Measuring device, measuring method, and program

Abstract

To provide a measuring device, a measuring method, and a program capable of precisely measuring an SEU cross section originating from particles.SOLUTION: A measuring device includes: an accelerator 11 for emitting protons; a deceleration board for decelerating the protons emitted from the accelerator 11; a first calculation section 22 for calculating the number of neutrons occurring in the deceleration board on the basis of proton energy emitted from the accelerator 11 and a thickness of the deceleration board; a second calculation section 23 for calculating an SEU cross section originating from neutrons occurring in a device 3 on the basis of the proton energy; a third calculation section 24 for calculating SEU originating from the neutrons occurring in the device 3 on the basis of the number of the neutrons and an SEU cross section originating from the neutrons; and a fourth calculation section 26 for calculating an SEU cross section originating from protons on the basis of SEU occurring in the device 3 and SEU originating from the neutrons.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a measurement apparatus, a measurement method, and a program for measuring an SEU (Single Event Upset) cross section. [Background Art]

[0002] When a single particle (such as neutron, proton, heavy ion) collides with a device such as an LSI or a memory, SEU, which is a phenomenon that causes bit inversion, occurs. A value obtained by dividing the number of SEUs occurring when particles are irradiated by the irradiated fluence (the total number of particles that pass through per unit area) is referred to as the SEU cross section. That is, the SEU cross section can be calculated by "(number of SEU occurrences) / (irradiated particle fluence)".

[0003] When measuring the SEU cross section of energy-dependent particles (e.g., protons), it is necessary to change the energy of the particles to measure the number of SEU occurrences.

[0004] As a method for changing the energy of particles, Non-Patent Document 1 discloses a method of changing the velocity of particles with an accelerator to change the energy of particles irradiated to a device. Non-Patent Document 2 discloses a method of attenuating particle energy by causing particles having a specific energy generated by an accelerator to collide with a deceleration plate. [Prior Art Documents] [Non-Patent Documents]

[0005] [Non-Patent Document 1] https: / / ieeexplore.ieee.org / document / 4077290 [Non-Patent Document 2] https: / / ieeexplore.ieee.org / document / 7482480 [Summary of Invention] [Problem to be Solved by Invention]

[0006] However, the method of changing the velocity of particles irradiated from an accelerator, as described in Non-Patent Document 1, has the problem that it is difficult to flexibly change the energy of the particles, and that setting up and adjusting the accelerator takes a long time.

[0007] On the other hand, the method using a speed reducer described in Non-Patent Document 2 has the problem that neutrons are generated when particles (for example, protons) collide with the speed reducer, and SEUs originating from these neutrons are generated, making it difficult to measure particle-derived SEU crosssections with high precision.

[0008] This disclosure is made in view of the above circumstances and aims to provide a measuring device, a measuring method, and a program capable of measuring particle-derived SEU crosssections with high precision. [Means for solving the problem]

[0009] A measuring device in one aspect of the present disclosure is a measuring device for measuring SEU cross-sections, comprising: an accelerator for irradiating a device with particles; a deceleration plate installed between the accelerator and the device for slowing down particles irradiated from the accelerator; a first calculation unit for calculating the number of neutrons generated at the deceleration plate based on the particle energy irradiated from the accelerator and the thickness of the deceleration plate; a second calculation unit for calculating the neutron-derived SEU cross-section generated at the device based on the particle energy; a third calculation unit for calculating the neutron-derived SEU generated at the device based on the number of neutrons and the neutron-derived SEU cross-section; and a fourth calculation unit for calculating the particle-derived SEU cross-section based on the SEU generated at the device and the neutron-derived SEU.

[0010] A measurement method in one aspect of the present disclosure is a measurement method for measuring SEU cross-sections, comprising: irradiating a device with particles irradiated from an accelerator and decelerated by a decelerator; calculating the number of neutrons generated at the decelerator based on the particle energy of the particles irradiated from the accelerator and the thickness of the decelerator; calculating the neutron-derived SEU cross-section generated at the device based on the particle energy; calculating the neutron-derived SEU generated at the device based on the number of neutrons and the neutron-derived SEU cross-section; and calculating the particle-derived SEU cross-section based on the SEU generated at the device and the neutron-derived SEU.

