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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 307 records · Page 17

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NASA NTRS1972

Calculation of neutron-decay-proton trapping in the Jovian magnetosphere

Investigations on the possible proton fluxes resulting from cosmic ray albedo neutron decay (CRAND) are summarized. It is recalled that experimental data on the earth's belts are reasonably consistent with a CRAND source for most of the protons with energies 50 MeV in the heart of the inner belt. It is assumed that the CRAND and cosmic ray flux and spectrum for Jupiter are the same as for the Earth, with the significant difference that considerably higher energy particles are needed to reach the Jupiter atmosphere at the same magnetic latitude. The ratio of the CRAND source averaged over an L shell on Jupiter to that on Earth at L = 1.3 is derived from a geometrical calculation. The ratio of average loss rate on Jupiter to that for the Earth is also discussed. The flux around Jupiter is obtained by scaling according to the ratio of source to loss from the flux observed in the Earth's inner belt.

Thomas, J. R.↗

NASA NTRS1972

A measurement of the fast luminescent decay time of P-15 phosphor.

The fast decay time of a 3900-A spectral component of an electron-beam excited P-15 phosphor has been measured using a delayed coincidence technique. The result, 1.04 nsec plus or minus nearly 2%, is in good agreement with previous estimates.

Sutton, J. F.↗

NASA NTRS1972

A measurement of the fast luminescent decays of the MV-50 LED.

The fast luminescent decay of the MV-50 GaAs doped Si light-emitting diode has been studied. This diode is found to provide a fast, inexpensive, bright, and convenient light source for the calibration of fast optical timing systems. A simple passive electronic module is described that allows driving the light source directly by a laboratory pulse generator.

Sutton, J. F.↗

NASA NTRS1972

Decay of isotropic turbulence generated by a mechanically agitated grid.

Experimental study of weak isotropic turbulence, created by a mechanically agitated grid, has indicated that in the absence of large linear-momentum wakes the energy of turbulence relaxes very quickly into a stable self-preserving structure, which, depending on the initial Reynolds number of turbulence, decays at different constant inverse powers of time. Both the longitudinal correlation coefficients and the corresponding spectral distributions, except for the difference in the parametric constants, are of the same functional type as those found previously for a passive grid.

Ling, S. C.↗

NASA NTRS1972

Cosmic gamma-rays from pion decay

The production of gamma rays from the decay of neutral pions produced in interstellar cosmic ray interactions was studied, limited to the total gamma ray intensity. Using the upper-limit gamma ray production, an upper-limit is obtained consistent with that obtained by Kraushaar. It is shown that whatever the shape of the gamma ray spectrum, the normalization has to be consistent with data of the total cross sections.

Stecker, F. W.↗

NASA NTRS1973

Neutral-pion-decay gamma rays from the galaxy and the interstellar gas content

Knowledge of the total gamma ray production rate per H atom from the decay of pion(0) produced in interstellar cosmic ray interactions is essential for determining the possible amount of interstellar H2. This production rate is recalculated using the latest accelerator data on pion(0) production in pp interactions up to approximately 300 GeV. A simple but accurate approximation resolves the past disagreement over the magnitude of this rate. An upper limit is obtained of (1.51 + or - 0.23) x 10 to the minus 25th power/sec. consistent with the observed upper limit of 1.6 x 10 to the minus 25th power/sec.

Stecker, F. W.↗

NASA NTRS1973

Velocity decay and acoustic characteristics of various nozzle geometries with forward velocity

Utilizing a static test stand, 6- by 9-foot wind tunnel and 13-inch circular free jet, aerodynamic and acoustic data were obtained with a convergent circular nozzle, bypass nozzle, 6-tube mixer nozzle, and velocity decay surveys with and without forward velocity. The acoustic data include total sound power, directivity and frequency spectra obtained statically and with forward velocity. The relation of aerodynamic and acoustic measurements statically and in forward flight for the various nozzle configurations are discussed.

Vonglahn, U. H.↗

NASA NTRS1973

Velocity decay and acoustic characteristics of various nozzle geometries with forward velocity.

Utilizing a static test stand, 6- by 9-foot wind tunnel and 13-inch circular free jet, aerodynamic and acoustic data were obtained with a convergent circular nozzle, bypass nozzle, 6-tube mixer nozzle, and 6-tube mixer nozzle with an ejector. The aerodynamic data consist of velocity decay surveys with and without forward velocity. The acoustic data include total sound power, directivity and frequency spectra obtained statically and with forward velocity. The relation of aerodynamic and acoustic measurements statically and in forward flight for the various nozzle configurations are discussed.

Von Glahn, U.↗

NASA NTRS1973

Power law time dependence of river flood decay and its relationship to long term discharge frequency distribution

Investigations have continued into the possibility that significant information on stream flow rates can be obtained from aerial and satellite imagery of river meander patterns by seeking a correlation between the meander and discharge spectra of rivers. Such a correlation could provide the basis for a simple and inexpensive technique for remote sensing of the water resources of large geographical areas, eliminating the need for much hydrologic recording. The investigation of the nature of the meander and discharge spectra and their interrelationship can also contribute to a more fundamental understanding of the processes of both river meander formation and drainage of large basins. It has been found that floods decay with an inverse power law dependence on time. The exponent of this dependence varies from river to river and even from station to station along the same river. This power law time dependence makes possible the forecasting of river discharge with an uncertainty of about 5% for as long as a month following the flood peak.

