- Email: [email protected]
SSNTDs in the automatic detector of radon
Radiation Measurements 39 (2005) 115 – 119 www.elsevier.com/locate/radmeas
Short communication
SSNTDs in the automatic detector of radon I. Nevinsky∗ , T. Tsvetkova Research Center of Natural Radioactivity, Frunze Str. 82, Kholmsky, Abinsk Distr., Krasnodar region, Krasnodar 353302, Russia Received 12 May 2003; received in revised form 19 April 2004; accepted 19 April 2004
Abstract The simple automatic detector with application solid state nuclear track detectors is described. The tape of LR-115 is reeled up on the cylinder connected with a clockwork. One revolution of the cylinder occurs for 2 weeks. All devices are in the pipe, which is dug in the soil. The special adaptation enables to exhibit the certain site of a tape during the chosen interval of time. Results of measurement of radon with the help of such a detector on the mud volcano and in the cave are shown. Good concurrence of the results received by different detectors is observed. The daily data from detectors, which simultaneously worked in the Krasnodar territory (Russia), were imposed on the map of region. It has been noticed, that areas of high concentration of soil radon move to that side where the earthquake occurs. © 2004 Published by Elsevier Ltd. Keywords: SSNTDs; Radon; Automatic detector; Clockwork; Mud volcano; Cave; Earthquakes
1. Introduction For the decision of many tasks of geology, geophysics, geochemistry and ecology, it is necessary to measure radon in the water and air. For this purpose, most different detectors are used (Monnin and Seidel, 1992). In the Krasnodar region (Northern Caucasus), the soil radon since 1996 is measured. With the purpose of the forecast of earthquakes, electronic detectors with automatic record of saved up information are used. For measurements, each hour semiconductor counters “Rn-probe CLLIPERTON-II” (France) with the photodiode of 1 cm in diameter as a basic gauge, are used. For measurements, detectors with scintillations every 5 min (ZnS (Ag)), with the photomultipliers in diameter 8 cm, are used. Both kinds of detectors represent the pipes of different diameter (5 and 10 cm) and they are dug in the ground at a depth of 60 cm by the open end downwards (Tsvetkova et al., 2001). The ∗ Corresponding author.
E-mail address: [email protected] (I. Nevinsky) 1350-4487/$ - see front matter © 2004 Published by Elsevier Ltd. doi:10.1016/j.radmeas.2004.04.014
length of the pipes does not exceed 50 cm. Counters of radon are removed from the open end of the pipe at 25 cm. These devices work in an automatic mode, but sometimes spoil. For scintillation counters, work powerful accumulators are required. It is necessary to periodically calibrate electronic detectors for stability of their parameters. Cost of electronic detectors is high. For studying distribution of radon in the soil in the territory of mud volcanoes, in breaks and caves solid state nuclear track detectors (SSNTDs) were applied (Nevinsky et al., 2001). SSNTDs no more than 1 cm2 were attached to the bottom of plastic glasses with volume of 0.5 l. Glasses were dug in the ground too at a depth of 60 cm. Detectors were dug out after some days of an exposition in the soil. The concentration of radon in varied soils in the Northern Caucasus are such, that the statistically necessary number of -tracks was collected even for 1 day. Then SSNTDs were processed in the chemical laboratory by alkali. The number of the -tracks were counted with a microscope. SSNTDs are very simple in operation. They do not spoil. Sources of electricity are not necessary for them. Because of these properties to create the cheap counter of soil radon by
116
I. Nevinsky, T. Tsvetkova / Radiation Measurements 39 (2005) 115 – 119
using SSNTD, which can also work in an automatic mode as electronic detector, has been solved.
