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Orth, C. D.

Publications and source records attributed to Orth, C. D..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Interplanetary propulsion using inertial fusion

Inertial fusion can be used to power spacecraft within the solar system and beyond. Such spacecraft have the potential for short-duration manned-mission performance exceeding other technologies. We are conducting a study to assess the systems aspects of inertial fusion as applied to such missions, based on the conceptual engine design of Hyde (1983) we describe the required systems for an entirely new spacecraft design called VISTA that is based on the use of DT fuel. We give preliminary design details for the power conversion and power conditioning systems for manned missions to Mars of total duration of about 100 days. Specific mission performance results will be published elsewhere, after the study has been completed.

Orth, C. D.↗
NASA NTRS1978

Abundances and spectra for cosmic-ray nuclei from lithium to iron for 2 to 150 GeV per nucleon

Measurements of primary cosmic-ray composition and energy spectra made with a balloon-borne superconducting magnetic spectrometer are described. Results for both 6.7 g/sq cm equivalent vertical atmospheric depth and the top of the atmosphere are presented for the absolute and relative integral abundances, the differential energy spectra, and the spectral indices for cosmic-ray nuclei from Li to Fe and energies of 2 to 50 GeV/n. It is found that propagation effects can explain essentially all the elemental abundances, that the abundances of Li, Be, and B for rigidities below 10 GV/c are consistent with an energy-independent mean interstellar path length of 4.5 + or - 0.5 g/sq cm for the 'leaky box' propagation model, that the abundances of all elements above 10 GV/c are consistent with a path length that decreases as the inverse n-th power of rigidity, and that n equals 0.6 (+0.4, -0.3) for the simplest assumptions made in fitting the source spectra.

Orth, C. D.↗
NASA NTRS1978

A measurement of cosmic-ray beryllium isotopes from 200 to 1500 MeV per nucleon

A balloon-borne superconducting magnetic spectrometer was used in the measurement of cosmic-ray isotopic abundances from lithium through oxygen in the energy range 200-1500 MeV per nucleon. Except for Be-7 all isotopic composition is essentially energy-independent. Be-10 is nearly absent, indicating a mean cosmic-ray age of 6(-3, +10) x 10 to the 6th years. Above about 500 MeV per nucleon, Be-7 drops dramatically in abundance relative to Be-9 and C. By 1500 MeV per nucleon, the relative abundance of Be-7 has become one-half of its lower-energy value. Since Be-7 is the only isotope measured which decays by electron capture, this result is interpreted as indicating that higher-energy Be-7 had an appreciable probability of not being stripped of all its electrons before entering interstellar space where electron pickup is negligible.

Buffington, A.↗
NASA NTRS1978

Relativistic Be-7 - A probe of cosmic-ray acceleration

The cosmic-ray Be-7/Be ratio was observed to be 0.6 below 500 MeV/nucleon, as expected from spallation reactions, but then to drop sharply to 0.4 by 1500 MeV/nucleon. This measurement suggests that primary cosmic rays traverse some material at their sources, producing Be-7 which picks up electrons and decays by K capture during or after the acceleration to relativistic energies. All cosmic rays then enter interstellar space, where further pickup is negligible.

Buffington, A.↗
NASA NTRS1978

Sharpening stellar images

A prototype telescope system with six movable elements has been used with sharpness detection procedures to observe objects as dim as fifth magnitude. The real-time image sharpening technique does not rely on the use of a reference star. By correcting for atmospherically induced phase perturbations, the sharpening system has permitted restoration of stellar images to the diffraction limit (in one dimension) for a 30-cm telescope. Application of the system to the separation of double stars is reported.

Buffington, A.↗
NASA NTRS1977

First observatory results with an image-sharpening telescope

Measurements of characteristic speckle change times are presented for stars observed with an image-sharpening telescope installed and operated on equatorial mounts at Leuschner Observatory in Lafayette, California, and Lick Observatory at Mount Hamilton, California. Despite the short speckle change times encountered, it was possible to record dramatically improved stellar images on nights when the speckles changes relatively slowly. Sharpened images of Sirius and Arcturus are discussed.

