Recent Articles

${}^{2}H (γ, π^{+}) n n$ total cross section from threshold to $Δ E = 22$ MeV

E. C. Booth, B. Chasan, J. Comuzzi, and P. Bosted

Phys. Rev. C 20, 1217 (1979) - Published 1 October, 1979

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The bremsstrahlung yield of the ${}^{2}H (γ, π^{+}) 2 n$ reaction is measured from threshold to 25 MeV above threshold. The extracted total cross section relative to the $p (γ, π^{+}) n$ cross section is 3-10% greater than the theoretical prediction.

NUCLEAR REACTIONS ${}^{2}H (γ, π^{+}) 2 n$ , bremsstrahlung end point energies to 174 MeV, measured $π^{+}$ yield, deduced $σ (E)$ .

${}^{17}O$ ( ${}^{3}{He}$ , $p$ ) ${}^{19}F$ and the structure of ${}^{19}F$

J. N. Bishop, L. R. Medsker, H. T. Fortune, and B. H. Wildenthal

Phys. Rev. C 20, 1221 (1979) - Published 1 October, 1979

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Angular distributions have been measured for 18 levels of ${}^{19}F$ populated in the reaction ${}^{17}O$ ( ${}^{3}{He}$ , $p$ ) at a bombarding energy of 18 MeV. Within the experimental resolution of 28 keV all levels below 5.7 MeV were observed. Nine states were excited with peak differential cross sections greater than 50 μb/sr, all others had maximum cross sections of less than 12 μb/sr. Eight of the nine strong levels are easily identifiable with ${(sd)}^{3}$ shell-model states. The ninth is the state at 5.11 MeV, previously assigned $J^{π} = \frac{5}{2^{-}}$ , but suggested by the present results to have positive parity. Angular distributions were analyzed with the distorted-wave Born approximation. For the strong states, transfer amplitudes were taken from an ${(sd)}^{3}$ shell-model calculation. Agreement in both shape and magnitude is good. Negative-parity hole states and positive-parity core-excited states are very weakly populated, but in many cases, their angular distributions are also well fitted with admixtures of the allowed $L$ values.

NUCLEAR REACTION ${}^{17}O$ ( ${}^{3}{He}$ , $p$ ), $E = 18.0$ MeV; ${}^{19}F$ deduced levels, $L$ , $Π$ . DWBA analysis.

Reaction ${}^{15}N$ ( $t$ , $p$ ) ${}^{17}N$

H. T. Fortune, G. E. Moore, L. Bland, M. E. Cobern, S. Mordechai, R. Middleton, and R. D. Lawson

Phys. Rev. C 20, 1228 (1979) - Published 1 October, 1979

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In ${}^{15}N$ ( $t$ , $p$ ), at $E_{t} = 15$ MeV, 19 angular distributions were measured for levels up to 7 MeV in excitation. Comparison with distorted-wave Born-approximation calculations allows extraction of $L$ values for most of them. Two different simple shell model calculations are presented for the 2p-1h states and compared with the data.

NUCLEAR REACTIONS ${}^{15}N$ ( $t$ , $p$ ), $E = 15.0$ MeV; measured $σ (E_{p}, θ)$ . Enriched gas target. DWBA analysis. ${}^{17}N$ levels deduced $L$ , $π$ , $J$ . Comparison with shell model.

Coupled-channels analysis of proton inelastic scattering to the $γ$ -vibrational band in ${}^{24}{Mg}$

