JPH09184887A - Cloud chamber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily observe the track of charged particles inside a vessel without suffering a burn even with a contact of an observer by lowering the temperature in the device. SOLUTION: A cloud chamber has a transparent glass-made side wall part 11 and a bottom part 14 and is provided with a vessel 10 of which the upper part is opened, an upper lid 40 to cover and close the vessel 10 and seal the inside, make the inside of the vessel, capable of seeing through and equip with a heating means, an annular member 20 arranged along the inner surface of the side wall part 11 of the vessel 10 and forming a heater in one, and a wettable cloth part 30 of cotton thread including liquid which is contained in a bump part 21 in the annular member 20. For a cooling means to cool the bottom of the vessel 10 and cool the liquid vapor evaporated in the vessel to condense, Peltier elements 50 are utilized. For transparent heating glass 43 constituting the upper lid 40, a glass plate evaporated by nichrome thin film is used so as not to shield the view and to make the inside of the vessel 10 visible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fog chamber used for observing tracks of charged particles, and more particularly to a fog chamber having a structure capable of lowering the temperature and being easy to use.

[0002]

2. Description of the Related Art A fog chamber is a device for observing tracks of charged particles by forming a fog in a gas. Especially, since the track of radiation can be observed, it is suitable for students, students, or radiation workers to acquire basic knowledge of radiation properties and radiation management, for example, for educational training. It is used as a teaching material.

Such a conventional fog chamber is, for example, an actual flatbed 7
As is known from Japanese Patent Publication No. 29490, etc., the upper surface of a cylindrical glass container is closed by an upper lid portion.
The upper lid portion is made of a transparent glass plate with a heater incorporated therein so that the inside of the container can be seen through. Then, an impregnating member impregnated with ethylene glycol is attached to the upper part of the container along the inner peripheral surface of the side wall of the container, and the impregnating member is indirectly applied from the outside of the container or directly from the inside of the container. And the liquid such as ethylene glycol impregnated in the impregnating member is vaporized. On the other hand, a cooling fan is provided on the bottom side of the cylindrical glass container to liquefy and vaporize vapor such as ethylene glycol existing near the bottom of the container. Further, a temperature detecting element such as a thermostat for detecting the temperature of each part in the container is provided, and the temperature detected by these temperature detecting elements controls the heating temperature of the heater of the upper lid and the impregnating member.

In such a conventional mist box, when the impregnating member is heated on the upper side of the container, the ethylene glycol impregnated therein is vaporized, and mist of ethylene glycol is generated in the container. On the other hand, when a mist of ethylene glycol existing near the bottom of the container is cooled and condensed on the lower side of the container by a cooling fan, a liquid of ethylene glycol is produced. In this way, a supersaturated vapor layer of ethylene glycol is formed in the container. When charged particles such as radiation pass through the supersaturated vapor layer of ethylene glycol in the container in this state, positive and negative ions are generated along the tracks, and mist droplets are formed by using the positive and negative ions as nuclei. Therefore, the track of the charged particles can be observed by illuminating the side surface.

In the conventional fog chamber, a heating vapor layer is formed immediately below the observation window by heating with a heater provided on the upper lid, and a saturated vapor layer is formed in the horizontal direction of the impregnation member by heating the heater of the impregnation member. It Therefore, by forming a supersaturated vapor layer, which is an effective region, in the container space between the saturated vapor layer and the condensed liquid surface, the temperature gradient becomes constant and stable, and droplets are less likely to occur in the observation window. ing.

[0006]

In the conventional fog box,
In order to form a heating vapor layer near the upper lid of the space inside the container, a heater is incorporated in the glass plate forming the upper lid. Further, a heater for heating the impregnating member is provided in order to vaporize the ethylene glycol impregnated in the impregnating member to form a saturated vapor layer. Then, when heating with these heaters, in order to obtain stable operation without generating droplets in the observation window, the temperature difference between the heating vapor layer and the condensate surface is calculated based on the experimentally confirmed experience. Almost 105-11
Keep the temperature at 0 ° C and keep the impregnated member at about 10-20
It will be kept at a low temperature.

In the conventional fog chamber for cooling and condensing the fog existing in the vicinity of the bottom of the container by the cooling fan,
Especially when ethylene glycol is used, the cooling capacity at the bottom of the container is not always sufficient. Therefore, in order to satisfy the above conditions and obtain a stable operation, it is necessary to raise the temperatures of the heater of the upper lid portion and the heater of the impregnating member to a considerably high temperature. However, when the upper part of the container is heated to a high temperature in this way, when it is used as a teaching material at school,
Students may get burned. Further, since a heater such as a nichrome wire is incorporated in the glass plate, the linear heater is present in front of the portion where the tracks of charged particles appear inside the container. Therefore, there is a problem in that this heater is an obstacle to focusing the eyes and is extremely difficult to see.

Therefore, in view of the above problems in the conventional fog chamber, it is an object of the present invention to obtain a fog chamber which can lower the temperature of the device and is therefore safe and suitable for use as a teaching material. Another object of the present invention is to provide a fog box which is not obstructed by the heater provided on the upper lid part and which makes it easy to see the tracks of charged particles generated inside the container and makes it easy to observe the tracks.

