Quality analysis equipment

Abstract

This mass analysis device comprises: a vacuum container; a detector; a buffer material; a pressing member; and a compression-amount restricting mechanism. The vacuum container is used for mass analysis of a sample. The detector, buffer material, pressing member, and compression-amount restricting mechanism are accommodated in the interior of the vacuum container. The detector detects the sample to be analysed. The buffer material holds the detector. The pressing member presses the buffer material into the vacuum container. The compression-amount restricting mechanism restricts, to a certain value, the amount of pressing-compression of the buffer material, when the buffer material is press by the pressing member.

Description

[Technical field]

[0001] The present invention relates to a mass spectrometer. [Background technology]

[0002] Mass spectrometers are known as analytical devices that analyze the masses of components contained in a sample. For example, in the mass spectrometer described in Patent Document 1, an ion source, an ion separator, and a detector are arranged in a vacuum chamber. The inside of the vacuum chamber is evacuated by a vacuum pump.

[0003] Ions generated from a sample to be analyzed by an ion source are separated by mass by an ion separator. The ions separated by the ion separator are successively detected by a detector at a time difference corresponding to the mass, and a detection signal indicating the detection intensity is output. Mass profile data indicating the relationship between the mass of the ions and the detection intensity is generated based on the detection signal. [Patent Document 1] JP 2020-087573 A Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, a vacuum pump for creating a vacuum inside a vacuum chamber is attached to the vacuum chamber. Vacuum pumps such as turbo molecular pumps vibrate at a frequency of tens of thousands of times per minute. Therefore, the vibration of the vacuum pump is transmitted through the vacuum chamber to the detection unit or to a cable connected to the detection unit. If the vibration transmitted to the detection unit, etc. is large, electrical noise caused by the vibration will be mixed into the detection signal, reducing the S / N (signal / noise) ratio of the detection signal.

[0005] In addition, since the magnitude of the vibration transmitted to the detector and other components varies depending on the person who installs the vacuum pump, it is not easy to obtain mass profile data with high reproducibility. Therefore, it is necessary to reduce the effects of the vacuum pump vibration.

[0006] An object of the present invention is to provide a mass spectrometer in which the effects of vibrations of a vacuum pump are reduced. [Means for solving the problem]

[0007] One aspect of the present invention is a vacuum vessel used for mass spectrometry of a sample, a detector for detecting a sample to be analyzed, a buffer material for holding the detector, a pressing member for pressing the buffer material against the vacuum vessel, and a crushing amount regulating mechanism for regulating the amount of crushing of the buffer material by the pressing member. The vacuum container includes a first side wall and a second side wall opposed to each other, a vacuum pump for creating a vacuum inside the vacuum container is attached to an outer surface of the first side wall, and the pressing member is attached to an inner surface of the second side wall to press the buffer material. The present invention relates to a mass spectrometer. Another aspect of the present invention is a device comprising a vacuum vessel used for mass spectrometry of a sample, a detector for detecting a sample to be analyzed, a buffer material for holding the detector, a pressing member for pressing the buffer material against the vacuum vessel, and a crushing amount regulating mechanism for regulating an amount of crushing of the buffer material by the pressing member, the buffer material including a first buffer material and a second buffer material, the pressing member being a first pressing member for pressing the first buffer material against the vacuum vessel, and a second pressing member for pressing the second buffer material against the vacuum vessel. the crushing amount regulating mechanism further includes a first crushing amount regulating mechanism that regulates the amount of crushing of the first cushioning material by the first pressing member and a second crushing amount regulating mechanism that regulates the amount of crushing of the second cushioning material by the second pressing member, and the detector includes a base that is sandwiched between the first cushioning material and the second cushioning material and has a first notch and a second notch that abut against the first cushioning material and the second cushioning material, respectively. Effect of the Invention

[0008] According to the present invention, the influence of vibrations of the vacuum pump can be reduced. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a mass spectrometer according to an embodiment. [Diagram 2] FIG. 2 is a schematic perspective view showing the configuration of the detector. [Diagram 3] FIG. 3 is a partial enlarged view showing the internal structure at the downstream end of the vacuum vessel. [Figure 4] FIG. 4 is a diagram showing the configuration of the mounting fixture. [Diagram 5] FIG. 5 is a diagram for explaining a method for fixing the detector. [Figure 6] FIG. 6 is a diagram for explaining a method of fixing the detector in the first modified example. [Figure 7] FIG. 7 is a diagram for explaining a method of fixing the detector in the second modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (1) Mass spectrometer configuration A mass spectrometer according to an embodiment will be described in detail below with reference to the drawings. Fig. 1 is a schematic diagram showing the configuration of a mass spectrometer according to an embodiment. As shown in Fig. 1, the mass spectrometer 100 includes a vacuum vessel 110, a vacuum pump 120, an ion lens 130, a quadrupole mass filter 140, a detector 150, a power supply circuit 160, and a processing unit 170.

