Recent Articles

Effective interactions in self-consistent nuclear many-body calculations using the Green's functions technique

V. Klemt, S. A. Moszkowski, and J. Speth

Phys. Rev. C 14, 302 (1976) - Published 1 July, 1976

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In this paper we discuss the connection and differences between effective particle-particle and particle-hole interactions using the Green's function method. We also consider the relation between the Skyrme and Landau-Migdal effective internucleon interactions for nucleons on top of the Fermi sea in infinite nuclear matter.

NUCLEAR STRUCTURE Definition of different residual interactions in many-body calculations. Comparison of Skyrme and Landau-Migdal force.

Quasiparticle interaction in nuclear matter and the importance of contributions from low momentum states

R. S. Poggioli and A. D. Jackson

Phys. Rev. C 14, 311 (1976) - Published 1 July, 1976

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A microscopic calculation of the quasiparticle interaction in nuclear matter is detailed. In order to take special care of the contributions from the low momentum states, a model space is introduced. Excluded from the model space, the high momentum states are absorbed into the model interaction. Brueckner-Bethe theory suggests the choice of a truncated $G$ matrix as a good approximation for this model interaction. A simple perturbative approach is attempted within the model space. The calculated quasiparticle interaction is consistent with experimental results.

NUCLEAR STRUCTURE Nuclear matter quasiparticle interaction evaluated. Crucial role of low momentum states (associated with important long-range correlations) discussed.

RAPID COMMUNICATION

$g$ factor of the 879 keV state of ${}^{70}{Ga}$

T. Taylor and D. A. Hutcheon

Phys. Rev. C 14, 329(R) (1976) - Published 1 July, 1976

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The $g$ factor of the 879 keV state of ${}^{70}{Ga}$ has been measured by the time differential perturbed angular distribution method. The reaction ${}^{69}{Ga} (d, p) {}^{70}{Ga}$ on a target of liquid gallium was used to populate the state in a magnetic flux density of 20 kG. The anomalously small empirical result $g = - 0.066 \pm 0.025$ can be explained in terms of configuration mixing.

NUCLEAR REACTIONS ${}^{69}{Ga} (d, p)$ , $E = 5$ MeV; measured $γ (θ, B, t)$ , $B = 20$ kG; deduced $g$ (879 keV).

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Structure of the ${}^{12}C$ + ${}^{12}C$ resonances

J. Castro and P. Federman

Phys. Rev. C 14, 332(R) (1976) - Published 1 July, 1976

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It is shown that the resonances in the ${}^{12}C$ + ${}^{12}C$ system near and below the Coulomb barrier can be understood in the framework of the quasimolecular model. The model accounts for all the observed resonances without introducing new degrees of freedom.

[NUCLEAR STRUCTURE ${}^{12}C$ + ${}^{12}C$ resonances calculated, $J$ , $π$ . Quasimolecular model.]

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Two-body final-state coincidence measurements for fissionlike processes following ${}^{35}{Cl}$ + ${}^{27}{Al}$ fusion

T. M. Cormier, E. R. Cosman, A. J. Lazzarini, J. D. Garrett, and H. E. Wegner

Phys. Rev. C 14, 334(R) (1976) - Published 1 July, 1976

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A two-body final state with a mass distribution centered about half the mass of the compound system and with an average kinetic energy distribution equal to the Coulomb energy of the final system is observed following the fusion of ${}^{35}{Cl}$ with ${}^{27}{Al}$ at 170 MeV incident energy. Such a process is consistent with the onset of a fissionlike process resulting from the lowering of the rotating liquid drop fission barrier as a function of angular momentum.

NUCLEAR REACTIONS, FISSION ${}^{35}{Cl}$ + ${}^{27}{Al}$ fusion, $E = 170$ MeV; measured fragment-fragment ( $E$ ; $A$ ).

