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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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NASA NTRS1972

Interstellar electron intensity

Two independent methods for measuring the electron intensity in interstellar space are proposed. The positron method involves the production of pions in proton-proton collisions, the decay of the pions into muons, and the subsequent decay of the muons into positrons. Results from detailed calculations of these processes are given in graphical form. The second method involves cosmic electron emitted synchrotron radiation in the interstellar magnetic field. These two methods are also used to analyze the spatial and temporal constancy of cosmic ray electrons in the galaxy.

Ramaty, R.↗

NASA NTRS1973

Damping of high frequency waves in the solar wind

Cyclotron damping by suprathermal fluxes of protons and electrons in the interplanetary medium will greatly attenuate high frequency Alfven waves and whistler waves within distances 1 AU of the sun. Electrons with energies between 50 eV to 2 KeV are heated as a result of damping interplanetary whistler waves with frequencies 2 omega meson/2 pion 30 Hz in the frame of the solar wind. This heating may account, in part, for the observed suprathermal tail of solar wind electrons. Protons with energies approximately 50 KeV damp Alfven waves with frequencies .001 omega meson/2 pion .01 Hz. This damping mechanism may explain several features of a scatter free solar electron events and high intensity, anisotropic solar proton streams.

Goldstein, M. L.↗

NASA NTRS1973

Diffuse cosmic gamma rays - Present status of theory and observations.

Theoretical interpretations are proposed for recent positive diffuse gamma-ray flux findings with energy measurements up to the 100 MeV range. Several models of isotropic gamma ray production are considered. Diagrams are plotted to compare the observed background spectrum with (1) an electron bremsstrahlung model, (2) a two-component model involving neutral pion production and decay in cosmic-ray interactions at redshifts up to 100, and (3) a theoretical model involving matter-antimatter annihilation. New results on the diffuse flux from the galaxy are viewed as supporting the pion-decay origin hypothesis for gamma-radiation above 100 MeV.

Stecker, F. W.↗

NASA NTRS1974

Research program in nuclear and solid state physics

The survey of negative pion absorption reactions on light and medium nuclei was continued. Muon spin precession was studied using an iron target. An impulse approximation model of the pion absorption process implied that the ion will absorb almost exclusively on nucleon pairs, single nucleon absorption being suppressed by energy and momentum conservation requirements. For measurements on both paramagnetic and ferromagnetic iron, the external magnetic field was supplied by a large C-type electromagnet carrying a current of about 100 amperes.

Source record↗

NASA NTRS1975

Measurements on the development of cascades in a tungsten-scintillator ionization spectrometer

The response of a tungsten-scintillator ionization spectrometer to accelerated particle beams has been investigated. Results obtained from exposure of the approx. 1000 g/sq cm apparatus to 5, 10, and 15 GeV/c electrons and pions as well as to 2.1 GeV/nucleon C-12 and O-16 ions are presented. These results include cascade-development curves, fractions of the primary energy measured by the spectrometer, and resolutions of the apparatus for measuring the primary energies. For 15 GeV/c electrons, an average of about 82% of the incident energy is measured by the apparatus with resolution (normal standard deviation) of about 6%. For 15 GeV/c pions, an average of about 65% of the incident energy is measured with resolution of about 18%. The energy resolution improves with increasing energy and with increasing depth of the spectrometer.

Cheshire, D. L.↗

NASA NTRS1976

Gamma-rays, cosmic rays, and galactic structure

The relation of SAS-2 observations of galactic gamma-rays to the large scale distribution of cosmic rays and interstellar gas in the galaxy is reviewed. Starting with a discussion of production rates, the case for pion decay being the predominant production mechanism in the galactic disk above 100 MeV is reestablished, and it is also pointed out that Compton gamma-rays can be a significant source near l = 0. The concepts of four distinct galactic regions are defined, viz. the nebulodisk, ectodisk, radiodisk and exodisk. Bremsstrahlung and pion decay gamma-rays are associated with the first two (primarily the first) regions, and Compton gamma-rays and synchrotron radiation are associated with the latter two regions. On a large scale, the cosmic rays, interstellar gas (primarily H2 clouds in the inner galaxy) and gamma-ray emissivity all peak between 5 and 6 kpc from the galactic center. This correlation is related to correlation with other population I phenomena and is discussed in terms of the density wave concept of galactic structure.

