Recent Articles

Photodisintegration of deuteron at low energies: Isolation of electric and magnetic contributions

M. L. Rustgi, A. Kassaee, and L. N. Pandey

Phys. Rev. C 35, 841 (1987) - Published 1 February, 1987

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Testing interacting boson model cores through particle-core coupling: Negative parity states in the odd-mass Tl and Au isotopes

P. B. Semmes, A. F. Barfield, B. R. Barrett, and J. L. Wood

Phys. Rev. C 35, 844 (1987) - Published 1 February, 1987

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Particle-core coupling calculations have been made for the $h_{9 / 2}$ bands in the odd-Tl isotopes (A=191–197) and the $h_{11 / 2}$ bands in the odd-Au isotopes (A=189–195). The even-mass Hg core descriptions were taken from previous proton-neutron interacting boson model calculations, and thus a comparison between the experimental and calculated level schemes for the Tl and Au isotopes can be interpreted as a test of the core description. A predicted transition from positive Q ${(2}^{+}$ ) near A=195 to negative Q ${(2}^{+}$ ) near A=191 is not borne out by the odd-A data. These results, combined with new proton-neutron interacting boson model calculations, indicate that the Hg isotopes are more U(5) than O(6) in character.

Number projection method

Kazunari Kaneko

Phys. Rev. C 35, 848 (1987) - Published 1 February, 1987

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Molecular states in excited spectra of light nuclei

Bo-jun Yang and Zheng Hwang

Phys. Rev. C 35, 851 (1987) - Published 1 February, 1987

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Erratum: Identification of collective flow by transverse-momentum analysis of emulsion data for Au+AgBr and Xe+AgBr [Phys. Rev. C 34, 1270 (1986)]

L. P. Csernai, P. Freier, J. Mevissen, H. Nguyen, and L. Waters

Phys. Rev. C 35, 854 (1987) - Published 1 February, 1987

Erratum: Doorway states and cross-section fluctuations in the ${}^{12}C ({}^{16}O, α)$ reaction

R. Bonetti, E. Fioretto, A. De Rosa, G. Inglima, and M. Sandoli

Phys. Rev. C 35, 854 (1987) - Published 1 February, 1987

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Selective sequential 2n decay of ${}^{14}C^{/ e m p h >}$ states populated by ${}^{13}C$ +n

D. A. Resler, R. O. Lane, and H. D. Knox

Phys. Rev. C 35, 855(R) (1987) - Published 1 February, 1987

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In the double-differential time-of-flight spectrum of emerging neutrons from neutrons incident on ${}^{13}C$ , a sharp substantital peak was observed whose energy remained constant as the incident neutron energy varied over at least 1.2 MeV. The results show that this peak is almost surely the secondary neutron group in the sequential 2n decay of levels in ${}^{14}C^{*}$ where the primary neutron decay (inelastic scattering) is to the ${(5 / 2)}^{-}$ (7.547 MeV) level in ${}^{13}C^{*}$ which then decays via a 3-MeV secondary neutron to the ground state of ${}^{12}C$ . This reaction appears to be very selective in that from 15.8 MeV to 18.4 MeV the states of ${}^{14}C^{*}$ do have substantial overlap with ${}^{13}C^{*}$ ( ${(5 / 2)}^{-}$ , 7.547 MeV) coupled to a neutron, whereas from 8 to 18.4 MeV they appear to have small or negligible overlap with the positive parity states of ${}^{13}C^{*}$ in this region.

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Signature dependence observed for M1 transitions between rotational levels based on an $f_{7 / 2}$ single-particle state in ${}^{163}{Dy}$

E. Minehara, M. Oshima, S. Kikuchi, T. Inamura, A. Hashizume, and H. Kumahora

Phys. Rev. C 35, 858(R) (1987) - Published 1 February, 1987

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The ground-state rotational band in ${}^{163}{Dy}$ has been investigated through multiple Coulomb excitation with beams of 160-MeV ${}^{35}{Cl}$ and 250-MeV ${}^{58}{Ni}$ . Excited states up to ${(27 / 2)}^{-}$ were established by measuring γ-γ coincidences and γ-ray angular distributions. Nuclear lifetimes for levels up to spin (23/2) have been determined by analysis of Doppler broadened γ-ray lineshapes. Considerable signature dependence was observed in M1 transition probabilities.