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Giant dipole resonance in ${}^{56}{Fe}$ observed via ( $p, γ$ ) and ( $α, γ$ ) reactions

D. G. Rickel, C. P. Cameron, R. D. Ledford, N. R. Roberson, H. R. Weller, and D. R. Tilley

Phys. Rev. C 14, 338(R) (1976) - Published 1 July, 1976

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A comparison is made between the yield curves of the measured ${}^{52}{Cr} (α, γ_{0})$ and ${}^{55}{Mn} (p, γ_{0})$ reactions in the giant dipole resonance region of ${}^{56}{Fe}$ ( $E_{x} = 14.0 to 21.5$ MeV) to determine if the gross differences can be interpreted as being due to isospin effects. Above 18 MeV the yield of ( $γ, α_{0}$ ), determined by the principle of detailed balance, is observed to drop below the value obtained when the energy dependence of the transmission coefficients is removed. This leads to the conclusion that while the diminished yield in the ( $γ, α_{0}$ ) channel may be due to the failure to populate the isospin forbidden $T_{>}$ states, other effects cannot be ruled out.

NUCLEAR REACTIONS ${}^{52}{Cr} (α, γ_{0})$ , $E_{α} = 7.0 - 14.0$ MeV, ${}^{55}{Mn} (p, γ_{0})$ , $E_{p} = 4.0 - 11.7$ MeV, measured $σ (E_{x})$ , Isospin splitting of giant dipole resonance investigated.

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Large-amplitude collective motion in the Lipkin model

E. R. Marshalek

Phys. Rev. C 14, 342(R) (1976) - Published 1 July, 1976

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It is shown how a simple reinterpretation of the "transition-operator boson method" eliminates the difficulty noted by Okubo. The revised method is applied to the problem of anharmonic motion in the Lipkin model. The occurrence of a non-positive-definite mass parameter, as obtained by Holzwarth and by Giraud and Grammaticos, is then exposed as the easily avoidable consequence of an inauspicious choice of collective coordinate.

NUCLEAR STRUCTURE Approximate many-body method applied to a solvable model.

RAPID COMMUNICATION

Identification of 2.90-min ${}^{107}{Sn}$ and 50-sec ${}^{107}{In}^{m}$

H. -C. Hseuh and E. S. Macias

Phys. Rev. C 14, 345(R) (1976) - Published 1 July, 1976

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RAPID COMMUNICATION

Parity violation in the two nucleon system

John Missimer

Phys. Rev. C 14, 347(R) (1976) - Published 1 July, 1976

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The parity violating polarization asymmetries of nucleon-nucleon scattering at energies below 20 MeV are subject to a model-independent analysis. I discuss the asymmetries necessary to determine completely the weak interaction parameters and relate them to the parity violating observables in the thermal capture of neutrons. One of the relations provides a check of the photon asymmetry, the observable most sensitive to models of nonleptonic weak interactions.

NUCLEAR REACTIONS Deduce relations among nucleon-nucleon polarization asymmetries to determine parity violating amplitudes.

RAPID COMMUNICATION

${}^{142}{Nd}$ ( ${}^{18}O$ , ${}^{16}O$ ) ${}^{144}{Nd}$ reaction and its contrast to ${}^{144}{Nd}$ ( ${}^{12}C$ , ${}^{14}C$ ) ${}^{142}{Nd}$ reaction

K. Yagi, D. L. Hendrie, U. Jahnke, C. F. Maguire, J. Mahoney, D. K. Scott, D. H. Feng, T. Udagawa, K. S. Low, and T. Tamura

Phys. Rev. C 14, 351(R) (1976) - Published 1 July, 1976

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An investigation is made of the ${}^{142}{Nd}$ ( ${}^{18}O$ , ${}^{16}O$ ) ${}^{144}{Nd}$ reaction, in which it was found that the first excited $2^{+}$ state was populated strongly with an angular distribution characteristic of one-step transfer. This is in contrast to an earlier result for the inverse-type reaction ${}^{144}{Nd}$ ( ${}^{12}C$ , ${}^{14}C$ ) ${}^{142}{Nd}$ , in which the first excited state was found to be populated dominantly by a two-step process and to have an anomalous angular distribution.

