Algodoo

Neutrons do not survive for long outside of nucleus. Neutrons have a half life of approximately 15 minutes/880 seconds. Here you can see 256 Neutrons decaying into a proton and an electron. (The energy and momentum of both of these particles is not accurate to actual beta- decay. The anti-electron-neutrino isnt included as well. I may create a sim of actual beta- decay with accurate values in the future)