JP2012110489A - Magnetism measuring instrument, and method for manufacturing magnetism sensor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetism measuring instrument capable of measuring magnetism of sufficient intensity from a measuring target, and a method for manufacturing a magnetism sensor element.SOLUTION: The magnetism measuring instrument includes a detector 1 for detecting magnetism using electronic spin resonance and a base part 7 loaded with the detector 1. The detector 1 has the magnetism sensor element 1a provided to the leading end part 1b thereof and the magnetism sensor element 1a comprises diamond for outputting an electron spin resonance signal. The diamond of the magnetism sensor element 1a contains aC atom with an atom concentration of 0.01% or below and a nitrogen atom with an atom concentration of 100 ppm or below and the number of nitrogen atoms contained in the diamond of the magnetism sensor element 1a and adjacent to the vacancy in the diamond is 5% or above of the number of the nitrogen atoms contained in the diamond of the magnetism sensor element 1a. A base part 7 has a main surface and also has a position adjusting part for adjusting the position of the leading end part 1b in the direction crossing the main surface.

Description

  The present invention relates to a magnetic measuring device and a method for manufacturing a magnetic sensor element.

  Conventionally, magnetic sensors such as a SQUID (Superconducting Quantum Interference Device) used at a liquid helium temperature and a high-temperature superconducting SQUID operating at a liquid nitrogen temperature are known (Non-Patent Document 1). Any of such magnetic sensors has a magnetic detection sensitivity of fT / √ (Hz).

JP-A-6-263418

Editor: John Clarke and Alex I. Braginski, Title: “The SQUID Handbook”, Volume: Vol. 1, pp. 171-250, Country: Germany, Publisher: WILEY-VCH JRMaze, PL Stanwix, JS Hodges, S. Hong, JM Taylor, P. Cappellaro, L. Jiang, MV Gurudev Dutt, E. Togan, AS Zibrov, A. Yacoby, RL Walsworth & MD Lukin, “Nanoscale magnetic sensing with an individual electronic spin in diamond ”, Nature 455, 644-647 (2 October 2008)

  However, since a conventional magnetic sensor using such a SQUID has a relatively low operating temperature, a heat insulating layer and a refrigerant layer are required between the magnetic sensor and the object. Since the heat insulating layer and the refrigerant layer are provided between the magnetic sensor and the object, the distance between the magnetic sensor and the object is relatively long. For this reason, it is difficult to measure a sufficiently strong magnetism from a measurement object using a conventional magnetic sensor. In view of the above, an object of the present invention is to provide a magnetic measuring device and a method for manufacturing a magnetic sensor element that can measure magnetism with sufficient strength from a measurement target.

A magnetic measurement device according to one aspect of the present invention includes a detector that detects magnetism using electron spin resonance, and a base portion on which the detector is mounted. The detector has a magnetic sensor element provided at the tip of the detector, and the magnetic sensor element is made of diamond that outputs an electron spin resonance signal, and the diamond of the magnetic sensor element is 0.01 % Of atomic concentration of ¹³ C atoms and nitrogen atoms of atomic concentration of 100 ppm or less, contained in diamond of the magnetic sensor element and adjacent to vacancies in the diamond of the magnetic sensor element. The number is 5% or more of the number of nitrogen atoms contained in diamond of the magnetic sensor element, the base portion has a main surface, and the position of the tip portion intersects the main surface. It has the position adjustment part for adjusting with a direction, It is characterized by the above-mentioned.

According to this magnetic measurement apparatus, since the atomic concentration of ¹³ C atoms is 0.01% or less, the electrical and optical heat generation generated in the magnetic sensor element is sufficiently reduced. Thus, since the atomic concentration of ¹³ C atoms is relatively low, the atomic concentration of nitrogen atoms that do not constitute the NV center is also low. Therefore, the spin relaxation time becomes relatively long, and biomagnetic signals (magnetic signals emitted from a living body such as a human) can be measured. That is, since the atomic concentration of ¹³ C having a nuclear spin as a noise source is 0.01% or less, the magnetism of the order of nT (nano Tesla) or less (ie, aT (atto Tesla) or more and nT or less)) It can be measured in the light irradiation ESR measurement (ODMR). This is because the longer the spin relaxation time, the sharper the ESR microstructure. ^{By making} the atomic concentration of ¹³ C concentration 0.01% or less, the spin relaxation time can be increased to about 20 ms. For example, when the atomic concentration of ¹³ C atoms is 1.1%, the spin relaxation time is about several μs to 100 μs. An example of measuring magnetism using light-irradiated ESR measurement (ODMR) of diamond is disclosed in a known document ("Nature" 455 (2008) 644). In this known document, it is possible to measure magnetism of 0.5 μT (micro Tesla) / √Hz or more using natural diamond. In the above-mentioned known literature, the atomic concentration of ¹³ C atoms having a nuclear spin is 1.1%. Therefore, the spin relaxation time is relatively short due to the atomic concentration of ¹³ C atoms. For this reason, the present inventor considers that it is impossible to measure magnetism below 0.5 μT / √Hz by the technique of the above-mentioned known literature, while reducing the atomic concentration of ¹³ C atoms having a nuclear spin and impurities (nitrogen). It was considered that the measurement of magnetism of less than 0.5 μT / √Hz is possible by reducing the atomic concentration. Therefore, a diamond crystal having an atomic concentration of ¹³ C atoms and an atomic concentration of impurities (nitrogen) suitable for a magnetic sensor element was synthesized, and the present invention was achieved.

  According to this magnetic measuring device, since the atomic concentration of nitrogen atoms contained in diamond of the magnetic sensor element is 100 ppm or less, generation of a minute magnetic field that suppresses ESR (Electron Spin Resonance) is reduced.

  Nitrogen atoms that are not adjacent to vacancies suppress the magnetic detection sensitivity. According to this magnetic measurement device, among the nitrogen atoms contained in diamond of the magnetic sensor element, the nitrogen contained in this diamond Since the number of nitrogen atoms of 5% or more of the total number of atoms is adjacent to the vacancies, sufficient magnetic detection sensitivity can be obtained.

  According to this magnetic measurement apparatus, the main surface of the base portion is arranged along the surface of the magnetic measurement target, and the magnetic sensor element at the tip of the detector mounted on the base portion is sufficiently brought close to the surface of the measurement target. Therefore, a relatively strong magnetic field can be measured from the measurement target.

  In this magnetic measurement apparatus, the atomic concentration of boron atoms contained in diamond of the magnetic sensor element is less than 1 ppm. According to this magnetic measuring device, since the atomic concentration of boron atoms is extremely low, the magnetic sensor element has sufficient insulation. Therefore, it is possible to directly form a coil with metal wiring on the magnetic sensor element.

  In this magnetic measurement device, the base portion is provided with a hole penetrating from the main surface to the back surface of the base portion, and the position adjusting portion has one or a plurality of O-rings, A hole portion of the O-ring communicates with a hole portion of the base portion, and the detector is in contact with the one or more O-rings, and each of the hole portions of the one or more O-rings and the holes of the base portion. Inserted into the section.

  According to this magnetic measurement device, the detector is inserted into the hole of the O-ring and the hole of the base portion in contact with the O-ring of the position adjusting unit, and therefore the friction between the detector and the O-ring. With this, the detector is stably held by the base portion, and the magnetic sensor element is disposed in the direction intersecting the main surface of the base portion (the direction in which the hole of the base portion into which the detector is inserted extends). The position of the tip of the detector can be adjusted with sufficient accuracy (for example, with a length of 1 mm as a unit).