9 1 8
2. The automatic detector of radon In Fig. 1, the automatic detector of radon in which are SSNTDs applied is shown. The device has two pipes of diameters 20 cm (1) and 10 cm (2) between which there is a partition with a rectangular aperture. In a smaller pipe, there is a diffusion of radon from the soil to the detector. In the big pipe all mechanisms and SSNTD are located. The strip of film LR-115 is of width 1 cm and length of 28 cm on the cylinder 3, with the clockwork fixed inside. The diameter of the cylinder is 9 cm. One full revolution of the cylinder occurs for 2 weeks. Then for 1 day, strip LR115 is displaced by 2 cm. The axis of the cylinder with a clockwork is fixed horizontally in the big pipe so, that piece of LR-115 is very close to an aperture in a partition. For change SSNTD and start of a clockwork, the cylinder 3 is easily taken out outside. Strip LR-115 from radon which can be in the top pipe 1 with the teflon circle strip 4 is protected. If one is simply to move the strip at an aperture in the partition it will be difficult to understand, to what moment of time what quantity of -tracks on a film corresponds. Therefore, it is necessary, that for the chosen interval of time of an exposition against the open end of a pipe 2, there is a similar piece of film LR-115. For the unit of time of measurement 1 day has been chosen. For exhibiting within a day piece of film of 2 cm length, the device shown at the left is used. Teflon plate 5 with the rectangular aperture in the size of 1 cm ×2 cm can move in the directions shown by the pointers. The sizes of the rectangular aperture correspond to width and length LR-115 on which it is displaced for 1 day. Due to ledges on a rotating pipe 3, the plate is shifted to the left, together with LR-115. For 1 day the -particle from radon in the pipe 2 thus gets on the same site of the film. When the day comes to an end, the ledge leaves contact with the plate. Under action of the spring 6, the plate comes back to the right. Further, the plate by following the ledge again starts to move. Such movement of a plate occurs every day. By changing the sizes of an aperture in the plate 5 and the number of ledges on the cylinder it is possible to choose different times for exhibiting SSNTD. The plate goes in one plane, and a surface of the pipe 3 goes on a circle. Besides working piece LR-115 for a day changes the position in a pipe. Because of it, for example, at the same concentration of radon in the soil at various times of the day on a working site of a film, there will be different number of the -tracks. But, as have shown by measurements with standard -sources, this error does not exceed 5%. Thermostabilization of the device by polyfoam 8 is carried out. When changed SSNTD, polyfoam is taken out, and all devices remain in the ground. The device is usually dug at a level of soil 9. To the bottom of the pipe 1 the teflon plate 7 is attached which is shifted manually by turning the
60cm 4 7 3
2 5
6
25cm
Fig. 1. Design of the automatic detector with SSNTDs. At the left, the device for an exposition of the same site of the tape for the chosen interval of time is shown. 1—pipe in diameter of 200 mm; 2—pipe in diameter of 100 mm; 3—the cylinder with strip LR-115; 4—teflon “protection”; 5—plate with rectangular aperture; 6—spring; 7—plate with the handle which closes working volume during change SSNTDs; 8—polyfoam.
handle, and the working aperture is closed during change SSNTD. It is necessary that during replacement SSNTD and start-up of a clockwork, atmospheric air do not mix up with soil air in pipe 2. The clockwork and cylinder are used from the standard meteorological devices for recording temperature, pressure or humidity. Speed of rotation of the cylinder has been lowered by up to one revolution in 2 weeks. Practically all details of the device (except for a clockwork) have been manually made within 1 day. Calibration of the created detector was carried out by comparison of the quantity of tracks with data of the semiconductor detector which has been dug near, the ground. All characteristics of the made counter correspond to usual SSNTDs (1 track/day cm2 corresponds to 1.3 Bq/m3 Rn in soil), which are described in (Tsvetkova et al., 2001; Nevinsky et al., 2001). After exhibiting tape, SSNTD was removed from the cylinder, cut on the sites corresponding to each day (length of 2 cm) and was exposed to standard chemical procedure. The number of tracks was considered in an optical microscope. 3. Results of measurement of radon with the help of the created device 3.1. Measurements in the mud volcanoes and in the caves Further, it was necessary to check up, how the new device works in real conditions. These two gauges have been
I. Nevinsky, T. Tsvetkova / Radiation Measurements 39 (2005) 115 – 119
117
Fig. 2. The map of Krasnodar territory. Points show places of measurement of soil radon. A—mud volcano “Miska” in Temruk. B—“Azishskaya” cave. I-2, II-1, II-2, II-3—places of simultaneous measurement of soil radon.
