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NASA NTRS1985

Relativistic cosmic-ray spectra in the fully nonlinear theory of shock acceleration

The non-linear theory of shock acceleration was generalized to include wave dynamics. In the limit of rapid wave damping, it is found that a finite wave velocity tempers the acceleration of high Mach number shocks and limits the maximum compression ratio even when energy loss is important. For a given spectrum, the efficiency of relativistic particle production is essentially independent of v sub Ph. For the three families shown, the percentage of kinetic energy flux going into relativistic particles is (1) 72 percent, (2) 44 percent, and (3) 26 percent (this includes the energy loss at the upper energy cutoff). Even small v sub ph, typical of the HISM, produce quasi-universal spectra that depend only weakly on the acoustic Mach number. These spectra should be close enough to e(-2) to satisfy cosmic ray source requirements.

Ellison, D. C.↗

NASA NTRS1986

Stopping of relativistic heavy ions in various media

The residual ranges of (900 + or - 3)-MeV/amu gold nuclei accelerated at the Lawrence Berkeley Laboratory Bevalac have been measured in several different media. The energy of the beam of nuclei was measured directly using a new time-of-flight system. The ranges were measured by absorption in linear wedges of polyethylene, carbon, aluminum, copper, tin, and lead and in circular wedges of polystyrene, aluminum, and gold, and by total absorption in nuclear emulsion. The measured ranges were significantly different from those calculated from the best available theoretical estimates of the energy loss of highly charged nuclei. It is concluded that at present energy losses and residual ranges of relativistic heavy ions in an arbitrary medium cannot be predicted with better than an approximately 2 percent accuracy.

Waddington, C. J.↗

NASA NTRS1981

Reliable aerial thermography for energy conservation

A method for energy conservation, the aerial thermography survey, is discussed. It locates sources of energy losses and wasteful energy management practices. An operational map is presented for clear sky conditions. The map outlines the key environmental conditions conductive to obtaining reliable aerial thermography. The map is developed from defined visual and heat loss discrimination criteria which are quantized based on flat roof heat transfer calculations.

Jack, J. R.↗

NASA NTRS1989

Cosmic strings and ultra-high energy cosmic rays

The flux is calculated of ultrahigh energy protons due to the process of cusp evaporation from cosmic string loops. For the standard value of the dimensionless cosmic string parameter epsilon is identical to G(sub mu) approx. = 10(exp -6), the flux is several orders of magnitude below the observed cosmic ray flux of ultrahigh energy protons. However, the flux at any energy initially increases as the value of epsilon is decreased. This at first suggests that there may be a lower limit on the value of epsilon, which would imply a lower limit on the temperature of a cosmic string forming phase transition in the early universe. However, the calculation shows that this is not the case -- the particle flux at any energy reaches its highest value at epsilon approx. = 10(exp -15) and it then decreases for further decrease of the value of epsilon. This is due to the fact that for too small values of epsilon (less than 10(exp -15)), the energy loss of the loops through the cusp evaporation process itself (rather than gravitational energy loss of the loops) becomes the dominant factor that controls the behavior of the number density of the loops at the relevant times of emission of the particles. The highest flux at any energy remains at least four orders of magnitude below the observed flux. There is thus no lower limit on epsilon.

Bhattacharjee, Pijushpani↗

NASA NTRS1984

Low energy antiprotons from supernova exploding in dense clouds

The antiproton spectrum resulting from a supernova, which exploded inside a dense cloud, is calculated by taking into account all energy loss processes including adiabatic deceleration during the expansion phase. The influence of various energy loss processes on the evolution of the spectrum as the supernova expands is investigated. It is shown that if about 25 percent of the cosmic ray nucleons are from such sources, the observed low energy antiprotons can be explained, provided the effect of solar modulation is not very large. The possibility of obtaining enhanced low energy spectrum by this process is also examined.

Stephens, S. A.↗

NASA NTRS1975

Angular distributions in the electron impact excitation of Xe at 20 eV

Electron impact energy-loss spectra of Xe have been studied at 20 eV incident electron energy at scattering angles from 5 to 135 deg. Differential and integral cross sections for elastic scattering and for the excitation of electronic states up to 10.60 eV energy loss have been determined. The validity of the optical selection rules and the previously established angular behavior associated with direct and exchange processes were examined for this intermediate coupling case.