[0011] One aspect of this disclosure is a program for causing a computer to function as the above-mentioned measuring device. [Effects of the Invention]

[0012] According to this disclosure, it will be possible to measure particle-derived SEU crosssections with high precision. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a block diagram showing the configuration of the measuring device and peripheral equipment according to this embodiment. [Figure 2] Figure 2 is an explanatory diagram showing the configuration of the measuring device and peripheral equipment according to the embodiment. [Figure 3] Figure 3 is a graph showing the proton spectra when the thickness of the deceleration plate is varied. [Figure 4] Figure 4 is a graph showing the correspondence data between neutron energy and neutron flux (first correspondence data). [Figure 5] Figure 5 is a graph showing the correspondence data (second correspondence data) between neutron energy and neutron-derived SEU cross-sections. [Figure 6] Figure 6 is a flowchart showing the processing procedure of the measuring device according to the embodiment. [Figure 7]Fig. 7 is a block diagram showing the hardware configuration of the present embodiment. MODES FOR CARRYING OUT THE INVENTION

[0014] Hereinafter, a measuring apparatus according to an embodiment will be described with reference to the drawings. Fig. 1 is a block diagram showing a detailed configuration of a measuring apparatus 100 according to the embodiment, and Fig. 2 is an explanatory diagram showing configurations of the measuring apparatus 100 and a device 3 to be observed. As shown in Fig. 1 and Fig. 2, the measuring apparatus 100 includes an irradiation apparatus 1 and an arithmetic apparatus 2. The measuring apparatus 100 irradiates the device 3 with particles (e.g., protons) and measures a particle-derived SEU cross-section in the device 3.

[0015] The irradiation apparatus 1 includes an accelerator 11 and a switching mechanism 12.

[0016] The accelerator 11 irradiates accelerated particles obtained by accelerating particles onto a deceleration plate D (D1 to Dn) provided in the switching mechanism 12. In the present embodiment, an example in which protons are used as particles irradiated from the accelerator 11 will be described. The accelerator 11 accelerates, for example, protons such that the energy of the protons becomes 20 [MeV].

[0017] The switching mechanism 12 includes a plurality of deceleration plates D (D1 to Dn) having different thicknesses. The switching mechanism 12 selects one deceleration plate D from the plurality of deceleration plates having different thicknesses. The deceleration plate D is disposed between the accelerator 11 and the device 3, and decelerates protons (particles) irradiated from the accelerator 11. The switching mechanism 12 can select the deceleration plate D to be used by a user's operation. Hereinafter, the thickness of the deceleration plate D1 is denoted as t1, and the thickness of the deceleration plate D2 is denoted as t2. Accordingly, the thickness of the deceleration plate Dn is tn. For example, an aluminum plate may be used as the deceleration plate D.

[0018] The user can select any one of the deceleration plates D1 to Dn. FIG. 3 is a graph showing proton spectra when the thickness t of the deceleration plate D is varied. In FIG. 3, curve s1 shows data when an aluminum plate with a thickness of 1.0 [mm] is used, curve s2 shows data when an aluminum plate with a thickness of 1.5 [mm] is used, curve s3 shows data when an aluminum plate with a thickness of 1.8 [mm] is used, and curve s4 shows data when an aluminum plate with a thickness of 2.0 [mm] is used. It can be understood from the graph of FIG. 3 that proton energy can be changed by varying the thickness t of the deceleration plate D. That is, by operating the switching mechanism 12 to change the deceleration plate D, the energy of protons irradiated to the device 3 can be changed.

[0019] By irradiating accelerated protons (particles) from the accelerator 11 toward the deceleration plate D, the protons are decelerated in the deceleration plate D. When the decelerated protons irradiate the device 3, SEU occurs in the device 3. By measuring SEU, the proton-derived SEU cross-section in the device 3 can be calculated.

[0020] The arithmetic device 2 includes a measurement unit 21, a first calculation unit 22, a second calculation unit 23, a third calculation unit 24, a counting unit 25, and a fourth calculation unit 26.

[0021] The measurement unit 21 counts the number of protons accelerated by the accelerator 11. The count value of the number of protons is a numerical value corresponding to the energy of protons irradiated from the accelerator 11. The measurement unit 21 outputs the counted number of protons to the first calculation unit 22 and the second calculation unit 23.

[0022] The first calculation unit 22 acquires information on the number of protons counted by the measurement unit 21 and the thickness t of the deceleration plate D set by the switching mechanism 12. The first calculation unit 22 includes first correspondence data indicating the relationship between neutron energy and neutron flux (number of neutrons) for each of the thicknesses t1 to tn of the deceleration plates D1 to Dn.

