JP2021162375A - NMR measurement probe - Google Patents

Abstract

To suppress acoustic ringing, which is a surface acoustic wave transmitted through a block main body, in a cooled NMR measurement probe.SOLUTION: A detection module 24 includes a block main body 46, a coil 54, and two damping plates 86 and 88. The block main body 46 functions as a thermal conductor and a coil support. The damping plates 86 and 88 are made of a damping material that exhibits anti-ferromagnetism and damping action at extremely low temperatures. Acoustic ringing transmitted through the block main body 46 is suppressed by the damping plates 86 and 88. Screws 89 and 90 and a support member 58 are also made of the damping material.SELECTED DRAWING: Figure 3

Description

The present invention relates to an NMR (nuclear magnetic resonance) measuring probe, and more particularly to a cooling type NMR measuring probe.

An NMR probe is used for NMR measurement. Patent Document 1 discloses a cooled NMR measurement probe for measuring a solid sample. The NMR measurement probe has a detection module (which can also be called a detection block). The detection module has a block body having a through hole and a coil formed on the inner surface of the through hole. The block body is made of an insulating material that has good thermal conductivity at extremely low temperatures and does not have magnetism. The block body is connected to the heat exchanger via a support member. Refrigerants such as helium gas are circulating in the heat exchanger. The support member and the block body function as heat conductors, and the temperature of the coil is maintained at an extremely low temperature.

In the NMR measurement probe, the sample tube is arranged so as to pass through the inside of the coil. Specifically, the sample tube has a posture tilted by a predetermined angle (so-called magic angle) with respect to the direction of the static magnetic field, and the sample tube is rotationally driven while maintaining the tilted posture (magic-angle spinning method). The detection module is located in vacuum space, while the sample tube is located in atmospheric space. At the time of NMR measurement, the solid sample in the sample tube is irradiated with electromagnetic waves from the coil. As a result, the NMR generated in the solid sample is detected by the coil. By cooling the coil (and other electrical components), the NMR signal can be detected with high sensitivity. The cooled NMR measurement probe is also called a cryocoil MAS probe.

In addition, Patent Document 2 describes a nuclear magnetic resonance imaging apparatus including a vibration damping member. Patent Document 3 does not recognize a member corresponding to a cooling type detection block provided with a coil.

Japanese Unexamined Patent Publication No. 2014-41104 International Publication No. 2006/062028 Japanese Patent No. 2849698

When electromagnetic waves are irradiated during NMR measurement, surface acoustic waves are generated on the surface of conductors (particularly coils). Surface acoustic waves are caused by an electric field generated by irradiation of an electromagnetic field, which is called acoustic ringing. In particular, acoustic ringing tends to be a problem in a high magnetic field environment where the carrier frequency is low (for example, 100 MHz or less) and the magnetic flux density is several tesla or more.

When acoustic ringing enters the observation period of the received signal, an artifact occurs in the NMR spectrum. If the start time of the observation period of the received signal is delayed in order to avoid acoustic ringing, that is, if the dead time provided after transmission is lengthened, the received signal component immediately after transmission cannot be observed and the sensitivity decreases. , It becomes impossible to observe the important phenomenon immediately after transmission.

In an NMR probe with a cooled detection module, the coil is in close contact with the block body, or the coil is integrated with the block body. The block body is made of an insulating material having good thermal conductivity and is cooled, and the block body is usually very hard. When vibration is transmitted from the coil to the block body, the vibration is difficult to attenuate. Moreover, when the block body is supported by the cantilever method, vibration tends to stay in the block body. When using a cooled NMR probe, acoustic ringing becomes a major problem.

The present invention is to suppress acoustic ringing transmitted to the block body in the NMR measurement probe.

The NMR measurement probe according to the present invention is in close contact with the block body, the coil for NMR detection provided on the block body and cooled via the block body, and the surface of the block body, and the transmission operation of the coil. It is characterized by including a vibration damping member made of a material that suppresses acoustic ringing that is later transmitted to the block body.

According to the present invention, in the NMR measurement probe, acoustic ringing transmitted to the block body can be suppressed.

