Final answer:
The largest particle accelerator before the Large Hadron Collider was the Stanford Linear Accelerator Center (SLAC).
Step-by-step explanation:
The largest particle accelerator before the Large Hadron Collider was the Stanford Linear Accelerator Center (SLAC). SLAC was a linear accelerator that accelerated particles up to 50 GeV. It was used to accelerate electrons and positrons to high energies.