• V. Kashikhin, G. Ambrosio, N. Andreev, E. Barzi, R. Bossert, J. DiMarco, V.S. Kashikhin, M.J. Lamm, I. Novitski, P. Schlabach, G. Velev, R. Yamada, A.V. Zlobin
  Fermilab, Batavia, Illinois

High field accelerator magnets are being developed at Fermilab for present and next generation hadron colliders. These magnets are designed for a nominal field of 10^-12 T in the magnet bore of 40-50 mm and an operating temperature of 4.5 K. To achieve these design parameters, a new, high-performance Nb3Sn superconducting strand is used. Four short Nb3Sn dipole models of the same design based on a single-bore cos-theta coil and a cold iron yoke have been fabricated and tested at Fermilab. Their field quality was measured at room temperature during magnet fabrication and at helium temperature. This paper reports the results of warm and cold magnetic measurements. The systematic geometrical harmonics and their RMS spread due to cross-section imperfections, the coil magnetization effects caused by persistent currents in superconductor and eddy current in the cable, the "snap-back" effect at injection and the iron saturation effect at high fields are presented and compared with theoretical predictions.