It is a schematic diagram which shows the NMR measurement system which includes the NMR measurement probe which concerns on embodiment. It is sectional drawing of the NMR measurement probe which concerns on embodiment. It is a perspective view which shows the detection module and the member around it. It is a perspective view which shows the 1st Embodiment of a detection module. It is a perspective view which shows the 2nd Embodiment of the detection module. It is sectional drawing which shows the 2nd Example of a detection module. It is a perspective view which shows the 1st modification of a detection module. It is a perspective view which shows the 2nd modification of a detection module. It is a figure which shows three detection modules which were the subject of an experiment. It is a figure which shows the experimental result. It is a figure which shows the acoustic ringing schematically.

Hereinafter, embodiments will be described with reference to the drawings.

(1) Outline of Embodiment The NMR measurement probe according to the embodiment includes a block body, a coil for NMR detection, and a vibration damping member. The coil is formed on the block body and is cooled via the block body. The damping member is made of a material that adheres to the surface of the block body and suppresses acoustic ringing transmitted to the block body after the coil transmission operation.

Since the damping member is in close contact with the surface of the block body, the acoustic ringing, which is a surface acoustic wave propagating in the block body, can be suppressed by the damping member. Even if the blank period is shortened, artifacts due to acoustic ringing are less likely to occur.

The material that suppresses acoustic ringing is, of course, a material that exerts a higher damping effect than the material that constitutes the block body, and from another point of view, it is more than copper, which is generally used as a heat conductive material. Is also a material that exerts a high damping effect. As a material that suppresses acoustic ringing, a material that exhibits diamagnetism or antiferromagnetism and has a logarithmic decrement of 0.01 or more at the cooling temperature of the vibration damping member can be used. Alternatively, as a material for suppressing acoustic ringing, a twin crystal type damping material containing manganese as a main component can be used.

In the embodiment, the block body extends in the vertical direction. The block body has a tip portion existing on one side in the vertical direction and a base end portion existing on the other side in the vertical direction. The coil is provided at the tip. The base end is supported by a support member.

The detection module is composed of the block body, the coil, and the vibration damping member. The detection module is conceived as a detection block or a detection assembly. Generally, the detection module is supported in a cantilever manner. The above-mentioned vertical direction is a longitudinal direction and an extension direction of the block body.

In the embodiment, the vibration damping member is provided on the surface of the base end portion while being separated from the tip end portion. When the damping member exhibits paramagnetism even slightly (for example, when it exhibits paramagnetism due to residual magnetization), if such a damping member is placed near the coil, the damping member disturbs the magnetic field and adversely affects NMR detection. To exert. If the vibration damping member is arranged apart from the coil, specifically, if the vibration damping member is arranged at the base end portion, the problem caused by the magnetism of the vibration damping member can be solved or alleviated. If the vibration damping member has no paramagnetism at all, the vibration damping member may be provided at the tip end, that is, in the vicinity of the coil.

In the embodiment, the base end portion has a first surface and a second surface having a first width in the horizontal direction orthogonal to the vertical direction, and a second surface smaller than the first width in the thickness direction orthogonal to the vertical direction and the horizontal direction. It has a third surface and a fourth surface having a width. The vibration damping member includes a first vibration damping plate in close contact with the first surface and a second vibration damping plate in close contact with the second surface.

If two damping plates are provided on two relatively wide surfaces at the base end, acoustic ringing can be effectively suppressed. In addition to these damping plates, damping plates may be provided on the other two planes (third plane and fourth plane) at the base end, respectively. A cylindrical vibration damping plate surrounding the rod-shaped block body may be provided.

In embodiments, the thickness direction is parallel to the central axis of the coil. Electrode layers are provided on two surfaces of the block body that are orthogonal to each other in the thickness direction. When such a configuration is adopted, it is considered that acoustic ringing is easily transmitted to those two planes (two planes including the first plane and the second plane of the base end portion). If the first damping plate is provided on the first plane and the second damping plate is provided on the second plane, the acoustic ringing transmitted through the block body can be effectively suppressed.

In the embodiment, a plurality of screws are provided so as to penetrate the laminate composed of the first vibration damping plate, the base end portion and the second vibration damping plate. The laminate is fixed to the support member by the plurality of screws. According to this configuration, the two damping plates can be attached to the base end portion together with the attachment of the detection module to the support member. Even when the two damping plates are attached to the base end portion by an adhesive, if the two damping plates are further fixed with a plurality of screws, the first plane and the second plane at the base end portion can be obtained. On the other hand, the first vibration damping plate and the second vibration damping plate can be reliably brought into close contact with each other. In particular, in the cooling type detection module, the adhesive action may be reduced due to heat shrinkage, so it is of great significance to adopt the above configuration.