[0023] Figure 4 is a graph showing the relationship between neutron energy and neutron flux when using aluminum plates with thicknesses of 1.0 mm, 1.5 mm, 1.8 mm, and 2.0 mm as deceleration plates D. The graph shown in Figure 4 is an example of the first corresponding data showing the relationship between neutron energy and neutron number. The graph shown in Figure 4 can be obtained by pre-simulation. Alternatively, data actually measured using multiple deceleration plates D may be used instead of simulation data.

[0024] The first calculation unit 22 obtains information on the thickness t of the deceleration plate D from the switching mechanism 12, and further calculates the neutron energy based on the number of protons obtained from the measurement unit 21. That is, since the number of protons accelerated in the accelerator 11 and the neutron energy correspond uniquely, the neutron energy can be calculated from the number of protons.

[0025] The first calculation unit 22 calculates the neutron flux (number of neutrons) based on the thickness t of the deceleration plate D and the neutron energy. Furthermore, it calculates the neutron fluence by multiplying the neutron flux by the irradiation time. The first calculation unit 22 outputs the calculated neutron fluence data (let's call this φ(E)) to the third calculation unit 24. The first calculation unit 22 calculates the number of neutrons generated at the deceleration plate D based on the proton energy (particle energy) irradiated from the accelerator 11 and the thickness t of the deceleration plate D.

[0026] Specifically, the first calculation unit 22 is equipped with first correspondence data showing the relationship between neutron energy and the number of neutrons, calculates neutron energy from particle energy, and calculates the number of neutrons by referring to the first correspondence data.

[0027] The second calculation unit 23 includes a graph (second corresponding data) showing the relationship between the neutron energy corresponding to the device 3 and the neutron-derived SEU crosssection, as shown in Figure 5, for example. The graph shown in Figure 5 is an example of the second corresponding data showing the relationship between the neutron energy and the neutron-derived SEU crosssection. The graph shown in Figure 5 can be obtained in advance through simulation. Alternatively, data actually measured using multiple deceleration plates D may be used instead of simulation results.

[0028] The second calculation unit 23 calculates the neutron-derived SEU cross-section based on the neutron energy obtained from the number of protons counted by the measurement unit 21, by referring to the graph shown in Figure 5. That is, the second calculation unit 23 calculates the neutron energy based on the proton energy (particle energy), and then calculates the neutron-derived SEU cross-section generated in device 3 by referring to the second corresponding data based on the calculated neutron energy.

[0029] The second calculation unit 23 outputs the calculated neutron-derived SEU cross-section data (referred to as σ(E)) to the third calculation unit 24.

[0030] The third calculation unit 24 calculates the number of neutron-derived SEUs N1 generated in device 3 based on the neutron fluence φ(E) and the neutron-derived SEU cross-section σ(E) described above. That is, the third calculation unit 24 calculates the number of neutron-derived SEUs generated in device 3 based on the number of neutrons (flux) calculated by the first calculation unit 22 and the neutron-derived SEU cross-section.

[0031] Specifically, the third calculation unit 24 calculates the number of neutron-derived SEUs N1 using the following equation (1).

[0032]

number

[0033] In equation (1), "E" represents energy. The third calculation unit 24 outputs the number of SEUs N1 originating from neutrons to the fourth calculation unit 26.

[0034] The counting unit 25 counts the number of SEUs N2 generated in device 3. The counting unit 25 outputs the counted number of SEUs N2 to the fourth calculation unit 26. The number of SEUs N2 includes proton-derived SEUs generated when device 3 is irradiated with protons, and neutron-derived SEUs generated when device 3 is irradiated with neutrons.

[0035] The fourth calculation unit 26 obtains the number of SEUs generated N2 output from the counting unit 25 and the number of neutron-derived SEUs generated N1 output from the third calculation unit 24. The fourth calculation unit 26 subtracts N1 from N2. This subtracted value (N2-N1) is the number of proton-derived SEUs, and is the value obtained by subtracting the number of neutron-derived SEUs generated at the deceleration plate D N1 from the number of SEUs generated N2.

[0036] The fourth calculation unit 26 calculates the proton-derived SEU cross-section by dividing the calculated number of proton-derived SEUs by the number of protons irradiated to device 3. In other words, the fourth calculation unit 26 calculates the proton (particle)-derived SEU cross-section based on the SEU count value and the neutron-derived SEUs.

[0037] Next, the procedure for irradiating device 3 with protons using the measurement device 100 described above and measuring the proton-derived SEU crosssection will be explained with reference to the flowchart shown in Figure 6. In this embodiment, an example of irradiation with protons is described as an example of particles, but it is also possible to use other particles.

