JP7385329B1 - cloud chamber - Google Patents

Abstract

[Problem] To provide a portable cloud chamber whose volume is increased and the layer of supersaturated vapor is thickened to make it easier to observe the tracks of natural radiation. [Solution] A cloud chamber for observing the trajectory of radiation passing through a supersaturated vapor layer of ethanol, which includes an observation box whose top surface is covered with a lid with an observation window, and evaporates the ethanol contained in the observation box. a steam generating means for forming a supersaturated vapor layer by heating the observation box; a heat-generating glass provided in the observation window for heating the upper part of the observation box; and a heat generating glass for cooling the lower part of the observation box to create a temperature gradient. and a refrigerator having a heat absorption part in contact with a lower surface of the cooling plate, the center of the cooling plate protruding downward so as to cover the heat absorption part of the refrigerator, It is characterized by [Selection diagram] Figure 1

Description

The present invention relates to a portable cloud chamber that has an increased capacity and a thicker layer of supersaturated vapor to make it easier to observe the tracks of natural radiation.

A cloud chamber is a device that uses the condensation effect of steam to visualize the tracks of charged particles. A liquid such as alcohol is heated and evaporated in the upper part of the cloud chamber, and a supersaturated vapor layer is generated by cooling the lower part of the cloud chamber and creating a temperature gradient. When radiation enters there, the gas is ionized and droplets are generated, so the trajectory of the radiation can be observed by shining light on it.

Cloud chambers are installed as teaching materials in, for example, science museums and educational facilities. The radiation that a cloud chamber attempts to observe 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 can be increased and observed. There will also be more radiation.

Additionally, if the observation window of the cloud chamber is small, the walls of the cloud chamber will block alpha rays from outside, reducing the amount of observation. If you try to make the observation window larger, you will need to increase the cooling capacity according to the area, and if you use a refrigerator that uses refrigerant gas circulation, the entire cloud chamber will become larger. It becomes difficult.

As described in Patent Document 1, an invention of a cloud chamber is also disclosed in which the temperature of the device is lowered so that even if an observer comes into contact with it, it will not cause burns or the like and it will be easier to see the tracks of charged particles inside the container. ing. Furthermore, as described in Patent Document 2, an electronic cooling element that cools the inside of the observation tank keeps the temperature difference between the upper and lower surfaces of the observation tank at an optimal value, making it easy to observe many natural radiation tracks, making it lightweight and compact. The invention of a low-temperature diffusion type cloud chamber is also disclosed.

Japanese Patent Application Publication No. 09-184887 Patent No. 4537332

Although it is possible to reduce the size and weight by using a Peltier element as in Patent Document 1 and Patent Document 2, it is difficult to obtain sufficient cooling capacity for a large observation window. If the observation window is small, the amount of radon gas it contains will be small, making it difficult to observe radiation.Therefore, radon gas is sometimes artificially injected into the cloud chamber to generate tracks, but this does not allow for natural radon gas to be generated. It is unreasonable to say that we are observing radiation that exists.

SUMMARY OF THE INVENTION 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, thereby making it easier to observe the tracks of natural radiation.

In order to solve the above problems, the present invention provides a cloud chamber for observing the trajectory of radiation passing through a supersaturated vapor layer of ethanol, the observation box having an upper surface covered with a lid having an observation window; a steam generating means for evaporating ethanol placed in the observation box to form a supersaturated vapor layer; a heat generating glass provided in the observation window for warming the upper part of the observation box; and a lower part of the observation box. a cooling plate disposed to create a temperature gradient by cooling the refrigerator; and a refrigerator having a heat absorption part in contact with a lower surface of the cooling plate, the cooling plate being arranged to cover the heat absorption part of the refrigerator. It is characterized by having the center protrude downward.