Temruk Azishskaya
2002-07_Rn-probe 30000 25000
Bq/m3
placed in the soil in “Azishskaya” cave and in the mud volcano “Miska” in Temruk (near Azov Sea). In these places, electronic semiconductor detectors already worked. The data from these gauges for geochemical tasks were used independently from each other. Fig. 2 shows a map of radon observation stations. Automatic devices with SSNTDs were placed close to the electronic detectors. In Fig. 3, as an example day-to-day changes of concentration of the soil radon received with the help of different detectors, is shown.
20000 15000 10000 5000 0 1
3
5
7
9
11 13 15 17 19 date
Temruk Azishskaya
2002-07_SSNTD
3.2. Simultaneous measurements of the several detectors on the large surface
21 23 25 27 29 31
25000
Bq/m3
20000
Since 2002, simultaneous measurements of the soil radon in the different items in the territory of Krasnodar region for a problem of the forecast of earthquakes are also begun. The distance between items is 50 km. In the points I-2, II-1, II2, II-3 (Fig. 2) automatic detectors with SSNTDs have been placed in the ground close to electronic scintillation detectors ZnS (Ag). Strip LR-115 varied every week. Changes of the average daily data, received from both kinds of detectors, coincided within the limits of mistakes. Thus, results which have been received with application of scintillation detectors have been confirmed. In Fig. 4, as an example, pictures of daily average concentration of soil radon in the territory of Krasnodar region, measured by data processing simultaneously from all detectors, are shown. Detectors are located in places of crossing
15000 10000 5000 0 1
3
5
7
9
11 13 15 17 19 21 23 25 27 29 31 date
Fig. 3. Changes of concentration of radon in the soil in the cave and in the mud volcano from day-to-day. The top figure shows the data of the electronic detector (Rn-probe). The bottom figure shows the data of the automatic detector with SSNTDs.
of vertical and horizontal lines. The data in figures resulted in relative units. The darker stain corresponds to high concentration of radon in the soil (up to 1200 Bq/m3 ).
118
I. Nevinsky, T. Tsvetkova / Radiation Measurements 39 (2005) 115 – 119 26.09.02
25.09.02 III
III
II
II
I 1
2
3
I 1
2
3
27.09.02
28.09.02
III
II
II
I 1
2
3
III
1
2
I 3
Fig. 4. Fields of different concentrations of radon in the soil (in relative units. Darker stain corresponds to higher concentration of radon) in territory of Krasnodar region on different days between September, 25, 2002, on September, 28, 2002. Crossings of direct lines of the maps correspond to places of accommodation of the gauges shown in Fig. 2. The big circle designates the place where the earthquake happened at 28.09.2002 in Abrau-Durso.
Accordingly, the lightest stain corresponds to the lowest concentration of radon (no more than 600 Bq/m3 ).
4. Discussion As shown in Fig. 3, changes of the average daily data from different kinds of detector of radon coincide within the limit of mistakes. As experiment, in the specified places, automatic detectors with SSNTD have been left only. It was revealed that the concentration of radon in the soil in the mud volcano “Miska” in Temruk strongly varies on a dayto-day basis. Strong rises and downturn of concentration of radon in a duration of 5–7 days were observed. After these strong changes which lasted some months the increased output of gas and water from gryphones was observed. On walls of the houses located near a volcano, there were cracks. Further concentration of radon went down sharply and was constantly low for a few months. In the “Azishskaya” cave, more stable data are observed. Measurements in the air of the cave with application of sedimentation of radon daughter nuclides on paper filters show its high concentration on the average 1300 Bq/m3 . However, strong deviations of concentration of radon in the air in this or that side are observed. Thus, there is a connection of Rn—concentration in the air of the cave with Rn—concentration in the soil. In Fig. 4, results show movement of the increased concentration of the soil radon in the Krasnodar territory on a day-to-day basis. The increased concentration of radon (dark stain) in the left part of the map on 25.09.2002 corresponds to the place of presence of mud volcanoes in Taman. Further moving the dark stain to item I-2 (settlement Abrau-Durso) within 4 days is observed. Abrau-Durso is designated in Fig. 4 by a circle. There was a local earthquake of average force on 28.09.2002. The increased concentration of radon again has returned on the following day to the condition similar as 25.09.2002. It is necessary to specify, that from September, 25th till September, 30th, essential changes of meteorological parameters were not observed. Similar movements of
high concentration of radon to the side where there was an earthquake, was repeatedly observed.
