Complex sentence: Using a heavily shielded instrument containing a scintillation detector, built by Dwyer and his students they found that lightning does indeed produce x-rays and that x-ray emission is common for lightning.
Split into simpler sentences: Using a heavily shielded instrument containing a scintillation detector, built by Dwyer and his students. They found that lightning does indeed produce x-rays and that x-ray emission is common for lightning.