NUCLEAR REACTIONS ${}^{142}N$ ( ${}^{18}O$ , ${}^{16}O$ ), $E = 98$ MeV; measured $σ (θ)$ , DWBA analysis.

RAPID COMMUNICATION

Projection operator treatment of single-particle resonances

Amos Lev and William P. Beres

Phys. Rev. C 14, 354(R) (1976) - Published 1 July, 1976

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A projection operator method is used to obtain the energy and width of a single-particle resonance. The resonance energy is found without scanning. An example of the first $g_{\frac{9}{2}}$ neutron resonance in ${}^{40}{Ca}$ is given and compared with the traditional phase shift method. The results of both approaches are quite similar.

NUCLEAR REACTIONS Single-particle resonances; calculated $E_{R}$ and $Γ$ . Projection operators; no scanning. Comparison with other methods.

RAPID COMMUNICATION

${}^{10}B ({}^{10}B, α) {}^{16}O$ reaction

F. Ajzenberg-Selove, R. R. Betts, and D. J. Crozier

Phys. Rev. C 14, 357(R) (1976) - Published 1 July, 1976

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The ${}^{10}B ({}^{10}B, α) {}^{16}O$ reaction has been investigated using a 20-MeV ${}^{10}B$ beam and a multiangle spectrograph. Twenty-nine $α$ groups have been observed corresponding to ${}^{16}O$ states with $E_{x} < 24$ MeV. The reaction excites known $T = 0$ states: $σ_{t}$ follow $2 J_{f} + 1$ for 11 of 12 groups. The angular distributions show little structure.

[NUCLEAR REACTIONS ${}^{10}B ({}^{10}B, α)$ , $E = 20$ MeV; measured $σ (θ)$ ${}^{10}O$ deduced levels.]

RAPID COMMUNICATION

Effects of the ( $π, N$ ) reaction on $π$ -nuclear elastic scattering

Gerald A. Miller

Phys. Rev. C 14, 361(R) (1976) - Published 1 July, 1976

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The ( $π, N$ ) reaction, in which a meson deposits its total energy on a single nucleon, is examined for its effect on $π$ -nuclear scattering. At energies from 30 to 75 MeV the reaction cross section is enhanced by about 10%, and the angular distributions are essentially unchanged. At higher energies the effects are smaller.

NUCLEAR REACTIONS ${}^{16}O (π, π)$ , ${}^{48}{Ca} (π, π)$ , $E = 50 - 250$ MeV. Pion-nucleus scattering. Theoretical optical potential. Meson annihilation reactions.

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Axial symmetry of ${}^{24}{Mg}$ and ${}^{32}S$ in the BCS approximation

P. Mpanias and M. L. Rustgi

Phys. Rev. C 14, 365(R) (1976) - Published 1 July, 1976

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Employing the modified Yale and supersoft core potentials, BCS calculations are carried out for the ground-state properties of ${}^{24}{Mg}$ and ${}^{32}S$ . It is found that the $T = 0$ neutron-proton pairing correlations under the axially symmetric shape are more energetically favorable for ${}^{32}S$ , and equally favorable for ${}^{24}{Mg}$ , than the asymmetric shape obtained through the Hartree-Fock procedure. Comparisons are made with BCS results obtained via the Yale potential using the same shell-model expansion basis.

NUCLEAR STRUCTURE ${}^{24}{Mg}$ , ${}^{32}S$ ; BCS method. Modified Yale and supersoft core interactions.

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High-lying low-spin cluster states in ${}^{15}N$

L. H. Harwood and K. W. Kemper

Phys. Rev. C 14, 368(R) (1976) - Published 1 July, 1976

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States in ${}^{15}N$ have been studied by comparing the ${}^{12}C ({}^{7}{Li}, α) {}^{15}N$ and ${}^{13}C ({}^{6}{Li}, α) {}^{15}N$ reactions. States assumed to have an ${(s d)}^{3}$ configuration because they are observed strongly in three particle transfer but not in two particle transfer are at 10.70, 12.57, 13.20, and 15.43 MeV, with the 12.57 and 13.20 having the lowest spins. The state previously assigned as ${(p_{\frac{1}{2}} \otimes d_{\frac{5}{2}}^{2})}_{\frac{11}{2} -}$ is found at 13.02 MeV in ${}^{15}N$ , in agreement with the previous result of 13.03 MeV.

