Differential cross sections for ${}_{}{}^{92,94,96}{}_{}{}^{}\mathrm{Zr}(d, p)$ at 33.3 MeV were measured in 5° increments from 12.5 to 42.5° lab. The resolution was about 25 keV full width at half maximum. Many levels were characterized which were not reported or were improperly identified in previous neutron-transfer studies. ($\alpha$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$) spectra with 55-keV resolution were obtained at 15 and 20° for each target with 65.7-MeV $\alpha$ particles. The data were compared with distorted-wave calculations. With a few exceptions, consistent spectroscopic factors were obtained from the ($d, p$) and ($\alpha$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$) reactions. Sums of spectroscopic factors and centers of gravity are presented for levels assigned to $d_{\frac{5}{2}}$, $s_{\frac{1}{2}}$, $d_{\frac{3}{2}}$, $g_{\frac{7}{2}}$, and $h_{\frac{11}{2}}$ configurations in ${}_{}{}^{93}{}_{}{}^{}\mathrm{Zr}$ and ${}_{}{}^{95}{}_{}{}^{}\mathrm{Zr}$. Except for the $h_{\frac{11}{2}}$ states, these sums are in good agreement with sum-rule predictions. Only ∼50% of the expected $h_{\frac{11}{2}}$ strength was observed; the remainder appears to be highly fragmented and at excitation energies above 5 MeV.

The two-center shell model for fission has been generalized to include asymmetric deformations. The calculation of the potential energy involves four independent shape variables, where only two were required in the symmetric calculations. Potential energy calculations have been carried out for ${}_{}{}^{202}{}_{}{}^{}\mathrm{Pb}$, ${}_{}{}^{210}{}_{}{}^{}\mathrm{Po}$, ${}_{}{}^{236}{}_{}{}^{}\mathrm{U}$, ${}_{}{}^{248}{}_{}{}^{}\mathrm{Cm}$, ${}_{}{}^{252}{}_{}{}^{}\mathrm{Fm}$, and ${}_{}{}^{264}{}_{}{}^{}\mathrm{Fm}$. Asymmetric fission is found to be energetically preferred in ${}_{}{}^{236}{}_{}{}^{}\mathrm{U}$, ${}_{}{}^{248}{}_{}{}^{}\mathrm{Cm}$, and ${}_{}{}^{252}{}_{}{}^{}\mathrm{Fm}$; and symmetric fission is preferred in ${}_{}{}^{202}{}_{}{}^{}\mathrm{Pb}$, ${}_{}{}^{210}{}_{}{}^{}\mathrm{Po}$, ${}_{}{}^{258}{}_{}{}^{}\mathrm{Fm}$, and ${}_{}{}^{264}{}_{}{}^{}\mathrm{Fm}$. Two of these nuclei, namely ${}_{}{}^{236}{}_{}{}^{}\mathrm{U}$ and ${}_{}{}^{210}{}_{}{}^{}\mathrm{Po}$, have been studied in detail. It is seen that the asymmetry in ${}_{}{}^{236}{}_{}{}^{}\mathrm{U}$ remains almost constant from the second saddle to scission, whereas in ${}_{}{}^{210}{}_{}{}^{}\mathrm{Po}$ (and also in ${}_{}{}^{202}{}_{}{}^{}\mathrm{Pb}$), the preferred shape changes from asymmetry in the region of the second saddle to symmetry in the region of scission. The results for Fm isotopes indicate that there is a transition from asymmetric fission in the lighter Fm isotopes to symmetric fission in the heavier Fm isotopes. The preference for symmetric mass division in ${}_{}{}^{264}{}_{}{}^{}\mathrm{Fm}$ is very strong, since two double-magic ${}_{50}{}^{132}{}_{}{}^{}\mathrm{Sn}_{82}^{}{}_{}{}^{}$ fragments are formed at symmetry. In general, the structures which appear in the potential energy surfaces are the results of an interplay between compound-nucleus shell structure, fragment shell structures, and liquid-drop-model energies. Comparisons of our results with experimental observations indicate that the observed mass distribution is correlated with the potential energy surface in the neighborhood of scission.