In the embodiment, the plurality of screws are each composed of a material that suppresses acoustic ringing. According to this configuration, acoustic ringing can be suppressed more effectively. In embodiments, the support member is constructed of a material that suppresses acoustic ringing. According to this configuration, acoustic ringing can be suppressed more effectively. In particular, it is possible to prevent the propagation of acoustic ringing to other members (electronic parts, etc.).

(2) Details of the Embodiment FIG. 1 shows an NMR measurement system according to the embodiment. The illustrated NMR measurement system 10 includes a spectrometer (not shown), a static magnetic field generator 12, an NMR measurement probe 14, a cooling device 16, and a circulation device 18. The spectrometer has a transmission circuit, a reception circuit, an NMR spectrum generation circuit, and the like.

A static magnetic field is generated by the static magnetic field generator 12. The static magnetic field generator 12 has a bore as a hollow hole. The NMR measurement probe 14 has an insertion portion 20 to be inserted into the bore and a base portion 22 connected to the lower end of the insertion portion. The NMR measurement probe 14 has a partition wall 23 as a housing. The inside of the partition wall 23 is a vacuum space.

A detection module 24 as a detection block or a detection assembly is provided in the insertion portion 20. The detection module 24 has a coil for detecting an NMR signal. The sample tube 26 passes through the inside of the coil. A solid sample is housed inside the sample tube 26. The solid sample may be a powder. The first detection circuit is composed of a coil, a variable capacitor, and the like.

A first heat exchanger 32 is provided in the insertion portion 20. Refrigerant circulates in the first heat exchanger 32. Specifically, the refrigerant is helium gas cooled to an extremely low temperature. Liquid helium, liquid nitrogen, nitrogen gas and the like may be used as the refrigerant. The first heat exchanger 32 cools the first detection circuit. In particular, the entire detection module 24 including the coil is cooled. By cooling electrical components such as coils, thermal noise can be reduced and the SN ratio can be increased. In other words, the NMR detection sensitivity can be increased.

The sample tube 26 has a posture tilted by a predetermined angle (so-called magic angle) with respect to the static magnetic field direction (vertical direction in FIG. 1), and is rotationally driven by the rotation mechanism 28 in that posture. The rotation mechanism 28 is also called a spinner. The rotation mechanism 28 is housed in the shield 30. The coil is arranged in a vacuum space, and the temperature of the coil is, for example, 20 K or less. On the other hand, the sample tube is arranged in the outside world (air space) under atmospheric pressure, and the temperature of the outside world is room temperature.

A second detection circuit 34 is provided in the base 22. The second detection circuit 34 includes, for example, a preamplifier, a duplexer, and the like. A second heat exchanger 36 is connected to the second detection circuit 34. The refrigerant that has passed through the first heat exchanger 32 circulates in the second heat exchanger 36. The second detection circuit 34 is cooled by the second heat exchanger 36. A pipe for circulating the refrigerant is provided in the partition wall 23.

A transfer tube 38 is provided between the cooling device 16 and the NMR measurement probe 14. A feed pipe and a return pipe are provided therein. The return pipe extends through the cooling device 16 to the circulation device 18. The circulation device 18 has a pump 40 for circulating a refrigerant. The refrigerant sent out from the pump 40 is cooled to an extremely low temperature by the cooling equipment 42 in the cooling device 16. The cooled refrigerant is transported to the NMR measurement probe 14 through the feed pipe. The cooling equipment 42 includes a refrigerator, a cold bench, and the like.

FIG. 2 shows the periphery of the upper part of the insertion portion. A stage 44 is connected to the first heat exchanger 32, and a plurality of electric components 60 and 62 are mounted on the stage. The plurality of electrical components 60 and 62 are, for example, a plurality of variable capacitors. The first detection circuit is composed of the coil 54 and the plurality of electric components 60 and 62. The first heat exchanger 32 is for cooling the first detection circuit. The detection module 24 is connected to the first heat exchanger 32 via the support member 58.

The detection module 24 includes a block body 46, a coil 54, and vibration damping members (vibration damping plates 86, 88 described later). The block body 46 extends in the vertical direction (longitudinal direction) and has a tip portion 48 and a base end portion 50 arranged in the vertical direction. An opening 52 as a through hole is formed in the tip portion 48. A coil 54 is formed on the cylindrical inner surface of the opening 52. The coil 54 is a strip-shaped and film-shaped electrode layer having a solenoid shape. The electrode layer is formed by plating, for example, and the material constituting the electrode layer is, for example, copper.

