Diamond spin sensor and device equipped with diamond spin sensor

Abstract

The diamond spin sensor includes: a diamond having a color center with electron spins; and an optical waveguide that transmits the excitation light irradiated to the diamond and the fluorescence emitted from the diamond, and measures a magnetic field, an electric field, or a temperature in an environment through a color center in a state in which the diamond is disposed in the environment in which radiation is present at 1 [mu] Gy / h or more.

Description

Technical Field

[0001] This disclosure relates to diamond spin sensors and devices equipped with diamond spin sensors. This application claims priority based on Japanese Application No. 2023-067531, filed on April 18, 2023, and invokes the entire contents of that Japanese application. Background Technology

[0002] Sensors are known for measuring magnetic fields, electric fields, currents, voltages, or temperatures. For example, Hall effect elements or TMR (tunneling magnetoresistive) elements are used as sensors for measuring magnetic fields. Thermocouples are used as sensors for measuring temperature. In these sensors, metal wiring is connected to the part being detected, and this wiring is typically covered with resin. If such sensors are used in an environment with intersecting X-rays or electron beams, ionization caused by the X-rays or electron beams generates noise in the metal wiring that transmits the electrical signal from the sensor, and the resin covering deteriorates due to the X-rays or electron beams. Therefore, these sensors are essentially unusable in environments with intersecting X-rays or electron beams.

[0003] Diamond spin sensors, which utilize NV centers (hereinafter referred to as NV centers) in diamond and can be used in environments with X-ray or electron beam crosstalk, are known. If the NV center, formed by nitrogen at a carbon substitution site in diamond and the adjacent pore, is negatively charged, its substrate state becomes a triplet state (i.e., spin S = S=1). When the NV center is excited with light at a wavelength of 532 nm (i.e., green light), it emits fluorescence at a wavelength of 637 nm (i.e., red light). The intensity of the fluorescence varies depending on the spin state, and since the spin state varies according to the magnetic resonance induced by the magnetic field applied to the NV center and microwave or radio waves, it can be used as a magnetic sensor.

[0004] For example, a diamond spin sensor comprises a diamond substrate containing an NV center, an optical system that transmits excitation light from a light source to irradiate the NV center, an optical system that focuses fluorescence from the NV center to transmit it to a photodetector, and a waveguide that transmits microwaves from a power source to irradiate the NV center. For example, Non-Patent Document 1 discloses a structure in which a diamond sensor is mounted on a coplanar waveguide and microwaves are irradiated. The diamond substrate is cuboid in shape, the excitation light is irradiated laterally from the diamond substrate, and the fluorescence is focused from above the diamond substrate.

[0005] Existing technical documents Non-patent literature Non-Patent Document 1: Yuta Masuyama, Yuji Hatano, Takayuki Iwasaki, Mutsuko Hatano, “High-Sensitivity Microdiamond Magnetometer Using Coplanar Waveguides”, Proceedings of the 79th Autumn Academic Conference of the Chinese Society of Applied Physics (Published: September 5, 2018) Non-patent literature 2: MW Doherty, VM Acosta, A. Jarmola, MSJ Barson, NB Manson, D. Budker, and LCL Hollenberg, "Temperature shifts of theresonances of the NV-center in diamond", PHYSICAL REVIEW B 90, 041201 (R) (2014) Summary of the Invention One aspect of this disclosure relates to a diamond spin sensor comprising: a diamond having a color center with electron spin; and an optical waveguide for transmitting excitation light irradiated onto the diamond and fluorescence emitted from the diamond, wherein the color center measures a magnetic field, an electric field, or a temperature in the environment in which the diamond is disposed in an environment with radiation of 1 μGy / h or higher. Attached Figure Description

[0006] Figure 1 This is a schematic diagram illustrating the configuration of a device using the diamond spin sensor described in the first embodiment.

[0007] Figure 2 This is a block diagram showing the configuration of the apparatus used in the first embodiment.

[0008] Figure 3 It means to use Figure 2 The diagram shows the timing of the excitation light and electromagnetic wave irradiation, as well as the timing of the emission light measurement, during the measurement of the diamond spin sensor.

[0009] Figure 4 It is a graph that schematically shows the relationship between the observed signal strength (i.e., the intensity of emitted light) and the frequency of electromagnetic waves (i.e., microwaves).

[0010] Figure 5 This is a schematic diagram illustrating the configuration of an X-ray generating apparatus using the diamond spin sensor according to the second embodiment.

[0011] Figure 6 This is a vertical cross-sectional view showing the configuration of an electron beam irradiation apparatus using the diamond spin sensor according to the third embodiment.

[0012] Figure 7 This is a vertical cross-sectional view showing the configuration of the diamond spin sensor according to the third embodiment.

[0013] Figure 8 It is a three-dimensional diagram showing the structure of the shielding components.

[0014] Figure 9 It means and Figure 8 A three-dimensional diagram showing the composition of different shielding components.

[0015] Figure 10 This is a cross-sectional view showing the configuration of the diamond spin sensor according to the fourth embodiment.

[0016] Figure 11 This is a cross-sectional view showing the configuration of the diamond spin sensor according to the fifth embodiment. Detailed Implementation

[0017] The problem this disclosure aims to solve In diamond spin sensors, optical fibers are used as waveguides for both excitation light and fluorescence. Even when used in environments with intersecting X-rays or electron beams, they are not affected by electrical noise. However, there is a problem that the optical waveguide (i.e., the optical fiber) deteriorates due to X-rays or electron beams.

[0018] Therefore, the purpose of this disclosure is to provide a diamond spin sensor that can be used in an environment with X-rays or electron beams interleaved, and an apparatus equipped with a diamond spin sensor.

[0019] The effect of this disclosure According to this disclosure, a diamond spin sensor capable of being used in an environment with interleaved X-rays or electron beams, and an apparatus equipped with a diamond spin sensor, can be provided.

