Cloud chamber

Abstract

To provide a portable type cloud chamber which can increase volume of the chamber, and increase a thickness of an excessively saturated steam layer for facilitating observation of a track of natural radiation.SOLUTION: There is provided a cloud chamber for observing a track of natural radiation which passes through an excessively saturated steam layer of ethanol, the cloud chamber comprising: an observation box whose top face is closed by a lid which has an observation window; steam generation means for forming the excessively saturated steam layer by evaporation of the ethanol put into the observation box; a heating glass provided on the observation window for warming, an upper part in an interior side of the observation box; a cooling plate which cools a lower part in the interior part of the observation box for forming a temperature gradient; and a refrigerator where a heat adsorption part is provided on the lower face of the cooling plate, where a center of the cooling plate is protruded downward, so as to cover the heat adsorption part of the refrigerator.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a portable cloud chamber that has an increased volume and a thicker supersaturated vapor layer, making it easier to observe the tracks of natural radiation. [Background technology]

[0002] A cloud chamber is a device for visualizing the tracks of charged particles using the condensation of vapor. A liquid such as alcohol is heated and evaporated in the upper part of the cloud chamber, and a temperature gradient is created by cooling the lower part of the cloud chamber, generating a supersaturated vapor layer. When radiation enters this layer, the gas is ionized and droplets are generated, and the radiation tracks can be observed by shining light on it.

[0003] Cloud chambers are installed as teaching materials in, for example, science museums, educational facilities, etc. The radiation to be observed in a cloud chamber is mainly alpha and beta rays that are generated when radon gas in the air naturally decays, but by increasing the volume of the cloud chamber, the amount of radon gas increases and the amount of radiation that can be observed also increases.

[0004] In addition, if the observation window of the cloud chamber is small, the wall of the cloud chamber blocks alpha rays from the outside, reducing the amount of observation. If the observation window is made larger, the cooling capacity must be increased accordingly, and a refrigerant gas circulation type refrigerator would make the entire cloud chamber larger, making it difficult to make it portable so that it can be moved around educational facilities.

[0005] As described in Patent Document 1, an invention has been disclosed for a cloud chamber that makes it easier to see the tracks of charged particles inside the container without causing burns to observers who come into contact with the device by lowering the temperature of the device. Furthermore, as described in Patent Document 2, an invention has been disclosed for a low-temperature diffusion cloud chamber that is lightweight and compact, and that uses an electronic cooling element to cool the inside of the observation chamber to keep the temperature difference between the top and bottom of the observation chamber at an optimal value, making it easy to observe many natural radiation tracks. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 09-184887 [Patent Document 2] Patent No. 4537332 Summary of the Invention [Problem to be solved by the invention]

[0007] As in Patent Documents 1 and 2, the use of a Peltier element can reduce the size and weight, but it is difficult to obtain sufficient cooling capacity for a large observation window. If the observation window is small, the amount of radon gas contained therein is also small, making it difficult to observe radiation, so radon gas is sometimes artificially injected into the cloud chamber to generate tracks, but this makes it difficult to say that naturally occurring radiation is being observed.

[0008] Therefore, an object of the present invention is to provide a portable cloud chamber that increases the volume of the cloud chamber and thickens the supersaturated vapor layer, making it easier to observe the tracks of natural radiation. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides a cloud chamber for observing the tracks of radiation passing through a supersaturated vapor layer of ethanol, comprising an observation box whose upper surface is covered with a lid having an observation window, a vapor generating means for evaporating ethanol placed in the observation box to form a supersaturated vapor layer, a heating glass provided in the observation window to heat an upper part of the observation box, a cooling plate arranged to cool a lower part of the observation box to create a temperature gradient, and a refrigerator with a heat absorption part abutted against the underside of the cooling plate, and the center of the cooling plate protrudes downward so as to cover the heat absorption part of the refrigerator.

[0010] The present invention also provides a cloud chamber for observing the tracks of radiation passing through a supersaturated vapor layer of ethanol, comprising an observation box whose upper surface is covered with a lid having an observation window, steam generating means for evaporating ethanol placed in the observation box to form a supersaturated vapor layer, heating glass provided in the observation window to heat an upper portion of the observation box, a cooling plate arranged to cool a lower portion of the observation box to create a temperature gradient, and a refrigerator with a heat absorption part abutted against the underside of the cooling plate, wherein the center of the cooling plate is recessed so as to cover the heat absorption part of the refrigerator.

