Neutron gamma detector with high dynamic range and time resolution

Abstract

The invention discloses a neutron gamma detector with a high dynamic range and time resolution. The neutron gamma detector comprises a plurality of layers of detection units, a plurality of neutron moderation bodies and a detector shell, each detection unit is arranged along the axis of the detector shell, a neutron moderator is arranged between every two detection units, each detection unit comprises a neutron / gamma sensitive scintillator array, a photomultiplier array and a pre-amplifier array, and each layer of neutron / gamma sensitive scintillator array is matched with one layer of photomultiplier array and one layer of pre-amplifier array. According to the detector, multiple layers of neutron slowing-down bodies are utilized to form gradients of neutron and gamma ray detection efficiency of each layer of scintillators, and a pulse counting matrix can be measured and obtained after the neutron / gamma sensitive scintillator array is matched with the photomultiplier tube array and the pre-amplifier array. And then neutron and gamma counting rates at each layer of detector are extracted. Meanwhile, based on the structural design of the detector, the time resolution and the dynamic range are improved.

Description

Technical Field

[0001] The present application belongs to the field of radiation measurement technology, and in particular relates to a neutron gamma detector with high dynamic range and time resolution. Background Art

[0002] The fusion neutron field generated by nuclear fusion plasma is filled with a large number of gamma rays and X-rays. Fusion neutrons carry information about the fuel ions in the plasma, gamma rays carry information about the various fast ions in the plasma, and X-rays carry information about the electrons in the plasma. To obtain relevant parameters of the fuel ions, neutron detectors are typically used to measure fusion neutrons; to obtain relevant parameters of the various fast ions and electrons, gamma / X-ray detectors are typically used to measure gamma and X-rays.

[0003] Fast physical processes in plasmas can occur on submillisecond timescales. To diagnose these fast processes, we need to improve the temporal resolution to submillisecond levels. Achieving high temporal resolution requires a high detector count rate (low count rates result in large statistical errors), so a detector with high detection efficiency is crucial. However, at sufficiently high count rates (e.g., count rates ≥ 1 Mcps), detector pulse signals can become significantly additive, even leading to signal saturation, making it impossible to further increase the count rate. Unfortunately, detector signal saturation is a common occurrence in fusion neutron measurements. This can be addressed by increasing the detector's dynamic range. Therefore, we need to not only improve the detector's temporal resolution but also expand its dynamic range.

[0004] Traditional neutron gamma detectors have their limitations: first, the detector pulse width limits its maximum counting rate. Even if the counting rate can exceed 1 Mcps, its pulse signals will overlap a lot, resulting in inaccurate measurements. This makes it difficult for traditional neutron gamma detectors to achieve a sub-millisecond time resolution of 0.1ms. Second, the measurement dynamic range is narrow, making it only suitable for neutron gamma measurements in a small number of scenarios in the radiation field of a fusion device. Summary of the Invention

[0005] The purpose of this application is to overcome the problems of the prior art by disclosing a neutron-gamma detector with high dynamic range and temporal resolution. The detector utilizes multiple layers of neutron moderators to form a gradient of neutron and gamma-ray detection efficiency for each layer of scintillator. A neutron-gamma-sensitive scintillator array, coupled with a photomultiplier tube array and a preamplifier array, measures a pulse count matrix from which the neutron and gamma count rates at each detector layer are extracted. By increasing the number of scintillators, the detector count rate is increased, thereby improving the temporal resolution. By increasing the number of layers in the neutron-gamma-sensitive scintillator array and the detection efficiency gradient between adjacent layers, the dynamic range is increased.

[0006] The purpose of this application is achieved through the following technical solutions: A neutron gamma detector with high dynamic range and time resolution, comprising: a plurality of detection units, a plurality of neutron moderators and a detector housing; Each detection unit is arranged along the axis of the detector housing, and a neutron moderator is provided between each detection unit. The detection unit comprises: a neutron / gamma sensitive scintillator array, a photomultiplier tube array, and a preamplifier array, and each layer of the neutron / gamma sensitive scintillator array is matched with one layer of the photomultiplier tube array and one layer of the preamplifier array.

