Portable high-purity germanium detector with two-stage refrigeration structure

Abstract

The portable high-purity germanium detector with two-stage refrigeration structure comprises a detector body, a first detector shell arranged outside the detector body and separated from the detector body to form a first vacuum cavity, a second detector shell arranged outside the first shell and separated from the first shell to form a second vacuum cavity, a first refrigeration interface arranged between the first shell and the second shell and connected with the first shell and an external refrigerator to realize one-stage refrigeration, and a second refrigeration interface arranged on the second shell and connected with the first shell and a system refrigerator to realize two-stage refrigeration. The refrigeration process of the detector body and the first shell is divided into two stages, one-stage rapid refrigeration is realized through the first refrigeration interface, further two-stage refrigeration and long-time low-temperature maintenance are realized through the second refrigeration interface, and the refrigeration time is effectively shortened.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of detectors, and particularly relates to a portable high-purity germanium detector with a two-stage refrigeration structure. BACKGROUND

[0002] The energy of gamma rays can be used as a "fingerprint" to identify specific radioactive materials, so radioactive substances are usually detected and identified by detecting and identifying the gamma rays emitted by the to-be-detected substances. The high-purity germanium detector has good sensitivity and identification capability, and is one of the detectors with high resolution at present.

[0003] In order to ensure the band gap width of the high-purity germanium crystal, the working environment of the high-purity germanium detector needs to be maintained at a low temperature (lower than 100K) and a high static vacuum state. The traditional refrigeration technology includes liquid nitrogen refrigeration and electric refrigeration. The liquid nitrogen refrigeration needs to be matched with a dewar flask and the high-purity germanium detector, and the electric refrigeration needs to be matched with a high-power electric refrigeration engine. The detection system is complex and large in size, and is not convenient for outdoor portable use.

[0004] With the development of technology and the excavation of more application scenarios, new requirements for technological innovation are also put forward. For example, in the fields of national security and nuclear emergency, the high-purity germanium detector has a strategic position as one of the core components. Based on this, some uncertain accidents or emergency events require the use of high-purity germanium detectors in outdoor or even field scenarios. The existing portable high-purity germanium detectors are generally small in size to meet the scene. The liquid nitrogen refrigeration method has low integration with the high-purity germanium detector, which is not conducive to portability, and has the limitation of long refrigeration time due to the short use time of liquid nitrogen and the high filling frequency. On the other hand, the electric refrigeration method has the limitation of long refrigeration time due to the relatively small power of the backup battery. These will result in a long refrigeration time of the portable high-purity germanium detector, which is even more than 12 hours. The long waiting time is difficult to apply to specific outdoor and emergency scenarios.

[0005] Therefore, how to realize fast refrigeration is an important indicator of the portable high-purity germanium detector, an important guarantee for using in outdoor emergency events, and one of the technical difficulties to be solved in the field. SUMMARY

[0006] Therefore, the embodiment of the application provides a portable high-purity germanium detector with a two-stage refrigeration structure to realize fast refrigeration of the detector and apply it to outdoor emergency scenarios.

[0007] The portable high-purity germanium detector with two-stage refrigeration structure comprises a detector body, a first detector shell arranged outside the detector body and separated from the detector body to form a first vacuum cavity, a second detector shell arranged outside the first shell and separated from the first shell to form a second vacuum cavity, a first refrigeration interface provided between the first shell and the second shell and connecting the first shell with an external refrigeration device to realize first-stage refrigeration, and a second refrigeration interface provided on the second shell and connecting the first shell with a system refrigeration device to realize second-stage refrigeration.

[0008] In an embodiment, the first refrigeration interface comprises a first cold finger, a blocking tube and a blocking plug.

[0009] One end of the first cold finger is physically connected with the first shell, and the other end of the first cold finger is arranged on the second shell and used for connecting with an external high-power refrigeration device; two ends of the blocking tube are fixed on the first shell and the second shell respectively; and the blocking plug is in interference fit with the pipe diameter of the blocking tube, the first cold finger extends into the blocking plug, the blocking tube and the first shell are connected, the blocking tube and the blocking plug separate the second vacuum cavity from the first cold finger and external space, and the second vacuum cavity has a high vacuum degree.