Schubert, G.↗

NASA NTRS1973

Experiments on the origin of molecular chirality by parity non-conservation during beta-decay

Experiments are described to test a theory for the origin of optical activity wherein the longitudinally polarized electrons resulting from parity violation during radioactive beta decay, and their resulting circularly polarized Bremsstrahlung, might interact asymmetrically with organic matter to yield optically active products. Experiments involve subjecting a number of racemic and optically active amino acid samples to irradiation in a 61700 Ci90SR-90Y beta radiation source for a period of 1.34 years, then examining them for any asymmetric effects by means of optical rotatory dispersion and analytical gas chromatography. In the cases of D,L-leucine, norleucine, norvaline and proline as solids, of D,L-leucine in solution and of D,L-tyrosine in alkaline solution no optical rotation was observed during CRD measurements in the 250-630 nm spectral region. While slight differences were noted in the percent radiolysis of solid D- (12.7%) and L-leucine (16.2%) as determined by GC, no enrichment of either enantiomer was found.

Bonner, W. A.↗

NASA NTRS1973

Neutral-pion-decay gamma rays from the Galaxy and the interstellar gas content

Knowledge of the total gamma-ray production rate per H atom from the decay of neutral pions produced in interstellar cosmic-ray interactions is essential for determining the possible amount of interstellar H2. This production rate is recalculated here using the latest accelerator data on neutral pion production in p-p interactions up to about 1500 GeV. A simple but accurate approximation used here resolves the past disagreement over the magnitude of this rate. An upper limit is obtained of (1.51 plus or minus 0.23) times 10 to the -25th power/sec, consistent with the observed upper limit of 1.6 times 10 to the -25th power/sec.

Stecker, F. W.↗

NASA NTRS1974

Neutral-pion decay gamma rays from the galaxy and the interstellar gas content

The total gamma-ray production rate per H atom from the decay of neutral pions produced in interstellar cosmic-ray interactions is recalculated here using the latest accelerator data on the production of neutral pions in pp interactions up to 300 GeV. A simple but accurate approximation used here resolves the past disagreement over the magnitude of this rate. An upper limit is obtained for this rate by considering a maximum galactic cosmic-ray spectrum taking modulation into account.

Stecker, F. W.↗

NASA NTRS1974

Influence of mixer nozzle velocity decay characteristics on CTOL-OTW jet noise shielding

Jet noise shielding benefits for CTOL engine-over-the-wing configurations were obtained with model scale multitube and lobed mixer nozzles and various shielding surface geometries. Spectral data were obtained with jet velocities from 585 to 1110 ft/sec. Correlation equations for predicting jet noise shielding benefits with single conical nozzle installations were modified to correlate the mixer nozzle data. The modification included consideration of the number of nozzle elements and the peak axial velocity decay in the flow field adjacent to the shielding surface. The effect of forward velocity on jet noise attenuation by a shielding surface is discussed.

Vonglahn, U.↗

NASA NTRS1974

Spectrophotometry of prominences in the phase preceding decay

The results are presented of spectrophotometric processing of prominence spectra in both the quiet and the decay phases. A catalog was compiled of equivalent widths, central intensities, Doppler half-widths, and half-widths of emission lines. The reduced Doppler half-widths of D3 and of the H, K Ca(+) lines obtained in a prominence active phase are much larger than those obtained during a quiet phase. Comparison of the equivalent widths and central intensities of H sub alpha, H sub beta hydrogen and D3 helium lines shows that the values increase in the active phase for the D3 lines and decrease for the H sub alpha, H sub beta lines.

Rakhubovskiy, A. S.↗

NASA NTRS1974

Experiments on the origin of molecular chirality by parity non-conservation during beta-decay

Bonner, W. A.↗

NASA NTRS1975

Influence of mixer nozzle velocity decay characteristics on CTOL-OTW jet noise shielding

Jet noise shielding benefits for CTOL engine-over-wing configurations were obtained with model-scale multitube and lobed mixer nozzles and various shielding surface geometries. Spectral data were obtained with jet velocities from 585 to 1110 ft/sec. Correlation equations for predicting jet noise shielding benefits with single conical nozzle installations were modified to correlate the mixer nozzle data. The modification included consideration of the number of nozzle elements and the peak axial velocity decay in the flow field adjacent to the shielding surface. The effect of forward velocity on jet noise attenuation by a shielding surface is discussed.

Von Glahn, U.↗

NASA NTRS1974

Predictions of three-body-decays of mesons from pole-dominated dispersion relations

The investigation shows that the method of finite dispersion relations (FDR) as developed by Aviv and Nussinov (1970) is consistent with a wide range of three-body meson decays. The specific results vary with each reaction. For each possibility a definite form for the t-channel Regge-pole terms is selected. The results of the investigation indicate the basic reliability of an approach based on the FDR method and the finite-energy sum rules.

Thews, R. L.↗

NASA NTRS1975

Search for monenergetic gamma rays from psi /3684/ decay

Results are reported of a search for monoenergetic gamma rays with energies above 50 MeV arising from psi (3684) decay. The measurements were made by operating an electron-positron storage ring at a center-of-mass energy of 3684 MeV and detecting the secondary gamma rays with large-crystal NaI(T1) spectrometers. No significant evidence is found for the emission of such radiation, and upper limits are placed on such emissions for energies above 50 MeV.

Simpson, J. W.↗