SNS Now Home to World’s First Actively Shielded Magnet
for Neutron Scattering
Saad Elorfi and Andrew Church work on Slim SAM.
Neutron scattering scientists often need to apply strong magnetic fields to the materials they study, but the stray magnetic fields generated can wreak havoc on 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, known as Slim SAM (SAM = shielded asymmetric magnet), designed specifically for neutron scattering.
The system 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 also offers new opportunities for the growing number of scientists interested in polarized neutron diffraction. To produce Slim SAM, a team of ORNL scientists, led by Hal Lee, developed detailed magnetic field profile specifications to ensure superior polarized beam performance. They drafted a comprehensive solicitation package, evaluated vendor proposals, and ultimately guided the winning vendor in producing an excellent design.
