Cosmic Ray Ground Level Research Articles

Мониторинг околоземного космического пространства, магнитосферы и атмосферы Земли в периоды Форбуш-эффектов в конце августа 2005 г.

We present the results of near-Earth interplanetary space, magnetosphere, and atmosphere monitoring during large-scale solar wind disturbances at the end of August 2005. The monitoring was carried out using ground-level cosmic ray (CR) observations made at the worldwide network of neutron monitors as well as muon telescopes in Yakutsk and Novosibirsk. As a result of the analysis performed by different methods, we have obtained variation properties of CRs of different rigidities in Earth’s orbit, their pitch angle anisotropy, orientation and configuration of the interplanetary magnetic field, changes in the planetary system of geomagnetic cutoff rigidities during geomagnetic disturbances, as well as mass average air temperature over CR stations equipped with muon telescopes. For the periods of geomagnetic disturbances, we have determined parameters of magnetospheric ring current and magnetopause currents.

Monitoring of near-Earth space, Earth’s magnetosphere and atmosphere during Forbush decreases in August 2005

We present the results of near-Earth interplanetary space, magnetosphere, and atmosphere monitoring during large-scale solar wind disturbances at the end of August 2005. The monitoring was carried out using ground-level cosmic ray (CR) observations made at the worldwide network of neutron monitors as well as muon telescopes in Yakutsk and Novosibirsk. As a result of the analysis performed by different methods, we have obtained variation properties of CRs of different rigidities in Earth’s orbit, their pitch angle anisotropy, orientation and configuration of the interplanetary magnetic field, changes in the planetary system of geomagnetic cutoff rigidities during geomagnetic disturbances, as well as mass average air temperature over CR stations equipped with muon telescopes. For the periods of geomagnetic disturbances, we have determined parameters of magnetospheric ring current and magnetopause currents.

Monitoring of heliosphere, magnetosphere and atmosphere via cosmic ray effects in August 2018

Using data of ground-level cosmic ray measurements on the neutron monitor network, along with data of Yakutsk muon telescope complex and muon hodoscope URAGAN (Moscow) uncorrected for temperature, we used modified spectrographic global survey method for an August 2018 event to split cosmic ray variations into components of primary, magnetospheric and atmospheric origin. Time evolutions of isotropic primary flux for different rigidities, pitch-angle anisotropy of cosmic rays, interplanetary magnetic field orientation were obtained, variations in geomagnetic cut-off rigidity in Irkutsk and average-mass temperature over charged components’ measurement sites were also shown.

High Time-Resolution Readout Integrated Circuit Using DLL for Portable Cosmic Ray Muon Detection

Ground-level cosmic ray muon detections have various potential applications in the predictions of space and Earth weather variations and muon tomography. However, in order to push its practical applications, a low-power, low-cost, high-accuracy, and portable ground-level cosmic ray muon detection system needs to be developed. In this article, we present a high time-resolution and low-power readout integrated circuit (ROIC) for portable ground-level cosmic ray muon detection. The ROIC comprises preamplifiers, comparators, encoding modules, a delay-locked loop (DLL), and a data transfer module. The preamplifiers amplify the weak signals produced by the muon detector. The comparators convert the amplified signals into digital signals. The encoding modules extract and store the time information of the input pulses produced by the comparator, and the data transfer module transmits them to a microcontroller unit (MCU). A pulse edge detecting method using DLL clocks is employed to improve the time-resolution and limit the power consumption of the ROIC. A 32-channel prototype of the ROIC was designed and fabricated in a 0.18- μm mixed-signal CMOS process. The main chip size is 11.4 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . A one-channel double-layer plastic scintillator muon detector was used to test the performance of the ROIC. A time-resolution of 1.0 ns was achieved with a system clock of 50 MHz, and the ROIC power consumption was measured at 1.9 mW/channel. Compared with existing muon readout electronics systems, the system using the proposed ROIC achieves high time-resolution and accuracy, with low power consumption and a smaller size, making it suitable for portable real-time cosmic ray muon detection.

