JP2009175117A - X-ray analyzer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray analyzer capable of considerably suppressing an influence of an external magnetic field on a TES (transition edge sensor). <P>SOLUTION: The X-ray analyzer comprises the TES 7 receiving an X-ray, detecting its energy as a temperature change and outputting it as a current signal; a superconductive magnetic shield 8 arranging the TES 7 inside and placed in a superconductive state; and a room temperature magnetic shield 9 covering the superconductive magnetic shield 8 and shielding the external magnetic field until the superconductive magnetic shield 8 is placed in the superconductive state. The superconductive magnetic shield 8 and the room temperature magnetic shield 9 are formed in cylindrical shape arranged in mutually concentric circle shape. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is an X-ray analyzer used for an electron microscope, a fluorescent X-ray analyzer, etc., for identifying the element type of a generation source by discriminating the energy of generated X-rays, and particularly for X-ray analysis. The present invention relates to an X-ray analyzer using a superconducting transition edge sensor that converts energy into thermal energy as an X-ray detector.

As an X-ray analysis apparatus capable of discriminating X-ray energy, there are an energy dispersive X-ray detector (Energy Dispersive Spectroscopy, hereinafter referred to as EDS) and WDS (Wavelength Dispersive Spectroscopy, hereinafter referred to as WDS).
The EDS is a type of X-ray detector that converts X-ray energy taken into the detector into an electric signal in the detector and calculates the energy based on the magnitude of the electric signal. The WDS is a type of X-ray detector that monochromatizes X-rays with a spectrometer (energy discrimination) and detects the monochromated X-rays with a proportional counter.

  As EDS, a semiconductor detector such as a SiLi (silicon lithium) type detector is known. By using this semiconductor detector, a wide range of energy of about 0 to 20 keV can be detected, but the energy resolution is as narrow as about 130 eV, which is inferior to 10 times or more as compared with WDS.

  In recent years, superconducting X-ray detectors that are energy dispersive and have an energy resolution equivalent to that of WDS have attracted attention. Among these superconducting X-ray detectors, a detector called a superconducting transition sensor (hereinafter referred to as TES) is a rapid resistance change (ΔT to several It is a highly sensitive thermometer using ΔR to 0.1Ω at mK. This TES is also called a microcalorimeter.

  In this TES, radiation such as primary X-rays or primary electron beams from a radiation source is irradiated onto a sample, and fluorescent X-rays or characteristic X-rays generated from the sample are incident to change the temperature in the TES. The sample is analyzed by controlling. At present, the energy resolution of TES can obtain an energy resolution of 10 eV or less in, for example, 5.9 keV characteristic X-rays (see Non-Patent Document 1).

  When TES is attached to a thermal scanning electron microscope (such as a tungsten filament type) using an electron generation source, characteristic X-rays generated from a sample irradiated with an electron beam are acquired. TES can easily separate characteristic X-rays (Si-Ka, W-Ma, b) that cannot be separated (see Non-Patent Document 2).

  The TES is provided at the tip of a rod-like member called a cold finger that is attached to a cooling device and is close to a sample, like a conventional semiconductor EDS. In addition, since TES using a superconducting material is affected by a magnetic field equivalent to geomagnetism applied to the sensor as an external magnetic field, the sensitivity deteriorates. Therefore, the snout that houses the cold finger has conventionally had a magnetic field for shielding geomagnetism. A shield is provided.

K.D.Irwin, “An application of electrothermal feedback for high resolution cryogenic particle detection”, Applied Physics Letters 66, 1995, 1998. K. Tanaka et al., “A microcalorimeter EDS system suitable for low acceleration voltage analysis”, Surface and Interface Analysis 38, 2006, page 1646.

The following problems remain in the conventional technology.
For example, in the TES described in Non-Patent Document 2, the position of the thermal (tungsten filament type) electron microscope and the TES is several centimeters apart, and the magnetic field is not easily leaked from the electron microscope barrel. Therefore, the influence of the external magnetic field on the sensitivity of the TES was not observed, but in a high-resolution electron microscope (for example, a field emission (field emission) electron microscope), there is a concern about the influence of the leakage magnetic field on the sensitivity of the TES. Is done. That is, in such an electron microscope, an in-lens type or semi-in-lens type objective lens that leaks a magnetic field outside the lens barrel is the mainstream, and a strong magnetic field is used to converge the primary electrons emitted from the field emission cathode. Therefore, the leakage magnetic field may affect the TES characteristics. In addition to electron microscopes and fluorescent X-ray analyzers, it is highly conceivable to use TES while a magnetic field exceeding geomagnetism is generated, and it is desirable that TES operate stably under a strong magnetic field exceeding geomagnetism. ing.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an X-ray analyzer that can significantly suppress the influence of an external magnetic field on a TES.