  In this magnetic measuring device, the base portion has two groove portions provided at the respective edge portions of the two openings of the hole portion of the base portion, and the position adjusting portion has two O-rings. , One O-ring of the two O-rings is disposed in one groove of the two grooves, and the other O-ring of the two O-rings is out of the two grooves. It is arrange | positioned at the other groove part.

  According to this magnetic measuring device, one of the two O-rings is disposed in a groove provided at the edge of one opening of the hole of the base, and the other of the two O-rings. Since the O-ring is arranged in a groove provided at the edge of the other opening of the base portion, one of the two O-rings is arranged on the main surface side of the base portion, and the other is the base. It is arranged on the back side of the part. And a detector is inserted in the hole of these two O-rings, and the hole of a base part. Therefore, the friction between the outer surface of the detector and the two O-rings keeps the detector sufficiently stable on the base portion, and also in the direction intersecting the main surface of the base portion (the base portion in which the detector is inserted). In the direction in which the hole extends, the position of the tip of the detector on which the magnetic sensor element is arranged can be adjusted with relatively high accuracy.

  In this magnetic measuring device, the position adjusting portion is provided on the main surface and extends above the main surface, a cylindrical protruding portion, a cap portion screwed into the protruding portion, and an end surface of the protruding portion And an O-ring provided between the cap portion and the cap portion, the protruding portion and the cap portion are screwed together with the O-ring sandwiched therebetween, and the base portion is A hole penetrating the back surface of the base portion is provided, the protruding portion has a side wall extending on the main surface, a screw groove is formed on an outer surface of the side wall of the protruding portion, and the cap portion is A side wall and a bottom wall extending in a direction crossing the side wall, and an inner surface of the side wall of the cap part is formed with a thread groove that can be screwed with the protruding part, and the bottom of the cap part The wall is provided with a hole penetrating the bottom wall, the hole of the bottom wall of the cap part, The hole portion of the O-ring, the cylindrical hole of the protruding portion, and the hole portion of the base portion communicate with each other, and the detector is in contact with the O-ring, and the hole portion of the bottom wall of the cap portion, Inserted into the hole of the ring, the cylindrical hole of the protrusion, and the hole of the base, and the O-ring is sandwiched between the end surface of the protrusion and the bottom wall of the cap. It is characterized by.

  According to this magnetic measuring device, the detector is inserted into the hole of the base part, the cylindrical hole of the projecting part, the hole of the O-ring, and the hole of the bottom wall of the cap part. It is held stably in the part. Further, since the cap part is screwed into the projecting part in a state where the O-ring is sandwiched between the bottom wall of the cap part and the end surface of the projecting part, the O-ring is provided with the end wall of the cap part and the end surface of the projecting part And are crushed and deformed, and the diameter of the hole of the O-ring becomes relatively small. For this reason, the friction between the detector inserted into the hole of the deformed O-ring and the O-ring becomes relatively large, and thus the detector is held on the base portion in a more stable state.

A method of manufacturing a magnetic sensor element according to one aspect of the present invention is a method of manufacturing a magnetic sensor element included in any one of the above-described magnetic measurement apparatuses, and includes ¹³ C atoms having an atomic concentration of 0.01% or less, 0 A step of preparing a single crystal diamond containing a nitrogen atom having an atomic concentration of 1 ppm or less and a boron atom having an atomic concentration of less than 1 ppm, an energy of 10 keV or more and 3 MeV or less, and 1 × 10 ¹³ / cm ⁻² or more Injecting nitrogen atoms into the single crystal diamond at an atomic concentration of 1 × 10 ²⁰ / cm ⁻² or less, and within a range of 1 hour to 3 hours, a range of 600 ° C. to 1400 ° C. Heating the single crystal diamond after the ion implantation at a temperature.

According to this method of manufacturing a magnetic sensor element, if the atomic concentration of ¹³ C atoms is 0.01% or less, the thermal conductivity increases up to 1.5 times that when carbon having a natural abundance is used. Electrical and optical heat generation occurring in the sensor element is sufficiently reduced.

According to this method for manufacturing a magnetic sensor element, since the atomic concentration of boron atoms is extremely low, the magnetic sensor element has sufficient insulation.
Therefore, it is possible to directly form a coil with metal wiring on the magnetic sensor element.

According to this method of manufacturing a magnetic sensor element, nitrogen atoms are added to single crystal diamond at an energy of 10 keV to 3 MeV and an atomic concentration of 1 × 10 ¹³ / cm ^{−2 to} 1 × 10 ²⁰ / cm ⁻² . After the ion implantation, the single crystal diamond after the ion implantation is heated at a temperature in the range of 600 degrees Celsius or more and 1400 degrees Celsius or less within a period of 1 hour or more and 3 hours or less. By performing such ion implantation and heating, the atomic concentration of nitrogen atoms in the single crystal diamond is 100 ppm or less, and the nitrogen atoms adjacent to the vacancies are 5% or more of the nitrogen atoms contained in the single crystal diamond. It becomes. Therefore, since generation of a minute magnetic field that suppresses ESR is reduced, sufficient magnetic detection sensitivity can be obtained.

A method of manufacturing a magnetic sensor element according to one aspect of the present invention is a method of manufacturing a magnetic sensor element included in any one of the above-described magnetic measurement apparatuses, and includes ¹³ C atoms having an atomic concentration of 0.01% or less, 0 A step of preparing a single crystal diamond containing a nitrogen atom having an atomic concentration of more than 1 ppm and a boron atom having an atomic concentration of less than 1 ppm, an energy of 0.7 MeV to 10 MeV, and an irradiation dose of 1 Gy to 1 GGy The step of irradiating the single crystal diamond with an electron beam and the single crystal after the electron beam irradiation at a temperature in the range of 600 degrees Celsius to 1400 degrees Celsius within a period of 3 hours to 4 hours Heating the diamond.

According to this method for manufacturing a magnetic sensor element, since the atomic concentration of ¹³ C atoms is 0.01% or less, the electrical and optical heat generated in the magnetic sensor element is sufficiently reduced.

  According to this method for manufacturing a magnetic sensor element, since the atomic concentration of boron atoms is extremely low, the magnetic sensor element has sufficient insulation. Therefore, it is possible to directly form a coil with metal wiring on the magnetic sensor element.

  According to this method of manufacturing a magnetic sensor element, single crystal diamond is irradiated with an electron beam at an energy of 0.7 MeV to 10 MeV and an irradiation dose of 1 Gy to 1 GGy, and thereafter, 3 hours to 4 hours. The single crystal diamond after the electron beam irradiation is heated at a temperature in the range of 600 degrees Celsius or more and 1400 degrees Celsius or less within the period of time. By performing such electron beam irradiation and heating, the atomic concentration of nitrogen atoms in the single crystal diamond is 100 ppm or less, and the nitrogen atoms adjacent to the vacancy are 5 nitrogen atoms contained in the single crystal diamond. % Or more. Therefore, generation of a minute magnetic field for suppressing ESR is reduced, and sufficient magnetic detection sensitivity can be obtained. In addition, since single crystal diamond containing nitrogen atoms having an atomic concentration of 0.1 ppm or more is used, a magnetic sensor element can be manufactured at a lower cost than when ion implantation is used. That is, in order to uniformly implant ions in the depth direction of the crystal thickness in ion implantation, it is necessary to implant a plurality of times while changing the acceleration voltage. If the electron beam irradiation is performed using single crystal diamond containing nitrogen atoms having an atomic concentration of 1, a magnetic sensor element can be manufactured at a lower cost.