L. Ray, G. S. Blanpied, and W. R. Coker

Phys. Rev. C 20, 1236 (1979) - Published 1 October, 1979

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Results are presented of coupled-channels analyses of proton inelastic scattering data for the nucleus ${}^{24}{Mg}$ , in which the $2_{2}^{+}$ , 4.24 MeV, $3^{+}$ , 5.2 MeV, $4_{2}^{+}$ , 6.01 MeV, and $5^{+}$ (?), 7.8 MeV states of the $γ$ -vibrational band are excited, at incident proton energies of 20.3, 40, and 800 MeV. Previous coupled-channels analyses of proton and $α$ particle inelastic scattering data for these states in ${}^{24}{Mg}$ have completely failed to account for the shapes and magnitudes of the $3^{+}$ , $4_{2}^{+}$ , and $5^{+}$ inelastic cross sections. In the present analysis, the inclusion of an additional nuclear vibrational multipole which permits a direct transition from the ground state to the $4_{2}^{+}$ , 6.01 MeV state is shown to provide a tremendous improvement in the theoretical description of the inelastic cross sections of all the members of the $γ$ -vibrational band, at each of the three incident proton energies considered. The same nuclear structure parameters are used at all three incident energies, along with phenomenological optical potentials specific to each energy. The new results for the $3^{+}$ , 5.2 MeV state also shed light on the energy dependence of the direct spin-flip mechanism in proton inelastic scattering.

NUCLEAR REACTIONS ${}^{24}{Mg}$ ( $p$ , $p^{'}$ ), $E_{p} = 20.3, 40, and 800$ MeV; coupled-channels analysis; deformed-vibrational model; coupling parameters.

Spin-flip probability in 13.9 MeV neutron scattering from the 1.78 MeV state of ${}^{28}{Si}$

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

Phys. Rev. C 20, 1244 (1979) - Published 1 October, 1979

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The spin-flip probability for inelastic scattering of 13.9 MeV neutrons to the $2^{+}$ (1.78 MeV) state of ${}^{28}{Si}$ was determined at nine scattering angles between 45° and 160° by measuring the neutron time-of-flight spectrum in coincidence with the de-excitation $γ$ radiation emitted perpendicular to the reaction plane. To ascertain the presence of nondirect contributions, the experimental results were compared to the predictions of microscopic and macroscopic direct reaction calculations.

NUCLEAR REACTIONS ${}^{28}{Si}$ ( $n$ , $n^{'} γ$ ), $E_{n} = 13.9$ MeV, measured $n^{'} γ (θ_{n^{'}})$ coincidences and deduced neutron spin-flip probability. Macroscopic CC and microscopic ADWBA analyses. Natural target.

Redundant states and Jost functions for nonlocal potentials

B. Bagchi, B. Mulligan, and S. B. Qadri

Phys. Rev. C 20, 1251 (1979) - Published 1 October, 1979

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This paper considers the existence of Jost solutions $f^{\pm} (k, r)$ and the Jost functions $L^{\pm} (k)$ in the presence of redundant states. The definition of $L^{\pm} (k)$ directly in terms of Fredholm determinants associated with kernels of integral equations is discussed. Examples are used to stress the importance of this relationship when the Jost solutions do not exist.

NUCLEAR REACTIONS Antisymmetrization, redundant states, nonlocal potentials, Jost solutions and Jost functions.

"Optimal" approximation to elastic projectile-nucleus scattering

S. A. Gurvitz

Phys. Rev. C 20, 1256 (1979) - Published 1 October, 1979

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An approximation which minimizes binding and recoil corrections is derived for projectile nucleus elastic scattering. We generalize previous work on single scattering and consider now multiple scattering amplitudes in this approximation. These are expressed in terms of amplitudes for elastic scattering off on-shell target nucleons and form factors. The first nonvanishing correction terms are estimated.

NUCLEAR REACTIONS Multiple scattering amplitudes, minimization of corrections, factorization, reflections, higher order corrections.

Neutron pickup from ${}^{33}S$

D. J. Crozier, A. Spadafora, and H. T. Fortune

Phys. Rev. C 20, 1267 (1979) - Published 1 October, 1979

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At a bombarding energy of 15 MeV, angular distributions have been measured for the ${}^{33}S$ ( ${}^{3}{He}$ , $α$ ) reaction leading to 25 levels of ${}^{32}S$ below 8 MeV excitation. A distorted-wave Born approximation analysis has provided $l$ values and relative spectroscopic factors for most of these. Results are in moderate agreement with shell-model calculations, but exhibit less configuration mixing than is predicted.

