Magnetometer calibration set-up controlled by nuclear magnetic resonance

In order to calibrate magnetometer sensors in the field range from 2 mT to 150 mT a measuring setup consisting of a water-cooled multilayer solenoid and an NMR-magnetometer of the marginal oscillator type has been developed. With a coil constant of about 20 mT/A the field coil provides a field profile with two flat regions, where the field maxima are equal within 10/sup -5/ and with a distance of more than 40 mm so that both magnetometer readings can simultaneously be compared. The NMR-magnetometer operates with samples having an absorption line width of 2 /spl mu/T with a sample volume of 2 cm/sup 3/ for fields below 20 mT and of 1 cm/sup 3/ for higher fields.