5. Conclusion In this article, very simple and cheap detector of soil radon on basis SSNTDs, working in an automatic mode, is described. The detector can be created by any person in any laboratory without special equipment. Any unqualified worker can make changes in SSNTDs. Only the clockwork in new detectors is a mechanical detail, therefore the detector practically is unique and does not spoil. Many hours are necessary to oil them once in a while. The Rn concentrations in many soils are such, that it is possible to obtain a statistically significant amount given every day. If it is necessary to raise sensitivity of the detector before SSNTD, the metal grid with a voltage of 700–800 V can be located. This voltage can be received from a very simple generator. Thus, the small battery can produce the necessary current within several months. Application of such a method shows increase in the number of tracks in a film some times due to increase of collection of daughter nuclides of radon. It will allow to obtain a statistically significant data at low concentration of radon in the soil air. Application of the described detectors in mud volcanoes helps to study laws in the change of their activity. The data from such detectors allow to supervise concentration of radon in the ground of a cave and to warn people working in excursion business of high concentration of radon in air of a cave. Simultaneous measurements of radon in the big area can be used for definition of the place of a probable earthquake. And for this purpose the simple and cheap detectors described can be used.
Acknowledgements We thank the Krasnodar Department of science and education for the financial support.
I. Nevinsky, T. Tsvetkova / Radiation Measurements 39 (2005) 115 – 119
References Monnin, M., Seidel, J., 1992. Radon in soil-air and in groundwater related to major geophysical events: a survey. Nucl. Instrum. Methods: Phys. Res. A 314, 316–330. Nevinsky, I., Nevinsky, V., Panyushkin, V., Ferronsky, V., Tsvetkova, T., 2001. An attempt to determine the tritium, 22 Na,
119
36 Cl and radon in territory of mud volcano in Taman. Radiat. Meas. 34, 349–353. Tsvetkova, T., Monnin, M., Nevinsky, I., Perelygin, V., 2001. Research on variation of radon and gamma-background as a prediction of earthquakes in the Caucasus. Radiat. Meas. 33, 1–5.
Short communication
SSNTDs in the automatic detector of radon I. Nevinsky∗ , T. Tsvetkova Research Center of Natural Radioactivity, Frunze Str. 82, Kholmsky, Abinsk Distr., Krasnodar region, Krasnodar 353302, Russia Received 12 May 2003; received in revised form 19 April 2004; accepted 19 April 2004
Abstract The simple automatic detector with application solid state nuclear track detectors is described. The tape of LR-115 is reeled up on the cylinder connected with a clockwork. One revolution of the cylinder occurs for 2 weeks. All devices are in the pipe, which is dug in the soil. The special adaptation enables to exhibit the certain site of a tape during the chosen interval of time. Results of measurement of radon with the help of such a detector on the mud volcano and in the cave are shown. Good concurrence of the results received by different detectors is observed. The daily data from detectors, which simultaneously worked in the Krasnodar territory (Russia), were imposed on the map of region. It has been noticed, that areas of high concentration of soil radon move to that side where the earthquake occurs. © 2004 Published by Elsevier Ltd. Keywords: SSNTDs; Radon; Automatic detector; Clockwork; Mud volcano; Cave; Earthquakes
1. Introduction For the decision of many tasks of geology, geophysics, geochemistry and ecology, it is necessary to measure radon in the water and air. For this purpose, most different detectors are used (Monnin and Seidel, 1992). In the Krasnodar region (Northern Caucasus), the soil radon since 1996 is measured. With the purpose of the forecast of earthquakes, electronic detectors with automatic record of saved up information are used. For measurements, each hour semiconductor counters “Rn-probe CLLIPERTON-II” (France) with the photodiode of 1 cm in diameter as a basic gauge, are used. For measurements, detectors with scintillations every 5 min (ZnS (Ag)), with the photomultipliers in diameter 8 cm, are used. Both kinds of detectors represent the pipes of different diameter (5 and 10 cm) and they are dug in the ground at a depth of 60 cm by the open end downwards (Tsvetkova et al., 2001). The ∗ Corresponding author.