  The present invention employs the following configuration in order to solve the above problems. That is, the X-ray analyzer of the present invention has a superconducting transition edge sensor that receives X-rays, detects the energy as a temperature change, and outputs it as a current signal; A superconducting magnetic shield formed of a material; a room temperature magnetic shield encapsulating the superconducting magnetic shield and shielding an external magnetic field until the superconducting magnetic shield is in a superconducting state; the superconducting transition edge sensor; A cooling mechanism for cooling the superconducting magnetic shield, wherein the superconducting magnetic shield and the room temperature magnetic shield are cylindrically arranged concentrically with each other.

  In this X-ray analyzer, since the superconducting magnetic shield and the room temperature magnetic shield are cylindrically arranged concentrically with each other, the superconducting magnetic shield and the room temperature magnetic shield have an outer periphery with a constant curvature with respect to the external magnetic field. Since it has a surface, corners or the like that increase the magnetic flux density do not exist on the outer peripheral surface, and the external magnetic field can be prevented from reaching the critical magnetic field due to the concentration of the magnetic flux. Therefore, a good magnetic shielding effect can be maintained, and the sensitivity of TES can be obtained stably and with high accuracy.

  In the X-ray analysis apparatus of the present invention, the critical magnetic field of the superconducting magnetic shield is set to be twice or more the strength of the maximum external magnetic field. As will be described later, when a magnetic field is applied perpendicularly from the side surface in a cylindrical superconducting magnetic shield, the magnetic flux density at the outer peripheral surface of the superconducting magnetic shield becomes twice the strength of the external magnetic field at the maximum. Therefore, in the X-ray analyzer of the present invention, the critical magnetic field of the superconducting magnetic shield is set to be twice or more the strength of the maximum external magnetic field, so that the maximum magnetic flux density generated on the outer peripheral surface of the superconducting magnetic shield is reduced. The necessary magnetic field resistance can be obtained.

  In the X-ray analyzer of the present invention, the superconducting magnetic shield is formed by concentrically laminating a plurality of superconductor layers. That is, in this X-ray analyzer, since the superconducting magnetic shield is formed by concentrically laminating a plurality of superconductor layers, an increase in the number of superconductor surfaces increases the flow of magnetic shield current. Compared with the case of being composed of a single layer, a significantly higher magnetic field shielding effect can be obtained.

  The X-ray analyzer of the present invention is characterized by comprising a copper layer portion laminated on the superconducting magnetic shield. That is, in this X-ray analyzer, since the copper layer portion laminated on the superconducting magnetic shield is provided, the copper layer portion having high thermal conductivity absorbs the heat of the superconducting magnetic shield and transmits it to the outside. A good cooling state can be maintained.

  The X-ray analyzer of the present invention further includes a heat conducting member having a distal end connected to a proximal end of the superconducting magnetic shield and a proximal end connected to the cooling mechanism, The base end portion of the shield and the front end portion of the heat conducting member are formed in a stepped shape that can be fitted to each other. That is, in this X-ray analyzer, the base end portion of the superconducting magnetic shield and the tip end portion of the heat conducting member are formed in a stepped shape that can be fitted to each other. Increases and enables good heat conduction.

  Furthermore, the X-ray analyzer of the present invention includes a high heat conduction auxiliary member formed of aluminum or copper covering the outer peripheral surface of the superconducting magnetic shield across the proximal end portion and the distal end portion of the heat conduction member. It is characterized by having. That is, in this X-ray analyzer, the outer peripheral surfaces of the base end portion of the superconducting magnetic shield and the tip end portion of the heat conducting member are covered with the high heat conduction auxiliary member made of aluminum or copper. High thermal conductivity can be obtained by performing high thermal conduction not only through direct thermal conduction by the connecting portion with the conductive member but also through the high thermal conduction auxiliary member.

