The US Department of Energy has approved a US$1-billion upgrade to the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory in Tennessee.

The SNS generates neutrons by firing a high-energy beam of protons at a mercury target. The neutrons are used to probe the structures of materials ranging from proteins to superconducting ceramics. The existing SNS facility, completed in 2006, currently feeds neutrons to 10 instruments used by about 1,000 scientists and engineers last year. The addition of a second target will allow for up to 24 more instruments, fed by long pulses of slower-moving cold neutrons, which can be used to study larger molecules such as polymers.

Conceptual design work on the upgrade can now begin, with construction expected to finish no earlier than 2020.