1:45 PM - 3:15 PM
[O08-P15] Correlation and periodicity between the relative number of sunspots and the number of cosmic ray detections
Keywords:cosmic ray, sunspot, solar activity
1. Motivation and purpose
Our school has been observing sunspots since the 15cm refractor telescope was installed in 1970.However, sunspot observation data have never been used for research. We began our research based on the hypothesis that there is a correlation between the number of sunspots, which increases with solar activity, and the number of cosmic rays arriving on Earth, and that the frequency of cosmic ray arrivals changes with the solar activity cycle.
2. What are cosmic rays?
Cosmic rays are subatomic particles moving at nearly the speed of light, interacting with atoms in the atmosphere to produce multiple particles from their energy, which then fall to the earth's surface in the form of large numbers of particles like showers.There are two types of cosmic rays: relatively low-energy solar cosmic rays from the sun and galactic cosmic rays from outside the solar system.
3. Methods
3-1. Methods of Observing Cosmic Rays
Cosmic rays were constantly observed using the cosmic ray detector "cosmic watch" to collect information on the transit time and energy of cosmic rays, and observations were made from November 2020 to May 2021 using a single cosmic watch unit.Unprocessed is data A.The data removed by considering the values below adc200 as noise are Data B, and Data C is the data narrowed down to only the daytime (06:00 to 18:00) when the sun is out after the values below adc 200 are deleted.
In addition, two cosmic watches were installed on top of each other to reduce noise, and a two-watch observation was conducted from June to December 2021, focusing only on cosmic rays observed by the two watches.The unprocessed data are Data D, and those focused on daytime cosmic rays are Data E.No noise is assumed to be included in the two-unit observation, and no adc cut is performed.
3-2. Sunspot Observation Methods
Sunspots were recorded on sketch paper using the school's 15cm refractor telescope.The relative number of sunspots R = k(10g+f) is then obtained by assuming that the number of sunspots is f, the number of sunspot groups is g, and the correction factor k = 1. The relative sunspot counts aggregated by WDC-SILSO of the Royal Observatory of Belgium were also used in the study.
3-3. Analysis
3-3-1. Correlation between cosmic rays and relative sunspot number
The number of detections per second for data A, B, C, D, and E were determined and the correlation coefficients between the relative number of sunspots in this school and the relative number of sunspots in WDC-SILSO were examined.The correlation coefficients between the cosmic ray data and the relative number of each sunspot, divided by adc100 as adc0-100, 100-200..., respectively.
3-3-2 .Periodicity of arrival frequency of cosmic rays
To confirm the period of arrival frequency of cosmic rays, Fourier transforms were performed on the data from one and two observation units, respectively.
4. Results and Discussion
4-1. Correlation between cosmic rays and relative sunspot number
The correlation between cosmic rays and the relative number of sunspots is shown in Fig1.Although the correlations between Iwata-Minami and WDC-SILSO are different, similar trends are observed from Data A to D. Data B and C are both negatively correlated.The correlation coefficients between Data D and E and the relative number of sunspots ( Iwata-Minami ) are small because of the small number of sunspot data in Iwata-Minami during the period when two units were observing.
Graphs 1,2 show the correlation coefficients when the cosmic ray data is divided by adc100.The correlation coefficients between the two observation data and the relative number of sunspots (WDC-SILSO) were negative below adc400 and positive above adc400, with the positive and negative correlation coefficients reversing after adc400.Cosmic rays below adc400 are considered to be solar cosmic rays. The results with the relative sunspot number (Iwata South) differed significantly from the results with the relative sunspot number (WDC-SILSO) due to the lack of sunspot data. On the other hand, there was no trend in the correlation coefficient for the data from a single observation.
These results indicate that the number of cosmic ray arrivals decreases as solar activity increases.
4-2. Periodicity of arrival frequency of cosmic rays
Both single and dual observation data showed 12-hour and 24-hour cycles. (Graphs 3,4) Both periods are related to the diurnal motion of the sun.
5. Conclusion
There is a negative correlation between the relative number of sunspots and the number of cosmic ray arrivals.The arrival frequency of cosmic rays has a 12-hour and 24-hour cycle, which is thought to be related to the diurnal motion of the sun.
