Download or read book OSSE Observations of Galactic 511 KeV Positron Annihilation Radiation Initial Phase 1 Results written by and published by . This book was released on 1993 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma-Ray Observatory (GRO) has performed numerous observations of the galactic plane and galactic center region to measure the distribution of galactic 511 keV positron annihilation radiation and to search for time variability of the emission; the initial 511 keV line fluxes for the observations performed during the first 18 months of the GRO mission are presented. The 511 keV line flux for a typical galactic center observation is (2:5 plus or minus 0:3) x 10(exp -1) gamma sq cm s(exp -1), where the quoted uncertainty represents the 1 sigma statistical uncertainty. No statistically significant time variability of the line flux has been observed; the 3 sigma upper linit to daily variations from the mean is 3 x 10(exp -4) gamma sq cm s(exp -1). The distribution of galactic 511 keV positron annihilation radiation implied by the OSSE observations is discussed and compared with observations by other instruments.
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 The Distribution of Galactic 511 KeV Positron Annihilation Radiation written by and published by . This book was released on 1994 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Oriented Scintillation Spectrometer Experiment (OSSE) on NASA's Compton Gamma-Ray Observatory has completed numerous observations of the Galactic plane and Galactic center region. A principle objective of these observations was to measure the distribution of the Galactic positron annihilation radiation. Most of these observations provided positive detections of the narrow 511 keV annihilation line. These data were fitted using several diffuse distribution models representing various populations of progenitor objects. The only model investigated which is not rejected is a two-component distribution consisting of spheroidal and disk components; all other models investigated can be rejected at the> 4:5 sigma confidence level. The size of the spheroidal component is found to be
Download or read book Handbook of X ray and Gamma ray Astrophysics written by Cosimo Bambi and published by Springer Nature. This book was released on with total page 5912 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 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 International Aerospace Abstracts written by and published by . This book was released on 1993 with total page 936 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Positron Annihilation on Atoms and Molecules written by Koji Iwata and published by . This book was released on 1997 with total page 406 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 The Origin of the Galactic 511 KeV Positron Annihilation Emission Morphology written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The origin of the Galactic 511 keV positron annihilation emission morphology.
Download or read book Physics Briefs written by and published by . This book was released on 1994 with total page 1118 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Detection of the 511 KeV Positron Annihilation Line with the Compton Spectrometer and Imager written by Carolyn Kierans and published by . This book was released on 2018 with total page 273 pages. Available in PDF, EPUB and Kindle. Book excerpt: The signature of positron annihilation, namely the 511~keV $\gamma$-ray line, was first detected coming from the direction of the Galactic center in the 1970's, but the source of Galactic positrons still remains a puzzle. The measured flux of the annihilation corresponds to an intense steady source of positron production, with an annihilation rate of $\sim$10$^{43}$~e$^+$/s. Spatially, the 511~keV intensity is strongest in the Galactic center region, with an additional component that is consistent with the Galactic disk; however, the unique morphology is not well constrained. The Compton Spectrometer and Imager (COSI) is a balloon-borne soft $\gamma$-ray (0.2--5~MeV) telescope designed to perform wide-field imaging and high-resolution spectroscopy, with a goal of furthering our understanding of Galactic positrons. COSI employs a compact Compton telescope design, using 12 cross-strip germanium detectors to track the trajectory of incident photons, where position and energy deposits from Compton interactions allow for a reconstruction of the source sky position and significant background reduction. COSI had a record-breaking 46-day balloon flight from Wanaka, New Zealand, in May--July 2016, and here we report on the detection and analyses of the 511~keV emission from those observations. To isolate the Galactic positron annihilation emission, we have developed a background subtraction technique utilizing the COMPTEL Data Space. With this new method, we find a 7.2~$\sigma$ detection of the 511~\keV line and a broader spatial distribution of the emission than has been previously reported.
Download or read book Reports on Astronomy written by Jacqueline Bergeron and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 603 pages. Available in PDF, EPUB and Kindle. Book excerpt: IAU Transactions are published as a volume corresponding to each General Assembly. Volume A is produced prior to the Assembly and contains Reports on Astronomy, prepared by each Commission President. The intention is to summarize the astronomical results that have affected the work of the Commission since the production of the previous Reports up to a time which is about one year prior to the General Assembly. Volume B is produced after the Assembly and contains accounts of Commission Meetings which were held, together with other material. The reports included in the present volume range from outline summaries to lengthy compilations and references. Most reports are in English.
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 Government Reports Announcements Index written by and published by . This book was released on 1992 with total page 1266 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transactions of the International Astronomical Union written by International Astronomical Union and published by . This book was released on 1994 with total page 624 pages. Available in PDF, EPUB and Kindle. Book excerpt:
