Diffusion cloud chamber
Patent Information
- Application Number
- JP2022034008
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2022-03-07
- Publication Date
- 2025-02-19
- Estimated Expiration
- 2042-03-07
AI Technical Summary
Existing diffusion cloud chambers require powerful cooling means to achieve a temperature gradient for supersaturated states, leading to large, expensive, and difficult-to-handle equipment due to the need for large heat sinks and high power consumption.
A diffusion cloud chamber design utilizing a thermoelectric element and a cold material with a flat cooling plate and insulating material to create a stable temperature gradient, reducing the need for large heat sinks and power consumption.
The design allows for stable, accurate, and cost-effective observation of charged particle tracks with a simpler, more manageable setup compared to conventional methods.
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a fog chamber, which is a device for detecting the tracks of charged particles by using the condensation effect of steam, and particularly to a diffusion fog chamber that creates a supersaturated state by creating a temperature gradient inside an observation tank.
Background Art
[0002] In science experiments in schools and other educational institutions, fog chambers, particularly diffusion fog chambers that can be easily observed, are used to observe the tracks of charged particles such as natural radiation. The principle of the fog chamber is that when charged particles or radiation are incident on a supersaturated gas, which is a state containing more steam than the saturated steam amount (the maximum amount of steam that a gas can contain), ionization of gas molecules occurs, and droplets are generated using these ions as condensation nuclei. By illuminating this state with light and taking a photograph, the movement of the radiation can be seen as a line (the track of the radiation).
[0003] The diffusion fog chamber generates a temperature gradient (the upper part is warm and the lower part is cold) in the fog chamber to artificially create a supersaturated state. Specifically, water or alcohol is heated and evaporated above, and at the same time, the bottom surface of the box is cooled to about -3°C by a cooling means. In this state, the steam moves downward and is cooled to become a liquid, but during this process, a supersaturated region appears. Charged particles incident here are observed.
[0004] The diffusion fog chamber needs to have a powerful cooling means to create a low temperature state of about -30°C. However, considering the use in science experiments in educational institutions, it is desirable that the cooling means has a simple structure, is easy to handle, and is inexpensive.
Prior Art Documents
Patent Documents
[0005]
Patent Document 1
Summary of the Invention
[0006] To observe radiation trajectories in a diffusion cloud chamber, the temperature of the bottom surface must be lowered to at least -30°C. Dry ice and liquid nitrogen have been used as cooling methods for this purpose, but not only is their preparation difficult, but it has also been challenging to create a stable temperature gradient. Coolants capable of cooling down to -20°C have appeared, but it is still difficult to lower the temperature to -30°C, making stable observation difficult.
[0007] To improve upon these points, Patent Document 1 uses a Peltier element, which is a thermoelectric element, as a cooling method. However, lowering the temperature to below -30°C using a Peltier element requires a large power supply and a large heat sink, leading to the problem of larger and more expensive equipment. In a Peltier element, the heat absorbed on the absorption side plus the heat generated by the power consumption is produced on the dissipation side, so this heat on the dissipation side needs to be dissipated to the outside air or elsewhere by a heat dissipation means to cool it down. To cool to below -30°C, a large amount of heat needs to be removed from the observation area of the diffusion cloud chamber, so a powerful heat dissipation means is essential, and a larger heat sink is unavoidable. A larger heat sink leads to increased costs. In addition, the current consumption of the Peltier element is large for the transfer of a large amount of heat, so a large power supply is essential. The increased current consumption leads to further increases in the size of the heat sink and the cost of the power supply.
[0008] This invention was made to solve the above-mentioned problems, and aims to provide a diffusion cloud chamber that is simple in structure, easy to handle, allows for stable observation, and is inexpensive. [Means for solving the problem]
[0009] The diffusion cloud chamber according to this invention is A diffusion cloud chamber comprising an observation tank for observing the tracks of incident charged particles and a cooling tank located below the observation tank for cooling the observation tank, A steam generating means for generating steam is provided at the top of the observation tank. The bottom of the observation chamber is provided with an observation surface located approximately in the center and a bottom plate surrounding the observation surface. The upper part of the cooling tank is provided with a thermoelectric element located below the observation surface and in contact with the observation surface with a small thermal resistance, which transfers heat from above downwards; an intermediate insulating material located below the bottom plate; and a cooling plate located below the thermoelectric element and in contact with the thermoelectric element with a small thermal resistance, which receives heat from the thermoelectric element. The lower part of the cooling tank is provided with a cooling material whose upper surface is in contact with the cooling plate to cool it, and a lower insulating material located below the cooling material to insulate the cooling material. The lower insulating material may be elastic and bias the cold material toward the cooling plate.
