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13.9 MeV neutron spin flip in ${}^{32}S$ $2^{+}$ (2.23 MeV) excitation

R. De Leo, G. D'Erasmo, E. M. Fiore, A. Pantaleo, and G. Pasquariello

Phys. Rev. C 22, 337(R) (1980) - Published 1 July, 1980

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The spin-flip probability for 13.9 MeV neutron inelastic scattering to the $2^{+}$ (2.23 MeV) level of ${}^{32}S$ has been determined by measuring the neutron time-of-flight spectrum in coincidence with the deexcitation $γ$ radiation emitted perpendicularly to the reaction plane. A comparison has been made between neutron and proton spin-flip probabilities at nearby incident energies.

NUCLEAR REACTION ${}^{32}S (n, n^{'} γ)$ , $E_{n} = 13.9$ MeV, measured $n^{'} γ (θ_{n^{'}})$ coincidences and deduced neutron spin-flip probability. Macroscopic $CC$ analyses. Natural target.

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Nonstatistical structure in ${}^{12}C ({}^{14}N, α) {}^{22}{Na}$

L. C. Dennis and S. T. Thornton

Phys. Rev. C 22, 340(R) (1980) - Published 1 July, 1980

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Correlated structure has been found in the forward-angle excitation functions of the ${}^{12}C ({}^{14}N, α) {}^{22}{Na}$ reactions. An attempt is made based on the strong correlations observed to determine the origin of the structure. It is found that several explanations including statistical fluctuations, direct mechanisms, and the population of isolated high-spin yrast states are unlikely.

NUCLEAR REACTIONS ${}^{12}C ({}^{14}N, α) {}^{22}{Na}$ ; $E_{c . m .} = 10.1 - 15.9$ MeV, $θ = 75 °$ ; correlated nonstatistical structure found; resonances discussed.

Backward angle anomaly in inelastic alpha scattering from calcium isotopes

Shigeo Ohkubo

Phys. Rev. C 22, 36 (1980) - Published 1 July, 1980

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Anomalous angular distributions of inelastic $α$ -particle scattering from ${}^{40}{Ca}$ , ${}^{42}{Ca}$ , ${}^{44}{Ca}$ , and ${}^{48}{Ca}$ have been analyzed with a parity dependent potential model. The results of a coupled channel analysis with the potential that was determined in the study of backward angle anomaly in elastic scattering are in significantly better agreement with the experimental angular distributions at 24 and 29 MeV than those obtained with the ordinary optical model.

NUCLEAR REACTIONS inelastic scattering, $α$ + ${}^{40, 42, 44, 48}{Ca}$ , $E_{α} = 24, 29$ MeV, backward angle anomaly, parity dependent potential model analysis, coupled channel calculations.

Analyzing power measurements for two-nucleon transfer reactions in a shape transitional nucleus

E. R. Flynn, Ronald E. Brown, J. A. Cizewski, J. W. Sunier, W. P. Alford, E. Sugarbaker, and D. Ardouin

Phys. Rev. C 22, 43 (1980) - Published 1 July, 1980

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Measurements of the analyzing power in the two-nucleon transfer reaction ( $\vec{t}, p$ ) have been carried out leading to ${}^{98}{Mo}$ and to the transitional nucleus ${}^{102}{Mo}$ where shape coexistence states are expected. Because of the sensitivity of the shapes of analyzing powers to the reaction mechanism, such data may be useful in determining the basic parentage of excited states in these nuclei through the interference of second order processes. A comparison of the ground state and strong excited $0^{+}$ state transitions shows no large differences in the shapes of analyzing powers nor are any observed in $L = 2$ transitions.

NUCLEAR REACTIONS ${}^{96, 100}{Mo} (\vec{t}, p)$ $E = 17$ MeV; polarized beam; enriched targets: measured $σ (E_{p}, θ)$ , $A_{y} (θ)$ ; DWBA; transitional nucleus description.

