A study of daily variation in cosmic ray intensity during high/low amplitude days

Pramana ◽  
2007 ◽  
Vol 68 (3) ◽  
pp. 407-422 ◽  
Author(s):  
Rajesh K Mishra ◽  
Rekha Agarwal Mishra
Keyword(s):  
Daily Variation ◽  
Cosmic Ray ◽  
Cosmic Ray Intensity ◽  
Low Amplitude

scholarly journals 40. Separation of extra terrestrial variations in cosmic ray intensity and atmospheric effects by differential measurements by G–M telescopes

1958 ◽  
Vol 6 ◽  
pp. 386-391
Author(s):  
E. A. Brunberg
Keyword(s):  
Daily Variation ◽  
Cosmic Ray ◽  
The Other ◽  
Atmospheric Effects ◽  
Cosmic Ray Intensity ◽  
Difference Of Opinion

The daily variation of cosmic ray intensity can arise partly from atmospheric and partly from non-atmospheric effects. There is at present a difference of opinion whether this latter effect is completely due to extra terrestrial causes or not.The purpose of the present paper is to suggest a method by which the atmospheric effects could be separated from the other variations without any assumptions about the mechanism of the atmospheric influence.

Unusually low-amplitude anisotropic wave-train events of cosmic ray intensity during 1981–1994

Pramana ◽  
2005 ◽  
Vol 64 (2) ◽  
pp. 197-206
Author(s):  
Rajesh K. Mishra ◽  
Rekha Agarwal Mishra
Keyword(s):  
Wave Train ◽  
Cosmic Ray ◽  
Cosmic Ray Intensity ◽  
Low Amplitude

Time variations of directional cosmic ray intensity at low latitude - II. Time variations of east-west asymmetry

1961 ◽  
Vol 263 (1312) ◽  
pp. 118-126 ◽  
Keyword(s):  
Geomagnetic Storms ◽  
Daily Variation ◽  
Cosmic Ray ◽  
Middle Latitude ◽  
Geomagnetic Disturbance ◽  
Equatorial Station ◽  
Cosmic Ray Intensity ◽  
Primary Cosmic Radiation ◽  
Time Variations ◽  
East West

Changes of the energy spectrum of primary cosmic radiation can be followed through the time variations of east-west asymmetry of the μ -meson component at low latitudes. Such a study has been conducted for the first time at Ahmedabad during 1957-8. The changes of east-west asymmetry are associated with changes of the daily variation of cosmic ray in­tensity, of the daily mean neutron intensity measured at equatorial and middle latitude stations, of the index of geomagnetic disturbance and of the horizontal component of the earth’s magnetic field. The study indicates that days with high east-west asymmetry are associated with geomagnetically quiet days and a cosmic ray daily variation consistent with its being produced by an anisotropy of primary radiation outside the influence of the geomagnetic field. On such days, the daily variation produced by the anisotropy, as observed at an equatorial station, has a significant diurnal as well as a semi-diurnal component. High east-west asymmetry and associated anisotropy occur 3 to 5 days before the arrival of solar corpuscular beams which envelop the earth. Days with low east-west asymmetry occur about 3 to 4 days after the onset of cosmic ray storms associated with geomagnetic storms, usually of the SC type.

Daily variation of cosmic rays during quiet and disturbed periods in 1965 and 1966

1968 ◽  
Vol 46 (10) ◽  
pp. S819-S822
Author(s):  
Pekka J. Tanskanen
Keyword(s):  
Daily Variation ◽  
Cosmic Ray ◽  
Ecliptic Plane ◽  
Neutron Monitors ◽  
Monthly Basis ◽  
Cosmic Ray Intensity ◽  
Variable Amplitude ◽  
Ecliptic Latitude ◽  
Streaming Velocity ◽  
Corrected Data

Data from super neutron monitors at Deep River, Churchill, Resolute, and Alert have been used to study the daily variation of cosmic-ray intensity during 1965 and 1966. Intensities have been examined on a daily, weekly, and monthly basis as a function of the asymptotic direction of vertically incident 7.5-BeV particles. The data have been analyzed in an earth-centered solar-ecliptic coordinate system in which daily (due to the earth's rotation) and seasonal (due to the inclination of the earth's axis to the ecliptic plane) variations of the asymptotic directions are considered.During undisturbed periods the daily variation has been examined by applying a digital filter to the pressure-corrected data and also to the data after subtraction of a variable-amplitude Parker–Axford theoretical diurnal variation. Particular attention has been paid to the dependence of the observed daily variation on the solar-ecliptic latitude of the asymptotic direction.Seventy-three percent of the weeks considered in 1965 and 1966 give the phase of the first harmonic in a direction 85° ± 35 °E. Sixty percent of the weekly periods show a daily variation as a function of solar-ecliptic latitude which is in agreement with the Parker–Axford "streaming-velocity" theory. During Forbush decreases the diurnal phase shifts towards earlier hours and the amplitude increases to two to three times the predecrease level.

