Anti-matter atoms to address anti-gravity question

"The question of whether normal matter's shadowy counterpart anti-matter exerts a kind of "anti-gravity" is set to be answered, according to a new report. 

Normal matter attracts all other matter in the Universe, but it remains unclear if anti-matter attracts or repels it.
A team reporting in Physics Review Letters says it has prepared stable pairs of electrons and their anti-matter particles, positrons.

A beam of these pairs can be used to finally solve the anti-gravity puzzle."