Recent Articles

Cluster nature and parity of the 9.155 MeV state in ${}^{15}N$

L. H. Harwood, K. W. Kemper, J. D. Fox, and A. H. Lumpkin

Phys. Rev. C 18, 2145 (1978) - Published 1 November, 1978

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The lifetime of the 9.155 MeV $J = \frac{5}{2}$ state in ${}^{15}N$ has been measured to be < 13 fsec from a study of the ${}^{12}C ({}^{7}{Li}, α γ) {}^{15}N$ reaction at $E_{{}^{7}{Li}} = 28$ MeV. The $γ$ decay from the 9.155 MeV state to the 5.30 MeV $\frac{1}{2^{+}}$ state is established as $E 2$ and thereby determines the parity of the 9.155 MeV state to be positive. Particle-gated $γ$ -ray spectra from ${}^{12}C ({}^{7}{Li}, α γ)$ and ${}^{12}C ({}^{6}{Li}, {}^{3}{He} γ)$ reactions show that the 9.155 MeV state has a large triton cluster parentage. The other member of the unresolved doublet, the 9.152 MeV $\frac{3}{2^{-}}$ state, has a very small cluster parentage. These results are in disagreement with simple ${}^{12}C$ + $t$ interpretations of ${}^{15}N$ but agree with weak coupling model calculations.

NUCLEAR STRUCTURE ${}^{12}C ({}^{6}{Li}, {}^{3}{He} γ)$ , $E = 34$ MeV; ${}^{12}C ({}^{7}{Li}, α γ)$ , $E = 34$ MeV, measured cross section to 9.155 and 9.152 MeV ${}^{15}N$ states; deduced lifetime and parity of 9.155 MeV state, compared to cluster and shell models.

${}^{12}C$ + ${}^{12}C$ resonances between $E_{c . m .} = 11 and 15$ MeV

W. Treu, H. Fröhlich, W. Galster, P. Dück, and H. Voit

Phys. Rev. C 18, 2148 (1978) - Published 1 November, 1978

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The reaction ${}^{12}C ({}^{12}C, α) {}^{20}{Ne}$ has been investigated in the energy range $E_{c . m .} = 11 - 15$ MeV. Evidence has been found for two resonances at $E_{c . m .} = 13.12 and 13.43$ MeV besides the well-known resonance at $E_{c . m .} = 11.4$ MeV. This result is in contrast to other investigations which did not yield the first two resonances but many other resonances not seen in the present experiment.

NUCLEAR REACTIONS ${}^{12}C ({}^{12}C, α)$ , $E = 11 - 15$ MeV (c.m.), measured $σ (⊖, E)$ . Resonances observed at $E_{c . m .} = 11.4, 13.12, and 13.43$ MeV.

Systematics of fusion barriers obtained with a modified proximity potential

Louis C. Vaz and John M. Alexander

Phys. Rev. C 18, 2152 (1978) - Published 1 November, 1978

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A systematic semiempirical analysis is presented for excitation functions for complete fusion of complex nuclei. Barrier penetration is included as is the $l$ dependence of the fusion radius. The general form of the proximity potential is assumed and small but important parameter adjustments are made to achieve a fit to experimental data. A correction is presented of $s$ -wave barrier heights and radii for complete fusion. For $Z_{t} Z_{p} < 500$ these fusion radii are greater than the empirical reaction radii obtained at energies well above the barrier. This result implies weak surface absorption for $Z_{t} Z_{p} < 500$ and the contrary for higher $Z_{t} Z_{p}$ .

NUCLEAR REACTIONS Semiempirical analysis of complete fusion excitation functions with a modified proximity potential; correlation between $s$ -wave barrier heights and fusion radii; fusion radii exceed empirical interaction radii for $Z_{t} Z_{p} < 500$ and the contrary.