Improved Approach in the Coupling Function Between Primary and Ground Level Cosmic Ray Particles Based on Neutron Monitor Data

Improved Approach in the Coupling Function Between Primary and Ground Level Cosmic Ray Particles Based on Neutron Monitor Data

Effect of Some Solar Energetic Events on Cosmic Ray (CR) Ground Level Enhancement (GLE)

Ground Level Enhancements (GLEs) are sudden and short-lived increases in cosmic rays intensities registered by neutron monitors and usually associated with powerful solar explosive events. This work examines the key features of forty-nine (49) Ground level enhancement (GLE) events with a view to understanding the possible link to their solar sources. These constitute the 22nd -71st GLE as recorded by the Oulu Neutron monitor. We have computed the increase rates of the GLE and have compared them with the associated solar activity parameters. It is observed that GLEs are more associated with Solar flares than CMEs during the minimum and ascending phase of the 11 year solar cycle when compared with GLEs that occurred during the maximum phase of the solar cycle. In general, more GLE events were associated with solar flares originating from the Northern hemisphere of the solar disk as compared with the southern hemisphere flares. 80% of GLE with percentage increase rate (PIR) <10% were linked with strong flares. There was no/weak statistical association between intensity of solar energetic events (solar flares, CMEs, etc) and increase rate of GLE. The harder solar energetic fluxes seem to be responsible for GLEs with high PIR and that the softer fluxes may be responsible for those with low PIR. These results have important implications for our present understanding of potential solar drivers of the GLEs.

Angular Dependence Study of the Cosmic Ray Flux at 900 Meters Above Sea Level

In this study, the zenith angle distribution of the ground level cosmic ray flux have been measured at 900 meters above the sea level by using the developed prototype detector. The mea- surements have been done in Experimental Particle Physics Laboratory, Department of Physics, AIBU Bolu. The method used to carry out the experiment is by using simultaneous particle hits on two scintillator boxes that are arranged in tower mode then counts will accumulate in the scin- tillator counter boxes. This detector prototype provides a simpler, cheaper and suitable alternative to the common cosmic ray detectors for the detection of particles at ground level. The orientation of module is in the south-east direction. The fluxes and rates were measured for different zenith angles between 0o and 90o. The attenuation effect of the architectural components on the mea- sured cosmic ray flux was carried out by using GEANT4 simulation program and this effect was taken into account in the given results.

The Global Survey Method Applied to Ground-level Cosmic Ray Measurements

The global survey method (GSM) technique unites simultaneous ground-level observations of cosmic rays in different locations and allows us to obtain the main characteristics of cosmic-ray variations outside of the atmosphere and magnetosphere of Earth. This technique has been developed and applied in numerous studies over many years by the Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation (IZMIRAN). We here describe the IZMIRAN version of the GSM in detail. With this technique, the hourly data of the world-wide neutron-monitor network from July 1957 until December 2016 were processed, and further processing is enabled upon the receipt of new data. The result is a database of homogeneous and continuous hourly characteristics of the density variations (an isotropic part of the intensity) and the 3D vector of the cosmic-ray anisotropy. It includes all of the effects that could be identified in galactic cosmic-ray variations that were caused by large-scale disturbances of the interplanetary medium in more than 50 years. These results in turn became the basis for a database on Forbush effects and interplanetary disturbances. This database allows correlating various space-environment parameters (the characteristics of the Sun, the solar wind, et cetera) with cosmic-ray parameters and studying their interrelations. We also present features of the coupling coefficients for different neutron monitors that enable us to make a connection from ground-level measurements to primary cosmic-ray variations outside the atmosphere and the magnetosphere. We discuss the strengths and weaknesses of the current version of the GSM as well as further possible developments and improvements. The method developed allows us to minimize the problems of the neutron-monitor network, which are typical for experimental physics, and to considerably enhance its advantages.

Study of heliospheric disturbances on the basis of cosmic ray muon flux anisotropy

The features of the study of heliospheric disturbances on the basis of ground level cosmic ray muon flux observations are discussed. The muon hodoscope URAGAN simultaneously detects muons from various directions of the celestial hemisphere. This allows us to analyze spatial-angular variations of muon flux during such events. Heliospheric disturbances that caused the changes of interplanetary magnetic field parameters measured by various space vehicles are considered. A special attention is paid to the analysis of the response of the muon hodoscope URAGAN for recent most powerful solar flares that occurred in March 2012. In accordance with the results of the study, methods of separating main heliospheric disturbances are proposed. The prognostic potential of the developed approaches to the study of heliospheric disturbances by means of the penetrating component of cosmic rays is evaluated.

