skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Limitation of heavy-ion fusion: Fusion of aligned /sup 23/Na with /sup 23/Na

Abstract

The excitation function for fusion of /sup 23/Na with /sup 23/Na was measured in the energy range 40 less than or equal to E/sub c.m./less than or equal to 88.5 MeV. Additionally the tensor analyzing power T/sub 20/ was determined to be T/sub 20/ = -0.0060 +- 0.0125 at E/sub c.m./ = 85 MeV. The results are discussed in terms of an entrance-channel versus a compound-nucleus model for the observed limitation of fusion. A typical entrance-channel model, the surface-friction model, which is able to describe all fusion excitation functions leading to /sup 46/Ti, fails to reproduce the observed value of T/sub 20/. The data are consistent, on the other hand, with the compound-nucleus interpretation.

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Philipps-Universitaet, Fachbereich Physik, 3550 Marburg, West Germany
OSTI Identifier:
5080586
Resource Type:
Journal Article
Resource Relation:
Journal Name: Phys. Rev. Lett.; (United States); Journal Volume: 57:7
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; SODIUM 23 REACTIONS; COMPOUND-NUCLEUS REACTIONS; HEAVY ION FUSION REACTIONS; SODIUM 23 TARGET; TITANIUM 46; YRAST STATES; ANALYZING POWER; ANGULAR DISTRIBUTION; ANGULAR MOMENTUM; CROSS SECTIONS; EXCITATION FUNCTIONS; MEV RANGE 10-100; MOMENT OF INERTIA; STATISTICAL MODELS; TENSOR FORCES; TIME-OF-FLIGHT SPECTROMETERS; CHARGED-PARTICLE REACTIONS; DISTRIBUTION; ENERGY LEVELS; ENERGY RANGE; EVEN-EVEN NUCLEI; FUNCTIONS; HEAVY ION REACTIONS; INTERMEDIATE MASS NUCLEI; ISOTOPES; MATHEMATICAL MODELS; MEASURING INSTRUMENTS; MEV RANGE; NUCLEAR REACTIONS; NUCLEI; SPECTROMETERS; STABLE ISOTOPES; TARGETS; TITANIUM ISOTOPES; 651425* - Nuclear Properties & Reactions, A=20-38, Experimental- Nuclear Reactions & Scattering- (-1987); 651523 - Nuclear Properties & Reactions, A=39-58, Experimental- Energy Levels & Transitions- (-1987)

Citation Formats

Blatt, K., Becker, K., Heck, B., Jaensch, H., Leucker, H., Fick, D., Chacekaplar, R., Butsch, R., Kraemer, D., and Moebius, K.h. Limitation of heavy-ion fusion: Fusion of aligned /sup 23/Na with /sup 23/Na. United States: N. p., 1986. Web. doi:10.1103/PhysRevLett.57.819.
Blatt, K., Becker, K., Heck, B., Jaensch, H., Leucker, H., Fick, D., Chacekaplar, R., Butsch, R., Kraemer, D., & Moebius, K.h. Limitation of heavy-ion fusion: Fusion of aligned /sup 23/Na with /sup 23/Na. United States. doi:10.1103/PhysRevLett.57.819.
Blatt, K., Becker, K., Heck, B., Jaensch, H., Leucker, H., Fick, D., Chacekaplar, R., Butsch, R., Kraemer, D., and Moebius, K.h. Mon . "Limitation of heavy-ion fusion: Fusion of aligned /sup 23/Na with /sup 23/Na". United States. doi:10.1103/PhysRevLett.57.819.
@article{osti_5080586,
title = {Limitation of heavy-ion fusion: Fusion of aligned /sup 23/Na with /sup 23/Na},
author = {Blatt, K. and Becker, K. and Heck, B. and Jaensch, H. and Leucker, H. and Fick, D. and Chacekaplar, R. and Butsch, R. and Kraemer, D. and Moebius, K.h.},
abstractNote = {The excitation function for fusion of /sup 23/Na with /sup 23/Na was measured in the energy range 40 less than or equal to E/sub c.m./less than or equal to 88.5 MeV. Additionally the tensor analyzing power T/sub 20/ was determined to be T/sub 20/ = -0.0060 +- 0.0125 at E/sub c.m./ = 85 MeV. The results are discussed in terms of an entrance-channel versus a compound-nucleus model for the observed limitation of fusion. A typical entrance-channel model, the surface-friction model, which is able to describe all fusion excitation functions leading to /sup 46/Ti, fails to reproduce the observed value of T/sub 20/. The data are consistent, on the other hand, with the compound-nucleus interpretation.},
doi = {10.1103/PhysRevLett.57.819},
journal = {Phys. Rev. Lett.; (United States)},
number = ,
volume = 57:7,
place = {United States},
year = {Mon Aug 18 00:00:00 EDT 1986},
month = {Mon Aug 18 00:00:00 EDT 1986}
}
  • Using aligned /sup 23/Na beams, fusion cross sections sigma/sup fus/ and second-rank tensor analyzing powers for fusion T/sub 20//sup fus/ have been measured at energies near and below the fusion barrier for /sup 23/Na+ /sup 48/Ti and for /sup 23/Na+ /sup 206/Pb. At sub-barrier energies, large, nearly maximal, values of T/sub 20//sup fus/ occur, especially for fusion with the heavy target /sup 206/Pb. This reflects the strong influence of the spectroscopic deformation of the projectile on the fusion process at energies below the barrier. However, within a quantum-mechanical coupled-channels calculation this degree of freedom is not enough to describe bothmore » the fusion cross section and the second-rank tensor analyzing power for fusion in the energy regime below the fusion barrier. It is shown that the coupling of the fusion channel to inelastic excitations of the projectile and the target can describe the magnitude and energy dependence of T/sub 20//sup fus/ for both heavy ion systems, but fails to reproduce the ''sub-barrier enhancement'' of the fusion cross section for both systems.« less
  • Excitation functions for the yields of residual nuclei from the /sup 7/Li+/sup 16/O and /sup 9/Be+/sup 14/N reactions have been measured for /sup 7/Li and /sup 14/N laboratory bombarding energies of 12 to 34 MeV and 15 to 63 MeV, respectively. Beginning at Coulomb barrier energies, we find that the total fusion cross section diverges from the total reaction cross section obtained from optical model fits to elastic scattering data. This indicates that the process responsible for fusion cross section limitations in this mass region begins near the Coulomb barrier and becomes progressively more important as the bombarding energy ismore » increased. Comparison of the critical angular momenta deduced from the total fusion cross sections for these and two previously investigated entrance channels which form the /sup 23/Na compound nucleus, /sup 11/B+/sup 12/C and /sup 10/B+/sup 13/C, rules out a compound nucleus limitation at these energies. A systematic study of fusion cross sections in this mass and energy region, together with the results of a previous study of the light particles produced in the /sup 11/B+/sup 12/C and /sup 10/B+/sup 13/C reactions, suggests that competition for entrance channel flux by reactions producing light particles with projectilelike velocities is primarily responsible for the fusion cross section limitations.« less
  • Fusion cross sections and second-rank-tensor analyzing powers for fusion have been measured at energies around the fusion barrier for /sup 23/Na+ /sup 48/Ti, /sup 206/Pb with polarized (aligned) projectiles. The data are compared with results from coupled-channels calculations. The energy dependence of the second-rank-tensor analyzing power for fusion is well described for both systems if we take into account coupling to excited states of projectile and target. The same calculations still underpredict the cross section for fusion at subbarrier energies.