Recent Articles

Photodisintegration of the alpha particle

J. S. Levinger

Phys. Rev. C 19, 2083 (1979) - Published 1 June, 1979

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I develop a formalism to calculate electric dipole transitions in the $α$ particle, expanding both initial and final states in nine-dimensional hyperspherical harmonics. I calculate results using Ballot's ground state wave function for the Volkov potential and three different exchange mixtures, giving different potentials acting in the final state. Wigner exchange gives most of the absorption in a single line: The harmonic oscillator approximation is surprisingly good for this case. An exchange force gives a satisfactory value of the integrated photoeffect cross section (120 MeV mb) and a photoeffect curve in fair agreement with Gorbunov, and Balestra et al. Extreme Born approximation is quite poor.

NUCLEAR REACTIONS Photodisintegration of alpha, hyperspherical harmonics.

${}^{4}{He}$ ( $γ$ , $p$ )-to-( $γ$ , $n$ ) cross-section ratio

T. W. Phillips, B. L. Berman, D. D. Faul, J. R. Calarco, and J. R. Hall

Phys. Rev. C 19, 2091 (1979) - Published 1 June, 1979

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We have measured the cross-section ratio $\frac{σ (γ, {}^{3}H)}{σ (γ, {}^{3}{He})}$ for ${}^{4}{He}$ from 31 to 51 MeV with an incident bremsstrahlung beam and a collimated solid-state telescope at 90° laboratory angle. The results obtained from these data for the total cross-section ratio are consistent with unity for most of the energy range covered, but deviate from this value in the energy region near 44 MeV.

NUCLEAR REACTIONS ${}^{4}{He}$ ( $γ$ , ${}^{3}H$ , ${}^{3}{He}$ , $E_{γ} = 31 - 51$ MeV; measured differential cross-section ratio at 90° (laboratory); deduced total ( $γ$ , $p$ )-to-( $γ$ , $n$ ) cross-section ratio.

( $α$ , $α p$ ) quasifree proton knockout reaction on ${}^{2}H$ , ${}^{6}{Li}$ , and ${}^{19}F$

A. Nadasen, T. A. Carey, P. G. Roos, N. S. Chant, C. W. Wang, and H. L. Chen

Phys. Rev. C 19, 2099 (1979) - Published 1 June, 1979

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The ( $α$ , $α p$ ) reaction on ${}^{2}H$ , ${}^{6}{Li}$ , and ${}^{19}F$ has been studied with 140 MeV $α$ particles. Energy spectra for the ground state transition are presented at one angle pair for ${}^{2}H$ and ${}^{19}F$ , and three angle pairs for ${}^{6}{Li}$ . Distorted-wave impulse-approximation calculations provide good fits to the ${}^{2}H$ data, the ${}^{19}F$ data, and data at one angle pair for ${}^{6}{Li}$ . The other two angle pairs for ${}^{6}{Li}$ show significant deviations from the distorted-wave impulse-approximation suggesting contributions from processes more complicated than those included in the distorted-wave impulse-approximation.

NUCLEAR REACTIONS ${}^{2}H$ , ${}^{6}{Li}$ , ${}^{19}F$ ( $α$ , $α p$ ), $E_{α} = 140$ MeV; measured ( $E_{p}$ , $E_{α}$ , $θ_{p}$ , $θ_{α}$ ); DWIA analysis; deduced spectroscopic factors.

Analyses of inelastic proton and electron scattering to the $2^{+}$ (4.43 MeV) state in ${}^{12}C$

K. Amos and I. Morrison

Phys. Rev. C 19, 2108 (1979) - Published 1 June, 1979

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Analyses of data from the inelastic scattering of 65 MeV protons and of 57 to 215 MeV electrons are used to test large basis (projected Hartree-Fock) model spectroscopies for the ground to $2_{1}^{+}$ (4.43 MeV) transition in ${}^{12}C$ . From distorted wave approximation calculations of the proton scattering, reasonably good agreement with the empirical cross section was obtained, but no spectroscopy yields the distinctive structure of the recently measured analyzing power data. In like fashion, the longitudinal form factor extracted from the electron scattering data is well reproduced by calculations based upon the same projected Hartree-Fock models of spectroscopy. The predictions of the transverse form factor, however, are quite distinctive and only in one case, and that involving a strong spin orbit effect in the basis, are the data reproduced.