[0009]

In the present invention, in order to achieve the above-mentioned object, by using a Peltier element as a cooling means provided in the lower part of the container for cooling and condensing the vapor of the vaporized liquid, As a liquid to be vaporized in the container, ethanol or methanol having a lower vaporization temperature than ethylene glycol can be used.
Further, the heating means provided on the upper lid portion is a thin metal film formed on the surface of the upper lid portion and having a thinness that does not lose the transparency of the upper lid portion. This prevents the track of charged particles generated inside the container from becoming difficult to see.

That is, the fog chamber according to the present invention has a container having a transparent side wall and a bottom and having an open upper surface, a transparent upper lid portion for sealingly covering the upper surface of the container, and a transparent lid provided on the upper lid portion. A heating means for heating the upper part of the internal space of the container, an impregnating member for impregnating the liquid provided on the upper part of the container along the inner peripheral surface of the side wall of the container, and heating the impregnating member, An impregnating member heating means for vaporizing the impregnated liquid and a cooling means provided at a lower portion of the container for cooling and condensing vapor of the vaporized liquid are used, and a Peltier element is used as the cooling means. It is what

Further, in such a mist chamber, a liquid having a lower vaporization temperature than ethylene glycol is used as the liquid. Further, the heating means provided on the upper lid portion is formed on the surface of the upper lid portion and is made of a thin metal thin film that does not lose the transparency of the upper lid portion.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a side sectional view of the essential parts of an example of a fog chamber according to the invention. In this figure, reference numeral 10 indicates a container of a mist box. The container 10 has a cylindrical side wall portion 11 made of glass which is a transparent member, and a brim shape made of, for example, a metal connected to the lower end of the side wall portion 11. Member 12 and the bottom portion 14 made of, for example, a metal plate member to which the flange member 12 is attached by screws 13, 13. That is,
This container 10 is a container whose bottom is closed and whose upper surface is open.

At the upper end of the cylindrical side wall 11 made of glass, an annular member 2 made of, for example, metal, having a diameter substantially the same as that of the cylindrical side wall 11.
0 is listed. The annular member 20 has a recess 21 having a substantially U-shaped cross section and extending inward. The concave portion 21 of the annular member 20 is the side wall portion 1 of the container 10.
1 is arranged along the inner peripheral surface. Inside the recess 21, an impregnation member 30 made of, for example, black cotton thread and impregnated with a liquid, which will be described later, is stored, and the recess 21 has recesses 22 and 22 facing downward at equal intervals. It is provided. Through the recesses 22 and 22, the hanging parts 31 and 31 made of a cotton thread that are continuous with the impregnating member 30 hang downward with a length reaching the bottom of the container 10. By the hanging parts 31, 31 of the cotton thread, the liquid accumulated at the bottom of the container 10 is sucked up by the capillary phenomenon, and the recess 21 is formed.
Is pumped up to the impregnation member 30 housed inside. Although not shown, the annular member 20 is integrally formed with a heating element. By supplying electric power to the heating element, the impregnating member 30 made of cotton thread can be directly heated. ing.

Further, the cylindrical side wall portion 1 made of glass is used.
Above the annular member 20 placed on the upper end of the container 1, there is provided a transparent upper lid portion 40 that covers the upper surface of the container to seal the internal space of the container 10. This upper lid 40
Is an annular frame body 4 having two stepped portions formed on the inner peripheral side thereof.
1, a disc-shaped heat generating glass 43 fitted in the first step portion 42 of the frame 41, and a disc-shaped protective glass 45 fitted in the second step portion 44. .

A metal thin film of nichrome or the like is formed on the outer surface (upper surface in the drawing) of the disc-shaped heat-generating glass 43 fitted in the first step portion 42 by means such as vacuum deposition. The metal thin film is formed to a thickness such that the transparency of the upper lid 40 is not lost. By supplying power to the metal thin film such as nichrome, heat can be generated, and the inside of the container 10 can be observed through the transparent upper lid portion 40 without being blocked by the metal thin film. The inside of the container 10 is observed from the outside of the transparent protective glass 45 provided outside the transparent heating glass 43. In the figure, reference numeral 46 is a gasket which is arranged between the annular member 20 and the upper lid portion 30 and hermetically seals the gap therebetween.
Is made of annular rubber.

The bottom portion 14 of the container 10, more specifically, the outer surface (the lower surface in the figure) of the metal plate member forming the bottom portion 14 has an electron as a lower heating and cooling source (cooling means). Cooling elements, so-called Peltier elements 50, 5
0 is arranged. These Peltier elements 50, 50
A cooling plate 60 having a plurality of fins projecting downward is tightly fixed to the lower side via the screws 13 and 13, and a plurality of the fins 61 and 6 projecting downward are provided below the cooling plate 60.
A plurality of heat radiating fans 70, 70 for supplying cooling air to 1 from below are provided.

