. . "Beta particles are stopped by a few millimetres of aluminium but can travel further than alpha particles and are therefore have a less strong ionising effect. This means they knock electrons out of air molecules forming positively charged air molecules."@en . . "Beta particle"@en . "Beta particles are stopped by a few millimetres of aluminium but can travel further than alpha particles and are therefore have a less strong ionising effect. This means they knock electrons out of air molecules forming positively charged air molecules."@en .