A possible mechanism in heavy ion induced reactions: ?Fast fission process?

Borderie, B.; Berlanger, Michel; Gardès, D.; Hanappe, F.; Nowicki, Ł.; Péter, J.; Tamain, B.; Agarwal, S.; Girard, J.; Grégoire, C.; Matuszek, J.; Ngô, Christian

doi:10.1007/bf01443944

Cited by 111 publications

(29 citation statements)

References 14 publications

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“…Although the error bars are large, this could be an indication of a limitation of the fusion cross section when the energy grows up. A similar observation has been made on the Mg + Cu [17] and Mg + Ta [15] systems above 10 MeV/u. The Bass model [18] introduces such a limiting value.…”

Section: Fission Cross-sectionsupporting

confidence: 76%

“…This value is higher than the l value for which the fission barrier vanishes fibs = 0 ~ 74 in the rotating liquid drop model) [14]. Therefore, it can be deduced that the fission cross section measured here is the sum of the cross section for fission of a totally equilibrated compound nucleus and of that for fast fission [15]; in the latter process, the characteristics of the symmetric fragmentation are determined at the turning point rather than at the equilibrium saddlepoint. The cross section value measured here is slightly lower than the one obtained at 172 MeV on the same system by Duek et al [16] (1,570 mb).…”

Section: Fission Cross-sectionmentioning

confidence: 91%

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Correlations between fission fragments and light charged-particles in the reaction20Ne+197Au at 13 MeV/nucleon

et al. 1982

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Energy of light charged-particles has been measured in coincidence with one or two fission fragments in the reaction Z°Ne+ 197Au at a bombarding energy of 13 MeV/u. The fission cross section was found equal to 1,340 + 260 rob. Assuming that it represents the totality of the fusion cross section, the critical value l c is deduced equal to 93 _+ 9 h, higher than /By=o--74 in the rotating liquid drop model. The main emission source for protons and alpha particles seems to be a thermally equilibrated composite system. The competition between fission and charged particle emission is unexpected in the frame of the statistical treatment. A high energy component is observed in the forward direction. These results correspond to the first step of a study programme on the evolution of nucleus-nucleus collisions between 10 and 100 MeV per nucleon.

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Section: Fission Cross-sectionsupporting

confidence: 76%

Section: Fission Cross-sectionmentioning

confidence: 91%

Correlations between fission fragments and light charged-particles in the reaction20Ne+197Au at 13 MeV/nucleon

et al. 1982

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“…Unexpected mass-and angular distributions of fission-like products in reactions involving high angular momenta or high fissilities were observed and discussed in e.g. [23][24][25][26].…”

Section: Introductionmentioning

confidence: 93%

Investigation of the fusion of heavy nearly symmetric systems

Quint

Reisdorf

Schmidt

et al. 1993

Z. Physik A - Hadrons and Nuclei

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Abstract. Excitation functions in the vicinity of theCoulomb barrier have been measured for the formation of evaporation residues in l~176 fusion reactions with 9~ 92,96,98, lOOMo ' 104Ru and l~~ as well as for the system 96Zr + 96Zr. From these data the fusion probability in central collisions was extracted covering a range of 4 orders of magnitude. At the fusion barriers expected from systematics we find that the fusion probability is suppressed by one to three orders of magnitude. It is rising very gradually at higher energies and reaches for the heaviest systems saturation only at energies as high as 30 MeV above the barrier. The observed hindrance of the fusion process increases roughly with the growing Coulomb repulsion between the collision partners, but there is also a distinct influence of their individual nuclear structure. The data are compared to the extra-push model, the surface-friction model and the diabatic fusion model. A parameterisation of the extra-push energy and its fluctuation in terms of a macroscopic quantity like the Coulomb repulsion combined with a microscopic quantity characterizing the nuclear structure is proposed. As a byproduct of this work a new alpha emitter, 191po, could be identi-+6 fled. Its half-life is (15.5_z s) ms, the alpha energy is (7314 _ 20) keV.

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“…It has been suggested that a new dissipative mechanism between the normal compound nucleus reactions and the deeply inelastic reactions is responsible for this additional cross section [3,[10][11][12][13]. The picture associated with this new mechanism is that partial waves 1 larger than /B~=o but smaller than lerlt form a dinuclear system living long enough to equilibrate the drift of the mass asymmetry towards symmetry.…”

Section: Introductionmentioning

confidence: 97%

Alpha emission in coincidence with fission-like fragments from Cl+Ag reactions at 10 MeV/n

Schad

Fan

et al. 1984

Z Physik A

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Energy and angular correlations between alpha particles and fission-like fragments in the reaction of asCI+Ag at 10MeV/n have been measured. The coincident yield is dominated by two mechanisms: sequential emission from both fragments (M~=0.137 _+0.014) and alpha emission from the composite system prior to scission (M,=0.124 _+0.012). The observation of nuclear shadowing for sequential emission from the fragments allowed us to estimate the "lifetime" of the 218 MeV excited 143Gd composite system as (1-3)x10-2~It is argued that this rather long time reflects the slow evolution in shape of the composite system and might be termed "sticking time," since statistical-model lifetimes are typically an order of magnitude shorter. Observed also are small contributions of nonequilibrium emission in the forward direction (M~=0.005 _+0.001) and a component displaying the characteristics of emission from the neck (M s = 0.010 + 0.002).

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A possible mechanism in heavy ion induced reactions: ?Fast fission process?

Cited by 111 publications

References 14 publications

Correlations between fission fragments and light charged-particles in the reaction20Ne+197Au at 13 MeV/nucleon

Correlations between fission fragments and light charged-particles in the reaction20Ne+197Au at 13 MeV/nucleon

Investigation of the fusion of heavy nearly symmetric systems

Alpha emission in coincidence with fission-like fragments from Cl+Ag reactions at 10 MeV/n

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