[0010] In an embodiment, the second refrigeration interface comprises a second cold finger and a heat-conducting member; one end of the second cold finger extends into the second vacuum cavity through the second shell and is fixedly connected with the first shell; the other end of the second cold finger is connected with a system refrigeration device; one end of the heat-conducting member is fixedly connected with the end of the second cold finger extending into the second vacuum cavity, and the other end of the heat-conducting member is fixedly connected with the first shell.

[0011] In an embodiment, a structured mounting assembly is arranged between the first shell and the second shell; the structured mounting assembly comprises pin-point tie rods arranged at opposite ends of the first shell and the second shell respectively.

[0012] In an embodiment, the structured mounting assembly further comprises a tie member; the pin-point tie rods are arranged in pairs on the first shell and the second shell, and the pin-point tie rods are tensioned by the tie member.

[0013] In an embodiment, a low-radiation infrared reflective coating is further included; the first shell and the second shell of the detector are respectively provided with the low-radiation infrared reflective coating on the inner wall and the outer wall of the first shell and the inner wall of the second shell to prevent heat radiation.

[0014] In an embodiment, an adsorption layer is further included; the adsorption layer is arranged in the radial direction of the second shell to adsorb residual gas in the second vacuum cavity.

[0015] In an embodiment, the pin-point tie rod is a conductive screw.

[0016] In an embodiment, the tie member is a Kevlar line.

[0017] In an embodiment, the sealing tube is a vacuum bellows.

[0018] The two-stage refrigeration structure portable high-purity germanium detector provided by the embodiment of the present application creatively divides the refrigeration process of the detector body and the first shell of the detector into two stages, realizes one-stage rapid refrigeration through the first refrigeration interface connected with an external high-power refrigerator, realizes further two-stage refrigeration and long-time low-temperature maintenance through the second refrigeration interface connected with a system refrigerator, and finally effectively shortens the overall refrigeration time of the portable high-purity germanium detector and prolongs the use time of the detector body.

[0019] Compared with the direct refrigeration mode generally adopted in the prior art, the refrigeration time is shortened from about 12 hours to about 6 hours, the refrigeration efficiency is greatly improved, the portable use in outdoor scenes can be better adapted, sudden or emergency events can be responded to, and emergency radiation monitoring can be facilitated. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0021] Figure 1 is a structure schematic diagram of the two-stage refrigeration structure portable high-purity germanium detector of the embodiment of the present application;

[0022] Figure 2 is Figure 1 is a first refrigeration interface structure schematic diagram of the embodiment partially enlarged;

[0023] Figure 3 is Figure 1 is a structural mounting member schematic diagram of the first shell and the second shell of the detector. DETAILED DESCRIPTION

[0024] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0025] In order to illustrate the technical solutions of the two-stage refrigeration structure portable high-purity germanium detector according to the present application, the following specific embodiments are described.

[0026] The following refers to Figures 1-3 According to the embodiments of the present application, the two-stage refrigeration structure portable high-purity germanium detector 1000 comprises a detector body 10, a detector first shell 20 and a detector second shell 30, a first refrigeration interface 40 and a second refrigeration interface 50, and a system refrigerator 60.

[0027] The detector body 10 is mainly made of a germanium crystal and is the core component of the detector and the core component that needs to be cooled, and is used for detecting nuclear radiation.

[0028] The detector first shell 20 is arranged outside the detector body 10 and is separated from the detector body 10 to form a first vacuum cavity 201. The first vacuum cavity 201 is in a vacuum state, and the detector body 10 is placed therein, which is equivalent to covering the detector body 10 with a vacuum layer, which can provide a high-vacuum ultra-clean working environment for the detector body 10 and also play a role in thermal insulation.

[0029] The detector second shell 30 is arranged outside the detector first shell 20 and is separated from the detector first shell 20 to form a second vacuum cavity 301. The second vacuum cavity 301 is in a vacuum state, and the detector first shell 20 is placed therein, which is equivalent to covering the detector first shell 20 with a vacuum layer, which also plays a role in protection and thermal insulation.

