Recent Articles

RAPID COMMUNICATION

Alpha decay of neutron deficient polonium and bismuth isotopes

M. E. Leino, S. Yashita, and A. Ghiorso

Phys. Rev. C 24, 2370(R) (1981) - Published 1 November, 1981

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Neutron deficient isotopes of polonium and bismuth have been produced in the reactions ${}^{56}{Fe}$ + ${}^{nat}{Ce}$ and ${}^{56}{Fe}$ + ${}^{141}\Pr$ , separated from the primary beam by our gas-filled on-line mass separator. The half-lives have been determined by measuring the lifetimes of individual nuclei. The new isotope ${}^{192}{Po}$ ( $T_{\frac{1}{2}} = 34 \pm 3$ ms, $E_{α} = 7.17$ MeV) and a short-lived isomeric state in ${}^{191}{Bi}$ ( $T_{\frac{1}{2}} = 150 \pm 15$ ms, $E_{α} = 6.86$ MeV) have been identified.

RADIOACTIVITY ${}^{192, 193, 194}{Po}$ , ${}^{193}{Po}^{m}$ , and ${}^{191}{Bi}^{m}$ ; measured $T_{\frac{1}{2}}$ , $E_{α}$ . Gas-filled on-line mass separator.

RAPID COMMUNICATION

Direct $γ$ transitions in ${}^{12}C$ + ${}^{12}C$

R. L. McGrath, D. Abriola, J. Karp, T. Renner, and S. Y. Zhu

Phys. Rev. C 24, 2374(R) (1981) - Published 1 November, 1981

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Preliminary results of an experiment to detect $γ$ transitions between the high energy particle unstable structures known in the ${}^{12}C$ + ${}^{12}C$ system are reported. The specific process investigated is ( ${}^{12}C$ + ${}^{12}C$ ) 25.8 MeV (c.m.) → $γ$ + ( ${}^{12}C$ + ${}^{12}C$ ) 19.3 MeV (c.m.) → $γ$ + ${}^{12}C$ + ${}^{12}C$ (g.s. or $2^{+}$ ). The initial energy is near the center of the gross structure thought to have $J^{π} = 14^{+}, and 19.3$ MeV is the energy of the $12^{+}$ intermediate width resonance. An upper limit (one standard deviation) is found ${(\frac{Γ_{γ}}{Γ})}_{25.8 Mev} ≲ (2 to 8) \times 10^{- 6}$ depending on the analysis procedure. This result shows there is no collective $γ$ decay between the intermediate width resonances at the energies studied here, and is comparable in size and consistent with resonance-fragmentation models but does not exclude nonresonant ones.

NUCLEAR REACTIONS Compared ${}^{12}C$ + ${}^{12}C$ → $γ$ + ( ${}^{12}C$ + ${}^{12}C$ ) and ${}^{12}C$ ( $2^{+}$ ) + ${}^{12}C$ ( $2^{+}$ ) $σ$ 's; $E_{lab} = 25.8$ MeV; deduced $\frac{Γ_{γ}}{Γ}$ upper limit.

RAPID COMMUNICATION

Search for a giant resonance built on the 16.6-MeV state in ${}^{8}{Be}$

S. Manglos, N. R. Roberson, H. R. Weller, and D. R. Tilley

Phys. Rev. C 24, 2378(R) (1981) - Published 1 November, 1981

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The yield curve for proton capture on ${}^{7}{Li}$ , leading to the region of the isospin-mixed pair of states at $E_{x} = 16.63 and 16.92$ MeV in ${}^{8}{Be}$ , has been measured as a function of bombarding energy from 4 to 30 MeV. A direct capture model provides a good description of the data.

NUCLEAR REACTIONS ${}^{7}{Li} (p, γ) {}^{8}{Be}^{*} \to 2 α$ ; measured $σ (E, θ)$ leading to the 16.6-16.9-MeV states for $E_{p} = 11.5 to 30$ MeV by $γ$ -ray detection. Measured $σ (E)$ for $E_{p} = 4 to 13$ MeV by detection of $2 α$ . Natural target. Compared to direct capture model.