[0020] Description of embodiments of this disclosure The embodiments of this disclosure are described in detail below. At least some of the embodiments described below may be combined in any way.

[0021] (1) The diamond spin sensor according to the first aspect of this disclosure comprises: a diamond having a color center with electron spin; and an optical waveguide for transmitting excitation light irradiated to the diamond and fluorescence emitted from the diamond. When the diamond is placed in an environment with radiation levels of 1 μGy / h or higher, the magnetic field, electric field, or temperature in the environment is measured via the color center. Thus, a diamond spin sensor and a device equipped with a diamond spin sensor can be provided that can be used in an environment with alternating X-rays or electron beams. That is, measurements can be performed in environments with radiation levels of 1 μGy / h or higher, which were previously difficult to measure.

[0022] (2) In (1) above, the diamond spin sensor may further include: an excitation light irradiation section for irradiating the diamond with excitation light; and a fluorescence collection section for collecting fluorescence emitted from the diamond. The optical waveguide, the excitation light irradiation section, and the fluorescence collection section may be disposed in a position not exposed to radiation. Thus, the degradation of the optical waveguide (e.g., optical fiber) can be suppressed, and the excitation light irradiation section and the fluorescence collection section can be prevented from being affected by X-rays or electron beams.

[0023] (3) In (2) above, the optical waveguide can also be an optical fiber, and the diamond spin sensor can further include a metal component that blocks radiation with an energy of more than a predetermined value. The metal component can also cover the optical fiber or be disposed around the optical fiber in such a way that the optical fiber is not exposed to radiation of more than 1 μGy / h. The radiation can also include X-rays or electron beams. Thus, the degradation of the optical fiber can be reliably suppressed.

[0024] (4) In (3) above, the diamond can also be exposed from the metal component. As a result, magnetic fields, electric fields and temperature can be measured with high sensitivity.

[0025] (5) In (3) or (4) above, the metal component may also include a cylindrical first shielding portion, the optical fiber may also have an output end for outputting excitation light, and the optical fiber may also be configured to pass through the first shielding portion and accommodate the output end in the first shielding portion. Thus, the degradation of the optical fiber can be suppressed more reliably.

[0026] (6) In (5) above, the metal component may further include a second shielding portion and a third shielding portion, which may be spaced apart from each other by a predetermined interval and joined to the end of the first shielding portion. Thus, the magnetic field formed by charged particles (e.g., electrons) moving along the direction in which the second shielding portion and the third shielding portion are separated can be measured with high precision.

[0027] (7) In (6) above, the diamond spin sensor may further include an optical element housed in the first shielding portion, and the diamond may be disposed in the second and third shielding portions at the end opposite to the portion that is joined with the end of the first shielding portion. The optical element may also irradiate the diamond with excitation light output from the optical fiber. Thus, the optical fiber can be reliably prevented from being exposed to radiation, and the degradation of the optical fiber can be suppressed.

[0028] (8) In (7) above, the wall portions of the first shielding portion, the second shielding portion, and the third shielding portion that form the space for accommodating the diamond and the optical element can also be formed as mirrors. As a result, fluorescence emitted from the diamond can be efficiently input into the optical fiber.

[0029] (9) In any of (5) to (8) above, the diamond spin sensor may further include a reflective member housed in the first shielding portion, and the diamond may be separated from the reflective member and housed in the first shielding portion. The reflective member may also reflect the excitation light output from the optical fiber to irradiate the diamond. Thus, the optical fiber can be reliably prevented from being exposed to radiation, and the degradation of the optical fiber can be suppressed.

[0030] (10) In (9) above, the wall portion of the first shielding part that forms the space for accommodating the diamond and the reflective member can also be formed as a mirror. As a result, fluorescence emitted from the diamond can be efficiently input into the optical fiber.

[0031] (11) In any of (1) to (10) above, the nitrogen content in the diamond is 0.5 ppm or more and 300 ppm or less. Thus, the required accuracy of the physical quantities (magnetic field, electric field or temperature, etc.) observed by the diamond spin sensor can be met.

[0032] (12) In any of (1) to (11) above, the power density of the excitation light irradiating the diamond is 10 mW / mm². 2 Therefore, even if electrons are lost from the basal state of the diamond NV center due to radiation of 1 μGy / h or higher, a sufficient S / N ratio can be achieved in the measurement.

[0033] (13) The apparatus according to the second aspect of this disclosure is an apparatus equipped with a diamond spin sensor of any one of (2) to (10) above, wherein the optical waveguide, the excitation light irradiation unit, and the fluorescence collection unit are disposed outside the X-ray or electron beam generating apparatus or generating area. Thus, it is possible to provide an apparatus equipped with a diamond spin sensor that can be used in an environment where X-rays or electron beams are interleaved.

[0034] (14) In (13) above, the nitrogen content in the diamond is above 0.5 ppm and below 300 ppm. Therefore, the required accuracy of the observed physical quantity can be met.

[0035] (15) In (13) or (14) above, the power density of the excitation light irradiating the diamond is 10 mW / mm². 2 Therefore, even if electrons are lost from the basal state of the diamond NV center due to radiation of 1 μGy / h or higher, a sufficient S / N ratio can be achieved in the measurement.

[0036] (16) The apparatus according to the third aspect of this disclosure includes a diamond spin sensor of any one of (1) to (10) above, and the apparatus uses X-rays or an electron beam. Therefore, it is possible to measure magnetic fields, electric fields, and temperatures in an environment where X-rays or electron beams are interleaved. That is, it is possible to perform measurements in environments with radiation levels of 1 μGy / h or higher, which were previously difficult to measure. Similarly, it is possible to measure magnetic fields, electric fields, and temperatures in harsh radiation environments of 1 mGy / h or higher, further 1 Gy / h or higher, and further 1 kGy / h or higher.