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Medium effects in the nuclear Landau-Vlassov transport theory

J. Cugnon, A. Lejeune, and P. Grangé

Phys. Rev. C 35, 861(R) (1987) - Published 1 February, 1987

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With the assumption that the Brueckner g matrix provides the suitable renormalization of the nucleon-nucleon interaction due to medium effects in the collision term of the nuclear Landau-Vlassov equation, we use the results of our Brueckner calculation for nuclear matter at finite temperature to evaluate the renormalization factor in a local and thermal approximation.

Phenomenological wave functions for the ground and 2.313 MeV states in sup14N

R. L. Huffman, J. Dubach, R. S. Hicks, and M. A. Plum

Phys. Rev. C 35, 1 (1987) - Published 1 January, 1987

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Transverse electron scattering form factors have been measured for elastic scattering and for the transition to the 2.313 MeV state in ${}^{14}N$ . Existing structure models could not simultaneously describe the two M1 form factors. Consequently, new phenomenological wave functions were determined by fitting the electron scattering results and other observables. For the 2.313 MeV transition, the new wave functions give smaller L=2 transition amplitudes than the earlier models. This reduction and the deduced value for the L=0 transition amplitude appear to be supported by the measurements of the ${}^{14}N$ (p,p’ $)^{14}$ N, ${}^{14}C$ (p,n $)^{14}$ N, and ${}^{14}{(γ}$ , $π^{+}$ $)^{14}$ C reactions. Although the L=0 transition amplitude is found to be relatively small, it is not small enough to give quantitative agreement with the severely retarded ${}^{14}C$ β-decay rate. The possibility that the vanishingly small β-decay matrix element is the result of destructive interference between the one-body matrix element and other terms is discussed.

Excitation of the high energy nuclear continuum in ${}^{208}{Pb}$ by 22 MeV/nucleon ${}^{17}O$ and ${}^{32}S$

F. E. Bertrand, R. O. Sayer, R. L. Auble, M. Beckerman, J. L. Blankenship, B. L. Burks, M. A. G. Fernandes, C. W. Glover, E. E. Gross, D. J. Horen, J. Gomez del Campo, D. Shapira, and H. P. Morsch

Phys. Rev. C 35, 111 (1987) - Published 1 January, 1987

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The ${}^{208}{Pb}$ high excitation continuum has been studied using inelastic scattering of 22 MeV/nucleon ${}^{17}O$ and ${}^{32}S$ . The spectra, taken with a magnetic spectrograph, show no evidence for peaks in the 30–100 MeV region of excitation in contrast to published results. The ${}^{17}O$ spectra are found to be remarkably similar to those from medium energy proton scattering.

Inclusive observables calculated with the nuclear random walk model: Application to the ${}^{40}{Ar}$ $+^{68}$ Zn reaction at 14.6 and 27.6 MeV/nucleon

A. J. Cole

Phys. Rev. C 35, 117 (1987) - Published 1 January, 1987

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A model for peripheral heavy ion reactions which includes, in a consistent formalism, both primary and secondary phases of the reaction mechanism is described. The model is based on a ‘‘nuclear random walk’’ in the projectile-like fragment mass which depends on the number of collisions between projectile and target nucleons along the classical trajectory of relative motion. Emphasis is placed on simple evaluation of experimental observables. An application to the ${}^{40}$ Ar $+^{68}$ Zn reaction, at 14.6 and 27.6 MeV/nucleon, is made and differences between model predictions and measurements, especially at the higher energy, are discussed.

Target and projectile excitation of ${}^{7}$ Li $+^{11}$ B, ${}^{13}C$

J. Cook, A. K. Abdallah, M. N. Stephens, and K. W. Kemper

Phys. Rev. C 35, 126 (1987) - Published 1 January, 1987

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Angular distributions are reported for the excitation of states in ${}^{11}B$ and ${}^{13}C$ and the first excited state in ${}^{7}{Li}$ at a ${}^{7}{Li}$ energy of 34 MeV. Both distorted-wave Born approximation and coupled channels calculations are reported for these reactions. The projectile excitation is reasonably well described with a collective rotational model for ${}^{7}{Li}$ . For the excitation of states in ${}^{11}B$ , strong-coupling rotational, weak-coupling particle-rotation, and microscopic models are used. Weak-coupling particle-rotation and microscopic models are used for excitation of states in ${}^{13}C$ . In general, for the target excitation there is good agreement between the various calculations and the experimental data.

