JPH11248844A - Low temperature diffusion cloud chamber and jig for use in observation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low temperature diffusion cloud chamber which is easy in temperature control and enables easy observation of a track of a particle rays, etc. SOLUTION: Outputs of an electronic cooling element 12 for cooling the bottom face part 11a of an observation bath 11 in which ethanol is sealed and an electric heater 15 set at an upper part of the observation bath 11 are controlled by a control device 19, thereby properly maintaining a temperature difference of the ethanol gas at the upper part and bottom part of the observation bath. A supersaturated layer A is accordingly easily obtained. When a cap for controlling a count and a direction of charged particles emitted to a charged particle source is mounted, a track of each particle can be observed more easily.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-temperature diffusion type fog box and an observation jig used in a physical experiment or the like of a school.

[0002]

2. Description of the Related Art FIG. 6 is a conceptual view of a conventional low-temperature diffusion type fog box, and shows a cross section thereof. In the low-temperature diffusion type fog box, after filling the inside of the observation tank 1 with ethanol gas (for example, putting ethanol into the observation tank and evaporating it), the bottom surface 1a of the observation tank 1 is dried with a cooling agent. Cool with ice 2. Note that liquid nitrogen or the like is also used as a coolant. When the bottom surface 1a is cooled in this manner, the ethanol gas in the observation tank 1 has a temperature gradient in the vertical direction in the figure, and a supersaturated layer A as shown in the figure is formed. At this time,
The difference ΔT between the temperature of the bottom part 1a and the temperature of the top part 1b
Is maintained at about 50 to 60 (deg), the supersaturated layer A is easily obtained. This supersaturated layer A is charged particles 3 such as α particles.
When the vehicle passes, a row of fog droplets 5 is formed along the passage 4, and the tracks of the charged particles can be observed.

As the diffusion type fog box, there is a high-temperature diffusion type fog box in addition to the low-temperature diffusion type fog box described above. In the high-temperature diffusion type fog box, ethylene glycol is put in an observation tank and the upper part is heated by a heater or the like, and a similar temperature difference ΔT is formed to form a supersaturated layer.

[0004]

However, in the low-temperature diffusion type fog box described above, since consumables such as dry ice and liquid nitrogen are used as the cooling agent, it is necessary to prepare a cooling agent for each experiment. There is a disadvantage that experiments cannot be performed when it is difficult to obtain a coolant. Also,
Since cooling is performed using a coolant, cooling control cannot be easily performed, and it is difficult to maintain the temperature difference ΔT at an appropriate temperature. For example, if the entire observation tank 1 is cooled and ΔT is reduced, there is a disadvantage that the track becomes difficult to see. On the other hand, in the case of a high-temperature diffusion type fog chamber, an experiment can be easily performed because an electric heater or the like is used as a heating source, but when observing β rays, it is difficult to control the temperature and easily observe a track. There is a drawback that you can not.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a low-temperature diffusion type fog chamber in which the temperature can be easily controlled and the track of charged particles can be easily observed, and an observation jig for making it easier to observe the track during the track observation. Is to provide.

[0006]

An embodiment of the present invention will be described with reference to FIGS. (1) When described in association with FIG. 2, the invention of claim 1 is based on the bottom portion 1 of an observation tank 11 in which a track observation gas is sealed.
1a is cooled by a cooling means, and is applied to a low-temperature diffusion type fog box for observing the tracks of charged particles by forming a supersaturated layer of a track observing gas. To achieve. (2) In the low-temperature diffusion type fog box according to the first aspect of the present invention, the heating device 15 provided on the upper part of the observation tank 11 for heating the track observation gas, the upper part of the observation tank, Control means 19 is provided for controlling the electronic cooling element 12 and the heating device 15 so that the difference in the temperature of the track observation gas at the bottom is appropriately maintained. (3) Explaining in connection with FIG. 3, the invention of claim 3 is the low-temperature diffusion type fog box according to claim 1, which covers the heat radiating portion 12b of the electronic cooling element 12, and moves from the heat radiating portion 12b to the cooling portion 12a. A low-temperature diffusion type fog box, comprising a heat insulating member 10 for preventing heat from entering into the fog box. (4) Explained in connection with FIG. 4, the invention according to claim 4 is an observation jig 22 used for a fog box for observing tracks of charged particles emitted from the charged particle source 20 into the observation tank 11.
The above-described object is achieved by limiting the number of charged particles that enter the observation tank 11 from the charged particle source 20 and causing the charged particles to enter along the supersaturated layer A formed in the observation tank 11. To achieve.

