JP2004317686A - Cloud chamber for radiation observation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cloud chamber for radiation observation capable of enhancing cooling efficiency of the bottom part of an observation vessel main body. <P>SOLUTION: The cloud chamber 11 for radiation observation is constituted of the observation vessel main body 12 and an observation vessel main body storage box 13 which stores the observation vessel main body 12, etc. A heat insulating layer 14 is provided in the observation vessel main body storage box 13 and dry ice 15 is loaded on an inner bottom part of the heat insulating layer 14. In addition, a plurality of female screw holes 22a are equally provided like a lattice on the bottom plate 22 of the observation vessel main body 12 and male screws 23 for heat transfer made from stainless steel are screwed together in the respective female screw holes 22a. Irregularities 23a are carved in spiral on circumferential surfaces of the male screws 23 for heat transfer. Then, tip parts of the male screws 23 for heat transfer bitting into the dry ice 15 and their irregularities 23a are brought into contact with the dry ice 15 at a use state of the cloud chamber 11 for radiation observation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a radiation observation fog box for easily observing tracks of natural radiation in, for example, school education and social education in museums and the like.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a cloud box is used to observe a myriad of natural radiations emitted from space and the earth. The following are known as this type of fog box (for example, see Non-Patent Document 1). That is, the observation tank main body is placed on the upper surface of the substantially square plate-shaped dry ice, and a cloth containing a large amount of liquid alcohol is attached to the upper inner surface of the side wall of the observation tank main body. is there.
[0003]
The liquid alcohol contained in the cloth evaporates with the passage of time, and the atmosphere in the upper region of the observation tank main body becomes substantially saturated with alcohol vapor. Then, the alcohol vapor drops to the lower region inside the observation tank main body in a saturated state. Since the inside lower region of the observation tank main body is in a low temperature state by cooling with dry ice, a supersaturated region of alcohol vapor is formed in the lower inside region due to the temperature difference in the observation tank main body. When the natural radiation enters the supersaturated region, alcohol vapor is liquefied along the path of the natural radiation, and mist droplets are generated. The mist droplets are observed as tracks of natural radiation.
[0004]
[Non-patent document 1]
Bulletin of Kogakuin University High School 1980 No.22 p6-11
[0005]
[Problems to be solved by the invention]
However, since the bottom surface of the observation tank main body is flat in the above-described conventional fog box, if there is an uneven portion on the upper surface of the dry ice, the portion of the bottom surface of the observation tank main body that does not contact the dry ice and the portion that does not contact the dry ice. Occurs. That is, since the bottom surface located in a portion not in contact with the dry ice is not sufficiently cooled by heat transmitted from the outside, frost or ice adheres to the bottom surface. Therefore, there is a problem that the bottom surface of the observation tank main body is hardly cooled, and the cooling efficiency is reduced.
[0006]
The present invention has been made by paying attention to such problems existing in the related art. It is an object of the present invention to provide a radiation observation fog box that can improve the cooling efficiency of the bottom of the observation tank body.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, in the fog box for radiation observation according to the first aspect of the present invention, a solvent for track observation is sealed inside an observation tank main body having a bottomed box shape, and a track observation is provided on an upper part. A heating means for generating a vapor of the solvent for use is provided, a dry ice for cooling a bottom of the observation tank body is provided at a lower portion, and a light source for irradiating the inside of the observation tank body is provided on an outer periphery of the observation tank body. A radiation observation fog box for observing radiation traces by forming a supersaturated region of the vapor for the trace observation solvent using the temperature difference between the upper region and the lower region in the observation tank body. A plurality of projections are provided on the bottom of the observation tank main body, and each projection cuts into dry ice, so that the bottom is cooled by a heat transfer action from the dry ice to each projection. Is characterized by .
[0008]
According to a second aspect of the present invention, in the fog box for radiation observation according to the first aspect of the present invention, the bottom of the observation tank main body and each projection are made of a metal having excellent thermal conductivity. Things.
[0009]
According to a third aspect of the present invention, there is provided the radiation observation fog box according to the first or second aspect, wherein the projections are provided with an uneven portion on an outer surface thereof. , Characterized in that the heat transfer area of the projection with respect to dry ice is increased.
[0010]
According to a fourth aspect of the present invention, in the radiation observation fog box according to any one of the first to third aspects, the projections are provided evenly over the entire bottom portion of the observation tank body. It is characterized by being carried out.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the radiation observation fog box 11 includes an observation tank main body 12, an observation tank main body storage box 13 that supports the observation tank main body 12, and the like.