[0011] In the cloud chamber, in order to uniformly cool the entire cooling plate, a groove is formed in the cooling plate so that ethanol accumulated on the upper surface of the cooling plate can be discharged to a recovery port of the observation box.

[0012] The cloud chamber is characterized in that it is provided with a circulation pump that supplies ethanol discharged from a recovery port of the observation chamber to the vapor generating means.

[0013] In the cloud chamber, ethanol discharged from a recovery port of the observation box is supplied to a tray of the vapor generating means by a pump utilizing capillary action.

[0014] In the cloud chamber, a high voltage is applied to a tray of the vapor generating means so as to suppress a decrease in the amount of vapor in the supersaturated vapor layer due to condensation of the ethanol vapor and to expand the supersaturated vapor layer. It is characterized by:

[0015] The cloud chamber is characterized in that it has a radiation source insertion / removal device for inserting a radiation source into the observation box from the outside.

[0016] In the cloud chamber, the refrigerator is a Stirling cycle refrigerator, and cools the cooling plate to -50 to -30°C. Effect of the Invention

[0017] According to the present invention, even if the housing is made small so that it can be moved around educational facilities, etc., by increasing the volume of the cloud chamber and thickening the supersaturated vapor layer in the observation chamber with a cooling capacity greater than or equal to that of a Peltier element, it becomes possible to adequately observe the tracks of natural radiation without the need to artificially introduce a radiation source. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a cross-sectional view showing an overview of a cloud chamber according to the present invention. [Diagram 2] FIG. 1 is a diagram showing a case where a radiation source is inserted into a cloud chamber according to the present invention. [Diagram 3] FIG. 1 is a diagram showing a case where ethanol liquid is circulated in a cloud chamber according to the present invention. [Figure 4] FIG. 13 is a diagram showing a case where circulation is performed using a pump utilizing capillary action in the cloud chamber of the present invention. [Diagram 5] 1 is a photograph showing a cloud chamber according to the present invention. [Figure 6] 1 is a graph showing the change in cooling temperature of a cloud chamber according to the present invention and a photograph showing the tracks of observed natural radiation. [Figure 7] FIG. 1 is a diagram showing a cooling plate for increasing the efficiency of the refrigerator of the cloud chamber according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that components having the same functions are designated by the same reference numerals, and repeated description thereof may be omitted. EXAMPLES

[0020] First, the cloud chamber of the present invention will be described. Fig. 1 is a cross-sectional view showing an outline of the cloud chamber. Fig. 2 is a diagram showing a case where a radiation source is inserted into the cloud chamber. Fig. 3 is a diagram showing a case where ethanol liquid is circulated in the cloud chamber. Fig. 4 is a diagram showing a case where a pump utilizing capillary action is used to circulate in the cloud chamber.

[0021] As shown in FIG. 1, the cloud chamber 100 is used to observe the tracks of radiation passing through a supersaturated vapor layer 310 of ethanol, and contains within a housing 110 an observation box 200 covered with a thermal insulator 210, a refrigerator 120, a heater controller 130, a power supply 140, and a high-voltage power supply 150.

[0022] The observation box 200 is a hollow rectangular container, and is covered with a lid having a transparent observation window on the top so that it can be seen from above. The observation box 200 has a steam generating means for evaporating the ethanol placed inside to form a supersaturated vapor layer 310, a heating glass 220 provided in the observation window to heat the upper part inside the observation box 200, a cooling plate 230 arranged to cool the lower part inside the observation box 200 to create a temperature gradient, an illumination lamp 260 for shining light on the droplets generated by the passage of radiation, and the like.

[0023] The vapor generating means is a tray 240 arranged around the upper inner wall of the observation box 200, with a heater 250 arranged below it. The tray 240 has an open top like a rain gutter and can be filled with liquid. Volatile ethanol is used as the liquid, but alcohols with low vaporization temperatures such as ethylene glycol may also be used. A sponge or fibrous evaporation sheet may be laid inside the tray 240 to increase the evaporation area. The heater 250 generates heat at approximately 30 to 40° C. by the heater controller 130, and generates ethanol vapor 300 by heating the liquid in the tray 240.