Reference numerals 80 and 80 in the figure are illumination lamps for observing the tracks of charged particles including radiation in the inner space of the container by illuminating the cylindrical side wall portion 11 of the container 10 from its side surface. And reference numeral 81
Is a fixing plate that forms a part of a casing that is arranged so as to surround the periphery of the container 10 in order to fix the illumination lamps 80, 80 to the periphery of the container 10.

According to the mist chamber of the present invention having such a structure, it is arranged at the bottom portion 14 of the container 10 and serves as a cooling means for cooling and condensing vapor of the vaporized liquid in the vicinity of the bottom surface of the container. By using the Peltier element, the cooling time can be shortened, that is, the temperature responsiveness can be significantly improved, as compared with the conventional technique in which the cooling fan is simply arranged as described above. As a result, even when alcohol having a lower vaporization temperature than ethylene glycol is used as the fog raw material, the condensation temperature can be accurately controlled. Therefore, the temperature of the heater of the upper lid portion 40 and the heater of the impregnating member 30, that is, the temperature of the transparent heating glass 43 and the annular member 20 that directly heats the impregnating member 30 is not increased too much, and the condensation with the heating vapor layer is achieved. It is possible to keep the temperature difference with the liquid surface at a desired temperature difference. Therefore, the temperature of the fog chamber device can be lowered, and there is no fear of a burn when an observer comes into contact with the device, and the device can be safely used even when used as a teaching material at a school or the like.

Further, not only the above-mentioned ethylene glycol but also alcohols such as ethanol and methanol having a lower vaporization temperature than ethylene glycol can be used as the raw material of the mist. Such an alcohol having a lower vaporization temperature than ethylene glycol is used in the container 10.
When used as a liquid that vaporizes inside, the temperatures of the heater of the upper lid portion 40 and the heater of the impregnating member 30, that is, the temperatures of the transparent heating glass 43 and the annular member 20 that directly heats the impregnating member 30 are compared with the conventional one. When used as a teaching material for a school, there is no need to worry that the student, who is an observer, will get burned, and the fog box can be used as a safe teaching material.

Further, among the glasses forming the upper lid portion 30, as the heat generating glass 43 arranged below the protective glass 45 forming the viewing window for the observer to see, heat generating glass in which a thin nichrome thin film is vacuum-deposited is used. As a result, there is no annoyance such as the fact that the field of view is blocked by the heater as in the conventional case. That is, the track of the charged particles generated inside the container 10 is not obstructed to focus on the inside of the container 10, and the track of the particles can be easily seen.

Although not described above, in the fog box of the present invention, the container 10 is also used as in the prior art.
A temperature sensor is provided in the internal space of the, and the position of the impregnating member 30 and the like arranged in the recess 21 of the annular member 20. Then, by controlling the electric power supplied to the heating means in accordance with the temperature detected by these sensors, the vapor generation amount of the liquid from the impregnating member is kept constant, and the superheated vapor layer is introduced into the container 10 from above. , The saturated vapor layer, the effective region of the supersaturated vapor layer and the condensed liquid surface of the liquid are easily and stably maintained. As a result, the tracks of the charged particles can be stably observed in the effective region (supersaturated vapor layer) where the tracks of the charged particles are formed.

[0022]

As is clear from the above description, in the fog chamber according to the present invention, the temperature inside the container can be lowered, so that the temperature of the upper lid and the like can be suppressed to a low level, which is Eliminates the worry of burns when touching the device,
You get a safe fog box. This becomes more remarkable when alcohol having a low vaporization temperature is used as a raw material for the mist.

Furthermore, by using the heat-generating glass coated with the nichrome thin film, the linear heater makes it possible to obtain a fog box which is easy to observe without any trouble such as difficulty in observing the inside of the container. As a result, cosmic rays (μ, π particles, etc.),
Tracks of charged particles such as α, β, γ rays (recoil electrons) and neutron rays (recoil protons) can be easily observed, and it becomes easy to understand the interaction between charged particles and a substance.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a main part of a fog box according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Container 11 Side wall part 14 Bottom part 20 Annular member 21 Recessed part 30 Cotton thread impregnation member 31 Cotton thread descent part 40 Upper lid part 41 Frame body 43 Heat generating glass 45 Protective glass 50 Peltier element 60 Cooling plate 61 Fin 70 Radiating fan 80 Lighting Lamp

Claims (3)

[Claims] 1. A container having a transparent side wall portion and a bottom portion, the upper surface of which is open, a transparent upper lid portion which covers the upper surface of the container in a sealed state, and a transparent lid provided on the upper lid portion, Heating means for heating the upper part, an impregnating member for impregnating the liquid provided on the upper part of the container along the inner peripheral surface of the side wall of the container, and the impregnating member is heated to vaporize the liquid impregnated therein. A fog box provided with an impregnating member heating means and a cooling means provided at a lower portion of the container for cooling and condensing vaporized liquid vapor, wherein a Peltier element is used as the cooling means. . 2. The fog chamber according to claim 1, wherein the liquid having a lower vaporization temperature than ethylene glycol is used as the liquid. 3. The fog box according to claim 1 or 2, wherein the heating means provided on the upper lid is formed on the surface of the upper lid and is thin enough not to lose the transparency of the upper lid. A fog chamber characterized by being made of a metal thin film of.