The present invention has the following effects.
That is, according to the X-ray analysis apparatus according to the present invention, since the superconducting magnetic shield and the room temperature magnetic shield are in a cylindrical shape arranged concentrically with each other, the external magnetic field is prevented from reaching the critical magnetic field, By maintaining a good magnetic shielding effect, the sensitivity of TES can be obtained stably and with high accuracy. Furthermore, by setting the critical magnetic field of the superconducting magnetic shield to at least twice the strength of the maximum external magnetic field, a superconducting magnetic shield having a magnetic shielding effect corresponding to the strength of the maximum external magnetic field applied to the device is obtained. The TES which is a superconducting X-ray detector can be reliably operated with high accuracy. As a result, an X-ray analyzer that always maintains high energy resolution can be provided.

  Hereinafter, an embodiment of an X-ray analyzer according to the present invention will be described with reference to FIGS. 1 to 6. In each drawing used for the following description, the scale is appropriately changed in order to make each member recognizable or easily recognizable.

  The X-ray analyzer of the present embodiment is an apparatus that can be used as a composition analyzer such as an electron microscope, an ion microscope, an X-ray microscope, and a fluorescent X-ray analyzer, for example, as shown in FIG. The TES (Transition Edge Sensor) 7 is an X-ray detector that receives and detects the energy as a temperature change and outputs it as a current signal. The TES 7 is disposed inside and formed of a superconducting material. And a room temperature magnetic shield 9 that encapsulates the superconducting magnetic shield 8 and shields an external magnetic field until the superconducting magnetic shield 8 is in a superconducting state.

  That is, the X-ray analyzer includes a vacuum vessel 1 that surrounds the entire device, a vacuum tube 2 that is attached to the vacuum vessel 1 so as to protrude in the horizontal direction, and a preliminary cooling mechanism 3 that cools the inside of the vacuum vessel 1. A heat shield plate (heat conduction member) 4 that is connected to the preliminary cooling mechanism 3 and is cooled by the distal end portion being connected to the proximal end portion of the superconducting magnetic shield 8, and the heat shield plate 4 Surrounding cooling device 5 capable of cooling to 300 mK or less, cold finger 6 attached horizontally from cooling device 5, TES 7 attached to the tip of cold finger 6, and heat shield covering TES 7 A superconducting magnetic shield 8 attached to a part of the plate 4, a room temperature magnetic shield 9 covering the superconducting magnetic shield 8 and provided on the exterior of the vacuum tube 2, and a superconducting magnetic shield It includes a copper layer 10 which are laminated to the.

The room temperature magnetic shield 9 is disposed so as to surround the superconducting magnetic shield 8 in contact or non-contact. In addition, the room temperature magnetic shield 9 of this embodiment is arranged surrounding the superconducting magnetic shield 8 in a non-contact state. Further, the superconducting magnetic shield 8 and the room temperature magnetic shield 9 have a cylindrical shape arranged concentrically with the cold finger 6 as the central axis.
The critical magnetic field of the superconducting magnetic shield 8 is set to be at least twice the strength of the maximum external magnetic field.

The superconducting magnetic shield 8 is formed by concentrically laminating a plurality of superconductor layers (not shown). In the superconducting magnetic shield 8 having this laminated structure, when the number of superconductor layers is N and the maximum external magnetic field is B, the critical magnetic field of one superconductor layer is set to 2 B / N or more.
2 is a cross-sectional view of the superconducting magnetic shield 8 shown in FIG. 1 and shows a state in which the copper layer portion 10 having high thermal conductivity is provided on the superconducting magnetic shield 8. FIG.

The vacuum vessel 1 and the vacuum tube 2 form one vacuum chamber. The preliminary cooling mechanism 3, the cooling device 5, and the cold finger 6 provided in the vacuum chamber are insulated by using a vacuum necessary for eliminating heat conduction from the heat shield plate 4.
The preliminary cooling mechanism 3 is used for cooling the heat shield plate 4 and for cooling from room temperature to a temperature at which the cooling device 5 can be operated.