[0007] According to a preferred embodiment, each neutron / gamma-sensitive scintillator in the neutron / gamma-sensitive scintillator array includes: a combination of LiF / ZnS scintillator and NaI(Tl) scintillator, or a combination of Li-6 and Li-7 lithium glass scintillators, or a combination of a plastic scintillator and Li-6 lithium glass scintillator, or a combination of semiconductor materials.

[0008] According to a preferred embodiment, the neutron moderator is made of the following materials, including: paraffin wax, boron carbide composite material, water-based moderator, and polyethylene material; Furthermore, the cross-sectional size of the neutron moderator is larger than the size of the neutron / gamma-sensitive scintillator array.

[0009] According to a preferred embodiment, the neutron / gamma-sensitive scintillator array includes two square lithium glass scintillators of the same size, Li-6 and Li-7, which are closely arranged on the same plane, and the two lithium glass scintillators, Li-6 and Li-7, are arranged adjacent to each other in the transverse direction or oblique direction.

[0010] According to a preferred embodiment, the front end and side surfaces of each scintillator in the neutron / gamma-sensitive scintillator array are covered with a scintillation light reflecting layer, so that each scintillator is an independent individual.

[0011] According to a preferred embodiment, the photomultiplier tube array matches the size of the neutron / gamma-sensitive scintillator array, and a scintillation light reflecting layer is provided on the side of the photomultiplier tube in the photomultiplier tube array corresponding to each scintillator in the neutron / gamma-sensitive scintillator array. The photomultiplier tube and the corresponding scintillator are integrally packaged, so that the photomultiplier tube array can convert the scintillation light signal generated by each scintillator into an electrical signal for independent output.

[0012] According to a preferred embodiment, the preamplifier array matches the photomultiplier tube array, can independently power each photomultiplier tube in the photomultiplier tube array, and can also amplify the signal generated by each channel silicon photomultiplier tube and output it independently.

[0013] According to a preferred embodiment, a plurality of heat sinks are provided on the inner side of the detector housing, and each heat sink is correspondingly arranged at the position of each detection unit to achieve heat dissipation of each detection unit.

[0014] According to a preferred embodiment, a detector positive mark is provided at the neutron-gamma input end of the detector housing, and the positive mark is a square groove structure, and the size of the square groove is equivalent to the area corresponding to the neutron / gamma-sensitive scintillator array; The detector housing is provided with input and output interfaces matching the preamplifier array.

[0015] According to a preferred embodiment, the interior of the detector housing further includes a wire trough and a circuit board slot; The wire duct is used to connect the detection unit and the input and output interface, so that after the external electronic system is connected to the input and output interface, the signal data obtained by the detection unit can be collected and processed; The circuit board slot is used to fix the detection unit and matches the wire slot interface so that each channel signal of the detection unit can be connected to the wire slot.

[0016] The aforementioned main solution of this application and its further options can be freely combined to form multiple solutions, all of which can be adopted and protected by this application. After understanding the solution of this application, those skilled in the art will understand that there are many combinations based on existing technology and common knowledge, all of which are technical solutions to be protected by this application, and these are not exhaustive here.