The present invention also provides a cloud chamber for observing the trajectory of radiation passing through a supersaturated vapor layer of ethanol, which includes an observation box whose top surface is covered with a lid having an observation window, and an ethanol chamber placed in the observation box. a steam generating means for evaporating to form a supersaturated vapor layer; a heat-generating glass provided in the observation window to warm the upper part of the observation box; and a temperature gradient by cooling the lower part of the observation box. and a refrigerator having a heat absorption part in contact with a lower surface of the cooling plate, the center of the cooling plate being depressed so as to cover the heat absorption part of the refrigerator, It is characterized by

In the cloud chamber, in order to uniformly cool the entire cooling plate, grooves are formed in the cooling plate so that ethanol accumulated on the upper surface of the cooling plate is discharged to a collection port of the observation box. It is characterized by

The cloud chamber is characterized in that a circulation pump is provided for supplying the ethanol discharged from the collection port of the observation box to the steam generation means.

The cloud chamber is characterized in that the ethanol discharged from the collection port of the observation box is supplied to the tray of the steam generation means by a pump that utilizes capillary action.

In the cloud chamber, a high voltage is applied to the tray of the steam generation means so as to suppress a decrease in the amount of steam in the supersaturated vapor layer due to condensation of ethanol vapor and to spread the supersaturated vapor layer.
It is characterized by

The cloud chamber is characterized in that it includes a radiation source insertion/extraction device for inserting a radiation source into the observation chamber from the outside.

In the cloud chamber, the refrigerator is a Stirling cycle refrigerator, and the cooling plate is cooled to -50 to -30°C.

According to the present invention, even if the casing is made smaller so that it can be used around educational facilities, the volume of the cloud chamber is increased, and the supersaturated vapor layer inside the observation chamber is thickened with a cooling capacity greater than that of a Peltier device. It will be possible to sufficiently observe the tracks of natural radiation without introducing a radioactive source.

1 is a sectional view showing an outline of a cloud chamber according to the present invention. FIG. 2 is a diagram showing a case where a radiation source is introduced into the cloud chamber according to the present invention. It is a figure showing the case where ethanol liquid is circulated in the cloud chamber which is the present invention. FIG. 3 is a diagram illustrating a case where a pump that utilizes capillary phenomenon is used to circulate in the cloud chamber of the present invention. It is a photograph showing the cloud chamber of the present invention. 2 is a graph showing changes in the cooling temperature of the cloud chamber according to the present invention, and a photograph showing the trajectory of observed natural radiation. FIG. 2 is a diagram showing a cooling plate that increases the efficiency of the cloud chamber refrigerator according to the present invention.

Embodiments of the present invention will be described in detail below with reference to the drawings. Components having the same functions are designated by the same reference numerals, and repeated explanations may be omitted.

First, the cloud chamber of the present invention will be explained. FIG. 1 is a sectional view showing an outline of a cloud chamber. FIG. 2 is a diagram showing a case where a radiation source is introduced into a cloud chamber. FIG. 3 is a diagram showing a case where ethanol liquid is circulated in a cloud chamber. FIG. 4 is a diagram showing a case where a pump utilizing capillary phenomenon is used to circulate in a cloud chamber.

As shown in FIG. 1, the cloud chamber 100 is for observing the trajectory of radiation passing through a supersaturated vapor layer 310 of ethanol, and is housed in a housing 110 surrounded by a heat insulating material 210. A box 200, a refrigerator 120, a heater controller 130, a power supply device 140, a high voltage power supply device 150, and the like are accommodated.

The observation box 200 is a rectangular container with a hollow interior, and is covered with a lid having a transparent observation window on the upper surface so as to be visible from above. The observation box 200 includes a steam generating means for evaporating the ethanol contained therein to form a supersaturated vapor layer 310, a heat generating glass 220 provided in the observation window to warm the upper part of the inside of the observation box 200, and a heating glass 220 inside the observation box 200. It has a cooling plate 230 disposed to cool the lower part of the liquid to create a temperature gradient, an illumination lamp 260 for shining light on droplets generated by the passage of radiation, and the like.

As the steam generating means, a tray 240 is arranged so as to go around the upper inner wall of the observation box 200, and a heater 250 is arranged below the tray 240. The tray 240 has an open top surface like a rain gutter and can contain liquid. As the liquid, volatile ethanol is used, but alcohols with a low vaporization temperature such as ethylene glycol may also be used. A sponge or fibrous evaporation sheet may be placed inside the tray 240 to increase the evaporation area. The heater 250 generates heat at about 30 to 40° C. by the heater controller 130, and generates ethanol vapor 300 by heating the liquid in the tray 240.