Correlations between α particles and evaporation residues for the ${}^{14}C$ reaction at E $(^{14}$ N)=180 MeV

J. Gomez del Campo, D. E. DiGregorio, J. A. Biggerstaff, Y. D. Chan, D. C. Hensley, P. H. Stelson, D. Shapira, and M. E. Ortiz

Phys. Rev. C 35, 137 (1987) - Published 1 January, 1987

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Angular correlations between α particles and evaporation residues have been measured to study the equilibrium versus nonequilibrium effects on the fusion process. Measurements with α-particle detectors were carried out to extreme forward angles (4°) to maximize the sensitivity to nonequilibrium components. The results are consistent with complete fusion and equilibrium decay, in contrast with recent systematics that predict large amounts of incomplete fusion at this energy.

Nucleon-nucleon potential with quark degrees of freedom

M. Beyer and H. J. Weber

Phys. Rev. C 35, 14 (1987) - Published 1 January, 1987

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Nucleon-nucleon phase shifts for all partial waves, static properties, and electromagnetic form factors of the deuteron are calculated from an NN potential, which has a mesonic sector with only two adjusted parameters and is supplemented by a phenomenological six-quark core potential with a P-matrix-type parametrization. NN phase shifts constrain the six-quark core radius within 1 ≤b≤1.2 fm. The deuteron’s magnetic structure function B agrees with the data only for b=1 fm. The six-quark core probability is about 2.3%.

Heavy ion collisions and anisotropic hydrodynamics

I. Lovas, G. Wolf, and N. L. Balazs

Phys. Rev. C 35, 141 (1987) - Published 1 January, 1987

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The study of the isotropization of momentum is important in heavy ion collisions. To do this we construct a generalized hydrodynamical equation system, in which the anisotropy of the momentum distribution is added as a new variable. These equations are derived from the moment equations of the relativistic Boltzmann equation where the closure of the set is achieved by assuming a particular class of initial conditions. The equations are then explicitly solved for two uniform interpenetrating hadron streams. The collision cross sections are the bare hadron cross sections; the presence of the other hadrons can be simulated by the use of a density- and energy-density-dependent temperature and mass, taken over from self-consistent calculations. The results are compared with other theoretical results. We find that the isotropization occurs sufficiently rapidly for medium energy head-on collisions to reach local thermal equilibrium.

Linear momentum and angular momentum transfer in the reactions of ${}^{16}O$ with ${}^{154}{Sm}$

M. N. Namboodiri, R. K. Choudhury, L. Adler, J. D. Bronson, D. Fabris, U. Garg, P. L. Gonthier, K. Hagel, D. R. Haenni, Y. W. Lui, Z. Majka, G. Mouchaty, T. Murakami, J. B. Natowitz, G. Nebbia, R. P. Schmitt, S. Simon, J. P. Sullivan, and D. H. Youngblood

Phys. Rev. C 35, 149 (1987) - Published 1 January, 1987

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From coincidence measurements between projectile-like fragments or heavy residues and their associated γ rays, the angular momentum transfers for a variety of incomplete fusion reactions of 180 and 310 MeV ${}^{16}O$ with ${}^{154}{Sm}$ have been derived. At the higher energy, the correlation between angular momentum transfer and linear momentum transfer has been obtained over the entire range of linear momentum transfer. A comparison of the data with calculations of both the sum-rule and geometric overlap models indicates that each makes reasonable predictions of the observed trend even though the assumptions of the models are quite different, and very different initial partial waves are predicted to contribute to particular reaction channels. This results primarily from prescriptions relating fractional mass transfer to fractional angular momentum transfer. The reconstruction of the initial partial wave distributions from correlated measurements of linear momentum and angular momentum transfers is addressed. Comparisons are also made with more recent model calculations which focus on nucleon-nucleon scattering as the mechanism of momentum transfer.

Complete and incomplete fusion in ${}^{20}{Nb}$ reactions

D. J. Parker, J. J. Hogan, and J. Asher

Phys. Rev. C 35, 161 (1987) - Published 1 January, 1987

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Cross sections for production of radioactive product residues from reactions of ${}^{20}{Ne}$ on ${}^{93}{Nb}$ have been measured at incident energies of 106 and 148 MeV. Detailed differential recoil range distributions have been measured for many of these products, and show evidence of several incomplete fusion processes in addition to complete fusion. The inclusive spectra of emitted protons, alpha particles, and projectilelike fragments have been measured at the same incident energies, and show components consistent with some form of projectile breakup. These breakup fragments are hypothesized to be the spectator fragments arising from incomplete fusion. Whereas the recoil range distribution data cannot be accounted for by statistical model calculations assuming only complete fusion, inclusion of the various incomplete fusion processes on the basis of the above hypothesis does reproduce the data. There is also an indication of direct transfer processes contributing to formation of near-target products.