[0012]
First, the observation tank main body storage box 13 will be described. The observation tank main body storage box 13 is formed of a synthetic resin in the shape of a bottomed square box having an opening at an upper end. A heat insulating layer 14 made of a polystyrene foam is provided below the projecting piece 13a projecting inward from the upper inner surface of the observation tank main body housing box 13. A square plate-shaped dry ice 15 is placed on the inner bottom of the heat insulating layer 14.
[0013]
Further, on the open end surface of the observation tank main body storage box 13, storage pieces 13b having an inverted L-shaped cross section are provided so as to protrude over the four sides thereof, and a light source is provided in a space between the storage piece 13b and the protruding piece 13a. The white light emitting diode 16 is accommodated. Recesses 13c are provided at the four corners at the bottom of the observation tank main body storage box 13, and a female screw member 17 made of metal is attached to each of the recesses 13c. A male screw 18 for adjusting the position is screwed into each female screw member 17, and the male screw 18 for adjusting the position can adjust the position of the observation tank main body housing box 13 in the vertical direction.
[0014]
Next, the observation tank body 12 will be described. The observation tank main body 12 has an opening at the upper end, a peripheral wall made of a transparent synthetic resin such as polycarbonate, and a bottomed square box-like shape having an aluminum bottom plate 22 with excellent heat conductivity attached to the bottom. Is formed. The observation tank body 12 is placed on the upper surface of the dry ice 15, and the entire bottom plate 22 is in contact with the dry ice 15. As shown in FIGS. 2 and 3, a plurality of female screw holes 22 a as screw holes are evenly screwed in a lattice pattern on the bottom plate 22 of the observation tank main body 12, and each of the female screw holes 22 a has a thermal conductivity as a protrusion. The heat transfer male screw 23 made of stainless steel, which is excellent in quality, is screwed.
[0015]
The male screw 23 for heat transfer has a columnar shape, and a hexagonal hole (not shown) is formed in a distal end surface thereof. In addition, an uneven portion 23 a formed by a screw thread and a screw groove is formed on the outer peripheral surface of the male screw 23 for heat transfer. By fitting the tip of a hexagon wrench into the hexagonal hole of the heat transfer male screw 23 and rotating, the base end of the heat transfer male screw 23 is screwed into the female screw hole 22 a of the bottom plate 22 of the observation tank body 12. It is supposed to be. When the radiation observation fog box 11 is in use, the distal end of the heat transfer male screw 23 bites into the dry ice 15.
[0016]
On the upper end surface of the peripheral wall of the observation tank main body 12, a storage groove 27 for storing ethyl alcohol 26 as a solvent for track observation is formed in a concave shape. Each of the storage grooves 27 accommodates a nichrome wire 28 as a heating means, and the ethyl alcohol 26 is evaporated by heat generated by energizing the nichrome wire 28. A support hole 29 is provided in the upper part of the right side wall of the observation tank main body 12, and a temperature sensor 30 is inserted and supported in the support hole 29.
[0017]
A rectangular plate-shaped lid member 20 is placed on the upper end opening surface of the observation tank main body 12, and the observation tank main body 12 is sealed by the lid member 20. The lid member 20 is composed of a pair of glass plates 19 and a heater 21 made of a conductive film as a heating means sandwiched between the pair of glass plates 19, and the heater 21 generates heat when energized. Further, a voltage for removing miscellaneous ions is applied between the heater 21 and the bottom plate 22 so that miscellaneous ions in the observation tank main body 12 are removed.
[0018]
Next, the operation of the radiation observation fog box 11 will be described below.
Now, in order to observe the trace of radiation using the radiation observation fog box 11, first, dry ice 15 is placed on the inner bottom of the heat insulating layer 14 of the observation tank main body storage box 13. Next, the observation tank main body 12 is placed on the upper surface of the dry ice 15, and the tip of each male screw 23 for heat transfer is made to bite into the dry ice 15. Subsequently, after the ethyl alcohol 26 is stored in the storage groove 27, the lid member 20 is put on the upper opening surface of the observation tank main body 12, and the inside of the observation tank main body 12 is sealed.
[0019]
Next, a current is applied to the nichrome wire 28 to cause the nichrome wire 28 to generate heat and to heat the ethyl alcohol 26. At this time, the atmosphere in the upper region in the observation tank main body 12 is substantially saturated with ethyl alcohol vapor. In addition, the heater 21 is energized to generate heat, so that the temperature of the upper region in the observation tank main body 12 is heated to 20 ° C. At this time, the current flowing through the heater 21 is controlled based on the output of the temperature sensor 30, so that the temperature of the upper region in the observation tank main body 12 is maintained at 20 ° C.
