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Meyer, P.

Publications and source records attributed to Meyer, P..

At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Modulation of low energy electrons and protons near solar maximum

The intensities of cosmic-ray electrons in the energy range from 24 to 235 MeV and of protons in the ranges 40 to 150 MeV and greater than 700 MeV are compared with the neutron intensity data over the period 1968 to 1972. Correlation plots between these various components show a marked break following the June 9, 1969 Forbush decrease. The resulting hysteresis curve is best explained as a sudden change in the rigidity dependence of solar modulation. A variation in the size of the solar cavity is also possible but not likely.

Lheureux, J.↗
NASA NTRS1974

Cosmic rays - Astronomy with energetic particles

All nuclei in the periodic table of the elements, as well as electrons and positrons, are present in the stream of cosmic-ray particles. The cosmic-ray particles constitute the only sample of matter from outside the solar system which reaches the earth. Some of the most accurate knowledge of the extrasolar-element abundance distribution is based on the study of these particles. Observational data concerning the cosmic rays are discussed along with cosmic-ray sources, questions of particle interactions and propagation, the electron spectrum, and the significance of the positron component. The directions of cosmic ray research in the immediate future are also considered, giving attention to some fundamental questions which have not yet been answered.

Meyer, P.↗
NASA NTRS1974

Cosmic rays at very high energies - Discussion of some new results

Recent measurements of the nuclear cosmic ray composition up to 100 GeV/n and of the spectrum of cosmic ray electrons to almost 1000 GeV have provided new evidence relevant to the origin of these particles and to their propagation in the interstellar medium. It was shown that the abundance of galactic daughter nuclei decreases with increasing energy relative to the abundance of parent nuclei. It was also found that the energy spectrum of electrons is consistent with a single power law up to 1000 GeV without much steepening. These results are possibly related, and the present work discusses them in terms of (1) a relatively local origin of energetic cosmic rays, (2) an extragalactic origin of the cosmic radiation, and (3) an energy dependent confinement of galactic cosmic rays.

Juliusson, E.↗
NASA NTRS1974

The cosmic ray electron spectrum and its modulation from 1968 through 1972

Over the past five years we have measured the energy spectrum of primary cosmic ray electrons with both a balloon-borne and a satellite absorption spectrometer. All of the balloon flights used identical equipment that was launched each summer from Fort Churchill, Manitoba, Canada. The satellite, OGO-5, has been in an eccentric orbit since March 1968. Together these instruments provide the electron spectrum over a range of energy from 20 MeV to 20 GeV. This wide range and the substantial span of time covered by the measurements permit a detailed study of the solar modulation of electrons. These results are compared with the modulation of the nuclear components as observed by a neutron monitor and interpreted using the cosmic ray transport equation.

Fulks, G.↗
NASA NTRS1973

The spectrum of galactic electrons with energies between 10 and 900 GeV

A cosmic-ray electron detector has been exposed during 1970 in three high-altitude balloon flights from Palestine, Texas. The data analysis is based on results from accelerator calibrations with electrons and pions at SLAC. Discrimination against a contamination of the electron data due to interacting protons has been achieved by statistical methods. The resulting differential energy spectrum of cosmic-ray electrons can be well described by a single power law with spectral index 2.66 plus or minus 0.1 up to energies around 250 GeV. Within the experimental uncertainty, no change in this spectral slope up to almost 1000 GeV can be detected. Some implications of these results are discussed.

Mueller, D.↗
NASA NTRS1973

The carbon/oxygen ratio in high-energy cosmic rays

The abundance distribution of cosmic ray nuclei at 0.6 GeV/nucleon, 1.6 GeV/nucleon and between 20 and 100 GeV/nucleon has been measured by balloon-borne instrumentation. We find that the abundance ratio of carbon to oxygen decreases from 1.1 around 1 GeV/nucleon to a value of about 0.8 at energies above about 30 GeV/nucleon. Some implications of this result are discussed.

Juliusson, E.↗
NASA NTRS1972

Definition phase study of the grand tour missions

The research to define an energetic particle experiment for the OPTGT-MJS missions is reported. The studies reported include: (1) the use of silicon dectectors for low energy, low flux level measurements in the presence of RTG radiation and trapped electrons, (2) high energy proton damage of lithium-drifted and surface barrier silicon detectors, (3) the gas Cerenkov counter, (4) systems for detection of trapped high-energy protons in the presence of trapped electrons, and (5) reliability and redundancy.

Simpson, J. A.↗
NASA NTRS1972

Composition of cosmic-ray nuclei at high energies.

We have measured the charge composition of cosmic-ray nuclei from Li to Fe with energies up to about 100 GeV/nucleon. A balloon-borne counter telescope with gas Cherenkov counters for energy determination was used for this experiment. Our first results show that, in contrast to low-energy observations, the relative abundances change as a function of energy. We find that the ratio of the galactic secondary nuclei to primary-source nuclei decreases at energies above about 30 GeV/nucleon.

Juliusson, E.↗
NASA NTRS1972

The quiet-time spectra of cosmic-ray electrons of energies between 10 and 200 MeV observed on OGO-5.

Measurement of spectra of cosmic-ray electrons of energies between 10 and 200 MeV over a one-year period starting 1968 March. The measurement was made with a detector system on board the OGO-5 satellite. The instrument consists of a solid-state dE/dx detector, a total-energy CsI detector, a gas Cerenkov threshold detector, and two scintillation guard counters. Time periods during which no solar-flare events were recorded were selected for the study. It was found that during these quiet periods there were numerous intensity variations of the electron flux. These variations, which are seen only below 25 MeV, do not show marked correlation with any solar or interplanetary-medium parameters. The flux of the electrons of energies above 25 MeV, on the other hand, showed a gradual decrease over the one-year period, paralleling the neutron monitor intensity. The parameter describing this long-term modulation is almost independent of the rigidity of the electrons in the reported energy range. The physical implication of the finding is discussed.

L'Heureux, J.↗
NASA NTRS1971

The energy spectrum of primary cosmic ray electrons from 2 GeV to 200 GeV.

Use of a balloon-borne counter telescope with a gas Cerenkov counter to measure the energy of primary cosmic ray electrons between 2 and 200 GeV. Electrons are identified by the characteristic electron-photon shower which they produce in a 15 radiation length deep stack of high-Z material interleaved with scintillation counters. Calibrations with monoenergetic electrons up to 14 GeV and monoenergetic protons up to 28 GeV from accelerators are used to develop criteria to statistically separate electrons from proton-induced events. The results from six balloon flights (total exposure time 63 hours) are combined to obtain the electron energy spectrum. Up to about 30 GeV, the spectrum measured in this experiment can be directly checked with calibrations and agrees well with results from other experiments. Above this energy, the flux reported in the present work is somewhat higher than the determinations reported by most other authors. An apparent flattening of the energy spectrum above 50 GeV is not regarded as significant. There is no evidence for a steepening of the spectrum at energies below 200 GeV.

Fanselow, J. L.↗
NASA NTRS1969

Cosmic rays in the Galaxy.

Galactic cosmic rays, discussing chemical composition, isotopic separation, proton and alpha particles energy spectra, propagation, interactions, etc

Meyer, P.↗