NUCLEAR REACTIONS ${}^{12}C$ ( $\bar{p}$ , $p^{'}$ ) $2_{1}^{+}$ $E = 65$ MeV $σ (θ)$ , $A (θ)$ , DWA analyses using projected Hartree-Fock functions. Deduced longitudinal and transverse electron scattering form factors.

$d$ + ${}^{6}{Li}$ reactions at low energy

A. J. Elwyn and J. E. Monahan

Phys. Rev. C 19, 2114 (1979) - Published 1 June, 1979

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Recent differential and total cross-section data relating to the ${}^{6}{Li}$ ( $d$ , $α$ ) ${}^{4}{He}$ , ${}^{6}{Li}$ ( $d$ , $p$ ) ${}^{7}{Li}$ , and ${}^{6}{Li}$ ( $d$ , $n$ ) ${}^{7}{Be}$ reactions at deuteron energies between 0.1 and 1.0 MeV are analyzed in terms of the Wigner-Eisenbud formalism with the $R$ -matrix elements assumed constant, i.e., independent of the energy of the incident deuteron. For the ( $d$ , $p$ ) and ( $d$ , $n$ ) reactions the possibility of an additional coherent direct-reaction contribution is also considered. The data are reasonably well reproduced by these calculations. The results thus give an indication of the magnitude of the direct contributions to these reactions. The results also show that the observation of a resonance-like structure in, e.g., the ${}^{6}{Li}$ ( $d$ , $α$ ) ${}^{4}{He}$ reaction, does not necessarily imply a corresponding state in ${}^{8}{Be}$ .

NUCLEAR REACTIONS $R$ -matrix and DWBA analysis of ${}^{7}{Li}$ ( $d$ , $p$ ) and ${}^{6}{Li}$ ( $d$ , $n$ ) reactions, $E ≃ 0.1 - 1.0$ MeV; $R$ -matrix analysis of ${}^{6}{Li}$ ( $d$ , $α$ ) reaction, $E ≃ 0.1 - 2.0$ MeV.

Spurious solutions in few-body equations. II. Numerical investigations

Sadhan K. Adhikari

Phys. Rev. C 19, 2121 (1979) - Published 1 June, 1979

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A recent analytic study of spurious solutions in few-body equations by Adhikari and Glöckle is here complemented by numerical investigations. As proposed by Adhikari and Glöckle we study numerically the spurious solutions in the three-body Weinberg type equations and draw some general conclusions about the existence of spurious solutions in three-body equations with the Weinberg kernel and in other few-body formulations. In particular we conclude that for most of the potentials we encounter in problems of nuclear physics the three-body Weinberg type equation will not have a spurious solution which may interfere with the bound state or scattering calculation. Hence if proven convenient the three-body Weinberg type equation can be used in practical calculations. The same conclusion is true for the three-body channel coupling array scheme of Kouri, Levin, and Tobocman. In the case of the set of six coupled four-body equations proposed by Rosenberg et al. and the set of the Bencze-Redish-Sloan equations a careful study of the possible spurious solutions is needed before using these equations in practical calculations.

NUCLEAR REACTIONS Scattering theory, numerical investigations of spurious solutions, Weinberg type equations, formulations of Kouri, Levin and Tobocman; and of Bencze, Redish and Sloan.

Charged-particle emission in reactions of 15-MeV neutrons with isotopes of chromium, iron, nickel, and copper

S. M. Grimes, R. C. Haight, K. R. Alvar, H. H. Barschall, and R. R. Borchers

Phys. Rev. C 19, 2127 (1979) - Published 1 June, 1979

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Cross sections have been measured for the emission of protons, deuterons, and alpha particles for 15-MeV neutrons on ${}^{54, 56}{Fe}$ , ${}^{58, 60}{Ni}$ , ${}^{50, 52}{Cr}$ , and ${}^{63, 65}{Cu}$ , as well as on natural iron, nickel, and chromium. A quadrupole spectrometer served to detect particles with energies as low as 1 MeV. For some of the targets, a substantial fraction of the charged-particle spectrum is at energies below the Coulomb barrier. Cross sections and spectra are compared with statistical and pre-equilibrium model predictions.

