R. A. Naumann

The quadrupole interaction of100Rh in various intermetallic compounds of palladium

The nuclear quadrupole interaction of the 75 keV excited state of100Rh in the ordered intermetallic compounds PdHg, PdPb2 PdSb and PdTe was measured. Using an estimate for the nuclear quadrupole moment of the 75 keV state in100Rh and point ion lattice sums for the lattice electric field gradient (EFG) at the Rh site, the electronic contributionVzzel to the total EFG was derived.Vzzel was found to be correlated with the average valence electron concentration in the compounds studied. In the case of PdPb2, the temperature dependence of the quadrupole interaction was also studied and found not to follow theT3/2 rule which is observed in virtually all pure noncubic metals.

Annealing behavior of In implanted in Si studied by perturbed angular correlation

The perturbed angular correlation technique has been used to study the local environment of 111In implanted to low doses at room temperature into Si as a function of postimplantation annealing temperature. At annealing temperatures corresponding to those where previous electrical measurements have observed reverse annealing behavior, we find evidence for the displacement of In to regions of lattice disorder. This is in contrast to results of ion‐beam channeling experiments on heavy group‐III impurities in Si which have been interpreted to indicate the displacement of the impurity to a unique regular tetrahedral interstitial site.

Temperature dependence study of the quadrupole interaction of111Cd in antimony

A power law dependence has been observed for the temperature dependence of the quadrupole interaction of the 247 keV state of111Cd in antimony, which is similar to that observed for121Sb and123Sb in antimony.

Temperature dependence studies of the electric field gradient at cadmium impurities in heavy rare earth metals

Several of the rare earth metals (Gd, Tb, Dy, Ho and Er) containing111Cd impurities have been studied by the method of time differential perturbed angular correlations (TDPAC) to study electric field gradients. Experiments have been made over a temperature range in which no magnetic interactions are expected. We have observed general correlation patterns whose shapes are temperature dependent. We suggest this provides evidence of a reversible temperature dependent strain or distortion near the impurity atom.

Temperature dependence study of the quadrupole interaction of111Cd in tellurium

A quadrupole interaction corresponding to an interstitial site of axial symmetry has been observed for the 247 keV state of111Cd in tellurium. A possible site is suggested, but little or no temperature dependence has been observed.

Temperature dependence studies of the EFG at111Cd probes located in some intermetallic compounds

The temperature dependences of the electric field gradient (EFG) at111Cd probes in nickel-indium and indium-tellurium intermetallic compounds have been studied by means of the time differential perturbed angular correlation of gamma rays (TDPAC). The room temperature interaction frequencies (e2Qq/h) in each case were determined as In2Te5 (136 MHz), Ni3In (13.8 MHz), NiIn (252 and 337 MHz) (two sites), and Ni2In3 (162 and 266 MHz) (two sites). The TDPAC pattern of111Cd in NiIn did not agree with the previous assignment of the crystal structure. A general discussion of the results related to other temperature dependence studies of the EFG is presented and a general trend is discerned.

Determination of Unique Site Population in Various in Implanted Non-Cubic Metals Using Angular Correlations and the Nuclear Electric Quadrupole Interaction

As part of an investigation of the electric quadrupole interaction (EQI) at impurity nuclei in non-cubic metals1, we have applied the time-differential perturbed-angular correlation (TDPAC) technique2 to the measurement of the EQI at a 111Cd impurity in several hosts. Since in most of the cases studied the 111In parent radioactivity is difficult to introduce in the host lattice by metallurgical means, we prepared all sources by implantation of the 111In activity. As a by-product of the investigation, therefore, we obtained information on the efficiency of the implantation process in providing dilute alloy systems with a large fraction of In impurity atoms at lattice sites which appear unique insofar as the EQI is concerned. This definition of uniqueness implies not only that the impurity site be a specific crystallographic position but also that it sees identical surroundings in the first few shells of neighbors.

Electrical and inertial parameters for Th, U, Pu isotopes

Nuclear properties of eight heavy deformed isotopes have been determined from muonic x-ray hyperfine structure. Trends observed for the electrical and inertial properties are discussed in terms of collective model predictions.

Search for parity and time reversal violations in hindered gamma-decay

We discuss various possibilities to improve the sensitivity of parity and time reversal asymmetry measurements in gamma decaying nuclei. We compare the best known parity violating case180mHf to a similar isotope178mHf. Although the parity violation may not be as large, the 178 isomer is better suited to eliminate experimental systematic problems. We introduce a new detector to enhance the sensitivity of such measurements. Our first experiments indicate applicability of these detectors to P symmetry tests.