Evidence for nuclear shape coexistence at $N = 88$ : ${}^{152}{Eu} (d, p)$ and ( $d, t$ ) reactions

Robert G. Lanier, Gordon L. Struble, Lloyd G. Mann, Ivan C. Oelrich, Ivan D. Proctor, and Dale W. Heikkinen

Phys. Rev. C 22, 51 (1980) - Published 1 July, 1980

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The ( $d, p$ ) and ( $d, t$ ) reactions on an isotopically enriched radioactive target of ${}^{152}{Eu}$ were investigated at a deuteron bombarding energy of 20 MeV. The triton spectrum showed the following features: (1) levels in ${}^{151}{Eu}$ below ∼ 260 keV were virtually unpopulated, (2) the pickup strength of one-quasiparticle states is severely fragmented and is spread over a group of levels between ∼ 260 and ∼ 950 keV, and (3) the majority of the pickup strength is concentrated in a narrow band of levels between ∼ 2.3 and ∼ 2.8 MeV. An analysis of these data in conjunction with other available information on the structure of ${}^{151}{Eu}$ suggests the coexistence of three distinct shapes in ${}^{151}{Eu}$ : states related to the ground state are spherical, states related to a $\frac{5}{2^{+}}$ state at 260 keV are moderately deformed, and states between ∼ 2.3 and ∼ 2.8 MeV are strongly deformed and are essentially one-neutron holes coupled to a two-quasiparticle configuration which is identical to the ground state structure of ${}^{152}{Eu}$ . The spectrum observed in the ( $d, p$ ) reaction shows that the ${}^{153}{Eu}$ $\frac{5}{2^{+}}$ ground state rotational band is weakly populated to $I = \frac{11}{2}$ , but shows few other states below ∼ 2 MeV. The intensity patterns and angular distributions for the ${}^{153}{Eu}$ ground band are consistent with pure $l = 5$ transfer to the ${}^{152}{Eu}$ ${π \frac{5}{2} [413], ν \frac{11}{2} [505]}_{K = 3}$ ground state.

NUCLEAR REACTIONS ${}^{152}{Eu} (d, p)$ and ( $d, t$ ) with isotopically enriched radioactive target; $E_{d} = 20$ MeV; measured $E_{p}$ , $E_{t}$ , and $σ (θ)$ with Q3D spectrograph; DWBA analysis, deduced levels, $J^{π}$ .

NUCLEAR STRUCTURE ${}^{151}{Eu}$ and ${}^{153}{Eu}$ assigned Nilsson configurations; shape coexistence in ${}^{151}{Eu}$ .

Properties of the 2p-1h intermediate structure in ${}^{41}{Sc}$

P. H. Wallace, H. J. Hausman, H. R. Suiter, and R. L. West

Phys. Rev. C 22, 65 (1980) - Published 1 July, 1980

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Angular correlations in the ${}^{40}{Ca} (p, p^{'} γ) {}^{40}{Ca}^{*}$ (3.73 MeV) have been measured for a group of levels centered at an excitation energy of 7.2 MeV in ${}^{41}{Sc}$ . Analyzing-power measurements have also been made over the same resonances in the elastic channel. The spin of 6 of the resonances which preferentially decayed to the 1p-1h $3^{-}$ state in ${}^{40}{Ca}$ have been measured as being $\frac{5}{2^{+}}$ . The results are interpreted as being evidence for a 2p-1h intermediate structure in ${}^{41}{Sc}$ formed by the coupling of a particle in the $2 p$ shell to the $3^{-}$ core state in ${}^{40}{Ca}$ . Evidence is presented for a resonance in ${}^{41}{Sc}$ which is a possible candidate for being the $T = \frac{3}{2}$ , $T_{z} = - \frac{1}{2}$ member of the quartet of states built upon the second excited $\frac{7}{2^{-}}$ state in ${}^{41}K$ .

NUCLEAR REACTIONS ${}^{40}{Ca} (p, p^{'} γ) {}^{40}{Ca}^{*}$ , $E_{p} = 6.02 - 6.48$ MeV. ${}^{40}{Ca} (\vec{p}, p_{0}) {}^{40}{Ca}$ analyzing-power measurements. $E_{p} = 6.0 - 6.4$ MeV. Deduced spins and parities of 12 resonances. Natural target.