Linear polarization measurements of $γ$ rays from ${}^{64}{Zn}$

J. C. Wells, Jr., R. L. Robinson, H. J. Kim, R. O. Sayer, A. J. Caffrey, and R. B. Piercey

Phys. Rev. C 18, 2162 (1978) - Published 1 November, 1978

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The linear polarizations of ${}^{64}{Zn}$ $γ$ rays, produced in the ${}^{59}{Co} ({}^{7}{Li}, 2 n)$ reaction with $E_{{}^{7}{Li}} = 18$ MeV, have been measured with a Ge(Li) two-crystal Compton polarimeter. These polarization values were used with previously obtained $γ$ -ray angular distribution measurements to make unique parity assignments for several states. The 641- and 1619-keV $γ$ rays have been found to be predominantly $E 1$ transitions, and odd parity has been assigned to the levels at 2999 keV ( $3^{-}$ ), 3925 keV ( $5^{-}$ ), 4635 keV ( $7^{-}$ ), 4981 keV ( $7^{-}$ ), and 5681 keV ( $8^{-}$ ). Even parity assignments have been confirmed for levels at 991 keV (2+), 2736 keV (4+), 3994 keV (6+), and 4237 keV (6+). Also, the spin assignments for levels at 2307 keV (4+) and 4635 keV ( $7^{-}$ ) have been confirmed.

NUCLEAR REACTIONS ${}^{59}{Co} ({}^{7}{Li}, 2 n) {}^{64}{Zn}$ , $E = 18$ MeV; measured linear polarization of $γ$ rays; deduced parities and multipole mixing ratios in ${}^{64}{Zn}$ .

Properties of high spin states in the ${(π f_{\frac{7}{2}})}^{\pm 3}$ nuclei ${}^{51}V$ and ${}^{53}{Mn}$

C. J. Lister, J. W. Olness, and I. P. Johnstone

Phys. Rev. C 18, 2169 (1978) - Published 1 November, 1978

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The ${}^{48}{Ca} ({}^{10}B, α 3 n) {}^{51}V$ and ${}^{48}{Ca} ({}^{10}B, 5 n) {}^{53}{Mn}$ reactions have been used to populate high spin states in ${}^{51}V$ and ${}^{53}{Mn}$ . New levels were observed at 7335 keV in ${}^{51}V$ , with a probable spin of $J = \frac{23}{2}$ and at 5614, 6533, 7004, and 7965 keV in ${}^{53}{Mn}$ with a probable spin sequence of $J = \frac{19}{2}, \frac{21}{2}, \frac{23}{2}, and \frac{25}{2}$ , respectively. The Doppler shift attenuation method was used to measure the mean lifetimes of four levels in ${}^{51}V$ and three in ${}^{53}{Mn}$ . The high spin states were found to decay predominantly by $M 1$ transitions, while competing $E 2$ decays were not significantly enhanced, revealing no evidence of any collective deformation. Shell model calculations of 1p-6h states in ${}^{51}V$ and 1p-4h states in ${}^{53}{Mn}$ were found to indicate that these excited states are based mainly on neutron excitation from the $f_{\frac{7}{2}}$ shell. The calculations reproduced both the positions of the yrast energy levels and their electromagnetic decays.

NUCLEAR REACTIONS ${}^{48}{Ca} ({}^{10}B, α 3 n)$ , ${}^{48}{Ca} ({}^{10}B, 5 n)$ , $E = 25 - 50$ MeV. Measured $σ (E)$ , $γ - γ$ coinc, $I (θ)$ . Deduced levels, branching ratios, $J^{π}$ assignments, DSAM lifetimes. Enriched targets, Ge(Li) detectors. Comparison with shell model calculations.

One and two-step processes in stripping and pick-up reactions induced by ${}^{15}N$ on ${}^{28}{Si}$

J. C. Peng, B. T. Kim, M. C. Mermaz, A. Greiner, and N. Lisbona

Phys. Rev. C 18, 2179 (1978) - Published 1 November, 1978

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The neutron stripping and proton pickup reactions induced by a 44 MeV ${}^{15}N$ beam on a ${}^{28}{Si}$ target have been studied. The data were analyzed in terms of the distorted-wave Born approximation. The coupled channel effects were also examined. The calculations reproduce well the shape of the observed angular distributions and the relative intensities. It is also found that the two-step processes involving core excitation of the target and residual nucleus play an important role in populating some excited states in the residual nucleus. However, the absolute magnitudes of the cross sections of the proton pickup reaction are not given by these approaches.

