A Study on Diurnal Variation of Cosmic Ray Flux using Daejeon and Jang Bogo Neutron Monitors

The cosmic-ray diurnal variation has been observed with scintillator telescopes at a depth of 40 m.w.e. at Chacaltaya, Bolivia, since the last solar maximum, and at the same depth near Albuquerque, New Mexico, since the last solar minimum. During the solar maximum from 1958 to 1960 the amplitude of the diurnal variation was 0.3% for the Chacaltaya telescopes, but at solar minimum early in 1965 it was as low as 0.05%. Since that time, the amplitude has been steadily increasing, and it is now between 0.1% and 0.2% at both the Bolivia and the New Mexico stations.The telescopes measure the cosmic-ray flux from the north, south, east, and west directions, as well as from the vertical; and the various observed times of the diurnal maximum for these directions confirm the extraterrestrial nature of the anisotropy. The maximum occurs at approximately 15 h local solar time in the vertical telescopes. A study of the asymptotic directions of these telescopes for differing primary energies, and of the behavior of the phases of the diurnal variation at the two stations, gives indications of the energies of the primary particles responsible for the diurnal variation. The results are compared with the models of Axford and of Ahluwalia and Dessler.

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On the nature of some anomalies in the cosmic-ray distribution

Canadian Journal of Physics ◽

10.1139/p68-308 ◽

1968 ◽

Vol 46 (10) ◽

pp. S614-S616 ◽

Cited By ~ 1

Author(s):

N. P. Chirkov ◽

G. F. Krymsky ◽

A. I. Kuzmin

Keyword(s):

Magnetic Field ◽

Diurnal Variation ◽

Interplanetary Magnetic Field ◽

Equatorial Plane ◽

Geomagnetic Field ◽

Cosmic Ray ◽

Neutron Monitors ◽

Vector Method ◽

Worldwide Network ◽

Northern And Southern Hemispheres

Diurnal and semidiurnal variations of the data from the worldwide network of neutron monitors during 1958 are analyzed using the receiving-vector method. It is shown that there exists an "antisymmetric" diurnal variation, i.e., a variation with opposite phases in the northern and southern hemispheres. After correction for the distortion due to the geomagnetic field, it is found that this variation has an amplitude of 0.03% and an hour of maximum at 21.5 hours in the northern hemisphere. If the variation is due to cosmic-ray screening in the interplanetary magnetic field, this field must have a slope of 7° with respect to the solar equatorial plane.

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The Upper Limiting Primary Rigidity of the Cosmic Ray Solar Anisotropy

Australian Journal of Physics ◽

10.1071/ph650451 ◽

1965 ◽

Vol 18 (5) ◽

pp. 451 ◽

Cited By ~ 7

Author(s):

RM Jacklyn ◽

JE Humble

Keyword(s):

Diurnal Variation ◽

Sea Level ◽

Free Space ◽

Daily Variation ◽

Cosmic Ray ◽

Neutron Monitors ◽

Annual Average ◽

Average Value

A method of determining the upper limiting rigidity of the solar diurnal variation of the cosmic ray primaries in free space is described. It involves a comparision of the response to the anisotropy of neutron monitors at sea level and of meson telescopes underground. Making use of the model for the free-space first harmonic proposed by Radio, McCracken, and Venkatesan, the annual average value for the upper limiting rigidity (Ru) in 1958 is estimated to have been 95 GV with an error of estimate of about 10-20 GV. Changes in the observed annual mean daily variation between 1958 and 1962 indicate that Ru may have decreased by about 20-40 GV over this period, but a more refined analysis is needed to confirm this.

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Decadal trends in the diurnal variation of galactic cosmic rays observed using neutron monitor data

Annales Geophysicae ◽

10.5194/angeo-35-825-2017 ◽

2017 ◽

Vol 35 (4) ◽

pp. 825-838 ◽

Cited By ~ 2

Author(s):

Simon Thomas ◽

Mathew Owens ◽

Mike Lockwood ◽

Chris Owen

Keyword(s):