[0017] Beneficial effects of this application: The present invention effectively solves the problem of easy saturation of neutron and gamma detector signals in fusion experiments. The detector has a certain neutron energy spectrum measurement capability and is insensitive to magnetic fields. It is particularly suitable for measuring neutron and gamma count rates in high-intensity radiation fields of fusion experimental devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the neutron gamma detector with high dynamic range and time resolution of the present application; Figure 2 Schematic diagram of the arrangement of the neutron / gamma sensitive scintillator array of the present application when the neutron / gamma sensitive scintillator array is a lithium glass scintillator array (Li-6 scintillator and Li-7 scintillator use different colors); Figure 3 Three-view of the neutron gamma detector with high dynamic range and time resolution of the present application; Figure 4 Exploded view of the neutron gamma detector with high dynamic range and time resolution of the present application; Figure 5 Oblique view of the outer shell of the neutron gamma detector with high dynamic range and time resolution of the present application; Figure 6 Top view of the outer shell of the neutron gamma detector with high dynamic range and time resolution of the present application (semi-transparent view); Figure 7 Three-view of the detection unit of the neutron gamma detector with high dynamic range and time resolution of the present application; Wherein, 1 - detector cover plate, 2 - detection unit, 21 - neutron / gamma sensitive scintillator array, 22 - photomultiplier tube array, 23 - preamplifier array, 3 - neutron moderator, 4 - heat sink, 5 - detector outer shell, 51 - detector front mark, 52 - wire slot, 53 - circuit board slot, 54 - input / output interface. DETAILED DESCRIPTION

[0019] The specific embodiments of the present application are described below by way of specific examples. Those skilled in the art can easily understand other advantages and effects of the present application from the disclosure of the present specification. The present application can also be implemented or applied by other different specific embodiments, and the details in the present specification can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be noted that the following examples and features in the examples can be combined with each other without conflict.

[0020] It should be noted that similar reference numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0021] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of this application is typically placed when in use. These terms are intended only to facilitate the description of this application and simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0022] Furthermore, terms such as "horizontal," "vertical," and "overhanging" do not necessarily imply that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0023] It should also be noted that, in the description of this application, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0024] In addition, the present application would like to point out that, in the present application, unless the specific structures, connection relationships, positional relationships, power source relationships, etc. are specifically written out, the structures, connection relationships, positional relationships, power source relationships, etc. involved in the present application are all known to those skilled in the art based on the existing technology without creative work.

[0025] refer to Figures 1 to 7 The present application discloses a neutron gamma detector with high dynamic range and time resolution, wherein the neutron gamma detector comprises: a detector cover 1, several layers of detection units 2, several neutron moderators 3, a heat sink 4 and a detector housing 5.

[0026] Each detection unit 2 is arranged along the axis of the detector housing 5, and a neutron moderator 3 is provided between each detection unit 2. The detection unit 2 includes: a neutron / gamma-sensitive scintillator array 21, a photomultiplier tube array 22, and a preamplifier array 23, and each layer of the neutron / gamma-sensitive scintillator array 21 is matched with one layer of the photomultiplier tube array 22 and one layer of the preamplifier array 23.

[0027] This application utilizes a stack of multiple layers of detection units (neutron / gamma-sensitive scintillator array 21 + photomultiplier tube array 22 + preamplifier array 23), with neutron moderators placed between adjacent layers to create a neutron detection efficiency gradient. This gradient response matrix is ​​then used to calculate the neutron / gamma count rate, thus overcoming the saturation limitations of single-layer detectors. This design is applicable to any radiation detection scenario requiring saturation resistance, and the dynamic range is increased to 5 orders of magnitude or greater. Furthermore, the use of multiple layers of neutron moderators results in an exponential decay of neutron detection efficiency (e.g., 60% for the first layer, 30% for the second layer, and 15% for the third layer), constructing a nonlinear response matrix to avoid complete saturation. This results in an increase in the number of layers and gradient adjustment, thereby improving the dynamic range.

[0028] Each heat sink 4 is disposed inside the detector housing 5 . Specifically, each heat sink 4 is correspondingly disposed at the position of each detection unit 2 to achieve heat dissipation of each detection unit 2 .

[0029] The neutron / gamma input end of the detector housing 5 is provided with a detector positive mark 51. The detector positive mark 51 is a square groove structure, and the size of the square groove is equivalent to the area corresponding to the neutron / gamma-sensitive scintillator array 21. The detector housing 5 is provided with an input and output interface 54 that matches the preamplifier array 23.

[0030] The detector housing 5 also includes a wire slot 52 and a circuit board slot 53; the wire slot 52 is used to connect the detection unit 2 and the input and output interface 54, so that after the external electronic system is connected to the input and output interface 54, the signal data obtained by the detection unit 2 can be collected and processed; the circuit board slot 53 is used to fix the detection unit 2 and match the interface of the wire slot 52, so that each channel signal of the detection unit 2 can be connected to the wire slot 52.