In the illustrated first embodiment, the block body 46 is made of an insulating material having good thermal conductivity at an extremely low temperature and having no magnetism, and is particularly made of a single seamless member. .. Specifically, it is composed of a single crystal of sapphire. The block body may be composed of a single crystal of quartz. The block body 46 functions as a coil support and a heat conductor.

The sample tube 26 passes through the opening 52 in a non-contact manner. Specifically, a cylindrical cavity 23B is formed in the upper portion 23A of the partition wall 23. A sample tube is inserted into the cavity 23B in a non-contact manner. The inside of the partition wall 23 is a vacuum space, and the inside of the cavity 23B is an atmospheric space. The rotation mechanism 28 rotationally drives the sample tube 26 having an inclined posture. Note that FIG. 2 shows only the outer shape of the rotation mechanism 28.

Two damping plates 86 and 88 as damping members are joined to the two surfaces of the base end portion 50 in close contact with each other. The vibration damping plates 86 and 88 each have a flat plate shape, and are made of a material that suppresses acoustic ringing propagating through the block body 46. In the embodiment, M2052 alloy is adopted as the material thereof. The M2052 alloy is an alloy containing Mn as a main component, and contains Cu, Ni, and Fe in addition to Mn. The M2052 alloy has a twin structure and exerts an action of converting mechanical energy into thermal energy (see Patent Document 3). The material exhibits good damping properties at the temperature of liquid helium or helium gas, specifically at 4K to 20K. The M2052 alloy basically exhibits antiferromagnetism in the temperature range of 4K to 20K shown on the left, and exhibits a logarithmic decrement of 0.01 or more. Two damping plates 86, 88 made of such a material are joined to the base end portion 50.

Even if the M2052 alloy has antiferromagnetism as a whole, the material has a slight paramagnetism, and specifically, the residual magnetization in the material exhibits paramagnetism. Therefore, in the first embodiment shown in FIG. 2, two vibration damping plates 86 and 88 made of M2052 alloy are arranged at positions separated from the coil 54. Specifically, the two damping plates 86 and 88 are arranged at positions separated from the center of the magnetic field (center of the coil) by 20 mm or more.

As a material constituting the vibration damping member, a material other than the M2052 alloy may be used. For example, the vibration damping member may be constructed by using a material exhibiting diamagnetism or antiferromagnetism and having a logarithmic decrement of 0.01 or more at an extremely low temperature. In that case, ^{a material having a residual magnetic susceptibility of 20 × 10-6} [emu / g / Oe] or less can be used.

In the embodiment, as will be described later, a laminate composed of two vibration damping plates 86, 88 and a base end portion 50 is attached to the support member 58 by two screws penetrating the laminate. The two screws and the support member 58 are also made of the above material, that is, the M2052 alloy. As a result, the acoustic ringing reducing effect is further enhanced.

Both ends of the coil 54 are electrically connected to two electrode layers formed on the surface of the block body 46. Each electrode layer is a copper film formed by plating. The two electrode layers are connected to electrical components 60, 62, etc. via two copper foils (two copper ribbons) and two leads (two copper wires). Clamps 56 are provided on one side and the other side of the block body 46 to electrically and mechanically connect the electrode layer and the copper foil. The clamp 56 exerts a holding action. The central axis of the coil 54 and the central axis of the detection module 24 are orthogonal to each other. Reference numeral 64 indicates a radiation shield.

FIG. 3 shows the detection module 24 and its surroundings. The y direction is the vertical direction (longitudinal direction, extension direction), the x direction is the horizontal direction, and the z direction is the thickness direction. The three directions are orthogonal.

As described above, the detection module 24 includes a block body 46 extending in the vertical direction, a coil 54 formed on the block body 46, and two damping plates 86 and 88. The block body 46 is made of an insulating material having good thermal conductivity even at extremely low temperatures, specifically, as described above, a single crystal of sapphire.

The block body 46 has a tip end portion 48 and a base end portion 50. The tip portion 48 is enlarged in the thickness direction as compared with the base end portion 50. An opening 52 as a through hole is formed in the tip portion 48, and a solenoid-shaped coil 54 is formed on the inner surface thereof. The central axis of the coil 54 is parallel to the thickness direction. A pair of electrode layers are connected to both ends of the coil, but in FIG. 3, only one of the electrode layers 70 is shown.

