Cross sections have been measured for the emission of protons, deuterons, and alpha particles for 15-MeV neutrons on $^{54,56}\mathrm{Fe}$, $^{58,60}\mathrm{Ni}$, $^{50,52}\mathrm{Cr}$, and $^{63,65}\mathrm{Cu}$, as well as on natural iron, nickel, and chromium. A quadrupole spectrometer served to detect particles with energies as low as 1 MeV. For some of the targets, a substantial fraction of the charged-particle spectrum is at energies below the Coulomb barrier. Cross sections and spectra are compared with statistical and pre-equilibrium model predictions.NUCLEAR REACTIONS $^{50,52}\mathrm{Cr}$, Cr, $^{54,56}\mathrm{Fe}$, Fe, $^{58,60}\mathrm{Ni}$, Ni, $^{63,65}\mathrm{Cu}$, ($n$,$p$), ($n$,$d$), ($n$,$\ensuremath{\alpha}$), $E=14.8$ MeV; measured $\ensuremath{\sigma}({E}_{p},\ensuremath{\theta})$, (${E}_{d}$, $\ensuremath{\theta}$), (${E}_{\ensuremath{\alpha}}$, $\ensuremath{\theta}$), enriched and natural targets. Hauser-Feshbach analysis, deduced reaction mechanism.

Systems consisting of two or three magnetic quadropole lenses and detectors were developed for studying charged particles produced by 15 MeV neutrons. The lenses transport the charged particles from a radiator near the neutron source to the detectors located about 2.6 m away in order to reduce the neutron-induced background in the detectors.

A spectrometer to measure neutron-induced charged-particle producing reactions was developed and yields data with greatly improved signal-to-background ratios. It consists of a magnetic quadrupole lens which focusses the charged particles onto a silicon surface barrier detector or a two-detector telescope which is more than 2 meters from the sample being irradiated. The efficiency of the spectrometer is calibrated experimentally and depends only on values for the (n,p) elastic cross section and the stopping power of polyethylene. Further development is underway to replace the surface-barrier ..delta..E counter with a proportional counter of larger area. This detector, combined with a larger E counter (surface barrier) could increase the effective solid angle by a factor of five. The results for (n,xp), (n,xd) and (n,x..cap alpha..) cross sections are summarized for the eight target materials studied so far. Measurements of the charged particle spectra have established that cross sections for production of protons below 2.5 MeV are significant for some targets; in fact protons as low as 800 keV have been detected from aluminum. These low energy protons would be quite difficult to measure with conventional counter telescope spectrometers.

The results of integral precession measurements are reported for 32+ and 52+ excited states in 123,125Te. The measurements were made using the ion implantation perturbed angular correlation technique by recoiling the excited nuclei into polarized iron. The measured mean lifetimes and g-factors are: 123Te (440 keV, 32+) τ = 39±4 ps, g = 0.34 ± 0.06; (505 keV, 52+) τ = 26±3 ps, g = 0.04±0.025; and 125Te(443 keV, 32+) ρ = 27±3.3 ps, g = 0.39±0.06; (464 keV, 52+) g = 0.12±0.04. The results are compared with theoretical predictions.

The ion implantation perturbed angular correlation technique was used to measure the g-factor of the 32− state at 208 keV of 199Hg recoiling into iron. A value g(32−) = 0.35±0.11 was deduced from the data. This result is in agreement with predictions of an extended core excitation model.

Various even-even isotopes of Er, Dy, and Yb have been Coulomb excited to their first ${2}^{+}$ states and implanted into metallic foils of Cu, Al, Ag, and Rh. The attenuation of the subsequent $\ensuremath{\gamma}$-ray angular distribution was measured as a function of temperature and interpreted in terms of a predominant time-dependent magnetic interaction with small admixtures of static and time-dependent electric interactions. Correlation times have been extracted and quantitively compared to the electronic relaxation times (${T}_{2}$) obtained from electron-paramagnetic-resonance measurements of the same impurity-host systems. Comparisons are favorable, provided crystalline-field effects are taken into account.

The ion-implantation perturbed angular correlation technique was used to measure γ-ray angular distributions from the decay of the first (2+) and second (4+) states of even Nd and Sm nuclei recoiled into polarized iron. These data and the results of previous measurements give values of H0 = 2.4±0.3 MOe for H(NdFe), H0 = 2.3±0.2 MOe for H(SmFe) and Htτt = 10.8±8.9 MOe · psec for the transient effect for Sm and Nd nuclei recoil implanted into polarized iron (300°K). The g-factor results for the first (2+) states of 144,146,148Nd and 148,150Sm and for the second (4+) states of 150Nd and 152,154Sm show a rather strong decreasing trend with decreasing neutron number.

The magnetic moments of the ${\frac{7}{2}}^{\ensuremath{-}}$ states at 1.610 MeV in $^{37}\mathrm{Ar}$ and 1.380 MeV in $^{37}\mathrm{K}$ were measured by differential spin-precession methods. The moments, together with the remeasured halflives, are $\ensuremath{\mu}=\ensuremath{-}1.33(5){\ensuremath{\mu}}_{N}$ and ${T}_{\frac{1}{2}}=4.6(2)$ nsec for $^{37}\mathrm{Ar}$, and $\ensuremath{\mu}=+5.2(3){\ensuremath{\mu}}_{N}$ and ${T}_{\frac{1}{2}}=10.5(5)$ nsec for the $^{37}\mathrm{K}$ state. The prediction of the Sachs mirror theorem is shown to hold, and systematic trends in ${\frac{7}{2}}^{\ensuremath{-}}$-state moments of $1{f}_{\frac{7}{2}}$-shell nuclei are examined.

γ-ray transitions of 199Hg were investigated following Coulomb excitation with oxygen ions at different bombarding energies. Angular distributions with and without coincidence with backscattered oxygen ions were measured. Ge(Li) γ-ray spectra were measured in triple coincidence with γ-rays and backscattered particles. A new level is reported at 413.5 keV and assigned a spin of 52−. A spin of 32− is assigned to the level at 403.4 keV instead of the 12− spin previously. B(E2)↑ values measured relative to B(E2)↑ (158.37 keV) = 0.375(17) are 0.248(15), 0.170(20) and 0.099(16) for the 208.3, 403.4 and 413.5 keV transitions, respectively. The measured mixing ratios are —0.65(25) and +0.32(2) for the 208.3 (32− → 12−) and 403.4 (32− → 12−) keV transitions, respectively. The revised decay scheme is presented and discussed. The same experimental techniques were used to Coulomb excite 201Hg. No γ-ray transitions up to an energy of 1000 keV in coincidence with 60 million backscattered particles could be seen when an 85% 201Hg enriched target was bombarded with 33 MeV 16O ions.

The ion implantation perturbed angular correlation technique was used to measure γ-ray angular distributions from the decay of the 545 keV (6+) rotational state of 154Sm recoiled into both copper and polarized iron. The precession angle (ωτ) measured in the polarized iron implantation experiments is consistent with present knowledge of the transient and static magnetic hyperfine fields acting on nuclei recoiled into ferromagnetic hosts. These data and the results of previous measurements give values of Ho = 2.3±0.2 MOe and H1τ1 = 10.7±9.1 MOe · psec for the magnetic hyperfine fields at samarium nuclei recoiled into polarized iron (300°K). The g-factor ratio for the second (4+) and third (6+) excited states of the 154Sm ground state rotational bwand is g6+g4+ = 1.05 ±0.11.

Large volume coaxial Ge(Li) detectors have poor timing properties due to the slow and widely varying pulse shapes. To investigate the influence of detector geometry and the effectiveness of timing techniques, wide and narrow dynamic range time resolution measurements were made for three shapes of high efficiency detectors using four timing methods. The resolution obtained with true coaxial detectors was about a factor of two better than the others. Timing methods which attempt to compensate for pulse shape variations were substantially better than leading edge discrimination, especially for wide dynamic range.