NUCLEAR REACTIONS ${}^{33}S$ ( ${}^{3}{He}$ , $α$ ), $E = 15$ MeV, measured $σ (E_{α}, θ)$ , enriched target; DWBA analysis, deduced $l$ , $π$ , $J$ ; comparison with shell model.

Proton optical model potential at sub-Coulomb energies for medium weight nuclei

S. Kailas, M. K. Mehta, S. K. Gupta, Y. P. Viyogi, and N. K. Ganguly

Phys. Rev. C 20, 1272 (1979) - Published 1 October, 1979

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The ( $p$ , $n$ ) reaction excitation functions for eleven nuclei from $A = 45 to 80$ measured at proton energies below ∼5 MeV have been analyzed utilizing the optical model. The real potential parameters used in the present work have been obtained by suitably combining the proton optical model parameters determined between 3 and 60 MeV. Large energy dependence of the real potential at energies below 5 MeV has been observed. The imaginary potential depths determined in the present analysis exhibit an anomalous behavior when plotted as a function of mass number $A$ . By utilizing the low and intermediate energy proton data, an attempt has been made to obtain a "global" set of optical parameters in the proton energy range between 4 and 180 MeV, for medium weight nuclei.

NUCLEAR REACTIONS ${}^{45}{Sc}$ , ${}^{48}{Ca}$ , ${}^{51}V$ , ${}^{54}{Cr}$ , ${}^{55}{Mn}$ , ${}^{59}{Co}$ , ${}^{61}{Ni}$ , ${}^{65}{Cu}$ , ${}^{71}{Ga}$ , ${}^{75}{As}$ , ${}^{80}{Se}$ ; $E$ below ∼5 MeV, analyzed $σ_{p, n}$ , optical model parameters.

Proton inelastic scattering at 12 MeV on ${}^{154}{Eu}$

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

Phys. Rev. C 20, 1279 (1979) - Published 1 October, 1979

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Scattered protons from ${}^{154}{Eu}$ were measured with an Enge split-pole spectrograph at a bombarding energy of 12 MeV. Rotational states in the ground band of ${}^{154}{Eu}$ were excited to $I^{π} = 8^{-}$ . Values of the deformation parameters were extracted from the scattering data using a coupled-channels calculation. The analysis yields $β_{2} = 0.30$ and $β_{4} = 0.04$ . A comparison of the ground band rotational properties of both ${}^{152}{Eu}$ and ${}^{154}{Eu}$ suggests that both nuclei have the same ground state configuration: $π_{\frac{5}{2}} [413]$ , $ν_{\frac{11}{2}} [505]$ .

NUCLEAR REACTIONS ${}^{154}{Eu}$ ( $p$ , $p^{'}$ ), $E_{p} = 12$ MeV; measured $E_{p}^{'}$ and $σ (θ)$ , split-pole spectrograph; adiabatic coupled-channel analysis; deduced levels, $J^{π}$ , $β_{2}$ , and $β_{4}$ ; isotopically enriched radioactive target.

NUCLEAR STRUCTURE ${}^{154}{Eu}$ , assigned Nilsson configuration.