[0037] Detailed description of the embodiments disclosed herein In the following embodiments, the same reference numerals are used to refer to the same parts. Their names and functions are also the same. Therefore, detailed descriptions of them will not be repeated.

[0038] (First Implementation) Reference Figure 1 The first embodiment of this disclosure discloses a diamond spin sensor comprising a diamond 100, an electromagnetic wave irradiation unit 102, and an optical device 104. The diamond 100 is diamond powder with a particle size of 1 μm to 3 μm containing NV centers, which is injected into a biological cell 900. Radiation 902 is irradiated into the biological cell 900 from a radiation generating device (not shown), such as an X-ray generating device or an electron beam generating device. The diamond spin sensor is used to observe the effects of radiation on the biological cell.

[0039] The electromagnetic wave irradiation unit 102 irradiates the diamond 100 with electromagnetic waves (e.g., microwaves). The electromagnetic wave irradiation unit 102 is, for example, a coil formed by including a conductor. Electromagnetic waves are supplied to the electromagnetic wave irradiation unit 102 via a resonator such as a λ / 4 open-circuit short wire made of copper foil and ceramic. Electromagnetic waves are supplied from a microwave generator via a coaxial cable at an intensity of, for example, 1mW or more.

[0040] The optical device 104 is, for example, a microscope, which irradiates the biological cells 900 with excitation light 106 transmitted from an electromagnetic wave irradiation unit (e.g., a light-emitting element) described later, and transmits the fluorescence 108 emitted from the diamond 100 to a light detection unit (detection device) described later. The excitation light 106 with an intensity of, for example, 0.3 mW or higher, is irradiated onto the diamond 100 through the optical device 104.

[0041] The irradiation of diamond 100 by excitation light 106 and the detection of fluorescence 108 emitted from diamond 100, for example, by... Figure 2The configuration shown is as described. The control unit 130 includes a CPU (Central Processing Unit) and a storage unit (neither shown). The processing performed by the control unit 130, which will be described later, is implemented by reading and executing programs pre-stored in the storage unit from the CPU.

[0042] The excitation light generating unit 110, controlled by the control unit 130, generates excitation light for exciting the NV center (hereinafter referred to as the NV center) of the diamond, described later. The control unit 130, for example, supplies a voltage to the excitation light generating unit 110 at a predetermined time to cause it to emit light. The excitation light is green light (i.e., wavelength 490-560 nm). The excitation light is preferably a laser, and the excitation light generating unit 110 is preferably a semiconductor laser (e.g., emitting light with a wavelength of 532 nm). The power density of the excitation light irradiating the NV center (diamond 100) of the diamond can also be 10 mW / mm². 2 Therefore, even if electrons are lost from the basal state of the diamond NV center due to radiation of 1 μGy / h or higher, a sufficient S / N ratio can be achieved in the measurement.

[0043] The filter 112 is an element used to separate the excitation light emitted from the excitation light generating section 110 from the light emitted from the diamond (i.e., fluorescence), which will be described later. For example, the filter 112 is a filter that blocks (i.e., reflects) light with wavelengths below a predetermined wavelength while allowing light with wavelengths larger than the predetermined wavelength to pass through, or a bandpass filter that allows light with wavelengths within a predetermined wavelength range to pass through while blocking (i.e., reflecting) light with wavelengths outside the predetermined wavelength range. Generally, since the excitation light has a shorter wavelength than the fluorescence, this configuration is preferred. The filter 112 is preferably a dichroic mirror with this function.

[0044] The focusing element 114 focuses the excitation light input from the filter 112. The focusing element 114 is, for example, a spherical lens. The focusing element 114 inputs as much of the excitation light diffused from the excitation light generating section 110 as possible into the end of the optical waveguide 116. The optical waveguide 116 contains a medium for transmitting light and transmits light in both directions. That is, the optical waveguide 116 has a first end and a second end, and transmits the excitation light incident on the first end to the second end located near the biological cell 900 containing diamond. In addition, the optical waveguide 116 transmits the emitted light (i.e., fluorescence) of the diamond incident on the second end and outputs it to the first end. The optical waveguide 116 is, for example, an optical fiber. Figure 2 Not shown, the excitation light output from the second end of the optical waveguide 116 passes through... Figure 1 The optical device 104 shown (e.g., a microscope) illuminates the biological cells 900.

[0045] The electromagnetic wave irradiation unit 102 irradiates electromagnetic waves (e.g., microwaves) onto the diamond-containing biological cells 900. The electromagnetic wave irradiation unit 102 is, for example, a coil formed by incorporating a conductor. The electromagnetic waves are supplied to the electromagnetic wave irradiation unit 102 from the electromagnetic wave generation unit 132 via, for example, a coaxial cable. The excitation light and electromagnetic wave irradiation of the diamond-containing biological cells 900 are controlled by the control unit 130, for example, in… Figure 3 It will be carried out at the timing shown.

[0046] Reference Figure 3 The control unit 130 controls the excitation light generating unit 110 to output excitation light for a predetermined time (e.g., period t1) at a predetermined time. The control unit 130 controls the electromagnetic wave generating unit 132 to output electromagnetic waves at a predetermined time (e.g., period t2) and at a predetermined time. An appropriate pulse sequence can be used for period t2. Thus, the electromagnetic waves and excitation light are combined in time and space to irradiate the diamond. As described later, the control unit 130 reads the output signal of the input light detection unit 120 at a predetermined time (e.g., within period t3) and stores it in the storage unit.

