Recent Articles

Spin excitations in ${}^{40}{Ca}$ (p,n)

T. N. Taddeucci, J. Rapaport, C. C. Foster, C. D. Goodman, C. Gaarde, J. Larsen, C. A. Goulding, D. J. Horen, T. Masterson, and E. Sugarbaker

Phys. Rev. C 28, 2511 (1983) - Published 1 December, 1983

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The ${}^{40}{Ca}$ (p,n) reaction at $E_{p} = 159.3$ MeV excites a state at $E_{x} = 2.7 \pm 0.1$ MeV in ${}^{40}{Sc}$ . The energy dependence and differential cross section angular distribution for this reaction indicate that this state is the $T_{z} = - 1$ analog of a known $1^{+}$ state at $E_{x} = 10.32$ MeV in ${}^{40}{Ca}$ . We find that the Gamow-Teller strength for this $0^{+}$ → $1^{+}$ (p,n) transition is $B (GT) = 0.21 \pm 0.04$ . Comparison of $B (GT)$ to $B (M 1) ↑$ for the analogous $M 1$ transition in ${}^{40}{Ca}$ indicates a substantial orbital-current contribution to the $M 1$ strength. The ${}^{40}{Ca}$ (p,n) reaction also strongly excites a $2^{-}$ state at $E_{x} = 0.77$ MeV in ${}^{40}{Sc}$ . Good agreement is found between properly normalized distorted-wave impulse approximation calculations and the measured differential cross sections for this transition at 159.3 MeV.

NUCLEAR REACTIONS ${}^{40}{Ca}$ (p,n) ${}^{40}{Sc}$ , $E_{p} = 59.3, 118.3, 159.3$ MeV, $E_{x} = 0.0, 0.77, 2.35, 2.7, 4.3$ MeV, measured $σ (θ)$ , $θ = 0 - 24 °$ , deduced $B (GT)$ for 2.7 MeV state. ${}^{42}{Ca}$ (p,n) ${}^{42}{Sc}$ (0.611 MeV), $E_{p} = 159.3$ MeV, measured $σ (θ)$ , $θ = 0 - 20 °$ .

Polarization effects in two-nucleon transfer reactions and time-reversal invariance

S. Roman, O. Karban, J. M. Barnwell, J. D. Brown, P. V. Drumm, P. M. Lewis, and J. M. Nelson

Phys. Rev. C 28, 2515 (1983) - Published 1 December, 1983

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Polarized ${}^{3}{He}$ particles have been used to initiate ( ${}^{3}{\vec{He}}$ , p) reactions on light nuclei. The results obtained have been compared with the available data for ( ${}^{3}{He}$ , $\vec{p}$ ) and the inverse ( $\vec{p}$ , ${}^{3}{He}$ ) reactions. It is suggested that the reactions proceed predominantly by a direct transfer mechanism and follow a simple reaction model which relates the polarization of the ( ${}^{3}{He}$ , $\vec{p}$ ) to the analyzing power of the ( ${}^{3}{\vec{He}}$ , p) reaction according to the $S$ transfer. If time-reversal invariance is applied, the present ( ${}^{3}{\vec{He}}$ , p) results for ${}^{7}{Li}$ and ${}^{9}{Be}$ are in agreement with the ( $\vec{p}$ , ${}^{3}{He}$ ) measurements on ${}^{9}{Be}$ and ${}^{11}B$ targets.

NUCLEAR REACTIONS ${}^{7}{Li} ({}^{3}{\vec{He}}, p) {}^{9}{Be}$ , ${}^{9}{Be} ({}^{3}{\vec{He}}, p) {}^{11}B$ ; $E = 14$ MeV; ${}^{12}C ({}^{3}{\vec{He}}, p) {}^{14}N$ , $E = 33$ MeV; measured $A_{y} (θ)$ .

Target fragment angular distributions for the interaction of 25.2 GeV ${}^{12}C$ with ${}^{197}{Au}$

Y. Morita, W. Loveland, and G. T. Seaborg

Phys. Rev. C 28, 2519 (1983) - Published 1 December, 1983

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The target fragment angular distributions for the interaction of 25.2 GeV ${}^{12}C$ with ${}^{197}{Au}$ were measured. The data are generally in agreement with predictions based on the two step model and thick target-thick catcher recoil data.

NUCLEAR REACTIONS $Au ({}^{12}C, x)$ , $E_{{}^{12}C} = 25.2$ GeV, $σ (θ)$ , comparison of data with two step model, firestreak model.