RAPID COMMUNICATION

Nuclear axion decay

Augusto Barroso and Nimai C. Mukhopadhyay

Phys. Rev. C 24, 2382(R) (1981) - Published 1 November, 1981

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RAPID COMMUNICATION

High-spin isomer in ${}^{211}{Rn}$ , and the shape of the yrast line

G. D. Dracoulis, C. Fahlander, and A. R. Poletti

Phys. Rev. C 24, 2386(R) (1981) - Published 1 November, 1981

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High-spin yrast states in ${}^{211}{Rn}$ have been identified. A ${\frac{61}{2}}^{-}$ , 380 ns isomer found at 8856 keV is characterized as a core-excited configuration. The average shape of the yrast line is smoother than that of its neighbor ${}^{212}{Rn}$ . This difference is attributed to the presence of the neutron hole.

NUCLEAR REACTIONS ${}^{198}{Pt}$ ( ${}^{18}O$ , $5 n$ ) ${}^{211}{Rn}$ , $E = 96$ MeV, measured $σ (E, E γ)$ , $γ - γ$ coincidences, deduced levels, measured $n - γ$ coincidence, $σ (θ)$ , conversion electrons, deduced lifetimes, spins, parities. High-spin isomer, yrast line shape, core-excited configurations.

RAPID COMMUNICATION

Structure in the reaction channels of ${}^{14}C$ + ${}^{14}C$

R. M. Freeman, C. Beck, F. Haas, B. Heusch, H. Bohn, U. Käufl, K. A. Eberhard, H. Puchta, T. Senftleben, and W. Trautmann

Phys. Rev. C 24, 2390(R) (1981) - Published 1 November, 1981

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The reaction channels of ${}^{14}C$ + ${}^{14}C$ have been studied from $E_{c . m .} = 12.5 to 32.5$ MeV by $γ$ -ray techniques. Correlated oscillatory structure has been observed in inelastic, transfer, and fusion-evaporation channels. These features are comparable to the behavior of ${}^{16}O$ + ${}^{16}O$ where similar dynamical conditions prevail.

NUCLEAR REACTIONS ${}^{14}C$ + ${}^{14}C$ , $E_{c . m .} = 12.5 - 32.5$ MeV, measured $I_{γ}$ . Deduced resonant structure in reaction channels. Enriched target.

Erratum: Gamma-ray widths in ${}^{15}N$

R. Moreh, W. C. Sellyey, and R. Vodhanel

Phys. Rev. C 24, 2394 (1981) - Published 1 November, 1981

Coulomb effects on charged particle exchange singularities

F. D. Santos

Phys. Rev. C 24, 1379 (1981) - Published 1 October, 1981

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Coulomb effects on the singularities of charged particle exchange scattering amplitudes are discussed. It is shown that the nature of the exchange singularity depends on the value of $η$ and that the amplitude is finite for $η > 1$ . Coulomb correction factors which include the effects of Coulomb distortion are given for a suitably defined exchange pole residue in the cross section. The implications of these results on determinations of the asymptotic $D$ - to $S$ -state ratio in the deuteron, ${}^{3}H$ , and ${}^{3}{He}$ are discussed.

NUCLEAR REACTIONS Coulomb corrections in charged particle exchange amplitudes.

Approximate Coulomb correction to elastic $N - d$ scattering

H. Zankel and G. M. Hale

Phys. Rev. C 24, 1384 (1981) - Published 1 October, 1981

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An approximate Coulomb correction that includes Coulomb distortion of the strong amplitudes is used to relate observables for the charge-symmetric branches of $N - N$ and $N - d$ scattering. The approximate correction is nearly identical with an exact calculation for $N - N$ scattering, and tends to account better for the differences between $p - d$ measurements and three-body $n - d$ calculations than Coulomb corrections currently used.

NUCLEAR REACTIONS Coulomb correction for mirror reactions; applied to $N - N$ and $N - d$ scattering; predicted polarizations for $n - d$ scattering from $p - d$ phase shifts.

Treiman-Yang criterion as a test of the pole approximation in the ${}^{9}{Be}$ ( ${}^{3}{He}$ , $α α$ ) ${}^{4}{He}$ reaction

P. G. Fallica, M. Lattuada, F. Riggi, C. Spitaleri, C. M. Sutera, and D. Vinciguerra

Phys. Rev. C 24, 1394 (1981) - Published 1 October, 1981

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The ${}^{9}{Be}$ ( ${}^{3}{He}$ , $α α$ ) ${}^{4}{He}$ reaction has been studied at low incident energy to test the predictions of the pole approximation. Treiman-Yang distributions have been deduced from the measured differential cross sections for a wide range of the Treiman-Yang angle and of the spectator momentum. The data are consistent with the isotropic distribution predicted by the pole mechanism.

