  The TUCAN nEDM experiment characterizes the QuSpin Zero-Field Magnetometer
(QZFM) to accurately map residual fields within a large magnetically shielded
room. The magnetometer's intrinsic offset was measured to be within 3 nT and
stable over a period of one year. The response was shown to be within 2 percent
of linearity in the zero-field regime, up to 2 nTpp, and then follows a smooth
dispersion curve. Crosstalk effects induced by multisensor operation were
determined to have a small effect, and inconsequential with a separation above
6 cm. These results enable the QZFM for accurate measurement of DC fields,
increase the operational range of QZFM by a factor of more than an order of
magnitude, and allow for higher efficiency and flexibility by green-lighting
simultaneous operation of multiple QZFMs.