Stecker, F. W.↗

NASA NTRS1976

Gamma rays, cosmic rays and galactic structure

Working primarily from the recent SAS-2 observations of galactic gamma rays, the relation of these observations to the large scale distribution of cosmic rays and interstellar gas in the galaxy is reviewed and reexamined. Starting with a discussion of production rates, the case for pion decay being the predominant production mechanism in the galactic disk above 100 MeV is reestablished and it is also pointed out that Compton gamma rays can be a significant source. To facilitate discussion, the concepts of four distinct galactic regions are defined, viz. the nebulodisk, ectodisk, radiodisk and exodisk. Bremsstrahlung and pion decay gamma rays are associated with the first two (primarily the first) regions, and Compton gamma rays and synchrotron radiation are associated with the latter two regions. On a large scale, the cosmic rays, interstellar gas (primarily H2 clouds in the inner galaxy) and gamma ray emissivity all peak in a region between 5 and 6 kpc from the galactic center. This correlation is related to correlation with other population I phenomena and is discussed in terms of the density wave concept of galactic structure. The singular nature of the HI distribution appears to follow the supernova remnant and pulsar distributions in the galaxy.

Stecker, F. W.↗

NASA NTRS1978

Diffuse fluxes of cosmic high energy neutrinos

Production spectra of high-energy neutrinos from galactic cosmic ray interactions with interstellar gas and extragalactic ultrahigh energy cosmic-ray interactions with microwave black-body photons are presented and discussed. These production processes involve the decay of charged pions and are thus related to the production of cosmic gamma-rays from the decay of neutral pions. Estimates of the neutrino fluxes from various diffuse cosmic sources are then made and the reasons fro significant differences with previous estimates are discussed. Predicted event rates for a DUMAND type detection system are significantly lower than early estimates indicated.

Stecker, F. W.↗

NASA NTRS1979

Diffuse fluxes of cosmic high-energy neutrinos

Production spectra of high-energy neutrinos from galactic cosmic-ray interactions with interstellar gas and extragalactic ultrahigh-energy cosmic-ray interactions with microwave blackbody photons are presented and discussed. These production processes involve the decay of charged pions and are thus related to the production of cosmic gamma rays from the decay of neutral pions. Estimates of the neutrino fluxes from various diffuse cosmic sources are then made, and the reasons for significant differences with previous estimates are discussed. Small predicted event rates for a DUMAND (deep underwater muon and neutrino detector) type detection system, combined with a possible significant flux of prompt neutrinos from the atmosphere above 50 TeV, may make the study of diffuse extraterrestrial neutrinos more difficult than previously thought.

Stecker, F. W.↗

NASA NTRS1980

Primary cosmic ray positrons and galactic annihilation radiation

The observation (Leventhal et al, 1978) of positron annihilation radiation at 0.511 MeV from the direction of the Galactic Center is reexamined, suggesting the possibility of a primary positron component of the cosmic rays. The observed 0.511 MeV emission requires a positron production rate nearly two orders of magnitude greater than the production rate of secondary cosmic ray positrons from pion decay produced in cosmic ray interactions. Possible sources of positrons are reviewed with both supernovae and pulsars appearing to be the more likely candidates. If only about 1% of these positrons were accelerated along with the cosmic ray nucleons and electrons to energies not less than 100 MeV, it is believed that these primary positrons would be comparable in intensity to those secondary positrons resulting from pion decay. Some observational evidence for the existence of primary positrons in the cosmic rays is also discussed.

Lingenfelter, R. E.↗

NASA NTRS1981

Neutron star evolution and results from the Einstein X-ray Observatory

The evolution of neutron stars is reexamined using current knowledge of their structure and the available microphysics, including general relativistic effects, improved opacities, and cooling by the emission of neutrinos from a pion condensate or from free quarks. Theoretical cooling curves are compared with observations performed with the Einstein X-ray Observatory. It is found that current soft X-ray observations of pulsars and young supernova remnants do not require stars with a pion condensate or free quarks.

Van Riper, K. A.↗

NASA NTRS1982

Neutron star evolutionary sequences

Detailed numerical calculations which are solutions of the full set of general relativistic equations describing the evolution of a spherical star are presented, for the case of the evolution of neutron stars that are cooling over the central temperatures range of 10 to the 10th to 10 to the 7th K. The effects of nucleon superfluidity in the inner crust and core are included, and models are constructed with and without a pion condensate at high densities. It is found that the localized neutrino cooling which dominates the early evolution of neutron stars is so rapid that heat transport within the star cannot keep pace, and temperature distribution is not isothermal. The residual contraction of the neutron star during the early cooling phase contributes little to the heat budget of the star, and most of the gravitational energy released raises the Fermi energy of the degenerate nucleons. It is concluded that since calculations with and without pion condensate are consistent with the upper limits of current observations, these are not sufficient in distinguishing between the various models of neutron star cooling.

