Measurements of theg-factor ratio of the first 3− and 5− states in40Ca and the lifetime of the 5− state

[Theg-factor ratio of the first excited 3^? and 5^? states in⁴⁰Ca was measured to beg ₃/g ₅=1.01(10) employing the implantation perturbed angular correlation technique. The static hyperfine fields (SF) in Fe and Gd hosts were used. In addition the lifetime of the 5^? state was measured to be τ=426(7)ps. The values of the SF in Gd and Fe hosts were deduced and compared with systematics in this element region.     

Plunger measurements on highly stripped O-ions as tool for detecting electron polarization on emergence from thin ferromagnetic layers

From hyperfine interaction studles on free single electron¹⁶O(3⁻) ions. in a time differential mode using the recoil distance technique. It is shown that these ions are polarized when emerging from magnetized thin layers of Fe. The observed degree of polarization , however, is smaller than expected from transient field measurements.     

New aspect in transient magnetic fields using heavy ion beams

Transient field precessions have been measured with the first excited 2 ₁ ⁺ -state as probe for ions of²⁸Si traversing Fe at v_ion?1v₀ and 13v₀(v₀=c/137) and⁶²Ni being stopped in Fe. The degree of polarization deduced for the Si ions, p_1s=0.19(6), is consistent with low-velocity data. There is clear evidence that the field strength is attenuated by heavy ion beams. For the⁶²Ni(2 ₁ ⁺ ) state at 1.173 MeV a g-factor value of g=0.34(7) was obtained in good agreement with a previous result.     

Measurements of lifetime andg-factor of the 32S(4 1 + ) state at 4.459 MeV

Precessions of the very short-lived 2 ₁ ⁺ - and 4 ₁ ⁺ -states in³²S have been measured using the transient field technique. The deducedg-factor of the 4 ₁ ⁺ -state g=+0.40(15) agrees with the known value of the 2 ₁ ⁺ -state and with theoretical predictions. In addition, the lifetimes of both states were redetermined and are consistent with previous results.     

Experimental tests for detecting spin polarization pick-up of single-electron19F-ions on emergence from magnetized iron

A new method to detect polarization pick-up by ions emerging from thin polarized ferromagnetic layers has been tested. The applied technique consists in the observation of attenuated-angular correlations and atomic spin precessions for single-electron ions recoiling through vacuum in weak transverse magnetic fields. The Coulomb-excited¹⁹F(5/2⁺) state at 197 keV was used as probe. The experimental concept is described and the expected effects are discussed using the perturbed angular correlation formalism for polarized hyperfine interactions.     

Dielectric properties of beryllia ceramics in the near-millimeter wavelength range

We report the refractive indices and absorption coefficients for four beryllia (BeO) ceramic samples. These dielectric properties have been measured over the range from 4 to 18 cm^–1 by use of a Michelson interferometer. The index n, follows the linear relationship n=0.6517 cm³/g×+0.7130 with density, , over the range 2.8<<3.0 g/cm³.     

TransientK-shell hyperfine fields and deduced polarizations for single-electron C and O ions in different ferromagnets

Effective transient magnetic fields have been measured for single-electron carbon and oxygen ions traversing ferromagnetic Ni and Gd hosts, respectively. The deduced values ofK-shell polarization are well explained considering spin exchange scattering as a dominant mode of polarization.     

Large electron polarization of H-like20Ne-ions traversing gd foils at very high velocities

It is shown that transient magnetic fields in Gd-host for²⁰Ne ions at a mean velocity of 12.5v₀(v₀=c/137), considerably beyond the Bohr velocity of 1s electrons of Ne ions (v_1s=10v₀), are dominated by the Fermi contact field of these electrons. The first excited 2⁺-state of²Ne was used as probe. The derived value for the mean degree of polarization p_1s=0.32(13), is surprisingly large, though still consistent with values obtained at lower velocities. Present calculations of spin exchange cross sections severely underestimate the observed polarization at this high velocity.The authors are grateful to the operating staff of the UNILAC for providing excellent beam conditions. They also thank Dr. P. Maier-Komor for preparing the delicate targets. Support by the BMFT is acknowledged.