Alpha-particle breakup at incident energies of 20 and 40 MeV/nucleon

J. R. Wu, C. C. Chang, H. D. Holmgren, and R. W. Koontz

Phys. Rev. C 20, 1284 (1979) - Published 1 October, 1979

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The breakup of alpha particles at incident energies of 20 and 40 MeV/nucleon on ${}^{27}{Al}$ , ${}^{58}{Ni}$ , ${}^{90}{Zr}$ , and ${}^{209}{Bi}$ has been studied. It was found that the breakup cross section decreases rapidly with increasing angles and increases with increasing target mass and incident energy. The total breakup yield, summed over all charged fragments, is ∼15-35% of the alpha-particle total reaction cross section, and has an approximate $A^{\frac{1}{3}}$ dependence. The ratios of breakup yields among different fragments are approximately $p : d : t : {}^{3}{He} \approx 13 : 3 : 1 : 2$ , and are roughly independent of the incident energy and the target nucleus. These features suggest that the alpha-particle fragmentation is a peripheral process and is dominated by the properties of the incident projectile. A simple plane-wave alpha-particle breakup model gives a rather good description to the experimental data. In addition to the breakup deuteron peak at half of the beam energy, a second peak at quarter of the beam energy (or the same energy as the breakup proton peak) is observed. This peak might be due to a two-step breakup-pickup process.

NUCLEAR REACTIONS ${}^{27}{Al}$ , ${}^{58}{Ni}$ , ${}^{90}{Zr}$ , ${}^{209}{Bi}$ ( $α$ , $xp$ ), ( $α$ , $xd$ ), ( $α$ , $xt$ ), ( $α$ , $x {}^{3}{He}$ ,) $E_{α} = 80, 160$ MeV; $θ = 6 ° - 30 °$ , measured $\frac{d^{2} σ}{d Ω dE}$ , deduced alpha-particle breakup yield, Comparisons with alpha-particle breakup model.

$N = 152$ shell gap and the ${}^{244}{Pu}$ ( $t$ , $p$ ) ${}^{246}{Pu}$ reaction

Ronald E. Brown, J. A. Cizewski, E. R. Flynn, and J. W. Sunier

Phys. Rev. C 20, 1301 (1979) - Published 1 October, 1979

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The ${}^{244}{Pu}$ ( $t$ , $p$ ) ${}^{246}{Pu}$ reaction has been used to examine the $N = 150 \to 152$ transition for evidence of a shell gap. Previous ( $t$ , $p$ ) experiments involving the actinide region have shown no excited $0^{+}$ states except for the ${}^{246}{Cm}$ ( $t$ , $p$ ) ${}^{248}{Cm}$ reaction, which also involves an $N = 150 \to 152$ transition. As in that case, the present reaction contains a relatively strong $L = 0$ transition having about 30% of the ground-state transition strength, at an excitation energy near 1 MeV. This result is further evidence for the presence of a gap in the Nilsson orbitals at $N = 152$ . This study is also the first examination of the excited states of ${}^{246}{Pu}$ and determines the ${}^{246}{Pu}$ mass excess to be 65.38 ± 0.02 MeV.

NUCLEAR REACTIONS ${}^{244}{Pu}$ ( $t$ , $p$ ) $E = 17$ MeV; measured $σ (θ)$ , ${}^{246}{Pu}$ mass measurement, deduced shell gap, DWBA analysis.

Systematics of carbon- and oxygen-induced fusion on nuclei with $12 \leq A \leq 19$

D. G. Kovar, D. F. Geesaman, T. H. Braid, Y. Eisen, W. Henning, T. R. Ophel, M. Paul, K. E. Rehm, S. J. Sanders, P. Sperr, J. P. Schiffer, S. L. Tabor, S. Vigdor, B. Zeidman, and F. W. Prosser, Jr.

Phys. Rev. C 20, 1305 (1979) - Published 1 October, 1979

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Measurements of the total fusion cross sections for ${}^{12}C$ + ${}^{12}C$ , ${}^{13}C$ , ${}^{14}N$ , ${}^{15}N$ , ${}^{16}O$ , ${}^{18}O$ , and ${}^{19}F$ and ${}^{16}O$ + ${}^{16}O$ have been performed over the energy range from 1.5 to 3 times the Coulomb barrier energy. Fusion barrier parameters were extracted for each system. Three systems, ${}^{12}C$ + ${}^{12}C$ , ${}^{12}C$ + ${}^{16}O$ , and ${}^{16}O$ + ${}^{16}O$ , show rather pronounced oscillatory structure in the energy dependence of the fusion cross sections. The maximum fusion cross sections for the systems studied vary by as much as 10-20%, depending on the particular entrance channel. The specific structure of the interacting nuclei clearly does have an effect; the fusion process is not entirely dominated by the macroscopic features of the ion-ion interaction.

