March 26, 2008 News

SNS Receives Advanced Superconducting Magnet for Neutron Scattering

Slim Sam during acceptance testing. Shown left to right are Sample Environment Group members Lou Santodonato, Andy Church, and Saad Elorfi.

Scientists often need to apply strong magnetic fields to the materials they study but find that stray magnetic fields wreak havoc with their (and their neighbors') experiments. SNS has taken a big step toward solving this problem by commissioning the world's first actively shielded magnet system specifically designed for neutron scattering.

The new magnet system is known as "Slim SAM" (SAM=shielded asymmetric magnet). It produces a central field of up to 5 tesla (T), which is modest compared with the strongest unshielded neutron magnets of 15 T; however, it has the advantages of very low stray field (less than 0.0005 T at 50 cm away from the sample), an asymmetric field profile optimized for using polarized neutron beams, and a compact size. Slim SAM has passed acceptance tests and is available for the next round of user proposals.

For those who demand both the strongest fields and active shielding, a 16-T actively shielded system has been designed and is under fabrication through a collaboration with the Paul Scherrer Institut, a neutron scattering facility in Villigen, Switzerland. Delivery to SNS is scheduled for 2009.