NUCLEAR REACTIONS ${}^{28}{Si}$ ( ${}^{15}N$ , ${}^{14}N$ ) ${}^{29}{Si}$ and ${}^{28}{Si}$ ( ${}^{15}N$ , ${}^{16}O$ ) ${}^{27}{Al}$ ; $E_{{}^{15}N} = 44$ MeV, angular distributions measured between 5° and 29° lab; DWBA and CCBA analysis.

${}^{59}{Co}$ ( ${}^{16}O$ , ${}^{16}O$ ) ${}^{59}{Co}$ elastic scattering

N. B. J. Tannous, J. F. Mateja, D. C. Wilson, L. R. Medsker, and R. H. Davis

Phys. Rev. C 18, 2190 (1978) - Published 1 November, 1978

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Differential cross sections for the ${}^{59}{Co}$ ( ${}^{16}O$ , ${}^{16}O$ ) ${}^{59}{Co}$ elastic scattering have been measured at laboratory energies 36, 40, 45.5, 49, 52, and 56 MeV. The angular range was 15°-170° (lab) in 5° steps at lower energies. At higher energies detailed angular distributions were carried out in 1° steps until the ratio to Rutherford was < $10^{- 3}$ with sample measurements at larger angles to assure that the differential cross sections were less than $10^{- 4}$ ratio to Rutherford. The data have been analyzed with a four parameter optical model and the continuous ambiguities in this model are discussed. Strong absorption radii and the values of the nuclear potentials at these points are determined. Good fits to the data have been obtained using a $G$ -matrix double-folding model with double-folded or Woods-Saxon forms for the imaginary potential. The required normalization of the real double-folded potential is near unity for all energies. Total reaction cross sections have been obtained by the optical model, quarter-point, "half partial-wave," and the sum of differences methods. The sum of differences method gives slightly larger total reaction cross sections than do the other methods by an amount consistent with estimates of the Coulomb excitation cross section. Estimates of the errors in the sum of differences values are computed by applying the optical theorem and are shown to be negligibly small.

NUCLEAR REACTIONS: ${}^{59}{Co}$ ( ${}^{16}O$ , ${}^{16}O$ ) ${}^{59}{Co}$ ; measured $σ (θ, E)$ , $E_{lab} = 36, 40, 45.5, 49, 52, and 56$ MeV; measured total reaction cross sections.

Gamma decays of 2.97-MeV doublet in ${}^{20}F$

J. C. Legg, D. J. Crozier, G. G. Seaman, and H. T. Fortune

Phys. Rev. C 18, 2202 (1978) - Published 1 November, 1978

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The new member of the 2.97-MeV doublet in ${}^{20}F$ has a dominant $γ$ decay to a ( $3^{-}$ ) state at 1971 keV, further evidence that the new state has $J^{π} = (4^{-})$ . The excitation energy is 2968.0±1.5 keV.

NUCLEAR REACTION ${}^{11}B ({}^{13}C, α γ)$ , $E = 18.5$ MeV; measured $E_{α}$ , $E_{γ}$ , $α γ$ coincidences. ${}^{20}F$ deduced levels, gamma branchings, $J$ , $π$ .

${}^{58}{Ni}$ ( ${}^{16}O$ , ${}^{12}C$ ) ${}^{62}{Zn}$ reaction at 46 and 60 MeV incident energy