[0007] In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments of the present invention are used to make the present invention easy to understand. However, the present invention is not limited to the embodiment.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a perspective view showing an embodiment of a low-temperature diffusion type fog box according to the present invention, and FIG. 2 is a view including a control system. 2A is a cross-sectional view of the fog box viewed from the side, and FIG.
It is -D sectional drawing. Reference numeral 12 denotes an electronic cooling element such as a Peltier element, and reference numeral 13 denotes a power supply. The electronic cooling element 12 is attached to the bottom surface 11a of the observation tank 11. 12a is a cooling unit of the electronic cooling element 12, 12b is a radiator, and 14 is a water cooling block for cooling the radiator 12b. The water cooling block 14 is provided with a cooling water passage 14c.
4a is a water supply port and 14b is a drain port. Note that FIG.
In (a), the drain port 14b is connected to the water supply port 1 for easy understanding.
4a is shown on the opposite side. Aluminum material, which is a material having good heat conductivity, is used for the bottom surface 11a, and polysulfone, which is a transparent member, is used for the top surface 11b and the side surface 11c. An electric heater 15 is provided near the upper surface of the side surface 11c, and 16 is a power supply for the electric heater.

A felt 17 or the like containing ethanol is placed in the electric heater portion in the observation tank 11. When the felt 17 is heated by the electric heater 15, the ethanol evaporates and the observation tank 1 is heated.
1 is filled with ethanol gas. Reference numerals 18a and 18b denote temperature sensors, which measure the temperatures of the upper and lower portions in the observation tank 11 by these. 19 is a temperature sensor 18a, 1
8b is a control device that controls the electronic cooling element 12 and the electric heater 15 based on the measurement value of the electronic cooling element 12 and the electric heater 15 so that the vertical temperature difference ΔT in the observation tank 11 is appropriately maintained. Is controlled. When observing the track of α particles using ethanol, ΔT
= 50 to 60 ° C. In the present embodiment, the temperature of the thermoelectric cooler 12 is set to about −20 ° C.
The temperature difference ΔT is maintained by controlling the temperature of the electric heater 15 to about 40 ° C., respectively.
The α particle beam source 20 is attached to the side surface portion 11c at a position where the supersaturated layer A is formed. Reference numeral 21 denotes a miscellaneous ion removing electrode for removing miscellaneous ions in the observation tank 11.

As described above, in this embodiment, in the low-temperature diffusion type fog box, the electronic cooling element 12 is used for cooling the bottom 11a of the observation tank. There is no need to prepare liquid nitrogen or dry ice, and experiments can be easily performed even in locations where these coolants are difficult to obtain. Further, an electric heater 15 is provided above the observation tank 11, and the outputs of the electronic cooling element 12 and the electric heater 15 are controlled so that the vertical temperature difference ΔT of the observation tank 11 is optimized. A can be easily formed.

The cooling section 12 of the electronic cooling element 12
Since the a and the heat radiating portion 12b are close to each other, as shown in FIG. 3A, heat enters the cooling portion 12a from the heat radiating portion 12b on the side surface portion of the electronic cooling element 12, and the cooling effect is reduced. In the present embodiment, as shown in FIG. 3B, a heat insulating member 10 is provided on the side surface of the electronic cooling element 12 so as to cover the heat radiating portion 12b, so that heat intrusion into the cooling portion 12a is reduced. .

FIG. 4 (a) shows the observation tank 1 from the α particle beam source 20.
FIG. 3 is a diagram conceptually showing the appearance of α particles released into the inside of the device. The α-particles emitted from the emission section 20a (circular hole) of the α-particle beam source 20 are emitted in the range of the solid angle Ω as shown in the figure. By the way, the thickness d of the formed supersaturated layer A
Is thin, for example, the track of α particles emitted at a large angle θ from the horizontal direction is short and difficult to observe. Also,
Since the number of emitted α-particles is larger as θ is smaller, the tracks of α-particles emitted in the horizontal direction are overlapped and are observed thick, blurred, and have a disadvantage that it is difficult to observe.