The heating glass 220 is heated by the heater controller 130 so that the temperature of the ethanol vapor 300 diffused in the upper part of the observation box 200 is about 30 to 40° C., which is enough to prevent condensation on the observation window. In addition, be careful not to raise the temperature too much so that observers will not get burns if they come into contact with it.

The cooling plate 230 is cooled by the refrigerator 120 so that the temperature of the ethanol vapor 300 diffused in the lower part of the observation box 200 is about -50 to -30°C. Note that the heat absorbing portion of the refrigerator 120 may be brought into contact with the center of the lower surface of the cooling plate 230. Surrounding the observation box 200 including the refrigerator 120 with a heat insulating material 210 suppresses external influences on the temperature. Although the saturated vapor amount of the ethanol vapor 300 is reduced by lowering the temperature at the bottom of the observation box 200, a supersaturated vapor layer 310 is formed by increasing the vapor amount and suppressing condensation.

When radiation enters the supersaturated vapor layer 310 from the outside, the area around the radiation is ionized and droplets are generated. If the amount of vapor in the supersaturated vapor layer 310 is suppressed from decreasing due to condensation of the ethanol vapor 300, the supersaturated vapor layer 310 will expand. By applying a high voltage, miscellaneous ions that become condensation nuclei may be moved to the electrode and removed.

The ethanol liquid 320 that has been liquefied by 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, grooves or the like are formed in the cooling plate 230 leading to the collection port 270 so that the ethanol liquid 320 accumulated on the top surface of the cooling plate 230 is discharged from the collection port 270 of the observation box 200. It may be formed. By minimizing the liquid thickness on the cooling plate 230, the overall cooling efficiency of the cooling plate 230 is improved.

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 toward the supersaturated vapor layer 310. By shining light on the droplets generated along the movement of the radiation, the trajectory of the radiation can be seen through the observation window. Since less heat is generated, the influence on the temperature inside the observation box 200 can be suppressed. Note that the power supply device 140 supplies DC or AC power to the refrigerator 120, the heater controller 130, the lighting lamp 260, and the like.

As shown in FIG. 2, a radiation source insertion/extraction device 400 for inserting a radiation source into the observation box 200 from the outside may be provided. Opening the lid to insert the radiation source is time-consuming, and when the lid is opened, ambient air gets mixed in and temporarily disturbs the supersaturated vapor layer 310, making it impossible to observe it.

In the radiation source insertion/extraction device 400, one end of the insertion tube 410 is a radiation source attachment part 420, and the other end is a sealing part 430. It is sufficient to attach a radiation source to the radiation source attachment part 420 and then insert the radiation source into the insertion tube 410.

In addition, from outside the observation box 200, objects such as northern tolite, which is a daily source of natural radiation, table salt that contains a lot of potassium, root kelp, alcohol lamp wick (mantle), and hot water flower that contains a lot of radium can be introduced. good.

As shown in FIG. 3, a circulation pump 500 may be provided for supplying the ethanol liquid 320 discharged from the collection port 270 of the observation box 200 to the tray 240 of the steam generation means. Long-term operation is possible without artificially replenishing ethanol.

Further, as shown in FIG. 4, the ethanol liquid 320 discharged from the collection port 270 of the observation box 200 may be supplied to the tray 240 of the steam generation means by the capillary pump 510. It becomes possible to suck up the ethanol liquid 320 without using electricity or the like.

FIG. 5 is a photograph showing the cloud chamber. FIG. 6(a) is a photograph showing a graph showing changes in the cooling temperature of the cloud chamber. FIG. 6(b) is a photograph showing the trajectory of natural radiation observed with a cloud chamber.

As shown in FIG. 5, the volume of the cloud chamber 100 inside the observation box 200 that can be confirmed from the observation window containing the heat generating glass 220 is, for example, about 22 cm in length, about 22 cm in width, and about 10 cm in height. It is a portable size. At this time, the height of the supersaturated vapor layer 310 is about 1 to 3 cm.