[0030] The first vacuum cavity 201 and the second vacuum cavity 301 are two independent vacuum chambers, which can reduce the influence of the mechanical vibration of the high-power external refrigerator (not shown in the figure) and the system refrigerator 60 on the detector body 10, play a role in shock absorption, and maintain the performance indicators of the detector body 10.

[0031] The first refrigeration interface 40 includes a first cold finger 41, a blocking pipe 42 and a blocking plug 43. Specifically, the first refrigeration interface 40 is arranged between the first shell 20 and the second shell 30, and the first cold finger 41 is connected to a high-power external refrigerator to perform first-stage rapid refrigeration on the detector body 10 and the first shell 20. The first shell 20 and the second shell 30 are connected through the blocking pipe 42, and the blocking plug 43 is arranged at the connection between the blocking pipe 42 and the second shell 30. One end of the first cold finger 41 penetrates the blocking plug 43 to be connected to the high-power external refrigerator, and the other end of the first cold finger 41 penetrates the blocking plug 43 to extend into the blocking pipe 42 and physically contact the first shell 20.

[0032] Specifically, the blocking plug 43 is in interference fit with the pipe diameter of the blocking pipe 42, so as to separate the second vacuum cavity 301 from the blocking pipe 42 and the external space, so as to maintain the high vacuum degree of the second vacuum cavity 301, avoid pollution of the working environment of the detector body 10, and affect the performance indicators of the detector body 10. At the same time, the first cold finger 41 in the blocking pipe 42 is insulated and heat-insulated.

[0033] The second refrigeration interface 50 includes a second cold finger 51 and a heat-conducting member 52. Specifically, the second refrigeration interface 50 is arranged on the second shell 30, and the second cold finger 51 is connected to the system refrigerator 60 to perform second-stage refrigeration. The second cold finger 51 penetrates the second shell 30 and is fixedly welded. One end of the second cold finger 51 is connected to the system refrigerator 60, and the other end of the second cold finger 51 penetrates the second shell 30 to extend into the second vacuum cavity 301 and is fixedly connected to the first shell 20 through the heat-conducting member 52.

[0034] It should be noted that, during system assembly, the first vacuum cavity 201 and the second vacuum cavity 301 need to be vacuumized before packaging, so as to form a high-vacuum layer.

[0035] The two-stage refrigeration structure of the portable high-purity germanium detector 1000 of the present application includes a detector body 10 with detection capability, a detector first shell 20 and a detector second shell 30, and a new structure with a first refrigeration interface 40 and a second refrigeration interface 50 with rapid refrigeration capability. The refrigeration process of the detector body 10 and the detector first shell 20 is divided into two stages, one-stage rapid refrigeration is achieved by connecting an external high-power refrigerator (not shown in the figure) through the first refrigeration interface 40, and further two-stage refrigeration and long-time low-temperature maintenance are achieved by connecting a system refrigerator 60 through the second refrigeration interface 50. Ultimately, the overall refrigeration time of the portable high-purity germanium detector is effectively shortened, and the use time of the detector body 10 is prolonged. Compared with the direct refrigeration method commonly used in the prior art, the refrigeration time is shortened from about 12 hours to about 6 hours, the refrigeration efficiency is greatly improved, the portable use in outdoor scenes can be better adapted, sudden or emergency events can be handled, and it is beneficial to handle emergency radiation monitoring.

[0036] In an embodiment of the present application, the system refrigerator 60 is a Stirling electric refrigerator, and the high-power external refrigerator is a high-power Stirling electric refrigerator. The Stirling electric refrigerator is an electric refrigerator capable of maintaining the working temperature of the high-purity germanium detector.

[0037] The first refrigeration interface 40 connects the external high-power Stirling electric refrigerator through the first cold finger 41, and can rapidly refrigerate the detector body 10 and the detector first shell 20, rapidly reduce the temperature of the detector body 10 and the detector first shell 20 to a predetermined temperature, for example, near the working temperature 100K of the high-purity germanium detector.

[0038] When the portable high-purity germanium detector needs to work outdoors, the external refrigerator can be disconnected, and the system refrigerator 60 is used to further cool the detector body 10 and the detector first shell 20 to a stable working state through the second refrigeration interface 50, and maintain this temperature for a long time, which is beneficial to outdoor radiation detection use.