Buffington, A.↗
NASA NTRS1976

Secondary cosmic-ray electrons and positrons from 1 to 100 GeV in the upper atmosphere and interstellar space, and interpretation of a recent positron flux measurement

Secondary electron and positron fluxes generated in interstellar space and in the atmosphere from the decays of pions and kaons in inelastic nuclear interactions are calculated by Monte Carlo techniques for lepton energies in the range from 1 to 100 GeV and an assumed thickness of 10 g/sq cm or less for the interstellar or atmospheric material. A simple and accurate analytical model which summarizes the Monte Carlo results and identifies the essential parameters involved is developed and used to interpret a previous positron measurement. It is found that the thickness of interstellar and source material is about 4.3 g/sq cm for cosmic-ray positrons with energies exceeding 4 GeV, a result that is difficult to reconcile with recently proposed two-containment-volume propagation models which predict a thickness of 1.8 g/sq cm for the same energies on the basis of the energy dependence of the measured (Li+Be+B)/(C+O) ratio. It is shown that single-containment-volume (galactic) models invoking an energy-dependent leakage lifetime are compatible with the positron data, but lack a mechanism to explain the energy dependence.

Orth, C. D.↗
NASA NTRS1975

Inelastic-interaction mean free path of negative pions in tungsten

The inelastic-interaction mean free paths (lambda) of 5-, 10-, and 15-GeV/c pions have been measured by determining the distribution of first-interaction locations in a modular tungsten-scintillator ionization spectrometer. In addition to commonly used interaction signatures of a few (2-5) particles in two or three consecutive modules, a chi-squared distribution is employed to calculate the probability that the first interaction occurred at a specific depth in the spectrometer. This latter technique seems to be more reliable than use of the simpler criteria. No significant dependence of lambda on energy has been observed. In tungsten, lambda for pions is 206 (plus or minus 6) g/sq cm.

Cheshire, D. L.↗
NASA NTRS1975

Measurement of primary cosmic-ray electrons and positrons from 4 to 50 GeV

We have used a bremsstrahlung-identification technique to measure electron and positron spectra in the primary cosmic rays from 4 to 50 GeV. Above our average geomagnetic cutoff of 4.0 GV/c, we find fluxes of 4.4 (plus or minus 0.3) electrons and 0.37 (plus or minus 0.09 positrons) per sq m/sr/sec. The electron events follow a differential power law whose spectral index is 2.8 (plus or minus 0.1). Our ratio electrons/(electrons + positrons) = 0.08 (plus or minus 0.02) implies traversal of an equivalent slab thickness of 4.3 (plus or minus 1.5) g/sq cm of interstellar and source material.

Buffington, A.↗
NASA NTRS1975

Search for cosmic-ray antimatter

It appears probable that some fraction of the cosmic rays has extragalactic origin. A search for antimatter nuclei was conducted with the aid of a balloon-borne superconducting magnetic spectrometer. The investigation made use of the fact that matter and antimatter nuclei, because of their opposite signs of charge, would be deflected in opposite directions when passing through a magnetic field. The antimatter flux limits set by the experiments are discussed.

Smoot, G. F.↗
NASA NTRS1975

Inelastic interaction mean free path of negative pions in tungsten

The inelastic interaction mean free paths lambda of 5, 10, and 15 GeV/c pions were measured by determining the distribution of first interaction locations in a modular tungsten-scintillator ionization spectrometer. In addition to commonly used interaction signatures of a few (2-5) particles in two or three consecutive modules, a chi2 distribution is used to calculate the probability that the first interaction occurred at a specific depth in the spectrometer. This latter technique seems to be more reliable than use of the simpler criteria. No significant dependence of lambda on energy was observed. In tungsten, lambda for pions is 206 plus or minus 6 g/sq cm.

Cheshire, D. L.↗
NASA NTRS1974

Search for antinuclei in the primary cosmic rays

Results of a search for primary cosmic-ray antinuclei with charges 2 less than or equal to Z less than or equal to 26 with rigidities above 5 GV/c using a second-generation superconducting magnetic spectrometer with an average bending power of 5.1 kG-m. The addition of new data doubles the sample of cosmic-ray nuclei previously reported and greatly increases the percentage of the more highly charged nuclei.

Smoot, G. F.↗