G. P. A. Berg, B. Berthier, J. P. Fouan, J. Gastebois, J. P. Le Fèvre, and M. -C. Lemaire

Phys. Rev. C 18, 2204 (1978) - Published 1 November, 1978

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Cross section angular distributions for the ${}^{16}O$ elastic scattering on ${}^{58}{Ni}$ at an incident energy of $E_{{}^{16}O} = 60$ MeV and the ${}^{58}{Ni}$ ( ${}^{16}O$ , ${}^{12}C$ ) ${}^{62}{Zn}$ reaction leading to the strongly excited states at 0.0 MeV, 0.95 MeV, and 3.19 MeV at $E_{{}^{16}O} = 46 MeV and 60 MeV$ have been measured. Six different sets of optical model parameters are able to reproduce equally well the measured cross section angular distribution of the oxygen elastic scattering. The EFR-DWBA analysis of the ( ${}^{16}O$ , ${}^{12}C$ ) results shows that only one set of surface transparent optical model parameters predicts the ( ${}^{16}O$ , ${}^{12}O$ ) angular distributions at $E_{{}^{16}O} = 60$ MeV, while no optical potential was able to provide good fits to the 46 MeV data. The position of the maxima of the "bell shaped" angular distributions at 46 MeV are shifted to forward angles compared to the DWBA calculations. Relative spectroscopic factors obtained from comparison of data and calculations will be compared to previous ( ${}^{6}{Li}$ , $d$ ) results. Using a $Q 3 D$ magnetic spectrograph an energy spectrum resolution of 60 keV was obtained for the ${}^{58}{Ni}$ ( ${}^{16}O$ ${}^{12}C$ ) ${}^{62}{Zn}$ reaction and 13 energy levels are identified in the excitation energy range from 3.19 to 6.30 MeV.

NUCLEAR REACTIONS ${}^{58}{Ni}$ ( ${}^{16}O$ , ${}^{16}O$ ), $E_{{}^{16}O} = 60$ MeV; ${}^{58}{Ni}$ ( ${}^{16}O$ , ${}^{12}C$ ), $E_{{}^{16}O} = 46 MeV and 60 MeV$ ; measured $σ (θ)$ , $θ_{lab} = 14 ° - 84 °$ for ( ${}^{16}O$ , ${}^{16}O$ ) and $θ_{lab} = 3 ° - 36 °$ for ( ${}^{16}O$ , ${}^{12}C$ ), $Δ θ_{lab} = 1 °$ ; deduced optical model parameters from elastic scattering; EFR-DWBA analysis; identified 13 energy levels in ${}^{62}{Zn}$ between $E_{x} = 3.19 MeV and 6.30 MeV$ , resolution 60 keV.

Scission-point configurations in ternary fission of ${}^{252}{Cf}$ from trajectory calculations

R. K. Choudhury and V. S. Ramamurthy

Phys. Rev. C 18, 2213 (1978) - Published 1 November, 1978

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Trajectory calculations have been carried out in a three-point- charge model for the case of spontaneous ternary fission of ${}^{252}{Cf}$ with a view to obtain the initial parameters characterizing the scission configuration. Without any a priori assumptions regarding the distribution of the points of emission of the $α$ particle and the fragment velocity at the time of scission, the values of the initial parameters were obtained by fitting the observed energy distributions by making use of the method of multivariate analysis. It was found that there exist two points of $α$ particle emission, nearer to either of the two fragments and off the axis joining the fragment centers, which reproduce the experimental distributions equally well. This result does not support the often made assumption that the point of $α$ particle emission coincides with the potential energy minimum on the line joining the fragment centers. With the initial parameters thus obtained, an inverse Monte Carlo calculation was carried out to obtain various correlations between the final values of the energy and the angle of emission of the $α$ particle and the fission fragment kinetic energy. The calculated results agree well with the experiments. The implication of present results on the emission mechanism of the $α$ particle in ternary fission is discussed.

NUCLEAR REACTIONS, FISSION Ternary fission ${}^{252}{Cf}$ , trajectory calculations, scission configuration.

Electropion production in ${}^{3}{He}$ determined by measuring the triton recoil cross section

D. M. Skopik, E. L. Tomusiak, J. Asai, and J. J. Murphy, II

Phys. Rev. C 18, 2219 (1978) - Published 1 November, 1978

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The ${}^{3}{He} (e, t) π^{+}$ , $e^{'}$ cross section has been measured as a function of incident electron energy, triton recoil energy, and angle. The experiment corresponds to excitation energies near 20 MeV above pion threshold. Comparison is made with a theory including all partial waves using Gaussian and Irving-Gunn ground states for ${}^{3}{He}$ . The forward peaking approximation is also discussed.

NUCLEAR REACTIONS ${}^{3}{He} (e, t) π^{+}$ , $e^{'}$ , measured $σ (E_{t}, θ_{t}, E_{0})$ compared with electropion production theory.

