SOME FEATURES OF THE RESPONSE OF NEUTRON MONITORS TO LOW-ENERGY PARTICLES INCIDENT ON THE TOP OF THE ATMOSPHERE

1962 ◽  
Vol 40 (7) ◽  
pp. 906-923 ◽  
Author(s):  
William Webber
Keyword(s):  
Solar Flare ◽  
Sea Level ◽  
Ring Current ◽  
Internal Field ◽  
Low Energy ◽  
Intensity Increase ◽  
Neutron Monitors ◽  
Solar Particle Events ◽  
Yield Functions ◽  
Geomagnetic Cutoff

By comparing the measured intensities and spectra of solar particles at the top of the atmosphere with measured neutron monitor intensity increases at sea level for several solar particle events, a set of yield functions has been derived for these neutron monitors in terms of low-rigidity (0.5–2 BV) particles incident on the top of the atmosphere. The monitors are found to be significantly more sensitive to these low-rigidity particles than has recently been believed. Various characteristics of the response of neutron monitors to solar flare particles are discussed. In particular a method is described by which the intensity increase vs. latitude curve for the neutron monitors during these events can be utilized to derive a measurement of the deviations in geomagnetic cutoff from those expected from the earth's internal field only. Applying this to the November 15, 1960, event suggests that a ring current of moment M = 0.6 ME and radius R = 7.7 RE was flowing at 1130 U.T. on this day.

scholarly journals Effect of Solar Modulation on the Low Energy Sea Level Muon Spectrum Near the Geomagnetic Equator

1978 ◽  
Vol 31 (5) ◽  
pp. 451 ◽  
Author(s):  
DP Bhattacharyya
Keyword(s):  
Experimental Data ◽  
Sea Level ◽  
Low Energy ◽  
Solar Modulation ◽  
Recent Experimental Data ◽  
Geomagnetic Equator ◽  
Muon Spectrum ◽  
Muon Intensity ◽  
Theoretical Results

A study is made of the influence of long-term solar modulation on the low energy sea level muon spectrum near the geomagnetic equator. Recent experimental data are compared with theoretical results calculated from the phenomenological model of Allkofer and Dau. It is suggested that the observed enhancement in the muon intensity is mainly due to a shift in the solar potential.

Acceleration, Containment, and Emission of Very Low Energy Solar Flare Particles

1974 ◽  
pp. 461-469 ◽  
Author(s):  
R. P. Lin ◽  
R. E. McGuire ◽  
K. A. Anderson
Keyword(s):  
Solar Flare ◽  
Low Energy

LOW ENERGY PROTON FLUX AT SEA LEVEL

1959 ◽  
Vol 37 (1) ◽  
pp. 79-81 ◽  
Author(s):  
I. B. McDiarmid
Keyword(s):  
Sea Level ◽  
Low Energy ◽  
Proton Flux ◽  
Energy Proton

The relation between latitude and solar-cycle variations in the neutron-monitor mass-absorption coefficient

1968 ◽  
Vol 46 (10) ◽  
pp. S1087-S1089 ◽  
Author(s):  
Miriam A. Forman
Keyword(s):  
Solar Cycle ◽  
Absorption Coefficient ◽  
Sea Level ◽  
Neutron Monitor ◽  
Mass Absorption Coefficient ◽  
Cutoff Rigidity ◽  
Neutron Monitors ◽  
Solar Cycle Variation ◽  
Mass Absorption ◽  
Pressure Altitude

The differential mass-absorption coefficient for rigidities between 2 and 15 GeV/c for IGY-type neutron monitors at sea level and at 500 mm Hg pressure altitude has been calculated from the variation of the neutron-monitor intensity and mass-absorption coefficient with cutoff rigidity. Combined with six sea-level surveys of neutron-monitor intensity between 1954 and 1962, and assuming no time variation in the neutron-monitor mass-absorption coefficient above 15 GeV/c cutoff, the calculated differential mass-absorption coefficient implies a solar-cycle variation of about 0.04%/mm Hg at 2 GeV/c cutoff rigidity at sea level.

scholarly journals Dual source populations of substorm-associated ring current ions

2009 ◽  
Vol 27 (4) ◽  
pp. 1431-1438 ◽  
Author(s):  
M. Yamauchi ◽  
Y. Ebihara ◽  
I. Dandouras ◽  
H. Rème
Keyword(s):  
Ring Current ◽  
Early Morning ◽  
High Energy ◽  
Low Energy ◽  
Narrow Energy Range ◽  
Different Temperatures ◽  
Energy Domain ◽  
Dual Source ◽  
Cold Component ◽  
Source Populations

Abstract. Sources of low-energy ring current ions in the early morning sector (eastward drifting energy domain of about <5 keV) are examined using both statistical analyses and numerical tracing methods (phase-space mapping and simulation). In about 90% of Cluster perigee traversals at 02~07 local time, these low-energy ring current ions have dual ion populations: one is wedge-like energy-dispersed ions, and the other is a band-like ions over different latitudes in a narrow energy range at the upper energy threshold of the wedge-like energy-dispersed ions. Both components are most likely created during past substorm activities. Numerical tracing results strongly suggest that these two components have different sources with different temperatures and elapsed times. The band-like part most likely comes from ions with plasma sheet temperature (~1 keV), and the energy-dispersed part most likely comes from cold ions (temperature <0.1 keV). The source density of the cold component (0.2~0.5×106/m3) is slightly less than that of the hot component (0.5×106/m3), while Cluster observation shows slightly higher density for the wedge-like part than the low-energy band-like part. The hot source component also explains the observed high-energy (>10 keV) ions drifting westward after adiabatic energization in the nightside under time-varying electric field. The wedge-like part has much shorter elapsed time, i.e., less charge-exchange loss, than the band-like part.

scholarly journals Variations of Interplanetary Parameters and Cosmic-Ray Intensities

1980 ◽  
Vol 91 ◽  
pp. 393-398
Author(s):  
A. Geranios
Keyword(s):  
Solar Flare ◽  
Recovery Time ◽  
Propagation Speed ◽  
Cosmic Ray ◽  
Interplanetary Shocks ◽  
Fast Solar Wind ◽  
Neutron Monitors ◽  
Cosmic Ray Intensity ◽  
Cosmic Ray Modulation ◽  
Modulation Region

Observations of cosmic ray intensity depressions by earth bound neutron monitors and measurements of interplanetary parameter's variations aboard geocentric satellites in the period January 1972-July 1974 are analysed and grouped according to their correlation among them. From this analysis of about 30 cases it came out that the majority of the depressions correlates with the average propagation speed of interplanetary shocks as well as with the amplitude of the interplanetary magnetic field after the eruption of a solar flare. About one fourth of the events correlates with corotating fast solar wind streams. As the recovery time of the shock-related depressions depends strongly on the heliographic longitude of the causitive solar flare, it seems that the cosmic ray modulation region has a corotative-like feature.

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