NUCLEAR REACTIONS ${}^{9}{Be}$ ( ${}^{3}{He}$ , $α α$ ) ${}^{4}{He}$ , $E_{{}^{3}{He}} = 2.8$ MeV; measured $\frac{d^{3} σ}{d Ω_{1} d Ω_{2} d E_{1}}$ ; deduced Treiman-Yang distributions.

Antisymmetrized elastic scattering and optical potential theory

A. Picklesimer

Phys. Rev. C 24, 1400 (1981) - Published 1 October, 1981

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A recently proposed formalism for incorporating Pauli symmetries into the conventional theory of the optical potential is further developed and explored. This formalism has a certain flexibility in that the optical potential depends upon the choice of the symmetrized transition operator used to define it. One choice has been shown to lead to an appealing multiple scattering treatment, while another imparts desirable unitarity properties and lends itself to a resonance analysis. We define a generalized spectator expansion which elucidates the multiple scattering structure of the latter choice. This leads to remarkable results, as well as to the connection between the optical potentials for the two choices within the multiple scattering framework. The resonance analysis is further explicated and extended and the relationship of the corresponding optical potential to the Feshbach formalism is described. A direct connection between the new formalism and the antisymmetrized Feshbach formalism is derived. These results yield a unified overview of the antisymmetrized optical potential theory for elastic scattering.

NUCLEAR REACTIONS Pauli symmetries incorporated into elastic scattering and optical potential theory. Generalized spectator expansion, multiple scattering, resonance analysis. Unified overview of antisymmetrized elastic scattering optical potential theory.

Nuclear level densities from resonance averaged neutron capture $γ$ -ray spectra

Marion L. Stelts, Robert E. Chrien, and Mary K. Martel

Phys. Rev. C 24, 1419 (1981) - Published 1 October, 1981

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High resolution measurements of the spectra of $γ$ rays from the capture of neutrons by nuclei, if averaged over a sufficient number of neutron resonances, allow the determination of all final states in a spin-parity range accessible to electric-dipole transitions. For the range of excitation energy where each final state is adequately resolved and the excitation is high enough for a statistical description of those states to be applicable, these data can be used to test nuclear level density formulas. Data are presented for 11 nuclei ranging from ${}^{148}{Sm}$ to ${}^{239}U$ and compared with a back-shifted Fermi-gas model.

NUCLEAR REACTIONS ${}^{127, 149, 154}{Sm}$ ( $\bar{n}$ , $γ$ ); ${}^{165}{Ho}$ ( $\bar{n}$ , $γ$ ); ${}^{167}{Er}$ ( $\bar{n}$ , $γ$ ); ${}^{181}{Ta}$ ( $\bar{n}$ , $γ$ ); ${}^{182}W$ (( $\bar{n}$ , $γ$ ); ${}^{189}{Os}$ ( $\bar{n}$ , $γ$ ); ${}^{195}{Pt}$ ( $\bar{n}$ , $γ$ ); ${}^{197}{Au}$ ( $\bar{n}$ , $γ$ ); ${}^{236, 238}U$ ( $\bar{n}$ , $γ$ ). $E n = 2 keV, 24 keV$ resonance-averaged neutron capture gamma-rays level densities deduced product nuclei. Separated targets. Comparison to Fermi-gas model.