[0024] The heating glass 220 is heated by the heater controller 130 so that the temperature of the ethanol vapor 300 diffused to the upper part of the observation box 200 becomes about 30 to 40° C., which is a temperature that does not cause condensation on the observation window. Note that the temperature is not raised too high so that the observer does not get burned if he or she comes into contact with it.

[0025] The cooling plate 230 is cooled by the refrigerator 120, and cools the ethanol vapor 300 diffused to the lower part inside the observation box 200 so that the temperature is approximately -50 to -30°C. The heat absorbing part of the refrigerator 120 may be abutted against the center of the lower surface of the cooling plate 230. The observation box 200, including the refrigerator 120, is surrounded by a heat insulating material 210 to suppress the influence of the temperature from the outside. By lowering the temperature of the lower part of the observation box 200, the saturated vapor amount of the ethanol vapor 300 is reduced, but by increasing the amount of vapor and suppressing condensation, a supersaturated vapor layer 310 is formed.

[0026] When external radiation enters the supersaturated vapor layer 310, the area around the radiation is ionized to generate droplets. Since the supersaturated vapor layer 310 expands if the amount of vapor in the supersaturated vapor layer 310 is prevented from decreasing due to the condensation of the ethanol vapor 300, high-voltage wires 160 may be connected to the upper tray 240 and high voltages may be applied above and below using a high-voltage power supply device 150 to move miscellaneous ions that become the nuclei of condensation to the electrodes and remove them.

[0027] The ethanol liquid 320 that has liquefied through condensation and accumulated at the bottom of the observation box 200 is discharged from the recovery port 270. In order to uniformly cool the entire cooling plate 230, a groove or the like may be formed in the cooling plate 230 to guide the ethanol liquid 320 that has accumulated on the upper surface of the cooling plate 230 to the recovery port 270 of the observation box 200 so that it can be discharged from the recovery port 270. By minimizing the liquid thickness on the cooling plate 230, the cooling efficiency of the entire cooling plate 230 is improved.

[0028] The illumination lamp 260 is a light emitting means such as an LED, and irradiates light from the inner wall of the observation box 200 towards the supersaturated vapor layer 310. By shining light on droplets generated along the movement of the radiation, the track of the radiation can be visually observed through the observation window. Since little heat is generated, the effect on the temperature inside the observation box 200 is suppressed. The power supply unit 140 supplies DC or AC power to the refrigerator 120, heater controller 130, illumination lamp 260, etc.

[0029] 2, a radiation source insertion / removal device 400 may be provided to insert a radiation source from outside into the observation box 200. Opening the lid to insert the radiation source is troublesome, and when the lid is opened, ambient air may enter and temporarily disturb the supersaturated vapor layer 310, making it impossible to observe.

[0030] The radiation source insertion / removal device 400 has an insertion tube 410 with a radiation source attachment section 420 at one end and a sealing section 430 at the other end. After attaching a radiation source to the radiation source attachment section 420, the radiation source can be inserted into the insertion tube 410.

[0031] In addition, it is also possible to add, from outside the observation box 200, beitouite, which is a common source of natural radiation, table salt that is high in potassium, kelp root, the wick (mantle) of an alcohol lamp, hot spring deposits that are high in radium, and the like.

[0032] As shown in Fig. 3, a circulation pump 500 may be provided to supply the ethanol liquid 320 discharged from the recovery port 270 of the observation box 200 to the tray 240 of the vapor generating means. This allows for long-term operation without the need to manually replenish ethanol.

[0033] 4, the ethanol liquid 320 discharged from the recovery port 270 of the observation box 200 may be supplied to the tray 240 of the vapor generating means by a capillary pump 510. It becomes possible to suck up the ethanol liquid 320 without using electricity or the like.

[0034] Figure 5 is a photograph showing the cloud chamber. Figure 6(a) is a photograph showing a graph showing the cooling temperature change of the cloud chamber. Figure 6(b) is a photograph showing the tracks of natural radiation observed in the cloud chamber.