The base end portion 50 has a plate-like shape. Two damping plates 86 and 88 are attached to the two wide flat surfaces at the base end portion 50 in close contact with each other. Each of the damping plates 86 and 88 has a trapezoidal shape when viewed from the z direction. The shape is the result of devising a contact area as wide as possible while avoiding physical interference with other members. Therefore, the shape is only an example. The material constituting each of the damping plates 86 and 88 is the M2052 alloy as described above. Its thickness is, for example, in the range of 0.5 to 2 mm, for example, 1 mm. The size of each vibration damping plate 86,88 in the x direction is, for example, 10 mm, and the size (maximum value) of each vibration damping plate 86,88 in the y direction is, for example, 15 mm. Each numerical value is an example. A vibration damping plate composed of a plurality of laminated layers may be used.

The vibration damping plate 86, the base end portion 50, and the vibration damping plate 88 are laminated in the z direction, thereby forming a laminated body. The laminate is fixed to the support member 58 by two screws 89 and 90. The support member 58 has an inclined portion 58A and a horizontal portion 58B in the illustrated example. The laminated body is fixed to the end face of the inclined portion 58A. The horizontal portion 58B is fixed to the ceiling wall of the first heat exchanger by two screws (not shown). The support member 58 is also made of M2052 alloy as described above. The screw diameter of the screws 89 and 90 is about 3 mm. The length of the screws 89, 90 is in the range of approximately 10 to 20 mm. Each numerical value in the detection module is determined according to the outer diameter of the sample tube. The outer diameter of the sample tube is, for example, 4 mm.

The arithmetic average roughness Ra of each surface is set to less than 0.8 in order to reduce the voids generated between the surface of the block body 46 and the surfaces of the damping plates 86 and 88 and to increase the degree of adhesion between the surfaces. Is desirable. It is particularly desirable that the arithmetic mean roughness Ra of each surface is less than 0.1.

There is an intermediate portion between the tip end portion 48 and the base end portion 50. However, it is also possible to understand that the tip end portion 48 and the base end portion 50 are connected. In that case, the base end portion 50 includes the intermediate portion. In the illustrated configuration example, the tip 48 is enlarged in the z direction, and the xy cross section of the tip 48 is polygonal. The plate-shaped portion connected to the tip portion 48 is the intermediate portion.

A clamp 56 is attached to the intermediate portion. The clamp 56 has a first clip member 72 and a second clip member 74, and also has two screws 76, 78 connecting them. The intermediate portion of the block body 46 is sandwiched between the first clip member 72 and the second clip member 74. Both the first clip member 72 and the second clip member 74 are made of a non-magnetic insulating material. The two screws 76 and 78 are also made of a non-magnetic insulating material.

By sandwiching the intermediate portion between the first clip member 72 and the second clip member 74, the electrode layer 70 and the copper foil 80 are physically bonded to each other on one side of the intermediate portion. The electrode layer and the copper foil 82 are also physically bonded to each other on the opposite side of the intermediate portion. A lead 84 made of copper is connected to the copper foil 80. A lead 85 made of copper is connected to the copper foil 82. In FIG. 3, two leads 84 and 85 are partially drawn.

After the transmission operation of the coil 54, acoustic ringing occurs in the coil 54 and the like. It propagates through the block body 46. The acoustic ringing propagating through the block body 46 is absorbed by the two damping plates 86 and 88 that are in close contact with the block body 46. That is, the acoustic ringing is prevented from remaining for a long time, and the amplitude of the acoustic ringing itself is suppressed. As a result, the time lag that should be provided immediately after transmission can be shortened. If the time lag becomes short, it becomes possible to observe more received signals, particularly received signals generated immediately after transmission.

The block body 46 is made of a very hard material, yet it is cooled to a cryogenic temperature. The detection module 24 is supported in a cantilever manner. Vibration is likely to occur in the detection module 24, and the generated vibration is difficult to escape to the outside world. The two leads 84, 85 are in contact with the detection module 24 via the flexible copper foils 80, 82, and these members do not exert a significant damping effect.

According to the configuration according to the embodiment, it is possible to suppress acoustic ringing in the detection module 24 itself by the two damping plates 86 and 88 made of the damping material. Since the two screws 89, 90 and the support member 58 are also made of the damping material, the acoustic ringing can be suppressed more effectively, and at the same time, the acoustic ringing is prevented from being transmitted to the probe lower member.

