Temperature dependence of dc SQUID magnetometer performances

We report experimental results on temperature dependence of the main characteristics of fully integrated DC SQUID magnetometers realized on niobium technology. At T ¼ 4:2 K the sensor shown a white magnetic field noise spectral density of 2.9 fT/Hz 1/2 . A slow increase of the field noise (about 20%) was observed with increasing temperature up to 5 K, giving a considerable tolerance of the working temperature of niobium magnetometers in some innovative multichannel systems for magnetoencephalography.