[0047] The NV center has a structure where carbon (C) atoms in a diamond crystal are replaced by nitrogen (N) atoms, and no adjacent carbon atoms are present (i.e., a void (V)). The NV center transitions from a base state to an excited state by emitting green light (e.g., a 532 nm laser) with wavelengths from 490 nm to 560 nm, and returns to the base state by emitting red light (e.g., a 637 nm fluorescence) with wavelengths from 630 nm to 800 nm. If the NV center forms a magnetic quantum number m in a state where it has trapped one electron (i.e., NV-),... s If m is a spin triplet state of -1, 0, or +1 and a magnetic field exists, then s The energy levels of the ±1 state are separated according to the magnetic field strength (i.e., Zeeman separation). Irradiating the NV center with a 2.87 GHz microwave will... s The state of =0 transitions to m s After reaching a state of ±1 (i.e., electron spin resonance), green light is excited by irradiation. As a result, since the transition back to the basement state includes a transition from non-emissive light (i.e., fluorescence), the intensity of the observed emitted light decreases. Therefore, a trough (i.e., a signal dip) is observed in the ESR (Electron Spin Resonance) spectrum. As described above, the control unit 130, by controlling the excitation light generation unit 110 and the electromagnetic wave generation unit 132, for example, measures... Figure 4 The spectrum is as shown. The observed Δf depends on the magnetic field strength at the location of the diamond within the biological cell 900. The control unit 130 can calculate the magnetic field based on Δf.

[0048] Fluorescence emitted from the diamond 100 of the biological cell 900 is directed into the second end of the optical waveguide 116, transmitted through the waveguide 116, and output to the first end, where it is directed into the focusing element 114. The focusing element 114 expands the fine fluorescence output from the optical waveguide 116 into parallel light and outputs it to the filter 112. The filter 112 allows the fluorescence, as described above, to pass through and be directed into the LPF 118.

[0049] LPF118 is a long-pass filter that allows light with wavelengths above a predetermined wavelength to pass through while blocking (e.g., reflecting) light with wavelengths shorter than the predetermined wavelength. Diamond emits red light, which passes through LPF118, but the excitation light output from excitation light generation unit 110 has a shorter wavelength and therefore does not pass through LPF118. Thus, the excitation light emitted from excitation light generation unit 110 is detected by photodetector unit 120 and becomes noise, suppressing the decrease in detection sensitivity of diamond's emitted light (i.e., fluorescence). Photodetector unit 120 generates and outputs an electrical signal corresponding to the incident light. Photodetector unit 120 is, for example, a photodiode. The output signal of photodetector unit 120 is acquired by control unit 130.

[0050] The nitrogen concentration in the diamond is selected to be above 0.5 ppm and below 300 ppm, depending on the required accuracy of the physical quantity being observed (magnetic field, electric field, or temperature, etc.). Since the fluorescence from the NV-center is reduced by radiation such as X-rays, the nitrogen content is preferably above 1 ppm.

[0051] In the above configuration, X-rays of 1 μGy / h or higher, for example, generated by applying an accelerating voltage of 10 kV or higher and an electron beam current of 10 mA or higher to a molybdenum or copper target, are used to irradiate biological cells 900 while fluorescence is observed. For example, body temperature changes in samples containing biological cells 900 can be observed from a distance of more than 1 Gy, allowing for in-situ observation of the effects of radiation on the organism.

[0052] In the above section, the calculation of the magnetic field based on the change of the ESR spectrum was explained. However, it is known that the resonant frequency of the NV center is temperature-dependent in the range of 120K to 700K. For example, as disclosed in Non-Patent Document 2, the temperature can be measured based on the frequency change of the ODMR (Optically Detected Magnetic Resonance) signal.

[0053] Figure 2 The excitation light generating unit 110, filter 112, focusing element 114 and optical waveguide 116 shown constitute the excitation light irradiation unit, and the optical waveguide 116, focusing element 114, filter 112, LPF 118 and light detection unit 120 constitute the fluorescence collecting unit. Figure 2 In the configuration shown, all elements except the biological cells 900 and the electromagnetic wave irradiation unit 102 are positioned where they are not irradiated by the radiation 902. Therefore, in an environment where radiation from X-rays or electron beams is interspersed, the elements used for measurement can be prevented from being affected by radiation, and the degradation of the optical waveguide 116 can be suppressed.

[0054] Because diamond, composed of the light element carbon, has a small reaction cross-section based on radiation, the NV sensor itself is less affected by radiation in measurements such as magnetic fields, making it difficult to hinder its operation. The radiation can be alpha lines, beta lines, or neutral lines, etc. A low radiation level (e.g., below 500 mgy) is sufficient, ensuring that the diamond's transmittance does not decrease. As described above, it is possible to measure magnetic fields, electric fields, and temperatures in environments with radiation levels exceeding 1 μGy / h, which were previously difficult to measure. Similarly, it is possible to measure magnetic fields, electric fields, and temperatures in harsh radiation environments exceeding 1 mGy / h, further exceeding 1 Gy / h, and further exceeding 1 kGy / h.

[0055] Furthermore, the coaxial cable used to transmit microwaves to the electromagnetic wave irradiation unit 102 is not a resin-coated coaxial cable, but preferably a coaxial cable covered by a component with high resistance to X-ray damage, such as alumina.

[0056] (Second Implementation) Diamond spin sensors can be mounted on devices that utilize radiation. (See reference...) Figure 5 The diamond spin sensor involved in the second embodiment of this disclosure is disposed in an X-ray diffraction (XRD) apparatus.