Nuclear structure of ${}^{195}{Pt}$ and the multi- $j$ supersymmetry scheme

A. R. Ghatak-Roy and S. W. Yates

Phys. Rev. C 28, 2521 (1983) - Published 1 December, 1983

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Low-lying levels of ${}^{195}{Pt}$ have been studied by the (n, $n^{'} γ$ ) reaction at incident neutron energies from 0.5 to 2.0 MeV. Excitation function measurements have been used to confirm most previous level placements, and spin-parity assignments are elucidated by $γ$ -ray angular distributions. The results support previous arguments in favor of a multi- $j$ supersymmetry representation of the negative-parity states of ${}^{195}{Pt}$ .

NUCLEAR REACTIONS ${}^{195}{Pt} (n, n^{'} γ)$ , $E_{n} = 0.5 - 2.0$ MeV; measured $E_{γ}$ , $I_{γ}$ , $σ (E, E_{γ}, Θ_{γ)}$ ; ${}^{195}{Pt}$ deduced levels, $J$ , $π$ . Ge(Li) detector, enriched target. Comparison with predictions of multi- $j$ supersymmetry in interacting boson-fermion approximation.

Alpha-alpha potential

Luis Marquez

Phys. Rev. C 28, 2525 (1983) - Published 1 December, 1983

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The alpha-alpha interaction is described by a two body potential. It is shown that there is a two body potential of the Woods-Saxon form which gives correctly the energy and the decay width of the ${}^{8}{Be}$ ground state and also the phase shifts for $L = 0, 2, 4, and 6$ . The wave function representing the alpha particles in the ${}^{8}{Be}$ ground state has radial quantum number equal to three.

NUCLEAR REACTIONS ${}^{4}{He} (α, α) {}^{4}{He}$ , $E_{c . m .} = 0.2 to 15$ MeV. Computation of decay and scattering parameters and comparison with experimental values.

Spin-flip strength in the 20-28 MeV region of excitation in ${}^{12}C$ and the extended coupled-channels model predictions

S. Ramavataram

Phys. Rev. C 28, 2528 (1983) - Published 1 December, 1983

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The spin-flip strength distribution in the 20 to 28 MeV excitation in ${}^{12}C$ deduced from a recent study of the ${}^{12}C (π^{\pm}, {π^{\pm}}^{'})$ reaction is discussed in the context of an earlier coupled-channel analysis of the ${}^{11}B (p, γ_{1})$ reaction data. It is shown that a good correspondence can be established between certain broad resonances observed in the two types of reactions not only with regard to the energy but also the width. Definitive spin, isospin, and parity assignments can be made on the basis of this comparison.

NUCLEAR STRUCTURE ${}^{12}C$ ; analyzed reaction data; deduced spin-flip resonances, $J$ , $π$ , $T$ . Coupled-channels, DWIA models.

Imaginary part of the Coulomb correction in nucleon scattering from ${}^{28}{Si}$

R. P. DeVito, Sam M. Austin, U. E. P. Berg, R. De Leo, and W. A. Sterrenburg

Phys. Rev. C 28, 2530 (1983) - Published 1 December, 1983

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Cross sections for elastic scattering of neutrons from ${}^{28}{Si}$ have been measured at 30.3 and 40.0 MeV. Phenomenological values of the Coulomb correction term in the nucleon-nucleus optical-model potential are obtained from a comparison of proton and neutron elastic scattering data for ${}^{28}{Si}$ between 14 and 40 MeV. For energies less than about 28 MeV the result is similar to that obtained from an analysis of ${}^{40}{Ca}$ data. For higher energies the imaginary Coulomb correction is substantially larger for ${}^{28}{Si}$ than for ${}^{40}{Ca}$ .

NUCLEAR REACTIONS ${}^{28}{Si}$ (p,p), (n,n), $E = 14 - 40$ MeV; deduced optical-model parameters.

Complex heavy ion optical potential and the proximity concept

R. Sartor and Fl. Stancu

Phys. Rev. C 28, 2533 (1983) - Published 1 December, 1983

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We show that within the proximity frame and for low bombarding energies, one can construct a complex universal function giving access to both the real and imaginary volume contributions to the heavy ion optical potential.

NUCLEAR REACTIONS Complex heavy ion optical potential, proximity approximation.

Riemannian corrections to velocity-dependent nuclear forces

Lester Ingber

Phys. Rev. C 28, 2536 (1983) - Published 1 December, 1983

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It is argued that there is a measurable difference between the two-nucleon potential in the Schrödinger wave function and in the potential defined via meson exchanges, when relativistic effects are incorporated as velocity-dependent contributions. This necessitates a reformulation of the usual scattering, deuteron, and nuclear matter calculations.

NUCLEAR STRUCTURE Nuclear matter requires modified velocity-dependent potential. Nuclear forces, momentum dependence induces Riemannian corrections.

