摘要:

A study is made of the intensity of the total radiation in the interplanetary medium before and after the March 28 to April 9, 1960, solar proton events and the March 31, 1960, Forbush decrease as Pioneer 5 moved to a distance of 0.07 AU from the earth. By means of regression plots the space probe ion chamber is compared with a group of neutron monitors and with balloon ion chambers flown at Minneapolis. The comparison covers an energy range from several bev down to 25 Mev. It is found that the ion chamber rates in the period April 10 to April 26,1960, return within approximately 1 per cent to the same regression line observed during the period March 11–28 established before the large solar injection of particles. Thus an upper limit for a possible permanent change in the flux of interplanetary radiation greater than 25 Mev caused by these solar events may be derived using the ion chamber absolute calibration for alternative choice of energies as follows: 5 protons/m2sec ster having energies 25–100 Mev, 10 protons/m2sec ster having energies 100–250 Mev, or 20 protons/m2sec ster having energies 250–1000 Mev.Simpson et al.[1962] have reported a permanent 10 per cent reduction in the interplanetary radiation between 75 Mev and several bev also measured aboard Pioneer 5 during the same events. Very special assumptions about spectral changes are necessary to reconcile these two measu

ISSN:0148-0227    

DOI:10.1029/JZ069i009p01679

年代:1964

数据来源: WILEY

摘要:

The elliptic orbit satellite Explorer 12 made possible the routine survey of the heart of the outer radiation zone as well as the region of transition between the magnetosphere and interplanetary space on the sunward side of the earth by means of a variety of particle and magnetic field detectors. The data received from the SUI detectors during the entire 112‐day lifetime have been comprehensively analyzed. Salient features observed include: confirmation of the enhancement of soft electron fluxes and diminution of hard electron fluxes in the outer zone during magnetically disturbed times; the outward motion of the outer zone hard electron maximum during periods of enhancement; confirmation of the general Chapman and Ferraro picture of a well‐defined magnetosphere with compression of the geomagnetic field during the initial phases of magnetic storms; the existence of a layer of quasi‐thermalized plasma immediately outside the magnetosphere; confirmation of the result of Frank and Van Allen that the contours of constant counting rate for electrons withE≥ 40 kev tend to protrude outward near 90° from the subsolar point and draw closer to the earth on the night side; and general support for the result of Gringauz, Kurt, Moroz, and Shklovskii that there exists a region beyond some 8Reon the night side of the earth dominated by very‐low‐ener

ISSN:0148-0227    

DOI:10.1029/JZ069i009p01691

年代:1964

数据来源: WILEY

摘要:

The approximate calculation of intensities of high‐energy cosmic‐ray muons at sea level given by Smith and Duller is improved by a rigorous calculation for larger zenith angles and higher energies, starting from the integral formula instead of the so‐called diffusion equation of cosmic‐ray mesons in the atmosphere. Similar computations are done to show the contribution of kaons; the results are compared with those of Zatseptin and Kuz′min, who used a different attenuation mean free path. The largest difference between the contributions of pions and kaons appears for muon energies of 100–1000 Gev, as Zatseptin and Kuz′min pointed out. It is shown that measurements of obliquely incident high‐energy muons are helpful in determining the energy dependence of the attenuation mean free path of charged mesons in the atmosphere rather than to distinguish the muon parent particles. To resolve the arguments regarding the additional source of high‐energy cosmic‐ray muons, it is proposed that these observations be extended to

ISSN:0148-0227    

DOI:10.1029/JZ069i009p01725

年代:1964

数据来源: WILEY

摘要:

The measurements of many spectrums of solar protons at northern latitudes have shown that the cutoffs are commonly much lower than those calculated for the earth's magnetic field as deduced from surface measurements, together with any reasonable ring current. We show that most of the observations can be reasonably accounted for with a magnetic field which, in addition to the contributions mentioned, has a turbulent component everywhere beyond a certain distance from the center of the earth. The model is essentially that explored by Parker and by Rothwell. The fact that the solar wind distorts the field at great distances must, as Akasofu et al. suggested, produce a modification, the nature of which we flare is probably the one that began at 1257 UT on this date.