[0039] The portable high-purity germanium detector 1000 with two-stage refrigeration structure according to the present application, the refrigeration process of the detector body 10 and the detector first shell 20 is divided into two stages by the two refrigeration interfaces, the first refrigeration interface 40 and the second refrigeration interface 50. The first refrigeration interface 40 can quickly reduce the temperature of the detector body 10 and the detector first shell 20 to a predetermined temperature by connecting a high-power external refrigerator. After the external refrigerator is disconnected, the system refrigerator 60 and the second refrigeration interface 50 can continue to reduce the temperature of the detector body 10 and the detector first shell 20 to the working temperature of the high-purity germanium detector (for example, below 100K), and maintain the low temperature for a long time. This can effectively shorten the refrigeration time of the portable high-purity germanium detector, improve the working efficiency of the detector, prolong the outdoor portable use time of the detector, and reduce the influence of mechanical vibration of the refrigerator on the detector through the second vacuum cavity 301 to maintain the performance index of the detector body 10.

[0040] According to another embodiment of the present application, the structured mounting member 70 includes pin point struts (71, 72) and a tie member 73. The structured mounting member 70 suspends the detector first shell 20 on the detector second shell 30. Specifically, the outer wall of the detector first shell 20 is provided with a plurality of pin point tie rods 71 at both ends in the radial direction, and the inner wall of the detector second shell 30 is provided with a plurality of pin point tie rods 72 at both ends in the radial direction. The pin point tie rods 71 and the pin point tie rods 72 are arranged in pairs and are tensioned by the tie member 73. The pairs of pin point tie rods 71 and the pin point tie rods 72 can extend in the same or opposite directions to adjust the suspension mounting position of the detector first shell 20.

[0041] Further, the structured mounting member 70 has a total of eight pairs of pin point tie rods. Four pin point tie rods 71 are arranged at both ends of the outer wall of the detector first shell 20, and four pin point tie rods 72 are arranged at both ends of the inner wall of the detector second shell 30. The plurality of pin point tie rods 71 have a small spacing, and the plurality of pin point tie rods 72 have a large spacing. To fix the detector first shell 20 and prevent the detector first shell 20 from directly contacting the detector second shell 30, the plurality of pairs of tie rods 71 and tie rods 72 are tensioned by the tie member 73 to be coaxially fixed and positioned relative to each other.

[0042] In one embodiment, the tie member 73 is configured as a Kevlar line. The pin point tie rods 71 and the pin point tie rods 72 are the same structural features, and different structures can be selected for installation as needed. In addition, the pin point tie rods 71 and the pin point tie rods 72 are connected to the corresponding shell by conductive screws to produce a metal-to-metal connection. The thermal resistance performance of the tie member 73 connecting the plurality of tie rod pairs prevents the detector second shell 30 from generating heat diversion to the detector first shell 20.

[0043] The first detector shell 20 is non-contactingly suspended on the second detector shell 30, and can achieve the effects of impact resistance and heat insulation. The heat insulation is due to the effects of reducing heat conduction and low-emissivity infrared reflective coating. The perforation of the shell affects the heat insulation performance of the infrared reflective coating, and therefore the plurality of pin-point tie rods of the structured mounting member 70 of the present application are non-perforation-mounted, and the perforation of the shell of the two-stage refrigeration structure is minimized to maximize the heat insulation effect of the infrared reflective coating, so as to prolong the working time of the detector body 10.

[0044] It is worth noting that the portable high-purity germanium detector 1000 of the two-stage refrigeration structure of the present application can achieve overall low heat load without the need for auxiliary means for heat insulation protection. The surface area ratio of the second detector shell 30 and the first detector shell 20 is one of the key factors affecting the overall heat load of the system, and the present application minimizes the ratio of the surface area of the second detector shell 30 to the surface area of the first detector shell 20 to achieve overall low heat load of the system, rather than through auxiliary means for heat insulation.

[0045] According to another embodiment of the present application, the ratio of the inner surface area of the second detector shell 30 to the outer surface area of the first detector shell 20 is 1.5.