Phase Change ◽

Diurnal Variation ◽

Neutron Monitor ◽

Cosmic Ray ◽

Galactic Cosmic Rays ◽

Energetic Particles ◽

Magnetic Polarity ◽

Neutron Monitors ◽

Neutron Monitor Data ◽

Monitor Data

Abstract. The diurnal variation (DV) in galactic cosmic ray (GCR) flux is a widely observed phenomenon in neutron monitor data. The background variation considered primarily in this study is due to the balance between the convection of energetic particles away from the Sun and the inward diffusion of energetic particles along magnetic field lines. However, there are also times of enhanced DV following geomagnetic disturbances caused by coronal mass ejections or corotating interaction regions. In this study we investigate changes in the DV over four solar cycles using ground-based neutron monitors at different magnetic latitudes and longitudes at Earth. We divide all of the hourly neutron monitor data into magnetic polarity cycles to investigate cycle-to-cycle variations in the phase and amplitude of the DV. The results show, in general, a similarity between each of the A < 0 cycles and A > 0 cycles, but with a phase change between the two. To investigate this further, we split the neutron monitor data by solar magnetic polarity between times when the dominant polarity was either directed outward (positive) or inward (negative) at the northern solar pole. We find that the maxima and minima of the DV changes by, typically, 1–2 h between the two polarity states for all non-polar neutron monitors. This difference between cycles becomes even larger in amplitude and phase with the removal of periods with enhanced DV caused by solar wind transients. The time difference between polarity cycles is found to vary in a 22-year cycle for both the maximum and minimum times of the DV. The times of the maximum and minimum in the DV do not always vary in the same manner between A > 0 and A < 0 polarity cycles, suggesting a slight change in the anisotropy vector of GCRs arriving at Earth between polarity cycles. Polar neutron monitors show differences in phase between polarity cycles which have asymptotic directions at mid-to-high latitudes. All neutron monitors show changes in the amplitude of the DV with solar polarity, with the amplitude of the DV being a factor of 2 greater in A < 0 cycles than A > 0 cycles. In most cases the change in timing of the maximum /minimum is greatest with the stations' geomagnetic cut-off rigidity shows little variation in the DV phase with latitude. We conclude that the change in the DV with the dominant solar polar polarity is not as simple as a phase change, but rather an asymmetric variation which is sensitive to the neutron monitor's asymptotic viewing direction.

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Characteristics of Cosmic Ray Diurnal Variation from Deep River Neutron and Meson Data and Temperature Effects

Canadian Journal of Physics ◽

10.1139/p72-181 ◽

1972 ◽

Vol 50 (12) ◽

pp. 1323-1331 ◽

Cited By ~ 2

Author(s):

S. P. Agrawal ◽

A. G. Ananth ◽

U. R. Rao

Keyword(s):

Solar Cycle ◽

Diurnal Variation ◽

Temperature Effects ◽

Cosmic Ray ◽

Cutoff Rigidity ◽

Neutron Data ◽

Neutron Monitors ◽

Temperature Coefficients ◽

Extensive Analysis ◽

Yield Values

From an extensive analysis of Deep River meson data for over 5 years, new temperature coefficients have been derived for correcting the meson data. It is shown that meson data corrected using new coefficients yield values of diurnal and semidiurnal anisotropy consistent with those obtained from neutron monitors. Using the temperature-corrected meson and neutron data, the upper cutoff rigidity beyond which the diurnal variation ceases is shown to vary with solar cycle showing a minimum of about 35 GV during the Quiet Solar Year of 1965, and a maximum of ≈ 125 GV during 1968–1969.

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Cosmic ray sidereal diurnal variation of galactic origin observed by neutron monitors

Planetary and Space Science ◽

10.1016/0032-0633(83)90064-8 ◽

1983 ◽

Vol 31 (11) ◽

pp. 1269-1278 ◽

Cited By ~ 12

Author(s):

K. Nagashima ◽

Y. Ishida ◽

S. Mori ◽

I. Morishita

Keyword(s):

Diurnal Variation ◽

Cosmic Ray ◽

Neutron Monitors

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The mini-neutron monitor: a new approach in neutron monitor design

Journal of Space Weather and Space Climate ◽

10.1051/swsc/2020038 ◽

2020 ◽

Vol 10 ◽

pp. 39

Author(s):

Du Toit Strauss ◽

Stepan Poluianov ◽

Cobus van der Merwe ◽

Hendrik Krüger ◽

Corrie Diedericks ◽

...

