[en] Published in summary form only

No abstract available

[en] A proposed new technique for measuring the sign of the electric field gradient (EFG) is studied by combining the methods of time differential perturbed angular correlation (TDPAC) and Moessbauer spectroscopy. The experiments do not confirm such a suggestion, and recent calculations show that the effect does not exist

No abstract available

[en] 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. (orig.)

[en] The design and construction of a highly stabilized variable-temperature system for Differential Perturbed Angular Correlation measurements is described. In the temperature range from room temperature up to 300⁰C a stability of 0.001⁰C is achieved for short periods (a few hours) and a stability of better than 0.01⁰C for prolonged (typically 30 h) measurements. The temperature gradient over the sample is less than 0.001⁰C. (Auth.)

[en] Data reduction schemes currently used for time differential perturbed angular correlation measurements are evaluated in terms of (i) their relative effectiveness in eliminating irrelevant variables, including single counter efficiencies and spectrum time shifts; and (ii) their effectiveness in putting data in a form that can easily be fitted by theoretical correlation functions. It is pointed out that erroneous conclusions may be derived from improperly reduced data, but that properly analyzed experiments performed at four angles allow a good determination of both the time-dependent and time-independent parts of the correlation function. Correction of data for accidentals, source self-absorption and spectrum livetime differences are discussed. (orig.)

[en] Short communication

[en] The effect of temperature and composition on the electric field gradient in the hcp Cdsub(x)Mg₁sub(-)sub(x) alloys with x = 1.00, 0.96, 0.91, 0.86, 0.50, 0.25 and 0.00 was investigated using the TDPAC method. The quadrupole coupling constant νsub(Q) was measured in the temperature range from 77 K to the corresponding melting point. The temperature dependence of νsub(Q) can be described by the empirical relation νsub(Q)(T) = νsub(Q)(0) x (1 - B x T³sup(/)²) in all cases, except in the CdMg₃ alloy which is known to undergo an order-disorder transition. The quantity νsub(Q) depends linearly on c/a with different slopes at different temperatures. (orig.)

No abstract available