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At least 955 records · Page 53
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

The survival of heavy nuclei in cosmic ray source environments

Results from the Goddard balloon spectrometer and the results reported by Soviet scientists using the Proton series of satellites are summarized. The important experimental results from the balloon spectrometer experiment are as follows: (1) On a total-energy scale, protons constitute only a minor proportion of the cosmic rays, only 20 percent. The rest of the cosmic rays are complex nuclei. (2) All the nuclei have the same power low spectrum in total energy and so the composition seems to be independent of energy.

Balasubrahmanyan, V. K.↗
NASA NTRS1971

Ar-40/Ar-39 ages and cosmic ray exposure ages of Apollo 14 samples.

We have used the Ar-40/Ar-39 dating technique on eight samples of Apollo 14 rocks (14053, 14310), breccia fragments (14321), and soil fragments (14001, 14167). The large basalt fragments give reasonable Ar-40/Ar-39 release patterns and yield well defined crystallization ages of 3.89-3.95 aeons. Correlation of the Ar-40/Ar-39 release patterns with Ar-39/Ar-37 patterns showed that the low temperature fractions with high radiogenic argon loss came from K-rich phases. A highly shocked sample and fragments included in the breccia yield complex release patterns with a low temperature peak. The total argon age of these fragments is 3.95 aeons. Cosmic ray exposure ages on these samples are obtained from the ratio of spallogenic Ar-38 to reactor induced Ar-37 and show a distinct grouping of low exposure ages of 26 m.y. correlated with Cone crater. Other samples have exposure ages of more than 260 m.y. and identify material with a more complex integrated cosmic age exposure history.

Turner, G.↗
NASA NTRS1971

Origin and composition of ultrahigh energy cosmic rays.

Suggestion that, under certain circumstances, the absence of an apparent flattening of the ultrahigh energy cosmic ray spectrum at an energy level above 3 x 10 to the 18th power eV may have implications concerning the origin of ultrahigh energy cosmic rays (UECR). On the basis of the discussion presented, it seems that a heavy composition is indicated. It is therefore concluded that recent air-shower studies seem to indicate the resurrection of the galactic origin model.

Stecker, F. W.↗
NASA NTRS1971

27-day recurrence and long term modulation of cosmic ray intensity.

Previous work by Balasubrahmanyan and Venkatesan (1970) on the general problem of the solar activity relationship with the 27-day recurrence and long term modulation of cosmic ray intensity, and Lockwood's (1971) comments thereon are discussed in the light of some further work. A possible explanation proposed for the absence of any time lag in both short and long term cosmic ray intensity changes views the long term variation as a result of a superposition of a number of short term decreases.

Balasubrahmanyan, V. K.↗
NASA NTRS1971

Energy changes of cosmic rays in interplanetary space.

The observation reported by Murray et al. (1971), in which a feature or ?kink' in the kinetic-energy spectrum of solar cosmic rays from a solar burst was seen to decrease with time, is examined. By means of calculations based on a model for cosmic ray bursts, it is demonstrated that the observed rate cannot be interpreted immediately as the rate of loss of energy, and factors are indicated which must be considered in the interpretation of the data.

Gleeson, L. J.↗
NASA NTRS1972

Gas retention and cosmic-ray exposure ages of a basalt fragment from Mare Fecunditatis.

The Ar40-Ar39 gas retention age and the Ar38-Ar37 cosmic ray exposure age have been determined on a total rock sample of the basalt fragment B-1 returned from Mare Fecunditatis by the Luna 16 mission. This sample shows a large low-temperature loss of radiogenic Ar40 but defines a reasonably good high-temperature plateau at 3.45 plus or minus 0.04 b.y. This is presumed to identify the period of igneous activity in Mare Fecunditatis. This activity is found to be later than that in the area of Mare Tranquilitatis, but earlier than that in the area of Oceanus Procellarum and Mare Imbrium. The cosmic-ray exposure age was found to be 475 m.y.

Huneke, J. C.↗
NASA NTRS1972

Search for antimatter in primary cosmic rays.

Data from two flights of a new superconducting magnetic spectrometer are reported. This instrument was capable of a direct matter-antimatter separation in the cosmic rays. Antimatter events would appear in the spectrometer as trajectories which curve in the opposite direction to common matter, because of their negative charge. A brief description of the equipment and of the characteristics of the instrument is presented, along with the data processing techniques used. A new upper limit on the amount of antimatter in primary cosmic rays has been established. The limits are considerably lower than those for any previous experiment.

Buffington, A.↗
NASA NTRS1972

Transition radiation as a source of cosmic X-rays.

It is shown that transition radiation generated during the passage of relativistic charged particles through interstellar grains can be an important source of cosmic X-rays. In order to account for recent X-ray observations below 300 eV by transition radiation, an energy density in interstellar space of about 10 eV per cu cm in 10 MeV electrons is required. This seems to rule out transition radiation as an important source of diffuse cosmic X-rays in any energy region.

Ramaty, R.↗
NASA NTRS1972

A search for antihelium in primary cosmic radiation.

A search for anti-alpha-particles in the primary cosmic radiation has been carried out, and a new upper limit for these particles in the range 0.2-4.3 GeV per nucleon has been obtained. At the 95 per cent confidence level the upper limit is found to be 0.14 per cent of the alpha-particle flux. The instrument used for this purpose is a magnetic spectrometer employing spark chambers for determining particle trajectories and time-of-flight measurement for the rejection of upward-moving particles. Implications of these results for various models of the sources of cosmic radiation are discussed.