Keyword(s):

Neutron Monitor ◽

Radiation Risk ◽

Cosmic Ray ◽

Cost Effective ◽

Space Travel ◽

Neutron Monitors ◽

New Approach ◽

Effective Version ◽

Technical Details ◽

Cosmic Ray Flux

The near-Earth cosmic ray flux has been monitored for more than 70 years by a network of ground-based neutron monitors (NMs). With the ever-increasing importance of quantifying the radiation risk and effects of cosmic rays for, e.g., air and space-travel, it is essential to continue operating the existing NM stations, while expanding this crucial network. In this paper, we discuss a smaller and cost-effective version of the traditional NM, the mini-NM. These monitors can be deployed with ease, even to extremely remote locations, where they operate in a semi-autonomous fashion. We believe that the mini-NM, therefore, offers the opportunity to increase the sensitivity and expand the coverage of the existing NM network, making this network more suitable to near-real-time monitoring for space weather applications. In this paper, we present the technical details of the mini-NM’s design and operation, and present a summary of the initial tests and science results.

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On the character of cosmic ray variations at f>2x10<SUP>-5</SUP> Hz

Nonlinear Processes in Geophysics ◽

10.5194/npg-3-135-1996 ◽

1996 ◽

Vol 3 (2) ◽

pp. 135-141 ◽

Cited By ~ 3

Author(s):

K. Kudela ◽

E. O. Flückiger ◽

J. Torsti ◽

H. Debrunner

Keyword(s):

Magnetic Field ◽

Time Series ◽

Diurnal Variation ◽

White Noise ◽

Interplanetary Magnetic Field ◽

Time Scales ◽

Cosmic Ray ◽

Neutron Monitors ◽

Scaling Properties ◽

Interplanetary Disturbance

Abstract. We examine the time series of cosmic ray (CR) intensity recorded by two neutron monitors (NMs) at medium latitudes for scaling properties on time scales shorter than the diurnal variation. Scaling of the data with 10 sec as well as I min resolution is shown to be complicated, indicating that there is probably not a unique process governing the CR fluctuations in the whole interval studied. For T < 20 min the general characteristics are similar to those of white noise. Above 40-60 min the scaling characteristics are dependent on the level of interplanetary disturbance. This is consistent with the concept of scattering CRs by inhomogeneities of the interplanetary magnetic field (IMF). With increasing interplanetary turbulence the dimensionality of the CR time series decreases. The region of stable scaling is, however, narrow, only up to 6 hours. Multifractality signatures in the region 1-6 hours are similar to those in the IMF, however the deviations from monofractality are relatively small.

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Estimation of the state of the cosmic ray flux based on neural networks

E3S Web of Conferences ◽

10.1051/e3sconf/202019601007 ◽

2020 ◽

Vol 196 ◽

pp. 01007

Author(s):

Bogdana Mandrikova ◽

Alexei Dmitriev

Keyword(s):

Neural Network ◽

Neural Networks ◽

A Priori ◽

Cosmic Ray ◽

The State ◽

Neutron Monitors ◽

Automated Method ◽

The Neural Network ◽

On Line ◽

Cosmic Ray Flux

An automated method is proposed for assessing the state of the cosmic ray flux on the base of neural networks. The method allows using the data of neutron monitors to determine the state of the cosmic ray flux in accordance with the a priori specified states of the neural network. The paper evaluates the method and presents the results of its application during periods of increased solar activity and magnetic storms. The possibility of realizing the method on-line is demonstrated.

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Small-scale cosmic-ray fluctuations and their association with recurrent phenomena, October 1965 through April 1966

Canadian Journal of Physics ◽

10.1139/p68-370 ◽

1968 ◽

Vol 46 (10) ◽

pp. S866-S870 ◽

Cited By ~ 1

Author(s):

F. Bachelet ◽

E. Dyring ◽

N. Iucci ◽

G. Villoresi

Keyword(s):

Power Spectrum ◽

Diurnal Variation ◽

Spectrum Analysis ◽

High Latitude ◽

Cosmic Ray ◽

Power Spectrum Analysis ◽

Small Scale ◽

High Latitudes ◽

Neutron Monitors

A method is developed for separating the diurnal variation from cosmic-ray data recorded by NM64 neutron monitors at high latitudes. It utilizes the negligible diurnal variation at the Alert station, which is verified by power spectrum analysis. The method offers the development of a "universal high-latitude diurnal wave" on a day-to-day basis, taking into account the asymptotic longitude differences between the stations.The period 15 October 1965 to 30 April 1966 is studied in connection with the space measurements of Pioneer VI.

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