  The cold finger 6 is a cylindrical bar member used to bring the TES 7 as close as possible to the X-ray generation source. The cold finger 6 is made of copper having a high thermal conductivity because it is necessary to cool the TES 7 to near the temperature of the cooling device 5. Further, the superconducting magnetic shield 8 mounted on the heat shield plate 4 is desired to have a temperature equivalent to that of the heat shield plate 4. Although this mounting method is not limited to this, it is preferable to use a copper paste between the heat shield plate 4 and the superconducting magnetic shield 8 and connect them both metallically. In addition, it is preferable to provide several layers of PET films such as Mylar (registered trademark) on the outside of the superconducting magnetic shield 8 in order to cut off heat radiation from the high temperature part.

  Moreover, the said cooling device 5 consists of a refrigerator which can be cooled to 100 mK vicinity, For example, a dilution refrigerator and an adiabatic demagnetization refrigerator can be used. The dilution refrigerator is a refrigerator in which 3He and 4He are separated into two layers in the mixing chamber and cooled by utilizing the enthalpy difference when 3He is dissolved in 4He. The adiabatic demagnetization refrigerator is a refrigerator that absorbs the heat of the object to be cooled by lowering the magnetic field applied to the magnetic salt and increasing the entropy of the magnetic salt.

Both the dilution refrigerator and the adiabatic demagnetization refrigerator can obtain a temperature of 100 mK or less. The temperature at the tip of the cold finger 6 is determined by the amount of heat generated by the TES 7, the thermal conductivity of the cold finger 6, and the heat radiation from the heat shield plate 4. If the material of the cold finger 6 is oxygen-free copper, the material of the heat shield plate 4 is also oxygen-free copper, and if the temperature reached by the preliminary cooling mechanism 3 is 5K or less, the tip temperature and cooling of the cold finger 6 are reduced. The difference from the temperature of the device 5 is about several tens of millikelvins when the temperature of the cooling device 5 is around 100 mK.
Thus, the preliminary cooling mechanism 3, the cooling device 5, and the cold finger 6 function as a cooling mechanism that cools the TES 7 and the superconducting magnetic shield 8.

Next, the cooling process of this apparatus will be described.
After evacuating the vacuum chamber composed of the vacuum vessel 1 and the vacuum tube 2, the pre-cooling mechanism 3 cools the heat shield plate 4, the cooling device 5, and the cold finger 6. Note that the temperature reached by the preliminary cooling mechanism 3 varies depending on the cooling medium used. For example, when the heat shield plate 4, the cooling device 5, and the cold finger 6 are cooled to 5K or less, the precooling mechanism 3 is liquid helium or a mechanical refrigerator.

  In the case of liquid helium, the helium tank corresponds to the preliminary cooling mechanism 3. As the mechanical refrigerator, a Gifford-McMaphon type refrigerator (GM refrigerator) or a pulse tube refrigerator is used. Note that the preliminary cooling mechanism 3 and the cooling device 5 are thermally loosely connected. For example, a thin-walled (<0.5 mm) stainless steel pipe having poor thermal conductivity can be used between the preliminary cooling mechanism 3 and the cooling device 5.

  When the preliminary cooling mechanism 3 and the cooling device 5 are connected with a material having poor thermal conductivity as described above, the time for the temperature of the cooling device 5 to drop to 5K or less is slower than that of a material with good thermal conductivity. Problem occurs. As a means for solving this problem, for example, a rod made of a material having a good thermal conductivity may be inserted between the preliminary cooling mechanism 3 and the cooling device 5 so that the rod can move several millimeters.

  The pre-cooling mechanism 3 cools the cooling device 5 to 5K or less via a rod made of a material having a good thermal conductivity, and then separates the rod from the cooling device 5 by several millimeters, whereby the pre-cooling mechanism 3 and the cooling device 5 Can be separated thermally. Moreover, when liquid helium decompressed is used for the preliminary cooling mechanism 3, the heat shield plate 4, the cooling device 5, and the cold finger 6 can be cooled to 3K or less.

  The room temperature magnetic shield 9 provided on the exterior of the vacuum tube 2 is used to prevent the external magnetic field from leaking into the vacuum tube 2 when the heat shield plate 4, the cooling device 5 and the cold finger 6 are cooled by the preliminary cooling mechanism 3. used. As a material for the room temperature magnetic shield 9, for example, an iron nickel alloy called permalloy can be used. The graph of FIG. 3 is a result of measuring the leakage magnetic field strength in the room temperature magnetic shield 9 when a Hall element is provided in the cylindrical room temperature magnetic shield 9 and the external magnetic field strength is changed.

