Spin distribution of the compound nucleus formed by 16O+154Sm

Gil, S. ; Vandenbosch, R. ; Charlop, A. ; Garca, A. ; Leach, D. D. ; Luke, S. J. ; Kailas, S. (1991) Spin distribution of the compound nucleus formed by 16O+154Sm Physical Review C, 43 (2). pp. 701-708. ISSN 0556-2813

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Official URL: http://prc.aps.org/abstract/PRC/v43/i2/p701_1

Related URL: http://dx.doi.org/10.1103/PhysRevC.43.701


Gamma-ray multiplicities for the 16O+154Sm system have been determined using two different coincidence techniques. Fusion events are tagged either by observation of low-lying gamma transitions in the evaporation residues or by direct detection of the residues exploiting an electrostatic deflector and time-of-flight identification. The gamma-ray tagging measurements have been made with higher sensitivity than previously, allowing us to include the contribution of the 3n channel. The contribution of this channel modifies the conclusions made before in regard to the spin distribution of the compound nucleus produced at near-barrier energies. The procedure for conversion of gamma-ray multiplicities to mean spin values has been calibrated by measuring gamma-ray multiplicities and fusion cross sections for the 4He+166Er and 3He+167Er reactions that lead to the same compound nucleus as 16O+154Sm, at bombarding energies that span the same region of excitation energies and spin. The use of an electrostatic deflector enables an inclusive tag on all evaporation residues, and has sufficient sensitivity to enable measurements at a lower energy than is possible with gamma-ray tagging techniques. The energy dependence of the mean spin deduced from gamma-ray multiplicity measurements is in qualitative agreement with model calculations which include the effects of the static and dynamical deformations of the target nucleus. There is, however, a tendency for the calculations to underestimate somewhat the mean spin near and below the barrier.

Item Type:Article
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ID Code:15647
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