When an accelerated ion strikes a neutral atom at a pressure of 10m Hg in a discharge tube then why does the ionization of the gas present in the discharge tube further increases ? I meant , What happens when a charged accelerated particle strikes a neutral particle ? 1) Does the neutral...

I remember reading a while back about a particle that had to spin twice before it looked the same and it blew my mind but I forgot the name of this particle. I think its something like a 1/2 turn particle. Any ideas what this might be?

So if you have an alpha particle accelerated to 23.1 MeV per particle. How do you convert it to find the energy in kJ/mole?