential of the wire anode 7b is reduced from the potential of the wire anode 7a +2400 V, the gain of the dynode 5 does not change, on the other hand, the gain of the wire anode 7a increases, and the gain of the wire anode 7b decreases. It is considered that this is because the electrons obtained by the wire anode 7b decrease and the electrons obtained by the wire anode 7a increase, by the reduction of the potential of the wire anode 7b. For example, in the case where the potential of the wire anode 7b is set to +2400 V, it is predicted that the gain of the wire anode 7b is 2 times the gain of the wire anode 7a, 2 / 3 of the number of electrons collected by the electron collecting portion 7 is obtained by the wire anode 7b, and 1 / 3 of the number of electrons is obtained by the wire anode 7a. In addition, in the case where the potential of the wire anode 7b is set to +2380 V, the gain of the wire anode 7a is approximately equal to the gain of the wire anode 7b, and it is predicted that about half of the number of electrons collected by the electron collecting portion 7 is obtained by the wire anode 7b, and the remaining about half of the number of electrons is obtained by the wire anode 7a.

[0063] Figure 10 is a graph that indicates the measurement result of the gain when the potential of the wire anode 7b is set to +2400 V in the MCP detector 1, Figure 11is a graph showing the measurement results of the gain when the potential of the linear anode 7b is set to +2380 V in the MCP detector 1. The curve G3 and the curve G5 show the detection counts of the gain of the linear anode 7b, and the curve G4 and the curve G6 show the detection counts of the gain of the linear anode 7a. According to these measurement results, it is known that when the potential of the linear anode 7b is set lower than the potential of the linear anode 7a, the gains of the two linear anodes 7a, 7b easily become uniform, as a result of which it is possible to reduce distortion in an image showing two-dimensional coordinates of electrons generated by the MCP detector.

[0064] The above describes various embodiments of the present application, but the present application is not necessarily limited to the above-described embodiments, and can be modified within the scope of the gist described in each claim, or can be applied to other embodiments.

[0065] Figure 12 is a plan view showing the structure of a modification example of the electron collecting section. Figure 12 The electron collecting section 107 shown in the drawing is configured to include a linear anode 107a that is a metal pattern formed on a plurality of insulators 109 that extend in parallel with each other at a prescribed interval along a first direction X, and a linear anode 107b that is a plurality of metal patterns that extend in parallel with each other at a prescribed interval along a second direction Y. The plurality of linear anodes 107a and the plurality of linear anodes 107b are insulated from each other with the insulators 109 interposed therebetween. However, the plurality of linear anodes 107a and the plurality of linear anodes 107b can also be insulated from each other by a space being interposed therebetween. In addition, the plurality of linear anodes 107a and the plurality of linear anodes 107b are respectively electrically independently connected to the control section 9. In this modification example, the signal processing section 9a of the control section 9 detects a pulse signal for each of the plurality of linear anodes 107a and the plurality of linear anodes 107b, and measures the distribution of the amount of charge of each of the plurality of linear anodes 107a and the plurality of linear anodes 107b based on each pulse signal, thereby calculating the input position of an electron to the MCP.

[0066] In the present embodiment, a case where the detection object of the MCP detector 1 is an electron is exemplified, but in a case where the MCP detector 1 is used as an ion detector, the charged particle input to the detector is an ion. The input ion is converted into a secondary electron at the input face of the MCP, and as a result, an electron is output from the output face of the MCP.

[0067] The wire anode 7a and the wire anode 7b can intersect each other as long as they intersect, and can not intersect substantially perpendicularly. In addition, the electron collecting portion 7 can further have a wire anode 7c (third anode) extending along a plane in a third direction intersecting both the wire anode 7a and the wire anode 7b, the potential of the wire anode 7c being higher than that of the wire anode 7b, and the potential of the wire anode 7b being higher than that of the wire anode 7a. In this case, in a case where a plurality of electrons simultaneously reach the electron collecting portion 7, they can be distinguished and detected.

[0068] In the above-described embodiment, it is preferable that the potential of the dynode be higher than the potential of the output surface, and the potential of the electron collecting portion be higher than the potential of the dynode. With such a configuration, the electrons output from the output surface can efficiently reach the dynode, and the electrons multiplied by the dynode can be efficiently captured by the electron collecting portion. As a result, the detection performance of the MCP detector or the analysis device provided with the same can be greatly improved.

[0069] In addition, in the above-described embodiment, it is preferable that the potential of the first anode be higher than the potential of the second anode. In this case, the first anode and the second anode can equally capture the electrons multiplied by the dynode. As a result, the detection performance of the MCP detector or the analysis device provided with the same can be balancedly improved.

[0070] In addition, in the above-described embodiment, it is also preferable that the first anode include a metal fine wire extending in a first direction along a plane, and the second anode include a metal fine wire extending in a second direction intersecting the first direction along the plane. In this case, the position information of the charged particle based on two detection signals input from the first anode and the second anode can be accurately obtained.

[0071] In addition, in the above-described embodiment, it is preferable that the distance between the second anode and the dynode be greater than the distance between the first anode and the second anode. In this case, the distance between the electron collecting portion and the dynode can be ensured, and the withstand voltage can be improved even in a case where the potential difference between the electron collecting portion and the dynode is set to be high in order to increase the gain of the dynode.

[0072] In addition, in the above-described embodiment, it is also preferable that the electron collecting portion be disposed closer to the dynode than an intermediate position between the output surface and the dynode and an intermediate position of the dynode. In this way, the incidence efficiency of the electrons output from the output surface of the MCP to the dynode is improved, and the detection performance of the MCP detector can be further improved.

