BMSR-2 interior

The single most magnetically-shielded room on Earth is part of Germany’s national standards institute, Physikalisch-Technische Bundesanstalt, (PTB) in Berlin. Known as the BMSR-2, this is a chamber built like a set of Russian dolls out of seven separate shells of magnetically-resistant ‘mu-metal’ – each one thicker than the last – plus a final layer of aluminium. Built on a 6m-thick concrete layer to dampen vibration, it is also fitted with compensating magnetic coils to cancel out any temporary variations in Earth’s magnetic field.
Engineering models of the LISA Pathfinder test masses were tested there in February 2007, with trials repeated for the flight models in July 2009.