F Nickel
GSI Darmstadt, Germany
Biography
We report on high-precision measurements (relative accuracy 3 10-5) with the high-resolving mass spectrometer FRS at GSI. Bi ions with an energy of 52 GeV traversed a polycrystalline Gd foil of a thickness of 1.2 mm placed in an external magnetic field of 450 Gauss. The energy loss of these ions after passage the foil was measured as a function of the foil temperature T below and above the ferromagnetic Curie temperature TC of about 19 ℃. Further, the macroscopic magnetization M of the used Gd foil was measured as a function of the foil temperature T. The data showed the well-known drop of M approaching TC from lower temperatures. Due to an applied external magnetic field, M does not disappear at TC but exists up-to much higher temperatures reaching 90 ℃. Subtraction of effects due to the thermal expansion and due to a measured asymmetric change of the appearing charge-state distribution of the Bi ions when traversing the Gd foil, the remaining relative energy-loss change (δE/dE)corr increased between 5 ℃ and 98 ℃ from 0 to 1.1(5) 10-3. Between 13 ℃ and 15 ℃ a sharp increase of 0.26(3) 10-3 was observed. A presentation of (δE/dE)corr as a function of the negative logarithm of M, namely –ln M, showed an interesting regular step-wise behavior.