[0057] The X-ray diffraction apparatus includes an X-ray generating device 200, a goniometer 206, and a detector 208. The X-ray generating device 200 includes a high-voltage generating unit 202 and an X-ray tube 204. The high-voltage generating unit 202 generates high voltage and supplies it to the X-ray tube 204. The X-ray tube 204 accelerates electrons through the high voltage supplied from the high-voltage generating unit 202, irradiating an internal target to generate X-rays. The generated X-rays are irradiated onto a sample 904 disposed on the goniometer 206. The sample 904 is the object of measurement and is mounted on a sample holder (not shown). The diamond 134 of the diamond spin sensor is, for example, disposed within 10 mm of the sample holder (i.e., within 10 mm of the sample 904). The diamond 134 includes an NV center. The diamond 134 is not a powder like diamond 100, but a crystal of a predetermined size (e.g., a pyramid with a bevel length of 1 mm, described later as an example). If X-rays are irradiated onto the sample 904, the X-rays are emitted after diffraction in a predetermined direction based on the crystal structure of the sample 904. The sample 904 is rotated by the goniometer 206 and the diffracted X-rays are detected by the detector 208.

[0058] The X-ray tube 204, for example, contains a target of molybdenum or copper. An accelerating voltage of 10 kV or more and an electron beam current of 10 mA or more are applied to the target by the high voltage generating unit 202, thereby generating X-rays of 1 μGy / h or more.

[0059] Figure 5 Not shown in the image, but through... Figure 2 Using the same configuration, instead of biological cells 900, diamond 134 is irradiated with excitation light and microwaves, and the fluorescence emitted from diamond 134 is detected. This allows for the measurement of magnetic fields, electric fields, or temperatures generated at the location of diamond 134. For example, it allows for the measurement of the temporal change in the magnetic field of sample 904 during X-ray irradiation of sample 904.

[0060] In such Figure 5 When the diamond 134 is arranged within the X-ray diffraction apparatus, the elements used for measurement (i.e., the excitation light irradiation section, the fluorescence collection section, and the control section 130 for controlling the excitation light irradiation section and the fluorescence collection section, etc.) are positioned so as not to be irradiated by X-rays emitted from the X-ray tube 204 or by X-rays diffracted by the sample 904. This avoids the elements used for measurement from being affected by X-rays and suppresses the deterioration of the optical waveguide 116 that transmits excitation light and fluorescence.

[0061] (Third Implementation) Diamond spin sensors can also be mounted in devices that use charged particles (such as electron beams). (See reference...) Figure 6The diamond spin sensor involved in the third embodiment of this disclosure is disposed in an electron beam irradiation device (EPS: Electronbeam Processing System).

[0062] The electron beam irradiation device 220 has a shielding member 222 and a rectangular electron beam exit window (not shown), as... Figure 6 The electron beam is output as indicated by the downward arrow (negative direction of the Z-axis). The electron beam output from the electron beam irradiation device 220 irradiates the object 906, thereby enabling modification and quality improvement of the object 906. The electron beam irradiation device 220 is used, for example, to improve the heat resistance of cross-linked wire coverings, improve the quality of foamed polyethylene, reduce the weight and improve the quality of automotive tires, or modify packaging films. Furthermore, the electron beam irradiation device 220 can also be used for sterilization and disinfection of medical devices, or for improving the properties of semiconductors.

[0063] Diamond 134 is positioned within 100 mm of the end of the electron beam exit window of the electron beam irradiation device 220 (e.g., at four corners of a rectangle). Figure 6 Not shown in the image, but through... Figure 2 With the same configuration, each diamond 134 is irradiated with excitation light and microwaves, and the fluorescence emitted from each diamond 134 is detected. Excitation light transmitted through optical waveguide 116 is irradiated into each diamond 134. The fluorescence emitted from the diamond 134 is transmitted to the detection unit through optical waveguide 116.

[0064] If the object 906 is irradiated with an electron beam output from the electron beam irradiation device 220, then as Figure 6 As indicated by the dashed arrow, X-rays are emitted from the object 906 in random directions, and stray electrons are also generated. Therefore, the diamond 134 and the optical waveguide 116 are exposed to the X-rays emitted from the object 906 and the stray electrons. As a countermeasure, the diamond spin sensor according to the third embodiment, such as... Figure 7 It is constructed as shown. Figure 7 The XYZ axes shown are Figure 6 The XYZ axes are shown.

[0065] Reference Figure 7The diamond spin sensor includes a diamond 134, a focusing element 126, an optical waveguide 116 for transmitting excitation light and fluorescence, a coaxial cable 122 for transmitting microwaves and irradiating the diamond 134, an impedance transformer 125, a microwave resonator 124, and a shielding member 128 housing the above components. The impedance transformer 125 is, for example, a λ / 4 transformer, and the microwave resonator 124 is, for example, a λ / 4 short wire. The microwave resonator 124 and the impedance transformer 125 function as resonators, increasing the magnetic field of the microwaves transmitted through the coaxial cable 122 and irradiating the diamond 134. (Refer to...) Figure 8 The shielding member 128 is a shape formed by combining the first shielding part 140, the second shielding part 142, and the third shielding part 144. Figure 8 The XYZ axes shown are Figure 7 The XYZ axes are shown. The blocking member 128 can be formed as a single unit after the first blocking portion 140, the second blocking portion 142, and the third blocking portion 144 are each formed, or it can be formed as a single unit from the beginning. The first blocking portion 140 is a cylindrical shape (e.g., a cylindrical shape) with a thickness th and an inner wall surface 146. The space enclosed by the inner wall surface 146 accommodates... Figure 7 The diamond 134, focusing element 126, optical waveguide 116, coaxial cable 122, impedance transformer 125, and microwave resonator 124 are shown. The second shielding portion 142 and the third shielding portion 144 are, for example, shaped like a hemisphere of radius r divided into two equal parts, and are arranged with a gap φ between them along the Z-axis. An opening 138 of a size (e.g., expressed by the solid angle centered on the focusing element 126) is provided on the inner wall surface 146 so that the radiation does not directly contact the optical waveguide 116, etc., and the diamond 134 is placed near the opening 138 and exposed.