[0020]
Further, since the inside of the observation tank main body 12 is sealed by the lid member 20 and the flow of the air is suppressed, the ethyl alcohol vapor falls to the lower region in the observation tank main body 12 in a saturated state.
[0021]
On the other hand, at the bottom of the observation tank main body 12, the distal end of each heat transfer male screw 23 bites into the dry ice 15, and the uneven portion 23 a comes into contact with the dry ice 15. The contact area between the surface and the dry ice 15 increases. Then, the heat transfer area of the distal end of the heat transfer male screw 23 to the dry ice 15 increases, and each heat transfer male screw 23 cools to almost the same temperature as the dry ice 15 by the heat transfer action from the dry ice 15. Is done. At the same time, the bottom plate 22 of the observation tank main body 12 is cooled to substantially the same temperature as the male screw 23 for heat transfer by the heat transfer action from the male screw 23 for heat transfer. At this time, since the male screw 23 for heat transfer is provided in a lattice shape over the entire bottom plate 22, the temperature distribution of the bottom plate 22 becomes uniform, and the bottom plate 22 is uniformly cooled over the whole. As a result, the lower region in the observation tank main body 12 is cooled to about −50 ° C. with the cooling of the bottom plate 22 of the observation tank main body 12, and that state is maintained.
[0022]
The ethyl alcohol vapor that has descended to the lower region in the observation tank main body 12 is cooled, and as shown in FIG. 4, a supersaturated region 31 due to the ethyl alcohol vapor is formed in the lower region in the observation tank main body 12. When the radiation 32 passes through the supersaturated region 31, the ethyl alcohol vapor in the supersaturated region 31 is liquefied, and along with the radiation, mist 33 of the ethyl alcohol 26 is generated along the radiation 32. Then, the mist droplets 33 are observed as tracks of the radiation 32.
[0023]
At this time, a voltage for removing miscellaneous ions is applied to the inside of the observation tank body 12 to remove the miscellaneous ions, so that the track of the radiation 32 is clearly observed. Further, since the lower region in the observation tank main body 12 is illuminated by the white light emitting diode 16, a clearer track of the radiation 32 is observed. When the dry ice 15 sublimates as time passes, the state in which the bottom plate 22 of the observation tank main body 12 abuts on the upper surface of the dry ice 15 due to the gravity of the observation tank main body 12 is maintained. Therefore, cooling of the lower region in the observation tank main body 12 is maintained for a long time.
[0024]
The effects exerted by the above embodiment will be described below.
The bottom plate 22 of the observation tank main body 12 is provided with a plurality of male screws 23 for heat transfer over the entirety thereof. When observing the trace of the radiation 32, the distal end of each male screw 23 for heat transfer is made of dry ice 15. It is designed to bite into. At this time, each heat transfer male screw 23 is directly cooled by the dry ice 15, and the bottom plate 22 is cooled over a wide range by the heat transfer action from the cooled heat transfer male screw 23 to the bottom plate 22. That is, when the radiation observation fog box 11 is in use, the heat taken by the dry ice 15 is significantly larger than the heat taken by the bottom plate 22 from the air.
[0025]
For this reason, compared to the conventional configuration in which frost or ice adheres to the bottom of the observation tank body 12 and the cooling efficiency decreases, adhesion of frost or ice to the bottom plate 22 of the observation tank body 12 is suppressed, and the observation tank body 12 The cooling efficiency of the lower region inside can be improved.
[0026]
In addition, the radiation observation fog box 11 includes an aluminum bottom plate 22 having excellent heat conductivity and a stainless steel heat transfer male screw 23. Therefore, the cold heat of the dry ice 15 is quickly transmitted to the bottom plate 22 via the male screw 23 for heat transfer. Therefore, the cooling efficiency of the lower region in the observation tank main body 12 can be further improved. Further, even when the radiation observation fog box 11 is used for a long period of time, it is possible to suppress the adhesion of rust to the heat transfer male screw 23.
[0027]
Further, an uneven portion 23 a is provided on the outer surface of each male screw 23 for heat transfer, and the uneven portion 23 a comes into contact with the dry ice 15. That is, the contact area between the tip of the heat transfer male screw 23 and the dry ice 15 increases, and the heat transfer area of the tip of the heat transfer male screw 23 to the dry ice 15 increases. Therefore, the heat transfer effect from the dry ice 15 to the heat transfer male screw 23 can be improved.
[0028]
In addition, the heat transfer male screw 23 is evenly provided in a grid pattern over the entire bottom plate 22 of the observation tank main body 12. That is, the bottom plate 22 of the observation tank main body 12 is cooled sequentially from the contact portion with each of the male screws 23 for heat transfer cooled by the transmission of the cold heat of the dry ice 15, and as a result, the temperature distribution of the bottom plate 22 becomes uniform. For this reason, the bottom plate 22 of the observation tank main body 12 is uniformly cooled throughout, and accordingly, the lower region in the observation tank main body 12 can be uniformly cooled.