Evenson, P.↗
NASA NTRS1973

Cosmic dust or other similar outer-space particles location detector

Cosmic dust may be serious radiation hazard to man and electronic equipment caught in its path. Dust detector uses two operational amplifiers and offers narrower areas for collection of cosmic dust. Detector provides excellent resolution as result of which recording of particle velocities as well as positions of their impact are more accurately determined.

Aver, S.↗
NASA NTRS1972

The cosmic gamma-ray spectrum between 0.3 and 27 MeV measured on the Apollo 15

The spectrum of the total (diffuse and discrete sources) cosmic gamma-ray background over the 0.3 to 27 MeV range was measured with a 7.0 cm diameter x 7.0 cm long uncollimated NaI(Tl) scintillation counter located on a boom 7.6 m from the Apollo 15 service module. Data on cosmic gamma-rays were taken during transearth coast at various boom extensions, detector gains, and with the plastic anticoincidence scintillator enabled and disabled.

Trombka, J. I.↗
NASA NTRS1972

Satellite measurements of the charge composition of solar cosmic rays in the 6 less than or equal to Z less than or equal to 26 interval

The charge composition of solar cosmic rays were measured during two flares occurring in April and September 1971. The results were derived from a solid state dE/dx vs E telescope which was part of the cosmic ray experiment on the IMP 6 spacecraft. The data suggest that the helium to medium ratio may be varying from one flare to the next. The abundance ratios (normalized to oxygen) are compared with measurements of other investigators and significant disagreements are found. In particular, the data do not exhibit any systematic enhancement of heavy nuclei with respect to the spectroscopic abundances such as previously reported. Finally, the results are compared with the spectroscopically determined coronal and photospheric values, and again several important differences between the two sets of data are found.

Teegarden, B. J.↗
NASA NTRS1970

COSMIC program documentation experience

A brief history of COSMIC as it relates to the handling of program documentation is summarized; the items that are essential for computer program documentation are also discussed. COSMIC documentation and program standards handbook is appended.

Kalar, M. C.↗
NASA NTRS1973

Pioneer-10 measurements of the differential and integral cosmic-ray gradient between 1 and 3 AU

The cosmic-ray experiment on Pioneer has provided measurements of the differential radial gradient of cosmic-ray helium nuclei between 1 and 3 AU. Upper limits are quoted between 10 and 500 MeV/nuc which are everywhere 25%/AU and in some cases substantially smaller. The integral proton gradient ( 56 MeV) was also measured and found to have the following values: 2.4 + or - 0.3%/AU (1-2 AU), 7.6 + or - 0.7%/AU (2-3 AU).

Teegarden, B. J.↗
NASA NTRS1973

Isotopic composition of heavy cosmic rays

The mean isotopic composition was measured of even-charge cosmic ray elements with 14 equal to or less than 26 near 0.8 GeV/N using a balloon-borne ionization-chamber/Cerenkov-counter detector system. The experimental method makes use of the geomagnetic field as a magnetic spectrometer. Results indicate that the most abundant isotopes at the cosmic ray source are Si-28, S-32, and Ca-40, like the solar system; but Fe-54, unlike the solar system.

Maehl, R. C.↗
NASA NTRS1973

Modulation of low-energy galactic cosmic rays over the present solar cycle

Explorer satellite observations of modulations in the cosmic ray spectrum during the entire period of the solar cycle show intensity variations in the proton and alpha modulated spectra. A positive correlation between plasma density and variation in cosmic ray intensity is found that breaks during the transition period when higher energy intensity is decreasing as the solar activity increases. It is suggested that the alpha particles lead the proton particles during transition periods and thus make the lag time shorter for high rigidity near the solar maximum and the solar minimum.

Vanhollebeke, M. A.↗
NASA NTRS1972

Adiabatic propagation of cosmic rays in the Galaxy.

An analysis is presented for the propagation of charged cosmic rays away from a source in a relatively smooth galactic magnetic field. The expected intensity of the resulting narrow-angle anisotropy is related to the particle flux produced by the source. The probable number of such anisotropies is derived, based on the lifetime of cosmic rays and the number of sources in the Galaxy. The agreement with experimental evidence and future possibilities of the model are discussed.

Barrowes, S. C.↗
NASA NTRS1972

Advances in solar and cosmic X-ray astronomy - A survey of experimental techniques and observational results.

The current status of X-ray astronomy is surveyed by reviewing observational results and theoretical conclusions gained within the past two years in areas dealing with the quiet-sun, slowly-varying, and burst components of solar X-radiation and with the features of cosmic X-ray sources. Thermal and nonthermal processes responsible for a wide variety of X-ray emission mechanisms in nature are explained, and characteristics of X radiation from specific solar structures are described. Attention is given to the effects of interstellar and intergalactic matter on cosmic X-rays; the properties of galactic and extragalactic X-ray sources; and the specifications of such instruments as gas-filled ionization detectors, proportional counters, Geiger counters, scintillation detectors, photoelectric detectors, polarimeters, collimators, spectrometers, and imaging systems.

Hoover, R. B.↗