摘要:

On the basis of earlier work that suggested that the sidereal diurnal variation in cosmic ray intensity could be due to the cooperative effects of the interplanetary magnetic field and a radial heliocentric cosmic ray density gradient, a more comprehensive data analysis has been made to test the model. Data from underground μ meson telescopes in the northern and southern hemispheres have been analyzed in sidereal time as a function of the direction of the interplanetary magnetic field. The observed anisotropy is shown to be dependent on the magnetic field direction. Sidereal cosmic ray data from several underground detectors are displayed as a function of the threshold rigidity of the detectors, and the results appear to indicate that the mechanism responsible for the ‘sidereal’ anisotropy has an upper cutoff rigidity below 100 Gv. Other observed sidereal cosmic ray anisotropies are reviewed in the light of these results, and the likelihood of observing a true sidereal anisotropy above and below 100 Gv is discu

ISSN:0148-0227    

DOI:10.1029/JA076i019p04217

年代:1971

数据来源: WILEY

摘要:

The results on the nucleonic component of the primary cosmic rays obtained from the analysis of 5800 orbits of data (March 8, 1968, to May 10, 1969) from the University of Rochester telescope on Oso 3 satellite are presented. The results indicate that the slopes of the integral rigidity spectrumJ(>R) =AR−γparticles/m2sec ster of helium, medium (6≤Z≤9), and heavy (Z≥10) nuclei above a rigidityRof about 8 bv are the same (γ = +1.47 ± 0.05). The heavy to medium ratio is found to be 0.32±0.06 constant with rigidity in the region

ISSN:0148-0227    

DOI:10.1029/JA076i019p04224

年代:1971

数据来源: WILEY

摘要:

Comprehensive measurements of protons, α particles, andZ>3 nuclei ofE≳0.5 Mev/nucleon obtained with the lunar‐orbiting Explorer 35 spacecraft for the period July 20, 1967, to May 14, 1968, are reported. The major results of this study are the following, (a)Protons ofE≥0.5 Mev are present (exceeding 1.3 (cm2sec ster)−1) in the interplanetary medium at least 63% of the time. (b)Protons, α particles andZ≥3 (medium) nuclei always appear together although in variable mixtures. (c)Events with harder proton spectrums have smallerp/α ratios. (d)The α/Mnuclei ratio of 20±10 characterizes most events. (e)The event‐integratedp/α ratio varies from 10 to 150. (f)There exists a directional anisotropy in thep/α ratio, believed to be observed for the first time. (g)By combining spectroscopic data of Lambert (1967) with the observed α/Mratio, a value of ∼50 for thep/α ratio at the sun is obtained. The data are discussed in the context of particle propagation and properties of t

ISSN:0148-0227    

DOI:10.1029/JA076i019p04230

年代:1971

数据来源: WILEY

摘要:

During the February 25, 1969, solar proton event, particle measurements from the close‐orbiting satellite Esro 2, and particle and magnetic field measurements outside the magnetosphere from the Heos A1 satellite are available. The Esro 2 data for proton energies fromE>27 toE>90 Mev show intensity enhancements in the auroral zone region and in the central polar region relative to the rest of the polar cap. At energies of a few million electron volts such enhancements are significantly less marked. By comparison of observations inside and outside the magnetosphere and by suitable trajectory computations inside the magnetosphere, we explain the auroral zone enhancements at energies>27 Mev in terms of a form of impact zone effect allied to a particle anisotropy outside the magnetosphere. We suggest that the enhancements observed over the polar region may be due to the particle anisotropy outside the magnetosphere plus coupling between the central polar cap lines of force and the interplanetary field line

ISSN:0148-0227    

DOI:10.1029/JA076i019p04245

年代:1971

数据来源: WILEY

摘要:

During the energetic solar particle event that began on January 24, 1969, the ratioN/Sof the intensity of protonsEp>0.3 Mev over the earth's north (N) polar cap (Λ>80°) to that over its south (S) polar cap (−Λ>80°) varied from a value greater than 20 to about 1, as observed with satellite Injun 5 in a low‐altitude polar orbit. The interplanetary intensity of protons was measured simultaneously with similar detectors on Explorer 33 and 35 in two nearly orthogonal planes and in 8 different directions on the unit sphere (some overlap). High values of the N/S ratio early in the event corresponded to an extraordinarily strong anisotropy of intensity in interplanetary space with the anisotropy vector pointing dominantly southward. The N/S ratio dropped toward 1 as the interplanetary beam relaxed toward isotropy. Similar, although less well determined, findings applied to protonsEp>3.4 Mev and α particlesEα>1.18 Mev. The directions of interplanetary field lines that connect with the respective polar caps are uniquely identified by intensity considerations. The interplanetary magnetic vector was measured on Explorer 35 also. Early in the event, the earth was in a solar positive (Boutward from the sun) magnetic sector (ϕSE≈140°), with a dominantly southward direction (θSE≈−40° to −70°). The anisotropy vector was approximately parallel to the magnetic vector and in the same sense. The composite evidence favors the direct access of energetic particles to the earth's polar caps via magnetic field lines interconnected between the terrestrial field and the interplanetary medium; it strongly contradicts models that contemplate diffusion across the magnetospheric tail as an important feat

