FRIB, with support from NSCL, has designed and built a field mapper for use on the magnets of the fragment separator, which will remove contaminants from the beam and collect the desired isotopes for research. The mapper design is the first of its kind for the laboratory. It will scan the magnetic field inside of each magnet to produce a map that can describe its field in three dimensions.

The availability of measured magnetic field maps is important for confirming the magnet’s field quality, for its alignment, and for fragment separator beam-tuning during operation.

The mapper consists of 72 sensors that are evenly spaced in a circular pattern around a ring (see figure). A motorized system passes the ring through the bore as it gets data.

Each sensor measures the magnetic field at a select point. The first design of its kind for the laboratory, past designs have used single rotating probe. Using a circle of fixed probes cuts down on scanning time and keeps the probes in a fixed orbit.