Williams, W.↗

NASA NTRS1977

Analytical study of laser supported combustion waves in hydrogen

A one-dimensional energy equation, with constant pressure and area, was used to model the LSC wave. This equation balances convection, conduction, laser energy absorption, radiation energy loss and radiation energy transport. Solutions of this energy equation were obtained to give profiles of temperature and other properties, as well as the relation between laser intensity and mass flux through the wave. The flow through the LSC wave was then conducted through a variable pressure, variable area streamtube to accelerate it to high speed, with the propulsion application in mind. A numerical method for coupling the LSC wave model to the streamtube flow was developed, and a sample calculation was performed. The result shows that 42% of the laser power has been radiated away by the time the gas reaches the throat. It was concluded that in the radially confined flows of interest for propulsion applications, transverse velocities would be less important than in the unconfined flows where air experiments have been conducted.

Kemp, N. H.↗

NASA NTRS1980

Vibrational kinetics in CO electric discharge lasers - Modeling and experiments

A model of CO laser vibrational kinetics is developed, and predicted vibrational distributions are compared with measurements. The experimental distributions were obtained at various flow locations in a transverse CW discharge in supersonic (M = 3) flow. Good qualitative agreement is obtained in the comparisons, including the prediction of a total inversion at low discharge current densities. The major area of discrepancy is an observed loss in vibrational energy downstream of the discharge which is not predicted by the model. This discrepancy may be due to three-dimensional effects in the experiment which are not included in the model. Possible kinetic effects which may contribute to vibrational energy loss are also examined.

Stanton, A. C.↗

NASA NTRS1982

Further measurements of high energy cosmic ray electrons

The University of Chicago balloon telescope for cosmic ray electrons has been substantially modified and improved, and has been exposed in another successful balloon flight in 1980. Preliminary results from this flight, over the energy range 5 to 200 GeV, are presented. Data indicate an electron flux of 0.27 plus or minus 0.04/(sq m sec sr GeV) at 10 GeV, and a spectral shape consistent with a power law E to the -3.0 power at low energies, but steepening further, probably due to radiative energy losses, with increasing energy.

Mueller, D.↗

NASA NTRS1984

Particle transport in planetary magnetospheres

Particle energization in Earth's and Jupiter's magnetospheres is discussed. Understanding of the large scale magnetic and electric fields in which charged particles move is reviewed. Orbit theory in the adiabatic approximation is sketched. General conditions for adiabatic breakdown at each of three levels of periodicity are presented. High energy losses and lower energy sources argue for the existence of magnetospheric accelerations. Nonadiabatic acceleration processes are mentioned. Slow diffusive energization by particle interactions with electromagnetic fluctuations is outlined. This mechanism seems adequate at Earth but, operating alone, is unconvincing for Jupiter. Adding spatial diffusion in the radially distended Jovian magnetodisk may resolve the difficulty.

Birmingham, T. J.↗

NASA NTRS1985

Analytical calculation of muon intensities under deep sea-water

The study of the energy loss of high energy muons through different materials, such as rock and sea-water can cast light on characteristics of lepton interactions. There are less ambiguities for the values of atomic number (Z) and mass number (A) in sea-water than in rock. Muon intensities should be measured as fundamental data and as background data for searching the fluxes of neutrino. The average range energy relation in sea-water is derived. The correction factors due to the range fluctuation is also computed. By applying these results, the intensities deep under sea are converted from a given muon energy spectra at sea-level. The spectra of conventional muons from eta, K decays have sec theta enhancement. The spectrum of prompt muons from charmed particles is almost isotropic. The effect of prompt muons is examined.

Inazawa, H.↗

NASA NTRS1983

Adiabatic expansion of cosmic ray sources and the consequences for secondary antiprotons

The low-energy antiproton flux measurement of Buffinton et al. (1981) is more than an order of magnitude higher than can be explained by interstellar production. It has been suggested that the excess antiprotons may be created by supernovae in very dense regions of ISM. These sources would provide the additional target material necessary to produce the excess cosmic ray antiprotons; in addition, adiabatic energy losses due to supernova expansion will increase the flux of low-energy antiprotons. The antiproton flux from such sources is examined here, with attention given to the energy loss effects of the adiabatic and collisional losses of both the primary and secondary cosmic ray fluxes. Ionization losses of the antiprotons are also considered.