NUCLEAR REACTIONS ${}^{50, 52}{Cr}$ , Cr, ${}^{54, 56}{Fe}$ , Fe, ${}^{58, 60}{Ni}$ , Ni, ${}^{63, 65}{Cu}$ , ( $n$ , $p$ ), ( $n$ , $d$ ), ( $n$ , $α$ ), $E = 14.8$ MeV; measured $σ (E_{p}, θ)$ , ( $E_{d}$ , $θ$ ), ( $E_{α}$ , $θ$ ), enriched and natural targets. Hauser-Feshbach analysis, deduced reaction mechanism.

( ${}^{3}{He}$ , $n$ ) reaction near and above $Z = 82$

R. E. Anderson, P. A. Batay-Csorba, R. A. Emigh, E. R. Flynn, D. A. Lind, P. A. Smith, C. D. Zafiratos, and R. M. DeVries

Phys. Rev. C 19, 2138 (1979) - Published 1 June, 1979

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The two-proton stripping reaction ( ${}^{3}{He}$ , $n$ ) has been studied for targets ${}^{194, 196}{Pt}$ , ${}^{204}{Hg}$ , ${}^{204, 206, 208}{Pb}$ , and ${}^{232}{Th}$ at a beam energy of 33.3 MeV. The neutrons were detected in a time-of-flight spectrometer with a nine meter flight path yielding approximately 500 keV energy resolution. The data near $Z = 82$ are analyzed in terms of a pairing vibrational model with corrections for proton particle-hole and proton-neutron pairing interactions. The results are also used to test several two-proton wave functions for levels in ${}^{210}{Po}$ , and an empirical normalization for the ( ${}^{3}{He}$ , $n$ ) reaction is extracted. The implications of these results to the energy of an "alpha-vibration" state in ${}^{208}{Pb}$ are discussed.

NUCLEAR REACTIONS ${}^{204, 206, 208}{Pb}$ , ${}^{204}{Hg}$ , ${}^{194, 196}{Pt}$ ( ${}^{3}{He}$ , $n$ ) $E = 33.3$ MeV; measured $σ (E, θ)$ , Enriched targets, DWBA analysis.

( $p$ , $t$ ) and ( $p$ , ${}^{3}{He}$ ) reactions on ${}^{33}S$

H. Nann and B. H. Wildenthal

Phys. Rev. C 19, 2146 (1979) - Published 1 June, 1979

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Angular distributions of the ${}^{33}S$ ( $p$ , $t$ ) ${}^{31}S$ and ${}^{33}S$ ( $p$ , ${}^{3}{He}$ ) ${}^{31}P$ reactions have been measured at 40 MeV bombarding energy. Unambiguous spin parity assignments of $\frac{3}{2^{+}}$ are made to levels in ${}^{31}S$ at 3.44, 4.53, and 6.27 MeV excitation energy on the basis of the observed $L = 0$ admixtures in their angular distributions. The lowest $T = \frac{3}{2}$ state in ${}^{31}S$ was observed and its excitation energy determined to 6.268±0.010 MeV. The experimental differential cross sections of transitions to low-lying mirror pairs of even parity final states in ${}^{31}S$ and ${}^{31}P$ are compared to the results of microscopic distorted-wave Born-approximation calculations based on shell-model calculations.

NUCLEAR REACTIONS ${}^{33}S$ ( $p$ , $t$ ), ${}^{33}S$ ( $p$ , ${}^{3}{He}$ ), $E_{p} = 40$ MeV; measured $σ (E_{t}, E_{{}^{3}{He}}, θ)$ ; enriched target, deduced $L$ , $J$ , $π$ values, measured $Q$ of lowest $T = \frac{3}{2}$ level in ${}^{31}S$ ; DWBA analysis.