Our school has been observing sunspots since the 15cm refractor telescope was installed in 1970.However, sunspot observation data have never been used for research. We began our research based on the hypothesis that there is a correlation between the number of sunspots, which increases with solar activity, and the number of cosmic rays arriving on Earth, and that the frequency of cosmic ray arrivals changes with the solar activity cycle.
2. What are cosmic rays?
Cosmic rays are subatomic particles moving at nearly the speed of light, interacting with atoms in the atmosphere to produce multiple particles from their energy, which then fall to the earth's surface in the form of large numbers of particles like showers.There are two types of cosmic rays: relatively low-energy solar cosmic rays from the sun and galactic cosmic rays from outside the solar system.
3. Methods
3-1. Methods of Observing Cosmic Rays
Cosmic rays were constantly observed using the cosmic ray detector "cosmic watch" to collect information on the transit time and energy of cosmic rays, and observations were made from November 2020 to May 2021 using a single cosmic watch unit.Unprocessed is data A.The data removed by considering the values below adc200 as noise are Data B, and Data C is the data narrowed down to only the daytime (06:00 to 18:00) when the sun is out after the values below adc 200 are deleted.
In addition, two cosmic watches were installed on top of each other to reduce noise, and a two-watch observation was conducted from June to December 2021, focusing only on cosmic rays observed by the two watches.The unprocessed data are Data D, and those focused on daytime cosmic rays are Data E.No noise is assumed to be included in the two-unit observation, and no adc cut is performed.
3-2. Sunspot Observation Methods
Sunspots were recorded on sketch paper using the school's 15cm refractor telescope.The relative number of sunspots R = k(10g+f) is then obtained by assuming that the number of sunspots is f, the number of sunspot groups is g, and the correction factor k = 1. The relative sunspot counts aggregated by WDC-SILSO of the Royal Observatory of Belgium were also used in the study.
3-3. Analysis
3-3-1. Correlation between cosmic rays and relative sunspot number
The number of detections per second for data A, B, C, D, and E were determined and the correlation coefficients between the relative number of sunspots in this school and the relative number of sunspots in WDC-SILSO were examined.The correlation coefficients between the cosmic ray data and the relative number of each sunspot, divided by adc100 as adc0-100, 100-200..., respectively.
3-3-2 .Periodicity of arrival frequency of cosmic rays
To confirm the period of arrival frequency of cosmic rays, Fourier transforms were performed on the data from one and two observation units, respectively.
4. Results and Discussion
4-1. Correlation between cosmic rays and relative sunspot number
The correlation between cosmic rays and the relative number of sunspots is shown in Fig1.Although the correlations between Iwata-Minami and WDC-SILSO are different, similar trends are observed from Data A to D. Data B and C are both negatively correlated.The correlation coefficients between Data D and E and the relative number of sunspots ( Iwata-Minami ) are small because of the small number of sunspot data in Iwata-Minami during the period when two units were observing.
Graphs 1,2 show the correlation coefficients when the cosmic ray data is divided by adc100.The correlation coefficients between the two observation data and the relative number of sunspots (WDC-SILSO) were negative below adc400 and positive above adc400, with the positive and negative correlation coefficients reversing after adc400.Cosmic rays below adc400 are considered to be solar cosmic rays. The results with the relative sunspot number (Iwata South) differed significantly from the results with the relative sunspot number (WDC-SILSO) due to the lack of sunspot data. On the other hand, there was no trend in the correlation coefficient for the data from a single observation.
These results indicate that the number of cosmic ray arrivals decreases as solar activity increases.
4-2. Periodicity of arrival frequency of cosmic rays
Both single and dual observation data showed 12-hour and 24-hour cycles. (Graphs 3,4) Both periods are related to the diurnal motion of the sun.
5. Conclusion
There is a negative correlation between the relative number of sunspots and the number of cosmic ray arrivals.The arrival frequency of cosmic rays has a 12-hour and 24-hour cycle, which is thought to be related to the diurnal motion of the sun.