I have a query assigned with the formation of elements in particle accelerators. We know that two hydrogen atoms for example fuse under extreme conditions to give a helium atom to release a lot of energy. But then, why is it that fusion of much heavier elements in a particle accelerator occurs under a relatively achievable condition and that too without it being as much exothermic as the former??
Please forgive my lack of knowledge but I'd appreciate it if someone could clarify this for me.