ISSN:0148-0227    

DOI:10.1029/JZ069i009p01737

年代:1964

数据来源: WILEY

摘要:

Reanalysis of radio wave observations of PCA events and balloon measurements of energetic particles leads to the conclusion that two instead of three solar cosmic ray events occurred during late August 1957. This revision involves different flare assignments, and the balloon data show that the delay time between flare beginning and the first arrival of particles at the earth is much less than was reported previously on the basis of radio wave measurements. An importance 3 flare on August 28, 1957, began at 2010 UT. This flare is the most likely source of the solar cosmic rays that began to arrive at the earth after 2140 UT on August 28. Evidence found for an event beginning on August 29, is uncertain. The second cosmic ray event that can be identified during this period began at 1340 UT on August 31. The associated flare is probably the one that began at 1257 UT on this date.

ISSN:0148-0227    

DOI:10.1029/JZ069i009p01743

年代:1964

数据来源: WILEY

摘要:

The equations of motion of a charged particle are integrated through an irregularity in a large‐scale magnetic field. The scattering of the particle is shown to diminish as the cyclotron radius of the particle becomes either large or small compared to the scale of the irregularity and to have a maximum when the radius is comparable to the scale. When the cyclotron radius is large, the order of magnitude of the scattering depends on the number of sequential reverse bends in the lines of force through the magnetic irregularity. It is important for the understanding of modulation of the cosmic‐ray intensity by the solar wind to determine the degree of correlation between adjacent bends in the irregularities in the interplanetary magnetic fi

ISSN:0148-0227    

DOI:10.1029/JZ069i009p01755

年代:1964

数据来源: WILEY

摘要:

Longitudinal drift velocities for charged particles trapped in a realistic representation of the geomagnetic field are calculated for the magnetic shellL= 1.25. It is found that the drift velocity varies with longitude, being as much as 30 per cent greater in the region of magnetic anomalies. The effect of the drift velocity variation on the average atmospheric densities and effective scale heights for trapped particles on this shell is considered. The variation is found to reduce average densities calculated for certain traces of constant (B, L) by 10 to 25 per cent but not to significantly influence calculated values of effective scale heights in the range of altitudes considered.

ISSN:0148-0227    

DOI:10.1029/JZ069i009p01759

年代:1964

数据来源: WILEY

摘要:

The idealized model of the geomagnetic field‐solar wind interaction yields a singular (neutral) point on the magnetopause at which the magnetic field vanishes. If we expand the fields in a power series around this point, including quadratic terms, we can derive an approximate equation of the magnetopause in a small neighborhood of the neutral point which is consistent with the idealized boundary conditions to fourth order. We then consider the additional pressure due to multiple reflections of particles in this neighborhood and show that less than a 4 per cent correction to the single‐reflection pressure condition is necess

ISSN:0148-0227    

DOI:10.1029/JZ069i009p01765

年代:1964

数据来源: WILEY

摘要:

The oblique angle made by the spiral interplanetary magnetic field with the radially expanding solar wind is shown to result in an easterly deflection of the solar wind as it traverses the standing hydromagnetic shock wave a few earth radii upstream of the magnetosphere. A quantitative estimate of the deflection angle can be obtained from the plasma shock relations, which are solved generally to yield the particle density, temperature, magnetic field, and plasma flow field immediately behind the shock front in terms of the corresponding interplanetary (preshock) parameters. For typical values of the interplanetary plasma and magnetic field parameters, the calculated deflection angle lies between 5° and 20°. The earth's orbital velocity relative to the radial solar wind direction contributes approximately an additional 5° deflection. The two effects combined cause the axis of symmetry of the magnetosphere, on the average, to be tilted away from the earth‐sun line as if the solar wind came from an apparent direction between 10° and 25° to the west of the sun. These conclusions are consistent with a considerable body of experimental data and also suggest an alternate explanation for Explorer 10's numerous encounters with the magnetospheric bo

ISSN:0148-0227    

DOI:10.1029/JZ069i009p01769

年代:1964

数据来源: WILEY

摘要:

A year's observations of 54‐Mc/s signals from the satellite Transit 4A have been analyzed. Scintillation indices are presented as functions of latitude, zenith angle, and azimuth. The distribution of these indices is shown in probability plots. The distribution functions are exponential in shape at high and low latitudes and more uniform at intermediate latitudes. At auroral and subauroral latitudes the high values of scintillation index predominate; at middle latitudes the lower values are emphasized. The magnetic control of the scintillation index is clearly seen; when the magnetic index increases, the irregularity structure moves away from the auroral zone. The diurnal pattern as a function of latitude is correlated with spread‐Fphenomena as well as with optical auroral moveme

ISSN:0148-0227    

DOI:10.1029/JZ069i009p01785

年代:1964

数据来源: WILEY