[0029]
The male screw 23 for heat transfer is screwed into the female screw hole 22 a with its base end located in the bottom plate 22 of the observation tank body 12. That is, the bottom plate 22 is configured to be flat without a part of the male screw 23 for heat transfer protruding from the bottom plate 22. For this reason, when the observer observes the trace of the radiation 32 from above the observation tank main body 12, the trace is observed against the background of the bottom plate 22 having no obstructive projection, and the clear trace of the radiation 32 is observed. be able to.
[0030]
A plurality of white light emitting diodes 16 are provided on the outer periphery of the observation tank main body 12, and when observing the trace of the radiation 32, the lower region in the observation tank main body 12 is irradiated by the white light emitting diodes 16. ing. That is, since the mist droplet 33 of the ethyl alcohol 26 is irradiated by the white light emitting diode 16, a clearer track of the radiation 32 can be observed.
[0031]
This embodiment can be embodied with the following modifications.
The projection may be formed integrally with the bottom plate 22 of the observation tank body 12. That is, the bottom plate 22 of the observation tank main body 12 is provided with projections having an inverted triangular cross section evenly over the entire bottom plate 22.
[0032]
-The protrusion may be changed to a nail member or the like.
The protrusion may be made of a metal having excellent thermal conductivity such as aluminum.
The track observation solvent may be changed to another alcohol such as methyl alcohol.
[0033]
The bottom plate 22 may be made of stainless steel or the like.
Further, technical ideas that can be grasped from the embodiment will be described below.
4. The apparatus according to claim 1, wherein a plurality of screw holes are screwed on a bottom outer surface of the observation tank main body, and a male screw as a protrusion is screwed into the screw hole. 5. Fog box for radiation observation described in 4.
[0034]
【The invention's effect】
As described above, according to the present invention, the following effects can be obtained.
According to the fog box for radiation observation of the first aspect of the invention, the cooling efficiency of the bottom of the observation tank main body can be improved.
[0035]
According to the radiation observation fog box of the second aspect, the effect of the first aspect can be improved.
According to the fog box for radiation observation of the third aspect, in addition to the effect of the first or second aspect, the effect of heat transfer from the dry ice to the projections can be improved.
[0036]
According to the radiation observation fog box of the invention described in claim 4, in addition to the effect of the invention described in any one of claims 1 to 3, the bottom of the observation tank main body is uniformly cooled. Can be.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing a radiation observation fog box according to an embodiment.
FIG. 2 is a partially enlarged sectional view showing a bottom plate of an observation tank main body of the radiation observation fog box.
FIG. 3 is a sectional view taken along line 3-3 in FIG. 1;
FIG. 4 is a schematic explanatory view when observing a track of radiation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Radiation observation fog box, 12 ... Observation tank main body, 15 ... Dry ice, 16 ... White light emitting diode as a light source, 21 ... Heater as a heating means, 22 ... Bottom plate constituting a bottom part, 23 ... Transmission as a projection Male screw for heat, 23a: Uneven portion, 26: Ethyl alcohol as solvent for track observation, 28: Nichrome wire as heating means, 31: Supersaturated region, 32: Radiation.

Claims (4)

A solvent for track observation is sealed inside the observation tank main body having a bottomed box shape, a heating means for generating vapor of the track observation solvent is provided at an upper part, and a bottom part of the observation tank main body is provided at a lower part. Is provided, and a light source for irradiating the inside of the observation tank body is provided on the outer periphery of the observation tank body, and a temperature difference between an upper region and a lower region thereof is used in the observation tank body. A radiation observation fog chamber for forming a supersaturated region of the vapor of the solvent for track observation and observing the track of radiation,
A plurality of projections are provided on the bottom of the observation tank main body, and the projections are configured to bite into dry ice, so that the bottom is cooled by a heat transfer action from the dry ice to each projection. A fog box for radiation observation characterized by the following. The fog box for radiation observation according to claim 1, wherein the bottom portion and each projection of the observation tank main body are made of metal having excellent thermal conductivity. The unevenness | corrugation part is provided in the outer surface of the said protrusion, and when each protrusion bites into dry ice, it is comprised so that the heat transfer area of the protrusion with respect to dry ice may be increased. Fog box for radiation observation. The fog box for radiation observation according to any one of claims 1 to 3, wherein the projections are provided uniformly over the entire bottom portion of the observation tank body.

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