Evaporation residues from heavy (Z=90?93) compound nuclei at excitation energies of Ex ? (75?110) MeV

Heßberger, F. P.; Ninov, V.; Ackermann, D.

doi:10.1007/bf01291529

Cited by 7 publications

(1 citation statement)

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“…Further details on the experimental set-up as well as data aquisition and analysis are given in [13,19]. Typical a-spectra, observed in our experiments, are shown in Fig.…”

Section: H Experimentsmentioning

confidence: 98%

?Slow? residues observed in the reaction20Ne+208Pb at E/A=8.6, 11.4 and 15.0 MeV/u

Heßberger

Ninov

Hofmann

et al. 1994

Z. Physik A - Hadrons and Nuclei

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Abstract. Velocity distributions of heavy residues ARes>Atar, ZRe s>Zta r identified by means of c~ spectroscopy, have been investigated at the velocity filter SHIP in reactions 2~ +2~ at projectile energies E/ A=8.6, 11.4 and 15.0MeV/u. Besides products from complete or nearly complete fusion, characterized by velocity distributions peaking at V/VcN~0.8-1.O, heavy residues with mean velocities of about half of the compound nucleus velocity were observed. The Z-distribution of this component was found to peak at Z = 87. It is interpreted as residues from fusion of target nuclei with projectile fragments produced by nearly symmetric break-up. The experimental results were compared with predictions of theoretical models: cross sections for incomplete fusion were calculated using the sum-rule model of Wilcynski et al., while residue cross sections were calculated using the evaporation code HIVAP. A fair agreement between experimental and calculated mass distributions of heavy residues and transferred projectile fragments is achieved if an energy dissipation of -~ 23 % (at E/A = 8.6 MeV/u) and ~ 8% (at E/A = 11.4 MeV/u) of the incident projectile energy is introduced. The observed peak of the Z-distribution at Z = 87 is predominantly effected due to a higher fission probability of products with Z>87 during the deexcitation process and experimental limitations in the identification of products with Z < 86 by means of ~ spectroscopy, which cause a decrease of the observed production rates towards lower Z.

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“…Further details on the experimental set-up as well as data aquisition and analysis are given in [13,19]. Typical a-spectra, observed in our experiments, are shown in Fig.…”

Section: H Experimentsmentioning

confidence: 98%