Angular correlation measurements over the intermediate structure in ${}^{71}{As}$

G. H. Terry, H. J. Hausman, and N. Tsoupas

Phys. Rev. C 19, 2155 (1979) - Published 1 June, 1979

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Angular correlations in the ${}^{70}{Ge}$ ( $p$ , $p^{'} γ$ ) ${}^{70}{Ge}$ reaction have been measured for two of the five substructures nested in the reported $\frac{1}{2^{+}}$ intermediate structure in ${}^{71}{As}$ centered at $E_{p} = 5.05$ MeV. The spins of both substructures were determined as being $\frac{5}{2}$ or greater casting doubt on the interpretation of this cluster of states as an example of intermediate structure.

NUCLEAR REACTIONS ${}^{70}{Ge}$ ( $p$ , $p^{'} γ$ ) ${}^{70}{Ge}$ , $E = 4.95 to 5.19$ MeV. Deduced spins of resonances at $E = 5.04 and 5.14$ MeV. Enriched target.

$L = 1$ single-proton pickup reactions on ${}^{40}{Ca}$

P. D. Bond, M. J. LeVine, D. J. Pisano, C. E. Thorn, and L. L. Lee, Jr.

Phys. Rev. C 19, 2160 (1979) - Published 1 June, 1979

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In an attempt to determine the cause of the out-of-phase behavior of the angular distributions for the ( ${}^{13}C$ , ${}^{14}N$ ) $L = 1$ transfer reactions on Ca isotopes measured at 68 MeV bombarding energy, several projectiles have been used which change specific parameters in the experiment. In contrast to the 68 MeV ${}^{40}{Ca}$ ( ${}^{13}C$ , ${}^{14}N$ ) data, the results for 50 MeV ( ${}^{13}C$ , ${}^{14}N$ ), 70 MeV ( ${}^{14}N$ , ${}^{15}O$ ), and 70 MeV ( ${}^{15}N$ , ${}^{16}O$ ) reactions to the $s_{\frac{1}{2}}$ state in ${}^{39}K$ are in excellent agreement with distorted-wave Born-approximation calculations. A phasing problem between data and theory for the $d_{\frac{3}{2}}$ state in ${}^{39}K$ is present for two of these reactions, but is not as severe as with the earlier ( ${}^{13}C$ , ${}^{14}N$ ) measurement.

NUCLEAR REACTIONS ${}^{40}{Ca}$ ( ${}^{13}C$ , ${}^{14}N$ ), $E = 50$ MeV; ${}^{40}{Ca}$ ( ${}^{14}N$ , ${}^{15}O$ ), ( ${}^{15}N$ , ${}^{16}O$ ), $E = 70$ MeV; measured $σ (θ)$ . DWBA analysis.

Influence of dissipative and conservative properties on heavy-ion fusion

U. Mosel

Phys. Rev. C 19, 2167 (1979) - Published 1 June, 1979

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The sensitivity of heavy-ion fusion data to the friction form factor in classical trajectory calculations is explored. It is shown that only high energy data can be used for a test of fusion models. However, even here effects of conservative and dissipative terms are entangled with each other.

NUCLEAR REACTIONS Fusion, determination of heavy-ion potentials and dissipation strength and form factors from fusion cross sections.

Fusion and Peripheral reactions of ${}^{12}C$ + ${}^{14}N$ at energies up to 13 MeV/A

J. Gomez del Campo, R. G. Stokstad, J. A. Biggerstaff, R. A. Dayras, A. H. Snell, and P. H. Stelson

Phys. Rev. C 19, 2170 (1979) - Published 1 June, 1979

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Angular and energy distributions have been measured for reaction products of the ${}^{14}N$ + ${}^{12}C$ system at nine bombarding energies in the energy range $E_{{}^{14}N} = 34.1 to 178.1$ MeV. The fusion and direct reaction components for products from Li to Al have been determined. The experimental fusion cross sections and deduced critical angular momenta are discussed in terms of entrance channel models for compound nucleus formation and the rotating liquid drop model. Hauser-Feshbach calculations of the $Z$ distributions, energies, and angular distributions of evaporation residues are presented and compared to the data. The direct reaction yield has been analyzed with a diffraction model and is also compared with time-dependent Hartree-Fock calculations. The experimental total reaction cross section is in good agreement with optical model calculations.