[0011] The vacuum vessel 110 is made of, for example, metal, and is maintained at ground potential. The vacuum vessel 110 has a generally rectangular parallelepiped shape extending in the direction in which ions fly. In the following description, a pair of side walls of the vacuum vessel 110 facing each other in the width direction are referred to as side walls 111 and 112. The vacuum pump 120 is, for example, a turbo-molecular pump, and is attached to the outer surface of the side wall 111 of the vacuum vessel 110. The direction in which ions fly in the vacuum vessel 110 is defined as downstream, and the opposite direction is defined as upstream.

[0012] The vacuum vessel 110 includes an ionization chamber 101 located upstream and an analysis chamber 102 located downstream. For example, a liquid chromatograph (not shown) is connected to the ionization chamber 101, and a liquid sample to be measured is supplied from the liquid chromatograph. In the ionization chamber 101, the liquid sample is sprayed while being charged by, for example, an ESI probe (electrospray ionization probe) (not shown). As a result, components in the liquid sample are ionized in the ionization chamber 101. Usually, monovalent ions of each component are generated.

[0013] The analysis chamber 102 is maintained at a vacuum level (for example, 10 -2 ~10 -3 The analysis chamber 102 is maintained in a vacuum state of 100 Pa. In the analysis chamber 102, an ion lens 130, a quadrupole mass filter 140, and a detector 150 are arranged in this order from upstream to downstream. Ions generated in the ionization chamber 101 are guided to the ion lens 130 in the analysis chamber 102. The ions guided to the ion lens 130 are focused so as to fly parallel to the axis Ax, and pass through the ion lens 130.

[0014] The quadrupole mass filter 140 includes four rod electrodes 141 to 144. The rod electrodes 141 and 142 are disposed symmetrically with respect to the axis Ax, and the rod electrodes 143 and 144 are disposed symmetrically with respect to the axis Ax. The rod electrodes 141 to 144 are provided at equal angular intervals at positions spaced a distance r from the axis Ax. This forms a cylindrical space SP surrounded by the rod electrodes 141 to 144. The space SP extends in the direction of the axis Ax.

[0015] The power supply circuit 160 applies a sum voltage +(U+Vcosωt) of a DC voltage +U and a high-frequency AC voltage +Vcosωt to the rod electrodes 141 and 142. The power supply circuit 160 also applies a sum voltage -(U+Vcosωt) of a DC voltage -U and a high-frequency AC voltage -Vcosωt to the rod electrodes 143 and 144. This forms a quadrupole electric field in the space SP. Here, U is the value of the DC voltage, V is the amplitude (maximum value) of the high-frequency AC voltage, ω is the angular frequency, and t is time. The sum voltage +(U+Vcosωt) and the sum voltage -(U+Vcosωt) have a phase difference of 180° from each other.

[0016] Ions that have passed through the ion lens 130 are guided to the space SP and oscillate in the space SP according to Mathieu's equation due to the quadrupole electric field in the space SP. If the ions in the space SP oscillate unstably, the ions in the space SP cannot pass through the space SP of the quadrupole mass filter 140. Ions with a specific mass-to-charge ratio oscillate stably in the space SP and can pass through the space SP.

[0017] The detector 150 is, for example, an electron multiplier. The detector 150 detects ions that have passed through the space SP of the quadrupole mass filter 140, and outputs a detection signal indicating the detection intensity. The ground electrode in the detector 150 is connected to the vacuum vessel 110, which is maintained at ground potential, by a single connection line. The processing unit 170 includes, for example, a CPU (Central Processing Unit), and processes the detection signal output by the detector 150 to create a mass spectrum indicating the relationship between the mass-to-charge ratio of ions and the detection intensity.

[0018] (2) Fixing the detector A method for fixing the detector 150 will be described below. Fig. 2 is a schematic perspective view showing the configuration of the detector 150. As shown in Fig. 2, the detector 150 includes a base 151 for being fixed to the vacuum vessel 110. The base 151 has a flat plate shape and is disposed in a vertical position. Two notches 152 having a substantially semicircular shape are formed at an upper end of the base 151 at a predetermined interval. Two notches 152 having a substantially semicircular shape are formed at a predetermined interval at a lower end of the base 151.