Solving coupled equations by iteration for heavy-ion multiple Coulomb-nuclear excitation

L. D. Tolsma

Phys. Rev. C 35, 177 (1987) - Published 1 January, 1987

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To describe quantum mechanically multiple Coulomb-nuclear excitation in heavy-ion reactions, the set of coupled differential equations of the partial-wave radial solutions is rewritten in integral form. Decomposing these solutions into two basis functions, the corresponding amplitudes of these functions satisfy a set of coupled integral equations. Expressing the basis functions in terms of appropriately chosen piecewise analytic reference solutions, the integrals appearing in this set can be evaluated analytically. The coupled set of amplitude equations is solved iteratively. The efficiency of two iteration methods, the inward-outward and the sequential one, has been investigated for test cases dealing with multiple Coulomb and nuclear excitation of ${}^{238}U$ by 286 MeV ${}^{40}{Ar}$ and 718 MeV ${}^{84}{Kr}$ up to high spin states of the ground-state rotational band. Padé approximants to the S-matrix elements were also included in both of the iteration methods. It turns out that the inward-outward iteration method converges much faster than the sequential one. In many cases, the inward-outward method does not need Padé acceleration at all, while the sequential method does. It happens that convergent cases in the inward-outward method diverge in the sequential method aided by Padé approximants. Numerical studies of the excitation probabilities as a function of the scattering angle for the aforementioned heavy-ion reactions show that the probability functions of the members of the ground-state rotational band satisfy a general rule at near-grazing angles, previously formulated for the excitation probability as a function of the energy near the Coulomb barrier for backward scattering from a deformed rotor.

Production and decay of highly excited nuclear systems formed in ${}^{84}{Kr}$ $+^{12}$ C and ${}^{27}{Al}$ collisions at 35 MeV/nucleon

F. Auger, B. Berthier, A. Cunsolo, A. Foti, W. Mittig, J. M. Pascaud, E. Plagnol, J. Québert, and J. P. Wieleczko

Phys. Rev. C 35, 190 (1987) - Published 1 January, 1987

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Masses, atomic numbers, and energies of heavy (M≥15 nucleons) particles emitted in the reactions induced by ${}^{84}{Kr}$ on ${}^{12}C$ and ${}^{27}{Al}$ at 35 MeV/nucleon have been measured by means of two time-of-flight silicon counter telescopes. Experimental results from single and coincidence measurements are presented and discussed in the framework of the statistical sequential decay model following complete and incomplete fusion in the entrance channel.

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Photodisintegration of deuteron at low energies: Isolation of electric and magnetic contributions

Testing interacting boson model cores through particle-core coupling: Negative parity states in the odd-mass Tl and Au isotopes

Number projection method

Molecular states in excited spectra of light nuclei

Erratum: Identification of collective flow by transverse-momentum analysis of emulsion data for Au+AgBr and Xe+AgBr [Phys. Rev. C 34, 1270 (1986)]

Erratum: Doorway states and cross-section fluctuations in the ${}^{12}C ({}^{16}O, α)$ reaction

Selective sequential 2n decay of ${}^{14}C^{/ e m p h >}$ states populated by ${}^{13}C$ +n

Signature dependence observed for M1 transitions between rotational levels based on an $f_{7 / 2}$ single-particle state in ${}^{163}{Dy}$

Medium effects in the nuclear Landau-Vlassov transport theory

Phenomenological wave functions for the ground and 2.313 MeV states in sup14N

Excitation of the high energy nuclear continuum in ${}^{208}{Pb}$ by 22 MeV/nucleon ${}^{17}O$ and ${}^{32}S$

Inclusive observables calculated with the nuclear random walk model: Application to the ${}^{40}{Ar}$ $+^{68}$ Zn reaction at 14.6 and 27.6 MeV/nucleon

Target and projectile excitation of ${}^{7}$ Li $+^{11}$ B, ${}^{13}C$

Correlations between α particles and evaporation residues for the ${}^{14}C$ reaction at E $(^{14}$ N)=180 MeV

Nucleon-nucleon potential with quark degrees of freedom

Heavy ion collisions and anisotropic hydrodynamics

Linear momentum and angular momentum transfer in the reactions of ${}^{16}O$ with ${}^{154}{Sm}$

Complete and incomplete fusion in ${}^{20}{Nb}$ reactions

Solving coupled equations by iteration for heavy-ion multiple Coulomb-nuclear excitation

Production and decay of highly excited nuclear systems formed in ${}^{84}{Kr}$ $+^{12}$ C and ${}^{27}{Al}$ collisions at 35 MeV/nucleon

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