Structure of ${}^{94}{Tc}$

E. Adamides, L. D. Skouras, and A. C. Xenoulis

Phys. Rev. C 24, 1429 (1981) - Published 1 October, 1981

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The level structure and decay properties of levels in ${}^{94}{Tc}$ up to 2307 keV of excitation have been investigated via measurements of excitation functions of singles $γ$ rays and via $n γ$ - and $γ γ$ -coincidence experiments following the ${}^{94}{Mo}$ ( $p$ , $n γ$ ) reaction with proton energies between 5.0 and 8.0 MeV. From these experiments and from high resolution singles energy and directional-correlation measurements an extended decay scheme has been obtained which included 42 levels in ${}^{94}{Tc}$ and incorporated 180 $γ$ rays. New levels at 797.9 ( $2^{-}$ ), 823.2( $2^{+}$ ), 917.7( $3^{+}$ ), 926.3( $4^{+}$ ), 953.5( $3^{-}$ ), 1045.1( $2^{+}$ ), 1178.4( $2^{-}$ , $3^{-}$ ), 1263.9( $3^{+}$ ), 1314.1( $4^{(-)}$ ), 1351.7( $3^{-}$ ), 1364.9( $2^{+}$ ), 1394.2( $3^{-}$ ), 1406.8( $3^{+}$ ), 1429.3( $1^{+}$ ), 1540.0( $3^{+}$ ), 1659.9, 1679.0, 1778.4, 1856.8, 1865.2, 1884.0, 1973.5, 2002.1, 2094.4, 2131.8, 2167.0, 2208.2, 2213.5, 2241.6, 2264.4, 2267.8, and 2306.6 keV with the assigned $J^{π}$ values in parentheses were postulated. The singles directional correlations for many transitions provided (i) reliable branching ratios, (ii) $J^{π}$ assignments, and (iii) multipole mixing ratios from analysis of the correlations via the compound statistical theory for nuclear reactions. Lifetimes for 18 states in ${}^{94}{Tc}$ were obtained by the Doppler-shift-attenuation method via the ${}^{94}{Mo}$ ( $p$ , $n γ$ ) reaction at 7.2 MeV. The lifetimes were extracted from singles spectra taken in the presence of standards at eight angles between 0° and 110° to the beam direction by employing a centroid shift analysis of the data. For a good number of transitions in ${}^{94}{Tc}$ values or limits for $B (E 1)$ , $B (E 2)$ , and $B (M 1)$ were obtained. The positive-parity levels up to 1.711 MeV of excitation and their decay properties were calculated in the shell-model framework and are compared with the corresponding experimental quantities.

NUCLEAR REACTIONS ${}^{94}{Mo}$ ( $p$ , $n γ$ ) ${}^{94}{Tc}$ , $E_{p} = 5.0 - 8.0$ MeV, enriched targets. Measured $E_{γ}$ , $I_{γ}$ , $I_{γ} (θ)$ , $σ (Ep)$ , $Δ E γ (τ)$ , $γ - γ$ coin, $n - γ$ coin, deduced ${}^{94}{Tc}$ levels, thresholds, branching ratios, $τ$ , $δ (\frac{E 2}{M 1})$ , $B (E 2)$ , $B (M 1)$ , and $B (E 1)$ values, Ge(Li) detectors, NE-213 scintillator detector. Calculated ${}^{94}{Tc}$ positive-parity levels, $B (E 2)$ , $B (M 1)$ , $τ$ , and branching ratios.

Evidence for $J$ dependence in ${}^{60}{Ni}$ ( ${}^{3}{He}$ , $d$ ) ${}^{61}{Cu}$ cross sections

J. E. Kim and W. W. Daehnick

Phys. Rev. C 24, 1461 (1981) - Published 1 October, 1981

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The ${}^{60}{Ni}$ ( ${}^{3}{He}$ , $d$ ) ${}^{61}{Cu}$ reaction was studied in order to investigate $j$ -dependent effects at small angles. Absolute differential cross sections were measured in small angular steps over the range $1.6 ° \leq θ \leq 40 °$ . A high-resolution position-sensitive (helix) gas counter in the focal plane of a spectrograph was used as a detector. The total energy resolution ranged from 12 to 15 keV. Orbital angular momentum transfers and spectroscopic factors were extracted from comparison with distorted-wave Born-approximation (DWBA) calculations for the levels up to 3.86 MeV in ${}^{61}{Cu}$ . Many higher-lying $l = 1 and 3$ and one $l = 2$ transitions are newly observed. Angular distributions for known $f_{\frac{5}{2}}$ stripping showed a 2-3° forward shift of stripping peak positions relative to $f_{\frac{7}{2}}$ transfers. For $l = 1$ transitions small-angle (0°-5°) cross sections of the $p_{\frac{1}{2}}$ transfers are appreciably enhanced whereas the angular shapes of known $p_{\frac{3}{2}}$ states are in excellent agreement with the distorted-wave Born approximation. Distorted-wave Born approximation calculations which include spin-orbit effects in the entrance and exit channels do not reproduce these $j$ -dependent differences.