NUCLEAR REACTIONS ${}^{14}N$ + ${}^{12}C$ , $E_{{}^{14}N} = 34.1 to 178.1$ MeV, measured $\frac{d^{2} σ}{d Ω dE}$ for reaction products from $Z = 3 to 13$ . Extracted $σ_{fusion}$ , $σ_{direct}$ , and $σ_{total}$ .

Reaction ${}^{12}C$ ( ${}^{16}O$ , ${}^{20}{Ne}_{g . s .}$ ) ${}^{8}{Be}_{g . s .}$ in the region $10 MeV \leq E_{c . m .} \leq 15.5 MeV$

D. A. Viggars, T. W. Conlon, F. P. Brady, and I. Naqib

Phys. Rev. C 19, 2186 (1979) - Published 1 June, 1979

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For the reaction ${}^{12}C$ ( ${}^{16}O$ , ${}^{20}{Ne}_{g . s .}$ ) ${}^{8}{Be}_{g . s .}$ angular distributions have been measured at $E_{c . m .} = 12.22, 12.57, 12.92, 13.17, 13.37, 13.77, 14.02, 14.23, 14.67, and 15.07$ MeV. The cross sections in the range $12.5 \leq E_{c . m .} \leq 13.5$ MeV are much larger than the predictions of direct $α$ -transfer and/or statistical compound nucleus calculations. Resonance behavior at 13.2 MeV with width 650 keV is indicated. Interference effects between direct and one and two resonance amplitudes have been considered with the second resonance at 13.7 MeV being a well-known anomaly $J = 8$ is indicated for these two resonances.

NUCLEAR REACTIONS ${}^{12}C$ ( ${}^{16}O$ , ${}^{20}{Ne}$ ) ${}^{8}{Be}$ , $E_{c . m .} = 10 - 15$ MeV, measured $σ (θ)$ ; compared yield to DWBA and statistical model calculations; resonance phenomena at 13.15 MeV, 13.77 MeV, deduced spin-values.

Dynamical properties of heavy-ion reactions deduced from coupled-channels calculations

D. Pelte and U. Smilansky

Phys. Rev. C 19, 2196 (1979) - Published 1 June, 1979

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The distribution of the total reaction, fusion, and direct reaction cross section in $\vec{l}$ space are studied using coupled-channels calculations. These calculations also provide information about such quantities as the polarization of highly excited states, the energy dependence of the fusion cross section, and the dependence of the total kinetic energy loss on the spins of the excited states.

NUCLEAR REACTIONS Model coupled-channels calculations; deduced $σ_{R}$ , $σ_{F}$ , $σ_{D}$ , polarization; dependence on angular momentum transfer and interactions.

Nuclear absorption effects in the elastic scattering of ${}^{10}B$ and ${}^{11}B$ by ${}^{27}{Al}$ , ${}^{28}{Si}$ , and ${}^{30}{Si}$

L. A. Parks, K. W. Kemper, R. I. Cutler, and L. H. Harwood

Phys. Rev. C 19, 2206 (1979) - Published 1 June, 1979

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Elastic scattering angular distributions for ${}^{10, 11}B$ + ${}^{27}{Al}$ , ${}^{28, 30}{Si}$ at $E_{lab} = 41.6 and 50$ MeV, ${}^{10, 11}B$ + ${}^{28}{Si}$ at $E_{lab} = 33.7$ MeV, and ${}^{11}B$ + ${}^{28}{Si}$ at $E_{lab} = 41.1 and 42.1$ MeV have been measured. At each energy all angular distributions show similar oscillatory structure for $\frac{σ}{σ_{R}} > 10^{- 3}$ , except for ${}^{11}B$ + ${}^{28}{Si}$ , which is comparatively structureless. The inelastic scattering angular distributions of the first excited $2^{+}$ states in ${}^{28}{Si}$ by ${}^{10, 11}B$ at $E_{lab} = 33.7, 41.6, and 50$ MeV, and in ${}^{30}{Si}$ by ${}^{10, 11}B$ at 50 MeV and by ${}^{10}B$ at 41.6 MeV are presented. Relative direct transfer reaction strengths for ${}^{11}B$ + ${}^{27}{Al}$ and ${}^{11}B$ + ${}^{28}{Si}$ were measured at 49.5 MeV. The differences in the measured elastic scattering angular distributions can be explained by stronger direct transfer reaction channels in ${}^{11}B$ + ${}^{28}{Si}$ .

