Does particles have particles?

An electron or a positron.

You could choose any element to use in a particle accelerator, but the most commonly-used one is Hydrogen- it's the smallest, the lightest, and most abundant of all elements.

Betaminus (β-) particles are the same as electrons .Betaplus (β+) particles are the same a positrons

Particles inside a solid are packed tightly into neat rows, those that are in a gas are floating around an moving randomly and in a liquid they are not as tightly packed and aren't in rows