[0031] Preferably, each neutron / gamma-sensitive scintillator in the neutron / gamma-sensitive scintillator array 21 can be: a combination of LiF / ZnS scintillator and NaI(Tl) scintillator, or a combination of Li-6 and Li-7 lithium glass scintillators, or a combination of plastic scintillator and Li-6 lithium glass scintillator, or a combination of semiconductor materials.

[0032] Preferably, the photomultiplier tube array 22 may be an avalanche photodiode (APD) array, or a traditional photomultiplier tube (PMT, which needs to be magnetically shielded) instead of SiPM.

[0033] Preferably, the neutron moderator 3 is made of the following materials: paraffin wax, boron carbide composite material, water-based moderator, polyethylene material. The cross-sectional dimensions of the neutron moderator 3 are larger than those of the neutron / gamma-sensitive scintillator array 21, and the thickness is adjustable.

[0034] Preferably, the front end and side surfaces of each scintillator in the neutron / gamma-sensitive scintillator array 21 are covered with a scintillation light reflecting layer, so that each scintillator is an independent individual.

[0035] Preferably, the photomultiplier tube array 22 matches the size of the neutron / gamma-sensitive scintillator array 21, and a scintillation light reflecting layer is provided on the side of the photomultiplier tube in the photomultiplier tube array 22 corresponding to each scintillator in the neutron / gamma-sensitive scintillator array 21. The photomultiplier tube and the corresponding scintillator are integrally packaged, so that the photomultiplier tube array 22 can convert the scintillation light signal generated in each scintillator into an electrical signal for independent output.

[0036] The isolated design of the scintillator's front and side reflective layers prevents optical crosstalk, improving the spatial resolution of neutron and gamma signals. Combined with multi-channel acquisition, it increases count rates (single-channel ≥5 Mcps) and achieves sub-millisecond temporal resolution (≤0.1ms). Preferably, the scintillator light reflective layer is made of materials such as TiO2, aluminum foil, and epoxy resin coating.

[0037] Preferably, the preamplifier array 23 is matched with the photomultiplier tube array 22, capable of independently powering each photomultiplier tube in the photomultiplier tube array 22 and amplifying the signal generated by each silicon photomultiplier tube channel for independent output. The multi-channel independent output characteristics of the preamplifier array 23 result in signal crosstalk less than 1%, supporting accurate pulse discrimination at high count rates and meeting the requirements for fast fusion process diagnosis.

[0038] Example 1 refer to Figure 1 As shown, this embodiment discloses a neutron gamma detector with high dynamic range and time resolution, which includes: a detector cover 1, several layers of detection units 2, several neutron moderators 3, a heat sink 4 and a detector housing 5.

[0039] Each detection unit 2 is arranged along the axis of the detector housing 5, and a neutron moderator 3 is provided between each detection unit 2. The detection unit 2 includes: a neutron / gamma-sensitive scintillator array 21, a photomultiplier tube array 22, and a preamplifier array 23, and each layer of the neutron / gamma-sensitive scintillator array 21 is matched with one layer of the photomultiplier tube array 22 and one layer of the preamplifier array 23.

[0040] In this embodiment, the neutron / gamma-sensitive scintillator array 21 utilizes a lithium glass scintillator array, including a combination of Li-6 and Li-7 lithium glass scintillators. The photomultiplier tube array 22 utilizes a silicon photomultiplier tube array (SiPM). The neutron moderator 3 is made of polyethylene.

[0041] The detector uses a multi-layer neutron moderator 3 to form a gradient of neutron and gamma-ray detection efficiency of each layer of scintillator. The lithium glass scintillator array matched with the silicon photomultiplier tube array and the preamplifier array can measure and obtain a pulse count matrix, and then extract the neutron and gamma count rates at each layer of detectors.