NUCLEAR REACTIONS: ${}^{27}{Al}$ ( ${}^{10, 11}B$ , ${}^{10, 11}B$ ) ${}^{27}{Al}$ , $E = 41.6 and 50$ MeV; ${}^{28, 30}{Si}$ ( ${}^{10, 11}B$ , ${}^{10, 11}B$ ) ${}^{28, 30}{Si}$ , elastic and Si inelastic ( ${}^{28}{Si}$ , $2^{+}$ , 1.78 MeV; ${}^{30}{Si}$ , $2^{+}$ , 2.23 MeV), $E = 33.7, 41.6, and 50$ MeV. Measured $σ (θ)$ , deduced optical model parameters and Si $2^{+}$ deformation lengths. Measured particle transfer cross sections, ${}^{11}B$ + ${}^{27}{Al}$ , ${}^{28}{Si}$ $E = 49.5$ MeV, $θ_{L} = 14.7 °, 18 °, and 21 °$ .

Resonances in the ${}^{11}B$ + ${}^{12}C$ system

A. D. Frawley, J. F. Mateja, A. Roy, and N. R. Fletcher

Phys. Rev. C 19, 2215 (1979) - Published 1 June, 1979

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Excitation functions have been measured at several angles for the elastic, inelastic, ${}^{8}{Be}$ , and $α$ -particle exit channels of the ${}^{11}B$ + ${}^{12}C$ system. Nine resonances are identified in the energy range $E_{c . m .} = 9.4 to 17.8$ MeV. A comparison with resonance data from the ${}^{8}{Be}$ exit channel of the ${}^{12}C$ + ${}^{12}C$ , ${}^{12}C$ + ${}^{16}O$ , and ${}^{9}{Be}$ + ${}^{12}C$ systems is presented.

NUCLEAR REACTIONS ${}^{12}C$ ( ${}^{11}B$ , ${}^{8}{Be}$ ), ${}^{12}C$ ( ${}^{11}B$ , $α$ ), and elastic and inelastic scattering, $E_{c . m .} = 9.4 - 17.8$ MeV; measured $σ (θ, E)$ ; deduced resonances.

Inelastic scattering of ${}^{18}O$ and ${}^{17}O$ ions from medium-weight nuclei

H. Essel, K. E. Rehm, H. Bohn, H. J. Körner, and H. Spieler

Phys. Rev. C 19, 2224 (1979) - Published 1 June, 1979

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Inelastic scattering of ${}^{18}O$ and ${}^{17}O$ ions from various target nuclei in the mass range $A = 48 - 92$ has been investigated at incident energies between 54 and 69 MeV. Angular distributions for the excitation of the first excited states in the target nuclei are well reproduced by conventional distorted-wave Born approximation calculations with $B (E 2)$ values from the literature, and equal charge and mass deformation lengths. The measured angular distributions for the excitation of the first excited state in ${}^{18}O$ are, however, shifted to forward angles by 2°-5° (c.m.) with respect to the theoretical calculations. This shift is more pronounced for target nuclei near closed neutron shells. Furthermore, ${}^{18}O$ and ${}^{17}O$ induced one and two neutron transfer reactions on some of these nuclei have been measured. The systematics observed in our inelastic scattering and transfer studies suggest that two step processes including neutron transfer channels as intermediate steps are responsible for these observed shifts.

