Interaction chamber (IMAGE) Imperial College London Caption This photo shows you the outside of the vacuum chamber which is completely surrounded by painted lead bricks. The lead is for radiation protection and the metal frame allows the lead walls to be rolled in and out of the way to allow access to the chamber. They're painted because lead is highly toxic and so painting them prevents them generating harmful lead dust. Credit Rob Shalloo Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.