  ADVANTAGE OF THE INVENTION According to this invention, the magnetic measuring device which can measure the magnetism of sufficient intensity | strength from the measurement object of a magnetism, and the manufacturing method of a magnetic sensor element can be provided.

FIG. 1 is a diagram illustrating an example of a configuration of a magnetic measurement device according to the embodiment. FIG. 2 is a diagram illustrating a configuration of an optical transmission / reception unit of the magnetic measurement apparatus according to the embodiment. FIG. 3 is a diagram illustrating a usage example of the magnetic measurement device according to the embodiment. FIG. 4 is a diagram for explaining a configuration in which the base unit of the magnetic measurement device according to the embodiment holds the detector. FIG. 5 is a diagram for explaining another configuration in which the base unit of the magnetic measurement device according to the embodiment holds the detector. 6 is an exploded perspective view of the configuration shown in FIG. FIG. 7 is a diagram for explaining an internal configuration of the detector of the magnetic measurement device according to the embodiment. FIG. 8 is a flowchart for explaining a method of manufacturing a magnetic sensor element of the magnetic measurement device according to the embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the description of the drawings, if possible, the same elements are denoted by the same reference numerals, and redundant description is omitted. As shown in FIG. 1, the magnetic measurement device 100 includes a detector 1, an optical transmission / reception unit 3, a control device 5, and a base unit 7.

  The detector 1 detects magnetism using electron spin resonance (ESR). The detector 1 has a cylindrical outer casing. The end surface of the casing of the detector 1 has a size that can be accommodated in, for example, a square having a side of 5 mm, and the length in the longitudinal direction of the casing of the detector 1 is 2 cm or more and 4 cm or less. The detector 1 has a magnetic sensor element 1a. The magnetic sensor element 1 a is provided at the tip 1 b of the detector 1. The magnetic sensor element 1a is made of diamond that outputs an ESR signal. The electron spin resonance signal is red fluorescence (wavelength 637 nm) emitted by electron spin resonance generated by the magnetic sensor element 1a in response to green light (wavelength 532 nm). The type of diamond crystal of the magnetic sensor element 1a is between the IIa type and the Ib type (the nitrogen concentration is 0.1 ppm or less for the IIa type, 100 ppmn or more and 200 ppmn or less for the Ib type, and the region between the IIa type and the Ib type. Corresponds to a nitrogen concentration of 0.1 ppm to 100 ppm.

  ESR is widely used to measure magnetism from materials. The spin of a defect (referred to as an NV center) in which nitrogen and vacancies in diamond are combined has been proved to be suitable for magnetic measurement because it causes zero-field splitting. In diamond, there are also spins of nitrogen and magnetic ions, but the NV center can emphasize the ESR signal by supplying light, so it is strictly distinguished from the spins of nitrogen and magnetic ions. can do. The NV center absorbs green light and fluoresces red light, but when ESR occurs, the intensity of red light decreases. The magnetic measurement device 100 measures magnetism by measuring a change in intensity of received light (red light) from the detector 1. In the ESR, since the magnetism in the material is also affected by the external magnetic field, it is necessary to sufficiently reduce the external magnetic field in order to measure the magnetism with high accuracy.

The diamond of the magnetic sensor element 1a contains ¹³ C atoms having an atomic concentration of 0.01% or less. ^Since the atomic concentration of ¹³ C atoms is 0.01% or less, the electric and optical heat generated in the magnetic sensor element 1a is sufficiently reduced. Thus, since the atomic concentration of ¹³ C atoms is relatively low, the atomic concentration of nitrogen atoms that do not constitute the NV center is also low. Therefore, the spin relaxation time becomes relatively long, and the biomagnetic signal can be measured. That is, since the atomic concentration of ¹³ C is 0.01% or less, magnetism of the order of nT (nano Tesla) or less (range of aT or more and nT or less) can be measured by light irradiation ESR measurement (ODMR) of diamond. This is because the longer the spin relaxation time, the sharper the ESR microstructure. ^{By making} the atomic concentration of ¹³ C concentration 0.01% or less, the spin relaxation time becomes about 20 ms. For example, the spin relaxation time when the atomic concentration of ¹³ C atoms is 1.1% is about 100 μs. The total amount (number) of nitrogen atoms is measured by ESR and SIMS (Secondary Ion Mass Spectrometry). The amount (number) of nitrogen atoms adjacent to the NV center can be estimated from the measured atomic concentration.

  The diamond of the magnetic sensor element 1a contains nitrogen atoms having an atomic concentration of 100 ppm or less. Since the atomic concentration of nitrogen atoms contained in diamond of the magnetic sensor element 1a is 100 ppm or less, generation of a minute magnetic field that suppresses ESR is reduced.

  The diamond of the magnetic sensor element 1a can contain, for example, nitrogen atoms having an atomic concentration of 1 ppb or more and 100 ppm or less. The number of nitrogen atoms contained in the diamond of the magnetic sensor element 1a and adjacent to the vacancies in the diamond of the magnetic sensor element 1a is 5% or more of the number of nitrogen atoms contained in the diamond of the magnetic sensor element 1a. It is. Nitrogen atoms that are not adjacent to vacancies suppress the magnetic detection sensitivity. In the case of the magnetic sensor element 1a, among the nitrogen atoms contained in the diamond of the magnetic sensor element 1a, the nitrogen contained in the diamond. Since the number of nitrogen atoms of 5% or more of the total number of atoms is adjacent to the vacancies, sufficient magnetic detection sensitivity can be obtained. Magnetic detection sensitivity is represented by the minimum detectable magnetic field. The magnetic detection sensitivity is measured using ODMR. This measurement method using ODMR is a measurement method that utilizes the fact that the NV-center fluorescence intensity changes because the magnetic resonance frequency of the NV-center shifts depending on the strength of the magnetic field.

  The diamond of the magnetic sensor element 1a can contain boron atoms. The atomic concentration of boron atoms contained in the diamond of the magnetic sensor element 1a is less than 1 ppm. Since the atomic concentration of boron atoms is extremely low, the magnetic sensor element 1a has sufficient insulation. Accordingly, it is possible to directly form a coil by metal wiring on the magnetic sensor element 1a.

  The optical transmission / reception unit 3 is connected to the control device 5. As shown in FIG. 2, the optical transmission / reception unit 3 includes an oscillation device 3a, an optical transmission device 3b, and an optical reception device 3c. The plurality of optical transmission / reception units 3 are included in the optical transmission / reception unit group 31 as shown in FIG. All of the plurality of optical transmission / reception units 3 included in the magnetic measurement device 100 are stored in the housing of the optical transmission / reception unit group 31.

  The oscillation device 3a is connected to the detector 1 via an electric cable K1. The oscillation device 3a outputs an electrical signal to the detector 1 via the electrical cable K1. The electrical signal output from the oscillation device 3a to the detector 1 includes a high-frequency signal output to the magnetic sensor element 1a, an electrical signal output to a coil 1d (described later) of the detector 1, and the detector 1 And an electric signal output to a coil 1g (see FIG. 7) described later. The optical transmission device 3b is connected to the detector 1 via an optical fiber K2. The optical transmission device 3b transmits light to the detector 1 via the optical fiber K2. The light transmitted from the optical transmission device 3b to the detector 1 is green light having a wavelength of 532 nm. The optical receiver 3c is connected to the detector 1 via the optical fiber K2. The optical receiver 3c receives light from the detector 1 via the optical fiber K2. The light received by the optical receiver 3c from the detector 1 is red light (electron spin resonance signal) having a wavelength of 637 nm. The electric cable K1 and the optical fiber K2 are collected and constitute one cable K.