NUCLEAR REACTIONS ${}^{60}{Ni}$ ( ${}^{3}{He}$ , $d$ ) ${}^{61}{Cu}$ , $E_{{}^{3}{He}} = 18$ MeV; measured $σ (E_{d} θ)$ , resolution ∼13 keV. DWBA analysis, deduced $l$ , $π$ , spectroscopic factors, small angle $l = 1, 3$ $j$ dependence.

Energy dependence of the ${}^{208}{Pb}$ ( ${}^{4}{He}$ , $t$ ) and ( ${}^{4}{He}$ , ${}^{3}{He}$ ) reaction from 10 to 20 MeV/nucleon

R. Perry, A. Nadasen, D. L. Hendrie, P. G. Roos, and N. S. Chant

Phys. Rev. C 24, 1471 (1981) - Published 1 October, 1981

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Alpha particle elastic scattering from ${}^{208}{Pb}$ and the ${}^{208}{Pb}$ ( ${}^{4}{He}$ , $t$ ) ${}^{209}{Bi}$ and ${}^{208}{Pb}$ ( ${}^{4}{He}$ , ${}^{3}{He}$ ) ${}^{209}{Pb}$ reactions have been measured at 39.8, 61.5, and 81.4 MeV. Distorted-wave Born approximation calculations, including finite range effects, provide spectroscopic factors for the lowest levels which are generally energy independent to within 15%. This result is in contrast to published ${}^{16}O$ + ${}^{208}{Pb}$ single nucleon transfer studies which show a factor of approximately four variation in the spectroscopic factor over the same MeV/nucleon energy range.

NUCLEAR REACTIONS ${}^{208}{Pb}$ ( $α$ , $α$ ), ( $α$ , ${}^{3}{He}$ ), ( $α$ , $t$ ), $E_{α} = 39.8, 61.5, 81.4$ MeV, measured $σ (θ)$ , enriched target; optical model analysis, DWBA analysis, deduced spectroscopic factors.

Velocity dependence of transient hyperfine field at Pt ions rapidly recoiling through magnetized Fe

A. E. Stuchbery, C. G. Ryan, and H. H. Bolotin

Phys. Rev. C 24, 1480 (1981) - Published 1 October, 1981

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The velocity dependence of the transient hyperfine magnetic field acting at nuclei of ${}^{196}{Pt}$ ions rapidly recoiling through thin magnetized Fe was investigated at a number of recoil velocities. The state of interest ( $2_{1}^{+}$ ) was populated by Coulomb excitation using beams of 80- and 120-MeV ${}^{32}S$ and 150- and 220-MeV ${}^{58}{Ni}$ ions. The $2_{1}^{+}$ → $0_{1}^{+}$ $γ$ -ray angular distribution precession measurements were carried out in coincidence with backscattered projectiles. From these results, the strength of the transient field acting on Pt ions recoiling through magnetized Fe with average velocities in the extended range $2.14 \leq 〈 \frac{v}{v_{0}} 〉 \leq 4.82$ ( $v_{0} = \frac{c}{137}$ ) was found to be consistent with a linear velocity dependence and to be incompatible with the specific $v^{0.45 \pm 0.18}$ dependence which has been previously reported to account well for all ions in the mass range from oxygen through samarium. This seemingly singular behavior for Pt and other ions in the Pt mass vicinity is discussed.

NUCLEAR REACTIONS ${}^{196}{Pt}$ ( ${}^{32}S$ , ${}^{32}S$ ') ${}^{196}{Pt}$ ( $2_{1}^{+}$ ), ${}^{196}{Pt}$ ( ${}^{58}{Ni}$ , ${}^{58}{Ni}$ ') ${}^{196}{Pt}$ ( $2_{1}^{+}$ ), $E_{s} = 80 and 120$ MeV, $E_{Ni} = 150 and 220$ MeV, enriched target; measured $W (θ, H, \infty)$ in thin polarized Fe. Deduced transient field and velocity dependence of $Pt Fe$ for $\frac{v}{c} \leq 3.84 %$ .