Neutron transmission and total neutron-capture yields were measured using the time-of-flight technique at the Oak Ridge electron linear accelerator facility using enriched samples of ${}_{}{}^{92}{}_{}{}^{}\mathrm{Mo}$. A total of 42 resonances were observed for neutron energies less than 32 keV. 12 are assigned to $s$-wave interactions, while 23 are assigned to $p$-wave interactions. The resonant energies, neutron widths, radiation widths, and spins are deduced. The average $s$- and $p$-wave radiation widths are equal to 0.178±0.015 eV and 0.24±0.03 eV, respectively. The $s$-wave neutron strength function is (0.65±0.26)×${10}^{-4\mathrm{}}$, while the $p$-wave strength function is (3.3±1.1)×${10}^{-4\mathrm{}}$.

Electron-positron pairs have been observed in the $\alpha$ decay of ${}_{}{}^{241}{}_{}{}^{}\mathrm{Am}$. A result of (3.1±0.6) × ${10}^{-9\mathrm{}}$ pairs per $\alpha$ decay was obtained. It is believed that the pairs are due to internal pair production occurring in the $\alpha$-decay process. An approximate calculation, which assumes this production mechanism, is in reasobable agreement with the experimental result.

This paper reports the results of the authors' mass spectroscopic measurements on the masses of the isotopes ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$, ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$, and ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$. Notice is taken of recently reported mass-difference measurements and $Q$-value measurements, and a least-squares process is used to construct a new mass table for the heavy isotopes. This table differs from Wapstra's 1967 table in two major respects: (1) For most isotopes with $A>\mathrm{}220\mathrm{}$ the new mass value is lower than the old mass value by 20-25 μu, or roughly 1½ times the quoted error in the 1967 table. (2) As a result of the new measurements, the uncertainty in our knowledge of the masses of most of the heavy isotopes has been reduced by very roughly a factor of 3.

Angular distributions have been measured for $\gamma$ rays emitted following the decays of ${}_{}{}^{187}{}_{}{}^{}\mathrm{W}$ and ${}_{}{}^{185,191,193}{}_{}{}^{}\mathrm{Os}$ nuclei polarized at low temperatures in iron. The decay of polarized spin-½ nuclear levels was found to show isotropic angular distributions to three parts in ${10}^4$, in keeping with angular momentum theory, and purity of the accepted nuclear spin values. The magnitudes of the magnetic moments of the ${}_{}{}^{187}{}_{}{}^{}\mathrm{W}$ and ${}_{}{}^{193}{}_{}{}^{}\mathrm{Os}$ ground states have been deduced to be $(0.688\mathrm{}\pm 0.021){\mu }_N$ and $(1.30\mathrm{}\pm 0.19){\mu }_N$, respectively, assuming saturation of the hyperfine field at the nucleus; the magnitude of the magnetic moment of the ${}_{}{}^{191}{}_{}{}^{}\mathrm{Ir}$ 171-keV level has been similarly deduced to be $(3.27\mathrm{}\pm 0.12){\mu }_N$, based in part on the observation that the nuclear spin-lattice relaxation time associated with decays from that level is less than 0.1 sec. $\frac{E2\mathrm{}}{M1\mathrm{}}$ multipole mixing ratios have been deduced for a number of ${}_{}{}^{187}{}_{}{}^{}\mathrm{Re}$ and ${}_{}{}^{193}{}_{}{}^{}\mathrm{Ir}$ $\gamma$ rays, and the multipole characters of several of the $\beta$ radiations emitted by ${}_{}{}^{187}{}_{}{}^{}\mathrm{W}$ and ${}_{}{}^{193}{}_{}{}^{}\mathrm{Os}$ have been obtained; these multipolarities are discussed in terms of the nuclear structure. The use of polarized ${}_{}{}^{191}{}_{}{}^{}\mathrm{Os}$ as an absolute $\gamma$-ray anisotropy thermometer is discussed.

A large shielded liquid-scintillation detector operating 3240 m below the surface of the earth was used to detect $\gamma$ rays from the spontaneous fission of a ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ source. In an energy range from 8 to 20 MeV, the derived spectrum is: $N\left(E\right)=(6.99\mathrm{}\pm 0.60)\times {10}^{-1\mathrm{}}{e}^{-\frac{E}{1.41\pm 0.12}}$ photons ${\mathrm{fission}}^{-1\mathrm{}}$ Me${\mathrm{V}}^{-1\mathrm{}}$.