[0046] In addition, the first detector shell 20 and the second detector shell 30 further comprise a low-emissivity infrared reflective coating 80, which is arranged on the inner wall and the outer wall of the first detector shell 20 and on the inner wall of the second detector shell 30, to prevent heat leakage of the first detector shell 20 and the second detector shell 30. In the present embodiment, the low-emissivity infrared reflective coating 80 is configured as a high-polished gold coating.

[0047] According to one embodiment of the present application, the second detector shell 30 further comprises an adsorption layer 90 arranged in the radial direction of the inner wall of the second detector shell 30 to adsorb residual gas in the second vacuum cavity 301.

[0048] The first vacuum cavity 201 and the second vacuum cavity 301 are evacuated to high vacuum in the early packaging process, and the high vacuum environment needs to be maintained later. Since the parts between the first detector shell 20 and the second detector shell 30, such as the mounting member 70 and the low-emissivity infrared reflective coating 80, release trace amounts of gas, which can damage the core components of the detector body 10, the adsorption layer 90 is arranged in the second detector shell 30 to timely absorb the residual gas released by the parts in the second vacuum cavity 301, and finally achieve a vacuum cryogenic constant-temperature environment in the second shell.

[0049] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A portable high-purity germanium detector of two-stage refrigeration structure, characterized in that, The application relates to a detector, which comprises the following parts: a detector body; a detector first shell arranged outside the detector body and separated from the detector body to form a first vacuum cavity; a detector second shell arranged outside the first shell and separated from the first shell to form a second vacuum cavity; a first refrigeration interface arranged between the detector first shell and the detector second shell and connecting the first shell with an external refrigeration device to realize first-stage refrigeration; a second refrigeration interface arranged on the detector second shell and connecting the first shell with a system refrigeration device to realize second-stage refrigeration; the first refrigeration interface comprises a first cold finger, a blocking pipe and a blocking plug; one end of the first cold finger is physically connected with the first shell, and the other end of the first cold finger is arranged on the second shell and used for connecting with an external high-power refrigeration device; two ends of the blocking pipe are fixed on the detector first shell and the detector second shell respectively; and the blocking plug is in interference fit with the pipe diameter of the blocking pipe, the first cold finger extends into the blocking plug, the blocking pipe and the detector first shell are connected, the second vacuum cavity is separated from the first cold finger and external space by the blocking pipe and the blocking plug, and the second vacuum cavity has a high vacuum degree; the second refrigeration interface comprises a second cold finger and a heat-conducting member; one end of the second cold finger extends into the second vacuum cavity through the second shell and is fixedly connected with the first shell, and the other end of the second cold finger is connected with the system refrigeration device; one end of the heat-conducting member is fixedly connected with one end of the second cold finger extending into the second vacuum cavity, and the other end of the heat-conducting member is fixedly connected with the first shell. A structured mounting assembly is arranged between the detector first shell and the detector second shell; 2. The portable high-purity germanium detector of two-stage refrigeration structure according to claim 1, characterized in that, the structured mounting assembly comprises pin-point tie rods arranged at opposite ends of the detector first shell and the detector second shell respectively. The structured mounting assembly further comprises a tie member; 3. The portable high-purity germanium detector of two-stage refrigeration structure according to claim 2, characterized in that, the pin-point tie rods are arranged in pairs on the detector first shell and the detector second shell, and the pin-point tie rods are tensioned by the tie member. The detector further comprises a low-radiation infrared reflective coating; 4. The portable high-purity germanium detector of two-stage refrigeration structure according to claim 1 or 2, characterized in that, the detector first shell and the detector second shell respectively arrange the low-radiation infrared reflective coating on the inner wall and the outer wall of the detector first shell and the inner wall of the detector second shell to prevent heat radiation. The detector further comprises an adsorption layer arranged in the radial direction of the detector second shell to adsorb residual gas in the second vacuum cavity.

5. The portable high-purity germanium detector of two-stage refrigeration structure according to claim 4, characterized in that, The pin-point tie rods are conductive screws.

6. The portable high-purity germanium detector of two-stage refrigeration structure according to claim 5, characterized in that, The tie member is a Kevlar line.

7. The portable high-purity germanium detector of two-stage refrigeration structure according to claim 6, characterized in that, The blocking pipe is a vacuum bellows.

8. The portable high-purity germanium detector of two-stage refrigeration structure according to claim 7, characterized in that, ​

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