$J^{π} = 4^{+}$ level at 24.6 MeV excitation energy in ${}^{4}{He}$

J. J. Bevelacqua

Phys. Rev. C 28, 2540 (1983) - Published 1 December, 1983

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Dynamical $R$ -matrix methodology of Lane and Robson is used to determine the properties of the recently proposed $J^{π} = 4^{+}$ , $Γ \approx several$ MeV, $T = 0$ state at 24.6 MeV excitation energy in the ${}^{4}{He}$ system. The calculations lead to a $J^{π} = 4^{+}$ state with the following properties: $E_{x} = 42.4$ MeV, $T = 0$ , and $Γ = 4.0$ MeV. The model results and data are in reasonable agreement except for predictions of the excitation energy of the $4^{+}$ level. Discrepancies in the excitation energy may be due to model space truncation restrictions, model interaction inadequacies, or uncertainties in the experimental location of the ( $4^{+}$ ,0) level.

NUCLEAR STRUCTURE Calculated via dynamical $R$ -matrix methodology the following properties for the proposed ( $4^{+}$ ,0) resonance of Grüebler et al. in ${}^{4}{He}$ : $J^{π} = 4^{+}$ , $T = 0$ , $Γ = 4.0$ MeV, and $E_{x} = 42.4$ MeV.

Semiphenomenological method of analysis for intermediate-energy alpha-nucleus elastic scattering data

I. Ahmad and M. A. Alvi

Phys. Rev. C 28, 2543 (1983) - Published 1 December, 1983

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We propose a semiphenomenological method of analysis for intermediate energy $α$ -nucleus elastic scattering experiments and demonstrate its usefulness by analyzing available elastic $α$ -nucleus scattering data at 1.37 GeV.

NUCLEAR REACTIONS Proposed effective N- $α$ amplitude, analyzed ${}^{40, 42, 44, 48}{Ca}$ , ${}^{12}C (α, α)$ , $E = 1.37$ GeV; Glauber model. Sole free parameter target independent.

Erratum: Effective two-nucleon potential for high-energy heavy-ion collisions

G. S. Anagnostatos and C. N. Panos

Phys. Rev. C 28, 2546 (1983) - Published 1 December, 1983

Erratum: Inelastic excitation and spin flip in heavy ion reactions

S. Chakravarti, P. J. Ellis, B. F. Bayman, and Q. K. K. Liu

Phys. Rev. C 28, 2546 (1983) - Published 1 December, 1983

Erratum: Inelastic proton scattering to particle-hole states in ${}^{40}{Ca}$ and spin-isospin excitation of pion symmetry states

H. Ejiri, M. Sasao, T. Shibata, H. Ohsumi, Y. Fujita, M. Fujiwara, T. Yamazaki, I. Katayama, S. Morinobu, and H. Ikegami

Phys. Rev. C 28, 2546 (1983) - Published 1 December, 1983

Erratum: Implications of angular momentum conservation for fluctuations in heavy ion reactions

L. C. Dennis

Phys. Rev. C 28, 2547 (1983) - Published 1 December, 1983

Erratum: Lee model field theory of three-nucleon system

M. Sawicki

Phys. Rev. C 28, 2547 (1983) - Published 1 December, 1983

RAPID COMMUNICATION

True absorption and scattering of 50 MeV pions

I. Navon, D. Ashery, J. Alster, G. Azuelos, B. M. Barnett, W. Gyles, R. R. Johnson, D. R. Gill, and T. G. Masterson

Phys. Rev. C 28, 2548(R) (1983) - Published 1 December, 1983

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The inclusive pion inelastic scattering and true absorption cross sections at 50 MeV were measured for $π^{+}$ on natural Li, C, Fe, Nb, and Bi and for $π^{-}$ on C, Fe, and Bi. The results show that $π^{-}$ cross sections are much larger than $π^{+}$ , the difference being significantly larger than expected from a simple Coulomb calculation. In particular, in ${}^{12}C$ the absorption of negative pions is about twice that of positive pions.

NUCLEAR REACTIONS Li, C, Fe, Nb, Bi ( $π^{+}, {π^{+}}^{'}$ ) and C, Fe, Bi ( $π^{-}, {π^{-}}^{'}$ ), $E_{π} = 50$ MeV; measured $σ (θ_{π^{'}})$ , transmission; deduced $σ_{absorption}$ .