[0019] Fig. 3 is a partial enlarged view showing the internal structure at the downstream end of the vacuum vessel 110. As shown in Fig. 3, the detector 150 is disposed at the downstream end of the vacuum vessel 110 (analysis chamber 102) such that the base 151 is aligned along the axis Ax. The detector 150 is fixed to the vacuum vessel 110 by attaching the base 151 to the vacuum vessel 110. In this example, the detector 150 is fixed to the vacuum vessel 110 via a mounting fixture 10 that is a part of the vacuum vessel 110.

[0020] FIG. 4 is a diagram showing the configuration of the mounting fixture 10. As shown in FIG. 4, the mounting fixture 10 has a flat base 11 extending in the vertical direction. An approximately horizontally bent portion 12 is provided at each of the upper and lower ends of the base 11. Two mounting pieces 13 that protrude downward are provided at a predetermined interval at the end of the upper bent portion 12. Two mounting pieces 13 that protrude upward are provided at a predetermined interval at the end of the lower bent portion 12. A screw hole 14 is formed in each mounting piece 13. The four screw holes 14 respectively correspond to four cutout portions 152 (FIG. 2) formed in the base 151 of the detector 150.

[0021] The base 11 is attached to the vacuum vessel 110 by a plurality of screws 15 (four in the example of FIG. 4). This fixes the mounting fixture 10 to the vacuum vessel 110. Furthermore, the detector 150 is fixed to the vacuum vessel 110 by attaching the detector 150 to the mounting fixture 10. In this example, the detector 150 is fixed to the inner surface of a side wall 112 that faces the side wall 111 of the vacuum vessel 110 to which the vacuum pump 120 (FIG. 1) is attached.

[0022] Fig. 5 is a diagram for explaining a method for fixing the detector 150. As shown in Fig. 5, in this example, the detector 150 is attached to the mounting fixture 10 using the cushioning materials 20, the spacers 30, and the pressing members 40 that correspond to the respective screw holes 14 of the mounting fixture 10. That is, in this example, the detector 150 is attached to the mounting fixture 10 by four cushioning materials 20, four spacers 30, and four pressing members 40.

[0023] The buffer material 20 is formed of, for example, a rubber material. The buffer material 20 may be formed of other materials as long as the materials have elasticity and can withstand use in a vacuum environment. The buffer material 20 has a cylindrical shape. The outer diameter r1 of the buffer material 20 is larger than the radius r2 of the notch 152 of the detector 150. A groove 21 is formed in the approximate center of the outer circumferential surface of the buffer material 20 in the axial direction. The outer diameter of the buffer material 20 at the groove 21 is slightly larger than the radius of the notch 152 of the detector 150.

[0024] The spacer 30 is made of, for example, stainless steel or aluminum. The spacer 30 may be made of other materials as long as the materials have rigidity and can withstand use in a vacuum environment. The spacer 30 is an example of a tubular member, and includes a tubular portion 31 and a flange portion 32. The tubular portion 31 has a cylindrical shape. The outer diameter of the tubular portion 31 is slightly smaller than the inner diameter of the buffer material 20. In the axial direction, the length of the tubular portion 31 is slightly smaller than the length of the buffer material 20. The flange portion 32 protrudes outward from the base end of the tubular portion 31. The outer diameter of the flange portion 32 is larger than the inner diameter of the buffer material 20.

[0025] The pressing member 40 is, for example, a male screw, and includes a threaded portion 41 and a head 42. The outer diameter of the threaded portion 41 is slightly smaller than the inner diameter of the spacer 30. In the axial direction, the length of the threaded portion 41 is greater than the length of the spacer 30. The head 42 is a substantially disk-shaped screw head, and is provided at the base end of the threaded portion 41. The outer diameter of the head 42 is greater than the inner diameter of the spacer 30.

[0026] The cylindrical portion 31 of the spacer 30 is inserted into the buffer material 20. Moreover, the threaded portion 41 of the pressing member 40 is inserted into the spacer 30 from the base end side of the spacer 30. In this case, the tip of the threaded portion 41 of the pressing member 40 protrudes from the tip of the spacer 30. In this state, the tip of the threaded portion 41 of the pressing member 40 is screwed into the corresponding screw hole 14 of the mounting fixture 10.

