Portal:Radiation astronomy/Resource/14

Positrons
"Positron astronomy is 30 years old but remains in its infancy."

"[P]ositron astronomy results ... have been obtained using the INTEGRAL spectrometer SPI". The positrons are not directly observed by the INTEGRAL space telescope, but "the 511 keV positron annihilation emission is".

During solar flares “[s]everal radioactive nuclei that emit positrons are also produced; [which] slow down and annihilate in flight with the emission of two 511 keV photons or form positronium with the emission of either a three gamma continuum (each photon < 511 keV) or two 511 keV photons."