Quadrupole scattering of pions by ${}^{9}{Be}$

D. F. Geesaman, C. Olmer, B. Zeidman, R. L. Boudrie, R. H. Siemssen, J. F. Amann, C. L. Morris, H. A. Thiessen, G. R. Burleson, M. J. Devereux, R. E. Segel, and L. W. Swenson

Phys. Rev. C 18, 2223 (1978) - Published 1 November, 1978

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The results for $π^{\pm}$ + ${}^{9}{Be}$ elastic scattering at $E_{lab} = 162$ MeV are shown to provide evidence for quadrupole contributions to the elastic scattering of pions. The strong-coupling rotational model is used to relate the measured inelastic scattering cross sections to the elastic scattering cross sections.

INTERMEDIATE ENERGY $π^{\pm}$ + ${}^{9}{Be}$ elastic and inelastic scattering, $E_{lab} = 162$ MeV, optical-model analysis, quadrupole scattering.

Statistics of the fireball model

G. Mantzouranis

Phys. Rev. C 18, 2227 (1978) - Published 1 November, 1978

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We derive the fireball model using a parametrization of the exact $S$ matrix. It will be shown that the fireball model is related to the normal distribution of the parameters in the $S$ -matrix expansion. This way the fireball will be understood in the same frame as the usual statistical spectrascopy.

NUCLEAR REACTIONS Relativistic heavy ions; theory of the fireball model

Emission of ${}^{24}{Na}$ fragments in the interaction of ${}^{197}{Au}$ with intermediate-energy pions and protons

N. T. Porile, B. J. Dropesky, and R. A. Williams

Phys. Rev. C 18, 2231 (1978) - Published 1 November, 1978

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Excitation functions for the formation of ${}^{24}{Na}$ from ${}^{197}{Au}$ have been measured for incident $π^{+}$ between 176 and 368 MeV, $π^{-}$ between 239 and 368 MeV, and protons between 197 and 800 MeV. The cross sections increase sharply with energy and at any given energy obey the relation $σ_{π +} > σ_{π -} > σ_{p}$ . The results are analyzed in terms of the contribution of hot-spot and coherent-cascade mechanisms to the proton yields. The role of statistical phase-space factors, as embodied in cascade-evaporation calculations, is invoked to explain the ratio of $π^{+}$ and $π^{-}$ cross sections.

NUCLEAR REACTIONS ${}^{197}{Au} (p, x)$ , $E_{p} = 197 - 800$ MeV; ${}^{197}{Au} (π^{+}, x)$ , $E_{π^{+}} = 176 - 368$ MeV; ${}^{197}{Au} (π^{-}, x)$ , $E_{π^{-}} = 239 - 368$ MeV; ${}^{24}{Na}$ excitation functions.

Spallation of Cu by 500- and 1570-MeV $π^{-}$

P. E. Haustein and T. J. Ruth

Phys. Rev. C 18, 2241 (1978) - Published 1 November, 1978

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Relative yields of 36 products extending from ${}^{7}{Be}$ to ${}^{65}{Zn}$ have been measured for the interaction of 500-and 1570-MeV negative pions with Cu. These results are compared with calculations from the ISOBAR model, with earlier studies of Cu spallation with lower (resonance) energy pions, energetic protons, and heavy ions. Relative yield patterns at both $π^{-}$ energies show only slight differences when compared to spallation by protons of comparable energy. Calculations from the ISOBAR model adequately reproduce the shapes of the mass yield and charge yield of the experimental data for 500-MeV $π^{-}$ . The calculation, however, overestimates the yield of neutron-rich isotopes from deep spallation. At the 1570-MeV $π^{-}$ energy the yield patterns, charge-dispersion, and mass-yield curves are nearly identical to those for 2-GeV proton spallation. These results suggest that pion-nucleon resonance effects probably decrease at higher energies and that limiting fragmentation and factorization concepts may be applied to understanding high-energy pion spallation.

NUCLEAR REACTIONS $Cu (π^{-}, spallation)$ , $E_{π^{-}} = 500 and 1570$ MeV, measured relative $σ (A, Z)$ , products ${}^{7}{Be}$ - ${}^{65}{Zn}$ . Deduced charge-dispersion and mass-yield curves. Comparison with intranuclear cascade and evaporation calculations. Natural targets, Ge(Li) detectors, radiochemistry.