E-mail address: [email protected] (I. Nevinsky) 1350-4487/$ - see front matter © 2004 Published by Elsevier Ltd. doi:10.1016/j.radmeas.2004.04.014
length of the pipes does not exceed 50 cm. Counters of radon are removed from the open end of the pipe at 25 cm. These devices work in an automatic mode, but sometimes spoil. For scintillation counters, work powerful accumulators are required. It is necessary to periodically calibrate electronic detectors for stability of their parameters. Cost of electronic detectors is high. For studying distribution of radon in the soil in the territory of mud volcanoes, in breaks and caves solid state nuclear track detectors (SSNTDs) were applied (Nevinsky et al., 2001). SSNTDs no more than 1 cm2 were attached to the bottom of plastic glasses with volume of 0.5 l. Glasses were dug in the ground too at a depth of 60 cm. Detectors were dug out after some days of an exposition in the soil. The concentration of radon in varied soils in the Northern Caucasus are such, that the statistically necessary number of -tracks was collected even for 1 day. Then SSNTDs were processed in the chemical laboratory by alkali. The number of the -tracks were counted with a microscope. SSNTDs are very simple in operation. They do not spoil. Sources of electricity are not necessary for them. Because of these properties to create the cheap counter of soil radon by
116
I. Nevinsky, T. Tsvetkova / Radiation Measurements 39 (2005) 115 – 119
using SSNTD, which can also work in an automatic mode as electronic detector, has been solved.
9 1 8
2. The automatic detector of radon In Fig. 1, the automatic detector of radon in which are SSNTDs applied is shown. The device has two pipes of diameters 20 cm (1) and 10 cm (2) between which there is a partition with a rectangular aperture. In a smaller pipe, there is a diffusion of radon from the soil to the detector. In the big pipe all mechanisms and SSNTD are located. The strip of film LR-115 is of width 1 cm and length of 28 cm on the cylinder 3, with the clockwork fixed inside. The diameter of the cylinder is 9 cm. One full revolution of the cylinder occurs for 2 weeks. Then for 1 day, strip LR115 is displaced by 2 cm. The axis of the cylinder with a clockwork is fixed horizontally in the big pipe so, that piece of LR-115 is very close to an aperture in a partition. For change SSNTD and start of a clockwork, the cylinder 3 is easily taken out outside. Strip LR-115 from radon which can be in the top pipe 1 with the teflon circle strip 4 is protected. If one is simply to move the strip at an aperture in the partition it will be difficult to understand, to what moment of time what quantity of -tracks on a film corresponds. Therefore, it is necessary, that for the chosen interval of time of an exposition against the open end of a pipe 2, there is a similar piece of film LR-115. For the unit of time of measurement 1 day has been chosen. For exhibiting within a day piece of film of 2 cm length, the device shown at the left is used. Teflon plate 5 with the rectangular aperture in the size of 1 cm ×2 cm can move in the directions shown by the pointers. The sizes of the rectangular aperture correspond to width and length LR-115 on which it is displaced for 1 day. Due to ledges on a rotating pipe 3, the plate is shifted to the left, together with LR-115. For 1 day the -particle from radon in the pipe 2 thus gets on the same site of the film. When the day comes to an end, the ledge leaves contact with the plate. Under action of the spring 6, the plate comes back to the right. Further, the plate by following the ledge again starts to move. Such movement of a plate occurs every day. By changing the sizes of an aperture in the plate 5 and the number of ledges on the cylinder it is possible to choose different times for exhibiting SSNTD. The plate goes in one plane, and a surface of the pipe 3 goes on a circle. Besides working piece LR-115 for a day changes the position in a pipe. Because of it, for example, at the same concentration of radon in the soil at various times of the day on a working site of a film, there will be different number of the -tracks. But, as have shown by measurements with standard -sources, this error does not exceed 5%. Thermostabilization of the device by polyfoam 8 is carried out. When changed SSNTD, polyfoam is taken out, and all devices remain in the ground. The device is usually dug at a level of soil 9. To the bottom of the pipe 1 the teflon plate 7 is attached which is shifted manually by turning the
60cm 4 7 3
2 5
6
25cm
Fig. 1. Design of the automatic detector with SSNTDs. At the left, the device for an exposition of the same site of the tape for the chosen interval of time is shown. 1—pipe in diameter of 200 mm; 2—pipe in diameter of 100 mm; 3—the cylinder with strip LR-115; 4—teflon “protection”; 5—plate with rectangular aperture; 6—spring; 7—plate with the handle which closes working volume during change SSNTDs; 8—polyfoam.