Mauger, B. G.↗

NASA NTRS1987

Energetics of the shock potential

It is shown that the difference between proton energy loss and electron energy gain can be understood from a knowledge of the asymptotic properties of the shock that are derivable from the Rankine-Hugoniot relations. No reference to a component of the magnetic field that is out of the coplanarity plane is required. At the same time, we show that such a field does exist and calculate its magnitude.

Jones, Frank C.↗

NASA NTRS1999

Process for Making Carbon-Carbon Turbocharger Housing Unit for Intermittent Combustion Engines

An improved. lightweight, turbine housing unit for an intermittent combustion reciprocating internal combustion engine turbocharger is prepared from a lay-up or molding of carbon-carbon composite materials in a single-piece or two-piece process. When compared to conventional steel or cast iron, the use of carbon-carbon composite materials in a turbine housing unit reduces the overall weight of the engine and reduces the heat energy loss used in the turbo-charging process. This reduction in heat energy loss and weight reduction provides for more efficient engine operation.

Northam, G. Burton↗

NASA NTRS1973

Electron impact excitation and assignment of the low-lying electronic states of N2O

Electron scattering spectra of nitrous oxide are reported in the 5- to 10-eV energy-loss range at scattering angles of 20, 30, 90, and 130 deg at a residual energy of 7.0 eV; and at residual energies of 10.0, 2.0, 1.0, 0.6, and 0.2 eV at a scattering angle of 90 deg. Several new distinct and overlapping continua are observed to lie in this energy-loss range. The experimental spectra are discussed in the light of semiempirical INDO calculations of Chutjian and Segal (1972) of the vertical transition energies of N2O. An assignment of the symmetries of the observed excitations consistent with the experimental and theoretical data is suggested.

Hall, R. I.↗

NASA NTRS1985

Multiple Scattering Effects in de/dx-E Instruments for Isotopic Composition Studies

The development of cosmic ray telescopes to separate individual isotopes of heavy elements using the dE/dx-vs.-E technique depends on the incorporation of precise trajectory sensing elements into these systems. In typical implementations the particle trajectory is derived from a set of position measurements made prior to a particle's entering the first energy loss detector. The use of the trajectory obtained in this way to correct energy loss signals for the actual pathlengths through the detectors depends on the assumption that the particle trajectory is a straight line. In order to resolve iron isotopes the angles of incidence, theta the particle track must be known rather accurately.

Wiedenbeck, M. E.↗

NASA NTRS2017

Proton Straggling in Thick Silicon Detectors

Straggling functions for protons in thick silicon radiation detectors are computed by Monte Carlo simulation. Mean energy loss is constrained by the silicon stopping power, providing higher straggling at low energy and probabilities for stopping within the detector volume. By matching the first four moments of simulated energy-loss distributions, straggling functions are approximated by a log-normal distribution that is accurate for Vavilov k is greater than or equal to 0:3. They are verified by comparison to experimental proton data from a charged particle telescope.

Selesnick, R. S.↗

NASA NTRS1982

X-ray and gamma-ray upper limits for pulsed emission from radio pulsars

Results are given for an HEAO 1 search for pulsed emissions from 11 radio pulsars, in the 15 keV-11 MeV energy range. The upper limits of the Vela pulsar are found to fall below the low-energy extrapolation of the more than 50 MeV pulsed spectrum observed by the COS B satellite, and while consistent with predictions of a polar cap acceleration model, seem barely consistent with a single power-law interpolation between optical intensity and the 50 MeV intensity. High energy X-ray upper limits for seven of the ten other pulsars, which were chosen on the basis of proximity to earth, high rotational energy loss rates and short periods, are found to be only a few percent of their rotational energy losses, assuming a moment of inertia, an emission solid angle, and a pulse duty cycle, that are all similar to the high energy X-ray duty cycle of the Crab pulsar. These upper limits are below the corresponding fraction for the Crab pulsar in the cases of the Vela pulsar, PSR 1929+10 and PSR 1642-03.

Knight, F. K.↗