NUCLEAR REACTIONS, fusion, measured $σ_{fusion} (E)$ ; ${}^{12}C$ + ${}^{12}C$ , $7.4 <~ E_{c . m .} <~ 31.2$ MeV; ${}^{12}C$ + ${}^{13}C$ , $7.6 <~ E_{c . m .} <~ 24.9$ MeV; ${}^{12}C$ + ${}^{14}N$ , $15.1 <~ E_{c . m .} <~ 24.0$ MeV; ${}^{12}C$ + ${}^{15}N$ , $8.9 <~ E_{c . m .} <~ 26.7$ MeV; ${}^{12}C$ + ${}^{16}O$ , $12.9 <~ E_{c . m .} <~ 27.0$ MeV; ${}^{12}C$ + ${}^{18}O$ , $11.9 <~ E_{c . m .} <~ 28.0$ MeV; ${}^{12}C$ + ${}^{19}F$ , $11.6 <~ E_{c . m .} <~ 27.1$ MeV; ${}^{16}O$ + ${}^{16}O$ , $14.9 <~ E_{c . m .} <~ 36.0$ MeV; deduced fusion barrier parameters.

Low-energy pion production with 800 MeV/N ${}^{20}{Ne}$

J. Chiba, K. Nakai, I. Tanihata, S. Nagamiya, H. Bowman, J. Ingersoll, and J. O. Rasmussen

Phys. Rev. C 20, 1332 (1979) - Published 1 October, 1979

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Doubly differential cross sections for production of positive pions ( $20 MeV \leq T_{π}^{Lab} \leq 100 MeV$ ) in bombardment of ${}^{20}{Ne}$ on NaF, Cu and Pb targets at 800 MeV/N have been measured with a range telescope. The results showed that the angular distribution of low-energy pions in the nucleon-nucleon center of mass ( $T_{π}^{c . m .} \leq 50$ MeV) was isotropic, even 90° peaking at ∼ 15 MeV c.m. The intermediate-energy pions ( $50 \leq T_{π}^{c . m .} \leq 300$ MeV) were forward and backward peaked, reflecting the individual nucleon-nucleon process in the isobar model of production. The observed cross sections were shown to be generally reproduced by an incoherent superposition of the experimental ( $p$ + nucleus) cross sections.

NUCLEAR REACTIONS NaF, Cu, $Pb ({}^{20}{Ne}, π^{+}) X$ , $\frac{E}{A} = 800$ MeV/nucleon; measured $σ (E_{π}, θ_{π})$ , $E_{π} = 20 - 100$ MeV, $θ_{π} = 30 - 150 °$ .

( ${}^{6}{Li}$ , $t$ ), ( ${}^{6}{Li}$ , ${}^{3}{He}$ ), and ( ${}^{7}{Li}$ , $t$ ) reactions into the $A = 19$ nuclei

L. M. Martz, S. J. Sanders, P. D. Parker, and C. B. Dover

Phys. Rev. C 20, 1340 (1979) - Published 1 October, 1979

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We have studied the ${}^{16}O$ ( ${}^{6}{Li}$ , $t$ ) ${}^{19}{Ne}$ , ${}^{16}O$ ( ${}^{6}{Li}$ , ${}^{3}{He}$ ) ${}^{19}F$ , and ${}^{15}N$ ( ${}^{7}{Li}$ , $t$ ) ${}^{19}F$ reactions at a laboratory angle of 15° and at incident energies of $E ({}^{6}{Li}) = 46$ MeV and $E ({}^{7}{Li}) = 40$ MeV. A selective population of final states leads to the identification of probable 3p-0h and 4p-1h configurations. Through the application of a folded-potential model to the ground-state band of ${}^{19}F$ , we provide evidence for triton clustering outside a closed-shell core. In a comparison between ( ${}^{7}{Li}$ , $t$ ) reactions leading to ${}^{19}F$ and ${}^{20}{Ne}$ , the relationship between 4p-1h and 4p-0h configurations suggests that weak-coupling structure is involved.