  The room temperature magnetic shield 9 is provided at a position where one side is completely open and the other side is closed, but a hole of φ6 is opposed to the TES 7. Similarly, holes are provided in the vacuum vessel 1, the copper layer portion 10, and the superconducting magnetic shield 8 at positions facing the TES 7. These holes are used for introducing X-rays from the outside, and a laminated body of aluminum and an organic film or a window member W formed of beryllium is attached in a closed state.

  In the graph of FIG. 3, the horizontal axis represents the external magnetic field (external magnetic field), and the vertical axis represents the leakage magnetic field strength in the room temperature magnetic shield 9. From this graph, it can be seen that the magnetic field leaks when the external magnetic field is 100 to 200 gauss (10 to 20 millitesla). It can also be seen that permalloy cannot shield the magnetic field in a magnetic field environment of 10 to 20 millitesla or more. There are other electromagnetic steel plate materials as the room temperature magnetic shield material, but a leakage magnetic field is generated in the room temperature magnetic shield 9 when the external magnetic field is 100 millitesla or more.

  Further, in order to operate the TES 7 in an environment of 100 millitesla or more, the superconducting magnetic shield 8 is used instead of the room temperature magnetic shield 9. As described above, the room temperature magnetic shield 9 is used to shield the external magnetic field until the superconducting magnetic shield 8 is in a superconducting state. Further, since the magnetic field resistance of the room temperature magnetic shield 9 is about 10 millitesla, when cooling the superconducting magnetic shield 8, it is desirable that the external magnetic field be 1 millitesla or less.

  It is known that the cold finger 6 moves due to thermal contraction when it is cooled from room temperature to 70K. For this reason, it is preferable that the shape of the heat shield plate 4 is a cylinder so that the cold finger 6 does not contact the heat shield plate 4 in any direction. That is, since the shape of the heat shield plate 4 is cylindrical, the shape of the superconducting magnetic shield 8 is also cylindrical.

As the superconducting material constituting the superconducting magnetic shield 8, niobium, niobium titanium and magnesium diboride having a superconducting transition temperature higher than 5K can be used.
In this superconducting magnetic shield 8, FIG. 4 shows a state when a magnetic field is applied vertically from the cylindrical side surface. At this time, in the superconducting magnetic shield 8, the internal magnetic field in the θ direction of the cylinder (cylindrical coordinate system) is given by the following equation.

  In the above formula, a is the radius of the cylinder, and λL is the magnetic field penetration length. However, it is assumed that the thickness of the cylinder in the superconducting magnetic shield 8 is sufficiently thicker than the magnetic field penetration length. However, if the operating temperature of the superconducting magnetic shield 8 is sufficiently lower than the transition temperature of the superconductor to be used, the magnetic field penetration will occur. The length is on the order of nanometers, which is sufficiently thicker than the thickness of the cylinder (on the order of several hundred micrometers).

In the above equation, when θ = 90 degrees, B _max = −2H, and it can be seen that the magnetic field strength twice as much as the applied magnetic field is applied to the end of the cylinder. Therefore, the magnetic field resistance cannot be obtained unless the critical magnetic field of the superconducting magnetic shield 8 has a value more than twice the external magnetic field.

  In order to secure the magnetic field resistance of the superconducting magnetic shield 8, it is effective to use a multilayer of a plurality of superconductor layers instead of a single superconductor layer. Permalloy used for the room temperature magnetic shield 9 loses its magnetic field resistance beyond the saturation magnetic field, so it is effective to increase the cross-sectional area for sucking magnetism, but the superconductor has a surface (depth of magnetic field penetration length). It is important to increase the number of surfaces in order to eliminate the magnetic field by the magnetic shield current flowing in That is, increasing the number of surfaces is nothing but increasing the total number of magnetic shields. Further, when the superconducting magnetic shield 8 is composed of a laminate of a plurality of superconductor layers, as described above, the copper layer portion 10 having a high thermal conductivity may be laminated in the laminate to cool the inside of the shield. It is valid.