The temperature inside the observation box 200 covered with the heat insulating material 210 forms a temperature gradient, for example, about 30 to 40° C. at the top and about -50 to -30° C. at the bottom. By removing the lid and injecting 200 mL of ethanol into the tray 240, observation is possible for about 8 hours.

By providing a temperature difference between the upper and lower sides in the observation box 200, the amount of saturated vapor in the upper and lower portions changes and a supersaturated vapor layer 310 is formed, but the volume of the supersaturated vapor layer 310 is proportional to the amount of vapor caused by diffusion of the ethanol vapor 300. In order to maintain the same temperature difference, a cooling capacity corresponding to the amount of steam is required.

When the vapor pressure in the supersaturated vapor layer 310 reaches an ion limit supersaturation degree that is, for example, four times or more the saturated vapor pressure, droplets grow with ions generated by the passage of radiation as nuclei, so it is not necessary to apply light from the illumination lamp 260. The trajectory of the radiation becomes visible. Note that when the degree of supersaturation is low, droplets tend to evaporate as the radius of the nucleus increases.

Refrigerator 120 is a Stirling cycle refrigerator and cools cooling plate 230 to -50 to -30°C. The height of the supersaturated vapor layer 310 can be increased by lowering the lower temperature of the observation box 200 without increasing the upper temperature to increase the temperature difference.

The Stirling cycle is a cooling system that takes advantage of the gas properties of helium gas, which cools down when it is expanded. 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 adiabatic expansion of the refrigerant gas inside the piston.It has excellent cooling capacity, is small and lightweight, and is installed It can be used in any direction and is not easily affected by vibrations caused by movement.

The refrigerator 120 using the Stirling cycle is capable of cooling the cooling plate 230 to about -80°C, but when the temperature drops below -50°C, the effect of increasing the height of the supersaturated vapor layer 310 becomes small, so the cooling plate 230 can cool down to about -50°C. is preferred. By increasing the height of the supersaturated vapor layer 310 that can visualize natural radiation, a larger observation volume can be obtained and more radiation can be visualized three-dimensionally.

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

As shown in FIG. 6(b), the natural radiation observed in the cloud chamber 100 consists mostly of alpha rays and beta rays, which are generated when radon gas in the air inside the cloud chamber 100 naturally decays. By increasing the volume of the cloud chamber 100, the amount of radon gas increases and the amount of radiation observed also increases. As for the frequency of occurrence of alpha rays in the cloud chamber 100, seven natural radiation tracks were visualized every 30 seconds.

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

As shown in FIG. 7A, for example, in the cloud chamber 100a, the center of the cooling plate 230 is made to protrude downward to form a covering part 230a so as to cover the heat absorption part 120a of the refrigerator 120. When the heat absorbing portion 120a is cylindrical, a cylindrical covering portion 230a may be extended from the center of the cooling plate 230 to surround the heat absorbing portion 120a, and then wrapped with the heat insulating material 210.

Further, as shown in FIG. 7B, in the cloud chamber 100b, the center of the cooling plate 230 is depressed to form a covering part 230b so as to cover the heat absorption part 120b of the refrigerator 120. When the heat absorbing portion 120b is disk-shaped, the heat absorbing portion 120b may be surrounded by the covering portion 230b so as to be embedded in the center of the cooling plate 230, and then wrapped with the heat insulating material 210. By configuring the cooling plate 230 to have a structure that improves the heat absorption effect of the refrigerator 120, the cooling plate 230 can be efficiently cooled.

The Stirling cycle refrigerator 120 has a structure in which a piston reciprocates inside a cylinder with a heat absorption section 120a at one end and a heat exhaust section at the other end, and it is difficult to bring the heat absorption section 120a into contact with the entire cooling plate 230. Therefore, the heat absorbing portion 120a is brought into contact with the center of the cooling plate 230, so that there is no difference in the degree of cooling at the four corners.