[0010] The thermoelectric element is approximately the same size as the observation surface and smaller than the cooling plate. The cooling plate is a flat plate without any irregularities (specifically, without fins), The cooling material is approximately the same size as the cooling plate and approximately the same size as the inner diameter of the cooling tank. The cooling plate and the cooling material should preferably be as large as possible. They can fill the inner diameter of the observation tank and / or the cooling tank. [Effects of the Invention]
[0011] According to this invention, the combination of the thermoelectric element and the coolant makes it easier to handle compared to using conventional dry ice or liquid nitrogen, allows for more stable observation compared to using conventional coolants alone, and provides a less expensive diffusion cloud chamber compared to using conventional Peltier elements alone. [Brief explanation of the drawing]
[0012] [Figure 1] This is a perspective view of a diffusion cloud chamber according to an embodiment of the present invention. [Figure 2] This is a perspective view showing the components of the diffusion cloud chamber. [Figure 3]This is a perspective view (photograph) showing the usage of the diffusion cloud chamber. [Figure 4] This is a cross-sectional perspective view of the same diffusion cloud chamber when cut in a vertical plane. [Figure 5] This is a cross-sectional view of the same diffusion cloud chamber when cut vertically. [Figure 6] This is an exploded perspective view showing the bottom plate of the observation chamber, the insulation material of the cooling chamber, the thermoelectric element, and the cooling plate of the diffusion cloud chamber. [Figure 7] This is a schematic cross-sectional view of the same diffusion cloud chamber when cut in a vertical plane. [Modes for carrying out the invention]
[0013] Embodiments of the invention will be described with reference to the drawings.
[0014] As can be seen from Figures 1 and 2, the diffusion cloud chamber according to the embodiment of the invention comprises an observation tank 1 for observing the tracks of incident charged particles, a cooling tank 2 located below the observation tank 1 and including a cooling means 22 for cooling the observation tank 1, an LED lighting stand 3 for illuminating the inside of the observation tank 1, a control unit 4 for turning on and off the heaters of the cooling means 22, the LED lighting stand 3, and the steam generating means 12 described later, and a power supply unit 5 for supplying current to them. The cooling means 22 and heater and the control unit 4 are connected by connecting cables (wires) 21 and 41. The LED lighting stand 3 and the control unit 4 are connected by cables (wires) not shown. A power cable 51 is connected to the control unit 4, and current is supplied from the power supply unit 5. A transparent upper cap 7 is attached to the top surface of the observation tank 1. A translucent lower cap 8 is attached to the bottom surface of the cooling tank 2. The LED unit 31 of the LED lighting stand 3 is a unit (such as an LED tape) consisting of multiple LEDs arranged in a linear fashion, and is lit only on the misty area, and not on the bottom plate of the observation tank 1, so that the mist can be easily observed.
[0015] Figure 3 shows the diffusion fog box of the present case when the cooling means 22 and the LED lighting stand 3 are turned on. The inside of the observation tank 1 is brightly illuminated by the LED lighting stand 3, and it can be seen that the inside is cooled and frost has formed. A part of the side surface of the observation tank 1 is made of a transparent member (see reference numeral 1a in FIG. 4). The temperature at the lower part of the observation tank 1 is cooled to about -30°C by the cooling means 22, and a temperature gradient is generated between the upper part and the lower part. When water or alcohol is heated and evaporated by the steam generating means 12 described later, the steam goes downward and is cooled to become a liquid, and a supersaturated state region appears during this process. The radiation source 6 (for example, natural mineral uraninite) is inserted from the radiation source insertion port 11 provided on the side surface of the observation tank 1 near the supersaturated state region. Then, the tracks of charged particles can be observed in the observation range (above the cooling means 22) (see reference numeral A in FIG. 7). The radiation source 6 is attached to the tip of a metal radiation source holding rod 61. When not in use, it is covered with a metal protective cap 62.
[0016] Next, referring to FIGS. 4 to 7, the cross-sectional structure of the diffusion fog box of the present case and its cooling method will be further described. For convenience of explanation, each dimension of the elements in FIG. 7 is slightly deformed and does not match FIG. 5 in terms of size. The arrows in FIG. 7 indicate the flow of heat.
[0017] Above the observation tank 1, a steam generating means 12 for generating steam of water or alcohol is provided. The steam generating means 12 includes a sponge for soaking water or alcohol and a heater for generating steam, and is provided inside the observation tank 1 so as to discharge the steam into the observation tank 1.