[0038] First, in step S11, the user operates the switching mechanism 12 to select a speed reducer D of any thickness t from a plurality of speed reducer plates D1 to Dn.

[0039] In step S12, the user operates the accelerator 11 to irradiate, for example, a 20 [Mev] accelerated proton towards the deceleration plate D. As shown in Figure 2, the proton is decelerated when it is irradiated onto the deceleration plate D, and neutrons are generated at the deceleration plate D. The decelerated proton and the neutrons generated at the deceleration plate D are irradiated onto device 3. In device 3, SEU is generated by the irradiation of the decelerated proton and neutron.

[0040] In step S13, the counting unit 25 counts the SEUs generated in device 3 and outputs the count value N2 to the fourth calculation unit 26. As mentioned above, the count value N2 is the sum of the number of SEUs generated from protons and the number of SEUs generated from neutrons N1.

[0041] In step S14, the first calculation unit 22 obtains data on the thickness t of the deceleration plate D currently set from the switching mechanism 12, and also obtains the number of protons counted by the measurement unit 21. Based on the obtained number of protons, the first calculation unit 22 calculates the neutron energy irradiated onto the deceleration plate D. Based on the thickness t of the deceleration plate D and the neutron energy, the first calculation unit 22 calculates the neutron fluence by referring to the graph (first corresponding data) shown in Figure 4. The neutron fluence can be calculated based on the neutron flux (number of neutrons).

[0042] In step S15, the second calculation unit 23 calculates the neutron-derived SEU cross-section based on the neutron energy obtained from the number of protons counted by the measurement unit 21, by referring to the graph (second corresponding data) shown in Figure 5.

[0043] In step S16, the third calculation unit 24 calculates the number of neutron-derived SEUs N1 using equation (1) above, based on the neutron flux calculated by the first calculation unit 22 and the neutron-derived SEU cross-section calculated by the second calculation unit 23.

[0044] In step S17, the fourth calculation unit 26 subtracts the number of neutron-derived SEUs N1 from the number of SEUs N2 in device 3 to calculate the number of proton-derived SEUs (N2-N1).

[0045] In step S18, the fourth calculation unit 26 calculates the proton-derived SEU cross-section based on the number of SEUs generated by protons (N2-N1). In this way, the influence of SEUs generated by neutron irradiation of device 3 can be excluded, and the proton-derived SEU cross-section can be calculated.

[0046] As described above, the measuring device 100 according to this embodiment is a measuring device 100 for measuring SEU cross-sections, and comprises an accelerator 11 that irradiates a device 3 with particles (for example, protons), a deceleration plate D installed between the accelerator 11 and the device 3 to decelerate the particles irradiated from the accelerator 11, a first calculation unit 22 that calculates the number of neutrons generated at the deceleration plate D based on the particle energy irradiated from the accelerator 11 and the thickness t of the deceleration plate D, a second calculation unit 23 that calculates the neutron-derived SEU cross-section generated at the device 3 based on the particle energy, a third calculation unit 24 that calculates the neutron-derived SEU generated at the device 3 based on the number of neutrons and the neutron-derived SEU cross-section, and a fourth calculation unit 26 that calculates the particle-derived SEU cross-section based on the SEU generated at the device 3 and the neutron-derived SEU.

[0047] In this embodiment, the proton energy irradiated to the device 3 can be changed by a simple operation of changing the thickness t of the deceleration plate D, without changing the proton energy irradiated from the accelerator 11. Therefore, the operation of changing the proton energy irradiated from the accelerator 11 is unnecessary, reducing the effort required from the user.

[0048] Furthermore, it is possible to calculate the proton-derived SEU crosssection by excluding the influence of neutron-derived SEUs generated at the deceleration plate D. Therefore, it becomes possible to measure the proton-derived SEU crosssection with high accuracy.

[0049] In this embodiment, a switching mechanism 12 is provided to select one deceleration plate D from a plurality of deceleration plates D (D1 to Dn) with different thicknesses, making it possible to easily select a deceleration plate D with a desired thickness t and measure the proton-derived SEU cross-section.

[0050] In this embodiment, the first calculation unit 22 is equipped with a graph (first corresponding data) showing the relationship between neutron energy and neutron number (neutron flux), as shown in Figure 4. Since the neutron number is calculated based on the neutron energy by referring to the first corresponding data, it becomes possible to calculate the neutron number with simple operations without increasing the computational load.