[0066] An electron beam emitted from the electron beam irradiation device 220 forms a magnetic field H around the electron's direction of travel (i.e., the Z-axis) (i.e., within the XY plane). The gap 148 extends within the XY plane, and the magnetic field formed in the gap 148 is unaffected by the second shielding portion 142 and the third shielding portion 144. As described above, the magnetic field formed in the gap 148 is measured by irradiating the diamond 134 with excitation light and microwaves and detecting the fluorescence emitted from the diamond 134. Electromagnetic waves are supplied from a microwave generator (not shown) through a coaxial cable 122, for example, with a ceramic insulator such as silica glass, at an intensity of 3 mW or more. The excitation light output from the excitation light generating unit 110 is irradiated onto the diamond 134 via a focusing element 126 through an optical waveguide 116 at an intensity of, for example, 1 mW or more, preferably 10 mW or more.

[0067] The shielding member 128 is formed of a component that blocks radiation (here, X-rays and stray electrons), suppressing the exposure of the diamond 134, optical waveguide 116, focusing element 126, coaxial cable 122, and microwave resonator 124, which are housed in the space enclosed by the inner wall surface 146, to radiation. The shielding member 128 is formed, for example, of lead (Pb) or stainless steel (SUS: Steel Special Use Stainless). For example, when the accelerating voltage of the electron beam irradiation device 220 is 100 keV and the electron beam current is 100 mA, the thickness th of the first shielding portion 140 is preferably 2 mm or more. When the accelerating voltage of the electron beam irradiation device 220 is 300 keV or more and 500 keV or more (electron beam current is 100 mA), the thickness th of the first shielding portion 140 is preferably 5 mm or more and 20 mm or more, respectively.

[0068] By configuring diamond spin sensors in this manner, it is possible to measure the magnetic field of the electron beam emitted from the electron beam exit window of the electron beam irradiation device 220 and calculate the current based on the electron beam based on the measured value. By configuring multiple diamond spin sensors (e.g., near the four corners of the electron beam exit window), it is possible to determine the distribution of the current based on the electron beam. By providing a shielding member 128 and accommodating the optical waveguide 116, diamond 134, coaxial cable 122, and focusing element 126 within the space enclosed by its inner wall 146, it is possible to prevent the optical waveguide 116 used for measurement from being affected by X-rays and stray electrons generated by the electron beam irradiation of the object 906, and to reliably suppress the degradation of the optical waveguide 116 and the like that transmitting excitation light and fluorescence.

[0069] As described above, the second shielding portion 142 and the third shielding portion 144 are arranged at a distance φ, and the opposing surfaces of the second shielding portion 142 and the third shielding portion 144 are perpendicular to the running direction of the electron beam. This suppresses the influence of the second shielding portion 142 and the third shielding portion 144 on the magnetic field H formed by the electron beam. Therefore, the magnetic field H formed by the electron beam can be accurately measured.

[0070] Furthermore, the first blocking portion 140 is not limited to a cylinder, and can also be a component with an inner wall surface 146 formed on a prism. Additionally, the second blocking portion 142 and the third blocking portion 144 are not limited to the shape of dividing a hemisphere into two equal parts, and can also be cuboids, etc. The second and third blocking portions can be arranged with a gap φ between them. For example, see reference... Figure 9 The component used to shield radiation can also be a component with an inner wall surface 162 formed in a prismatic shielding component 160 and a gap 164 with a spacing φ. Figure 9 The XYZ axes shown are Figure 8The XYZ axes are shown. The space enclosed by the inner wall surface 162 accommodates... Figure 7 The diamond 134, focusing element 126, optical waveguide 116, coaxial cable 122, and microwave resonator 124 are shown.

[0071] Alternatively, electromagnetic waves can be supplied from a microwave generator at an intensity of 50mW or higher via a coaxial cable insulated with ceramic materials such as silica glass. Various pulse sequences can be used for electromagnetic wave irradiation. For example, a free induction decay (FID) signal or a pulse sequence used to measure spin echo signals based on the Hahn echo method can be used as a magnetic resonance signal.

[0072] In addition, to read out the phase information of the electron spin state of diamond 134, pulsed excitation light can be generated from the excitation light generation unit 110 by means of an acousto-optic modulator (AOM) or electrical modulation. The pulsed excitation light is transmitted through the optical waveguide 116 and irradiated onto diamond 134, and the fluorescence is observed, thereby reading out the phase information of the electron spin state of diamond 134.

[0073] (Fourth Implementation) In situations requiring high-sensitivity measurement of magnetic fields, it is preferable to fully expose the diamond from the obstruction. The diamond spin sensor according to the fourth embodiment of this disclosure is configured similarly to the third embodiment, with the diamond positioned in a location exposed to radiation. The diamond spin sensor according to this embodiment can be mounted in an electron beam-using device (e.g., an electron beam irradiation device), just as in the third embodiment.

[0074] Reference Figure 10 The diamond spin sensor involved in this embodiment includes a diamond 134, an optical element 136, an optical waveguide 116 for transmitting excitation light and fluorescence, a coaxial cable 122 for transmitting microwaves and irradiating the diamond 134, a microwave resonator 124, and a shielding member 128 accommodating these components. The shielding member 128 is as follows... Figure 8 It forms as shown. The portion of range A1 is... Figure 8 The first shielding portion 140 shown corresponds to this. The optical waveguide 116, coaxial cable 122, and optical element 136 are housed in the space enclosed by the inner wall surface 146. Diamond 134 and microwave resonator 124 are disposed on the outer side of the inner wall surface 146.

[0075] Optical element 136 is, for example, a telescope lens. Optical element 136 is positioned at a distance L1 from diamond 134 and focuses the excitation light transmitted through optical waveguide 116 and output from its second end toward diamond 134. Thus, excitation light can be irradiated toward diamond 134, which is disposed outside the inner wall surface 146, while the optical waveguide 116 is surrounded by the inner wall surface 146.