$\gamma$ rays associated with the spontaneous fission of ${}_{}{}^{252}{}_{}{}^{}\mathrm{Cf}$ have been observed in the energy range 10-16 MeV using two 7.6-cm- by 29.2-cm-diam NaI(T1) crystals in coincidence with two solid-state fission counters. Evidence is presented for a $\gamma$ ray multiplicity of 2 implying the presence of a collective mode of fragment deexcitation. The fission-fragment-mass-ratio distribution shows an increase in the number of symmetric fissions when the detected $\gamma$ energy exceeds 14 MeV. It is suggested that deexcitation of the fragments by the giant dipole resonance may be responsible for the presence of the high-energy $\gamma$ rays.

This experiment with a molecular-beam electric-resonance spectrometer determined the hyperfine structure of indium fluoride, ${}_{}{}^{115}{}_{}{}^{}\mathrm{In}$${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$, to an accuracy of 1 part in ${10}^6$. The experiment was an attempt to observe the interaction of a nuclear electric hexadecapole moment of ${}_{}{}^{115}{}_{}{}^{}\mathrm{In}$ that a simple order of magnitude calculation and a previous experiment showed might barely be observable. Although a hexadecapole interaction energy larger than 500 Hz could have been detected, no evidence of the interaction was found. To understand this result, the electric hexadecapole moment was calculated on the basis of a model in which the nuclear electric charge density was assumed to be uniform within a surface defined by $\mathcal{r}(\theta , \phi )=R_0[1+{\beta }_2{P}_2(cos\theta )+{\beta }_4{P}_4(cos\theta \left)\right]$, where ${\beta }_2$ and ${\beta }_4$ are taken to have the same values as the corresponding parameters for the nuclear potential. The value of the hexadecapole interaction energy in ${}_{}{}^{115}{}_{}{}^{}\mathrm{In}$${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ predicted by the model is 10 Hz, well below the limit of detectability with the spectrometer employed in this experiment.

Independent and cumulative yields have been measured for eight $A=131\mathrm{}$ nuclides formed in the interaction of ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ with 11.5-GeV protons. A good fit to the cross sections was obtained with a charge dispersion consisting of two overlapping Gaussians peaking at $Z=52.2\mathrm{} \mathrm{and} 56.5$. The neutron-excessive curve accounts for about 40% of the total isobaric yield of 23.3±0.4 mb. Thick-target recoil properties were determined for all the nuclides. The recoil ranges are characteristic of fission fragments for ${}_{}{}^{131}{}_{}{}^{}\mathrm{Sb}$ through ${}_{}{}^{131}{}_{}{}^{}\mathrm{Cs}$ but decrease by a factor of 2 between ${}_{}{}^{131}{}_{}{}^{}\mathrm{Cs}$ and ${}_{}{}^{131}{}_{}{}^{}\mathrm{La}$. This decrease occurs some two $Z$ units beyond the minimum between the two humps in the charge dispersion. The deposition energies derived from the recoil data exhibit a similar trend as the ranges, increasing in the manner expected for fission products up to barium but not beyond. The transformation of isotopic to isobaric yield distributions is considered and it is concluded that the use of $\frac{N}{Z}$ as the composition variable gives the best agreement with experiment.

In this third paper in a series in which the characteristics of nuclear fragments produced in the interaction of 5-GeV protons with Ag and U targets were studied by means of $\frac{\mathrm{dE}}{dx-E}$ measurements with semiconductor detector telescopes new information was obtained on the energy spectra of light fragments. One set of measurements on fragments from a Ag target involved the use of a two-element telescope incorporating a $\Delta E$ detector as thin as 16 μm. A new algorithm for processing the $\Delta E$ and $E$ data to extract particle identification was developed and the resulting particle spectra showed superior resolution for the elements from Li ($Z=3\mathrm{}$) to S ($Z=16\mathrm{}$). Segments of the energy spectra of each of these elements were measured at 20° and, for many of them, also at 45, 90, 135, and 160° to the beam direction. By use of three-element telescopes and absorbers the high-energy part of the energy spectrum for isotopes of He, Li, Be, B, and C ejected from Ag and U targets was measured at 20°. The measurements extended beyond 300 MeV for ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ and ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ and to 400 MeV for ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$. A distinct high-energy component was found in these cases. The suitability of nuclear evaporation as a description of the emission of the low-energy fragments was tested with two simple theoretical models, one specifying isotropic fragment emission from a moving nucleus at a fixed nuclear temperature and one specifying isotropic fragment emission from a set of moving nuclei with a Maxwellian distribution of excitation energies and forward momenta. The second could describe rather well all the 90° data, provided a Coulomb barrier 0.4 that of the classical tangent-spheres barrier was used. However, the measured intensity in the forward direction was much higher than predicted. Neither evaporation calculation was able to describe the highest-energy part of the spectra, and the conclusion was drawn that these particles must be produced in the initial high-energy cascade.

${}_{}{}^{235}{}_{}{}^{}\mathrm{Pu}$ was produced by the bombardment of ${}_{}{}^{233}{}_{}{}^{}\mathrm{U}$ with 30-MeV $\alpha$ particles and its decay was studied by $\gamma$-ray spectroscopy after a chemical separation. This isotope decays predominantly by electron capture with a half-life of 25.6 min. Energies and intensities of 15 $\gamma$ rays have been determined. An extended decay scheme is proposed and electron-capture branching intensities are given.

Levels in ${}_{}{}^{102}{}_{}{}^{}\mathrm{Pd}$ have been investigated by utilizing the ${}_{}{}^{99}{}_{}{}^{}\mathrm{Ru}(\alpha , n; \gamma ){}_{}{}^{102}{}_{}{}^{}\mathrm{Pd}$ reaction. The basic measurements were $\gamma$-ray excitation functions, angular distributions, and $\gamma -\gamma$ coincidences. All $\gamma$-ray measurements were performed with Ge(Li) detectors. The excitation functions were used to identify ${}_{}{}^{102}{}_{}{}^{}\mathrm{Pd}$ $\gamma$ rays, and the coincidence measurements were used to construct a level scheme. Nuclear spins have been inferred from analysis of the angular distributions. The proposed level scheme contains 24 levels; the dominant $\gamma$-ray cascade connects states of spin $0^{+}$, $2^{+}$, $4^{+}$, $6^{+}$, $8^{+}$, and ${10}^{+}$.

A thick target time-of-flight technique has been used to measure near-threshold neutrons from the ${}_{}{}^{65}{}_{}{}^{}\mathrm{Cu}(p, n){}_{}{}^{65}{}_{}{}^{}\mathrm{Zn}$ reaction. The neutron yield near threshold is dominated by a narrow $2^{-}$ or $3^{-}$ ${}_{}{}^{66}{}_{}{}^{}\mathrm{Zn}$ resonance 148 eV above the 2.17-MeV reaction threshold. The c.m. angular distribution of resonance neutrons is isotropic to within 10%. Neutrons from this resonance lie within a forward cone of half angle 32° and have laboratory energies of 1180.9±4.6 and 107.6±0.6 eV for 0 and 180° c.m. angles, respectively. These energies, when combined with the known masses and reaction $Q$ value, indicate a velocity decrease of 0.7% for the recoiling compound system before neutron decay. The product of the peak cross section and resonance width is 600±50 mb eV, and the width is between 2 and 10 eV. Detailed balance predicts a ${}_{}{}^{65}{}_{}{}^{}\mathrm{Zn}(n, p){}_{}{}^{65}{}_{}{}^{}\mathrm{Cu}$ cross section on the order of 1000 b at 144-eV neutron energy.

Thermal equilibrium nuclear orientation was employed to orient nuclei of ${}_{}{}^{196}{}_{}{}^{}\mathrm{Au}$, ${}_{}{}^{198}{}_{}{}^{}\mathrm{Au}$, and ${}_{}{}^{200m}{}_{}{}^{}\mathrm{Au}$ as dilute impurities in nickel and iron at temperatures down to 4 mK. The degree of nuclear orientation was determined from the anistropy of $\gamma$ radiation emitted from the oriented nuclei. For $\mathrm{N}\mathrm{i}\left({}_{}{}^{200m}{}_{}{}^{}\mathrm{Au}\right)$ both the magnetic hyperfine interaction $\left|\mu H\right|=(7.65\mathrm{}\pm 0.30)\times {10}^{-18\mathrm{}}$ erg and the magnetic hyperfine splitting $\left|\frac{\mu H}{I}\right|=(6.473\mathrm{}\pm 0.012)\times {10}^{-19\mathrm{}}$ erg were determined from an analysis of the temperature dependence of $\gamma$-ray anisotropies and by nuclear magnetic resonance on oriented nuclei (NMR/ON), respectively. As a result the spin $I$ and the magnetic moment $\mu$ of the isomeric state could be derived as $I^{\pi }={12}^{\mathrm{}(-)\mathrm{}}$ and $\mu \left({12}^{-}\right)=\{+\}\left\{\mathrm{}\right(-\left)\mathrm{}\right\}(6.10\mathrm{}\pm 0.20){\mu }_N$. From the measured anisotropies of five $\gamma$ rays originating from the ${\beta }^{-}$ decay of ${}_{}{}^{200m}{}_{}{}^{}\mathrm{Au}$, spins and multipolarities could be assigned in the ${}_{}{}^{200}{}_{}{}^{}\mathrm{Hg}$ decay scheme. Nuclear magnetic resonance was also observed on oriented ${}_{}{}^{196}{}_{}{}^{}\mathrm{Au}$ and ${}_{}{}^{198}{}_{}{}^{}\mathrm{Au}$ in nickel at frequencies of 58.3±0.4 MHz and 58.5±0.4 MHz, respectively. The hyperfine interaction for Ni(${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$), measured previously by spin echo, and our result for Ni(${}_{}{}^{196,198}{}_{}{}^{}\mathrm{Au}$) agree with the known atomic hyperfine anomalies between ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ and ${}_{}{}^{196,198}{}_{}{}^{}\mathrm{Au}$ only if the hyperfine field is assumed to have a noncontact contribution. For Ni(${}_{}{}^{196,198}{}_{}{}^{}\mathrm{Au}$) with $H_{\mathrm{hf}}=(-)260.8\pm 1.3$ kOe, the contact part is then found to be $H_{\mathrm{c}}=-367\mathrm{}\pm 70$ kOe, with the noncontact contribution amounting to $H_{\mathrm{nc}}=+106\mathrm{}\pm 70$ kOe. The angular distributions of several $\gamma$ rays are in excellent agreement with a decay scheme proposed by Cunnane et al., in which they found negative-parity levels of spins 5, 7, 9, and 11 at energies of 1852, 1963, 2144, and 2642 keV, respectively, in ${}_{}{}^{200}{}_{}{}^{}\mathrm{Hg}$.

The decay of ${}_{}{}^{173}{}_{}{}^{}\mathrm{Ta}$ was studied using high resolution Ge(Li), Si(Li), and Si surface-barrier detectors in singles and coincidence modes. The ${}_{}{}^{173}{}_{}{}^{}\mathrm{Ta}$ activity was produced via the reaction ${}_{}{}^{165}{}_{}{}^{}\mathrm{Ho}({}_{}{}^{12}{}_{}{}^{}\mathrm{C}, 4n){}_{}{}^{173}{}_{}{}^{}\mathrm{Ta}$, at a carbon beam energy of 6.3-6.9 MeV per nucleon. All spectra were obtained from chemically separated Ta sources. Besides the previously known energy levels of ${}_{}{}^{173}{}_{}{}^{}\mathrm{Hf}$, the following levels in keV were determined: 255.5, 451.9, 508.9, 635.8, 775.5, 785.3, 811.7, 927.5, 942.5, 1020.3, 1111.4, 1127.0, 1192.8, 1248.3, 1450.0, 1574.2, 1655.6, 1667.1, 1694.3, and 2263.3. Rotational bands based on the ${\left(\frac{1}{2}\right)}^{-}\mathrm{}\left[521\right]\mathrm{}$ (g.s.), ${\left(\frac{5}{2}\right)}^{-}\mathrm{}\left[512\right]\mathrm{}$ (107.2 keV), and ${\left(\frac{7}{2}\right)}^{+}\mathrm{}\left[633\right]\mathrm{}$ (197.5 keV) Nilsson states were observed. The half-lives of the ${\left(\frac{5}{2}\right)}^{-}\mathrm{}\left[512\right]\mathrm{}$ and the ${\left(\frac{1}{2}\right)}^{+}\mathrm{}\left[633\right]\mathrm{}$ band heads were determined to be (182±20) nsec and (160±40) nsec, respectively. The probability of the radiative $E1\mathrm{}$ transition between the [633] and [512] band heads was calculated within the framework of Nilsson model including the pairing and Coriolis interactions. From measurement of the ${\beta }^{+}$ end-point energy, the mass difference between ${}_{}{}^{173}{}_{}{}^{}\mathrm{Ta}$ and ${}_{}{}^{173}{}_{}{}^{}\mathrm{Hf}$ was determined to be 3670±200 keV.