Level structure of ${}^{70}{Se}$

A. Ahmed, A. V. Ramayya, D. L. Sastry, J. H. Hamilton, R. B. Piercey, H. Kawakami, A. P. de Lima, C. F. Maguire, R. L. Robinson, H. J. Kim, J. C. Wells, and A. C. Rester

Phys. Rev. C 24, 1486 (1981) - Published 1 October, 1981

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The level structure of ${}^{70}{Se}$ was studied via the ${}^{58}{Ni}$ ( ${}^{14}N$ , $pn$ ) ${}^{70}{Se}$ reaction at a beam energy of 38 MeV. Measurements were made of $γ$ -ray singles and $γ - γ$ coincidence spectra, $γ$ -ray angular distributions, and $γ - γ$ directional correlations. Level energies, decay modes, spins and parities, $γ$ -ray mixing ratios, and $γ$ -ray branching ratios were deduced. The levels in the yrast band through $8^{+}$ , a tentative second ( $0^{+}$ ) state at 2011.2 keV, and a $3^{-}$ state at 2519.2 keV are some of the new results obtained from the present investigation. The moment-of-inertia plot shows a break around $6^{+}$ for the yrast levels, which is attributed to band crossing. Interacting boson approximation calculations were performed and are compared with the experimental values for the energy levels.

NUCLEAR REACTIONS ${}^{58}{Ni}$ ( ${}^{14}N$ , $pn$ ) ${}^{70}{Se}$ , $E = 38$ MeV; measured $E_{γ}$ , $I_{γ}$ , $γ (θ)$ , $γ γ (θ)$ ; ${}^{70}{Se}$ deduced levels, $J$ , $π$ , $δ$ , $γ$ branching.

Folding-model description of elastic and inelastic scattering of ${}^{9}{Be}$ by ${}^{40, 44}{Ca}$ and ${}^{39}K$ at 40 MeV

V. Hnizdo, J. Szymakowski, K. W. Kemper, and J. D. Fox

Phys. Rev. C 24, 1495 (1981) - Published 1 October, 1981

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Angular distributions have been measured for elastic scattering of ${}^{9}{Be}$ + ${}^{40, 44}{Ca}$ and ${}^{9}{Be}$ + ${}^{39}K$ at $E_{lab} = 40$ MeV, covering an angular range up to $θ_{c . m} = 120 ° (\frac{σ}{σ_{R}} ≃ 10^{- 5})$ , and for inelastic scattering of ${}^{9}{Be}$ leading to the first $2^{+}$ , $3^{-}$ , and $5^{-}$ states in ${}^{40}{Ca}$ , and the first $2^{+}$ state in ${}^{44}{Ca}$ . The large angle cross sections ( $θ_{c . m .} = 173 °$ ) measured are an order of magnitude smaller than those reported earlier for ${}^{6}{Li}$ scattering in this mass region. The data are analyzed in terms of the double-folding model with a realistic effective nucleon-nucleon interaction. The need to renormalize the effective interaction by a factor of ∼0.6 is removed when the strong projectile quadrupole effects are treated explicitly in coupled channels calculations. The inelastic cross sections are dominated by the imaginary part of the transition form factor, but the deformation lengths still agree well with the experimental $B (EL)$ values for the $L = 2, 3, and 5$ transitions studied.

NUCLEAR REACTIONS ${}^{9}{Be}$ + ${}^{39}K$ , ${}^{40, 44}{Ca}$ , $E = 40$ MeV; elastic and inelastic, ${}^{40}{Ca}$ ( $2^{+}$ , 3.90 MeV, $3^{-}$ , 3.74 MeV, and $5^{-}$ , 4.49 MeV) and ${}^{44}{Ca}$ ( $2^{+}$ , 1.16 MeV). Measured $σ (θ)$ up to $θ_{c . m .} = 120 °$ and at $θ_{c . m .} = 173.8 °$ . Double-folding model analysis, DWBA, deduced nuclear deformation lengths.