  One detector 1 is connected to one optical transmission / reception unit 3. When one detector 1 and one optical transmission / reception unit 3 are set as one set, the magnetic measurement device 100 includes a plurality of sets (for example, 20 sets or more and 100 sets or less). In FIG. 1 and the like, only two sets of the detector 1 and the optical transmission / reception unit 3 are shown for the sake of simplicity.

  The control device 5 is a device that controls the operation of the optical transceiver unit 3. The control device 5 has a CPU and a memory (ROM, RAM, etc.). The control device 5 can further include a display. The CPU of the control device 5 comprehensively controls the operation of the control device 5 by executing a computer program stored in the memory of the control device 5. The control device 5 analyzes the electron spin resonance signal from the detector 1 acquired by the optical transmission / reception unit 3. The control device 5 can display the analysis result of the electron spin resonance signal on the display of the control device 5. The control device 5 can store the analysis result of the electron spin resonance signal in the memory of the control device 5.

  The base unit 7 is equipped with one or a plurality of detectors 1. The base part 7 has the shape of a helmet as an example. As an example, the base part 7 is connected to a backrest of a chair such as the support device 9 via an arm 11. Further, a hole 9 a through which a plurality of cables K are passed is provided on the back of the chair of the support device 9. One end of the cable K is connected to one detector 1 mounted on the base portion 7, and the other end is connected to one optical transmission / reception unit 3 stored in the optical transmission / reception unit group 31.

  The base portion 7 has a main surface F1. The base part 7 has a plurality of position adjusting parts. Each of the position adjustment units of the base unit 7 adjusts the position of the tip 1b of the detector 1 in a direction intersecting the tip 1b (normal direction of the main surface F1). Each of the position adjustment portions of the base portion 7 has one or a plurality of O-rings. The position adjustment unit of the base unit 7 is provided for each detector 1. One position adjustment unit adjusts the position of one detector 1. A magnetic shielding sheet, for example, Permalloy, is provided on the front surface of each of the main surface F1 and the back surface F2 of the base portion 7. The material of the base portion 7 can be, for example, an aluminum alloy. In this case, a permalloy coating can be applied to the surface of the aluminum alloy. The material of the base part 7 can be, for example, plastic. In this case, the surface of plastic or the like can be coated with aluminum and permalloy. The material of the base portion 7 (including the coating material) may be any material having a magnetic shielding effect, such as silver, copper, gold, brass, or nickel.

  As shown in FIG. 1, the magnetic measurement apparatus 100 according to the embodiment has a configuration that measures the magnetism of a human head as an example. The base part 7 has the shape of a helmet that covers the head. In addition, the shape of the base part 7 is not restricted to the shape of a helmet. For example, it may be a sheet-like base portion 7 that can cover the back, chest, waist, or the like. The base portion 7 may be hard and difficult to deform, but may be flexible and relatively easy to deform.

  With reference to FIG. 4, the structure in which the base part 7 hold | maintains the detector 1 is demonstrated concretely. 4A has a pair of O-rings (that is, an O-ring 11a and an O-ring 11b). The base portion 7 is provided with a hole portion 7a penetrating from the main surface F1 to the back surface F2 of the base portion 7. One detector 1 is inserted into one hole 7a. The front end 1 b of the detector 1 is on the back surface F <b> 2 of the base portion 7, and the other end of the detector 1 is on the main surface F <b> 1 of the base portion 7. The hole 11a1 of the O-ring 11a of the position adjusting unit, the hole 11b1 of the O-ring 11b of the position adjusting unit, and the hole 7a of the base unit 7 communicate with each other.

  The base part 7 includes an opening 7a1 of the hole 7a of the base part 7, an edge part 7a2 of the opening 7a3, and a groove part 7b1 and a groove part 7b2 provided in the edge part 7a4. The groove part 7b1 is provided in the edge part 7a2, and the edge part 7a2 is an edge part of the opening 7a1. The groove portion 7b1 is provided on the main surface F1 side of the base portion 7. The groove part 7b2 is provided in the edge part 7a4, and the edge part 7a4 is an edge part of the opening 7a3. The groove portion 7b2 is provided on the back surface F2 side of the base portion 7. The O-ring 11a is disposed in the groove 7b1, and the O-ring 11b is disposed in the groove 7b2. The detector 1 is inserted into the hole 11a1 of the O-ring 11a, the hole 11b1 of the O-ring 11b, and the hole 7a of the base 7 in contact with the O-ring 11a and the O-ring 11b, respectively.

  The main surface F1 and the back surface F2 of the helmet-shaped base portion 7 are arranged along the surface of the magnetic measurement target, and the magnetic sensor element 1a of the tip 1b of the detector 1 mounted on the base portion 7 is the measurement target. Since the surface can be sufficiently close to the surface, a relatively strong magnetic field can be measured from the measurement target.

  The detector 1 is in contact with the O-ring 11a and the O-ring 11b included in the position adjustment unit of the base 7 and is connected to the hole 11a1 of the O-ring 11a, the hole 11b1 of the O-ring 11b, and the hole 7a of the base 7. Since it is inserted, the detector 1 is stably held by the base portion 7 due to friction between the detector 1 and the O-ring 11a and the O-ring 11b, and the direction intersecting the main surface F1 of the base portion 7 (detection) The position of the tip 1b of the detector 1, that is, the magnetic sensor element 1a, in the direction in which the hole 7a of the base 7 into which the device 1 is inserted is sufficiently accurate (for example, in units of a length of 1 mm) ) Can be adjusted.

  The O-ring 11a is disposed in the groove 7b1 provided in the edge 7a2 of one opening 7a1 of the hole 7a of the base 7, and the O-ring 11b is the edge of the other opening 7a3 of the hole 7a of the base 7 Since it is disposed in the groove portion 7b2 provided in the portion 7a4, the O-ring 11a is disposed on the main surface F1 side of the base portion 7, and the O-ring 11b is disposed on the back surface F2 side of the base portion 7. The detector 1 is inserted into the hole 11a1 of the O-ring 11a, the hole 11b1 of the O-ring 11b, and the hole 7a of the base 7. Therefore, the detector 1 is sufficiently stably held by the base portion 7 due to friction between the outer surface of the detector 1 and the O-ring 11a and the O-ring 11b, and the direction intersecting the main surface F1 of the base portion 7 ( In the direction in which the hole 7a of the base portion 7 into which the detector 1 is inserted), the position of the tip 1b of the detector 1, that is, the position of the magnetic sensor element 1a can be adjusted with relatively high accuracy.