ISSN:0148-0227    

DOI:10.1029/JA076i019p04262

年代:1971

数据来源: WILEY

摘要:

Differential energy measurements were made on board the low‐altitude (∼500 km) polar‐orbiting satellite OV1‐18 of protons (1.4–46 Mev) and α particles (7–22 Mev) during several solar particle events in 1969 and 1970. The measured 1/ecutoffs for ∼2‐Mev protons show the same general variation with local time as those calculated by Smart et al. (1969) but are displaced to somewhat lower latitudes, even at times of low magnetic activity. The rate of change of cutoff latitude with rigidity is generally less on the nightside than on the dayside, with the α particle 1/ecutoffs being consistent with the cutoffs for protons of the same rigidity. At a given particle energy the curves of flux versus latitude are nearly always steeper on the nightside than on the dayside, with large variations from one pass to the next sometimes occurring in the slopes of the flux profiles near cutoff. The profiles of counting rate versus latitude are often smooth near the boundary, but sometimes pronounced flux and spectral variations with time and/or latitude are observed. At low latitudes on the dayside, protons with pitch angle distributions peaking near 90° appear even at positions where the calculatedB,Ltraces of the observation points show that the particles could have drifted westward, at a constant μ, only a few degrees in longitude. On the dayside, the fluxes of trapped protons that could have been injected on the nightside often extend to lower latitudes than those that could not have drifted very far in longitude, thus suggesting that these protons were indeed injected on the nightside and that they underwent diffusion as they d

ISSN:0148-0227    

DOI:10.1029/JA076i019p04276

年代:1971

数据来源: WILEY

摘要:

We present a theoretical and experimental study of the production and propagation of atmospheric secondary negatrons, positrons, and photons moving in the vertical direction. The one‐dimensional transport equations have been solved numerically to obtain energy spectra and intensity versus depth for energies as low as 4 Mev and for atmospheric depths up to 400 g/cm2. The calculations are performed for the solar modulation level of 1968 and geomagnetic cutoff values of zero and 4.5 Gv. We also present experimental data on negatrons and positrons in the energy range from 6.5 to 200 Mev obtained from balloon observations near Ft. Churchill, Canada, in 1968. The comparisons with measurements confirm the calculated energy spectra and intensity versus depth. The spectral shapes of secondary negatrons and positrons are found to be very dependent upon the atmospheric depth. In the high atmosphere, the photon spectrum below ∼70 Mev is dominated by bremsstrahlung from primary and reentrant albedo electrons rather than by π0decays. The derived intensity versus depth deviates distinctly from the commonly assumed linear growth of the secondary flux with increasing depth. Our results on the functional depth dependence are useful for determining the contribution from atmospheric secondaries to measurements of the electron (and photon) flux at balloon altit

ISSN:0148-0227    

DOI:10.1029/JA076i019p04291

年代:1971

数据来源: WILEY

摘要:

The shape of the Lyman α line emitted by the whole solar disk has been measured with an experiment on board the Oso 5 satellite during the year 1969. The intensity of the line in a 100 A bandpass was measured, and the use of two resonance cells, one filled with hydrogen and the other one with deuterium, gave the intensity of the line at the center and on the blue wing with a resolution better than 0.02 A. These measurements showed that the shape of the line changes considerably with solar activity, owing to variations in intensity at the center of the line, which are much greater than on the blue wing or averaged over the whole line

ISSN:0148-0227    

DOI:10.1029/JA076i019p04311

年代:1971

数据来源: WILEY

摘要:

The active cavity radiometer type II, a new and accurate standard detector, has been developed for the absolute measurement of optical radiant flux. The active cavity radiometric scale (ACRS), defined by the active cavity radiometer (ACR), and the international pyrheliometric scale (IPS), defined by a U.S. standard angstrom pyrheliometer, have been compared in recent experiments. Simultaneous measurements of solar irradiance demonstrated an average systematic difference between the two scales of 2.2%, the measurements on the ACRS exceeding those on the IPS. An analytical study of the sensitivity of the ACR to sources of experimental error is presented. The uncertainty in the ACRS is found to be less than ±0.5% at the one solar constant level relative to the absolute scale based on fundamental physical principles. In August 1968 two ACR's measured the solar irradiance at an altitude of 25 km in a balloon‐flight experiment. The solar‐constant value derived from this measurement wasHo= 137.0 mw

ISSN:0148-0227    

DOI:10.1029/JA076i019p04325

年代:1971

数据来源: WILEY

摘要:

Interplanetary dust grains saturated with solar wind gases may act as sources of H and He in the inner solar system. Calculations for the density and fluxes of these gases are given in terms of the basic dust size distribution function. Owing to the lack of agreement between the different experimental data, it is not possible to fully assess the importance of this process. By using the data available, H and He densities in the ranges 8×10−7to 6×10−3cm−3and 6×10−8to 5×10−4cm−3can be predicted at 1 AU. Depending on the true effective area of the dust particles, the higher He densities could be adequate to explain the presence of4He+in

ISSN:0148-0227    

DOI:10.1029/JA076i019p04341

年代:1971

数据来源: WILEY