The first antielectron was produced in 1932, and particle accelerators helped scientists create the first antiproton in 1955.    From Wordnik.com.  [Angels, demons and tedium « Anglican Samizdat] Reference

If an electron hits an antielectron and is anihalated, does the wave equation field thing dissapear everywhere simultaneously?.    From Wordnik.com.  [Everything You Ever Wanted to Know About Quantum Mechanics, But Were Afraid to Ask] Reference

The antielectron does not have “anti-mass” in any sense, but looking at the equations you can sort of tilt your head, and if you hold you mouth just right, the antielectron looks like an electron with negative energy moving backward in time.    From Wordnik.com.  [Higgs 101] Reference