A twelve detector coincidence spectrometer for on-line and off-line measurements of nuclear g-factors

g-factors of the ground state rotational band of158Dy

“…In spite of the limited energy resolution of the BaF2 detectors this can be done with sufficient accuracy by use of the directly measured Ey, -E~= coincidence matrices. Figure 2 shows as an example one out of the 66 coincidence matrices which are measured simultaneously for all two-detector combinations of the angular arrangement of twelve detectors [ 1,8]. A few favourable circumstances allow to derive the two g-factors with negligibly small systematic errors: a) g(2+): The 218-99keV correlation used for the measurement contains a weak disturbing Compton background of high energy lines under the 99 keV peak.…”

“…They were mounted inside the room temperature access in the centre of the superconducting magnet of the twelve detector apparatus [ 1 ]2.…”

“…In the target holder, see [1], the Gd foil is mounted in an aluminium frame and cooled to 4 K by direct mechanical contact with the liquid helium capsule of the superconducting magnet. The magnet was powered to the maximum field of 4.5 T. In the geometry of our twelve detector apparatus [1,8] the direction of the magnetic field is parallel to the beam axis and therefore perpendicular to the surface of the foil. For a complete magnetization of the Gd foil the external field must be considerably larger than the saturation magnetization of Gd (Bsat(Gd)~2.5 T) in order to overcome the demagneti-zation field.…”

“…We have started a new systematic investigation by online and off-line IPAC measurements with our twelve detector apparatus [ 1 ]. We reach with this system such a high statistical accuracy that for the first time quite accurate on-line y-?J IPAC measurements ofg (I) up to I= 6 or 8 are possible by application of pure static hyperfine fields.…”