Reaction ${}^{3}{He} (γ, 2 p) n$ at intermediate photon energies

F. Prats, E. P. Harper, and L. C. Maximon

Phys. Rev. C 22, 7 (1980) - Published 1 July, 1980

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Proton energy distributions and the differential cross section for the reaction ${}^{3}{He} (γ, 2 p) n$ for incident photon energies between 80 and 120 MeV have been calculated. In order to compare with available experimental data, we consider the situation in which both protons emerge close to a direction perpendicular to the incident photon beam. It is shown that in that case the dominant contribution is given by the direct breakup of ${}^{3}{He}$ into a free neutron and an interacting singlet $p - p$ pair. The nucleon momentum distribution in ${}^{3}{He}$ used in the calculation is obtained from a phenomenological fit to momentum distributions observed in quasifree ( $p, 2 p$ ) scattering experiments on ${}^{3}{He}$ . If the Coulomb interaction between protons is ignored, the calculated energy distribution agrees, at lower photon energies (∼ 50 MeV), with previous calculations in which the nuclear interaction was included fully in the final state, but only the dipole electromagnetic operator was included. The Coulomb interaction changes the shape of the proton energy distribution completely, bringing it and the differential cross section into agreement with the experimental data.

NUCLEAR REACTIONS Three-nucleon photodisintegration of ${}^{3}{He}$ ; intermediate energy calculation; Coulomb effects.

Angular distributions in a unified model of preequilibrium and equilibrium neutron emission

J. M. Akkermans, H. Gruppelaar, and G. Reffo

Phys. Rev. C 22, 73 (1980) - Published 1 July, 1980

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An alternative mathematical formulation is presented for the generalized master equation of the exciton model, introduced by Mantzouranis et al. to describe preequilibrium effects in angular distributions of emitted particles in nuclear reactions. The exciton model proposed in this paper includes internal transitions with $Δ n = 2, 0, - 2$ , and describes both the preequilibrium and the equilibrium stages of the reaction process. A simple, but exact formula is given to calculate mean lifetimes of exciton states and their Legendre coefficients, from which double differential cross sections can be easily calculated. The mathematical improvements of the generalized exciton model greatly facilitate a systematical comparison with experimental data. In this paper the neutron inelastic scattering data for 34 elements measured by Hermsdorf et al. at 14.6 MeV were used for such intercomparison. The results show underestimation of angular distributions at backward angles. However, a good overall fit of all angular distributions is obtained by adjustment of only two global parameters. It is concluded that further study with regard to the physics of the model is required. Some local variations in the angular distribution coefficients as a function of the mass number might be ascribed to level-density effects. Although it appeared that the presently adopted formulas and parameters in exciton model calculations are not adequate to give detailed predictions of the energy and angular distributions, meaningful improvements were obtained by variation of final-state parameters. Finally, some attention was devoted to the unification of the exciton and Hauser-Feshbach models. By introducing a proper definition of "equilibrium" emission it is shown that consistent results are obtained for neutron emission spectra calculated with the two models.

NUCLEAR REACTIONS Be, C, Na, Mg, Al, Si, P, S, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Se, Br, Zr, Nb, Cd, In, Sn, Sb, I, Ta, W, Au, Hg, Pb, Bi ( $n, nx$ ), $E = 14.6$ MeV; calculated $σ$ ( $E_{n}, θ$ ), Legendre coefficients. Generalized exciton model, preequilibrium and equilibrium analysis, Hauser-Fesh-bach model.

Radial sensitivity of elastic scattering

John G. Cramer and Ralph M. DeVries

Phys. Rev. C 22, 91 (1980) - Published 1 July, 1980

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A new technique has been developed, employing a localized perturbation of the radial nuclear optical potential, which permits direct investigation of the sensitivities of optical model analysis of elastic scattering data to the details of the radial potential. It is found that both light- and heavy-ion scattering probe primarily the nuclear surface region. Higher energy scattering data probe further into the interior than lower energy data. The value of the potential at the center of the nucleus cannot be determined, but only inferred if a fixed parametrization such as Woods-Saxon geometry is specified. In addition, it is found that the region of radial sensitivity of the imaginary potential is systematically closer to the center of the nucleus than is that of the real potential.

NUCLEAR REACTIONS Radial sensitivity of optical model calculations to elastic $σ (θ)$ data analyzed for $p$ + ${}^{12}C$ , $α$ + ${}^{58}{Ni}$ , ${}^{16}O$ + ${}^{28}{Si}$ at low and intermediate incident energies.