  FIG. 5 is a diagram showing the relationship between the critical current of the TES 7 that is a superconductor and the external magnetic field when the superconducting magnetic shield 8 in which 30 layers of niobium titanium and copper are laminated is attached to the heat shield plate 4.

  The TES 7 includes a thermometer composed of an absorber such as a metal band, a semimetal, a superconductor, etc. for absorbing X-rays, a superconductor that detects heat generated in the absorber as a temperature change, and a thermometer. And a membrane for controlling a heat flow rate to escape to the heat tank. For example, it is possible to employ aluminum as the absorber, a material composed of two layers of titanium and gold as the thermometer, and silicon as the membrane and the heat bath.

The TES 7 is connected in parallel with a shunt resistor (not shown) smaller than the resistance value during normal conduction of the TES 7 in parallel, and a superconducting quantum interference device amplifier (SQUID amplifier) for reading out a current change generated in the TES 7 (illustrated) Abbreviation) is provided in series with the TES 7.
When a bias current of 100 mA is applied to the TES 7, when the TES 7 is in a superconducting state, the bias current does not flow through the shunt resistor but the entire current flows through the TES 7.

  In the present embodiment, it is defined that the magnetic field effect on the TES 7 is generated when the current flowing through the TES 7 becomes 100 mA or less. As a result, when NbTi was 30 layers, the maximum value of the external magnetic field resistance was 130 mT. This result is a numerical value that cannot be obtained with Permalloy alone. From this result, it can be seen that, in order to give a magnetic field resistance of, for example, about 500 mT, about 120 layers of NbTi may be stacked instead of 30 layers.

  As described above, in this embodiment, the room temperature magnetic shield 9 provided on the exterior of the vacuum tube 2 and the superconducting magnetic shield 8 provided inside the room temperature magnetic shield 9 have a cylindrical shape arranged concentrically with each other. Therefore, since the superconducting magnetic shield 8 and the room temperature magnetic shield 9 have the outer peripheral surface having a constant curvature with respect to the external magnetic field, there are no corners or the like that increase the magnetic flux density on the outer peripheral surface, and the external magnetic field due to the concentration of the magnetic flux. It can suppress that a magnetic field reaches a critical magnetic field. Therefore, a good magnetic shielding effect can be maintained, and the sensitivity of TES 7 can be obtained stably and with high accuracy.

In addition, since the critical magnetic field of the superconducting magnetic shield 8 is set to be twice or more the strength of the maximum external magnetic field, the magnetic field resistance necessary for the maximum magnetic flux density generated on the outer peripheral surface of the superconducting magnetic shield 8 is obtained. Obtainable.
As described above, according to the present invention, the room temperature magnetic shield 9 and the superconducting magnetic shield 8 are disposed concentrically, and the critical magnetic field of the superconducting magnetic shield 8 is more than twice the maximum external magnetic field. Thus, the X-ray analysis system can be reliably operated in a magnetic field environment of 100 mT or more.

Further, since the superconducting magnetic shield 8 is formed by concentrically laminating a plurality of superconductor layers, the superconductor magnetic shield 8 is formed of a single layer by increasing the number of superconductor surfaces and increasing the flowing magnetic shield current. As compared with the case, the magnetic field shielding effect can be obtained significantly higher.
Further, since the copper layer portion 10 laminated on the superconducting magnetic shield 8 is provided, the copper layer portion 10 having a high thermal conductivity absorbs the heat of the superconducting magnetic shield 8 and transmits it to the outside so that the cooling is good. The state can be maintained.

  Next, another example of an embodiment of the X-ray analyzer according to the present invention will be described with reference to FIG.

In the X-ray analyzer which is another example of the present embodiment, the base end portion of the superconducting magnetic shield 8 and the tip end portion of the heat shield plate 4 are formed in a stepped cross-section that can be fitted to each other.
In another example of this embodiment, the base end portion of the superconducting magnetic shield 8 and the tip end portion of the heat shield plate 4 are formed in a cross-sectional step shape that can be fitted to each other. The contact area increases and good heat conduction is possible.