NUCLEAR REACTIONS ${}^{48}{Ti}$ ( ${}^{18}O$ , ${}^{18}O$ ), $E = 45$ MeV; ${}^{52}{Cr}$ ( ${}^{18}O$ , ${}^{18}O$ ), $E = 56$ MeV; ${}^{54}{Fe}$ ( ${}^{18}O$ , ${}^{18}O$ ), $E = 60$ MeV; ${}^{72}{Ge}$ ( ${}^{18}O$ , ${}^{18}O$ ), $E = 68.6$ MeV; ${}^{91}{Zr}$ ( ${}^{18}O$ , ${}^{18}O$ ), $E = 68.6$ MeV; ${}^{92}{Zr}$ ( ${}^{18}O$ , ${}^{18}O$ ), $E = 68.5$ MeV; measured $σ (θ)$ for g.s. and first $2^{+}$ states in ${}^{18}O$ , ${}^{48}{Ti}$ , ${}^{52}{Cr}$ , ${}^{54}{Fe}$ , ${}^{72}{Ge}$ , ${}^{92}{Zr}$ and for first $\frac{1}{2^{+}}$ state in ${}^{91}{Zr}$ . ${}^{54}{Fe}$ ( ${}^{17}O$ , ${}^{17}O$ ), $E = 59.1$ MeV; ${}^{60}{Ni}$ ( ${}^{17}O$ , ${}^{17}O$ ), $E = 62.1$ MeV; measured $σ (θ)$ for g.s. and first $2^{+}$ states in ${}^{54}{Fe}$ , ${}^{60}{Ni}$ and for first $\frac{1}{2^{+}}$ state in ${}^{17}O$ . ${}^{72}{Ge}$ ( ${}^{18}O$ , ${}^{18}O$ ), $E = 30 - 48$ MeV, $θ_{lab} = 175 °$ ; measured $σ (E)$ for the first $2^{+}$ states in ${}^{72}{Ge}$ and ${}^{18}O$ . ${}^{54}{Fe}$ ( ${}^{18}O$ , ${}^{17}O$ ), $E = 56$ MeV; ${}^{120}{Sn}$ ( ${}^{18}O$ , ${}^{17}O$ ), $E = 72$ MeV; measured $σ (θ)$ for low lying states. ${}^{54}{Fe}$ ( ${}^{17}O$ , ${}^{16}O$ ), $E = 59.1$ MeV; ${}^{60}{Ni}$ ( ${}^{17}O$ , ${}^{16}O$ ), $E = 62.1$ MeV; measured $σ (θ)$ for low lying states. Optical model, DWBA, deformation parameters. Enriched targets.

Gross and intermediate-width structure in the interaction of ${}^{16}O$ with ${}^{16}O$

J. J. Kolata, R. M. Freeman, F. Haas, B. Heusch, and A. Gallmann

Phys. Rev. C 19, 2237 (1979) - Published 1 June, 1979

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The complete fusion cross section and the individual yields of the 12 most abundant nuclides produced have been determined for the ${}^{16}O$ + ${}^{16}O$ system in the energy region from 30-40 MeV (c.m.). The individual production cross sections from this and an earlier experiment at lower energies are compared with the predictions of a spin-dependent evaporation model calculation. The comparison, though not completely satisfactory, nevertheless provides no evidence that such models are inadequate to explain the observations. The measured production cross sections are also used to deduce a new normalization for existing low-energy ${}^{16}O$ + ${}^{16}O$ reaction cross section data. Striking periodic gross structure observed in the complete fusion cross section is compared with the total reaction cross section predictions of the optical model, using several different potentials. Good agreement is obtained for surface-transparent and, in particular, angular-momentum-dependent potentials. Additional intermediate-width anomalies are identified at $E_{c . m .} = 30.5, 35, and 38.5$ MeV in the ${}^{16}O$ ( $3^{-}$ ) and ${}^{20}{Ne}$ channels.

NUCLEAR REACTIONS Complete fusion, ${}^{16}O$ + ${}^{16}O$ , $E_{c . m .} = 12 - 40$ MeV, measured $σ (E)$ for production of 12 nuclides; $γ$ -ray measurement, Ge(Li) detectors and natural target; deduced total fusion $σ$ ; evaporation-model analysis of nuclide distribution; optical-model analysis of total reaction cross sections; extracted barrier and critical parameters; deduced new normalization for existing low-energy ${}^{16}O$ + ${}^{16}O$ reaction cross sections.

