摘要:

Preliminary measurements of the cosmic ray albedo neutron flux above 400 km are reported for the period June 7 to 17, 1969. The measurements were made with a detector on board the Ogo 6 satellite that responds primarily to neutrons in the energy range 104to 106ev. The latitude variation of the counting rate was found to be 7.4/1 between 90° and 0°, similar to that predicted by Lingenfelter (1963). The neutron counting rate near the poles was found to decrease by 26±5% between 450 and 950 km altitude, corresponding to aR−4.2±0.9dependence, whereRis the distance from the center of the earth. This large altitude dependence excludes any angular distributions of neutron flux at the top of the atmosphere that are more peaked toward the vertical than cos θ (where θ is the angle from the vertical), but it is not in disagreement with an isotropic neutron flux. The total neutron leakage flux found by assuming isotropy was about 0.7 times that predicted by Lingenfelter (1963). The neutron leakage flux values obtained from the Ogo 6 experiment agree with those estimated from other experiments with a similar neutron energy response, if the same angular distribution is used. Estimates of the total neutron leakage flux, deduced from experiments responsive only to neutrons above 1 Mev by using the Lingenfelter (1963) and Newkirk (1963) energy spectra of leakage neutrons, show agreement with the lower energy results when the Newkirk spectrum is used but are up to twice as great as the lower energy results when the Lingenfelter spectrum is

ISSN:0148-0227    

DOI:10.1029/JA075i022p04197

年代:1970

数据来源: WILEY

摘要:

We have made a mass spectrometric determination of the stable xenon isotopes that result from spallation of cesium, cerium, neodynium, dysprosium, and a mixture of rare earth elements by bombardment by 730‐Mev protons. The results obtained suggest that the report that Angra dos Reis fission xenon differs from that in Pasamonte may not be valid, but rather that unusual spallation xenon yields are expected in Angra dos Reis, which complicates estimation of the fission xenon spectrum. Spallation correlation plots should be used with caution because a principal change in the spallation yield with varying targets occurs at Xe130, the isotope commonly used for normalization in such correlation plots. Other isotopes commonly considered remain about the sam

ISSN:0148-0227    

DOI:10.1029/JA075i022p04205

年代:1970

数据来源: WILEY

摘要:

The observations reported here were made with the University of Iowa Injun 5 satellite, which was launched on August 8, 1968, into an orbit of 81° inclination with initial apogee and perigee altitudes of 2525 and 644 km, respectively. The satellite carried an 8.5‐µ thick, totally depleted surface barrier detector, with four discrimination levels, three of which are sensitive to α particles, whereas the fourth is sensitive only to nucleiZ≥3. The following represents a summary of preliminary results, with respect to nucleiZ≥3. (a) Thesteady stateintensity ratio of trapped intensity of (medium mass) nucleiZ≥3 to that of α particles ϵm, ∈α≳0.32 Mev/nucleon is, to an uncertainty of a factor of two,jm/jα∼ 10−3, in theLrange 2 to 4REandBrange 0.15 to 0.25 gauss; the intensityjmis (0.05±0.03) (cm² sec sr)−1. (b) The intensity of nucleiZ≥3 increased by a factor of ∼10² over the steady state value, following the magnetic storms of November 1, 1968, and February 2, 1969; thejm/jαratio on November 8, 1968, had the enhanced value (8±3)×10−3. The results are discussed in the context of the origin of trapped nuclei. It is concluded that the present evidence is inadequate to distinguish between the solar wind and the earth's

ISSN:0148-0227    

DOI:10.1029/JA075i022p04210

年代:1970

数据来源: WILEY

摘要:

We present an analysis of geomagnetic fluctuations as observed at the surface of the earth during the onsets of the main phases of some magnetic storms. We compare the global morphology of these fluctuations with the position of the ring current and plasmapause formed in the magnetosphere as inferred by satellite magnetometer and particle measurements. It is found that the ring current is formed on the innermost disturbedLshells of the magnetosphere. The plasmapause in the cold magnetospheric plasma is at or near the outermostLshell of the relatively undisturbed magnetosphere. When observed, the SAR arc appears on the innermost disturbedLshells of the magnetosphere.

