Download or read book Diffuse Galactic Positron Annihilation Radiation and the Underlying Continuum written by Jeffrey George Skibo and published by . This book was released on 1993 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book OSSE Observations of Positron Annihilation in the Galactic Plane written by and published by . This book was released on 1996 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: OSSE has measured the galactic longitude distribution of both the 511 keV annihilation line radiation and the three-photon positronium continuum within ~40 degrees of the center. They have similar shapes, with a composite longitude distribution well represented by an ~11 degrees FWHM Gaussian central bulge together with a possible broad disk component comprising as much as 15% of the integral flux between 40 degrees and 320 degrees longitude. Contributions from one or more discrete source(s) at or near the center with total annihilation radiation (line plus continuum) intensities of up to ~4 x 10(exp -4) photons cu cm sec(exp -1) (2 sigma upper limit) are compatible with the observed distribution. The best estimate of the positronium fraction is 0.97 plus or minus 0.03. No evidence for variation in the positronium fraction is observed.

Download or read book New Extragalactic Perspectives in the New South Africa written by David L. Block and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 676 pages. Available in PDF, EPUB and Kindle. Book excerpt: The date: September 30, 1880 The place: A private observatory in Hastings-on-Hudson Profession of the observer: A medical doctor The instrument: An l1-inch Clark refractor. The significance of that night marked one of the truly great turning points in the development of astronomical techniques: Dr Henry Draper, a wealthy New York medical doctor, had secured the first photograph of a nebula: a 51-minute exposure on a dry gelatinobromide plate showing the wispy nebulosity of the Orion Nebula. By March 1882, Draper had secured an exposure of 137 minutes, showing far richer detail of both bright and dark features. The rest is histapy. The photographic era heralded in a universe where hints of the presence of cosmic dust were strongly alluded to: from star-forming regions such as Messier 17, to the Horsehead Nebula in Orion, to the striking dark finger in the Cone Nebula, to the magnificent dark bands in the plane of our Milky Way. "Historically, astromomers from the very beginning have been afraid of dust.

Download or read book OSSE Observations of Galactic 511 KeV Annihilation Radiation written by and published by . This book was released on 1991 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma-Ray Observatory has performed several observations of the Galactic plane and Galactic center region to measure the distribution of Galactic 511 keV positron annihilation radiation. Preliminary analysis of data collected during the observation of the Galactic center region over the period July 13[24, 1991, indicates the presence of a 511 keV line and positronium continuum superimposed on a power-law continuum.

Download or read book Positron Annihilation in the Galactic Center written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Two separate observations of the .gamma.-ray spectrum originating from the Galactic Center were made by HEAO-3 in the fall of 1979 and in the spring of 1980. The 2.gamma. 511 KeV annihilation line flux decreased by a factor of three over the corresponding six month period, whereas the excess .gamma.-ray continuum below the 511 KeV line, often interpreted as 3.gamma. decay of orthopositronium, barely changed. This apparent discrepancy in the temporal behavior makes it difficult to associate the bulk of the excess continuum with the 3.gamma. decay of positronium. We will show that Compton scattering of the line and high energy radiation provides a natural explanation for the surprisingly small change seen in the excess continuum. 11 refs., 2 figs.

Download or read book Observations of Galactic Positron Annihilation Radiation written by Michael S. Briggs and published by . This book was released on 1991 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissertation Abstracts International written by and published by . This book was released on 1994 with total page 658 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Compton Observatory Science Workshop written by Chris R. Shrader and published by . This book was released on 1992 with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Positron Distribution in the Inner Galactic Ridge written by and published by . This book was released on 1997 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: OSSE was used to measure the longitude and latitude distribution of positron annihilation in the inner galactic ridge using differential measurements relative to intensities at latitudes of plus or minus 10 degrees. An improved understanding of the 50 keV to 10 MeV continua has recently permitted accurate determinations of the positronium continuum flux intensities; this provides an - 5 times greater signal than was available in previous analyses which used only the 511 keV annihilation line. Within the statistical precision of the measurements, the line and positronium continuum components show indistinguishable distributions in both latitude and longitude. A differential measurement of their latitude distributions near the center indicates a narrow Gaussian ridge of -4.4 degrees FWHM. The longitude distribution of the ridge intensity differs from other known galactic ridge radiation distributions in that it shows a narrowly peaked maximum around the center. It can be characterized by an -12 degrees FWHM Gaussian central bulge plus a broad disk-like component. The only physical model based on plausibly associated galactic ridge distributions which can fit the observations well in longitude is the predicted galactic nova spheroid distribution, but scaled down by -2/3 from the latitude-integrated model bulge longitude width. The best fit has no additional discrete source or broad-disk components, although small contributions are permitted by the data. Novae are thought to be progenitors of Type I supernovae, probable sources of positrons in the galaxy, so this correlation suggests that Type I supernovae are the primary source of the positrons producing the observed galactic ridge annihilation radiation.

Download or read book American Doctoral Dissertations written by and published by . This book was released on 1993 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book NASA Conference Publication written by and published by . This book was released on 1992 with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1992 with total page 1572 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Current Perspectives in High Energy Astrophysics written by J. F. Ormes and published by . This book was released on 1996 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Hard X ray and Gamma ray Observation of the Galactic Center Region written by David Miles Smith and published by . This book was released on 1993 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Fifth Compton Symposium written by Mark L. McConnell and published by American Inst. of Physics. This book was released on 2000-04-20 with total page 868 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the Compton Gamma-Ray Observatory (CGRO) now in its ninth year of operation, the Fifth Compton Symposium provided an opportunity for sharing the most recent scientific results from CGRO and other related experiments in gamma-ray astronomy. Equally important were the descriptions of several new space-based and ground-based experiments in gamma-ray astronomy. These new instruments will be responsible for continuing the pioneering efforts of the CGRO mission. The proceedings provide a valuable reference for researchers in high energy astrophysics.

Download or read book Proceedings of the Fourth Compton Symposium Papers and presentations written by Charles Dermer and published by . This book was released on 1997 with total page 1178 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Encyclopedia of Physical Science and Technology written by and published by . This book was released on 2002 with total page 880 pages. Available in PDF, EPUB and Kindle. Book excerpt: Of the Encyclopedia of Physical Science and Technology: Has been completely updated with no less than 90% revised material and 50% new content throughout the volumes Presents eighteen volumes, nearly 800 authoritative articles and 14,500 pages Is lavishly illustrated with over 7,000 photographs, illustrations and tables Presents an increased emphasis on the hottest topics such as information processing, environmental science, biotechnology and biomedicine Includes a final Index Volume containing Thematic, Relational and Subject indexes.