NUCLEAR REACTIONS ${}^{15}N$ ( ${}^{7}{Li}$ , $t$ ), $E ({}^{7}{Li}) = 40$ MeV, ${}^{16}O$ ( ${}^{6}{Li}$ , $t$ ) and ${}^{16}O$ ( ${}^{6}{Li}$ , ${}^{3}{He}$ ), $E ({}^{6}{Li}) = 46$ MeV, $θ_{lab} = 15 °$ , measured ${}^{19}{Ne}$ and ${}^{19}F$ energy levels, calculated triton-cluster states.

Single-folding model for the spin-orbit potential between ${}^{19}F$ and ${}^{28}{Si}$

M. B. Golin and S. Kubono

Phys. Rev. C 20, 1347 (1979) - Published 1 October, 1979

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A general expression for the spin-orbit potential between two heavy ions is derived using the single-folding method. This expression is applied to the calculation of the spin-orbit potential between ${}^{19}F$ and ${}^{28}{Si}$ , using single-particle as well as cluster model wave functions for ${}^{19}F$ . In the cluster model, the magnitude of the ${}^{19}F$ + ${}^{28}{Si}$ spin-orbit potential at the strong absorption radius is enhanced by a factor of 50 over the singleparticle model estimate.

NUCLEAR REACTIONS ${}^{19}F$ + ${}^{28}{Si}$ spin-orbit potential: single-folding method, single-particle, and cluster model wave functions for ${}^{19}F$ .

States in ${}^{105, 107}{Ag}$ populated by heavy-ion reactions and interpreted by a quasiparticle-plus-rotor model

Rakesh Popli, J. A. Grau, S. I. Popik, L. E. Samuelson, F. A. Rickey, and P. C. Simms

Phys. Rev. C 20, 1350 (1979) - Published 1 October, 1979

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Levels in ${}^{105, 107}{Ag}$ have been studied using heavy-ion reactions. The experiments included $γ$ -ray yields as a function of bombarding energy, $γ$ -ray angular distributions, and three-detector $γ - γ$ coincidence measurements. The positive-parity band based on the unique-parity $g_{\frac{9}{2}}$ orbital in both nuclei exhibits a $Δ I = 1$ character, unlike its counterpart $h_{\frac{11}{2}}$ band in Pd nuclei. The energy levels, $γ$ -ray mixing ratios, branching ratios, and lifetimes in this band as well as in the ground-state negative-parity band are shown to be in good agreement with calculations using a particle-plus-rotor model at a small, symmetric deformation ( $δ = 0.12$ ). The Coriolis and recoil effects are explicitly included and a variable moment of inertia is used. The low-lying "anomalous" $\frac{7}{2^{+}}$ state is also readily reproduced by this model. The calculation also shows that the $Δ I = 1$ nature of the positive-parity band results primarily from the fact that the Fermi surface is far from the $K = \frac{1}{2}$ state, whereas the transition properties are governed by the Coriolis mixing of the strong-coupled bands. Two bands built on the $\frac{17}{2^{-}}$ and $\frac{21}{2^{+}}$ states with high bandhead energies are thought to have three-quasiparticle configurations.

