Emission of complex fragments from highly excited systems produced in 93Nb+9Be and 27Al reactions at and 30.3 MeV

Charity, R. J.; Bowman, D. R.; Liu, Z.H.; McDonald, R. J.; McMahan, M. A.; Wozniak, G.J.; Moretto, L.G.; Bradley, S. T.; Kehoe, W. L.; Mignerey, A. C.

doi:10.1016/0375-9474(88)90422-8

Cited by 96 publications

(31 citation statements)

References 27 publications

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“…The broadening of the angular distributions with decreasing Z due to the emission of more light particles is fairly well reproduced by the calculations except for the experimental Z= 19 angular distribution which appears to extend to larger angles. However this behavior is less visible than at higher excitation energy [21] for which the emission of complex fragments [38,39,54,55] has been shown to be more competitive. Fig.…”

Section: Angular Distributionsmentioning

confidence: 98%

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Competition between the fusion-fission and deep-inelastic orbiting mechanisms in the35Cl +12C reaction

Beck

Djerroud

Haas

et al. 1992

Z. Physik A - Hadrons and Nuclei

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The binary decay properties of the 477 nucleus, produced in the 35C1 + 12C reaction, have been investigated at the 35C1 bombarding energies Elab=180 and 200 MeV by means of a kinematical coincidence technique. Binary reaction products show full energy equilibration and a characteristic 1/sin(0om ) angular distribution. The elemental distribution of the fully-damped products is asymmetric, similar to what has previously been observed in the decay of the 56Ni nucleus. Comparison with theoretical model predictions suggests the occurrence of a fusion-fission rather than orbiting process. Moreover the calculations performed using the Extended HauserFeshbach Method reproduce well the experimental fission yields~ A general discussion of orbiting and fusionfission experimental data of light heavy-ion systems is presented in the framework of the calculated number of available open channels for these systems.

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Section: Angular Distributionsmentioning

confidence: 98%

“…Mean velocities of the binary fragments have been extracted from the measured energies and from the Zvalues by assuming the empirical mass formula proposed by Charity et al [55]: …”

Section: Properties Of the Binary Productsmentioning

confidence: 99%

Competition between the fusion-fission and deep-inelastic orbiting mechanisms in the35Cl +12C reaction

Beck

Djerroud

Haas

et al. 1992

Z. Physik A - Hadrons and Nuclei

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“…The better agreement predicted by GEMINI appears to result from the empirical radius parametrization (2 frn separation between partners), which reproduces the low-energy binary-decay systematics [4,29]. This parametrization may mimic the shape polarization effects mentioned above which decrease the average Coulomb energies.…”

Section: Velocity and Angular Distributionsmentioning

confidence: 75%

“…A widely used technique for isolating the sources contributing to fragment emission is to plot the cross section in velocity space for a given atomic number as d o'/dv~~dv~ [5,6,19,29,46,52]. This is a particularly powerful technique when a global observable such as the charged-particle multiplicity or the total detec'ted charge is used as an event selector.…”

Section: Velocity and Angular Distributionsmentioning

confidence: 99%

“…12 (top) depict the angular distribution of C fragments in this kame as a difFerential multiplicity, namely, fragments per event per radian. The yield rises slowly with angle be- Assuming that all of the &agments emitted forward of 90 degrees arise from fully relaxed statistical emission, the forward-backward ratio of the di8'erential cross section can be used to estimate the degree of equilibration of the angular degrees of freedom [29]. Such a decomposition for angles of 30' -150 gives an equilibrium &action of -78% for Nc & 14 events.…”