[0035] 5, cloud chamber 100 has a portable size, with the internal volume of observation box 200 visible through an observation window containing heat generating glass 220 being, for example, about 22 cm in length, about 22 cm in width, and about 10 cm in height. At this time, the height of supersaturated vapor layer 310 is about 1 to 3 cm.

[0036] A temperature gradient is formed inside the observation box 200 covered with the heat insulating material 210, for example, with the upper part at about 30 to 40° C. and the lower part at about −50 to −30° C. By removing the lid and pouring 200 mL of ethanol into the tray 240, observation is possible for about 8 hours.

[0037] By creating a temperature difference between the top and bottom inside the observation box 200, the amount of saturated vapor at the top and bottom changes, forming a supersaturated vapor layer 310, the volume of which is proportional to the amount of vapor due to diffusion of the ethanol vapor 300. To maintain the same temperature difference, a cooling capacity according to the amount of vapor is required.

[0038] When the vapor pressure in supersaturated vapor layer 310 reaches an ion limit supersaturation level, for example, four times or more the saturated vapor pressure, droplets grow using ions generated by the passage of radiation as nuclei, and the tracks of the radiation become visible when irradiated with light from illumination lamp 260. Note that when the degree of supersaturation is low, the droplets tend to evaporate as the radius of the nuclei increases.

[0039] Refrigerator 120 is a Stirling cycle refrigerator, and cools cooling plate 230 to −50 to −30° C. By increasing the temperature difference by lowering the temperature at the bottom without increasing the temperature at the top inside observation box 200, it is possible to increase the height of supersaturated vapor layer 310.

[0040] The Stirling cycle is a cooling system that utilizes the property of gas that cools when the refrigerant helium gas expands. The internal piston is continuously driven by a linear motor, and the heat absorbing part on one end of the piston is cooled to a low temperature by the adiabatic expansion of the refrigerant gas inside the piston. This system has excellent cooling capacity, is compact and lightweight, can be used regardless of the mounting direction, and is not easily affected by vibrations caused by movement.

[0041] Refrigerator 120 using the Stirling cycle can cool cooling plate 230 down to approximately -80° C., but because the effect of expanding the height of supersaturated vapor layer 310 decreases below -50° C., approximately -50° C. is preferable. By increasing the height of supersaturated vapor layer 310, which can visualize natural radiation, a larger observation volume can be obtained, and more radiation can be visualized three-dimensionally.

[0042] As shown in FIG. 6(a), after starting up the power supply 140 of the cloud chamber 100, it takes about 75 minutes for the refrigerator 120 to cool the edge of the cooling plate 230 to about -40°C, and the center of the cooling plate 230 is cooled to about -80°C.

[0043] As shown in Fig. 6(b), the natural radiation observed in the cloud chamber 100 is mostly alpha rays and beta rays generated when radon gas in the air inside the cloud chamber 100 naturally decays, and by increasing the size of the observation window and the internal volume of the cloud chamber 100, the amount of radon gas increases and the amount of observed radiation also increases. As for the frequency of alpha rays generated in the cloud chamber 100, seven tracks of natural radiation were visualized per 30 seconds.

[0044] 7 is a diagram showing a cooling plate that increases the efficiency of the refrigerator of the cloud chamber. In order to increase the size of the supersaturated vapor layer 310 in the observation chamber 200, the cooling plate 230 disposed at the bottom is cooled to approximately -50 to -30°C.

[0045] 7(a), for example, in the cloud chamber 100a, the center of the cooling plate 230 is protruded downward to form a covering portion 230a so as to cover the heat absorbing portion 120a of the refrigerator 120. When the heat absorbing portion 120a is cylindrical, the cylindrical covering portion 230a is extended from the center of the cooling plate 230 to surround the heat absorbing portion 120a, and then wrapped in the heat insulating material 210.

[0046] 7(b), in the cloud chamber 100b, the center of the cooling plate 230 is recessed to form a covering portion 230b so as to cover the heat absorbing portion 120b of the refrigerator 120. When the heat absorbing portion 120b is disk-shaped, the covering portion 230b may be embedded in the center of the cooling plate 230 to surround the heat absorbing portion 120b, and then the covering portion 230b may be wrapped in the insulating material 210. By providing the cooling plate 230 with a structure that improves the heat absorbing effect of the refrigerator 120, the cooling plate 230 may be cooled efficiently.