[0027] In this fixing method, when the pressing member 40 is tightened, the head 42 presses the flange portion 32 of the spacer 30 in the moving direction of the pressing member 40. Therefore, the cushioning material 20 is held in a crushed state between the mounting piece 13 of the mounting fixture 10 and the flange portion 32. Furthermore, the tip of the tubular portion 31 of the spacer 30 abuts against the mounting piece 13, thereby restricting the amount of crushing of the cushioning material 20 to a constant value. In this way, the spacer 30 functions as a crushing amount restriction mechanism that restricts the amount of crushing of the cushioning material 20 by the pressing member 40.

[0028] Each pressing member 40, through which the buffer materials 20 and the spacers 30 have been inserted, is screwed into the corresponding screw holes 14 of the mounting fixture 10. In this way, the two buffer materials 20 are attached to the two upper mounting pieces 13 of the mounting fixture 10, respectively. In addition, the two buffer materials 20 are attached to the two lower mounting pieces 13 of the mounting fixture 10, respectively.

[0029] The two upper notches 152 formed in the base 151 of the detector 150 are fitted into the grooves 21 of the two upper cushioning materials 20, respectively. The two lower notches 152 formed in the base 151 of the detector 150 are fitted into the grooves 21 of the two lower cushioning materials 20, respectively. In this case, the base 151 is sandwiched between the two upper cushioning materials 20 and the two lower cushioning materials 20. This fixes the detector 150 to the vacuum vessel 110.

[0030] (3) Effects In the mass spectrometer 100 according to this embodiment, a plurality of cushioning materials 20 are pressed against a vacuum vessel 110 used for mass analysis of a sample by a plurality of pressing members 40. A detector 150 for detecting a sample to be analyzed is held by the plurality of cushioning materials 20. Therefore, even if vibrations caused by the vacuum pump 120 are transmitted to the vacuum vessel 110, the vibrations are damped by the cushioning materials 20. This prevents large vibrations from being transmitted to the detector 150 or a cable (not shown) connected to the detector 150.

[0031] Moreover, the amount of squeezing of the buffer material 20 by each pressing member 40 is regulated by the corresponding spacer 30. In this case, the magnitude of vibration transmitted to the detector 150 or the cable connected to the detector 150 is uniform and does not vary depending on the worker installing the vacuum pump 120. As a result, the effect of the vibration of the vacuum pump 120 on mass spectrometry can be reduced.

[0032] The pressing member 40 is screwed into the screw hole 14 of the mounting fixture 10 of the vacuum vessel 110 with the cylindrical spacer 30 and the cylindrical cushioning material 20 inserted therethrough. Therefore, the amount of crushing of the cushioning material 20 by the pressing member 40 can be regulated with a simple configuration. In addition, since the pressing member 40 is attached to the inner surface of the side wall 112 opposite to the side wall 111 to which the vacuum pump 120 is attached, the vibration transmitted from the vacuum pump 120 to the detector 150 can be further reduced.

[0033] The detector 150 is sandwiched between the two upper buffer materials 20 and the two lower buffer materials 20. Therefore, the detector 150 can be held more reliably. Here, each notch 152 of the base 151 of the detector 150 comes into contact with the corresponding groove 21 of the buffer material 20. In this case, the detector 150 can be held more stably. In addition, since the detector 150 is attached to the inner surface of the side wall 112 of the vacuum vessel 110 via the mounting fixture 10, the degree of freedom in arranging the detector 150 inside the vacuum vessel 110 is improved.

[0034] (4) Variations In the present embodiment, the spacer 30 is provided as a crushing amount regulating mechanism that regulates the amount of crushing of the cushioning material 20 by the pressing member 40, but the embodiment is not limited thereto. When another crushing amount regulating mechanism is provided, the spacer 30 does not have to be provided.

[0035] Fig. 6 is a diagram for explaining a method of fixing the detector 150 in the first modified example. As shown in Fig. 6, in the first modified example, the screw holes 14 corresponding to the pressing members 40 are not through holes but bottomed holes having a bottom portion 14a. Also, the spacer 30 is not provided.

[0036] In this example, when the pressing member 40 is tightened, the head 42 of the pressing member 40 presses the cushioning material 20 in the moving direction of the pressing member 40. Therefore, the cushioning material 20 is held in a crushed state between the mounting piece 13 of the mounting fixture 10 and the head 42. Furthermore, the tip of the threaded portion 41 of the pressing member 40 abuts against the bottom 14a of the screw hole 14, thereby restricting the amount of crushing of the cushioning material 20 to a constant value. Therefore, the bottom 14a of the screw hole 14 functions as a crushing amount restriction mechanism.