[0042] Increasing the number of lithium glass scintillators can increase the detector's count rate, thereby improving temporal resolution. By increasing the number of layers in the lithium glass scintillator array and the gradient of detection efficiency between adjacent layers, the dynamic range can be increased. This effectively addresses the problem of neutron and gamma detector signal saturation in fusion experiments. Furthermore, the detector has a certain neutron energy spectrum measurement capability and is insensitive to magnetic fields, making it particularly suitable for measuring neutron and gamma count rates in the high-intensity radiation fields of fusion experimental devices.

[0043] refer to Figure 2 As shown, the neutron / gamma-sensitive scintillator array 21 described in this embodiment includes two square lithium glass scintillators of the same size, Li-6 and Li-7, which are closely arranged on the same plane. The number of Li-6 and Li-7 lithium glass scintillators can be determined according to actual conditions, and the Li-6 and Li-7 lithium glass scintillators are required to be adjacent to each other in the horizontal or oblique direction. The front end and side surfaces of each scintillator are covered with a scintillation light reflecting layer, so that each scintillator is an independent individual and the scintillation light generated cannot enter other scintillators.

[0044] like Figure 3 As shown, the detector consists of a detector cover 1 and a detector housing 5, both 2 mm thick. To distinguish the detector's orientation, a square groove, designated as the detector forward marker 51, is cut on the side of the detector housing facing the device. The square groove is sized to correspond to the area corresponding to the neutron / gamma-sensitive scintillator array 21 and is 1 mm deep.

[0045] like Figure 4 As shown, the detector primarily consists of multiple detection units 2, multiple layers of neutron moderators 3, and multiple heat sinks 4. The detection units 2 detect neutrons and gamma rays, while the neutron moderators 3 moderate neutrons. The alternating arrangement of the two allows different layers of detection units to respond differently to neutrons and gamma rays, thereby expanding the detector's dynamic range and providing a certain degree of energy spectrum resolution. The heat sinks 4 dissipate heat released by each detection unit 2 out of the detector, thereby maintaining a constant temperature within a certain range.

[0046] The neutron moderator 3 described in this embodiment is made of high-density polyethylene and is circular or square in shape. Its size is larger than that of the neutron / gamma-sensitive scintillator array 21, and its thickness and density can be determined based on actual conditions. Each layer of neutron moderator 3 is arranged between every two adjacent detection units, starting from the second detection unit 2.

[0047] Figure 5 and Figure 6 The internal structure of the detector housing 5 is shown, including a wire slot 52, a circuit board slot 53, and an input / output interface 54. The wire slot 52 connects the detection unit 2 to the input / output interface 54, allowing an external electronic system to collect and process signal data from the detection unit. The circuit board slot 53 secures the detection unit and mates with the wire slot 52 interface, allowing each channel signal from the detection unit 2 to be connected to the wire slot 52.

[0048] like Figure 7 As shown, the detection unit 2 includes a neutron / gamma-sensitive scintillator array 21, a photomultiplier tube array 22, and a preamplifier array 23. Each layer of the neutron / gamma-sensitive scintillator array 21 is matched with a layer of photomultiplier tube array 22 and a layer of preamplifier array 23. The photomultiplier tube array 22 matches the size of the neutron / gamma-sensitive scintillator array 21. A scintillation light reflection layer is installed on the side of the photomultiplier tube array 22 corresponding to each lithium glass scintillator. The layer is encapsulated with the corresponding lithium glass scintillator to prevent scintillation light from entering other photomultiplier tube arrays 22. This allows the photomultiplier tube array 22 to convert the scintillation light signal generated by each lithium glass scintillator into an electrical signal for independent output. The preamplifier array 23 matches the photomultiplier tube array 22, not only providing power to the silicon photomultiplier tubes, but also amplifying the signal generated by each channel of the silicon photomultiplier tubes for independent output, without interference between channels.