FIG. 4 shows the detection module 24 according to the first embodiment. The clamps mentioned above are not shown. The detection module 24 has a base end portion 50, and the base end portion 50 has a relatively wide first surface 50a and a second surface 50b, and a relatively narrow third surface. It has 50c and a fourth surface 50d. The first surface 50a and the second surface 50b are orthogonal to the z direction, and the third surface 50c and the fourth surface 50d are orthogonal to the x direction. In the embodiment, among those surfaces, vibration damping plates 86 and 88 are provided on the first surface 50a and the second surface 50b.

The central axis of the coil is parallel to the z direction, and two electrode layers are formed on two surfaces (two planes including the first surface 50a and the second surface 50b) orthogonal to the z direction in the block body 46. There is. In such a configuration, it is considered that acoustic ringing is likely to propagate on two surfaces orthogonal to the z direction. By providing damping plates 86 and 88 on those surfaces, it is possible to suppress acoustic ringing more effectively. Further, a vibration damping plate may be provided on the third surface 50c and the fourth surface 50d, or a vibration damping plate may be provided on the lower surface.

FIG. 5 shows the detection module 92 according to the second embodiment. The detection module 92 has a block body 94. The block body 94 is composed of a first portion 96 and a second portion 98 that are continuously connected in the vertical direction. The first portion 96 corresponds to the tip portion, which has the first engaging portion 100. The second portion 98 corresponds to a proximal end portion and an intermediate portion, which has a second engaging portion 102. The first engaging portion 100 and the second engaging portion 102 are engaged to form a connecting portion as an engaging portion. The connecting portion is clamped. In FIG. 5, the portion surrounded by the clamp is indicated by the broken line 103.

FIG. 6 shows a cross section of the detection module 92 according to the second embodiment. As described above, the first portion 96 has a first engaging portion 100 and the second portion 98 has a second engaging portion 102. Specifically, the first engaging portion 100 is composed of a first convex portion and a first step adjacent thereto, and the second engaging portion 102 is formed of a second convex portion and a second step adjacent thereto. It is composed. The first convex portion is fitted in the second step, and the second convex portion is fitted in the second step. The first engaging portion 100 has a tip surface 104, a side surface 106, and a retracting surface 108. The second engaging portion 102 has a tip surface 109, a side surface 110, and a retracting surface 112. The side surface 106 and the side surface 110 are in close contact with each other. In order to improve the thermal conductivity, at least the side surfaces 106 and 110 are mirror-finished. In the illustrated configuration example, the tip surface 104 and the retracting surface 112 are joined, and the retracting surface 108 and the tip surface 109 are joined. Mirror processing may be applied to those surfaces.

W1 indicates the width of the side surfaces 106 and 110 in the y direction. W2 indicates the width in the y direction covered by the clamping action. In the illustrated configuration example, W2 is larger than W1, but they may be the same, or W2 may be smaller than W1.

In the second embodiment, the block body is composed of two separate parts. Therefore, the frequency (resonance frequency) of the acoustic ringing that occurs in the first portion 96 including the coil naturally increases. In general, the higher the frequency, the greater the amount of vibration damping over time. In the case of the cantilever method, the resonance frequency becomes low and the acoustic ringing tends to remain, but according to the second embodiment, the frequency manipulation can promote the natural attenuation of the acoustic ringing. At the same time, the remaining acoustic ringing is suppressed by the two damping plates.

FIG. 7 shows the detection module 114 according to the first modification. In the block body 116, two damping plates 122 and 124 are adhered to the base end portion 120 by an adhesive. There are a plurality of surfaces at the tip 118. A damping piece group (vibration damping plate group) 126 is attached to all or part of them. The damping piece group 126 is composed of a plurality of damping pieces 126a to 126g. The individual damping pieces 126a to 126g are each composed of M2052 alloy. If the first modification is adopted, the vibration damping piece group 126 may be peeled off from the block body 116 due to heat shrinkage due to cooling. In such a case, the second modification described below may be adopted.

FIG. 8 shows the detection module 114A according to the second modification. A plurality of main damping pieces in the damping piece group 126 are pressed by the clips 128. The clip 128 exerts an action of pressing a plurality of vibration damping pieces toward the tip portion side by an elastic action. A plurality of damping pieces not covered with the clip 128 may also be pressed by another clip or the like.