NUCLEAR STRUCTURE ${}^{92}{Zr}$ ( ${}^{16}O$ , $p 2 n$ ) ${}^{105}{Ag}$ at 60 MeV, ${}^{96}{Zr}$ ( ${}^{14}N$ , $3 n$ ) ${}^{107}{Ag}$ at 49 MeV: measured $I_{γ} (E ({}^{16}O))$ , $I_{γ} (E ({}^{14}N))$ , $I_{γ} (θ)$ , $γ - γ$ coin $γ - γ$ DCOQ. ${}^{105, 107}{Ag}$ deduced levels, $J$ , $π$ , $γ$ mixing ratios. Rotational model calculations, Coriolis, calculated levels, mixing ratios, branching ratios, lifetimes. Ge(Li) detectors.

Time-dependent Hartree-Fock calculations of ${}^{86}{Kr}$ + ${}^{139}{La}$ at $E_{lab} = 505, 610, and 710$ MeV

K. T. R. Davies, K. R. Sandhya Devi, and M. R. Strayer

Phys. Rev. C 20, 1372 (1979) - Published 1 October, 1979

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Time-dependent mean-field calculations, using the axially symmetric, rotating frame approximation, have been performed for the reaction ${}^{86}{Kr}$ + ${}^{139}{La}$ at $E_{lab} = 505, 610, and 710$ MeV. This is a new intermediate mass region for scattering heretofore relatively unexplored in time-dependent Hartree-Fock studies, and we obtain some results not observed in either lighter or heavier nuclear systems. At all three energies the final kinetic energy loss and angular dependence are in fair agreement with experiment, the most serious discrepancies occurring for the large-angle (small angular momentum) fully damped events whose calculated kinetic energies are about 50 MeV above the experimental ridge on the Wilczyński plots. Fusion is not seen at the two lower energies studied. However, at $E_{lab} = 710$ MeV fusion is observed for angular momenta from 0 to $65 ℏ$ , and just beyond the upper fusion limit we observe positive-angle scattering, in contrast to the negative-angle scattering always seen beyond the fusion limit for reactions of lighter ions. It is suggested that the fusion behavior for this reaction may be a definitive test of whether heavy-ion scattering is better described by a microscopic mean-field theory or macroscopic fluid dynamics. At $E_{lab} = 710$ MeV emission of alpha-like particles from the neck at scission is observed for a small range of angular momenta near $100 ℏ$ .

NUCLEAR REACTIONS ${}^{86}{Kr}$ + ${}^{139}{La}$ at $E_{lab} = 505, 610, and 710$ MeV in the timedependent Hartree-Fock approximation. Fusion and strongly damped collisions. Pre-equilibrium alpha-like emission from the neck.

Three- and four-particle transfer strengths to states in ${}^{15}N$

L. H. Harwood and K. W. Kemper

Phys. Rev. C 20, 1383 (1979) - Published 1 October, 1979

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The 9.155, 9.83, and 10.69 MeV states in ${}^{15}N$ are found to have large cross sections in both three- and four-particle transfer reactions from a study of the ${}^{12}C$ ( ${}^{7}{Li}$ , $α γ$ ), ${}^{12}C$ ( ${}^{6}{Li}$ , ${}^{3}{He} γ$ ), and ${}^{11}B$ ( ${}^{7}{Li}$ , $t γ$ ) reactions at $E_{Li} = 28, 34, and 28$ MeV, respectively. These results are in disagreement with simple cluster model arguments. Doppler shift attenuation measurements of the lifetimes of the ${}^{15}N$ states show that neither the weak-coupling shell model nor the cluster model accurately predicts the electromagnetic decay strengths in ${}^{15}N$ .

NUCLEAR STRUCTURE ${}^{12}C$ ( ${}^{7}{Li}$ , $α γ$ ), ${}^{11}B$ ( ${}^{7}{Li}$ , $t γ$ ), $E = 28$ MeV, ${}^{12}C$ ( ${}^{6}{Li}$ , ${}^{3}{He} γ$ ), $E = 34$ MeV; particle- $γ$ coincidence; Ge(Li) detectors; measured relative cross sections for all states below 10.8 MeV excitation; measured lifetimes; measured $γ$ -ray branching ratios; compared results to cluster and shell models.