RAPID COMMUNICATION

Analyzing power of the $\vec{p} p \to π^{+} d$ reaction at 375, 450, and 500 MeV incident proton energies

G. L. Giles, E. G. Auld, G. Jones, G. J. Lolos, B. J. McParland, W. Ziegler, D. Ottewell, P. Walden, and W. R. Falk

Phys. Rev. C 28, 2551(R) (1983) - Published 1 December, 1983

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The analyzing power $A_{N 0}$ of the $\vec{p} p \to π^{+} d$ reaction was measured to a statistical precision of better than ±0.01 at incident proton beam energies of 375, 450, and 500 MeV, for center-of-mass angles from 20° to 150°. The polarization-dependent differential cross sections were fitted by associated Legendre functions (using published data for the shapes of the unpolarized differential cross sections). The energy dependence of the resulting $b_{k}^{N 0}$ coefficients were compared with existing data and theoretical expectations.

NUCLEAR REACTIONS $\vec{p} p \to π^{+} d$ ; polarized protons; $E = 375, 450, 500$ MeV; measured $A_{N 0} (E, θ)$ ; $θ = 20 - 150 °$ c.m.; deduced $b_{1}^{N 0} (E) - b_{5}^{N 0} (E)$ .

RAPID COMMUNICATION

Giant dipole resonance in the statistical decay of ${}^{63}{Cu}$ , ${}^{76}{Kr}$ , and ${}^{127}{Cs}$ compound nuclei

E. F. Garman, K. A. Snover, S. H. Chew, S. K. B. Hesmondhalgh, W. N. Catford, and P. M. Walker

Phys. Rev. C 28, 2554(R) (1983) - Published 1 December, 1983

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The spectral shapes of high energy gamma rays emitted in the decay of excited ${}^{63}{Cu}$ , ${}^{76}{Kr}$ , and ${}^{127}{Cs}$ compound nuclei are well reproduced by statistical model calculations which include a giant dipole resonance 1-1.5 MeV lower in energy than the ground-state giant dipole resonance. No evidence is found for a dependence of the giant dipole resonance strength function on spin.

NUCLEAR REACTIONS ${}^{12}C$ + ${}^{51}V$ , ${}^{64}{Zn}$ , ${}^{115}{In}$ ; ${}^{18}O$ + ${}^{45}{Sc}$ , ${}^{58}{Ni}$ , ${}^{109}{Ag}$ ; $E_{lab} = 42 - 60$ MeV. Measured $γ$ -ray spectra, $E_{γ} = 6 - 25$ MeV; compared with statistical model calculations including the GDR. Deduced $E_{GDR}$ , $γ$ for excited state GDR decays. Deduced upper limits for spin dependence of GDR parameters.

RAPID COMMUNICATION

Search for rapid angular and energy dependence of $\frac{d σ}{d Ω}$ and $i T_{11}$ in large angle $π$ -d elastic scattering

E. L. Mathie, G. R. Smith, E. T. Boschitz, M. Meyer, F. Vogler, M. Daum, S. Mango, and J. A. Konter

Phys. Rev. C 28, 2558(R) (1983) - Published 1 December, 1983

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Spin excitations in ${}^{40}{Ca}$ (p,n)

Polarization effects in two-nucleon transfer reactions and time-reversal invariance

Target fragment angular distributions for the interaction of 25.2 GeV ${}^{12}C$ with ${}^{197}{Au}$

Nuclear structure of ${}^{195}{Pt}$ and the multi- $j$ supersymmetry scheme

Alpha-alpha potential

Spin-flip strength in the 20-28 MeV region of excitation in ${}^{12}C$ and the extended coupled-channels model predictions

Imaginary part of the Coulomb correction in nucleon scattering from ${}^{28}{Si}$

Complex heavy ion optical potential and the proximity concept

Riemannian corrections to velocity-dependent nuclear forces

$J^{π} = 4^{+}$ level at 24.6 MeV excitation energy in ${}^{4}{He}$

Semiphenomenological method of analysis for intermediate-energy alpha-nucleus elastic scattering data

Erratum: Effective two-nucleon potential for high-energy heavy-ion collisions

Erratum: Inelastic excitation and spin flip in heavy ion reactions

Erratum: Inelastic proton scattering to particle-hole states in ${}^{40}{Ca}$ and spin-isospin excitation of pion symmetry states

Erratum: Implications of angular momentum conservation for fluctuations in heavy ion reactions

Erratum: Lee model field theory of three-nucleon system

True absorption and scattering of 50 MeV pions

Analyzing power of the $\vec{p} p \to π^{+} d$ reaction at 375, 450, and 500 MeV incident proton energies

Giant dipole resonance in the statistical decay of ${}^{63}{Cu}$ , ${}^{76}{Kr}$ , and ${}^{127}{Cs}$ compound nuclei

Search for rapid angular and energy dependence of $\frac{d σ}{d Ω}$ and $i T_{11}$ in large angle $π$ -d elastic scattering

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