  Note that the magnetic measurement device 100 may include a base portion 71 shown in FIG. 4B instead of the base portion 7 shown in FIG. The base portion 71 is different from the base portion 7 in the configuration of the position adjusting portion (O-ring and hole), but the other configuration of the base portion 71 is the same as the base portion 7. The material of the base portion 71 (including the coating material) is also the same as that of the base portion 7. The position adjustment unit of the base unit 71 shown in FIG. 4B has one O-ring, that is, an O-ring 11c. The base portion 71 is provided with a hole portion 71a penetrating from the main surface F3 to the back surface F4 of the base portion 71. One detector 1 is inserted into one hole 71a. The tip 1b of the detector 1 is on the back surface F4 of the base 71, and the other end of the detector 1 is on the main surface F3 of the base 71. The hole 11c1 of the O-ring 11c of the position adjusting unit and the hole 71a of the base 71 are in communication. The detector 1 is in contact with the O-ring 11 c and is inserted into the hole 11 c 1 of the O-ring 11 c and the hole 71 a of the base 71. The shape of the side surface 71b of the hole portion 71a of the base portion 71 is adapted to the shape of the O-ring 11c, and the O-ring 11c can be stably accommodated in the hole portion 71a. Due to such a shape of the side surface 71b, even if the detector 1 inserted into the hole 11c1 is moved, the O-ring 11c comes out (disengages) from the hole 71a in accordance with the movement of the detector 1. The probability of occurrence is relatively low.

  The main surface F3 and the back surface F4 of the helmet-shaped base portion 71 are arranged along the surface of the magnetic measurement target, and the magnetic sensor element 1a of the tip portion 1b of the detector 1 mounted on the base portion 71 is measured. Since the surface can be sufficiently close to the surface, a relatively strong magnetic field can be measured from the measurement target.

  Since the detector 1 is in contact with the O-ring 11c of the position adjustment unit of the base 71 and is inserted into the hole 11c1 of the O-ring 11c and the hole 71a of the base 71, the detector 1 and the O-ring 11c. The detector 1 is stably held by the base portion 71 and the direction intersecting the main surface F3 of the base portion 71 (the extension of the hole portion 71a of the base portion 71 into which the detector 1 is inserted). The position of the tip 1b of the detector 1, that is, the position of the magnetic sensor element 1a, can be adjusted with sufficient accuracy (for example, in units of a length of 1 mm).

  The magnetic measurement device 100 may include a base portion 72 shown in FIGS. 5 and 6 instead of the base portion 7 shown in FIG. The base portion 72 is different from the base portion 7 in the configuration of the position adjusting portion (O-ring and hole), but the other configuration of the base portion 72 is the same as the base portion 7. The material of the base portion 72 (including the coating material) is also the same as that of the base portion 7. The position adjusting portion of the base portion 72 includes a protruding portion 13, a cap portion 15, and an O-ring 11d. The protruding portion 13 is provided on the main surface F5 of the base portion 72 and has a cylindrical shape extending on the main surface F5. The cap portion 15 is screwed into the protruding portion 13. The O-ring 11 d is provided between the end surface 13 c of the protruding portion 13 and the cap portion 15. The protruding portion 13 and the cap portion 15 are screwed together with the O-ring 11d interposed therebetween. The base portion 72 is provided with a hole portion 72a penetrating from the main surface F5 to the back surface F6 of the base portion 72. The protruding portion 13 has a side wall 13b extending on the main surface F5. A thread groove is formed on the outer surface of the side wall 13 b of the protruding portion 13. The cap part 15 has a side wall 15a and a bottom wall 15b extending in a direction intersecting the side wall 15a. On the inner surface of the side wall 15a of the cap portion 15, a thread groove that can be screwed with the protruding portion 13 is formed. The bottom wall 15b of the protruding portion 13 is provided with a hole 15c that penetrates the bottom wall 15b. The hole 15c in the bottom wall 15b of the cap part 15, the hole 11d1 in the O-ring 11d, the cylindrical hole 13a in the projecting part 13, and the hole 72a in the base part 72 are in communication. The detector 1 is in contact with the O-ring 11d, the hole 15c of the bottom wall 15b of the cap part 15, the hole 11d1 of the O-ring 11d, the cylindrical hole 13a of the protruding part 13, and the hole 72a of the base part 72, Inserted into. The O-ring 11 d is sandwiched between the end surface 13 c of the protruding portion 13 and the bottom wall 15 b of the cap portion 15. The material of the protruding portion 13 can be the same material as that of the base portion 72. However, when the base portion 72 is made of pure aluminum, the protruding portion using a hard material such as brass can be used for durability. Can be given. The material of the cap portion 15 can be not only a material having a magnetic shielding effect but also a resin or the like, but is the same as the material of the protruding portion 13 in this embodiment.

  According to the configuration of the position adjustment portion of the base portion 72, the hole portion 72 a of the base portion 72, the cylindrical hole 13 a of the protruding portion 13, the hole portion 11 d 1 of the O-ring 11 d, and the hole portion 15 c of the bottom wall 15 b of the cap portion 15. Since the detector 1 is inserted into the base portion 72, the detector 1 is stably held by the base portion 72. In addition, since the cap portion 15 is screwed into the protruding portion 13 in a state where the O ring 11d is sandwiched between the bottom wall 15b of the cap portion 15 and the end surface 13c of the protruding portion 13, the O ring 11d The bottom wall 15b of the 15 and the end face 13c of the protrusion 13 are crushed and deformed, and the diameter of the hole 11d1 of the O-ring 11d becomes relatively small. For this reason, the friction between the detector 1 inserted into the hole 11d1 of the deformed O-ring 11d and the O-ring 11d becomes relatively large, so that the detector 1 is attached to the base 72 in a more stable state. Retained. In the direction intersecting the main surface F5 of the base portion 72 (the direction in which the hole portion 72a of the base portion 72 into which the detector 1 is inserted extends), the position of the tip portion 1b of the detector 1, that is, the magnetic sensor element 1a is Adjustment can be made with sufficient accuracy (for example, in units of a length of 1 mm).

  With reference to FIG. 7, the structure of the front-end | tip part of the detector 1 is demonstrated. The magnetic sensor element 1a includes a fixture 1c, a coil 1d, a covering portion 1e, a conductor portion 1f, a coil 1g, a conductor portion 1h, a waveguide portion 1i, an insulating portion 1j, an insulating portion 1k, an outer skin portion 1m, a magnetic shielding portion 1n, It has an O-ring 1p and a spacer portion 1q. The conductor portion 1f, the conductor portion 1h, the waveguide portion 1i, the insulating portion 1j, the insulating portion 1k, the outer skin portion 1m, and the spacer portion 1q extend from the distal end portion 1b of the magnetic sensor element 1a to the other end of the magnetic sensor element 1a. The spacer part 1q is provided on the waveguide part 1i, the insulating part 1j is provided on the spacer part 1q, the conductor part 1h is provided on the insulating part 1j, and the insulating part 1k is provided on the conductor part 1h. The conductor portion 1f is provided on the insulating portion 1k, and the outer skin portion 1m is provided on the conductor portion 1f. The outer skin portion 1m has high insulating properties, like the insulating portion 1j and the insulating portion 1k. The covering portion 1e covers the end surface of the tip portion 1b.