Magnetic moments of the $2_{1}^{+}$ levels in even Sn isotopes

M. Hass, C. Broude, Y. Niv, and A. Zemel

Phys. Rev. C 22, 97 (1980) - Published 1 July, 1980

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The $g$ factors of the $2_{1}^{+}$ states of even Sn nuclei have been measured using the dynamic magnetic field which acts on fast ions traversing thin magnetized iron foils. The results obtained are $g = + 0.37 \pm 0.13$ , $g ≳ 0$ , $g = - 0.16 \pm 0.10$ , $g = + 0.02 \pm 0.09$ , $g = - 0.14 \pm 0.07$ , $g = - 0.07 \pm 0.11$ , and $g = - 0.15 \pm 0.10$ for ${}^{112 - 124}{Sn}$ , respectively. The shell-model structure of the Sn isotopes is discussed.

NUCLEAR REACTIONS ${}^{112 - 124}{Sn}$ ( ${}^{35}{Cl}$ , ${}^{35}{Cl}$ ′) ${}^{112 - 124}{Sn}^{*}$ ( $2_{1}^{+}$ ) $E = 108$ MeV, enriched targets: measured $W (θ, H, \infty)$ ; fast ions in thin polarized iron. Deduced magnetic moments of the $2_{1}^{+}$ levels in ${}^{112 - 124}{Sn}$ .

Inelastic excitation of ${}^{12}C$ and ${}^{14}N$ by 122 MeV protons and implications for the effective nucleon-nucleon interaction

J. R. Comfort, Sam M. Austin, P. T. Debevec, G. L. Moake, R. W. Finlay, and W. G. Love

Phys. Rev. C 21, 2147 (1980) - Published 1 June, 1980

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Cross sections for the ${}^{12}C$ ( $p$ , $p^{'}$ ) ${}^{12}C$ and ${}^{14}N$ ( $p$ , $p^{'}$ ) ${}^{14}N$ reactions have been measured at $E_{p} = 122$ MeV. Scattered protons were momentum analyzed in a dispersion-matched magnetic spectrograph and detected in a helical-cathode position-sensitive proportional counter. Transitions to states in ${}^{12}C$ at 4.44 MeV ( $2^{+}$ , $T = 0$ ), 12.71 MeV ( $1^{+}$ ,0), 15.11 MeV ( $1^{+}$ ,1), 16.11 MeV ( $2^{+}$ ,1), and in ${}^{14}N$ at 2.31 MeV ( $0^{+}$ ,1) and 3.95 MeV ( $1^{+}$ ,0), are very useful for studying the spin-isospin dependence of the effective two-nucleon interaction. Cross sections for these states from the present experiment and from earlier measurements at 185 MeV have been analyzed in the distorted-wave impulse approximation. Simultaneous consideration of ( $e$ , $e^{'}$ ) data for the same transitions helped to disentangle some nuclear-structure and reaction-mechanism effects. The distorted-wave impulse approximation provides a good description of those transitions in ${}^{12}C$ mediated predominantly by the $S = T = 1$ part of the effective interaction and also gives a reasonable description of the $S = T = 0$ transitions in both nuclei. The mechanisms for excitation of the 12.71-MeV state in ${}^{12}C$ ( $S = 1$ , $T = 0$ ) and the 2.31-MeV state in ${}^{14}N$ ( $S = 1$ , $T = 1$ ) remain a puzzle.

NUCLEAR REACTIONS ${}^{12}C$ , ${}^{14}N$ ( $p$ , $p$ ), ( $p$ , $p^{'}$ ), $E = 122$ MeV; measured $σ (E_{p}, θ)$ ; resolution 100 keV; $θ = 6 - 60 °$ . ${}^{12}C$ $2^{+}$ states deduced $β_{2}$ DWIA analysis; microscopic effective interaction with $\vec{L} \cdot \vec{S}$ , tensor, and exchange terms.