Time variations of directional cosmic ray intensity at low latitudes: I. Comparison of daily variation of the intensity of cosmic rays incident from east and west

1961 ◽  
Vol 263 (1312) ◽  
pp. 101-117 ◽  
Keyword(s):  
Geomagnetic Field ◽  
Daily Variation ◽  
Cosmic Ray ◽  
Local Source ◽  
Cosmic Ray Intensity ◽  
Low Latitudes ◽  
Long Term Changes ◽  
Time Variations ◽  
East And West

A study has been, conducted at Ahmedabad during 1957 and 1958 of the time variations of meson intensity incident from east and west at 45° to the vertical. A characteristic differ­ence of about 6 h in the diurnal time of maximum for the east and west directions is observed to occur on many days and this has been interpreted as signifying an anisotropy of primary radiation caused by a source outside the influence of the geomagnetic field. However, there are many days on which the daily variation has a maximum near noon for both directions. On such days the predominant influence is that of a local source situated within the influence of the geomagnetic field. The local source is associated with geomagnetically disturbed days. Long-term changes in the daily variation are found to be similar for the east, vertical and west directions.

Time variations of directional cosmic ray intensity at low latitudes - III. Interpretation of solar daily variation and changes of east-west asymmetry

1961 ◽  
Vol 263 (1312) ◽  
pp. 127-135 ◽  
Keyword(s):  
Energy Spectrum ◽  
Interplanetary Space ◽  
Daily Variation ◽  
Cosmic Ray ◽  
Local Source ◽  
Cosmic Ray Intensity ◽  
The Earth ◽  
Low Latitudes ◽  
Time Variations ◽  
East West

The daily variation of cosmic ray intensity at low latitudes can under certain conditions be associated with an anisotropy of primary radiation. During 1957-8, this anisotropy had an energy spectrum of variation of the form aϵ -0.8±0.3 and corresponded to a source situated at an angle of 112 ± 10° to the left of the earth-sun line. The daily variation which can be associated with a local source situated along the earth-sun line has an energy spectrum of variation of the form aϵ 0 . Increases in east-west asymmetry and the associated daily variation for east and west directions can be explained by the acceleration of cosmic ray particles crossing beams of solar plasma in the neighbourhood of the earth. For beams of width 5 x 10 12 cm with a frozen magnetic field of the order of 10 -4 G, a radial velocity of about 1.5 x 108 cm/s is required. The process is possible only if the ejection of beams takes place in rarefied regions of inter­ planetary space which extend radially over active solar regions. An explanation of Forbush, type decreases observed at great distances from the earth requires similar limitation on the plasma density and conductivity of regions of interplanetary space. The decrease of east-west asymmetry associated with world-wide decreases of intensity and with SC magnetic storms is consistent with a screening of the low-energy cosmic ray particles due to magnetic fields in plasma clouds.

scholarly journals 39. The anisotropy of primary cosmic radiation and the electromagnetic state in interplanetary space

1958 ◽  
Vol 6 ◽  
pp. 377-385
Author(s):  
V. Sarabhai ◽  
N. W. Nerurkar ◽  
S. P. Duggal ◽  
T. S. G. Sastry
Keyword(s):  
Experimental Data ◽  
Cosmic Rays ◽  
Cosmic Radiation ◽  
Interplanetary Space ◽  
Daily Variation ◽  
Cosmic Ray ◽  
The Sun ◽  
Cosmic Ray Intensity ◽  
Daily Variations ◽  
Primary Cosmic Radiation

Study of the anisotropy of cosmic rays from the measurement of the daily variation of meson intensity has demonstrated that there are significant day-today changes in the anisotropy of the radiation. New experimental data pertaining to these changes and their solar and terrestrial relationships are discussed.An interpretation of these changes of anisotropy in terms of the modulation of cosmic rays by streams of matter emitted by the sun is given. In particular, an explanation for the existence of the recently discovered types of daily variations exhibiting day and night maxima respectively, can be found by an extension of some ideas of Alfvén, Nagashima, and Davies. An integrated attempt is made to interpret the known features of the variation of cosmic ray intensity in conformity with ideas developed above.

scholarly journals Galactic Anisotropy of Cosmic Ray Intensity Observed by an Air Shower Experiment

2006 ◽  
Vol 23 (3) ◽  
pp. 129-134
Author(s):  
Mahmud Bahmanabadi ◽  
Mehdi Khakian Ghomi ◽  
Farzaneh Sheidaei ◽  
Jalal Samimi
Keyword(s):  
Daily Variation ◽  
Cosmic Ray ◽  
Cosmic Ray Intensity ◽  
Extensive Air Shower ◽  
Air Shower ◽  
The Earth ◽  
The Galaxy ◽  
Unidirectional Anisotropy ◽  
Galactic Cosmic Ray ◽  
Shower Array

AbstractWe have monitored multi-TeV cosmic rays by a small air shower array in Tehran (35°43′ N, 51°20′ E, 1200 m = 890 g cm−2). More than 1.1 × 106 extensive air shower events were recorded. These observations enabled us to analyse sidereal variation of the galactic cosmic ray intensity. The observed sidereal daily variation is compared to the expected variation which includes the Compton–Getting effect due to the motion of the earth in the Galaxy. In addition to the Compton–Getting effect, an anisotropy has been observed which is due to a unidirectional anisotropy of cosmic ray flow along the Galactic arms.

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