Forbush-decreases in 19th solar cycle

The abnormally high solar activity was observed in the late 50's – the early 60's of the 20th century, but not many possibilities was available that time of its observation to which we have got in use during the last years. Ground level cosmic ray observations, along with geomagnetic activity, are one of a few kinds of the continuous measurements, allowing to judge on the events of 19th cycle. The IZMIRAN Database in which all Forbush-decreases are collected since July, 1957 has been used for the analysis. To make the statistics of 19th cycle fuller, the catalogue by Lockwood containing rather big Forbush-decreases (>3 %), picked out from the data of one neutron monitor (Mount Washington), was involved. Comparison of the events in cosmic rays with solar and geomagnetic activity has shown that the quantity and intensity of geomagnetic storms in 19th cycle correspond to abnormally high number of the sunspots. However in this cycle there is a certain deficiency of Forbush-effects of the large size. Apparently, deficiency of the big Forbush-decreases during this period means that coronal mass ejections (CMEs/ICMEs) in the 19th cycle distinguished from later CMEs and differently affected of the cosmic ray modulation and geomagnetic activity. Probably, the most powerful CMEs of the 19th cycle had, as a whole, the smaller size, than the greatest emissions of solar plasma in later period.

The extreme solar cosmic ray particle event on 20 January 2005 and its influence on the radiation dose rate at aircraft altitude

In January 2005 toward the end of solar activity cycle 23 the Sun was very active. Between 15 and 20 January 2005, the solar active region NOAA AR 10720 produced five powerful solar flares. In association with this major solar activity several pronounced variations in the ground-level cosmic ray intensity were observed. The fifth of these flares (X7.1) produced energetic solar cosmic rays that caused a giant increase in the count rates of the ground-based cosmic ray detectors (neutron monitors). At southern polar neutron monitor stations the increase of the count rate reached several thousand percent. From the recordings of the worldwide network of neutron monitors, we determined the characteristics of the solar particle flux near Earth. In the initial phase of the event, the solar cosmic ray flux near Earth was extremely anisotropic. The energy spectrum of the solar cosmic rays was fairly soft during the main and the decay phase. We investigated also the flux of different secondary particle species in the atmosphere and the radiation dosage at flight altitude. Our analysis shows a maximum increment of the effective dose rate due to solar cosmic rays in the south polar region around 70°S and 130°E at flight altitude of almost three orders of magnitude.

GLEs as a Warning Tool for Radiation Effects on Electronics and Systems: A New Alert System Based on Real-Time Neutron Monitors

Ground level cosmic ray enhancements (GLEs) are the manifestations of short-time solar energetic particles radiation near the Earth causing damage to electronic devices carried on board the satellite platforms. A test alert system based on a real-time ground-level neutron monitor network is proposed in order to protect devices and electronics from space weather radiation effects.

Radiation dose along North American transcontinental flight paths during quiescent and disturbed geomagnetic conditions

Commercial aircraft flights across the North American continent encounter a small radiation exposure (normally &lt;20 μSv) from galactic cosmic radiation. During October and November 2003, there was significant perturbation in the cosmic ray flux near the Earth due to extraordinary activity on the Sun. The associated sequence of solar flares and coronal mass ejections resulted in a significant decrease in the background galactic cosmic radiation levels upon which there were sudden impulsive increases from solar cosmic ray events. These fluctuations in the cosmic ray intensity were detectable at commercial aircraft cruising altitudes and at sea level cosmic ray neutron‐monitoring stations. This paper compares the in‐flight radiation dose data acquired during the disturbed conditions on 29 October 2003 with the dose data acquired over the same route in January 2004 during quiescent geomagnetic conditions. This comparison shows that during Forbush decreases or ground level cosmic ray increases, the CARI aircraft radiation dose prediction software does not adequately describe the radiation exposure from cosmic radiation.

Initial concept for forecasting the flux and energy spectrum of energetic particles using ground-level cosmic ray observations