Isospin nonconservation in the $N - N$ interaction

A. Gersten

Phys. Rev. C 18, 2252 (1978) - Published 1 November, 1978

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A relativistic formalism of the $N - N$ scattering including the electromagnetic contributions is presented. Relativistic electro- magnetic phase shifts are defined and evaluated. The difference between the nuclear phase shifts of the $p - p$ and $n - p$ interactions is evaluated taking into account the interference between strong and Coulomb forces, electromagnetic $n - p$ contributions and the mass differences between the charged and neutral pions. The $n - p$ interaction is described with the aid of six amplitudes. Neutron- proton observables are calculated with these six amplitudes. The mixing angle of the singlet-triplet transitions is evaluated. Experiments which should show these transitions are discussed.

NUCLEAR REACTIONS $N - N$ interaction, electromagnetic effects, isospin non-conservation.

Radiative muon capture rates and the maximum photon energy

R. S. Sloboda and Harold W. Fearing

Phys. Rev. C 18, 2265 (1978) - Published 1 November, 1978

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The differential photon spectrum for radiative muon capture is expanded about the average maximum photon energy $k_{m}$ and the correction terms evaluated using for one a modified Thomas-Reiche-Kuhn sum rule, thus extending previous work for ordinary capture. The resulting rate is much less dependent on $k_{m}$ than the usual closure result. The ratio $\frac{k_{m}}{ν}$ appropriate for closure calculations, with $ν$ the average neutrino energy, is determined and found to be approximately constant and, when correction terms are included, somewhat higher than values previously used. By similar techniques a consistency relation is derived which can be solved to explicitly estimate "physical" values of $k_{m}$ and $ν$ .

NUCLEAR REACTIONS Radiative muon capture. Differential photon spectrum, relative rate for ${}^{40}{Ca}$ . Dipole sum rules used to correct closure approximation, obtain estimates of mean excitation energy, average maximum photon energy.

Nucleus-nucleus total cross sections for light nuclei at 1.55 and 2.89 GeV/c per nucleon

J. Jaros, A. Wagner, L. Anderson, O. Chamberlain, R. Z. Fuzesy, J. Gallup, W. Gorn, L. Schroeder, S. Shannon, G. Shapiro, and H. Steiner

Phys. Rev. C 18, 2273 (1978) - Published 1 November, 1978

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We have measured total cross sections for protons, dueterons, $α$ particles, and ${}^{12}C$ on hydrogen, deuterium, helium, and carbon targets at 1.55 and 2.89 GeV/c nucleon using the "good geometry" transmission method. In addition, we measured the inelastic cross sections and elastic slope parameters for reactions initiated by deuterons, $α$ particles, and ${}^{12}C$ . Our results are in good agreement with Glauber theory predictions, but the factorization relation $σ_{T} (AA) = \frac{{[σ_{T} (AB)]}^{2}}{σ_{T} (BB)}$ is not a good guide. We find $σ_{T} ≃ 144 {({A_{T}}^{\frac{1}{3}} - {A_{p}}^{\frac{1}{3}} - 1.48)}^{2}$ mb and $σ_{IN} ≃ 78 {({A_{T}}^{\frac{1}{3}} + {A_{p}}^{\frac{1}{3}} - 1.25)}^{2}$ mb, where $A_{T} (A_{p})$ is the atomic mass number of the target (projectile).

NUCLEAR REACTIONS ${}^{12}C ({}^{12}C, X)$ , ( $α, X$ ), ( $d, X$ ), ( $p, X$ ), $E = 0.87 and 2.10$ GeV/nucleon; measured total cross section, total inelastic cross section, and slope parameter of elastic scattering.

