The track of one of these particles is the spur in the spur model of the formation of a larger structure containing this entity. The FERMI and ATIC projects have detected an anomalous excess of these particles in the GeV range. The creation of these particles from one source causes that source to release 1.27 MeV photons. This is one half of a duo named for Dalitz. These particles are produced from sodium 22. A form of spectroscopy that determines their lifetime looks for the 511 keV photons that indicate their destruction. These particles are 
The track of one of these particles is the spur in the spur model of the formation of a larger structure containing this entity. The FERMI and ATIC projects have detected an anomalous excess of these particles in the GeV range. The creation of these particles from one source causes that source to release 1.27 MeV photons. This is one half of a duo named for Dalitz. These particles are produced from sodium 22. A form of spectroscopy that determines their lifetime looks for the 511 keV photons that indicate their destruction. These particles are produced when a gamma ray creates an electron and one of them in pair production. For 10 points, name these spin 1/2 positively charged particles that are the antiparticles of electrons.
The track of one of these particles is the spur in the spur model of the formation of a larger structure containing this entity.
Positron [accept anti-electron before "electron," do not accept or prompt on just "electron"]