We describe the principles and operation of automated programs “FEP-Research-1st Alert”, “FEP-Research-2nd Alert”, and “FEP-Research-3rd Alert”. The program “FEP-Research-lst Alert” gives preliminary determinations of the energy spectrum and flux at the beginning of an event on the basis of 1-minute data of total neutron intensity and intensities of different multiplicities in the neutron monitor (NM) at the Emilio Segre' Observatory (2025m above sea level, Rc = 10.8 GV) as well as available 1-minute on-line data in the near future of Cosmic Ray Observatories which collaborate with the Israel Cosmic Ray Center (Rome, Haleakala, Climax, Oulu, Moscow, Apatity, Mexico, Aragaz and others). Using well-known coupling functions for neutron monitors we have derived functions that relate the spectral index of flare energetic particles (FEP) to observations of multiplicities. We also derived important functions using ratios of FEP observations from the different cosmic ray monitors mentioned above. All these functions are approximated analytically with good accuracy and can be used for automatic realtime determination of the energy spectrum and fluxes of FEP. Using approximate values of the diffusion coefficient for the current level of solar activity as a function of particle energy, the program “FEP-Research-1st Alert” determines very roughly the expected level of radiation in space after 1 2 , 1, 3 2 and 2 hours. If this level is expected to be dangerous for satellites and spacecrafts, the program “FEP- Research-1st Alert” sends preliminary 1st Alert. More accurate forecasts are given after 5–10 minutes by the program “FEP-Research-2nd Alert”, and after 10–20 minutes program by the “FEP-Research-3rd Alert” using information on the diffusion coefficient obtained from on-line FEP ground data.

Aspects of combining models of the Earth's internal and external magnetic field.

On the basis of an analysis of the 7/8 December 1982 ground-level cosmic ray event the paper specifies the limitations of any mathematical model of the main geomagnetic field in its use for cosmic ray analyses, presents procedures and problems of combining models of the Earth's internal field with models of the external geomagnetic field, and discusses the significance of the external geomagnetic field for calculations of cosmic ray particle trajectories in near-Earth space.

７．５ｃｍφ球形ＮａＩ（Ｔｌ）シンチレーション検出器による地上レベルにおける５ＭｅＶ以下の宇宙線波高分布スペクトル

Ground level cosmic ray pulse height spectrum of a 7.5cm diameter spherical NaI (T1) scintillation detector was evaluated through stripping operation based on a pulse height spectrum measured on the sea and high precision response functions of the detector for U-series, Th-series and 40K. The exposure rate calculated from the determined cosmic ray pulse height spectrum was 0.21μR/h eq., which agreed well with that obtained from another method. The shape of the pulse height spectrum showed similarity to that measured at the altitude of 16, 000 ft, especially in the energy region of 0 to 3MeV. The principle of the adopted method is rather plain, however, the reliability of the spectrum is satisfactory. As the pulse height spectrum is a common information to any analytical method for environmental gamma ray using NaI (T1) scintillation detector, it is expected to be used for simple and precise separation of cosmic ray component involved in the enviromental pulse height spectrum.

The Cosmic Ray Solar Flare Increase of 16 February 1984

Six solar proton events have been observed by ground level cosmic ray detectors so far during solar cycle 21, a little less than one per year. All of these have been much smaller than the giant events observed in solar cycle 19. As with many other aspects of solar activity, the reason for the differences from cycle to cycle remain unknown.

Ground Level Cosmic Ray Energy Spectrum in the Energy Range 0 to 4 MeV - Observed with a Spherical NaI(Tl) Spectrometer

Ground Level Cosmic Ray Energy Spectrum in the Energy Range 0 to 4 MeV - Observed with a Spherical NaI(Tl) Spectrometer

Inference of sector polarity of the inter-planetary magnetic field from the cosmic ray north-south asymmetry

The sector polarity of the interplanetary magnetic field has been inferred daily for the period 1971–1973, using ground level cosmic ray observations. The method depends on the sectors directed towards and away from the Sun being associated with different characteristic variations of the cosmic ray north-south asymmetry. The analysis has a simple basis. The difference between the north and south daily mean intensities of directional telescopes at a single observing station is determined and its value relative to the 27-day average is calculated. The sign (negative or positive) of the value thus derived corresponds to the sector polarity on a daily basis. Good (~76%) agreement is obtained between the polarities inferred indirectly by the present method and those observed directly with the spacecraft magnetometers. We therefore suggest that cosmic ray observations can be used for inferring the sector polarity of the magnetic field in interplanetary space.

A comparison of ground level cosmic ray enhancements of November 22, 1977 and February 25, 1969

The anisotropic solar flare increases observed by neutron monitors on November 22, 1977 and February 25, 1969 are discussed. These events occurred at quite different modulation levels of galactic cosmic rays. The characteristics of the events such as anisotropy, rise and decay times are not significantly different from one event to the other. This implies that the interplanetary conditions for propagation of cosmic rays of a few GeV (109 eV) energy are comparable at the sunspot maximum and minimum of solar cycle 20. Therefore, the near‐earth environment does not play a major role in the modulation of galactic cosmic ray intensity and the cause of its 11‐year variation has to be sought in the regions off the ecliptic plane and/or farther out in the ecliptic plane.