[0076] In the shielding member 128, the portion of area A2, namely the wall surface (including a portion of the inner wall surface 146) that divides the space accommodating the diamond 134, the microwave resonator 124, and the optical element 136, is formed into a mirror shape by metal vapor deposition or polishing. The fluorescence emitted from the diamond 134 is reflected and focused by the mirror-shaped wall surface, and then enters the optical waveguide 116 via the optical element 136.

[0077] When a diamond spin sensor configured in this way is placed in an electron beam irradiation device 220, the current and its distribution based on the electron beam emitted from the electron beam exit window of the electron beam irradiation device 220 can be measured. By providing a shielding member 128 and accommodating the optical waveguide 116 and coaxial cable 122 in the space enclosed by the inner wall surface 146, the optical waveguide 116 used for measurement can be prevented from being exposed to X-rays and stray electrons and being affected. Therefore, the degradation of the optical waveguide 116 and the like that transmitting excitation light and fluorescence can be reliably suppressed. In addition, by providing an optical element 136, the diamond 134 can be disposed outside the inner wall surface 146, thereby enabling high-sensitivity measurement of magnetic fields, electric fields, and temperature. By forming the wall portion (refer to region A2) that divides the space accommodating the diamond 134, microwave resonator 124, and optical element 136 into a mirror shape, the fluorescence emitted from the diamond 134 can be efficiently input into the optical waveguide 116.

[0078] (Fifth Implementation) Under high-intensity radiation, it is preferable to position the optical waveguide (i.e., optical fiber), which is easily degraded by radiation, further inward than the shielding member. The diamond spin sensor according to the fifth embodiment of this disclosure is constructed similarly to the third embodiment, with the optical waveguide positioned further inward than the radiation shielding member. The diamond spin sensor according to this embodiment can be mounted in an electron beam-using device (e.g., an electron beam irradiation device), just as in the third embodiment.

[0079] Reference Figure 11 The diamond spin sensor involved in this embodiment includes a diamond 134, a shielding member 128, a fourth shielding part 150, and a reflective member 152. The shielding member 128 is as follows... Figure 8As shown, the fourth shielding portion 150 is formed in the same cylindrical shape (e.g., a cylindrical shape) as the first shielding portion 140, and a space for accommodating the optical waveguide 116 is formed through its inner wall surface. Figure 11 In the middle, the head is 170 and Figure 7 The same configuration is used (except for the optical waveguide 116 and the focusing element 126). Figure 11 In the diagram, the coaxial cable 122 and the microwave resonator 124 are not shown.

[0080] The fourth shielding portion 150, like the shielding member 128, is formed of a member that blocks radiation. The optical waveguide 116 is configured to be housed within a space defined by the inner wall of the fourth shielding portion 150, with its second end (i.e., the end from which the excitation light is emitted) located near the reflecting member 152. The reflecting member 152 is a concave mirror (e.g., the shape of the mirror surface is part of a parabola). The reflecting member 152 is positioned at the junction 172 of the shielding member 128 and the fourth shielding portion 150, separated from the diamond 134 by a distance L2. The excitation light transmitted through the optical waveguide 116 and emitted from its second end is reflected by the mirror surface of the reflecting member 152 and focused towards the diamond 134. The reflecting member 152 may also be a plane mirror.

[0081] Microwaves irradiated onto diamond 134 are transmitted via a coaxial cable (not shown) to a microwave resonator (not shown) located near diamond 134. The coaxial cable can be configured similarly to the optical waveguide 116, connecting to the microwave resonator through a space divided by the inner wall of the fourth shielding portion 150, and through a space enclosed by the inner wall 146 by the bend at the joint 172.

[0082] The inner wall surface 146 is preferably formed into a mirror shape in region A3 by metal vapor deposition or polishing. Fluorescence emitted from the diamond 134 is reflected and focused by the mirror-shaped inner wall surface 146, then incident on the mirror surface of the reflecting member 152 and reflected by the mirror before entering the optical waveguide 116. The fluorescence is transmitted through the optical waveguide 116 and detected by a detector (e.g., Figure 2 The light detection unit 120 is used for detection.

[0083] When a diamond spin sensor configured in this way is placed in an electron beam irradiation device 220, the current and its distribution based on the electron beam emitted from the electron beam exit window of the electron beam irradiation device 220 can be measured. By providing a fourth shielding portion 150 and accommodating the optical waveguide 116 within its internal space, and by providing a reflective member 152, the optical waveguide 116 used for measurement can be prevented from being affected by X-rays and stray electrons, and the degradation of the optical waveguide 116 and the optical waveguide that transmits excitation light and fluorescence can be suppressed more reliably. By forming the wall portion (refer to region A3) that divides the space accommodating the diamond 134 and the reflective member 152 into a mirror shape, the fluorescence emitted from the diamond 134 can be efficiently input into the optical fiber.

[0084] In the above section, the case of using diamond with an NV center for diamond 134 was described, but it is not limited to this. Any diamond with a color center carrying electron spin is acceptable. A color center with electron spin is a center that forms a spin triplet state and emits light upon excitation; the NV center is a representative example. Furthermore, color centers with electron spin are also known to exist in silicon-void centers (i.e., Si-V centers), germanium-void centers (i.e., Ge-V centers), and tin-void centers (i.e., Sn-V centers). Therefore, diamonds containing any of these can also be used as diamond 134 to construct a diamond spin sensor.

[0085] Example 1 The effectiveness of this disclosure is illustrated below through examples. The manufacture and use of... Figure 2 as well as Figure 7 An experiment was conducted using a diamond spin sensor assembled from these components and placed in an electron beam irradiation device.