[0018] At the bottom of the observation tank 1, an observation surface 14 is provided at substantially the center thereof, and an observation tank bottom plate 13 is provided so as to cover the portion other than the observation surface 14. A black anodized aluminum seal 29 is used for the observation surface 14 so that the tracks of charged particles can be easily observed and efficiently cooled. The surface of the observation tank bottom plate 13 is also black. From the viewpoint of cooling efficiency, it is preferable to make the observation surface 14 corresponding to the observation range A in FIG. 7 as small as possible within a range that does not hinder the observation.
[0019] At the top of the cooling tank 2, thermoelectric elements (Peltier elements) 22U and 22L are provided, which are cooling means 22 located below the observation surface 14, in contact with the observation surface 14 with low thermal resistance, and transferring heat from above downwards. The two thermoelectric elements 22U and 22L are stacked. Furthermore, an insulating material (intermediate insulating material) 24 is located below the bottom plate 13 of the observation tank, and an aluminum heat dissipation plate (cooling plate) 25 is located below the thermoelectric element 22L, in contact with the thermoelectric element 22L with low thermal resistance, and receives heat from the thermoelectric element 22L. A heat dissipation silicone adhesive 23 is applied between the two thermoelectric elements 22U and 22L, and between the thermoelectric element 22L and the heat dissipation aluminum plate 25 to enhance thermal conductivity between them. The insulating material 24 is to prevent the absorption of excess heat from parts unrelated to observation. Therefore, the thermal resistance between the observation tank bottom plate 13 and the heat dissipation aluminum plate 25 is high.
[0020] At the bottom of the cooling tank 2, there is a cooling material (cooling agent) 26 whose upper surface is in contact with the heat-dissipating aluminum plate 25 to cool it, and sponges 27U and 27L are provided below the cooling material 26 as lower insulating material to insulate the cooling material. The sponges 27U and 27L insulate the cooling material 26 so that heat is not transferred from the lower cap 8 on the bottom of the cooling tank 2 to the cooling material 26, and their elasticity presses the cooling material 26 toward the heat-dissipating aluminum plate 25 (biasing force). The cooling material 26 is capable of cooling to about -20°C. The size of the aluminum plate 25 and the cooling material 26 is important, and they are designed to be as large as possible, specifically to fill the inner diameter of the observation tank 1. Making them large facilitates the transfer of heat from the aluminum plate 25 to the cooling material 26, and by increasing the volume of the cooling material 26, the amount of heat it can absorb is increased.
[0021] If the surface area of the cooling plate receiving heat from the thermoelectric element 22L is not large enough, sufficient cooling effect cannot be obtained. Normally, fins are used to increase the surface area, but in this cooling tank 2, a cooling material is used, so the cooling plate needs to be flat and fins cannot be used (if fins are used, gaps and layers of air will be created between the cooling material and the cooling plate, preventing efficient heat conduction). Therefore, aluminum, which has high thermal conductivity, is used as the cooling plate, and a flat aluminum plate 25 with an area several times larger than that of the thermoelectric elements 22U and 22L is used. The cooling material 26 is a specially made product of a large size that can sufficiently cover the aluminum plate 25.
[0022] As shown in Figure 6, the observation tank bottom plate 13 is a disc approximately equal to the inner diameter of the observation tank 1, and a roughly square opening slightly smaller than the thermoelectric elements 22U and 22L is provided in its center. The insulation material 24 located beneath the observation tank bottom plate 13 has a similar shape to the observation tank bottom plate 13, but has cutouts to accommodate the thermoelectric elements 22U and 22L. The observation tank bottom plate 13, the insulation material 24, and the aluminum heat dissipation plate 25 are provided with four holes for assembly screws 28 surrounding the thermoelectric elements 22U and 22L. The observation tank bottom plate 13, the insulation material 24, and the aluminum heat dissipation plate 25 are assembled using the assembly screws 28, and the thermoelectric elements 22U and 22L are in close contact with the aluminum heat dissipation plate 25.
[0023] Next, I will explain how it works. When the control unit 4 turns on the cooling means 22 and the LED lighting stand 3, the LED lights up and the thermoelectric elements (Peltier elements) 22U and 22L are driven simultaneously. The current of the upper thermoelectric element 22U is made greater than the current of the lower thermoelectric element 22L. After about 5 minutes, the temperature of the upper part of the observation surface 14 of the observation tank 1 drops to about -30°C or lower. Remove the upper cap 7 and thoroughly soak the sponge of the vapor generating means 12 with alcohol (isopropyl alcohol IPA) or anhydrous ethanol, and evaporate it with the heater of the vapor generating means 12. Due to the action of the heater (not shown), steam is generated, and the temperature difference between the upper and lower cooled observation surfaces 14 inside the observation tank 1 increases, creating a supercooled state. In this state, the radiation source 6 is placed near the observation surface 14. Attach the upper cap 7 and observe from above the observation tank 1.