handle, and the working aperture is closed during change SSNTD. It is necessary that during replacement SSNTD and start-up of a clockwork, atmospheric air do not mix up with soil air in pipe 2. The clockwork and cylinder are used from the standard meteorological devices for recording temperature, pressure or humidity. Speed of rotation of the cylinder has been lowered by up to one revolution in 2 weeks. Practically all details of the device (except for a clockwork) have been manually made within 1 day. Calibration of the created detector was carried out by comparison of the quantity of tracks with data of the semiconductor detector which has been dug near, the ground. All characteristics of the made counter correspond to usual SSNTDs (1 track/day cm2 corresponds to 1.3 Bq/m3 Rn in soil), which are described in (Tsvetkova et al., 2001; Nevinsky et al., 2001). After exhibiting tape, SSNTD was removed from the cylinder, cut on the sites corresponding to each day (length of 2 cm) and was exposed to standard chemical procedure. The number of tracks was considered in an optical microscope. 3. Results of measurement of radon with the help of the created device 3.1. Measurements in the mud volcanoes and in the caves Further, it was necessary to check up, how the new device works in real conditions. These two gauges have been
I. Nevinsky, T. Tsvetkova / Radiation Measurements 39 (2005) 115 – 119
117
Fig. 2. The map of Krasnodar territory. Points show places of measurement of soil radon. A—mud volcano “Miska” in Temruk. B—“Azishskaya” cave. I-2, II-1, II-2, II-3—places of simultaneous measurement of soil radon.
Temruk Azishskaya
2002-07_Rn-probe 30000 25000
Bq/m3
placed in the soil in “Azishskaya” cave and in the mud volcano “Miska” in Temruk (near Azov Sea). In these places, electronic semiconductor detectors already worked. The data from these gauges for geochemical tasks were used independently from each other. Fig. 2 shows a map of radon observation stations. Automatic devices with SSNTDs were placed close to the electronic detectors. In Fig. 3, as an example day-to-day changes of concentration of the soil radon received with the help of different detectors, is shown.
20000 15000 10000 5000 0 1
3
5
7
9
11 13 15 17 19 date
Temruk Azishskaya
2002-07_SSNTD
3.2. Simultaneous measurements of the several detectors on the large surface
21 23 25 27 29 31
25000
Bq/m3
20000
Since 2002, simultaneous measurements of the soil radon in the different items in the territory of Krasnodar region for a problem of the forecast of earthquakes are also begun. The distance between items is 50 km. In the points I-2, II-1, II2, II-3 (Fig. 2) automatic detectors with SSNTDs have been placed in the ground close to electronic scintillation detectors ZnS (Ag). Strip LR-115 varied every week. Changes of the average daily data, received from both kinds of detectors, coincided within the limits of mistakes. Thus, results which have been received with application of scintillation detectors have been confirmed. In Fig. 4, as an example, pictures of daily average concentration of soil radon in the territory of Krasnodar region, measured by data processing simultaneously from all detectors, are shown. Detectors are located in places of crossing
15000 10000 5000 0 1
3
5
7
9
11 13 15 17 19 21 23 25 27 29 31 date
Fig. 3. Changes of concentration of radon in the soil in the cave and in the mud volcano from day-to-day. The top figure shows the data of the electronic detector (Rn-probe). The bottom figure shows the data of the automatic detector with SSNTDs.
of vertical and horizontal lines. The data in figures resulted in relative units. The darker stain corresponds to high concentration of radon in the soil (up to 1200 Bq/m3 ).