Mechanism of the ${}^{26}{Mg}$ ( ${}^{18}O$ , ${}^{16}O$ ) ${}^{28}{Mg}$ reaction at $E_{{}^{18}O} = 50$ MeV and the energy levels of ${}^{28}{Mg}$

M. Bernas, M. Roy-Stephan, F. Pougheon, M. Langevin, G. Rotbard, P. Roussel, J. P. LeFèvre, M. C. Lemaire, K. S. Low, and B. H. Wildenthal

Phys. Rev. C 19, 2246 (1979) - Published 1 June, 1979

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The reaction ${}^{26}{Mg}$ ( ${}^{18}O$ , ${}^{16}O$ ) ${}^{28}{Mg}$ has been studied at a bombarding energy of 50 MeV between laboratory angles of 4° and 17°. The differential cross sections of the lowest four states of ${}^{28}{Mg}$ have been compared to exact finite-range calculations in the distorted-wave Born approximation and coupled-channels Born approximation formulations. The reaction-mechanism calculations employed wave functions for the initial and final nuclear states which were generated in shell-model calculations carried out in the full $d_{\frac{5}{2}} - s_{\frac{1}{2}} - d_{\frac{3}{2}}$ basis space. The relative importance of one-step and two-step processes in the population of the different final states is evaluated and the effectiveness of current reaction theories in accounting for phenomena such as are exemplified by the present data is discussed.

NUCLEAR REACTIONS ${}^{26}{Mg}$ ( ${}^{18}O$ , ${}^{16}O$ ) ${}^{28}{Mg}$ ; enriched target, $E = 50$ MeV, measured $σ (θ)$ , microscopic DWBA and CCBA analysis with shell-model wave functions; deduced levels of ${}^{28}{Mg}$ .

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Photodisintegration of the alpha particle

${}^{4}{He}$ ( $γ$ , $p$ )-to-( $γ$ , $n$ ) cross-section ratio

( $α$ , $α p$ ) quasifree proton knockout reaction on ${}^{2}H$ , ${}^{6}{Li}$ , and ${}^{19}F$

Analyses of inelastic proton and electron scattering to the $2^{+}$ (4.43 MeV) state in ${}^{12}C$

$d$ + ${}^{6}{Li}$ reactions at low energy

Spurious solutions in few-body equations. II. Numerical investigations

Charged-particle emission in reactions of 15-MeV neutrons with isotopes of chromium, iron, nickel, and copper

( ${}^{3}{He}$ , $n$ ) reaction near and above $Z = 82$

( $p$ , $t$ ) and ( $p$ , ${}^{3}{He}$ ) reactions on ${}^{33}S$

Angular correlation measurements over the intermediate structure in ${}^{71}{As}$

$L = 1$ single-proton pickup reactions on ${}^{40}{Ca}$

Influence of dissipative and conservative properties on heavy-ion fusion

Fusion and Peripheral reactions of ${}^{12}C$ + ${}^{14}N$ at energies up to 13 MeV/A

Reaction ${}^{12}C$ ( ${}^{16}O$ , ${}^{20}{Ne}_{g . s .}$ ) ${}^{8}{Be}_{g . s .}$ in the region $10 MeV \leq E_{c . m .} \leq 15.5 MeV$

Dynamical properties of heavy-ion reactions deduced from coupled-channels calculations

Nuclear absorption effects in the elastic scattering of ${}^{10}B$ and ${}^{11}B$ by ${}^{27}{Al}$ , ${}^{28}{Si}$ , and ${}^{30}{Si}$

Resonances in the ${}^{11}B$ + ${}^{12}C$ system

Inelastic scattering of ${}^{18}O$ and ${}^{17}O$ ions from medium-weight nuclei

Gross and intermediate-width structure in the interaction of ${}^{16}O$ with ${}^{16}O$

Mechanism of the ${}^{26}{Mg}$ ( ${}^{18}O$ , ${}^{16}O$ ) ${}^{28}{Mg}$ reaction at $E_{{}^{18}O} = 50$ MeV and the energy levels of ${}^{28}{Mg}$

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