  The magnetic sensor element 1 a is provided at the tip 1 b of the detector 1. The fixture 1c stably fixes the magnetic sensor element 1a to the tip 1b. The end face of the waveguide 1i is in stable contact with the magnetic sensor element 1a by an O-ring 1p. The waveguide 1i guides green light (wavelength 532 nm) guided from the optical fiber K2 to the magnetic sensor element 1a, and further transmits red light (wavelength 637 nm) emitted from the magnetic sensor element 1a to the optical fiber K2. Waveguide. The coil 1g is a Helmholtz coil, and is provided on one surface of the magnetic sensor element 1a (the surface in contact with the waveguide 1i) (in other words, so as to wind the end of the waveguide 1i). Yes. The coil 1g is connected to a conductor (conductive wire) included in the conductor portion 1h, and this conductor is connected to the electric cable K1. The conductor portion 1h includes another conductor (conductive wire) different from the conductor connected to the coil 1g. The other conductor is connected to the magnetic sensor element 1a. A metal wiring pattern is directly provided on the surface of the magnetic sensor element 1a, and the other conductors are connected to the metal wiring pattern. The conductor connected to the coil 1g and the conductor connected to the magnetic sensor element 1a are both included in the conductor portion 1h, but are insulated from each other. The electric cable K1 is composed of three conductors insulated from each other, and each of the two conductors is a conductor of the conductor part 1h connected to the coil 1g and a conductor part connected to the magnetic sensor element 1a. It is connected to the 1h conductor. That is, one conductor of the electric cable K1 is connected to the conductor of the conductor portion 1h connected to the coil 1g, and the other conductor of the electric cable K1 is a conductor of the conductor portion 1h connected to the magnetic sensor element 1a. It is connected to the.

  The coil 1d is a Helmholtz coil, and is provided on the other surface of the magnetic sensor element 1a (the surface opposite to the surface in contact with the waveguide 1i). The coil 1d is connected to a conductor (conductive wire) included in the conductor portion 1f, and this conductor is connected to one of the three conductive wires included in the electric cable K1. The conducting wire of the electric cable K1 connected to the conductor included in the conductor portion 1f is insulated from the other two conducting wires of the electric cable K1. Of the other two conducting wires of the electric cable K1, one conducting wire is connected to the coil 1g and the other conducting wire is connected to the magnetic sensor element 1a.

  The magnetic shield 1n covers the tip 1b including the magnetic sensor element 1a. The magnetic shielding part 1n is, for example, permalloy.

  The material of the fixture 1c can be, for example, an aluminum alloy. In this case, a permalloy coating can be applied to the surface of the aluminum alloy. The material of the fixture 1c can be, for example, plastic. In this case, the surface of plastic or the like can be coated with aluminum or permalloy. The material of the fixture 1c (including the coating material) can be a material having a magnetic shielding effect, such as silver, copper, gold, brass, and nickel. As the material of the coil 1d, metals such as copper and nickel, or Teflon (registered trademark) and rubber can be used. In the present embodiment, a rubber ring is used for the coil 1d.

  As the material of the covering portion 1e, when the central portion of the covering portion 1e is blocked, a resin such as acrylic, a nonmagnetic crystal such as sapphire, or the like can be used. Moreover, when the hole for exposing the magnetic sensor element 1a is provided in the center part of the coating | coated part 1e, an aluminum alloy etc. can be used for the material of the coating | coated part 1e, for example. Thus, when the aluminum alloy is used for the material, the surface of the aluminum alloy can be coated with permalloy. In the case where a hole for exposing the magnetic sensor element 1a is provided in the central portion of the covering portion 1e, for example, plastic or the like can be used as the material of the covering portion 1e. When plastic is used as a material in this way, the surface of the plastic can be coated with aluminum or permalloy. In addition, when the hole for exposing the magnetic sensor element 1a is provided in the center part of the coating | coated part 1e, silver, copper, gold | metal | money, brass, as the material (including the coating material) of the coating | coated part 1e A material having a magnetic shielding effect such as nickel can be used.

  The material of the conductor portion 1f can be, for example, an aluminum alloy. In this case, a permalloy coating can be applied to the surface of the aluminum alloy. The material of the conductor portion 1f can be, for example, plastic. In this case, the surface of plastic or the like can be coated with aluminum or permalloy. Note that the material (including the coating material) of the conductor portion 1f may be a material having a magnetic shielding effect, such as silver, copper, gold, brass, or nickel. As a material of the coil 1g, a conductor having a low electric resistance such as copper can be used. As the material of the conductor portion 1h, a conductor having a low electric resistance such as copper can be used. As the material of the waveguide 1i, quartz or a polymer material used for an optical fiber can be used. As the material of the insulating portion 1j, an insulating material, for example, a fluorine-based resin such as Teflon resin (Teflon: registered trademark) or a resin such as acrylic can be used. As a material of the insulating portion 1k, an insulating material, for example, a fluorine resin such as Teflon resin (Teflon: registered trademark) or a resin such as acrylic can be used.

  The material of the outer skin portion 1m can be, for example, an aluminum alloy. In this case, a permalloy coating can be applied to the surface of the aluminum alloy. The material of the outer skin portion 1m can be, for example, plastic. In this case, the surface of plastic or the like can be coated with aluminum or permalloy. The material (including the coating material) of the outer skin portion 1m can be a material having a magnetic shielding effect, such as silver, copper, gold, brass, and nickel. The material of the magnetic shielding part 1n can be, for example, an aluminum alloy. In this case, a permalloy coating can be applied to the surface of the aluminum alloy. The material of the magnetic shield 1n can be, for example, plastic. In this case, the surface of plastic or the like can be coated with aluminum or permalloy. The material of the magnetic shielding part 1n (including the coating material) can be a material having a magnetic shielding effect such as silver, copper, gold, brass and nickel. An insulator is used as the material of the spacer portion 1q.

  The control device 5 supplies a current to each of the coil 1d and the coil 1g, generates a static magnetic field, generates a microwave, or generates a μ wave. For example, the control device 5 calibrates the magnetic field around the magnetic sensor element 1a by generating a static magnetic field in the coil 1g and generating a microwave in the coil 1d. The control device 5 calibrates the magnetic field around the magnetic sensor element 1a by, for example, generating a μ wave in the coil 1g and generating a static magnetic field in the coil 1d. For example, the control device 5 calibrates the magnetic field around the magnetic sensor element 1a by generating a static magnetic field in the coil 1g and generating a static magnetic field in the coil 1d. For example, the control device 5 measures the magnetic field by generating a microwave in the coil 1g and not supplying a current to the coil 1d. For example, the control device 5 does not supply current to the coil 1g and measures a magnetic field by generating a microwave in the coil 1d. The control device 5 performs, for example, simultaneous measurement of two wavelengths by generating a microwave in the coil 1g and generating a microwave in the coil 1d (S = 0 and S = ± 1 (“S” is a spin). Two types of microwaves corresponding to each of the resonance frequency between the angular frequency and the resonance frequency between S = + 1 and S = −1 (“S” is the spin angular momentum), or alternately and simultaneously. In particular, when two types of microwaves corresponding to the two resonance frequencies are simultaneously applied to the magnetic sensor element 1a, the change in the signal is emphasized. The change is experimentally emphasized about twice as a differential value, and the S / N ratio may be slightly higher.)

Next, with reference to Fig.8 (a), the manufacturing method of the magnetic sensor element 1a which concerns on embodiment is demonstrated. First, a single crystal diamond containing ¹³ C atoms with an atomic concentration of 0.01% or less, nitrogen atoms with an atomic concentration of 0.1 ppm or less, and boron atoms with an atomic concentration of less than 1 ppm is prepared (step S1). Next, ions of nitrogen atoms are implanted into the single crystal diamond at an energy of 10 keV to 3 MeV and an atomic concentration of 1 × 10 ¹³ / cm ^{−2 to} 1 × 10 ²⁰ / cm ⁻² (step S2). ). Next, the single crystal diamond after the ion implantation is heated at a temperature in the range of 600 degrees Celsius or more and 1400 degrees Celsius or less within a time period of 1 hour or more and 3 hours or less (step S3). After the steps S1 to S3, the outer shape of the single crystal diamond is adjusted to manufacture the magnetic sensor element 1a.