[0049] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A neutron gamma detector with high dynamic range and time resolution, characterized in that The neutron gamma detector comprises: a plurality of detection units (2), a plurality of neutron moderators (3) and a detector housing (5); Each detection unit (2) is arranged along the axis of the detector housing (5), and a neutron moderator (3) is provided between each detection unit (2). The detection unit (2) comprises: a neutron / gamma-sensitive scintillator array (21), a photomultiplier tube array (22), and a preamplifier array (23), and each layer of the neutron / gamma-sensitive scintillator array (21) is matched with one layer of the photomultiplier tube array (22) and one layer of the preamplifier array (23).

2. The neutron gamma detector with high dynamic range and time resolution according to claim 1, characterized in that Each neutron / gamma-sensitive scintillator in the neutron / gamma-sensitive scintillator array (21) comprises: a combination of a LiF / ZnS scintillator and a NaI(Tl) scintillator, or a combination of two lithium glass scintillators, Li-6 and Li-7, or a combination of a plastic scintillator and a Li-6 lithium glass scintillator, or a combination of semiconductor materials.

3. The neutron gamma detector with high dynamic range and time resolution according to claim 1, characterized in that The neutron moderator (3) is made of the following materials: paraffin wax, boron carbide composite material, water-based moderator, and polyethylene material; Furthermore, the cross-sectional size of the neutron moderator (3) is larger than the size of the neutron / gamma-sensitive scintillator array (21).

4. The neutron gamma detector with high dynamic range and time resolution according to claim 1, wherein: The neutron / gamma-sensitive scintillator array (21) comprises two square lithium glass scintillators of the same size, Li-6 and Li-7, which are closely arranged on the same plane, and the two lithium glass scintillators, Li-6 and Li-7, are arranged adjacent to each other in the transverse direction or in an oblique direction.

5. The neutron gamma detector with high dynamic range and time resolution according to claim 1 or 4, characterized in that: The front end and side surfaces of each scintillator in the neutron / gamma-sensitive scintillator array (21) are covered with a scintillating light reflecting layer, so that each scintillator is an independent individual.

6. The neutron gamma detector with high dynamic range and time resolution according to claim 5, characterized in that: The photomultiplier tube array (22) matches the size of the neutron / gamma sensitive scintillator array (21). Furthermore, a scintillation light reflecting layer is provided on the side of the photomultiplier tube in the photomultiplier tube array (22) corresponding to each scintillator in the neutron / gamma sensitive scintillator array (21). The photomultiplier tubes are integrally packaged with corresponding scintillators, so that the photomultiplier tube array (22) can convert the scintillation light signal generated in each scintillator into an electrical signal for independent output.

7. The neutron gamma detector with high dynamic range and time resolution according to claim 6, characterized in that: The preamplifier array (23) matches the photomultiplier tube array (22), can independently power each photomultiplier tube in the photomultiplier tube array (22), and can also amplify the signal generated by each channel silicon photomultiplier tube and output it independently.

8. The neutron gamma detector with high dynamic range and time resolution according to claim 1, wherein: A plurality of heat sinks (4) are provided on the inner side of the detector housing (5), and each heat sink (4) is correspondingly arranged at the position of each detection unit (2) to achieve heat dissipation of each detection unit (2).

9. The neutron gamma detector with high dynamic range and time resolution according to claim 1, characterized in that: A detector positive mark (51) is provided at the neutron-gamma input end of the detector housing (5), and the positive mark (51) is a square groove structure, and the size of the square groove is equivalent to the area corresponding to the neutron / gamma-sensitive scintillator array (21); and an input and output interface (54) matching the preamplifier array (23) is provided on the detector housing (5).

10. The neutron gamma detector with high dynamic range and time resolution according to claim 9, characterized in that: The detector housing (5) further includes a wire trough (52) and a circuit board slot (53) inside; The wire slot (52) is used to connect the detection unit (2) and the input / output interface (54), so that after the external electronic system is connected to the input / output interface (54), the signal data obtained by the detection unit (2) can be collected and processed; The circuit board slot (53) is used to fix the detection unit (2) and matches the interface of the wire slot (52), so that each channel signal of the detection unit (2) can be connected to the wire slot (52).

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