TGRS Measurements of the Positron Annihilation Spectrum from the Galactic Center

M. J. Harris

B. J. Teegarden, T. L. Cline, N. Gehrels

D. M. Palmer

R. Ramaty

H. Seifert


The TGRS experiment on board the Wind spacecraft includes a Ge detector with very high resolution (3-4 keV FWHM) at energies around 511 keV. To take advantage of WIND 's fixed pointing at the south ecliptic pole, and its 3 s rotational stabilization period, TGRS also includes a Pb occulter fixed on the spacecraft body, subtending an arc of 90 deg along the ecliptic plane. Spectra of the Galactic center region, identified by this occultation method, have been accumulated since 1994 November. In this paper we present updated results for the Galactic center positron annihilation line and continuum from analysis of these occulted spectra. The quantities that can be extracted from the data include the intensity, width, energy and variability of the line, the positronium fraction, and limited information about the spatial distribution of the line.

File translated from TEX by TTH, version 2.32.
On 16 Jul 1999, 09:18.