According to the method for manufacturing the magnetic sensor element shown in FIG. 8A, since the atomic concentration of ¹³ C atoms is 0.01% or less, the electrical and optical heat generation generated in the magnetic sensor element 1a is sufficiently reduced. The According to the method for manufacturing the magnetic sensor element shown in FIG. 8A, the atomic concentration of boron atoms is extremely low, so that the magnetic sensor element 1a has sufficient insulation. Therefore, it is possible to directly form a coil by metal wiring on the magnetic sensor element 1a.

According to the manufacturing method of the magnetic sensor element shown in FIG. 8A, an energy of 10 keV to 3 MeV and an atomic concentration of 1 × 10 ¹³ / cm ^{−2 to} 1 × 10 ²⁰ / cm ⁻² are used. Ions of nitrogen atoms are implanted into the crystal diamond, and then the single crystal diamond after the ion implantation is heated at a temperature in the range of 600 degrees Celsius to 1400 degrees Celsius within a period of 1 hour to 3 hours. To do. By performing such ion implantation and heating, the atomic concentration of nitrogen atoms in the single crystal diamond is 100 ppm or less, and the nitrogen atoms adjacent to the vacancies are 5% or more of the nitrogen atoms contained in the single crystal diamond. It becomes. Therefore, since the generation of a minute magnetic field that suppresses the spin-spin relaxation time by ESR detection is reduced, sufficient magnetic detection sensitivity can be obtained.

In addition, the magnetic sensor element 1a can also be manufactured according to the process shown in FIG.8 (b). With reference to FIG.8 (b), the other manufacturing method of the magnetic sensor element 1a which concerns on embodiment is demonstrated. First, a single crystal diamond containing ¹³ C atoms having an atomic concentration of 0.01% or less, nitrogen atoms having an atomic concentration of more than 0.1 ppm, and boron atoms having an atomic concentration of less than 1 ppm is prepared (step S4). Next, the single crystal diamond is irradiated with an electron beam at an energy of 0.7 MeV to 10 MeV and an irradiation dose of 1 Gy to 1 GGy (step S5). Next, the single crystal diamond after the electron beam irradiation is heated at a temperature in the range of 600 degrees Celsius or more and 1400 degrees Celsius or less within a period of 3 hours or more and 4 hours or less (step S6). After the steps S4 to S6, the outer shape of the single crystal diamond is adjusted to manufacture the magnetic sensor element 1a.

According to the method for manufacturing the magnetic sensor element shown in FIG. 8B, since the atomic concentration of ¹³ C atoms is 0.01% or less, the electrical and optical heat generated in the magnetic sensor element 1a is sufficiently reduced. The

  According to the method for manufacturing a magnetic sensor element shown in FIG. 8B, the atomic concentration of boron atoms is extremely low, so that the magnetic sensor element 1a has sufficient insulation. Therefore, it is possible to directly form a coil by metal wiring on the magnetic sensor element 1a.

  According to the method for manufacturing a magnetic sensor element shown in FIG. 8 (b), single crystal diamond is irradiated with an electron beam at an energy of 0.7 MeV to 10 MeV and an irradiation dose of 1 Gy to 1 GGy. The single crystal diamond after the electron beam irradiation is heated at a temperature in the range of 600 degrees Celsius or more and 1400 degrees Celsius or less within a time period of 4 hours or more. By performing such electron beam irradiation and heating, the atomic concentration of nitrogen atoms in the single crystal diamond is 100 ppm or less, and the nitrogen atoms adjacent to the vacancy are 5 nitrogen atoms contained in the single crystal diamond. % Or more. Therefore, generation of a minute magnetic field for suppressing ESR is reduced, and sufficient magnetic detection sensitivity can be obtained. In addition, since single crystal diamond containing nitrogen atoms having an atomic concentration of 0.1 ppm or more is used, the magnetic sensor element 1a can be manufactured at a lower cost than when ion implantation is used. That is, in order to uniformly implant ions in the depth direction of the crystal thickness in ion implantation, it is necessary to implant a plurality of times while changing the acceleration voltage. If the electron beam irradiation is performed using single crystal diamond containing nitrogen atoms having the atomic concentration of 1, the magnetic sensor element 1a can be manufactured at a lower cost.

(Example 1) In synthesizing a diamond single crystal, first, polycrystalline diamond prepared by vapor phase synthesis on a silicon substrate was used as a carbon supply source. For the gas phase synthesis, methane gas having a ¹³ C abundance in the constituent carbon of 0.01% was used. The polycrystalline diamond synthesized on the silicon substrate was obtained by removing the silicon substrate with hydrofluoric acid and weighed 2 carats. Next, high-temperature and high-pressure synthetic diamond was prepared using this carbon source. In the high-temperature and high-pressure synthesis, known diamond synthesis conditions of 5.5 GPa and 1350 degrees Celsius were used, and a solvent mixed with an Al-based titanium getter was used. Thus, a diamond piece having an outer shape of about 3 mm × 3 mm × 1 mm was cut out from the synthesized diamond. Impurity nitrogen was 0.1 ppm or less. The boron concentration was 0.0001 ppm. This diamond piece was irradiated with nitrogen ions at ² MeV and 10 ¹⁸ cm ⁻² and annealed in vacuum (1 × 10 ⁻² Pa) at 800 degrees Celsius. Corresponding absorption at 570 nm and zero phonon absorption at 638 nm could be observed. A detector was made using the magnetic sensor element made of this diamond piece, and a flexible magnetic measuring device was made using this detector. The base part has a helmet-like structure, and 20 detectors are attached to the base part. When only the detector was made movable, the distance between the magnetic sensor element provided at the tip of the detector and the head skin could be reduced to about 1 mm. When permalloy was used for the magnetic shield and magnetism was measured with NMR pulses, magnetism of 10 nT or more could be measured (magnetic detection sensitivity was 10 nT). The magnetic detection sensitivity could be further increased by performing sufficient shielding. Furthermore, instead of the helmet-shaped base portion, a base portion having a neck-shaped depression so as to surround the spine was used, and 20 detectors were attached to this base portion. When only the detector was made movable, the distance between the skin of the neck and the magnetic sensor element provided at the tip of the detector could be reduced to about 1 mm. When permalloy was used for the magnetic shield and magnetism was measured with an ESR pulse, magnetism of 10 nT or more could be measured. The magnetic detection sensitivity could be further increased by performing sufficient shielding.

(Example 2) In synthesizing a diamond single crystal, first, polycrystalline diamond prepared by vapor phase synthesis on a silicon substrate was used as a carbon supply source. For the gas phase synthesis, methane gas having a ¹³ C abundance in the constituent carbon of 0.01% was used. The polycrystalline diamond synthesized on the silicon substrate was obtained by removing the silicon substrate with hydrofluoric acid and weighed 2 carats. Next, high-temperature and high-pressure synthetic diamond was prepared using this carbon source. In the high-temperature and high-pressure synthesis, known diamond synthesis conditions of 5.5 GPa and 1350 degrees Celsius were used, and a solvent mixed with an Al-based titanium getter was used. Thus, a diamond piece having an outer shape of about 3 mm × 3 mm × 1 mm was cut out from the synthesized diamond. Impurity nitrogen was 0.1 ppm or less. The boron concentration was 0.0001 ppm. This diamond piece was irradiated with an electron beam at a dose of 2 MeV and 100 Gy, and annealed in vacuum (1 × 10 ⁻² Pa) at 800 ° C. From the light absorption spectrum, the NV center An absorption at 570 nm and zero phonon absorption at 638 nm could be observed. A detector was made using the magnetic sensor element made of this diamond piece, and a flexible magnetic measuring device was made using this detector. The base part has a helmet-like structure, and 20 detectors are attached to the base part. When only the detector was movable, the distance between the magnetic sensor element provided at the tip of the detector and the head skin could be reduced to about 1 mm. When permalloy was used for the magnetic shield and magnetism was measured with an NMR pulse, magnetism of 10 nT or more was measured. The magnetic detection sensitivity could be further increased by performing sufficient shielding. Furthermore, instead of the helmet-shaped base portion, a base portion having a neck-shaped depression so as to surround the spine was used, and 20 detectors were attached to this base portion. When only the detector was made movable, the distance between the skin of the neck and the magnetic sensor element provided at the tip of the detector could be reduced to about 1 mm. When permalloy was used for the magnetic shield and magnetism was measured by pulse ESR, magnetism of 10 nT or more could be measured. The magnetic detection sensitivity could be further increased by performing sufficient shielding.

  While the principles of the invention have been illustrated and described in the preferred embodiments, it will be appreciated by those skilled in the art that the invention can be modified in arrangement and detail without departing from such principles. The present invention is not limited to the specific configuration disclosed in the present embodiment. We therefore claim all modifications and changes that come within the scope and spirit of the following claims.

  DESCRIPTION OF SYMBOLS 1 ... Detector, 100 ... Magnetic measuring device, 11 ... Arm, 11a, 11b, 11c, 11d, 1p ... O-ring, 11a1, 11b1, 11c1, 11d1, 15c, 71a, 72a, 7a, 9a ... Hole part, 13 ... Projection, 13a ... Tube hole, 13b, 15a ... Side wall, 13c ... End face, 15 ... Cap part, 15b ... Bottom wall, 1a ... Magnetic sensor element, 1b ... Tip part, 1c ... Fixing tool, 1d, 1g ... Coil DESCRIPTION OF SYMBOLS 1e ... Cover part, 1f ... Conductor part, 1h ... Conductor part, 1i ... Waveguide part, 1j, 1k ... Insulating part, 1m ... Outer skin part, 1n ... Magnetic shielding part, 1q ... Spacer part, 3 ... Optical transmission / reception unit , 31: Optical transmission / reception unit group, 3a: Oscillation device, 3b: Optical transmission device, 3c ... Optical reception device, 5 ... Control device, 7, 71, 72 ... Base portion, 71b ... Side surface, 7a1, 7a3 ... Opening, 7a2 7a4 ... edge 7b1 and 7b2 ... groove, 9 ... support device, F1, F3, F5 ... main surface, F2, F4, F6 ... rear surface, K ... cable, K1 ... electric cable, K2 ... optical fiber

Claims (7)

A detector for detecting magnetism using electron spin resonance;
A base portion on which the detector is mounted;
A magnetic measuring device comprising:
The detector has a magnetic sensor element provided at the tip of the detector,
The magnetic sensor element is made of diamond that outputs an electron spin resonance signal,
The diamond of the magnetic sensor element includes ¹³ C atoms having an atomic concentration of 0.01% or less and nitrogen atoms having an atomic concentration of 100 ppm or less,
The number of nitrogen atoms contained in diamond of the magnetic sensor element and adjacent to vacancies in diamond of the magnetic sensor element is 5% or more of the number of nitrogen atoms contained in diamond of the magnetic sensor element. And
The base portion has a main surface, and has a position adjustment portion for adjusting the position of the tip portion in a direction intersecting the main surface.
Magnetic measuring device characterized by that.   The magnetic measurement apparatus according to claim 1, wherein the atomic concentration of boron atoms contained in diamond of the magnetic sensor element is less than 1 ppm. The base portion is provided with a hole penetrating from the main surface to the back surface of the base portion,
The position adjusting unit has one or a plurality of O-rings,
The hole of the one or more O-rings communicates with the hole of the base,
2. The detector according to claim 1, wherein the detector is inserted into a hole portion of the one or the plurality of O-rings and a hole portion of the base portion in contact with the one or the plurality of O-rings. 2. The magnetic measuring device according to 2. The base portion has two groove portions provided at the respective edge portions of the two openings of the hole portion of the base portion,
The position adjusting unit has two O-rings,
One O-ring of the two O-rings is disposed in one of the two grooves, and the other O-ring of the two O-rings is the other of the two grooves. The magnetic measuring device according to claim 3, wherein the magnetic measuring device is disposed in a groove portion of the magnetic field. The position adjusting unit is
A cylindrical protrusion provided on the main surface and extending on the main surface;
A cap portion screwed into the protruding portion;
An O-ring provided between the end surface of the protruding portion and the cap portion;
Have
The protruding portion and the cap portion are screwed together with the O-ring sandwiched therebetween,
The base portion is provided with a hole penetrating from the main surface to the back surface of the base portion,
The protrusion has a side wall extending on the main surface,
A thread groove is formed on the outer surface of the side wall of the protrusion,
The cap portion has a side wall and a bottom wall extending in a direction intersecting the side wall,
On the inner surface of the side wall of the cap portion, a thread groove that can be screwed with the protruding portion is formed,
The bottom wall of the cap part is provided with a hole that penetrates the bottom wall,
The hole part of the bottom wall of the cap part, the hole part of the O-ring, the cylindrical hole of the projecting part, and the hole part of the base part communicate with each other.
The detector is inserted into the hole of the bottom wall of the cap part, the hole part of the O-ring, the cylindrical hole of the projecting part, and the hole part of the base part in contact with the O-ring,
The magnetic measuring apparatus according to claim 1, wherein the O-ring is sandwiched between an end surface of the protruding portion and a bottom wall of the cap portion. A method for manufacturing a magnetic sensor element included in the magnetic measurement device according to any one of claims 1 to 5,
Providing a single crystal diamond comprising ¹³ C atoms with an atomic concentration of 0.01% or less, nitrogen atoms with an atomic concentration of 0.1 ppm or less, and boron atoms with an atomic concentration of less than 1 ppm;
Implanting nitrogen atom ions into the single crystal diamond at an energy of 10 keV to 3 MeV and an atomic concentration of 1 × 10 ¹³ / cm ^{−2 to} 1 × 10 ²⁰ / cm ⁻² ;
Heating the single crystal diamond after the ion implantation at a temperature in the range of 600 degrees Celsius or more and 1400 degrees Celsius or less within a time period of 1 hour or more and 3 hours or less;
A method of manufacturing a magnetic sensor element, comprising: A method for manufacturing a magnetic sensor element included in the magnetic measurement device according to any one of claims 1 to 5,
Providing a single crystal diamond comprising ¹³ C atoms with an atomic concentration of 0.01% or less, nitrogen atoms with an atomic concentration of greater than 0.1 ppm, and boron atoms with an atomic concentration of less than 1 ppm;
Irradiating the single crystal diamond with an electron beam at an energy of 0.7 MeV to 10 MeV and an irradiation dose of 1 Gy to 1 GGy;
Heating the single crystal diamond after the electron beam irradiation at a temperature in the range of 600 degrees Celsius or more and 1400 degrees Celsius or less within a period of 3 hours or more and 4 hours or less;
A method of manufacturing a magnetic sensor element, comprising:

Images