Molecular resonance effects in heavy ion excitation functions

S. Y. Lee, Y. H. Chu, and T. T. S. Kuo

Phys. Rev. C 24, 1502 (1981) - Published 1 October, 1981

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The inelastic and fusion excitation functions are analyzed using an interference mechanism between the barrier and internal waves of the heavy ion optical potential. The undamped overlapping molecular resonances are found to be the main dynamical mechanism for the gross oscillations in the excitation function. Our result suggests a rather interesting correlation between the total reaction excitation and the direct surface reaction excitation function. Its origin may be understood as follows: At the resonance, the wave function is pulled into the nuclear interior, and thus, the total reaction cross section is at maximum. The direct surface reaction is, however, shifted by a small phase difference near the surface region. This picture should be valid in the case of overlapping molecular resonance of the heavy ion systems. Good agreement between calculated and experimental inelastic and fusion excitation functions for ${}^{12}C$ + ${}^{12}C$ and ${}^{16}O$ + ${}^{16}O$ is obtained.

NUCLEAR REACTIONS Effect of molecular resonance to the gross oscillation in heavy ion inelastic and fusion excitation functions.

Intermediate structure and statistical fluctuations in the ${}^{12}C$ + ${}^{24}{Mg}$ system

M. C. Mermaz, A. Greiner, B. T. Kim, M. J. LeVine, E. Müller, M. Ruscev, M. Petrascu, M. Petrovici, and V. Simion

Phys. Rev. C 24, 1512 (1981) - Published 1 October, 1981

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The 180° c.m. excitation function of the elastic and inelastic scattering of ${}^{12}C$ on a ${}^{24}{Mg}$ target has been measured between 12- and 27-MeV c.m. energy. A statistical analysis of the data has been performed and it has turned out that the presence of intermediate structures cannot be completely ruled out in the compound dinuclear system ${}^{36}{Ar}$ . Unfortunately, a complete phase shift analysis of several elastic scattering angular distributions measured on the maxima of these resonant structures shows that no spin assignment can be made. Therefore these intermediate structures appear to be spoiled by a more complex statistical resonance noise. At low incident energy, the Blair phase rule for oscillations in angular distributions is verified between the first $2^{+}$ target inelastic scattering and the elastic scattering.

NUCLEAR REACTIONS Measured elastic and inelastic excitation functions at $θ_{c . m .} = 180 °$ for ${}^{12}C$ + ${}^{24}{Mg}$ , $12 < E_{c . m .} < 27$ MeV. Deduced average width and autocorrelation and cross-correlation functions of the observed structure. Complete phase shift analysis of the elastic angular distributions measured at 24.8, 27.70, 28.60, 31.20, and 34.80 MeV ${}^{12}C$ incident energy; angular range 10° to 180° c.m. Inelastic scattering data at the same energies. Partial observation of the Blair phase rule.

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Alpha decay of neutron deficient polonium and bismuth isotopes

Direct $γ$ transitions in ${}^{12}C$ + ${}^{12}C$

Search for a giant resonance built on the 16.6-MeV state in ${}^{8}{Be}$

Nuclear axion decay

High-spin isomer in ${}^{211}{Rn}$ , and the shape of the yrast line

Structure in the reaction channels of ${}^{14}C$ + ${}^{14}C$

Erratum: Gamma-ray widths in ${}^{15}N$

Coulomb effects on charged particle exchange singularities

Approximate Coulomb correction to elastic $N - d$ scattering

Treiman-Yang criterion as a test of the pole approximation in the ${}^{9}{Be}$ ( ${}^{3}{He}$ , $α α$ ) ${}^{4}{He}$ reaction

Antisymmetrized elastic scattering and optical potential theory

Nuclear level densities from resonance averaged neutron capture $γ$ -ray spectra

Structure of ${}^{94}{Tc}$

Evidence for $J$ dependence in ${}^{60}{Ni}$ ( ${}^{3}{He}$ , $d$ ) ${}^{61}{Cu}$ cross sections

Energy dependence of the ${}^{208}{Pb}$ ( ${}^{4}{He}$ , $t$ ) and ( ${}^{4}{He}$ , ${}^{3}{He}$ ) reaction from 10 to 20 MeV/nucleon

Velocity dependence of transient hyperfine field at Pt ions rapidly recoiling through magnetized Fe

Level structure of ${}^{70}{Se}$

Folding-model description of elastic and inelastic scattering of ${}^{9}{Be}$ by ${}^{40, 44}{Ca}$ and ${}^{39}K$ at 40 MeV

Molecular resonance effects in heavy ion excitation functions

Intermediate structure and statistical fluctuations in the ${}^{12}C$ + ${}^{24}{Mg}$ system

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