Scattering and reaction dynamics for the ${}^{12}C$ + $p$ system

J. R. Comfort and B. C. Karp

Phys. Rev. C 21, 2162 (1980) - Published 1 June, 1980

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Elastic scattering data for proton scattering from ${}^{12}C$ are analyzed phenomenologically by use of local, complex, one-channel optical-model potentials and in an extended coupled-reaction-channel environment. Although the back-coupling amplitudes in the elastic channel from pickup-stripping paths through ${}^{11}C$ intermediate states are found to be quite sizable, the optical-model potential is able to simulate most of the effects quite well for both scattering and reaction processes at energies greater than about 60 MeV. The parameters of the optical-model potential and the residual optical-model potential of the coupled-reaction-channel environment are found to vary smoothly with energy. Below 60 MeV, these parameters have quite different trends and the ability of the one-channel optical-model potential to simulate the singular effects of strong couplings is much reduced.

NUCLEAR REACTIONS ${}^{12}C$ + $p$ system, energies up to 185 MeV; optical-model phenomenological analysis; coupled-reaction-channel analysis; comparison with DWBA calculations.

Electroexcitation of odd-parity states in ${}^{27}{Al}$

R. S. Hicks, A. Hotta, J. B. Flanz, and H. deVries

Phys. Rev. C 21, 2177 (1980) - Published 1 June, 1980

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Inelastic electron scattering form factors were measured for the low-lying odd-parity states of ${}^{27}{Al}$ over a momentum transfer range of 0.57 to 2.41 ${fm}^{- 1}$ . Reduced ground-state transition probabilities were deduced for states at $4.055 MeV (\frac{1}{2^{-}})$ , $5.156 MeV (\frac{3}{2^{-}})$ , $6.159 MeV (\frac{3}{2^{-}})$ , $6.477 MeV (\frac{7}{2^{-}})$ , $6.605 MeV (\frac{1}{2^{-}} or \frac{3}{2^{-}})$ , $6.651 MeV (\frac{5}{2^{-}})$ , $6.993 MeV (\frac{3}{2^{-}})$ , and $7.228 MeV (\frac{9}{2^{-}})$ . In addition, the results support odd-parity assignments for the $5.827 MeV (\frac{3}{2^{-}} or \frac{5}{2^{+}})$ and $7.477 MeV (\frac{7}{2})$ levels. Attempts have been made to interpret the results in terms of the weak-coupling and strong-coupling models. The measurements confirm the apparent high concentration of $1 p$ -shell proton hole strength in the 4.055 MeV, $\frac{1}{2^{-}}$ and 5.156 MeV, $\frac{3}{2^{-}}$ states. To satisfactorily account for the observed properties of these two levels using the weak-coupling model requires an anomalously small value of 1.35 MeV for the spin-orbit splitting of the $1 p$ shell. The structure of levels in the 6 to 7.5 MeV region is shown to be based on the excitation of $1 d$ -shell nucleons into the $1 f$ shell.

NUCLEAR REACTIONS ${}^{27}{Al}$ ( $e$ , $e^{'}$ ), $E = 70 - 340$ MeV; measured $σ (E; θ)$ , DWBA analysis. $π = - 1$ levels, deduced $B (Λ)$ , $δ$ . Strong-coupling model, weak-coupling model.

Neutron total cross section of sulfur: Single level to multilevel to optical model

C. H. Johnson and R. R. Winters

Phys. Rev. C 21, 2190 (1980) - Published 1 June, 1980

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This paper is a further analysis of the high resolution total cross section of sulfur for 25-1100 keV neutrons that previously were measured by Halperin, Johnson, Winters, and Macklin and evaluated by single-level analysis. The usual procedure in reporting the results of high resolution neutron cross sections has been to present the data and resonance parameters with corresponding neutron strength functions resulting from some type of $R$ -matrix analysis. Often the important nonresonant phase shifts are not reported. In this paper, making use of both strength functions and phase shifts, we extend the analysis to include an average nuclear potential (a spherical optical model). An optical model analysis not only facilitates comparison with a broad spectrum of other nucleon-nucleus experiments, but also may provide an incentive for microstructure calculations. Six average empirical functions, two each for $s_{\frac{1}{2}}$ , $p_{\frac{1}{2}}$ , and $p_{\frac{3}{2}}$ partial waves, are derived from the $R$ -matrix analysis. From these we deduce optical model parameters, the real and imaginary well depths for $s$ - and $p$ -wave neutrons, and the spin-orbit well depth for $p$ waves. The resulting real well is deeper for $p$ waves than for $s$ waves and for averages over partial waves at higher energies. The depth of the imaginary wells are about half those deduced at higher energies. An interesting feature of the analysis is that the multilevel curve including interference effects is produced from single-level parameters including the phase shifts.