The first modification and the second modification shown in FIGS. 7 and 8 can be adopted when the vibration damping member does not have residual magnetization. When the damping member exhibits paramagnetism that cannot be ignored, it is better to dispose the damping member away from the coil. For example, as described above, the vibration damping member is arranged at the base end portion.

Subsequently, the effect of the embodiment will be described with reference to FIGS. 9 to 11. FIG. 9 shows three detection modules 130, 132, 134. The detection module 130 does not include a vibration damping member. The detection module 132 includes a vibration damping member 136 at its tip. The detection module 132 is provided with a vibration damping member 136 at the tip end portion and vibration damping plates 138 and 140 at the base end portion.

FIG. 10 shows the experimental results. The horizontal axis shows the elapsed time immediately after transmission, which is the observation time of the artifact signal. The vertical axis shows the amplitude of the artifact signal. The artifact signal is a signal corresponding to acoustic ringing. The characteristic 142 corresponds to the detection module 130, the characteristic 144 corresponds to the detection module 132, and the characteristic 146 corresponds to the detection module 134. Experimental results show that acoustic ringing can be suppressed earlier by providing more damping members on the block body. Although not shown in FIG. 10, according to the configuration in which the split type block main body is provided with two damping plates (the configuration shown in FIG. 5), better characteristics can be obtained than the characteristics 146. Has been confirmed.

In the upper part of FIG. 11, the acoustic ringing 150 generated in the configuration according to the comparative example in which the vibration damping member is not used is schematically shown. Reference numeral 148 indicates a transmission pulse. In the comparative example, it is necessary to set a relatively long dead time 152, followed by a reception period 154.

The lower part of FIG. 11 shows the acoustic ringing 156 that occurs in the configuration according to the embodiment. By adopting the damping member, the period during which the acoustic ringing 156 occurs can be shortened, and the amplitude thereof can also be suppressed. As a result, the dead time 158 can be made considerably shorter than that of the comparative example. That is, it is possible to set the start time of the reception period 160 earlier. This makes it possible to observe the phenomenon immediately after the transmission pulse and improve the reception sensitivity.

10 NMR measurement system, 12 static magnetic field generator, 14 NMR measurement probe, 16 cooling device, 18 circulation device, 24 detection module, 28 sample tube, 46 block body, 54 coil, 56 clamp, 58 support member, 86 vibration damping plate , 88 Anti-vibration plate.

Claims (9)

With the block body
A coil for NMR detection provided on the block body and cooled via the block body,
A vibration damping member made of a material that adheres to the surface of the block body and suppresses acoustic ringing transmitted through the block body after the transmission operation of the coil.
An NMR measurement probe comprising. In the NMR measurement probe according to claim 1,
The block body extends in the vertical direction and
The block body has a tip portion existing on one side in the vertical direction and a base end portion existing on the other side in the vertical direction.
The coil is provided at the tip portion and is provided.
A support member for supporting the base end portion is provided.
An NMR measurement probe characterized by this. In the NMR measurement probe according to claim 2,
The vibration damping member is provided on the surface of the base end portion while being separated from the tip end portion.
An NMR measurement probe characterized by this. In the NMR measurement probe according to claim 2,
The base end portion
A first surface and a second surface having a first width in the horizontal direction orthogonal to the vertical direction,
A third surface and a fourth surface having a second width smaller than the first width in the thickness direction orthogonal to the vertical direction and the horizontal direction.
Have,
The vibration damping member is
The first vibration damping plate in close contact with the first surface and
With the second vibration damping plate in close contact with the second surface,
An NMR measurement probe comprising. In the NMR measurement probe according to claim 4,
A plurality of screws penetrating the laminate including the first damping plate, the base end portion, and the second damping plate are included.
The laminate is fixed to the support member by the plurality of screws.
An NMR measurement probe characterized by this. In the NMR measurement probe according to claim 5,
Each of the plurality of screws is composed of a material that suppresses the acoustic ringing.
An NMR measurement probe characterized by this. In the NMR measurement probe according to claim 2,
The support member is made of a material that suppresses the acoustic ringing.
An NMR measurement probe characterized by this. In the NMR measurement probe according to claim 1,
The material that suppresses acoustic ringing exhibits antiferromagnetism or diamagnetism and has a logarithmic decrement of 0.01 or more at the cooling temperature of the vibration damping member.
An NMR measurement probe characterized by this. In the NMR measurement probe according to claim 1,
The material that suppresses acoustic ringing is a twin crystal type damping material containing manganese as a main component.
An NMR measurement probe characterized by this.

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