摘要:

A comprehensive study of the intensities of electrons and protons near the equatorial plane in the earth's outer radiation zone is presented. The data were obtained with SUI equipment on Explorer 14 during the five‐month period October 1962 through February 1963. Emphasis is on the radial distribution of absolute intensities of protons and electrons and on the time variations of the energy spectrum and radial distribution of electrons. Typical omnidirectional intensities of electrons in the heart of the outer zone (L∼ 4.0, on the equator) are:Jo(Ee>40 kev) = 3 × 107(cm2sec)−1Jo(Ee>230 kev) = 3 × 106(cm2sec)−1Jo(Ee>1.6 Mev) = 3 × 105(cm2sec)−1The three‐point integral energy spectrum of electrons over the range 40 kev to 1.6 Mev is represented byE−1.0(±0.5)atL= 4.8 for most of the period of the present investigation except during short periods of low‐energy (Ee>40 kev) electron enhancement. The gross temporal variation of the intensities of electrons increases markedly asLincreases from 3.2 to 4.8 and at 4.8 is by factors of about 100 forEe>40 kev, about 10 forEe>230 kev, and about 100 forEe>1.6 Mev. A positive correlation betweenKpdaily sums and equatorial intensities of electronsEe>40 kev is demonstrated. Detailed time histories are given. Slow, inward radial motion of the distribution of energetic electronsEe>1.6 Mev with an apparent velocity of about 0.02Re/day is observed between radial distances of 3 and 4Reafter poststorm enhancement of intensity. Typical omnidirectional intensities of protonsJo(Ep>0.5 Mev) are 7 × 106(cm2sec)−1near the equator for 2.8

ISSN:0148-0227    

DOI:10.1029/JZ069i011p02171

年代:1964

数据来源: WILEY

摘要:

A series of calculations have been carried out to determine the relative importance of ionization from solar‐flare α particles to polar cap absorption events. The exponential rigidity spectrums for solar‐flare radiation discussed by Freier and Webber were used. To illustrate the actual magnitudes involved, typical fluxes, rigidity spectrums, and proton‐α particle ratios from major polar cap events have been used. The electron production rates, electron densities, and specific absorption as a function of altitude for a proton‐α particle ratio of unity are presented for a location with cutoff rigidityPc= 470 Mv. These results indicate that α particles contribute significantly, producing as much as 75 per cent of the ionospheric absorption when the proton‐α particle

ISSN:0148-0227    

DOI:10.1029/JZ069i011p02193

年代:1964

数据来源: WILEY

摘要:

In a previous calculation the equilibrium neutron distribution in the atmosphere produced by interactions of solar protons was derived by a multigroup diffusion code. These calculations are now extended to include the neutron leakage flux up to 10 Mev as a function of energy and angle. The solar proton spectrum was assumed to be of the formdJ/dP=Ke−P/Po. Results are presented as a function of the characteristic rigidityP0and of geomagnetic cutoff rigidity to facilitate comparison with experimental data. Both the calculated neutron albedo and the equilibrium flux within the atmosphere agree with available measurements within the uncertainties of the dat

ISSN:0148-0227    

DOI:10.1029/JZ069i011p02199

年代:1964

数据来源: WILEY

摘要:

The energetic neutron flux at atmospheric depths from 160 to 300 g/cm−2has been measured over latitudes extending from the equator to 55°N geomagnetic. Comparison of data with previous measurements indicates that at the time of these measurements the neutron spectrum was steeper than that determined by Hess et al. for neutrons ofE>60 Mev but was of the same form forE60 Mev was detected on July 21, 1962, over a region from 50° to 55°N geomagnetic. The increase is possibly attributable to a dumping of protons temporarily trapped in the slot between the inner and outer Van Allen z

ISSN:0148-0227    

DOI:10.1029/JZ069i011p02209

年代:1964

数据来源: WILEY

摘要:

Measurements of a piece of the Sputnik 4 fragment which fell in Manitowoc, Wisconsin, on September 5, 1962, yield radionuclide concentrations (at time of fall) as follows: V48, 37±10 dpm/kg; Mn54, 195±25 dpm/kg; and Co60, 39±8 dpm/kg. These results are compared with those obtained by other research groups. It does not appear possible at this time to find a simple explanation that will account for all the da

ISSN:0148-0227    

DOI:10.1029/JZ069i011p02223

年代:1964

数据来源: WILEY

摘要:

The effective production cross sections of a number of radionuclides have been measured in thick iron targets (30 cm by 30 cm by 95 cm) bombarded with collimated beams of 1‐ and 3‐Gev protons. Low‐energy products, Mn54, Cr51, and V48, show varying buildup factors near the front of the target; high‐energy products, Be7, Na24, and P32, show little if any buildup. The buildup factors are larger in the 3‐Gev target and extend to greater depths. All the production cross sections eventually decrease exponentially with depth, corresponding to mean absorption lengths along the primary beam of ∼65 and 125 g cm−2at 1 and 3 Gev, respectively. The radial distribution of the products was measured, and contours of constant concentration were determined. The radial spreading becomes very significant for low‐energy products near the back of the targets, whereas high‐energy products are fairly well collimated along the beam axis. The results of the 3‐Gev experiment are in good agreement with those reported by Honda in 1962. These experiments are helpful for an understanding of the distribution of cosmogenic pro

ISSN:0148-0227    

DOI:10.1029/JZ069i011p02231

年代:1964

数据来源: WILEY

摘要:

Explorer 12 magnetic data show that a positive sudden impulse on the ground is accompanied by an increase in the field strength everywhere within the magnetosphere. Similarly, a negative sudden impulse on the ground is associated with a decrease in the field strength in the magnetosphere. Evidence is also found that the magnetospheric boundary moves outward at the time of a negative sudden impulse. The rise, and fall, time of a sudden impulse is the same everywhere in the magnetosphere (including that portion close to the boundary) and on the ground. Hence this time can be interpreted as the time in which the compression or the expansion of the magnetosphere takes place. The speed of propagation of the field variations through the magnetosphere seems to be close to the hydromagnetic wave speed. The magnitude of a sudden impulse at the satellite level relative to that on the ground is better explained by a magnetospheric model with a curved boundary than by an image dipole model.

ISSN:0148-0227    

DOI:10.1029/JZ069i011p02243

年代:1964

数据来源: WILEY

摘要:

A laboratory experiment is described which simulates some aspects of the interaction of the solar wind and the geomagnetic field. In this experiment, a Mach 2 hydrogen plasma stream from a pulsed coaxial gun was directed against a dipole magnetic field. The shape of the windward side of the magnetic cavity and the circulation of the sheet currents in the boundary were found to be in general agreement with results based on the single‐particle model. But the supersonic‐fluid model is appropriate for the interpretation of further results. A nonluminous arc‐shaped region resembling a bow shock wave appeared upstream from the nose of the cavity, and the plasma was observed to flow irreversibly through this region and around the cavity. Time‐resolved photographs depict the dynamics of the interaction, revealing drifts of the plasma near the interface layer and penetration of the plasma into the magnetic cavity. At times following the impact of the plasma on the field, the field near the magnet was found to be asymmetric and generally lower than the normal dipole field. The recovery time of the field to the dipole value was long in comparison with the decay time of the plasma pulse from

ISSN:0148-0227    

DOI:10.1029/JZ069i011p02257

年代:1964

数据来源: WILEY

摘要:

Results are presented of recent measurements of hydromagnetic emissions made at four Pacific Ocean stations widely separated in both latitude and longitude. The signals are almost always observed simultaneously at the four locations. The repetition frequency of the emission fine structure is found to be highly regular and is the same at all stations for any given hm‐emission event. The structural elements occur simultaneously at stations in the same hemisphere, but the elements are found to be alternately spaced (180° out of phase) at stations on opposite sides of the equator. Hence, energy is being received periodically and alternately in the northern and southern hemispheres. The result is applied to the evaluation of three recently proposed models for the generation of hm emissions; two of the three models are immediately rejected. It is also observed that occasionally the fine‐structure repetition frequency exhibits the presence of a harmonic. This effect, referred to as ‘structure doubling,’ is tentatively interpreted as resulting from a superposition of signals from opposite hem

ISSN:0148-0227    

DOI:10.1029/JZ069i011p02273

年代:1964

数据来源: WILEY

摘要:

Records for a three‐year period, from August 1, 1960, to July 16, 1963, have been examined for the occurrence of hydromagnetic emissions in California. It has been found that hm emissions are more likely to occur in the seven days after geomagnetic storms than during days in geomagnetically quiet period

ISSN:0148-0227    

DOI:10.1029/JZ069i011p02291

年代:1964

数据来源: WILEY