NUCLEAR REACTIONS ${}^{32}S$ ( $n$ , $n$ ), $E_{n} = 25 - 1100$ keV, multilevel analysis of $σ_{n, tot} (E)$ , deduced $R^{'}$ , strength functions for $l = 0 and 1$ , optical model parameters for $l = 0 and 1$ .

Wave-function formalisms in the channel coupling array theory of many-body scattering

F. S. Levin

Phys. Rev. C 21, 2199 (1980) - Published 1 June, 1980

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Wave-function formalisms corresponding to different channel coupling array transition operators of many-body scattering theory are derived and discussed. The Kouri-Levin transition operators are seen to be in typical Lippmann-Schwinger form and allow for the introduction of wave-function components in a particularly straightforward way. The Baer-Kouri transition operators are not in the Lippmann-Schwinger form and an alternate procedure is used to derive their corresponding wave-function components. In the three-body case, the Kouri-Levin operators ${\hat{T}}_{jk}$ obtained from the Faddeev-Lovelace choice of channel coupling array are seen to lead to precisely the Faddeev wave-function components. The Bear-Kouri operators are shown to lead to wave-function components obeying inhomogeneous equations. These inhomogeneous equations are used to give an alternate explanation of the nonunitary amplitudes obtained in recent calculations based on approximate forms of the Baer-Kouri operators.

NUCLEAR REACTIONS Many-body scattering theory, channel coupling array wave-function formalisms, aspects of the bound-state type of approximation method, explanation of some nonunitary numerical results of Baer and Kouri and of Lewanski and Tobocman.

Proton-nucleus charge exchange measurements at 144 MeV as a test of one-pion exchange and the partially conserved axial vector current

G. L. Moake, L. J. Gutay, R. P. Scharenberg, P. T. Debevec, and P. A. Quin

Phys. Rev. C 21, 2211 (1980) - Published 1 June, 1980

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We have measured the differential cross sections of the ( $p$ , $n$ ) reaction of ${}^{6}{Li}$ , ${}^{12}C$ , and ${}^{14}N$ to the ground state of the final nucleus ( $Δ J = 1$ , $Δ T = 1$ , $Δ π = 0$ ) and to the 7.77 MeV excited state of ${}^{14}O$ at $E_{p} = 144$ MeV and $O ° < θ_{lab} < 20 °$ . For the ground state cases, we treat the nuclei as elementary particles, which are assigned the initial nucleus-pion-final nucleus coupling constants predicted using the partially conserved axial vector current. The Born helicity amplitudes for one-pion exchange are presented along with a method for including distortions in momentum space. The calculations which have no free parameters agree with the data for ${}^{6}{Li}$ and ${}^{12}C$ , but not for ${}^{14}N$ .

NUCLEAR REACTIONS ${}^{6}{Li}$ ( $p$ , $n$ ), ${}^{12}C$ ( $p$ , $n$ ), and ${}^{14}N$ ( $p$ , $n$ ) at $E_{p} = 144$ MeV. Differential cross sections measured between 0° and 20° (lab). Initial nucleus-pion-final nucleus coupling constants extracted.

Reaction ${}^{27}{Al}$ ( $α$ , $d$ ) ${}^{29}{Si}$ at 27.2 MeV

L. C. Bland, H. T. Fortune, O. K. Gorpinich, Yu S. Stryuk, V. N. Shcherbin, and V. V. Tokarevski

Phys. Rev. C 21, 2227 (1980) - Published 1 June, 1980

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At a bombarding energy of 27.2 MeV, complete angular distributions have been measured for the reaction ${}^{27}{Al}$ ( $α$ , $d$ ) ${}^{29}{Si}$ , populating the seven lowest states of ${}^{29}{Si}$ . Data have been analyzed in distorted-wave Born approximation, using both cluster and microscopic formalisms. For the latter, transfer amplitudes were taken from shell-model and weak-coupling calculations.