Inclusive quasielastic deuteron production

E. A. Remler and A. P. Sathe

Phys. Rev. C 18, 2293 (1978) - Published 1 November, 1978

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It is argued that the measurement of the inclusive quasielastic deuteron production cross section coming from intermediate energy nucleus bombarding nuclei is of considerable theoretical interest. The inclusivity of the measurement leads to simplifications and allows a quasiclassical description to be used. A simple, heuristic, and quantum mechanically well defined formula is derived which includes for the first time a realistic treatment of the multiple scattering complications inherent in the problem. A rough calculation based on this formula gives reasonable agreement with the limited data available. We conclude that the observed number of deuterons does not require nuclear clustering and that the reaction is not highly peripheral. We believe that this and related reactions offer a greater possibility of yielding information on nuclear correlation than had been supposed. The theory of this reaction is shown to be fundamentally related to recent quasiclassical theories of heavy ion collisions.

NUCLEAR REACTIONS General discussion of inclusive reaction theories. Relation to classical theories and statistical mechanics. Application to quasi-elastic deuteron production data. Dependence on energy, angle and nucleus.

Elastic pion scattering from ${}^{6, 7}{Li}$ and ${}^{12, 13}C$

S. A. Dytman, J. F. Amann, P. D. Barnes, J. N. Craig, K. G. R. Doss, R. A. Eisenstein, J. D. Sherman, W. R. Wharton, G. R. Burleson, S. L. Verbeck, R. J. Peterson, and H. A. Thiessen

Phys. Rev. C 18, 2316 (1978) - Published 1 November, 1978

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Elastic scattering of 50 MeV $π^{+}$ projectiles from targets of ${}^{6, 7}{Li}$ and ${}^{12, 13}C$ has been studied. Effects due to isotopic differences between targets are clearly visible in the data. The results are compared to three model descriptions for the cross section ratios for isotope pairs; in the case of ${}^{12}C$ - ${}^{13}C$ a simple core-plus-valence-neutron model works well for ${}^{13}C$ if the core ( ${}^{12}C$ ) potential describes observed ${}^{12}C$ elastic scattering. Such a model does not work for the ${}^{6}{Li}$ - ${}^{7}{Li}$ ratio due to improper treatment of the scattering process and the quadrupole moments of the Li ground states.

NUCLEAR REACTIONS Elastic scattering of 50 MeV $π^{+}$ from enriched ${}^{6}{Li}$ , ${}^{7}{Li}$ , ${}^{12}C$ , and ${}^{13}C$ . Angular distributions: $30 ° \leq θ_{L} \leq 145 °$ . Optical model analysis of differences in scattering due to isotopic effects.

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Cluster nature and parity of the 9.155 MeV state in ${}^{15}N$

${}^{12}C$ + ${}^{12}C$ resonances between $E_{c . m .} = 11 and 15$ MeV

Systematics of fusion barriers obtained with a modified proximity potential

Linear polarization measurements of $γ$ rays from ${}^{64}{Zn}$

Properties of high spin states in the ${(π f_{\frac{7}{2}})}^{\pm 3}$ nuclei ${}^{51}V$ and ${}^{53}{Mn}$

One and two-step processes in stripping and pick-up reactions induced by ${}^{15}N$ on ${}^{28}{Si}$

${}^{59}{Co}$ ( ${}^{16}O$ , ${}^{16}O$ ) ${}^{59}{Co}$ elastic scattering

Gamma decays of 2.97-MeV doublet in ${}^{20}F$

${}^{58}{Ni}$ ( ${}^{16}O$ , ${}^{12}C$ ) ${}^{62}{Zn}$ reaction at 46 and 60 MeV incident energy

Scission-point configurations in ternary fission of ${}^{252}{Cf}$ from trajectory calculations

Electropion production in ${}^{3}{He}$ determined by measuring the triton recoil cross section

Quadrupole scattering of pions by ${}^{9}{Be}$

Statistics of the fireball model

Emission of ${}^{24}{Na}$ fragments in the interaction of ${}^{197}{Au}$ with intermediate-energy pions and protons

Spallation of Cu by 500- and 1570-MeV $π^{-}$

Isospin nonconservation in the $N - N$ interaction

Radiative muon capture rates and the maximum photon energy

Nucleus-nucleus total cross sections for light nuclei at 1.55 and 2.89 GeV/c per nucleon

Inclusive quasielastic deuteron production

Elastic pion scattering from ${}^{6, 7}{Li}$ and ${}^{12, 13}C$

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