Section: Velocity and Angular Distributionsmentioning

confidence: 99%

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Space-time characteristics of fragment emission in theE/A=30 MeVXe129+
Bowman¹,
Colonna²,
Friedman³
et al. 1995
Phys. Rev. C
25
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4
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Intermediate-mass-fragment emission has been studied in central E/A = 30 MeV Xe + " 'Cu reactions. The measured fragment multiplicities, reduced-velocity correlation functions, and emission velocities have been compared with schematic three-body trajectory calculations and with three statistical models with input based upon a dynamical BNV code. The statistical models which include expansion either explicitly or implicitly are able to generate a sufBcient number of fragments. The three-body trajectory calculations indicate a mean emission time of = 200 fm/c, consistent with sequential decay. Dynamical expanding-emitting source calculations predict a similar time scale for fragment emission and give satisfactory agreement with the experimental correlation functions if the experimental angular distributions are incorporated into the model. The Berlin multifragmentation model gives good agreement with the experimental charge distributions, and, depending upon the choice of radius parameter, can provide agreement with either the correlation functions or the fragment emission velocities, but not with both simultaneously. Although an overall good agreement is obtained in the statistical model comparisons, even in the most violent collisions the angular distributions and fragment emission velocities are incompatible with completely equilibrated decay from a single source. PACS uumber(s): 25.70.Pq I. INTR.C)DU CTI(3N Studies of IMF (intermediate mass fragment, 3 & Z ( 20) emission [1] have provided a wealth of information about the space-time extent of excited nuclear systems. At high bombarding energy, E/A ) 100 MeV, the fragments appear to be emitted on the very short time scale implied by a prompt multi&agment disassembly of heated and expanded nuclear systems [2,3]. At low bombarding energy, E/A & 20 MeV, standard compound nucleus decay accounts for much of the fragment yield following either complete or incomplete fusion reactions [4 -6]. To gain a systematic understanding of the interaction between complex nuclei it is important to characterize the intermediate bombarding energy regime, where the fragment emission time scale changes from sequential to simultaneous [7,8], and nuclear expansion begins to occur [9,10].Observables which have been employed to infer the spatial and temporal extensions of fragmentation sources are &agment yields, &agment-&agment reduced-velocity correlation functions, and emission velocities of emitted fragments.The IMF yields calculated with statistical emission models are strongly dependent on the density of the emitting system [11 -14]. Comparisons of experimental data with model predictions have shown that nuclear expansion is needed to reproduce the observed fragment multiplicities and charge distributions, even at bombarding energies as low as E/A = 35 MeV [13]. The fragment emission time scale, as determined from fragmentfragment correlations, is a direct measure of the spacetime extent of the source [2,3,7,8, 15 -26]. The fragment emission velocities are sensitive to an expansion ...

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129Xe-Induced Peripheral Reactions at E/A = 50 MeV

Madani

Mignerey

Russ

et al. 1996

Advances in Nuclear Dynamics

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Emission of complex fragments from highly excited systems produced in 93Nb+9Be and 27Al reactions at and 30.3 MeV

Cited by 96 publications

References 27 publications

Competition between the fusion-fission and deep-inelastic orbiting mechanisms in the35Cl +12C reaction

Competition between the fusion-fission and deep-inelastic orbiting mechanisms in the35Cl +12C reaction

Space-time characteristics of fragment emission in theE/A=30 MeVXe129+
Bowman¹,
Colonna²,
Friedman³
et al. 1995
Phys. Rev. C
25
0
4
0
View full text Add to dashboard Cite

129Xe-Induced Peripheral Reactions at E/A = 50 MeV

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Emission of complex fragments from highly excited systems produced in 93Nb+9Be and 27Al reactions at and 30.3 MeV

Cited by 96 publications

References 27 publications

Competition between the fusion-fission and deep-inelastic orbiting mechanisms in the35Cl +12C reaction

Competition between the fusion-fission and deep-inelastic orbiting mechanisms in the35Cl +12C reaction

Space-time characteristics of fragment emission in theE/A=30 MeVXe129+Bowman1, Colonna2, Friedman3 et al. 1995Phys. Rev. C25040View full textAdd to dashboardCite

129Xe-Induced Peripheral Reactions at E/A = 50 MeV

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Space-time characteristics of fragment emission in theE/A=30 MeVXe129+
Bowman¹,
Colonna²,
Friedman³
et al. 1995
Phys. Rev. C
25
0
4
0
View full text Add to dashboard Cite