[0037] 7 is a diagram for explaining a method of fixing the detector 150 in the second modified example. As shown in FIG. 7, the pressing member 40 is a shoulder screw, and includes a cylindrical stepped portion 43 between the threaded portion 41 and the head portion 42. In addition, the spacer 30 is not provided. The outer diameter of the stepped portion 43 is larger than the outer diameter of the threaded portion 41 and slightly smaller than the inner diameter of the buffer material 20. In the axial direction, the length of the stepped portion 43 is slightly smaller than the length of the buffer material 20.

[0038] The threaded portion 41 protrudes from the tip of the stepped portion 43. The head 42 is provided at the base end of the stepped portion 43. The protruding length of the threaded portion 41 is smaller than the length of the stepped portion 43 in the axial direction. Other dimensional characteristics of the threaded portion 41 and the stepped portion 43 are similar to those of the threaded portion 41 and the stepped portion 43 in FIG. 5, respectively.

[0039] In this example, as the pressing member 40 is tightened, the head 42 of the pressing member 40 presses the cushioning material 20 in the direction of travel of the pressing member 40. Therefore, the cushioning material 20 is held in a crushed state between the mounting piece 13 of the mounting fixture 10 and the head 42. Furthermore, as the tip of the stepped portion 43 of the pressing member 40 abuts against the mounting piece 13, the amount of crushing of the cushioning material 20 is regulated to a constant value. Therefore, the stepped portion 43 of the pressing member 40 functions as a crushing amount regulating mechanism.

[0040] (5) Other embodiments (a) In the above embodiment, the detector 150 is fixed to the side wall of the vacuum vessel 110 via the fixture 10, but the embodiment is not limited to this. When a screw hole similar to the screw hole 14 of the fixture 10 is provided in the side wall of the vacuum vessel 110, the detector 150 may be fixed directly to the side wall of the vacuum vessel 110 without using the fixture 10.

[0041] (b) In the above embodiment, the detector 150 is fixed to the side wall 112 opposite the side wall 111 to which the vacuum pump 120 is attached, but the embodiment is not limited to this. The detector 150 may be fixed to a side wall different from the side wall 112, or may be fixed to the side wall 111 to which the vacuum pump 120 is attached.

[0042] (c) In the above embodiment, the detector 150 is sandwiched between two upper cushioning materials 20 and two lower cushioning materials 20, but the embodiment is not limited to this. The detector 150 may be sandwiched between two cushioning materials 20. The two cushioning materials 20 that support the detector 150 may be arranged to be aligned in the vertical direction, or may be arranged to be aligned in the horizontal direction. The detector 150 may also be held by one cushioning material 20.

[0043] (d) In the above embodiment, the base 151 of the detector 150 has the notch 152 formed therein for contacting the buffer material 20, but the embodiment is not limited to this. The base 151 does not necessarily have to have the notch 152 formed therein.

[0044] (e) In the above embodiment, the groove 21 for contacting the base 151 of the detector 150 is formed in the buffer material 20, but the embodiment is not limited to this. The buffer material 20 does not necessarily have to have the groove 21 formed therein.

[0045] (6) Description It will be appreciated by those skilled in the art that the above exemplary embodiments are illustrative of the following aspects.

[0046] (Item 1) A mass spectrometer according to one aspect of the present invention comprises: a vacuum vessel used for mass spectrometry of a sample; a detector for detecting a sample to be analyzed; A cushioning material for holding the detector; a pressing member that presses the cushioning material against the vacuum container; The shock absorber may further include a crushing amount regulating mechanism that regulates the amount of crushing of the cushioning material by the pressing member.

[0047] In this mass spectrometer, the cushioning material is pressed against the vacuum vessel used for mass spectrometry of the sample by the pressing member, and the detector for detecting the sample to be analyzed is held by the cushioning material. Therefore, even if vibrations caused by the vacuum pump are transmitted to the vacuum vessel, the vibrations are attenuated by the cushioning material. This prevents large vibrations from being transmitted to the detector or the cable connected to the detector.

[0048] In addition, because the amount of compression of the cushioning material by the pressing member is regulated by the compression amount regulating mechanism, the magnitude of vibration transmitted to the detector or the cable connected to the detector is uniform regardless of the person installing the vacuum pump, thereby reducing the effect of vacuum pump vibration on mass spectrometry.

[0049] (2) In the mass spectrometer according to (1), The crushing amount regulating mechanism includes a cylindrical member, The pressing member may include a screw, and may press the cushioning material against the vacuum container by being screwed into the vacuum container with the cylindrical member and the cushioning material inserted therethrough.

