摘要:

Energetic helium and heavy nuclei (Z≥ 3) were detected in the July 18, 1961, solar particle event. This result brings to four the number of solar cosmic‐ray bursts in which heavy nuclei have been seen. The particles were detected in nuclear emulsions flown on a balloon launched from Fort Churchill shortly after the associated flare appeared on the sun. The average flux of medium nuclei (6 ≤Z≤ 9) during the early part of the solar event was 12.0±1.8 particles m−2ster−1sec−1in the energy interval from 120 to 204‐Mev/nucleon, or about 40 times the normal galactic cosmic‐ray medium nuclei flux at that particular time in the solar cycle. The helium‐to‐medium nuclei ratio in the same energy interval was 79±16. These values are consistent with those anticipated on the basis of the relative abundance of hydrogen, helium, and medium nuclei in other events. Some large nuclei (Z≥ 10) were detected, but light nuclei were so rare that only an upper limit to their abundance could be set (L/M≤ .07). The unbiased acceleration of multiply charged nuclei in every major solar event now seems more certain, and, therefore, it seems to be worth considering this feature in any theory of

ISSN:0148-0227    

DOI:10.1029/JZ071i017p04071

年代:1966

数据来源: WILEY

摘要:

A balloon observation at 3.5 g cm−2over Minneapolis on June 10, 1962, has resulted in upper limits from the quiet sun of less than 0.05 count cm−2sec−1over the range 160 to 800 kev. This limit is considerably below those previously available. The detector consisted of a 3.4‐cm diameter by 5.4‐cm NaI crystal surrounded, except for a 1‐ster forward aperture, by a 14.6‐cm diameter and 20 cm long CsI collimating shield connected in active anticoincidence. The detector was servo‐controlled to observe the sun, 180° in azimuth from the sun, as well as vertical, horizontal, and downward. The differences between the rates pointing to and away from the sun give upper limits for the solar flux at a 95% confidence level of 0.058, 0.048, 0.050, and 0.043 count cm−2sec−1Mev−1over the 163–325, 325–488, 488–651, and 651–774 kev range, respectively. Since the Crab Nebula was in the detector aperture during the flight, these upper limits also apply to that object. Correction for the counter efficiency will give upper limits for the true flux somewhat higher than the above numbers, depending on the shape of the photon spectrum. Observation of the diffuse background γ‐ray spectrum over this range due to cosmic‐ray interactions in the atmosphere gave a result of 0.72 count cm−2sec−1ster−1Mev−1around 300 kev, in general agreement with Peterson's previous results. The atmospheric line at 0.5 Mev due to positron annihilation was resolved. A γ‐ray line at 660 kev was also detected and was determined to be due to Cs137from fallout debris. The implied activity is 8±2×10−3disintegrations per g sec, averaged from 70,000 to 128,000 feet. Additional information pertinent to the application of th

ISSN:0148-0227    

DOI:10.1029/JZ071i017p04079

年代:1966

数据来源: WILEY

摘要:

The theory is extended to include the effects of unequal ion and electron temperatures and a magnetic field. Two approximate formulas for the total scattered power are derived, which, with certain restrictions, are applicable (1) whenTe/Ti≲ 1, (2) whenTe/Ti» 1. For moderately large values of the temperature ratio, a full numerical calculation is necessary. In contrast to the equilibrium case, the total scattered power is not independent of the magnetic field whenTe/Tiis not unity. In the interesting case in which the ion cyclotron radius is large compared to wavelengths of interest, but the electron cyclotron radius is small, the mass ratiome/miis replaced by an effective ratio (me/mi) sec2α, where α is the angle between the propagation vector k and the magnetic field. As α approaches 90°, the effective mass ratio ceases to be small, and the scattering is significantly altered. The general behavior of the scattering has a simple physical explanation. The scattering can be considered to be from acoustic waves that are in equilibrium with the particles that contribute most to their Landau d

ISSN:0148-0227    

DOI:10.1029/JZ071i017p04091

年代:1966

数据来源: WILEY

摘要:

Ion temperature has been measured directly in the height range 700–1000 km with the use of a retarding potential analyzer carried aloft by a rocket. The flight was launched on Oct. 7, 1964, from Wallops Island, Virginia. Local time at apogee was 2258 hr. The ion temperature at apogee (1014 km) was 1200°K with an estimated uncertainty of 15%. Ion temperature asymmetry observed about apogee is interpreted as a cooling of the protonosphere with local time after conjugate point sunset at a rate of approximately 1200°K/hr. This latter result is subject to some uncertainty because of lack of definite knowledge of the rocket attitude. The vertical temperature gradient may be derived after removal of the local‐time variation and is 0.8

ISSN:0148-0227    

DOI:10.1029/JZ071i017p04099

年代:1966

数据来源: WILEY

摘要:

The considerable theoretical work done on the thermal behavior of the ionospheric plasma by Hanson, Dalgarno, Geisler and Bowhill, and other authors is extended here from the steady‐state solutions found by them to a time‐dependent solution that allows the examination of the temperature changes in the ionosphere at dawn. Physical consideration of this problem leads to models that can be mathematically represented by a second‐order, nonlinear, partial differential equation, the numerical integration of which presents serious stability difficulties. An unconditionally stable form of the equivalent difference equation is used in solving numerical examples worked out for models that attempt to represent the dawn ionosphere at summer and winter for both solar cycle maximum and minimum conditions, and the following conclusions are drawn: (a) very substantial heating occurs in the ionosphere before any perceptible increase in ionization. Experimental evidence shows that a measurable increase of ionization begins at a solar zenithal angle of about 95°, while considerable heating starts at angles larger than 110°. (b) As the sun begins to shine on the high atmosphere, the competing effects of increasing heat production and growing heat capacity of the electron gas result in an electron gas temperature that initially rises fast, reaches a peak, and then declines. This peak is more pronounced the higher the altitude and predominates in the winter when the electron concentration buildup is faster. (c) Owing to smaller electron concentration in the summer, the temperatures during this season are higher than in the winter. (d) The much slower rate of increase of electron concentration during the solar cycle minimum period results in a tendency for the temperatures in this period to be higher than during the solar cycle maximum. (e) In most models it is observed that up to the time when the temperature reaches its peak, it is practically height independent at levels above the altitude of maximum heat production. Later a ‘bulge’ is formed at the altitude of maximum heat production, and a negative gradient of temperature exists in the higher levels resulting in an upwar