Therefore, in the present embodiment, a cap 22 as shown in FIG. 4B is attached to the tip of the α particle beam source 20 by utilizing the relatively small transmittance of the α particle beam. The emission of particles was limited. 5A and 5B are diagrams showing the cap 22 in detail, wherein FIG. 5A is a diagram of the cap 22 viewed from the front, and FIG. 5B is a diagram of the cap 22 viewed from the side. A slit 22a having a narrow groove width is formed in the cap 22 in the horizontal direction. As shown in FIG. 4B, α particles from the α particle source 21 are restricted by the cap 22, and α particles passing through the slit 22a are formed. Only particles are released into the observation tank 11.

At this time, since the groove width of the slit 22a is very narrow, the angle θ in FIG. 4B is also reduced, and the light is emitted almost horizontally, and the number of α particles emitted is also small. As a result, the α-particles are emitted horizontally to the supersaturated layer A and the track lengthens, and the number of tracks decreases because the number of α-particles is limited. Observation becomes easier. FIG. 4C is a view of the α particle beam source 20 as viewed from above the observation tank 11, and a broken line B indicates a track.

In the above-described embodiment, the case of observing α particles has been described. However, similar effects can be obtained for β rays. That is, the temperature difference can be easily managed, and the track can be easily observed.

In the correspondence between the embodiment described above and the elements of the claims, the electric heater 15 constitutes a heating device, and the cap 22 constitutes an observation jig.

[0017]

As described above, according to the first to third aspects of the present invention, since the electronic cooling element is used as the cooling means for the observation tank, nitrogen or dry ice or the like is used every time an experiment is performed as in the prior art. It is not necessary to prepare a coolant, and even when these coolants are difficult to obtain, an experiment of track observation can be easily performed. In particular, in the second aspect of the present invention, an electric heater is provided above the observation tank to control the temperature difference in the vertical direction in the observation tank appropriately, so that the supersaturated layer is easily formed. can do. Further, according to the third aspect of the invention, the heat insulation between the cooling part and the heat radiating part of the electronic cooling element is improved, so that the cooling effect of the electronic cooling element can be prevented from lowering. According to the invention of claim 4, since the number of charged particles incident on the supersaturated layer is reduced and the charged particles are incident along the supersaturated layer, the density of the track to be observed is reduced and the length of the track is reduced. , The track observation becomes easier.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a low-temperature diffusion type fog box according to the present invention.

FIGS. 2A and 2B are views showing the detail of the fog box of FIG. 1, wherein FIG. 2A is a cross-sectional view as viewed from the side, and FIG.

FIG. 3 is an enlarged view of the vicinity of an electronic cooling element 12 in FIG. 2,
(A) is a figure explaining the fall of a cooling effect, (b) is a figure explaining the heat insulation member 10. FIG.

FIGS. 4A and 4B are views for explaining how alpha particles are released in the observation tank 11. FIG.
(B), (c) shows the case where the cap 22 is provided,
(C) is a diagram viewed from the upper surface side of the observation tank 11.

5A and 5B are views showing the cap 22 in detail, wherein FIG. 5A is a front view and FIG. 5B is a side view.

FIG. 6 is a cross-sectional view illustrating a conventional low-temperature diffusion type fog box.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Insulation member 11 Observation tank 12 Electronic cooling element 14 Water cooling block 15 Electric heater 19 Control device 20 Alpha particle beam source 22 Cap A Supersaturated layer

Claims (4)

[Claims] 1. A low-temperature diffusion type fog box for cooling a bottom portion of an observation tank filled with a track observation gas by cooling means to form a supersaturated layer of the gas and observe tracks of charged particles. A low-temperature diffusion type fog box characterized by using an electronic cooling element as a means. 2. The low-temperature diffusion type fog box according to claim 1, wherein a heating device provided at an upper portion of the observation tank for heating a track observation gas, and for tracking a track at an upper portion and a bottom portion of the observation tank. A low-temperature diffusion type fog box, further comprising control means for controlling the electronic cooling element and the heating device so that a difference in gas temperature is appropriately maintained. 3. The low-temperature diffusion type fog box according to claim 1, further comprising a heat insulating member that covers a heat radiating portion of the electronic cooling element and prevents heat from entering the cooling portion from the heat radiating portion. Low-temperature diffusion type fog box. 4. An observation jig used for a fog box for observing tracks of charged particles emitted from a charged particle source into an observation tank, wherein the charged particles enter the observation tank from the charged particle source. Wherein the number of the charged particles is limited and the charged particles are incident along a supersaturated layer formed in the observation tank.