Branching ratios to excited nuclear states formed after muon capture have been measured with Ge(Li) detectors. The delayed $\gamma$ rays were observed in studies of muonic ${}_{}{}^{142}{}_{}{}^{}\mathrm{Ce}$, ${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$, ${}_{}{}^{138}{}_{}{}^{}\mathrm{Ba}$, and ${}_{}{}^{120}{}_{}{}^{}\mathrm{Sn}$, using separated isotopes. The resulting isotopes formed indicate at least a 60% probability of neutron emission upon muon capture, with the most likely product resulting from single-neutron emission. No evidence for delayed proton emission with a probability higher than 2% was found. Using our more precise energies for the observed nuclear transitions, we present revised energy levels schemes for ${}_{}{}^{141}{}_{}{}^{}\mathrm{La}$, ${}_{}{}^{139}{}_{}{}^{}\mathrm{La}$, ${}_{}{}^{137}{}_{}{}^{}\mathrm{Cs}$, and ${}_{}{}^{119}{}_{}{}^{}\mathrm{In}$.

A 2.5-min activity previously assigned to ${}_{}{}^{147}{}_{}{}^{}\mathrm{Tb}$ is shown to be 2.20 ± 0.05-min ${}_{}{}^{148}{}_{}{}^{}\mathrm{Tb}$. Levels are proposed in ${}_{}{}^{148}{}_{}{}^{}\mathrm{Gd}$ at 784.48, 1273.31, 1416.35, 1754.96, 1810.90, 2563.8, and 2693.31 keV. The decay of this ${}_{}{}^{148}{}_{}{}^{}\mathrm{Tb}$ activity occurs almost entirely to a single high-lying, high-spin level in ${}_{}{}^{148}{}_{}{}^{}\mathrm{Gd}$. A short-lived ${}_{}{}^{147}{}_{}{}^{}\mathrm{Tb}$ isomer is found to have a half-life of 1.83 ± 0.06 min and prominent $\gamma$ rays of energy 1397.3 and 1798.0 keV.

Coulomb excitation with ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ beams was used to excite, polarize, and implant ${}_{}{}^{180}{}_{}{}^{}\mathrm{Hf}$(2+) in Hf single crystals and ${}_{}{}^{186}{}_{}{}^{}\mathrm{W}$(2+) in Gd single crystals. Particle-$\gamma$ correlations for different crystal orientations were measured. The general features of the perturbed correlations were consistent with the prediction for a static axially symmetric quadrupole interaction in a single crystal, but additional perturbations had to be taken into account to explain the results quantitatively. Special experimental geometries were employed to separate these perturbations. In the ${}_{}{}^{180}{}_{}{}^{}\mathrm{Hf}$ in Hf experiment the sign of the quadrupole interaction could be unambiguously determined as negative using the known polarization of the excited nucleus. In the ${}_{}{}^{186}{}_{}{}^{}\mathrm{W}$ in Gd case unknown perturbation mechanisms reduced the terms linear in the quadrupole interaction frequency to such an extent that the negative sign indicated is less certain. Control experiments with implantation of ${}_{}{}^{186}{}_{}{}^{}\mathrm{W}$ in Cu foils were used to check the experimental technique for systematic errors.

NUCLEAR REACTIONS (HI Coulomb excitation) ${}_{}{}^{186}{}_{}{}^{}\mathrm{W}$, $E\left({}_{}{}^{16}{}_{}{}^{}\mathrm{O}\right)=40\mathrm{}$ MeV, $E\left({}_{}{}^{32}{}_{}{}^{}\mathrm{S}\right)=80\mathrm{}$ MeV, recoil Gd single crystal; measured ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}\gamma \left(\theta \right)$, ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}\gamma \left(\theta \right)$; deduced sign ${}_{}{}^{186}{}_{}{}^{}\mathrm{W}$(2+) quadrupole interaction. ${}_{}{}^{180}{}_{}{}^{}\mathrm{Hf}$, $E\left({}_{}{}^{16}{}_{}{}^{}\mathrm{O}\right)=40\mathrm{}$ MeV, recoil Hf single crystal; measured ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}\gamma \left(\theta \right)$; deduced sign ${}_{}{}^{180}{}_{}{}^{}\mathrm{Hf}$(2+) quadrupole interaction.

Neutron-proton bremsstrahlung calculations predict cross sections integrated over the photon angle, ${\theta }_{\gamma }$, which show rather modest model dependence. However, the predicted photon angular distributions manifest a large model dependence. Unpublished data from a previous experiment were integrated over positive and negative photon angles and the ratio compared with model predictions. The results are that the potential model calculations of Brown and Franklin are favored.