[0073] Further, in the above embodiment, it is also preferable that the electron collecting section further has an insulating support member that supports the second anode, and the support member is disposed, as viewed from the output surface, at a position that is closer to the outside than a region on the face of the dynode on which the secondary electron emission film is provided. If such a structure is employed, the collection efficiency of the electrons multiplied by the dynode can be improved, and the detection performance of the MCP detector can be further improved.

[0074] Further, in the above embodiment, it is also preferable that the electron collecting section further has an insulating support member that supports the second anode, and the support member is disposed, as viewed from the output surface, at a position that is closer to the outside than a region on the face of the dynode on which the secondary electron emission film is provided. If such a structure is employed, the collection efficiency of the electrons multiplied by the dynode can be improved, and the detection performance of the MCP detector can be further improved.

[0075] The MCP detector of the embodiment can be [1] "an MCP detector, comprising: a microchannel plate having: an input surface to which charged particles are input; a multiplication section that multiplies electrons generated in accordance with the input of the charged particles; and an output surface that outputs the electrons multiplied by the multiplication section; a planar dynode that is separated from the output surface and disposed substantially in parallel to the output surface and multiplies the electrons output from the output surface; and an electron collecting section that is disposed separately from the output surface and the dynode between the output surface and the dynode, and collects the electrons multiplied by the dynode, the electron collecting section having: a first anode including a metal wire extending along a plane substantially parallel to the output surface; and a second anode electrically insulated from the first anode, including a metal wire extending along the plane, and disposed between the first anode and the dynode".

[0076] The MCP detector of the embodiment can be [2] "the MCP detector according to [1], wherein a potential of the dynode is higher than a potential of the output surface, and a potential of the electron collecting section is higher than the potential of the dynode".

[0077] The MCP detector of the embodiment can be [3] "the MCP detector according to [2], wherein a potential of the first anode is higher than a potential of the second anode".

[0078] The MCP detector of the embodiment can be [4] "the MCP detector according to any one of the above [1] to [3], wherein the first anode includes a metal fine wire extending in a first direction along the plane, and the second anode includes a metal fine wire extending in a second direction intersecting the first direction along the plane".

[0079] The MCP detector of the embodiment can also be [5], "The MCP detector according to any one of the above [1] to [4], wherein a distance between the second anode and the dynode is larger than a distance between the first anode and the second anode."

[0080] The MCP detector of the embodiment can also be [6], "The MCP detector according to any one of the above [1] to [5], wherein the electron collecting section is disposed closer to the dynode than a position halfway between the output surface and the dynode and a position halfway of the dynode."

[0081] The MCP detector of the embodiment can also be [7], "The MCP detector according to any one of the above [1] to [6], wherein the electron collecting section further has an insulating support member that supports the second anode, the support member being disposed, as viewed from the output surface, closer to the outside than a region on a surface of the dynode where the secondary electron emission film is provided."

[0082] The MCP detector of the embodiment can also be [8], "The MCP detector according to any one of the above [1] to [7], wherein the electron collecting section further has an insulating support member that supports the first anode, the support member being disposed, as viewed from the output surface, closer to the outside than a region on a surface of the dynode where the secondary electron emission film is provided."

[0083] The analysis device of the embodiment can also be [9], "An analysis device, wherein the MCP detector according to any one of the above [1] to [8] is provided."

[0084] Explanation of Reference Signs

[0085] 1…MCP detector, 3…MCP, 3a…input surface, 3b…output surface, 5…dynode, 7, 107…electron collecting section, 7a, 107a…wire anode, wire-shaped anode (first anode), 7b, 107b…wire anode, wire-shaped anode (second anode), 9…control section, 9a…signal processing section, 11A, 11B…multiplication section, 13…metallic fine wire (metal wire), e1, e2, e3…electron, X…first direction, Y…second direction.

Claims

1. An MCP detector, wherein provided are: a microchannel plate having an input surface into which charged particles are input, a multiplication section that multiplies electrons generated in accordance with input of the charged particles, and an output surface that outputs the electrons multiplied by the multiplication section; a planar multiplication electrode that is disposed apart from the output surface and substantially in parallel with the output surface, and multiplies the electrons output from the output surface; and an electron collecting section that is disposed apart from the output surface and the multiplication electrode between the output surface and the multiplication electrode, and collects the electrons multiplied by the multiplication electrode, the electron collecting section has: a first anode that includes metal wires extending along a plane substantially parallel with the output surface; and a second anode that is electrically insulated from the first anode, includes metal wires extending along the plane, and is disposed between the first anode and the multiplication electrode.

2. The MCP detector according to claim 1, wherein the potential of the multiplication electrode is higher than the potential of the output surface, and the potential of the electron collecting section is higher than the potential of the multiplication electrode.

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

4. The MCP detector according to any one of claims 1 to 3, wherein the first anode includes metal fine wires extending in a first direction along the plane, the second anode includes metal fine wires extending in a second direction intersecting the first direction along the plane.

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

6. The MCP detector according to any one of claims 1 to 5, wherein the electron collecting section is disposed closer to the multiplication electrode than a position intermediate the output surface and the multiplication electrode and a position intermediate the multiplication electrode.

7. The MCP detector according to any one of claims 1 to 6, wherein the electron collecting section further has an insulating support member that supports the second anode, the support member is disposed closer to the outside than a region on a surface of the multiplication electrode on which a secondary electron emission film is provided, as viewed from the output surface.

8. The MCP detector according to any one of claims 1 to 7, wherein the electron collecting section further has an insulating support member that supports the first anode, the support member is disposed closer to the outside than a region on a surface of the multiplication electrode on which a secondary electron emission film is provided, as viewed from the output surface.

9. An analysis device, wherein provided is the MCP detector according to any one of claims 1 to 8.

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