ISSN:0148-0227    

DOI:10.1029/JZ071i017p04107

年代:1966

数据来源: WILEY

摘要:

The number densities for N2, O2, O, Ar, and He in the 129–200 km range were determined by means of three magnetic mass spectrometers flown aboard an Aerobee rocket launched at the White Sands Missile Range on April 15, 1965, at 0345 MST. The N2and O2abundances, while approximately the same at 120 km as in the 1963 flight, NC 3.115F, were approximately twice as high at an altitude of 200 km. Atomic oxygen number densities were unexpectedly low, despite the semiopen nature of the ion source geometry of the instrument from which they were determined. The ambient temperature variation with altitude was estimated, and evidence for the atmosphere being in diffusive equilibrium during the flight is discusse

ISSN:0148-0227    

DOI:10.1029/JZ071i017p04121

年代:1966

数据来源: WILEY

摘要:

Recently published cross‐sectional information is used to set upper and lower limits to the expected Hα, Hβ, and He I λ5876 emissions due to fast protons and α particles penetrating the atmosphere in the auroral zones. The calculated λ5876 emission per incident α particle is about two times the Hβ emission per incident proton. If the ratio of precipitating α particles to protons in the auroral zones is of the order 0.1, the λ5876 line should be detectable

ISSN:0148-0227    

DOI:10.1029/JZ071i017p04133

年代:1966

数据来源: WILEY

摘要:

The variation of geomagnetic activity with the phase of the moon has been tested for statistical significance. The fluctuations inKp, at the lunar period are typical of the periods near it and in fact are within one standard deviation of the average fluctuation amplitude. Furthermore, theseKpfluctuations appear to be due to the sun. The so‐called 27‐day peak due to the sun (the well‐knownM‐region effect) has a width of about a week and thus is not a sharp peak but contributes to periods between about 24 and 31 days. Any narrow‐banded detection system, such as the superposed epoch analysis, will sense the solar effect anywhere within this broad interval. The 29.5‐day lunar period falls within the interval;Kpanalyses at the lunar period should take into account the nonrandom variation inKpcaused by the broad solar peak. It is shown that previous analyses concluding that there is a significant lunar‐Kpeffect have treated the data so as to disregard the possible solar origin of the effects found. When the solar peak is included in the analyses, the hypothesized lunar effect falls well within the limits of chance occurrence. We conclude that the available data do not indicate any statistically significant lunar influence on geomagnetic activity; the effect at 29.53‐days periodicity that had been attributed to the moon is actually

ISSN:0148-0227    

DOI:10.1029/JZ071i017p04141

年代:1966

数据来源: WILEY

摘要:

A new system for the measurement of the actual momentary values of the Faraday rotation polarization vectors of satellite‐emitted frequencies has been developed. Measurements of the relative polarization angles of the S‐66 satellite‐emitted 40‐ and 41‐Mc/s signals, from which the absolute rotation angle is obtained, have been made at 1‐second intervals. A comparison of momentary polarization angles at 40 and 41 Mc/s made during the center part of overhead satellite passages shows deviations from the expected inverse‐frequency‐squared relation. It has been found that correct raw data can only be obtained from the difference of simultaneous polarization measurements during a short interval when this difference is near π radians. Correction for antenna geometry error and for nonlinear system errors permits electron content evaluation with 1% precision over a latitudinal ra

ISSN:0148-0227    

DOI:10.1029/JZ071i017p04147

年代:1966

数据来源: WILEY

摘要:

Fluxes and energy distributions of trapped electrons and fluxes of trapped protons have been measured at the lower edge of the inner radiation belt following two different energy selective redistributions of electrons at 1.34 Me v and at 0.74 Mev. Each of the two groups of electrons decayed at a rate that was in agreement with atmospheric scattering calculations. Thus it is concluded that at the time of the observations in October–November 1963, scattering by atmospheric collisions was the dominant over‐all loss mechanism for electrons trapped on magnetic shells with 1.145 ≲L≲ 1.160. All electrons on a givenLshell with 0 ≲hmin≲ 350 km decayed at approximately the same rate, consistent with theoretical calculation. The unexpectedly large fluxes of electrons for 0 ≲hmin≲ 150 km and for 1.145 ≲L≲ 1.160 indicate a rather steady injection of electrons at highBvalues by processes in addition to small‐angle atmospheric scattering. The time behavior and the energy spectrum variations suggest that these electrons originated from a pitch‐angle redistribution of some of the electrons trapped at higher altitudes on the same or nearby magnetic field lines. The integral fluxes of protons above ∼70 Mev trapped on magnetic field lines with 1.145 ≲L≲ 1.160 were steady during this same time period. For 200 km ≲hmin≲ 350 km, the measured proton spatial distribution is consistent with that calculated using a source that is uniform in time and space (in this region) and a loss mechanism consisting of atmospheric ionization and excitation. Forhmin≲ 200 km the fluxes of trapped protons did not fall off with de

ISSN:0148-0227    

DOI:10.1029/JZ071i017p04157

年代:1966

数据来源: WILEY