118
I. Nevinsky, T. Tsvetkova / Radiation Measurements 39 (2005) 115 – 119 26.09.02
25.09.02 III
III
II
II
I 1
2
3
I 1
2
3
27.09.02
28.09.02
III
II
II
I 1
2
3
III
1
2
I 3
Fig. 4. Fields of different concentrations of radon in the soil (in relative units. Darker stain corresponds to higher concentration of radon) in territory of Krasnodar region on different days between September, 25, 2002, on September, 28, 2002. Crossings of direct lines of the maps correspond to places of accommodation of the gauges shown in Fig. 2. The big circle designates the place where the earthquake happened at 28.09.2002 in Abrau-Durso.
Accordingly, the lightest stain corresponds to the lowest concentration of radon (no more than 600 Bq/m3 ).
4. Discussion As shown in Fig. 3, changes of the average daily data from different kinds of detector of radon coincide within the limit of mistakes. As experiment, in the specified places, automatic detectors with SSNTD have been left only. It was revealed that the concentration of radon in the soil in the mud volcano “Miska” in Temruk strongly varies on a dayto-day basis. Strong rises and downturn of concentration of radon in a duration of 5–7 days were observed. After these strong changes which lasted some months the increased output of gas and water from gryphones was observed. On walls of the houses located near a volcano, there were cracks. Further concentration of radon went down sharply and was constantly low for a few months. In the “Azishskaya” cave, more stable data are observed. Measurements in the air of the cave with application of sedimentation of radon daughter nuclides on paper filters show its high concentration on the average 1300 Bq/m3 . However, strong deviations of concentration of radon in the air in this or that side are observed. Thus, there is a connection of Rn—concentration in the air of the cave with Rn—concentration in the soil. In Fig. 4, results show movement of the increased concentration of the soil radon in the Krasnodar territory on a day-to-day basis. The increased concentration of radon (dark stain) in the left part of the map on 25.09.2002 corresponds to the place of presence of mud volcanoes in Taman. Further moving the dark stain to item I-2 (settlement Abrau-Durso) within 4 days is observed. Abrau-Durso is designated in Fig. 4 by a circle. There was a local earthquake of average force on 28.09.2002. The increased concentration of radon again has returned on the following day to the condition similar as 25.09.2002. It is necessary to specify, that from September, 25th till September, 30th, essential changes of meteorological parameters were not observed. Similar movements of
high concentration of radon to the side where there was an earthquake, was repeatedly observed.
5. Conclusion In this article, very simple and cheap detector of soil radon on basis SSNTDs, working in an automatic mode, is described. The detector can be created by any person in any laboratory without special equipment. Any unqualified worker can make changes in SSNTDs. Only the clockwork in new detectors is a mechanical detail, therefore the detector practically is unique and does not spoil. Many hours are necessary to oil them once in a while. The Rn concentrations in many soils are such, that it is possible to obtain a statistically significant amount given every day. If it is necessary to raise sensitivity of the detector before SSNTD, the metal grid with a voltage of 700–800 V can be located. This voltage can be received from a very simple generator. Thus, the small battery can produce the necessary current within several months. Application of such a method shows increase in the number of tracks in a film some times due to increase of collection of daughter nuclides of radon. It will allow to obtain a statistically significant data at low concentration of radon in the soil air. Application of the described detectors in mud volcanoes helps to study laws in the change of their activity. The data from such detectors allow to supervise concentration of radon in the ground of a cave and to warn people working in excursion business of high concentration of radon in air of a cave. Simultaneous measurements of radon in the big area can be used for definition of the place of a probable earthquake. And for this purpose the simple and cheap detectors described can be used.
Acknowledgements We thank the Krasnodar Department of science and education for the financial support.
I. Nevinsky, T. Tsvetkova / Radiation Measurements 39 (2005) 115 – 119
References Monnin, M., Seidel, J., 1992. Radon in soil-air and in groundwater related to major geophysical events: a survey. Nucl. Instrum. Methods: Phys. Res. A 314, 316–330. Nevinsky, I., Nevinsky, V., Panyushkin, V., Ferronsky, V., Tsvetkova, T., 2001. An attempt to determine the tritium, 22 Na,
119
36 Cl and radon in territory of mud volcano in Taman. Radiat. Meas. 34, 349–353. Tsvetkova, T., Monnin, M., Nevinsky, I., Perelygin, V., 2001. Research on variation of radon and gamma-background as a prediction of earthquakes in the Caucasus. Radiat. Meas. 33, 1–5.