[0050] In this case, the amount of crushing of the cushioning material by the pressing member can be regulated with a simple structure.

[0051] (Item 3) In the mass spectrometer according to item 1 or 2, the vacuum vessel includes a first sidewall and a second sidewall opposed to each other; a vacuum pump for creating a vacuum inside the vacuum vessel is attached to an outer surface of the first side wall; The pressing member may be attached to an inner surface of the second side wall to press the cushioning material.

[0052] In this case, the vibration transmitted from the vacuum pump to the detector can be further reduced.

[0053] (Item 4) In the mass spectrometer according to any one of items 1 to 3, The cushioning material includes a first cushioning material and a second cushioning material, the pressing member includes a first pressing member that presses the first cushioning material against the vacuum container and a second pressing member that presses the second cushioning material against the vacuum container; the crushing amount regulating mechanism further includes a first crushing amount regulating mechanism that regulates an amount of crushing of the first cushioning material by the first pressing member, and a second crushing amount regulating mechanism that regulates an amount of crushing of the second cushioning material by the second pressing member, The detector may be sandwiched between the first buffer material and the second buffer material.

[0054] In this case, the detector can be held more reliably by the first buffer material and the second buffer material.

[0055] (Item 5) In the mass spectrometer according to item 4, The first cushioning material and the second cushioning material may be arranged side by side in a vertical direction. In this case, the detector can be held more securely.

[0056] (Item 6) In the mass spectrometer according to item 4 or 5, The detector may include a base having a first cutout and a second cutout formed therein, the first cutout and the second cutout abutting against the first buffer material and the second buffer material, respectively.

[0057] In this case, the detector can be held more stably.

[0058] (Item 7) In the mass spectrometer according to item 6, The first buffer material has a first groove portion that comes into contact with the first cutout portion, The second cushioning material may have a second groove formed therein that abuts against the second cutout.

[0059] In this case, the detector can be held more stably.

[0060] (Item 8) In the mass spectrometer according to any one of items 1 to 7, the vacuum vessel includes a mounting fixture to which the pressing member is attached, The pressing member may be attached to the mounting fixture to press the cushioning material.

[0061] In this case, the degree of freedom in arranging the detector is improved.

Claims

1. a vacuum vessel used for mass spectrometry of a sample; a detector for detecting a sample to be analyzed; A cushioning material for holding the detector; a pressing member that presses the cushioning material against the vacuum container; a crushing amount regulating mechanism that regulates the amount of crushing of the cushioning material by the pressing member, the vacuum vessel includes a first sidewall and a second sidewall opposed to each other; a vacuum pump for creating a vacuum inside the vacuum vessel is attached to an outer surface of the first side wall; The pressing member is attached to an inner surface of the second side wall to press the buffer material.

2. The crushing amount regulating mechanism includes a cylindrical member, 2. The mass spectrometer according to claim 1, wherein the pressing member includes a screw, and presses the buffer material against the vacuum vessel by being screwed into the vacuum vessel with the cylindrical member and the buffer material inserted therethrough.

3. A vacuum vessel for use in mass spectrometry of a sample; a detector for detecting a sample to be analyzed; A cushioning material for holding the detector; a pressing member that presses the cushioning material against the vacuum container; a crushing amount regulating mechanism that regulates the amount of crushing of the cushioning material by the pressing member, the cushioning material includes a first cushioning material and a second cushioning material; the pressing member includes a first pressing member that presses the first cushioning material against the vacuum container, and a second pressing member that presses the second cushioning material against the vacuum container, the crushing amount regulating mechanism further includes a first crushing amount regulating mechanism that regulates an amount of crushing of the first cushioning material by the first pressing member, and a second crushing amount regulating mechanism that regulates an amount of crushing of the second cushioning material by the second pressing member, the detector is sandwiched between the first buffer material and the second buffer material, and includes a base having a first notch and a second notch that abut against the first buffer material and the second buffer material, respectively.

4. The mass spectrometer according to claim 3 , wherein the first buffer material and the second buffer material are arranged so as to be aligned vertically.

5. The first buffer material has a first groove portion that comes into contact with the first cutout portion, 5. The mass spectrometer according to claim 3, wherein the second buffer material has a second groove formed therein and contacts the second cutout.

6. the vacuum vessel includes a mounting fixture to which the pressing member is attached, 5. The mass spectrometer according to claim 1, wherein the pressing member presses the buffer material by being attached to the mounting fixture.

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