According to the present invention, even if the casing is made smaller so that it can be used around educational facilities, the volume of the cloud chamber is increased, and the supersaturated vapor layer inside the observation chamber is thickened with a cooling capacity greater than that of a Peltier device. It will be possible to sufficiently observe the tracks of natural radiation without introducing a radioactive source.

Although the embodiments of the present invention have been described above, the present invention is not limited thereto. For example, the walls that make up the space inside the cloud chamber and the heat-generating glass can be stacked vertically as a unit structure, and the thickness of the supersaturated vapor layer can be increased by stacking them in two layers to separate the heat-generating glass and the cooling plate. You can do it like this.

100: Cloud chamber 110: Housing 120: Freezer 120a: Heat absorption part 120b: Heat absorption part 130: Heater controller 140: Power supply device 150: High voltage power supply device 160: High voltage electric wire 200: Observation box 210: Heat insulating material 220: Heat generating glass 230: Cooling plate 230a: Covering section 230b: Covering section 240: Tray 250: Heater 260: Lighting lamp 270: Recovery port 300: Ethanol vapor 310: Supersaturated vapor layer 320: Ethanol liquid 400: Source insertion/extraction device 410: Insertion tube 420 : Source attachment part 430: Sealing part 500: Circulation pump 510: Capillary pump

Claims (7)

A cloud chamber for observing the trajectory of radiation passing through a supersaturated vapor layer of ethanol,
An observation box whose top surface is covered with a lid with an observation window,
a steam generating means for evaporating the ethanol placed in the observation box to form a supersaturated vapor layer;
a heat-generating glass provided in the observation window to warm the upper part of the observation box;
a cooling plate arranged to cool the lower part of the observation box to create a temperature gradient;
a refrigerator in which a heat absorbing part is brought into contact with the bottom surface of the cooling plate where liquefied ethanol accumulates, instead of the top surface,
The refrigerator has a cylindrical body with a heat absorbing part at one end and a heat exhausting part at the other end, and the cylindrical heat absorbing part is surrounded by a covering part that projects downward from the center of the cooling plate. The covering portion is wrapped with a heat insulating material,
In order to uniformly cool the entire cooling plate, grooves are formed in the cooling plate so that the ethanol accumulated on the upper surface of the cooling plate is discharged to the collection port of the observation box.
A cloud chamber characterized by: A cloud chamber for observing the trajectory of radiation passing through a supersaturated vapor layer of ethanol,
An observation box whose top surface is covered with a lid with an observation window,
a steam generating means for evaporating the ethanol placed in the observation box to form a supersaturated vapor layer;
a heat-generating glass provided in the observation window to warm the upper part of the observation box;
a cooling plate arranged to cool the lower part of the observation box to create a temperature gradient;
a refrigerator in which a heat absorbing part is brought into contact with the bottom surface of the cooling plate where liquefied ethanol accumulates, instead of the top surface,
The refrigerator has a cylindrical body with a heat absorbing part on one end and a heat exhausting part on the other end, and the cooling plate is surrounded by a disc-shaped heat absorbing part with a concave covering part in the center, and then the covering part is part is wrapped in insulation material,
In order to uniformly cool the entire cooling plate, grooves are formed in the cooling plate so that the ethanol accumulated on the upper surface of the cooling plate is discharged to the collection port of the observation box.
A cloud chamber characterized by: providing a circulation pump that supplies the ethanol discharged from the collection port of the observation box to the steam generation means;
The cloud chamber according to claim 1 or 2, characterized in that: supplying the ethanol discharged from the collection port of the observation box to the tray of the steam generation means by a pump that utilizes capillary action;
The cloud chamber according to claim 1 or 2, characterized in that: Applying a high voltage to the tray of the steam generating means so as to suppress a decrease in the amount of vapor in the supersaturated vapor layer due to condensation of ethanol vapor and to spread the supersaturated vapor layer;
The cloud chamber according to claim 1 or 2, characterized in that: comprising a radiation source insertion/extraction device for inserting a radiation source into the observation box from the outside;
The cloud chamber according to claim 1 or 2, characterized in that: The refrigerator is a Stirling cycle refrigerator, and cools the cooling plate to -50 to -30°C.
The cloud chamber according to claim 1 or 2, characterized in that: