It is shown that the size of external isospin mixing depends upon the correlations between mirror channels. In the limit of vanishing charge, these correlations yield zero external mixing. For the actual strength of the Coulomb field, our analysis corroborates the estimates of external mixing given earlier. We present formulas for cross-section correlations between mirror channels.

NUCLEAR REACTIONS Isospin mixing in compound nucleus reactions.

The effects of electromagnetically induced spin-dependent potentials on the analyzing power for low-energy proton-proton scattering are calculated using the Coulomb-distorted-wave Born approximation. The amplitudes which arise from these potentials are nearly in phase with the usual Coulomb amplitude and as a result the potentials have virtually no effect on the analyzing power.

NUCLEAR REACTIONS polarized $p-p$ scattering, electromagnetic effects.

The angular distribution for the ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}(\gamma , n_0){}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ reaction was observed throughout the excitation energy region 4.3-7 MeV and at angles of 90° and 135°. The ground-state radiation widths for resonances in this energy region were extracted from the data. The value of the radiation width for the $d_{\frac{5}{2}}\to d_{\frac{3}{2}}$ spin-flip transition at 5.08 MeV was found to be approximately $\frac{1}{3}$ of the value expected for a pure single-particle transition. The implications that this result has for the nuclear structure of ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ is discussed. The effects of potential radiative capture were observed directly in a photoneutron reaction for the first time. At the location of the 5.38-MeV, $\frac{3}{2^{-}}$ resonance in ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$, an anomalous symmetric dip was observed in the cross section at both reaction angles. The data were interpreted in terms of a general $R$-matrix reaction theory which includes the effects of internal, channel, and potential radiative capture in a self-consistent manner. The neutron channel was defined by incorporating an $R$-matrix analysis of the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}(n, n){}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ reaction into the present interpretation. The anomalous minimum at 5.38 MeV was found to be due to a unique feature of channel capture. The $R$-matrix prediction for the total cross section was extrapolated into the keV region and the significance that this cross section has for stellar nucleosynthesis is discussed.

NUCLEAR REACTIONS ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}(\gamma , n_0){}_{}{}^{16}{}_{}{}^{}\mathrm{O}$; observed angular distribution; $E_{\gamma }=4.3-7\mathrm{}$ MeV; $\theta =90\mathrm{}°, 135°$; $R$-matrix analysis; measured ${\Gamma }_{\gamma 0}$ for $E1\mathrm{}$ and $M1\mathrm{}$ resonances.

We have measured the $\gamma$-ray branching ratios of the lowest $T=\frac{3}{2}$ states in the isospin mirror nuclei ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$ and ${}_{}{}^9{}_{}{}^{}\mathrm{B}$. The ratio of reduced $M1\mathrm{}$ transition strengths $\frac{B_{{\gamma }_2}\mathrm{}\left(M1\mathrm{}\right)\mathrm{}}{B_{{\gamma }_0}\mathrm{}\left(M1\mathrm{}\right)\mathrm{}}=1.97\mathrm{}\pm 0.12$ in ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$ and 1.76±0.21 in ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$ and hence shows no charge asymmetry, in agreement with the usual selection rules for $\Delta T=1\mathrm{}$ electromagnetic transitions. A value of (1.9±2.1)% is derived for the relative size of any isotensor amplitudes for the $M1\mathrm{}$ transitions. For the total widths of the $T=\frac{3}{2}$ levels we find $\Gamma \left({}_{}{}^9{}_{}{}^{}\mathrm{Be}\right)=381\mathrm{}\pm 33$ eV, $\Gamma \left({}_{}{}^9{}_{}{}^{}\mathrm{B}\right)=395\mathrm{}\pm 42$ eV, and $\frac{\Gamma \left({}_{}{}^9{}_{}{}^{}\mathrm{B}\right)}{\Gamma \left({}_{}{}^9{}_{}{}^{}\mathrm{Be}\right)}=1.04\mathrm{}\pm 0.10$, assuming $B_{{\gamma }_0}(M1, {}_{}{}^9{}_{}{}^{}\mathrm{B})=B_{{\gamma }_0}(M1, {}_{}{}^9{}_{}{}^{}\mathrm{Be})$ and ${\Gamma }_{{\gamma }_0}=6.9\mathrm{}\pm 0.5$ eV in ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$. The $\gamma$-ray transition strengths are compared with theoretical calculations and with the analogous $\beta$ decay of ${}_{}{}^9{}_{}{}^{}\mathrm{Li}$.

NUCLEAR REACTIONS ${}_{}{}^7{}_{}{}^{}\mathrm{Li}({}_{}{}^3{}_{}{}^{}\mathrm{He}, p\gamma )$, ${}_{}{}^7{}_{}{}^{}\mathrm{Li}(\mathrm{He}, n\gamma )$, particle-$\gamma$ coincidence; measured $\frac{{\Gamma }_{{\gamma }_i}}{\Gamma }$ and deduced ${\Gamma }_{{\gamma }_i}$ and $\Gamma$ for ${}_{}{}^9{}_{}{}^{}\mathrm{Be}(T=\frac{3}{2})$ and ${}_{}{}^9{}_{}{}^{}\mathrm{Be}(T=\frac{3}{2})$; symmetry of mirror transitions.

Measurements have been made of the $p$+${}_{}{}^4{}_{}{}^{}\mathrm{He}$ elastic scattering angular distributions at $T=21.85, 23.90, 25.75, 28.10, 30.35, 32.15, 34.25, 36.90, 39.75, 42.45, 44.05, 44.95, \mathrm{and} 47.65$ MeV in the angular range $10°\lesssim {\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}\lesssim 170°$. The data obtained have in general relative errors smaller than 2%, while the absolute scale of the measurements has an uncertainty of less than 2.5%. These data together with differential cross sections and analyzing power angular distributions selected from the literature, as well as total reaction cross section information have been subjected to a phase shift analysis. Up to 45 MeV a single, continuous solution could be determined using phase shifts up through $G$-waves. As in an earlier phase shift analysis the phase shifts exhibit a smooth variation with energy except for the well-known resonance region around 23.4 MeV. Above 45 MeV some improvement was obtained with the inclusion of a small $H$-wave contribution. New total reaction cross section data were employed as a constraint on the imaginary parts of the phase shifts. The new analysis corroborates an early finding that the inelasticity is mainly associated with the even partial waves.

NUCLEAR REACTIONS Measured $\frac{d\sigma }{d\Omega }$ for ${}_{}{}^4{}_{}{}^{}\mathrm{He}(p, p){}_{}{}^4{}_{}{}^{}\mathrm{He}$ at $T=21.85, 23.90, 25.75, 28.10, 30.35, 32.15, 34.25, 36.90, 39.75, 42.45, 44.05, 44.95, \mathrm{and} 47.65$ MeV for $10°\lesssim {\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}\lesssim 170°$; phase shift analysis using $\frac{d\sigma }{d\Omega }$ and other selected $\frac{d\sigma }{d\Omega }$, $A$, and ${\sigma }_R$ from the literature, $20 \mathrm{MeV}<T<~55 \mathrm{MeV}$.

Angular distributions of the ${}_{}{}^2{}_{}{}^{}\mathrm{H}(d, d){}_{}{}^2{}_{}{}^{}\mathrm{H}$, ${}_{}{}^2{}_{}{}^{}\mathrm{H}(d, p){}_{}{}^3{}_{}{}^{}\mathrm{H}$, and ${}_{}{}^2{}_{}{}^{}\mathrm{H}(d, n){}_{}{}^3{}_{}{}^{}\mathrm{He}$ reactions at six incident energies in the 50-85 MeV range have been measured. The ${}_{}{}^2{}_{}{}^{}\mathrm{H}(d, p){}_{}{}^3{}_{}{}^{}\mathrm{H}$ reaction data have been analyzed in terms of the plane-wave Born-approximation theory. A smooth cutoff in the partial wave expansion of the reaction matrix has been introduced to allow the suppression of the low angular momentum components. The calculated angular distributions obtained with a constant cutoff angular momentum $l_{\mathrm{co}}=3\mathrm{}$ show reasonably good agreement with the experimental data in the whole 50-85 MeV energy range. This is consistent with the peripheral character of the reaction.

NUCLEAR REACTIONS ${}_{}{}^2{}_{}{}^{}\mathrm{H}(d, d)$, ${}_{}{}^2{}_{}{}^{}\mathrm{H}(d, p)$, ${}_{}{}^2{}_{}{}^{}\mathrm{H}(d, n)$, $E=50-85\mathrm{}$ MeV; measured $\frac{d\sigma }{d\Omega }$; analysis in terms of PWBA with a smooth $l$ cutoff; deduced cutoff angular momenta.

Nineteen resonances corresponding to excitations between 6.9 and 8.3 MeV have been observed in ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$+$p$ reactions between $E_p=1400\mathrm{} \mathrm{and} 2800$ keV. From the Breit-Wigner analysis of the excitation function shapes for the various outgoing channels, resonance strengths were obtained and the partial widths deduced. Branching ratios of the $\gamma$ rays were determined and in one case the $\gamma$-ray angular distribution could be measured and used for $J^{\pi }$ assignment. A reaction $Q$ value of 5604±2.5 keV was found.

NUCLEAR REACTIONS ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}(p, {\alpha }_0)$, ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}(p, p_1\gamma )$, and ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}(p, \gamma )$, $E_p=1.4-2.8\mathrm{}$ MeV; measured $\sigma (E_p, \theta )$, $Q$. ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ deduced levels, $J^{\pi }$, $\Gamma$, $T$. Enriched target.

Methods for embedding phenomenological distorted-wave techniques for rearrangement and inelastic scattering within well-defined theories of multiparticle scattering are developed. The essential point of contact between the two approaches is in the definition and choice of distorting potential. It is shown that the concept of a channel coupling scheme allows a comparative freedom of choice for these potentials; if they are connected operators, such as optical potentials, then it is possible to obtain connected-kernel equations for the distorted transition operators. The latter are introduced in the course of exploiting the two-potential formula for the full transition operator and have the property that their matrix elements with respect to distorted waves are the physical scattering amplitudes. It is found that the distorted counterparts of the Kouri, Levin, and Tobocman and the Bencze-Redish integral equations maintain their connected-kernel and minimally coupled properties. These equations can be used to derive other integral equations with the same properties for the distorted-wave operators which consist of the product of the distorted transition operators and the wave operators corresponding to distorted waves. These simplifications are not realized for arbitrary channel coupling schemes. In order to deal with the general situation an alternative approach employing a subtraction technique which involves projections on the bound two-cluster channel states is introduced. When the distorting potentials are essentially the optical potentials in the entrance and exit channels a set of multichannel two-particle Lippmann-Schwinger integral equations for the two-cluster distorted-wave transition operators are obtained. The input into these two-particle integral equations involves the solution of a modified $N$-particle equation. Approximations to the latter are discussed in the particular cases of the Kouri, Levin, and Tobocman and Bencze-Redish channel coupling schemes. The inhomogeneous terms of all of the integral equations investigated for the distorted transition operator are of particular interest in connection with the distorted-wave Born approximation and modifications to it.

NUCLEAR REACTIONS Distorted-wave techniques, $N$-particle scattering, integral equations, channel coupling, distorted-wave Born-approximation, scattering theory.

The states of ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ below 11 MeV have been studied using the ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}({}_{}{}^3{}_{}{}^{}\mathrm{He}, d)$ reaction at a bombarding energy of 15 MeV. Angular distributions of the reaction products have been compared with distorted-wave Born-approximation predictions. The resulting spectroscopic factors are compared with those calculated using the Nilsson model and with experimental spectroscopic factors of previous ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}({}_{}{}^3{}_{}{}^{}\mathrm{He}, d)$ and ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}(d, n)$ studies. Several new rotational bands based on collective-model configurations are suggested. The experimentally measured spectroscopic factors for states based on the ${\left(\frac{3}{2^{+}}\mathrm{}\right[211\left]\right)}^2$, the $\frac{3}{2^{+}}\mathrm{}\left[211\right]\mathrm{}$, $\frac{1}{2^{+}}\mathrm{}\left[211\right]\mathrm{}$, and the $\frac{3}{2^{+}}\mathrm{}\left[211\right]\mathrm{}$, $\frac{1}{2^{-}}\mathrm{}\left[330\right]\mathrm{}$ Nilsson configurations are in general agreement with the predictions of the simple Nilsson model assuming large deformations. It is necessary to assume that the $T=1\mathrm{}$ states are less deformed than the $T=0\mathrm{}$ states in order to explain the properties of the low-lying $T=1\mathrm{}$ states in terms of the collective model.

NUCLEAR REACTIONS ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}({}_{}{}^3{}_{}{}^{}\mathrm{He}, d)$, $E=15.0\mathrm{}$ MeV; measured $\sigma (E_d, \theta )$. ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ deduced levels, $J$, $\pi$, $S$. DWBA analysis. Comparison with Nilsson model.

Using time-of-flight techniques in conjunction with a 29.6-m flight path at 0°, the population of 1+ levels in the ${}_{}{}^{58}{}_{}{}^{}\mathrm{Fe}(p, n)$ reaction has been investigated at 20.2-MeV bombarding energy. The measured ($p, n$) 1+ strength distribution is different from that seen in ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}(t, {}_{}{}^3{}_{}{}^{}\mathrm{He})$ ${}_{}{}^{58}{}_{}{}^{}\mathrm{Co}$ but similar to that seen in ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}(e, e^{\prime })$ for populating the $T^{>}$ 1+ analog states. Shell model calculations give a fair description of the ($p, n$) 1+ strengths. The ($t$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$) and ($e, e^{\prime }$) 1+ calculated strengths (identical using our model) do not agree with either the ($t$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$) or ($e, e^{\prime }$) measured strengths. The indications are that 4p-2h structure for both the ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ ground state and the 1+, $T=2\mathrm{}$ states is necessary to explain the measured ($e, e^{\prime }$) strengths. This is supported by our shell model calculations, which show that the low-lying parent 1+ levels in ${}_{}{}^{58}{}_{}{}^{}\mathrm{Co}$ are predominantly 4p-2h in structure with the four particles in the $p_{\frac{3}{2}}-p_{\frac{1}{2}}$ orbits, contrary to the simplest assumption of 3p-1h structure with at least one particle in the $f_{\frac{5}{2}}$ orbit. The fact that ($e, e^{\prime }$) and ($t$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$) 1+ strengths differ experimentally may be due to two-step processes contributing to the ($t$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$) reaction.

NUCLEAR REACTIONS ${}_{}{}^{58}{}_{}{}^{}\mathrm{Fe}(p, n){}_{}{}^{58}{}_{}{}^{}\mathrm{Co}_{}^{*}{}_{}{}^{}\left(1^{*}\right)$, $E=16, 19.1, 20.2$ MeV; Comparison with ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}(t, {}_{}{}^3{}_{}{}^{}\mathrm{He}){}_{}{}^{58}{}_{}{}^{}\mathrm{Co}_{}^{*}{}_{}{}^{}\left(1^{*}\right)$ and ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}(e, e^{\prime }){}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}_{}^{*}{}_{}{}^{}$ (1+, $T=2\mathrm{}$); Shell-model calculations of $M1\mathrm{}$ strength distributions for all three reactions.

The $g$ factor of the 575-keV $\frac{11}{2^{-}}$ isomer in ${}_{}{}^{129}{}_{}{}^{}\mathrm{Cs}$ has been measured by the time differential perturbed angular distribution technique using the ${}_{}{}^{127}{}_{}{}^{}\mathrm{I}(\alpha , 2n){}_{}{}^{129}{}_{}{}^{}\mathrm{Cs}$ reaction with a thick CsI target to maintain alignment. A value of $g=+1.191\mathrm{}\pm 0.018$ was obtained, which is consistent after $M1\mathrm{}$ core-polarization corrections with a predominantly $1h_{\frac{11}{2}}$ quasiproton structure for this state. The experiment also yielded a remeasurement of the mean lifetime of the isomer as $\tau =1059\mathrm{}\pm 33$ nsec.

NUCLEAR REACTIONS ${}_{}{}^{127}{}_{}{}^{}\mathrm{I}(\alpha , 2n){}_{}{}^{129}{}_{}{}^{}\mathrm{Cs}\left({\frac{11}{2}}^{-}\right)$, $E_{\alpha }=22\mathrm{}$ MeV, pulsed beam, CsI target, measured spin rotation in $B=9.2\mathrm{}$ kG, deduced $g$.

The ${}_{}{}^{52}{}_{}{}^{}\mathrm{Cr}(p, \alpha ){}_{}{}^{49}{}_{}{}^{}\mathrm{V}$ reaction has been studied at a bombarding energy of 35 MeV. The qualitative features of the spectra are discussed. These include the population of proton hole states, analog states, and high spin states. The spectra are compared with other pick-up reaction data and the comparison is shown to be a useful tool for identifying positive parity states in this region. Some states which are observed in ${}_{}{}^{51}{}_{}{}^{}\mathrm{V}(p, t){}_{}{}^{49}{}_{}{}^{}\mathrm{V}$ data are not observed in the ($p, \alpha$) spectra. Distorted-wave calculations using mass three cluster form factors are described and shown to reproduce the experimental angular distributiions of the previously known levels. Similar calculations using microscopic form factors also reproduce the shapes of the angular distributions reasonably well. Relative spectroscopic factors for the proton hole states deduced from the microscopic calculations are shown to be in good agreement with zero order shell model predictions. The general trends of the experimental cross sections for the negative parity microscopic states are shown to be reproduced by microscopic calculations assuming $0{f_{\frac{7}{2}}}^3$ pickup.

NUCLEAR REACTIONS ${}_{}{}^{52}{}_{}{}^{}\mathrm{Cr}(p, \alpha )$, $E_p=35\mathrm{}$ MeV; measured $\sigma \left(E_x\theta \right)$, deduced energy levels; studied reaction mechanism.

Total neutron capture cross section measurements have been carriedout for ${}_{}{}^{55}{}_{}{}^{}\mathrm{Mn}(I=\frac{5}{2})$ over the energy interval of 2.5-600 keV. Using time-of-flight techniques and a nonhydrogenous liquid scintillator detector system, resonance energies and capture area were determined for some 143 resonances to 112 keV neutron energy. Values of radiation widths (${\Gamma }_{\gamma }$) were evaluated for broad $l=0\mathrm{}$ resonances using published total cross section data. Although values of ${\Gamma }_{\gamma }$ vary widely for individual resonances, mean values of ${〈{\Gamma }_{\gamma }〉}_{l=0\mathrm{}}=750\mathrm{}\pm 150$ and ${〈{\Gamma }_{\gamma }〉}_{l=1\mathrm{}}=400\mathrm{}\pm 100$ meV were determined. The correlation between ${\Gamma }_{\gamma }$ and ${\Gamma }_n^0$ (for $s$-wave resonances) was found to give $\rho =0.64\mathrm{}\pm 0.14$ which is statistically significant at the 99.9% confidence level.

NUCLEAR REACTIONS ${}_{}{}^{55}{}_{}{}^{}\mathrm{Mn}(n, \gamma ){}_{}{}^{56}{}_{}{}^{}\mathrm{Mn}$, $E=3.0-600\mathrm{}$ keV; measured ${\sigma }_{n,\gamma }\mathrm{}\left(E\right)\mathrm{}$, deduced the resonance parameters; $E_0$, ${\Gamma }_n$, ${\left({\Gamma }_{\gamma }\right)}_l$, $S_l$, ${〈D〉}_{l=0\mathrm{}}$, ${〈D〉}_{l=1\mathrm{}}$, $\rho ({\Gamma }_n^0, {\Gamma }_{\gamma })$.

The ${}_{}{}^{51}{}_{}{}^{}\mathrm{V}(n, \gamma )$ cross section has been measured at the electron linear accelerator capture facility. This very high resolution experiment has allowed the extraction of capture areas for some 139 resonances for incident neutron energies 2.5-215 keV. The capture data combined with spin and parity assignments and a few neutron widths from the literature provide full sets ($E_{\gamma }, {\Gamma }_{\gamma }, {\Gamma }_n$) of the resonance parameters for 45 $s$-wave resonances. Analysis of these parameters has yielded values for the $s$-wave strength function ${{〈S〉}^{l=0\mathrm{}}}_{J=3\mathrm{}}=\left({8.3}_{-2.5\mathrm{}}^{+4.0\mathrm{}}\right)\times {10}^{-4\mathrm{}}$ and ${{〈S〉}^{l=0\mathrm{}}}_{J=4\mathrm{}}=\left({7.0}_{-2.2\mathrm{}}^{+3.8\mathrm{}}\right)\times {10}^{-4\mathrm{}}$ (10-90% confidence interval). The mean level spacing found for the $J^{\pi }=4^{-}$ levels is ${{〈D〉}^{l=0\mathrm{}}}_{J=4\mathrm{}}=\left({9.8}_{-0.5\mathrm{}}^{+0.8\mathrm{}}\right)$ keV. The $J^{\pi }=3^{-}$ mean level spacing ${{〈D〉}^{l=0\mathrm{}}}_{J=3\mathrm{}}=\left({7.8}_{-1.7\mathrm{}}^{+0.5\mathrm{}}\right)$ keV derived from this work is less well determined than that for the $4^{-}$ levels because of an apparent change in mean level spacing near 100 keV. This effect is probably due to levels with widths too small compared to the resolution width for parity to be determined and/or to levels not seen in this work. The $s$-wave total radiation widths are large and fluctuate widely; ${{〈{\Gamma }_{\gamma }〉}^{l=0\mathrm{}}}_{J=3\mathrm{}}=1467\mathrm{}\pm 183$ meV and ${{〈{\Gamma }_{\gamma }〉}^{l=0\mathrm{}}}_{J=4\mathrm{}}=1629\mathrm{}\pm 352$ meV. The variance of these distributions are consistent with ${\chi }^2$ distributions of 5 degrees of freedom for the $3^{-}$ resonances and 2 degrees of freedom for the $4^{-}$ resonances. The reduced neutron widths and the total radiative widths for the $4^{-}$ $s$-wave resonances exhibit strong correlation ($\rho =0.93\mathrm{}$, significant at >99.9% confidence level), but the $3^{-}$ $s$ waves are less significantly correlated ($\rho =0.42\mathrm{}$ significant at the 96% confidence level). The contribution of these resonances to the thermal capture cross section is determined to be 3.95 b, approximately 80% of the measured thermal value. The capture resonance integral derived from this work is in good agreement with the published value. The 30 keV Maxwellian averaged cross section (41±3) mb is of interest in stellar nucleosynthesis.

NUCLEAR REACTIONS ${}_{}{}^{51}{}_{}{}^{}\mathrm{V}(n, \gamma )$, $E=2.6-215\mathrm{}$ keV; measured ${\sigma }_{\gamma }\mathrm{}\left(E\right)\mathrm{}$; deduced (${}_{}{}^{51}{}_{}{}^{}\mathrm{V}$+$n$) resonance parameters, $S_0$, $D$, ${\Gamma }_{\gamma }$ for $J=3^{-}, 4^{-}$ separately, (${\Gamma }_n^0{\Gamma }_{\gamma }$) correlation coefficients significant for $J=4^{-}$, resonance integral, stellar average cross sections. 25.40.Lw

The deexcitation of high-spin states in ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$ was studied via the ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}({}_{}{}^{19}{}_{}{}^{}\mathrm{F}, 2\alpha p)$, ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}({}_{}{}^{12}{}_{}{}^{}\mathrm{C}, 2p)$, and ${}_{}{}^{34}{}_{}{}^{}\mathrm{S}(\alpha , p)$ reactions. The decay scheme and spin assignments were deduced from $p-\gamma$ coincidences, $\gamma$-ray angular distributions, directional correlation from oriented nuclei ratios, and excitation function measurements. The lifetime of a new yrast level at 7020 keV ($J=\frac{15}{2}$) was determined in a recoil distance experiment. New levels are reported at 6001 keV ($J=\frac{9}{2}-\frac{13}{2}$) and at 8177 keV. The observed levels are compared to the predictions of the weak-coupling model.

NUCLEAR REACTIONS ${}_{}{}^{34}{}_{}{}^{}\mathrm{S}(\alpha , p\gamma )$, $E=16-22\mathrm{}$ MeV, measured $p-\gamma$, $\gamma -\gamma$ coin and DCO ratios; ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}({}_{}{}^{19}{}_{}{}^{}\mathrm{F}, 2\alpha p)$, $E=45-80\mathrm{}$ MeV and ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}({}_{}{}^{12}{}_{}{}^{}\mathrm{C}, 2p)$, $E=40\mathrm{}$ MeV; measured $\gamma -\gamma$ coin, $\sigma (E_{\gamma }, \theta )$. ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$ deduced levels, $J$. Measured RDM, deduced $\tau$. Enriched ${}_{}{}^{34}{}_{}{}^{}\mathrm{S}$ targets; Ge(Li) detectors and Si telescope. Comparison with theoretical weak-coupling model.

The absolute values of ($n, 2n$) reaction cross sections around 14.5 MeV are calculated using an integrated preequilibrium-cum- statistical model. The absolute preequilibrium fraction is calculated using the Griffin-Williams exciton model as used by Braga-Marcazzan et al. in the analysis of ($n, p$) cross sections around 14 MeV. The reduction of flux for the statistical component due to the preequilibrium process has been accounted for by including both neutron and proton emission. This calculation, which is global and free from any new parameter, improves the agreement between theory and experiment reducing the 0.87 rms deviation of the statistical model to 0.48 for 88 nuclei in the mass range $60<A<\mathrm{}209\mathrm{}$. For nuclei with $A<\mathrm{}60\mathrm{}$ there is not much improvement.

NUCLEAR REACTIONS Integrated preequilibrium calculation for ($n, 2n$) cross sections for $A<\mathrm{}209\mathrm{}$. Comparison with experiment.

The ($d$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$) reaction on ${}_{}{}^{64,66,68,70}{}_{}{}^{}\mathrm{Zn}$ was investigated at $E_d=23.3\mathrm{}$ MeV and angular distributions measured for low-lying states. The mass excess of ${}_{}{}^{69}{}_{}{}^{}\mathrm{Cu}$ is found to be -65.75±0.01 MeV, about 190 keV less stable than tabulated mass values. A partial level scheme for ${}_{}{}^{69}{}_{}{}^{}\mathrm{Cu}$ based on the systematics of the ($d$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$) reaction and the energy levels of the lighter odd mass Cu isotopes is suggested. Spectroscopic factors for proton pickup from the zinc isotopes are also presented.

NUCLEAR REACTIONS ${}_{}{}^{64,66,68,70}{}_{}{}^{}\mathrm{Zn}(d, {}_{}{}^3{}_{}{}^{}\mathrm{He})$ $E_d=23.3\mathrm{}$ MeV; measured $\sigma \left(\theta \right)$, deduced $l$ DWBA analysis. ${}_{}{}^{69}{}_{}{}^{}\mathrm{Cu}$ mass measured, level scheme suggested.

Transitions between states up to spin $16\hslash$ populated in the ${}_{}{}^{146}{}_{}{}^{}\mathrm{Nd}(\alpha , 4n)$ reaction were observed using $\gamma -\gamma$ coincidence, $\gamma$-ray angular distribution and excitation function, and delayed $\gamma$-ray measurements. A level scheme was constructed up to 6.2 MeV with all levels above 3.8 MeV observed for the first time. Levels below 4.1 MeV were interpreted in terms of the coupling between two extra-core neutrons and excitations of the $N=82\mathrm{}$ core. Rotational structures and isomers were searched for above 4.1 MeV, but none were found.

NUCLEAR REACTIONS: ${}_{}{}^{146}{}_{}{}^{}\mathrm{Nd}(\alpha , 4\mathrm{n}\gamma ){}_{}{}^{146}{}_{}{}^{}\mathrm{Sm}$, E=47.9 MeV; measured ${\mathrm{E}}_{\gamma }$, ${\mathrm{I}}_{\gamma }\left(\theta \right)$, $\gamma -\gamma$ coinc., $\alpha -\gamma$ delay, ${\mathrm{E}}_{\gamma }$ vs. ${\mathrm{E}}_{\alpha }$. ${}_{}{}^{146}{}_{}{}^{}\mathrm{Sm}$ deduced levels, J, $\pi$. Ge(Li) detectors. Enriched target.

The resonant scattering of electron bremsstrahlung by an enriched sample of ${}_{}{}^{136}{}_{}{}^{}\mathrm{Ba}$ has been studied for photon energies of up to 5 MeV. It provided estimates of the radiative widths for 10 levels. Based on the relative yields at scattering angles of 96° and 126°, unambiguous spin assignments were made to 5 of these levels. Where feasible, the yield measurements were supplemented by self-absorption data and by linear polarization studies. For the strongest excitation in ${}_{}{}^{136}{}_{}{}^{}\mathrm{Ba}$, at 3.436 MeV, the resonance fluorescence experiments led to a $1^{-}$ assignment and a value ${\Gamma }_0=88\mathrm{}\pm 22$ meV for the partial width of the ground state transition. The corresponding $E1\mathrm{}$ strength is approximately $\frac{1}{3}$ of the $E1\mathrm{}$ strengths observed for the strongest low-lying $E1\mathrm{}$ transitions in the even-even $N=82\mathrm{}$ nuclei. When combined with previous observations for $N>\mathrm{}82\mathrm{}$, the result obtained for ${}_{}{}^{136}{}_{}{}^{}\mathrm{Ba}$ ($N=80\mathrm{}$) indicates that the strengths of the ground state transitions from the lowest $1^{-}$ states peak at $N=82\mathrm{}$. Yield information on a few levels in ${}_{}{}^{137}{}_{}{}^{}\mathrm{Ba}$ and ${}_{}{}^{138}{}_{}{}^{}\mathrm{Ba}$ was also obtained.

NUCLEAR REACTIONS ${}_{}{}^{136,137,138}{}_{}{}^{}\mathrm{Ba}(\gamma , \gamma )$ bremsstrahlung $1.68 \mathrm{MeV}<~E_e<~5.0 \mathrm{MeV}$; measured $\sigma \left(96\mathrm{}°\right)$ and $\sigma \left(126\mathrm{}°\right)$, self-absorption, LP; deduced $g$ $\frac{{{\Gamma }_0}^2}{\Gamma }$, $J$, $\pi$. Enriched ${}_{}{}^{136}{}_{}{}^{}\mathrm{Ba}$ target, natural target.