[0024] The arrows in Figure 7 indicate the flow of heat. The thermoelectric elements (Peltier elements) 22U and 22L absorb heat from the observation surface 14 and transfer it downwards to the heat-dissipating aluminum plate 25. Since aluminum has high thermal conductivity, the heat is transferred to the entire aluminum plate 25 and absorbed by the cooling agent 26 through its entire underside. Because the contact area between the aluminum plate 25 and the cooling agent 26 is large, heat transfer is efficient. The contact area between the thermoelectric element 22L and the aluminum plate 25 is smaller, but the presence of the heat-dissipating silicone adhesive 23 between them reduces thermal resistance, and heat transfer is still efficient. Since the insulating material 24 is present in the areas other than the thermoelectric elements 22U and 22L, heat does not transfer from the observation tank bottom plate 13, and heat is absorbed mainly by the observation surface 14. Therefore, only the observation area A corresponding to the observation surface 14 can be efficiently cooled. The cooling pack 26 is insulated by sponges 27U and 27L, so it primarily absorbs heat from the aluminum plate 25.
[0025] According to the embodiment of the invention, by making the aluminum plate 25 and the cooling agent 26 as large as possible, and the observation surface 14 as small as possible, the portion of the observation area A could be efficiently cooled. By including the cooling agent 26, a large heat sink was not required, resulting in a smaller size. In addition, power consumption could be reduced to a fraction of that when only a Peltier element was used. As a result, cost reduction was also possible.
[0026] According to the embodiment of the invention, it was easier to handle compared to using dry ice or liquid nitrogen. Compared to using only a cooling agent, it became possible to perform more stable observations.
[0027] This invention uses a general-purpose coolant capable of cooling down to approximately -20°C as the cooling component (a coolant that lowers the temperature of an object by contact). However, it is also possible to use a mixture of calcium chloride, magnesium chloride, sodium chloride, etc., with ice as the coolant. The coolant is packaged in a bag for easy handling. Moreover, it can be cooled in a standard freezer. The above effect can be achieved by making this material tightly attached to a flat cooling plate 25.
[0028] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the invention as described in the claims, and it goes without saying that these modifications are also included within the scope of the present invention. [Explanation of symbols]
[0029] 1 Observation Tank 1a LED light transmission part 11. Source insertion port 12 Steam generating means 13 Observation tank bottom plate 14. Observation surface (black anodized aluminum seal) 2 Cooling tank 21 Connection Cables 22 Cooling means 22U Upper Peltier element (thermoelectric element) 22L Lower Peltier element (thermoelectric element) 23. Silicone adhesive for heat dissipation 24. Insulation material (intermediate insulation material) 25. Aluminum heat dissipation plate (cooling plate) 26. Cooling pack (ice pack) 27U Upper sponge (Lower insulation) 27L Lower sponge (lower insulation material) 28 Assembly screws 29 Black anodized aluminum seal 3 LED lighting stand 31 LED units 4. Control Unit 41 Connection Cable 51 Power Cable 6 source 61 Source support rod 62 Protective caps 7. Top cap 8. Lower cap A Observation range
Claims
1. A diffusion cloud chamber including an observation tank for observing the tracks of incident charged particles and a cooling tank located below the observation tank for cooling the observation tank, a steam generating means for generating steam is provided at an upper portion of the observation tank; The bottom of the observation tank is provided with an observation surface located approximately at the center thereof and a bottom plate surrounding the observation surface, A thermoelectric element is provided in an upper portion of the cooling tank, the thermoelectric element being located below the observation surface and in contact with the observation surface with a small thermal resistance, and transferring heat from above downward; an intermediate insulating material is provided below the bottom plate; and a cooling plate is provided below the thermoelectric element, the intermediate insulating material is provided below the bottom plate, and the cooling plate is provided below the thermoelectric element, in contact with the thermoelectric element with a small thermal resistance, and receiving heat from the thermoelectric element. a cooling material having an upper surface in contact with the cooling plate and configured to cool the cooling plate, and a lower insulation member positioned below the cooling material and configured to insulate the cooling material, are provided at a lower portion of the cooling tank.
2. the thermoelectric element is approximately the same size as the observation surface and smaller than the cooling plate; The cooling plate is a plate-like plate having no irregularities, 2. The diffusion cloud chamber according to claim 1, wherein the cooling material has a size substantially equal to that of the cooling plate and an inner diameter substantially equal to that of the cooling tank.
3. 3. The diffusion cloud chamber according to claim 1, wherein the lower insulating material has elasticity and biases the cooling material toward the cooling plate.