ISSN:0148-0227    

DOI:10.1029/JA075i022p04216

年代:1970

数据来源: WILEY

摘要:

Observations of the geocoronal Lyman α emission rate were obtained as a function of altitude at local midnight near the minimum of solar activity. Solution of the appropriate radiative transfer equations for several hydrogen models, combined with observations of both the solar flux and the extraterrestrial Lyman α background, suggests a reference hydrogen density at 100 km in the range from 6.3×106to 2×107cm−3;, with a best estimate of 1.6×107cm−3. This implies an increase in the hydrogen production rate of nearly a factor of 2 from January 1964 to f

ISSN:0148-0227    

DOI:10.1029/JA075i022p04224

年代:1970

数据来源: WILEY

摘要:

Observations of VLF radio waves traveling via the whistler mode have indicated a common origin for the abrupt frequency shifts of these signals and the simultaneous sudden impulses and sudden commencements of magnetic storms, as registered by ground‐based magnetometers. A study of this relationship suggests that, during the disturbances, observations of whistler mode signals from VLF transmitters can yield useful information on the behavior of the plasmaspher

ISSN:0148-0227    

DOI:10.1029/JA075i022p04230

年代:1970

数据来源: WILEY

摘要:

As a result of the presence of two or more ions with different height profiles in the upperFregion of the ionosphere, propagation ducts that are associated with the lower‐hybrid‐resonance frequency may form. Such ducts are generally oriented along a horizontal direction. These ducts were originally suggested as a mechanism for the explanation of certain VLF hiss bands observed by a number of satellites with electric antennas. They were questioned, however, as a result of detections of VLF noise components at frequencies well above their trapping bands. The conditions in a diffusive equilibrium region under which such ducts may form are investigated. It is found that the ducts are essentially narrow‐band guides with maximum possible bandwidths of the order of 2.5 to 3.0 kHz; the bandwidths vary with altitude. Duct quality is found to depend on the parameters at the ion density crossover level and at theFregion peak. Duct formation is favored by low electron density conditions, thus implying that their existence at high midlatitudes in or near the ionospheric trough is favored. Preliminary examination of data from the VLF receiver connected to the long electric antenna on Alouette 1 revealed a number of hiss events for the year 1963 with bandwidths that fit the duct prope

ISSN:0148-0227    

DOI:10.1029/JA075i022p04235

年代:1970

数据来源: WILEY

摘要:

Whistlers recorded at Eights, Antarctica, in June 1965 were used to measure the electron content in magnetospheric tubes of force in the range 3.5

ISSN:0148-0227    

DOI:10.1029/JA075i022p04249

年代:1970

数据来源: WILEY

摘要:

The Alouette 2 satellite passed over a stable midlatitude red arc on September 28–29, 1967. The electron temperature was measured at the satellite, and a topside sounder determined the electron density structure to theF2peak. The data are used to calculate the intensity and extent of the red arc; heat flow into the ionosphere via thermal conduction is considered as the only energy source. The calculated 6300‐A emission, photometric structure, height of the peak emission, and position of the arc are in general agreement with the observational data of the Fritz Peak airglow observat

ISSN:0148-0227    

DOI:10.1029/JA075i022p04261

年代:1970

数据来源: WILEY

摘要:

Simultaneous balloon observations of auroral N2+(λ3914) emission and bremsstrahlung X rays produced by the precipitation of energetic electrons in the auroral zone suggest that two distinct groups of electrons are responsible for the observed effects. One group is responsible for the major portion of the total precipitated energy during visible aurora, and at times this group not only provides the dominant flux of X rays below about 40 kev but also accounts for most of the cosmic noise absorption. A remarkable feature of this group is the extent to which its average energy may vary, i.e., from several kev to greater than 25 kev during the post‐midnight hours. A second group of particles is responsible for the X ray flux above 50 kev; however, the total power deposited in the atmosphere by this group is seldom greater than a few tenths erg cm−2sec−1. The spectrum of these electrons can be represented by a simple exponential function with anefolding energy usually between 40 and 65 kev. A recognition of these features of the spectrum leads to a better understanding of the relationship between optical, X‐ray, and auroral absorptio

ISSN:0148-0227    

DOI:10.1029/JA075i022p04266

年代:1970

数据来源: WILEY