In this X-ray analyzer, a cylindrical high heat conduction auxiliary member formed of aluminum or copper covering the outer peripheral surface of the superconducting magnetic shield 8 and the distal end portion of the heat shield plate 4 is covered. 20 is provided.
In this case, since the outer peripheral surfaces of the base end portion of the superconducting magnetic shield 8 and the front end portion of the heat shield plate 4 are covered with the high heat conduction auxiliary member 20 made of aluminum or copper, the superconducting magnetic shield 8 and the heat shield plate are covered. High thermal conductivity can be obtained by performing high thermal conduction not only through direct thermal conduction by the connecting portion with 4 but also through the high thermal conduction auxiliary member 20.

  When the high heat conduction auxiliary member 20 is not provided, the heat shield plate 4 and the superconducting magnetic shield 8 are fitted, and the surfaces of the heat shield plate 4 and the superconducting magnetic shield 8 are the same and are flush with each other. As a result, there is no step between the two. In particular, when the diameter of the vacuum tube 2 is small, it is better to make the thickness of the heat shield plate 4 as thin as possible in order to prevent contact with the heat shield plate 4 at different temperatures. Under such a requirement, the above-mentioned fitting type is effective.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, by providing a mechanism to monitor the superconducting magnetic shield so that it does not enter a magnetic field higher than the critical magnetic field before the superconducting transition, it is possible to reliably eliminate the magnetic flux traps in the superconducting magnetic shield. it can.

It is a schematic longitudinal cross-sectional view which shows one Embodiment of the X-ray analyzer by this invention. It is the sectional view on the AA line of FIG. It is a graph which shows the residual magnetic field characteristic in a magnetic shield when a magnetic field is applied to one room temperature magnetic shield layer. It is explanatory drawing which shows an internal magnetic field when a magnetic field is applied perpendicularly from the side surface of a cylindrical superconducting magnetic shield. It is a graph which shows the critical current characteristic with respect to a magnetic field when the room temperature magnetic shield 1 layer and a superconductive magnetic shield are used together, and the X-ray detector (TES) which consists of a superconductor is arrange | positioned in a superconductive magnetic shield. In one Embodiment of the X-ray analyzer by this invention, it is an expanded sectional view of the insertion part of the heat shield board and superconducting magnetic shield which show another example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Vacuum container, 2 ... Vacuum tube, 3 ... Pre-cooling mechanism, 4 ... Heat shield plate (heat conduction member), 5 ... Cooling device, 6 ... Cold finger, 7 ... TES (superconducting transition edge sensor), 8 ... Super Conductive magnetic shield, 9 ... room temperature magnetic shield, 10 ... copper layer, 20 ... high heat conduction auxiliary member

Claims (6)

A superconducting transition edge sensor that receives X-rays, detects its energy as a temperature change, and outputs it as a current signal;
A superconducting magnetic shield disposed within the superconducting transition edge sensor and formed of a superconducting material;
A room temperature magnetic shield that encapsulates the superconducting magnetic shield and shields an external magnetic field until the superconducting magnetic shield becomes superconductive;
A cooling mechanism for cooling the superconducting transition edge sensor and the superconducting magnetic shield,
The X-ray analysis apparatus characterized in that the superconducting magnetic shield and the room temperature magnetic shield are cylindrically arranged concentrically with each other. The X-ray analyzer according to claim 1,
An X-ray analyzer characterized in that a critical magnetic field of the superconducting magnetic shield is set to at least twice the strength of a maximum external magnetic field. In the X-ray analyzer according to claim 1 or 2,
An X-ray analyzer characterized in that the superconducting magnetic shield is formed by concentrically laminating a plurality of superconductor layers. In the X-ray analyzer according to any one of claims 1 to 3,
An X-ray analyzer comprising a copper layer portion laminated on the superconducting magnetic shield. In the X-ray analyzer according to any one of claims 1 to 4,
A heat conduction member having a distal end connected to the proximal end of the superconducting magnetic shield and a proximal end connected to the cooling mechanism;
An X-ray analyzer characterized in that a base end portion of the superconducting magnetic shield and a tip end portion of the heat conducting member are formed in a stepped shape that can be fitted to each other. The X-ray analyzer according to claim 5,
An X-ray analysis comprising a high heat conduction auxiliary member formed of aluminum or copper covering the outer peripheral surface of the superconducting magnetic shield across the base end portion and the tip end portion of the heat conducting member apparatus.

Images