Heavy-ion charge exchange reaction ${}^{28}{Si}$ ( ${}^{18}O$ , ${}^{18}F$ ) ${}^{28}{Al}$

B. T. Kim, A. Greiner, M. A. G. Fernandes, N. Lisbona, K. S. Low, and M. C. Mermaz

Phys. Rev. C 20, 1396 (1979) - Published 1 October, 1979

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The angular distribution has been measured for the $3^{+}$ and $2^{+}$ ground state doublet in ${}^{28}{Al}$ with the heavy-ion charge exchange reaction ${}^{28}{Si}$ ( ${}^{18}O$ , ${}^{18}F$ ) ${}^{28}{Al}$ at the incident beam energy of 56 MeV. It has been analyzed in terms of the microscopic one-step direct charge exchange model and the second-order DWBA approach with recoil effect taking into account the two-successive transfer: one nucleon stripping and pickup, and pickup and stripping process. The general shape of angular distribution has been reproduced by both approaches. The strength of the spin-isospin dependent two-body interaction potential extracted from one-step calculations is close to the upper limit of uncertainties reported in the light-ion charge exchange experiment. The two-step mechanism turns out to be also important and could be a competing process.

NUCLEAR REACTION ${}^{28}{Si}$ ( ${}^{18}O$ , ${}^{18}F$ ), $E = 56$ MeV; measured $σ (θ)$ ; microscopic DWRA analysis; second-order DWRA analysis with recoil effect; deduced strength of the ( $\vec{σ} \cdot \vec{σ}$ )( $\vec{τ} \cdot \vec{τ}$ ) term in the nucleon-nucleon two-body force.

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Physical Review C

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${}^{2}H (γ, π^{+}) n n$ total cross section from threshold to $Δ E = 22$ MeV

${}^{17}O$ ( ${}^{3}{He}$ , $p$ ) ${}^{19}F$ and the structure of ${}^{19}F$

Reaction ${}^{15}N$ ( $t$ , $p$ ) ${}^{17}N$

Coupled-channels analysis of proton inelastic scattering to the $γ$ -vibrational band in ${}^{24}{Mg}$

Spin-flip probability in 13.9 MeV neutron scattering from the 1.78 MeV state of ${}^{28}{Si}$

Redundant states and Jost functions for nonlocal potentials

"Optimal" approximation to elastic projectile-nucleus scattering

Neutron pickup from ${}^{33}S$

Proton optical model potential at sub-Coulomb energies for medium weight nuclei

Proton inelastic scattering at 12 MeV on ${}^{154}{Eu}$

Alpha-particle breakup at incident energies of 20 and 40 MeV/nucleon

$N = 152$ shell gap and the ${}^{244}{Pu}$ ( $t$ , $p$ ) ${}^{246}{Pu}$ reaction

Systematics of carbon- and oxygen-induced fusion on nuclei with $12 \leq A \leq 19$

Low-energy pion production with 800 MeV/N ${}^{20}{Ne}$

( ${}^{6}{Li}$ , $t$ ), ( ${}^{6}{Li}$ , ${}^{3}{He}$ ), and ( ${}^{7}{Li}$ , $t$ ) reactions into the $A = 19$ nuclei

Single-folding model for the spin-orbit potential between ${}^{19}F$ and ${}^{28}{Si}$

States in ${}^{105, 107}{Ag}$ populated by heavy-ion reactions and interpreted by a quasiparticle-plus-rotor model

Time-dependent Hartree-Fock calculations of ${}^{86}{Kr}$ + ${}^{139}{La}$ at $E_{lab} = 505, 610, and 710$ MeV

Three- and four-particle transfer strengths to states in ${}^{15}N$

Heavy-ion charge exchange reaction ${}^{28}{Si}$ ( ${}^{18}O$ , ${}^{18}F$ ) ${}^{28}{Al}$

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