J Claes

Formulation of angular correlation and distribution experiments in the presence of a texturized hyperfine interaction

This report deals with the interpretation of experimental results on hyperfine interaction (h.f.i.) detected by nuclear radiation, in cases where the interaction has neither a unique nor a random orientation. A formulation has been drawn up to derive from such experiments (angular correlation or nuclear orientation) the appropriate components of the h.f.i. orientational distribution. We expand the so-called texture distribution function by using the Wigner rotation matrices and defining the texture components. Some symmetries in these components are discussed together with features imposed by the crystal symmetry of the host lattice. We show that the angular distribution of nuclear radiation can be developed as a linear combination in the texture components. The detection geometry selects which components are observed, what allows to design experiments such that a differentiation between texture models is possible. Finally some tables illustrate the general applicability of the present formulation to any kind of texture.

The electric field gradient at iodine impurities in zinc and cadmium

The electric quadrupole interaction at iodine implanted in zinc and cadmium single crystals is investigated, using the β-γ perturbed angular correlation technique. The results show that the implanted129Te and132Te isotopes occupy two well-defined sites, identified by the electric field gradient parameters. One fraction of the impurities is substitutionally implanted, witheqzz=−1.49(9)1018 and −1.58(15)1018V/cm2, in Zn and Cd respectively. The other fraction is identified as an impurity-divacancy configuration with |eqzz|=3.81(8)1018V/cm2; η=0.72(4) for Zn and |eqzz|=3.55(11)1018V/cm2; η=0.53(13) for Cd. The electronic enhancement in the electric fieldgradient at the substitutional site equalsK=−0.66 and −0.56 respectively and follows the empirical trend ofK versus the impurity valence for the s-p elements in Zinc.

Nuclear moments in the doubly odd 132I isotope

Abstract The nuclear moments of the 50 keV, I = 3 + and 278 keV, I = 1 + states in 132 I are measured by perturbed angular correlation techniques, using the quadrupole interaction of iodine in a tellurium matrix and a combined magnetic and electric interaction of iodine in nickel. The results are | Q (3 + )| = 0.23±0.07 b and Q (1 + ) = −0.170±0.006 b and μ (1 + ) = +1.88±0.11 μ N , confirming a [(π g 7 2 )(ν d 3 2 ) −1 ] and a [(π d 5 2 )(ν d 3 2 ) −1 ] configuration for the states concerned.

Dependence of the TDPAC spectra on teh orientation of the principal axis system of the electric field gradient

Analytical expressions are derived, which give the frequency amplitudes of a time differential perturbed angular correlation pattern, as a function of the orientation angles of the principal axis system of the electric field gradient tensor. We show, that allowed β-γ TDPAC experiments are anisotropic only if the main axis of the electric field gradient forms a unique angle with the crystal symmetry axis or if the multiple crystallographically equivalent directions in a cubic crystal are unequally populated.

Quadrupole interactions at different probe ions implanted in nickel single crystals as observed by β-γ TDPAC

AbstractWe discuss specific features of those angular correlation experiments sensitive to the nuclear polarization in the intermediate state and investigate, in view of radiation damage studies, the interest of using allowed as well as first-forbidden β-decay as the primary radiation in a TDPAC cascade. The description of the technique is illustrated by experiments on the samples

Spatial anisotropy of xenon-defect configurations in cubic single crytals

^{129} \mathop {Te}\limits^ \to \underline {Ni} , ^{132} \mathop {Te}\limits^ \to \underline {Ni} , ^{111} \mathop {Ag}\limits^ \to \underline {Ni}

Electric-field gradient and the temperature-variation on cd-111 in re and zr hcp metal hosts

and