Properties of levels of ${}_{}{}^{28}{}_{}{}^{}\mathrm{Al}$ with $E_{\mathrm{ex}}<2.7\mathrm{}$ MeV have been studied by means of the reactions ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}(d,p\gamma ){}_{}{}^{28}{}_{}{}^{}\mathrm{Al}$, ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}({}_{}{}^3{}_{}{}^{}\mathrm{He},p\gamma ){}_{}{}^{28}{}_{}{}^{}\mathrm{Al}$, and ${}_{}{}^{30}{}_{}{}^{}\mathrm{Si}(d,\alpha \gamma ){}_{}{}^{28}{}_{}{}^{}\mathrm{Al}$. The decay schemes of the first 12 excited states were determined. The known level at 1.62 MeV was found to consist of a doublet with a separation of 2.5 ± 1 keV. Particle-$\gamma$ angular-correlation measurements using an annular silicon diode and a Ge(Li) detector led to spin-parity assignments of $3^{+}$, ($2^{+}$) for the third level, and $1^{+}$ for the fourth level. For a number of $\gamma$-ray transitions the $\frac{E2\mathrm{}}{M1\mathrm{}}$ mixing ratio was determined. A new method was applied to the measurement and analysis of the angular correlations. The results obtained are compared with the predictions of a simple shell model.

The low-lying levels in ${}_{}{}^{46}{}_{}{}^{}\mathrm{Sc}$ have been observed with (${}_{}{}^3{}_{}{}^{}\mathrm{He},t$) reactions on ${}_{}{}^{46}{}_{}{}^{}\mathrm{Ca}$ by use of the 22.5-MeV ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ beam of the Argonne tandem Van de Graaff and the split-pole spectrograph. Of the 26 levels observed below 3-MeV excitation, 18 were tentatively fitted with distorted-wave curves. In a number of cases the choices of possible spins for the levels could be reduced by comparing the present results with previous experiments.

The linear polarization has been measured for the 2.21-, 2.73-, 2.98-, and 3.00-MeV transitions in ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$. The mixing ratios $\delta \left(\frac{E2\mathrm{}}{M1\mathrm{}}\right)$ for these transitions were determined to be $\delta \mathrm{}\left(2.21\right)=-0.57\mathrm{}\pm 0.08$, $\delta \mathrm{}\left(2.73\right)=0.22\mathrm{}\pm 0.09$, and $\delta \mathrm{}\left(2.98\right)=0.05\mathrm{}\pm 0.03$. The 3.00-MeV transition was found to be consistent with a pure $E2\mathrm{}$ transition. The results are compared with the predictions of the rotational-vibrational model of Röpke.

The ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}({}_{}{}^3{}_{}{}^{}\mathrm{He},t){}_{}{}^{40}{}_{}{}^{}\mathrm{Sc}$ reaction has been studied using solid-state telescopes and a magnetic spectrograph. Data are compared with the results of microscopic calculations using either pure shell-model or configuration-mixed wave functions. The cross-shell transition strengths to the observed negative-parity states in ${}_{}{}^{40}{}_{}{}^{}\mathrm{Sc}$ have the same order of magnitude as those measured previously for the (${}_{}{}^3{}_{}{}^{}\mathrm{He},t$) reaction on the $N=28\mathrm{}$ nuclei. Empirical values have been obtained for the effective projectile-nucleon interaction. Using these values, some of the [${\left(f_{\frac{7}{2}}\right)}_p{\left(d_{\frac{3}{2}}^{}{}_{}{}^{-1\mathrm{}}\right)}_n$], [${\left(p_{\frac{3}{2}}\right)}_p{\left(d_{\frac{3}{2}}^{}{}_{}{}^{-1\mathrm{}}\right)}_n$], and [${\left(f_{\frac{7}{2}}\right)}_p{\left(s_{\frac{1}{2}}^{}{}_{}{}^{-1\mathrm{}}\right)}_n$] states are identified and the effect of configuration mixing is discussed.

The ($\alpha ,{\alpha }^{\prime }$) reaction, at $E_{\alpha }=31\mathrm{}$ MeV, on ${\mathrm{Zn}}^{68}$ and ${\mathrm{Zn}}^{70}$ was studied with an over-all energy resolution of 70-120 keV. Angular distributions are presented. New $3^{-}$, $4^{+}$, and $5^{-}$ assignments are made on the basis of distorted-wave Born-approximation (DWBA) calculations. Good angular distributions were obtained for double-excitation $2^{+}$ states at 1.88 MeV in ${\mathrm{Zn}}^{68}$ and at 1.78 MeV in ${\mathrm{Zn}}^{70}$. Fractionation of the octupole strength has been observed. Systematics of excitation energies and strengths are discussed for ${\mathrm{Zn}}^{64}$, ${\mathrm{Zn}}^{66}$, ${\mathrm{Zn}}^{68}$, and ${\mathrm{Zn}}^{70}$.

Conventional random-phase-approximation (RPA) and corrected RPA (MRPA) calculations are carried out for ${}_{}{}^{56}{}_{}{}^{}\mathrm{Ni}$ and ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ nuclei, using the Tabakin potential without and with secondorder Born corrections. The obtained ground-state wave functions are analyzed. The probability for the doubly-closed-shell (zero-particle, zero-hole) configurations is found to be small for ${}_{}{}^{56}{}_{}{}^{}\mathrm{Ni}$ [18% (RPA), 38% (MRPA)]. Similar numbers for the ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ nucleus are, 35% RPA, 56% (80% for protons and 69% for neutrons) MRPA. In the case of ${}_{}{}^{56}{}_{}{}^{}\mathrm{Ni}$, the $T=0\mathrm{}$ part contributes ≃95% to the shell breaking. The occupation numbers for single-particle and single-hole states are small except for the $1f_{\frac{7}{2}}$ hole and $1f_{\frac{5}{2}}$ particle states in ${}_{}{}^{56}{}_{}{}^{}\mathrm{Ni}$, and for the $1d_{\frac{3}{2}}$ proton-hole state in ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$. It is found that the conventional RPA using antisymmetrized matrix elements overestimates the calculated quantities of the ground state, roughly by a factor of 2. The effect of truncating the configuration space is also studied quantitatively. The results are compared with earlier investigations.

The cross sections for the production of ${}_{}{}^{48}{}_{}{}^{}\mathrm{V}$, ${}_{}{}^{48}{}_{}{}^{}\mathrm{Sc}$, ${}_{}{}^{47}{}_{}{}^{}\mathrm{Sc}$, ${}_{}{}^{47}{}_{}{}^{}\mathrm{Ca}$, ${}_{}{}^{46}{}_{}{}^{}\mathrm{Sc}$, ${}_{}{}^{44m}{}_{}{}^{}\mathrm{Sc}$, ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ti}$, ${}_{}{}^{43}{}_{}{}^{}\mathrm{K}$, ${}_{}{}^{42}{}_{}{}^{}\mathrm{K}$, ${}_{}{}^{28}{}_{}{}^{}\mathrm{Mg}$, ${}_{}{}^{24}{}_{}{}^{}\mathrm{Na}$, ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$, and ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ from 15- to 584-MeV proton spallation of titanium are reported. The experimental production rates of the various isotopes and their ratios to ${}_{}{}^{47}{}_{}{}^{}\mathrm{Sc}$ are compared with theoretical spallation-yield calculations. Application of the measured excitation functions to the analysis of lunar materials and meterorites is discussed.

The cross sections for the production of ${}_{}{}^{57}{}_{}{}^{}\mathrm{Co}$, ${}_{}{}^{56}{}_{}{}^{}\mathrm{Co}$, ${}_{}{}^{55}{}_{}{}^{}\mathrm{Co}$, ${}_{}{}^{54}{}_{}{}^{}\mathrm{Mn}$, ${}_{}{}^{52}{}_{}{}^{}\mathrm{Mn}$, ${}_{}{}^{51}{}_{}{}^{}\mathrm{Cr}$, ${}_{}{}^{48}{}_{}{}^{}\mathrm{Cr}$, ${}_{}{}^{48}{}_{}{}^{}\mathrm{V}$, ${}_{}{}^{48}{}_{}{}^{}\mathrm{Sc}$, ${}_{}{}^{47}{}_{}{}^{}\mathrm{Sc}$, ${}_{}{}^{46}{}_{}{}^{}\mathrm{Sc}$, ${}_{}{}^{44m}{}_{}{}^{}\mathrm{Sc}$, ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ti}$, ${}_{}{}^{43}{}_{}{}^{}\mathrm{K}$, ${}_{}{}^{42}{}_{}{}^{}\mathrm{K}$, ${}_{}{}^{24}{}_{}{}^{}\mathrm{Na}$, and ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$, from 14.1 to 585-MeV proton spallation of iron are reported. The experimental production rates of the various radioisotopes and their ratios to ${}_{}{}^{54}{}_{}{}^{}\mathrm{Mn}$ are compared to theoretical spallation-yield calculations. These data and previously published data are combined to develop the excitation functions for these isotopes from proton spallation of natural iron. Applications of these excitation functions to beam monitoring and to the studies of meteorites and lunar surface material are discussed.

Results are presented of calculations made in the full space of $\mathrm{sd}$-shell-model wave functions for positive-parity states in the nuclei with $A=34\mathrm{}-38$. We employed in this work several different effective Hamiltonians, some of which had two-body parts obtained by reaction-matrix techniques from the Hamada-Johnston scattering potential. The observables calculated were energy-level spectra, single-nucleon spectroscopic factors, and $E2\mathrm{}$ and $M1\mathrm{}$ moments and transition strengths. These calculations yield fair-to-good agreement with many of the observed nuclear-structure data in this mass region.

The photoneutron cross sections for ${}_{}{}^{53}{}_{}{}^{}\mathrm{Cr}$, ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$, and ${}_{}{}^{61}{}_{}{}^{}\mathrm{Ni}$ have been measured near threshold with high resolution. Nuclear states of interest were excited by photon absorption from a bremsstrahlung beam whose end-point energy was sufficient only for neutron decay to the ground state of the daughter. Spins of resonances were assigned on the basis of angular distributions determined from the spectra for neutron emission at angles of 90 and 135°; the ground-state radiation widths ${\Gamma }_{\gamma 0}$ for most resonances were determined from the observed yields. Parity assignments were based on a comparison of data with total neutron cross sections of the daughter nuclei. The central feature of the results is an intense $p$-wave component whose integrated strength for all targets is greater than that of the $s$-wave component. In addition, an anomalous concentration of $M1\mathrm{}$ strength is observed in an intense doublet with $J^{\pi }={\frac{3}{2}}^{-}$ at $E_n=230\mathrm{}$ keV in the cross section for ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$. The reduced widths for $E1\mathrm{}$ and $M1\mathrm{}$ radiation are consistent with the values ${\overline{k}}_{E1\mathrm{}}=0.0012\mathrm{}$ and ${\overline{k}}_{M1\mathrm{}}=0.019\mathrm{}$, respectively.

No evidence is found in the reactions ${}_{}{}^{53}{}_{}{}^{}\mathrm{Cr}(\gamma ,n)$ and ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}(\gamma ,n)$ near threshold for doorway states which have been proposed in the literature. The data were also tested for a correlation between the reduced neutron width for $s$-wave resonances in each target and the corresponding ground-state radiation widths. In no case is there evidence for a significant correlation. Therefore the strong correlation reported between the reduced neutron widths and total radiation widths for $s$-wave resonances in even-even target nuclei in this mass region should not be attributed to the ground-state transition.

Angular distributions have been measured of $\gamma$ radiations emitted in the decay of ${}_{}{}^{122}{}_{}{}^{}\mathrm{Sb}$ nuclei oriented at low temperatures in an iron lattice. Angular momentum admixtures in the (first forbidden) $\beta$ radiation fields have been deduced; results indicate that the component of the radiation field carrying away two units of angular momentum contributes to the electron-capture decay to ${}_{}{}^{122}{}_{}{}^{}\mathrm{Sn}$ with at least twice the magnitude as to the ${\beta }^{-}$ decay to ${}_{}{}^{122}{}_{}{}^{}\mathrm{Te}$. These results are interpreted in terms of particle-hole correlations in the nuclear shell model. In addition, the $\frac{E2\mathrm{}}{M1\mathrm{}}$ mixing ratio of the 691-keV $\gamma$ transition in ${}_{}{}^{122}{}_{}{}^{}\mathrm{Te}$ is deduced to be -2.90 ± 0.25.

The ${}_{}{}^{174}{}_{}{}^{}\mathrm{Ta}$ activity was produced via the ${}_{}{}^{175}{}_{}{}^{}\mathrm{Lu}(\alpha ,5n){}_{}{}^{174}{}_{}{}^{}\mathrm{Ta}$ reaction with 66-MeV $\alpha$ particles from the Crocker Nuclear Laboratory 76-in. isochronous cyclotron. After removal of the ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$, the half-lives were deduced by direct measurements. The half-lives of approximately 200 transitions, ranging in energy from 60 to 3000 keV, were identified using Ge(Li) detectors. Over 95% of these lines were assigned to ${}_{}{}^{175}{}_{}{}^{}\mathrm{Hf}$, ${}_{}{}^{174}{}_{}{}^{}\mathrm{Hf}$, or ${}_{}{}^{173}{}_{}{}^{}\mathrm{Lu}$. The half-life of ${}_{}{}^{174}{}_{}{}^{}\mathrm{Ta}$ was measured to be 71.5 ± 6.5 min. Ge(Li)-Nal coincidence work has been done. The conversion-electron spectrum was first measured using a 3-mm Si(Li) detector with a cooled field-effect transistor and then using the same type of detector plus a magnet.

The energies and $\gamma$ intensities of the 100 transitions attributed to the decay of ${}_{}{}^{174}{}_{}{}^{}\mathrm{Ta}$ were measured. 32 conversion coefficients were determined. 16 levels with spins and parities are proposed on the basis of $\gamma$ intensities, coincidence information, and conversion coefficients. 16 more levels are proposed on the basis of energy sums. Spins and parities for four of these levels are suggested. 60 transitions are placed in the decay scheme. A very strong $\beta$ feed to the 4+ level of the ground-state rotational band was observed. $M1\mathrm{}$ enhancement in the $\beta$ vibrational bands and $K$-forbidden $\gamma$ transitions are discussed.

A large-aperture low-resolution magnetic spectrometer was constructed to search for the double $\beta$ decay of ${\mathrm{Nd}}^{150}$. The spectrometer was operated for approximately 750 h in the low-background environment of a salt mine, 585 m below ground level. The observed count rate is consistent with a lower limit for the half-life of 5 × ${10}^{18}$ yr for the decay of ${\mathrm{Nd}}^{150}\to {\mathrm{Sm}}^{150}+2\mathrm{}{e}^{-}+2\mathrm{}{\tilde{\nu }}_e$ and 7 × ${10}^{18}$ yr for the mode ${\mathrm{Nd}}^{150}\to {\mathrm{Sm}}^{150}+2\mathrm{}{e}^{-}$.

Radioactive sources of ${}_{}{}^{154}{}_{}{}^{}\mathrm{Tb}$ made by the ${}_{}{}^{153}{}_{}{}^{}\mathrm{Eu}(\alpha ,3n)$ and ${}_{}{}^{155}{}_{}{}^{}\mathrm{Gd}\mathrm{}(p,2n)\mathrm{}$ reactions have been studied with Ge(Li) and Si(Li) detectors. A new isomer ($T_{\frac{1}{2}}=22.5\mathrm{}\pm 1.5$ h; spin and parity probably $7^{-}$) has been found in ${}_{}{}^{154}{}_{}{}^{}\mathrm{Tb}$. This state decays primarily to an $I^{\pi }K=7^{-}7$ isomeric state at 2137.8 keV in ${}_{}{}^{154}{}_{}{}^{}\mathrm{Gd}$. Quasiparticle configurations involving the ${\frac{11}{2}}^{-}\mathrm{}\left[505\right]\mathrm{}$ neutron orbital are proposed for both of these isomeric states, and retardation factors are determined for transitions from the 2137.8-keV state.

Data have been obtained from radiochemical studies which indicate that ternary fission has been induced in ${\mathrm{Bi}}^{209}$ and ${\mathrm{Pu}}^{239}$ with intermediate-energy (≤60-MeV) helium ions. ${\mathrm{Mg}}^{28}$, a nuclide prominent in the ternary fission of ${\mathrm{U}}^{238}$, was used as a semiquantitative monitor for the ternary process. The low limit set for ${\mathrm{Ca}}^{47}$ in these fissioning systems also substantiates the ternary-fission-product nature of ${\mathrm{Mg}}^{28}$. No evidence was found for the formation of ${\mathrm{Mg}}^{28}$ in ${\mathrm{Au}}^{197}$ irradiated with helium ions until excitation energies ≤64 MeV were used, but at these energies the yields of ${\mathrm{Ca}}^{47}$ were greater than the yields of ${\mathrm{Mg}}^{28}$. These observations are consistent with the postulated change in the nature of the saddle-point shapes of lower-$Z$ nuclides having a fissionability parameter, $x$, ≤0.67.

The cross sections for 34 nuclides covering the mass range 24 to 199 formed from the ${\mathrm{He}}^4$ ion-induced fission of ${\mathrm{Th}}^{232}$ at 20-41 MeV have been determined radiochemically. The resulting mass-yield curve clearly indicates contributions from at least three different types of fission: the symmetric binary, asymmetric binary, and asymmetric ternary modes. The identification of very light fragments and the low limits set on ${\mathrm{Au}}^{199}$ confirm the existence of ternary fission seen previously in this laboratory in plutonium compound nuclei. Certain similarities and differences in this fissioning system to other heavier elements are discussed.

The presence of isospin coupling in the incident channel has been studied via proton-induced reactions on ${}_{}{}^{95,98,100}{}_{}{}^{}\mathrm{Mo}$ and ${}_{}{}^{92,94}{}_{}{}^{}\mathrm{Zr}$. Anomalous behavior in the excitation functions at backward angles was observed in deuteron and proton outgoing channels. In the deuteron channels these anomalies, located near the ($p,n$) threshold to the ground-state analog, were, for almost all cases, similarly characterized by a double-dipped shape. Their strength is generally much weaker than the single minima observed in ($d,p$) reactions near mass 90 and can be categorized by the proton decay energy from the analog state formed in the charge-exchange process. The proton elastic excitation functions showed no structure near the ($p,n$) thresholds although the ($p,p^{\prime }$) curves did exhibit fluctuations.

The (${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$) $\alpha$-transfer reaction has been studied on several Ca and Ti target isotopes using the 40- and 48-MeV ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ beams of the Saclay FN tandem Van de Graaff. This work is the natural extension of the previous one performed on various Fe and Ni target isotopes. As previously observed for Ni and Zn residual nuclei, a small number of levels are strongly and selectively excited at low energy. This $\alpha$-transfer reaction appears, then, as a new spectroscopic tool to study four-nucleon correlations. In close connection with the previous data on Fe and Ni targets, the present article points out the importance in residual nuclei of the quartet structure: namely two protons and two neutrons mutually strongly bound and weakly coupled to the target core. A strong blocking effect on the quartet is observed as soon as a neutron-pair excess is present in the target ground state. This neutron blocking effect has been already observed in the Fe and Ni target case. The existence in the $1f-2p$ shell of quartetting phenomena, i.e., the presence of four highly correlated nucleons giving rise to a quasirotational band, establishes the interplay between spherical and deformed states already known to exist in lighter nuclei.

The magnetic dipole moments of the first $2^{+}$ states in ${\mathrm{Os}}^{192}$ and ${\mathrm{Pt}}^{192}$ have been measured, using integral perturbed-angular-correlation (PAC) methods, to be $\mu =0.797\mathrm{}\pm 0.036{\mu }_N$ and $\mu =0.90\mathrm{}\pm 0.11{\mu }_N$, respectively. Integral PAC measurements were performed using both Fe(Ir) and Ni(Ir) alloys, and it has been established that the Fe(Ir) alloy is not a suitable environment for a PAC experiment. Significantly, the results agree with the $2\left(\frac{Z}{A}\right)$ hydrodynamical values, but differ appreciably from the predictions of the Kumar and Baranger pairing-plus-quadru-pole model. The room-temperature internal magnetic fields of ${\mathrm{Os}}^{187}$ in Fe and Ni lattices have been measured by steady-state NMR methods to be $H_{\mathrm{int}}\left(296\mathrm{}°\mathrm{K}\right)=-1093.43\mathrm{}\pm 0.65$ kOe and $H_{\mathrm{int}}\left(295\mathrm{}°\mathrm{K}\right)=-282.3\mathrm{}\pm 1.0$ kOe, respectively.

Fission-fragment mass and kinetic energy distributions have been obtained for the spontaneous fission of ${\mathrm{Pu}}^{240}$ and compared with those for the thermal-neutron-induced fission of ${\mathrm{Pu}}^{239}$ reported previously. Surface-barrier detectors were used for the simultaneous measurements of energies of both the fission fragments. Absolute fragment energies were calculated by using mass-dependent pulse-height energy relations. The measured average total kinetic energies were found to be 177.3 ± 1.5 MeV and 173.0 ± 1.5 MeV for the spontaneous and the induced fission, respectively, and the average pre-neutron total kinetic energies were 178.9 ± 1.5 MeV and 175.2 ± 1.5 MeV, respectively. The measured mass distribution for the spontaneous fission appears to be significantly different in shape from that for the induced fission.