NUCLEAR REACTION ${}^{27}{Al}$ ( $α$ , $d$ ); $E = 27.2$ MeV; measured $σ (E_{d}, θ)$ , $θ = 3 - 169 °$ ${}^{29}{Si}$ levels. DWBA analysis, microscopic and macroscopic.

Finite range distorted-wave Born approximation analysis of ( $p$ , $t$ ) reactions with a realistic triton wave function

M. F. Werby, M. R. Strayer, and M. A. Nagarajan

Phys. Rev. C 21, 2235 (1980) - Published 1 June, 1980

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Exact finite range distorted-wave Born approximation analysis of the ground state reactions ${}^{208}{Pb}$ ( $p$ , $t$ ) ${}^{206}{Pb}$ and ${}^{18}O$ ( $p$ , $t$ ) ${}^{16}O$ are presented. The calculations are carried out using a realistic triton wave function comprising a spatially symmetric $S$ and mixed symmetric $S^{'}$ and $D$ states. The transfer interaction is treated consistently with the interaction used in obtaining the triton wave function. The use of a realistic wave function and transfer potential yields improved agreement between experimental and theoretical angular distributions. Calculations using the wave function of the transferred neutron pair suggest it is possible to explain both the absolute magnitude and shape of the angular distribution for these transitions.

NUCLEAR REACTIONS ( $p$ , $t$ ), distorted-wave Born approximation analyses.

${}^{210}{Bi}^{m} (d, t)$ reaction; ${}^{210}{Bi}$ ( $9^{-}$ ) parentage of states in ${}^{209}{Bi}$

T. P. Cleary, W. D. Callender, and R. K. Sheline

Phys. Rev. C 21, 2244 (1980) - Published 1 June, 1980

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Configuration assignments and spectroscopic factors are deduced from angular distribution data on 22 levels or level groupings in ${}^{209}{Bi}$ using the reaction ${}^{210}{Bi}^{m} (d, t) {}^{209}{Bi}$ at $E_{d} = 17$ MeV. Transitions to levels in ${}^{209}{Bi}$ between 2.6 and 6.0 MeV are observed and these levels are interpreted in terms of the coupling of the pure ${| h_{\frac{9}{2}}^{π}, g_{\frac{9}{2}}^{ν} |}_{9^{-}}$ target state with neutron holes in ${}^{207}{Pb}$ . The $j$ values of the transferred neutron are determined through comparison of the measured angular distributions and energies with angular distributions and energies for the corresponding single-hole states in ${}^{207}{Pb}$ . Levels below 5.0 MeV are assigned $p_{\frac{1}{2}}$ , $p_{\frac{3}{2}}$ , or $f_{\frac{5}{2}}$ neutron hole parentage while the levels above 5.0 MeV all have $f_{\frac{7}{2}}$ neutron hole parentage. The results complement and extend previous inelastic scattering and analog resonance studies on levels below 4.0 MeV excitation in ${}^{209}{Bi}$ . In particular, the summed spectroscopic strength for the $p_{\frac{1}{2}}$ neutron hole parentage states agrees well with the theoretical sum rule limit and measured single-hole strength in ${}^{207}{Pb}$ . The microscopic shell model (in contrast to the weak-coupling model) successfully predicts the observed splitting of spectroscopic strength among the members of the ( ${| h_{\frac{9}{2}}^{π}, g_{\frac{9}{2}}^{ν} |}_{9^{-}} \otimes p_{\frac{1}{2}}^{- 1 ν}$ ) multiplet.

NUCLEAR REACTIONS ${}^{210}{Bi}^{m} (d, t) {}^{209}{Bi}$ , $E_{d} = 17$ MeV. $θ_{lab} = 12.5 °, 20 °, 27.5 °, 35 °, 42.5 °, 50 °, 57.5 °, 72.5 °, 87.5 °, 100 °, 115 °$ . Measured $σ (θ)$ for $E^{*} ({}^{209}{Bi}) = 2700 - 6000$ keV. Deduced $l_{j}^{- 1 ν}$ , spectroscopic factors.

