Simplify the following text for a Grade 5 native English-speaking person.
Original: Alpha particles ( named after and denoted by the first letter in the Greek alphabet , Î ) consist of two protons and two neutrons bound together into a particle identical to a helium nucleus , which is produced in the process of alpha decay .
Simplified: An alpha particle is made up of two protons and two neutrons . It is a kind of helium .