[0051] In this embodiment, the second calculation unit 23 is equipped with a graph (second corresponding data) showing the relationship between neutron energy and neutron-derived SEU cross-section, as shown in Figure 5. Since the neutron-derived SEU cross-section is calculated based on the neutron energy and by referring to the second corresponding data, it becomes possible to calculate the neutron-derived SEU cross-section with simple operations without increasing the computational load.

[0052] In the embodiments described above, protons were used as an example of particles to irradiate device 3, but this disclosure is not limited to protons, and particles other than protons may be used.

[0053] As shown in Figure 7, the arithmetic unit 2 of the measuring device 100 of the above embodiment can be a general-purpose computer system comprising, for example, a CPU (Central Processing Unit, processor) 901, memory 902, storage 903 (HDD: Hard Disk Drive, SSD: Solid State Drive), communication device 904, input device 905, and output device 906. The memory 902 and storage 903 are storage devices. In this computer system, each function of the arithmetic unit 2 is realized when the CPU 901 executes a predetermined program loaded onto the memory 902.

[0054] The arithmetic unit 2 may be implemented on a single computer or on multiple computers. Furthermore, the arithmetic unit 2 may be a virtual machine implemented on a computer.

[0055] The program for the arithmetic unit 2 can be stored on computer-readable storage media such as HDDs, SSDs, USB (Universal Serial Bus) memory, CDs (Compact Discs), and DVDs (Digital Versatile Discs), or it can be distributed via a network. Computer-readable storage media are, for example, non-transitory storage media.

[0056] This disclosure is not limited to the embodiments described above, and numerous modifications are possible within the scope of its essence. [Explanation of Symbols]

[0057] 1 Irradiation device 2 Arithmetic unit 3 devices 11 Accelerator 12. Switching mechanism 21 Measuring part 22 First Calculation Unit 23 Second Calculation Unit 24 Third Calculation Department 25 Count Section 26. 4th Calculation Section 100 measuring devices D(D1~Dn) Deceleration plate

Claims

1. A measuring device for measuring SEU crosssections, An accelerator that irradiates the device with particles, A deceleration plate is installed between the accelerator and the device to slow down particles irradiated from the accelerator, A first calculation unit calculates the number of neutrons generated at the deceleration plate based on the particle energy irradiated from the accelerator and the thickness of the deceleration plate, A second calculation unit calculates a neutron-derived SEU crosssection generated in the device based on the particle energy, A third calculation unit calculates the neutron-derived SEU generated in the device based on the number of neutrons and the neutron-derived SEU crosssection, A fourth calculation unit calculates a particle-derived SEU cross-section based on the SEU generated in the aforementioned device and the neutron-derived SEU, A measuring device equipped with this device.

2. The device further comprises a counting unit for counting the SEU generated by the aforementioned device. The measuring device according to claim 1.

3. It further includes a switching mechanism that selects one speed reducer from multiple speed reducers of different thicknesses, The first calculation unit calculates the number of neutrons generated by the speed reducer based on the thickness of the speed reducer selected by the switching mechanism. The measuring device according to claim 1 or 2.

4. The first calculation unit includes first correspondence data showing the relationship between neutron energy and the number of neutrons. It calculates the neutron energy from the particle energy and calculates the number of neutrons by referring to the first correspondence data. The measuring device according to claim 1 or 2.

5. The second calculation unit is, The system includes a second correspondence data showing the relationship between neutron energy and the SEU crosssection originating from the neutron. The system calculates the neutron energy from the particle energy and, based on the neutron energy, calculates the SEU crosssection originating from the neutron by referring to the second correspondence data. The measuring device according to claim 1 or 2.

6. A measurement method for measuring SEU crosssections, Particles irradiated from the accelerator and slowed down by a deceleration plate are irradiated onto the device. Based on the particle energy of the particles irradiated from the accelerator and the thickness of the deceleration plate, the number of neutrons generated at the deceleration plate is calculated. Based on the aforementioned particle energy, the neutron-derived SEU crosssection generated in the device is calculated. Based on the number of neutrons and the neutron-derived SEU crosssection, the neutron-derived SEU generated in the device is calculated. Based on the SEU generated by the device and the neutron-derived SEU, the particle-derived SEU cross-section is calculated. Measurement method.

7. A program that causes a computer to function as the first calculation unit, second calculation unit, third calculation unit, and fourth calculation unit of the measuring device according to claim 1 or 2.

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