NUCLEAR REACTIONS ${}^{13}C ({}^{6}{Li}, α)$ spectra, $E = 32$ MeV. ${}^{12}C ({}^{7}{Li}, α)$ spectra, $E = 34.9$ MeV; inferred structure of ${}^{15}N$ states by comparison of reactions.

Some results on the off-shell Jost function

Michael G. Fuda

Phys. Rev. C 14, 37 (1976) - Published 1 July, 1976

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A momentum space formulation of the off-shell Jost function is developed, and two new integral representations are derived for it. One representation relates the off-shell Jost function to a function that arises in Kowalski's generalized Sasakawa method; the other relates it to the regular solution of the Schrödinger equation.

NUCLEAR REACTIONS Momentum space formulation of off-shell Jost function, and integral representations for it.

RAPID COMMUNICATION

Resonating-group study of $n + {}^{40}{Ca}$ scattering

D. R. Thompson and Y. C. Tang

Phys. Rev. C 14, 372(R) (1976) - Published 1 July, 1976

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The scattering of neutrons by ${}^{40}{Ca}$ is studied with the resonating-group method and a generator-coordinate technique. The result for the differential cross section calculated at 13.76 MeV agrees quite well with experiment. Also, the calculation shows that the heavy-particle pickup process becomes less important in nucleon-nucleus scattering as the target mass increases.

[NUCLEAR REACTIONS ${}^{40}{Ca} (n, n)$ ; calculated phase shifts and $σ (θ)$ . Resonating-group method with generator-coordinate technique.

RAPID COMMUNICATION

Measurement of the magnetic dipole moment of $β$ -emitting ${}^{25}{Al}$ by use of a polarized proton beam and nuclear magnetic resonance detection

T. Minamisono, J. W. Hugg, J. R. Hall, D. G. Mavis, H. F. Glavish, and S. S. Hanna

Phys. Rev. C 14, 376(R) (1976) - Published 1 July, 1976

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Polarized $β$ -emitting ${}^{25}{Al}$ nuclei ( $I^{π} = {\frac{5}{2}}^{+}$ , $T_{\frac{1}{2}} = 7.2$ sec) were produced in the reaction ${}^{28}{Si} {(\vec{p}, α)}^{25} Al$ in a thick single crystal of Si which served as host for the implanted ${}^{25}{Al}$ nuclei. The net polarization transferred to the ${}^{25}{Al}$ nuclei was detected by measuring the asymmetry in the $β$ -decay. The magnetic dipole moment of ${}^{25}{Al}$ was measured by nuclear magnetic resonance destruction of the polarization. Including the diamagnetic correction, we obtain $μ = [3.6455 (12)] μ_{N}$ .

RADIOACTIVITY Polarized ${}^{25}{Al}$ from ${}^{28}{Si} (\vec{p}, α)$ ; measured $β$ asymmetry, polarization transfer, relaxation time $T_{1}$ , NMR; ${}^{25}{Al}$ deduced magnetic moment $μ$ . Natural thick target, magnetic fields, plastic scintillators.

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High-spin positive-parity levels in ${}^{41}{Ca}$

P. R. Goode and R. N. Boyd

Phys. Rev. C 14, 379(R) (1976) - Published 1 July, 1976

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The results of the ${}^{39}K (α, d) {}^{41}{Ca} (j^{+})$ , ${}^{41}{Ca} (α, α^{'}) {}^{41}{Ca} (j^{+})$ , and ${}^{40}K ({}^{3}{He}, d) {}^{41}{Ca} (j^{+})$ experiments are interpreted in simple shell model terms. The resulting wave functions are shown to give good reproductions of the results of the above reactions populating the ${17 / 2}^{+}$ , ${15 / 2}^{+}$ , ${13 / 2}^{+}$ , and ${11 / 2}^{+}$ levels in ${}^{41}{Ca}$ .