Richardson, M. B.↗

NASA NTRS1984

A 200-MeV pi(+) induced nucleon removal from 24Mg

Nuclear gamma rays in coincidence with outgoing pions and/or protons following single nucleon removal from Mg24 by 200 MeV pi(+) were detected with Ge(Li) detectors. Differential cross sections are reported for gamma rays from the first excited mirror states of Na23 to Mg23 in coincidence with positive pions and/or protons detected in particle telescopes at 30, 60, 90, 120 and 150 deg; angle integrated absolute cross sections and cross section ratios sigma (Mg23/sigma (Na23) are calculated. These results are compared with the predictions of the one step quasifree (OSQF), the intranuclear cascade (INC), and the nucleon charge exchange (NCX) reaction models. The OSQF and the INC calculations generally agree with the experimental results, while the NCX calculations are in disagreement.

Joyce, D.↗

NASA NTRS1985

Secondary antiproton production in relativistic plasmas

The possibility is investigated that the reported excess low energy antiproton component of the cosmic radiation results from proton-proton (p-p) interactions in relativistic plasmas. Because of both target and projectile motion in such plasmas, the antiproton production threshold in the frame of the plasma is much lower than the threshold of antiproton production in cosmic ray interactions with ambient matter. The spectrum of the resultant antiprotons therefore extends to much lower energy than in the cosmic ray case. The antiproton spectrum is calculated for relativistic thermal plasmas and the spectrum is estimated for relativistic nonthermal plasmas. As possible production sites, matter accreting onto compact objects located in the galaxy is considered. Possible overproduction of gamma rays from associated neutral pion production can be avoided if the site is optically thick to the photons but not to the antiprotons. A possible scenario involves a sufficiently large photon density that the neutral pion gamma rays are absorbed by photon-photon pair production. Escape of the antiprotons to the interstellar medium can be mediated by antineutron production.

Dermer, C. D.↗

NASA NTRS1985

Empirical description of the hadron-hadron and hadron-nucleus interaction at the accelerator energy range

Taking into account several assumptions, a formula is transformed into two expressions for kaon and baryon plus antibaryon production in proton interaction and for pion production in pion interactions. Combining both formulae, expression are obtained for the spectrum of kaons and baryons plus antibaryons produced in the meson interactions. For analysis of the cosmic ray propagation in the atmosphere in actual fact, instead of the formulae for interactions of protons and mesons with protons, formulae appropriate for interactions with air nuclei was used. Using the method outlined among others by Elias et al. (1980) simple corrections were introduced to the derived expressions to account for the fact that the target is an air nucleus.

Kubiak, G.↗

NASA NTRS1985

Measurements of hadron mean free path for the particle-producing collisions in nuclear matter

It is not obvious a priority that the cross-section for a process in hadron collisions with free nucleons is the same as that for the process in hadron collisions with nucleons inside a target nucleus. The question arises: what is the cross-section for a process in a hadron collision with nucleon on inside the atomic nucleus. The answer to it must be found in experiments. The mean free path for particle-producing collisions of pions in nuclear matter is determined experimentally using pion-xenon nucleus collisions at 3.5 GeV/c momentum. Relation between the mean free path in question lambda sub in nucleons fm squared and the cross-section in units of fm squared/nucleon for collisions of the hadron with free nucleon is: lambda sub i = k/cross section sub i, where k = 3.00 plus or minus 0.26.

Strugalski, Z.↗

NASA NTRS1985

The effect of the relative nuclear size on the nucleus-nucleus interactions

The experimental data on the interactions of light nuclei (d, He(4), C(12)) at the momentum 4.2 GeV/cA with the carbon nuclei were taken in the 2-m propane bubble chamber. The distributions in the number of interacting nucleons, the spectra of protons, the mean energies of secondary pions and protons, the mean fractions of energy transferred to the pion and nucleon components are presented. The results of the investigation of the mechanism of nucleus-nucleus interactions can be used to calculate the nuclear cascades in the atmosphere.

Erofeeva, I. N.↗

NASA NTRS1985

Study of hadron bundles observed in Chacaltaya two-story emulsion chamber

The existence of hadron-rich families associated with few gamma-ray emission named Centauro and Mini-Centauro phemonena was reported. It was investigated whether these are produced by the special type of interaction different from the ordinary pion multiple production or not. The experimental results are compared with simulation calculation based on ordinary multiple pion production model. Both hadron multiplicity distribution, obtained from the present observation and the simulation calculation, show almost the same distribution which means that hadron bundles of such smaller multiplicities are considered to originate from successive interactions of surviving nucleon with the nature of multiple production during passage through the atmosphere.

Aoki, H.↗