[0086] Diamonds are classified according to the presence and type of impurities. For the fabrication of diamond 134, type Ib containing nitrogen atoms as impurities (i.e., having NV centers) was used. The electron beam acceleration energy was 3 MeV, and the electron beam dose was 3 × 10⁻⁶. 18 pcs / cm 2 Electrons were injected into the diamond, which was then annealed at 900°C for 1 hour to produce a diamond containing an NV center. This diamond was then cut into a pyramidal shape with a bevel length of 1 mm to produce diamond 134.

[0087] The head of the diamond with a diamond spin sensor is as follows Figure 7The configuration is shown. The thickness th of the shielding member 128 is set to 4 mm. A 5 mW green light is used as the excitation light to irradiate the diamond 134 fabricated as described above. A microwave irradiation of the diamond 134 is performed by scanning a 3 dBm frequency signal from a VCO (Voltage-controlled oscillator) between 2.74 GHz and 2.94 GHz. During the scan, fluorescence intensity is measured, and magnetic resonance is observed well even under radiation conditions. Thus, the electron beam current emitted from the electron beam irradiation device with an accelerating voltage of 3 MeV is measured to be 11 mA.

[0088] The present disclosure has been described above by way of example, and the present disclosure is not limited to the above-described embodiments. The scope of the present disclosure is defined by the claims, based on the detailed description of the invention, and includes all modifications that have the same meaning and scope as the statements therein.

[0089] Explanation of reference numerals in the attached figures 100, 134: Diamond; 102: Electromagnetic wave irradiation section; 104: Optical devices; 106: Excitation light; 108: Fluorescence; 110: Excitation light-generating part; 112: Filter; 114, 26: Concentrating element; 116: Optical waveguide; 118: LPF; 120: Optical Detection Department; 122: Coaxial cable; 124: Microwave resonator; 125: Impedance transformer; 128, 160, 222: Barrier components; 130: Control Department; 132: Electromagnetic wave generating unit; 136: Optical components; 138: Opening; 140: First shielding part; 142: Second shielding part; 144: Third shielding part; 146, 162: Inner wall surface; 148, 164: gaps; 150: Fourth shielding part; 152: Reflective component; 170: Head; 172: Joint; 200: X-ray generating device; 202: High-voltage generation unit; 204: X-ray tube; 206: Goniometer; 208: Detector; 220: Electron beam irradiation device; 900: Somatic cells of organisms; 902: Radiation; 904: Sample; 906: Object; A1, A2, A3: Scope; L1, L2: Distance; r: radius; th: thickness; φ: Interval.

Claims

1. A diamond spin sensor, wherein, The diamond spin sensor includes: Diamond has color centers with electron spin; and An optical waveguide transmits excitation light irradiating the diamond and fluorescence emitted from the diamond. When the diamond is placed in an environment with radiation of 1 μGy / h or higher, the magnetic field, electric field, or temperature in the environment is measured by the color center.

2. The diamond spin sensor according to claim 1, wherein, The diamond spin sensor also includes: An excitation light irradiation section is used to irradiate the diamond with excitation light; and A fluorescence collecting section collects the fluorescence emitted from the diamond. The optical waveguide, the excitation light irradiation unit, and the fluorescence collection unit are positioned in a location that is not exposed to the radiation.

3. The diamond spin sensor according to claim 2, wherein, The optical waveguide is an optical fiber. The diamond spin sensor also includes a metal component that blocks radiation with energies above a predetermined value. The metal component covers or is disposed around the optical fiber in such a manner that at least the optical fiber is not exposed to radiation exceeding 1 μGy / h. The radiation includes X-rays or electron beams.

4. The diamond spin sensor according to claim 3, wherein, The diamond is exposed from the metal component.

5. The diamond spin sensor according to claim 3 or 4, wherein, The metal component includes a cylindrical first shielding portion. The optical fiber has an output end that outputs the excitation light. The optical fiber is configured to pass through the first shielding portion and to house the output end within the first shielding portion.

6. The diamond spin sensor according to claim 5, wherein, The metal component further includes a second shielding portion and a third shielding portion. The second and third blocking portions are spaced apart from each other by a predetermined interval and are combined with the end of the first blocking portion.

7. The diamond spin sensor according to claim 6, wherein, The diamond spin sensor also includes optical elements housed in the first shielding portion. The diamond is disposed in the second and third blocking portions at the end opposite to the portion that engages with the end of the first blocking portion. The optical element irradiates the diamond with the excitation light output from the optical fiber.

8. The diamond spin sensor according to claim 7, wherein, In the first shielding portion, the second shielding portion, and the third shielding portion, the wall portion forming the space for accommodating the diamond and the optical element is formed as a mirror.

9. The diamond spin sensor according to any one of claims 5 to 8, wherein, The diamond spin sensor further includes a reflective component housed in the first shielding portion. The diamond is separated from the reflective member and housed in the first shielding portion. The reflective component reflects the excitation light output from the optical fiber and irradiates the diamond.

10. The diamond spin sensor according to claim 9, wherein, In the first shielding portion, the wall portion forming the space for accommodating the diamond and the reflective member is formed as a mirror.

11. The diamond spin sensor according to any one of claims 1 to 10, wherein, The nitrogen content in the diamond is above 0.5 ppm and below 300 ppm.

12. The diamond spin sensor according to any one of claims 1 to 11, wherein, The power density of the excitation light irradiating the diamond is 10 mW / mm². 2 above.

13. An apparatus comprising a diamond spin sensor according to any one of claims 2 to 10, wherein, The excitation light irradiation unit and the fluorescence collection unit are disposed outside the X-ray or electron beam generating device or generating area.

14. The apparatus according to claim 13, wherein, The nitrogen content in the diamond is above 0.5 ppm and below 300 ppm.

15. The apparatus according to claim 13 or 14, wherein, The power density of the excitation light irradiating the diamond is 10 mW / mm². 2 above.

16. An apparatus in which, The device comprises the diamond spin sensor according to any one of claims 1 to 12. The device uses X-rays or electron beams.

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