NUCLEAR STRUCTURE ${}^{41}{Ca}$ , $j^{π} = {\frac{11}{2}}^{+} - {\frac{17}{2}}^{+}$ ; calculated ${}^{39}K (α, d)$ , ${}^{41}{Ca} (α, α^{'})$ , and ${}^{40}K ({}^{3}{He}, d)$ strengths. Assumed two-particle-one-hole states.

Levels in ${}^{28}{Si}$ via the ${}^{26}{Mg} ({}^{3}{He}, n)$ reaction

R. N. Boyd, D. Elmore, W. P. Alford, J. P. Draayer, and R. A. Lindgren

Phys. Rev. C 14, 4 (1976) - Published 1 July, 1976

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The ${}^{26}{Mg} ({}^{3}{He}, n) {}^{28}{Si}$ reaction at $E_{{}^{3}{He}} = 15$ MeV has been studied. Relative strengths to excited states in ${}^{28}{Si}$ are determined from a distorted-wave Born-approximation analysis of the data. The ratios $\frac{S (0^{+} \to J^{π})}{S (0^{+} \to 0^{+})}$ for the lowest $J^{π} = 2^{+}, 4^{+}$ states compare favorably with predictions based on pure ${SU}_{3}$ symmetry. When compared with results from the ${}^{24}{Mg} ({}^{6}{Li}, d) {}^{28}{Si}$ a consistent picture for the structure of the 0.0 ( $0^{+}$ ), 1.78 ( $2^{+}$ ), 4.62 ( $4^{+}$ ), 4.98 ( $0^{+}$ ), and 6.69 ( $0^{+}$ ) MeV levels in ${}^{28}{Si}$ is suggested.

NUCLEAR REACTIONS ${}^{26}{Mg} ({}^{3}{He}, n) E = 15$ MeV; measured $σ (θ)$ , $θ_{lab} = 0 ° - 55 °$ ; extracted strength with DWBA, compared with ${SU}_{3}$ predictions.

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Effective interactions in self-consistent nuclear many-body calculations using the Green's functions technique

Quasiparticle interaction in nuclear matter and the importance of contributions from low momentum states

$g$ factor of the 879 keV state of ${}^{70}{Ga}$

Structure of the ${}^{12}C$ + ${}^{12}C$ resonances

Two-body final-state coincidence measurements for fissionlike processes following ${}^{35}{Cl}$ + ${}^{27}{Al}$ fusion

Giant dipole resonance in ${}^{56}{Fe}$ observed via ( $p, γ$ ) and ( $α, γ$ ) reactions

Large-amplitude collective motion in the Lipkin model

Identification of 2.90-min ${}^{107}{Sn}$ and 50-sec ${}^{107}{In}^{m}$

Parity violation in the two nucleon system

${}^{142}{Nd}$ ( ${}^{18}O$ , ${}^{16}O$ ) ${}^{144}{Nd}$ reaction and its contrast to ${}^{144}{Nd}$ ( ${}^{12}C$ , ${}^{14}C$ ) ${}^{142}{Nd}$ reaction

Projection operator treatment of single-particle resonances

${}^{10}B ({}^{10}B, α) {}^{16}O$ reaction

Effects of the ( $π, N$ ) reaction on $π$ -nuclear elastic scattering

Axial symmetry of ${}^{24}{Mg}$ and ${}^{32}S$ in the BCS approximation

High-lying low-spin cluster states in ${}^{15}N$

Some results on the off-shell Jost function

Resonating-group study of $n + {}^{40}{Ca}$ scattering

Measurement of the magnetic dipole moment of $β$ -emitting ${}^{25}{Al}$ by use of a polarized proton beam and nuclear magnetic resonance detection

High-spin positive-parity levels in ${}^{41}{Ca}$

Levels in ${}^{28}{Si}$ via the ${}^{26}{Mg} ({}^{3}{He}, n)$ reaction

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