Global optical model potential for elastic deuteron scattering from 12 to 90 MeV

W. W. Daehnick, J. D. Childs, and Z. Vrcelj

Phys. Rev. C 21, 2253 (1980) - Published 1 June, 1980

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A set of about 4000 data points has been used in a global search for a general optical model parameter prescription. This potential for deuteron-nucleus scattering was confined to remain within the range given by folding model calculations. The data set spans the energy range from 11.8 to 90 MeV and includes many targets ranging in mass from ${}^{27}{Al}$ to ${}^{238}{Th}$ . The set includes 50 reaction cross sections, 13 angular distributions for vector polarization at and above 15 MeV, and 103 angular distributions for elastic scattering. A successful 11-parameter potential of the conventional form fits all data analyzed to about 18% rms. Two of these parameters, $V_{R}$ and $a_{I}$ , are functions of proton number and target mass, while five ( $V_{R}$ , $a_{o}$ , $W_{S}$ , $W_{D}$ , $V_{LS}$ ) are smooth functions of bombarding energy. The remainder ( $r_{o}$ , $r_{I}$ , $r_{c}$ , $r_{LS}$ , $a_{LS}$ ) are constants. A simple functional dependence for $a_{I} (A, Z)$ approximately reproduces the rapid changes in $σ (θ)$ found experimentally for nuclei at or near neutron shell closure. A comparison with earlier work suggests that the optical model analyses furnish the rms radii for the real and imaginary potentials with little ambiguity. General agreement but with a somewhat larger scatter (10%) is also found for the real and the imaginary volume integrals deduced. However, little consistency is seen for the imaginary volume integral if the bombarding energy is below 15 MeV. The rms radii and volume integrals have a small but distinct energy dependence. It was found that the 11-parameter potential occasionally has difficulty delivering good simultaneous fits for cross sections and vector polarizations. This situation was improved by the addition of a small, three-parameter imaginary spin-orbit term, which in our global prescription required short range and very small diffuseness.

NUCLEAR REACTIONS $A (d, d) A$ for $27 <~ A <~ 238$ , $11.8 <~ E <~ 90$ MeV. Optical model analysis. Deduced: global optical model parameter prescriptions, real and imaginary volume integrals, and rms radii.

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13.9 MeV neutron spin flip in ${}^{32}S$ $2^{+}$ (2.23 MeV) excitation

Nonstatistical structure in ${}^{12}C ({}^{14}N, α) {}^{22}{Na}$

Backward angle anomaly in inelastic alpha scattering from calcium isotopes

Analyzing power measurements for two-nucleon transfer reactions in a shape transitional nucleus

Evidence for nuclear shape coexistence at $N = 88$ : ${}^{152}{Eu} (d, p)$ and ( $d, t$ ) reactions

Properties of the 2p-1h intermediate structure in ${}^{41}{Sc}$

Reaction ${}^{3}{He} (γ, 2 p) n$ at intermediate photon energies

Angular distributions in a unified model of preequilibrium and equilibrium neutron emission

Radial sensitivity of elastic scattering

Magnetic moments of the $2_{1}^{+}$ levels in even Sn isotopes

Inelastic excitation of ${}^{12}C$ and ${}^{14}N$ by 122 MeV protons and implications for the effective nucleon-nucleon interaction

Scattering and reaction dynamics for the ${}^{12}C$ + $p$ system

Electroexcitation of odd-parity states in ${}^{27}{Al}$

Neutron total cross section of sulfur: Single level to multilevel to optical model

Wave-function formalisms in the channel coupling array theory of many-body scattering

Proton-nucleus charge exchange measurements at 144 MeV as a test of one-pion exchange and the partially conserved axial vector current

Reaction ${}^{27}{Al}$ ( $α$ , $d$ ) ${}^{29}{Si}$ at 27.2 MeV

Finite range distorted-wave Born approximation analysis of ( $p$ , $t$ ) reactions with a realistic triton wave function

${}^{210}{Bi}^{m} (d, t)$ reaction; ${}^{210}{Bi}$ ( $9^{-}$ ) parentage of states in ${}^{209}{Bi}$

Global optical model potential for elastic deuteron scattering from 12 to 90 MeV

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