[0047] Stirling cycle refrigerator 120 has a structure in which a piston reciprocates inside a cylinder having heat absorption section 120a at one end and heat exhaust section at the other end. Since it is difficult to abut heat absorption section 120a on the entire cooling plate 230, heat absorption section 120a is abutted against the center of cooling plate 230 to prevent differences in the degree of cooling at the four corners.

[0048] According to the present invention, even if the housing is made small so that it can be moved around educational facilities, etc., by increasing the volume of the cloud chamber and thickening the supersaturated vapor layer in the observation chamber with a cooling capacity greater than or equal to that of a Peltier element, it becomes possible to adequately observe the tracks of natural radiation without the need to artificially introduce a radiation source.

[0049] Although the embodiment of the present invention has been described above, the present invention is not limited to these. For example, the wall surface and the heat generating glass constituting the space inside the cloud chamber may be stacked vertically as a unit structure, and the heat generating glass and the cooling plate may be separated in two stages to increase the thickness of the supersaturated vapor layer. [Explanation of symbols]

[0050] 100: Cloud chamber 110: Housing 120: Refrigeration machine 120a: Heat absorption part 120b: Heat absorption part 130: Heater controller 140: Power supply 150: High voltage power supply 160: High-voltage power cable 200: Observation box 210: Insulation material 220: Heat-generating glass 230: Cooling plate 230a: Covering part 230b: Covering part 240: Tray 250: Heater 260: Lighting 270: Collection port 300: Ethanol vapor 310: Supersaturated vapor layer 320: Ethanol solution 400: Source insertion / extraction device 410: Insertion tube 420: Radiation source attachment part 430: Sealing part 500: Circulation pump 510: Capillary pump

Claims

1. A cloud chamber for observing the tracks of radiation passing through a supersaturated vapor layer of ethanol, An observation box with a lid on the top with an observation window, a vapor generating means for evaporating the ethanol contained in the observation box to form a supersaturated vapor layer; a heating glass provided in the observation window for heating an upper portion of the observation box; A cooling plate arranged to cool the lower part of the observation box to create a temperature gradient; a refrigerator having a heat absorbing part in contact with a lower surface of the cooling plate, The center of the cooling plate is protruded downward so as to cover the heat absorbing portion of the refrigerator. A cloud chamber characterized by

2. A cloud chamber for observing the tracks of radiation passing through a supersaturated vapor layer of ethanol, An observation box with a lid on the top with an observation window, a vapor generating means for evaporating the ethanol contained in the observation box to form a supersaturated vapor layer; a heating glass provided in the observation window for heating an upper portion of the observation box; A cooling plate arranged to cool the lower part of the observation box to create a temperature gradient; a refrigerator having a heat absorbing part in contact with a lower surface of the cooling plate, The center of the cooling plate is recessed so as to cover the heat absorbing portion of the refrigerator. A cloud chamber characterized by

3. In order to uniformly cool the entire cooling plate, a groove is formed in the cooling plate so that ethanol accumulated on the upper surface of the cooling plate can be discharged to the collection port of the observation box.

3. A cloud chamber according to claim 1 or 2.

4. a circulation pump is provided to supply the ethanol discharged from the recovery port of the observation box to the vapor generating means; 3. A cloud chamber according to claim 1 or 2.

5. The ethanol discharged from the recovery port of the observation box is supplied to a tray of the vapor generating means by a pump utilizing capillary action.

3. A cloud chamber according to claim 1 or 2.

6. applying a high voltage to the tray of the vapor generating means so as to suppress a decrease in the amount of vapor in the supersaturated vapor layer due to condensation of the ethanol vapor and to expand the supersaturated vapor layer; 3. A cloud chamber according to claim 1 or 2.

7. A radiation source insertion / removal device is provided for inserting a radiation source into the observation box from the outside.

3. A cloud chamber according to claim 1 or 2.

8. The refrigerator is a Stirling cycle refrigerator and cools the cooling plate to −50 to −30° C.

3. A cloud chamber according to claim 1 or 2.

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