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Small-angle correlations of pairs of nonidentical light charged particles produced in central collisions of heavy ions in the A= 100 mass region at a beam energy of 400 A· MeV are investigated with the FOPI detector system at GSI Darmstadt. The difference of longitudinal correlation functions with the relative velocity parallel and anti-parallel to the center-of-mass velocity of the pair in the central source frame is studied. This method allows extracting the apparent space-time differences of the emission of the charged particles. Comparing the correlations with results of a final-state interaction model delivers quantitative estimates of these asymmetries. Time delays as short as 1~fm/c or – alternatively – source radius differences of a few tenth fm are resolved. The strong collective expansion of the participant zone introduces not only an apparent reduction of the source radius but also a modification of the emission times. After correcting for both effects a complete sequence of the space-time emission of p, d, t, 3He, α particles is presented for the first time. [ABSTRACT FROM AUTHOR]

Models describing the resonant behaviour of heavy-ion reactions are briefly reviewed. Agreement between experimental data and calculated quantities has been surveyed. The application of these models to the scattering of α-particles from ligth nuclei is discussed. [ABSTRACT FROM AUTHOR]

Excitation function and angular distributions of theNi(S,S)Ni reaction were studied for incidentS energies ranging from 154 to 170 MeV. In spite of the current phenomenological models, predicting the presence of a resonant behaviour in this energy range, neither structures were observed in the elastic excitation function nor the presence of prominent single-wave states appeared in a statistical analysis of the angular distributions. [ABSTRACT FROM AUTHOR]

Resonances inC+C,C+O andO+O are described by a vibrating symmetric-top model. The calculated energy levels fit the experimental data rather well. Coefficients of the deformed and Morse potentials are calculated from the fit parameters. [ABSTRACT FROM AUTHOR]

Copyright of Il Nuovo Cimento: A is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Elastic and inelastic excitation functions have been measured for theS+Mg colliding system at incident energies from 110 to 137 MeV. Evidence has been found for a broad resonance ( Γ ⋍2 MeV) at E =130 MeV, in both the elastic and the inelastic channels. The excitation energy of this resonance in the composite systemNi corresponds very well to that observed in theSi+Si reaction. [ABSTRACT FROM AUTHOR]

Copyright of Il Nuovo Cimento: A is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Structures of non-statistical character, recently observed in 58Ni +46Ti elastic and 58Ni +62Ni elastic and inelastic excitation functions, produce damped oscillations in the cross section energy autocorrelation functions. The analysis of these damped oscillations in terms of S-matrix spin and parity decoherence indicates, as a possible interpretation, damping of the coherent rotational motion of the intermediate dinuclear system formed in the reaction. [ABSTRACT FROM AUTHOR]

Excitation functions and angular distributions ofNi+Ni andNi+Ni scattering at energies just above the Coulomb barrier have been measured around θ =90° in energy steps ΔE =0.25 MeV from E ⋍ 110 MeV to E ⋍ 120 MeV forNi+Ni and from E ⋍ 110 MeV to E ⋍ 118 MeV forNi+Ni. Evidence for structure of non-statistical character has been found in the angle-summed excitation functions; this evidence is corroborated by the analysis of the angular distributions. This is the first time that non-statistical structure in elastic and inelastic scattering is reported with high confidence level for this mass and excitation energy ranges. Attempts are presented to understand the nature of this structure, including the presence of intermediate dinuclear states and virtual states in a potential well. [ABSTRACT FROM AUTHOR]

The light charged particles emitted in theAr+Zn reaction performed at 14.6, 19.6 and 35 MeV/nucleon have been studied inclusively. The energy spectra have been analysed in terms of preequilibrium emission, moving source and coalescence models. A complete coherence between the present data and those obtained separately from heavy fragment studies is achieved. These data are consistent with the onset of projectile fragmentation between 20 and 35 MeV/nucleon correlated with the formation of a highly excited region of the nuclear system inducing light particle emission. The other sources of light particles can be interpreted as statistical and sequential decay of the quasi projectile. [ABSTRACT FROM AUTHOR]

The exciton model in its closed form and the Weisskopf-Ewing model have been consistently applied to neutron-induced reactions. The analysis has been performed for 12 nuclei in the range A=45-209. The primary particle-emission is considered to be governed by an admixture of precompound and compound-nucleus mechanisms, while all consecutive particles are considered to undergo pure compound-nucleus emission. The calculated primary-neutron spectra and excitation functions for ( n, p), ( n, 2 n) and ( n, 3 n) reactions at E=4-24 MeV have been compared with experimental data. The average best-fit values of the exciton-model free parameter K have been found to be ¯ K=700 MeV. Departures form this value appear to cancel out structure effects introduced into transition rates through the structure-sensitive single-particle level density. [ABSTRACT FROM AUTHOR]

The ( n, 2 n) cross sections for about 80 nuclei ranging from A=45 to 209 were calculated using the evaporation model. The calculation was performed for incident energies E which satisfy the condition U= E+ Q,2 n=6±1 MeV. For 11 nuclei in the above mass region, ( n, 2 n) excitation functions were calculated from threshold to 20 MeV. In all calculations a single set of input parameters was consistently used. The influence of the level-density parameter and neutron cross sections on the evaporation model was tested. All calculated results were compared with experimental data. The systematic discrepancy between experimental data and evaporation calculations leads to the necessity of introducing the preequilibrium emission mechanism. [ABSTRACT FROM AUTHOR]

Particles with strange quark content produced in the system 1.93 A·GeVNi onNi have been investigated at GSI Darmstadt with the FOPI detector system. The correlation of these produced particles was analyzed with respect to the reaction plane. Λ baryons exhibit a very pronounced sideward flow pattern which is qualitatively similar to the proton flow. However, the kaon ( K, K) flow patterns are significantly different from that of the protons, and their form may be useful to restrict theoretical models on the form of the kaon potential in the nuclear medium. [ABSTRACT FROM AUTHOR]

Excitation function and angular distributions of theNi(Ni,Ni)Ni elastic scattering have been measured at incidentNi energies from 220.0 to 230.0 MeV in steps of 0.5 MeV. Evidence of two structures was found in the excitation function; a statistical analysis suggests a possible nuclear cluster quasi-molecular nature for these structures. [ABSTRACT FROM AUTHOR]

An expression for determining the n/p ratio in heavy-ion reactions has been tested using recently published data. The agreement between the calculated and measured ratios is satisfactory. [ABSTRACT FROM AUTHOR]

Experimental inclusive proton spectra ofNi+Ni at 15.1 MeV/u have been decomposed using three moving sources associated with, respectively, equilibrium, deep-inelastic, and preequilibrium processes. For the last, a new expression, taking into account the anisotropy of preequilibrium particles in the source system, has been applied. The high-energy part of the obtained angle-integrated proton spectrum has been compared with predictions of the diabatic dissipation model. [ABSTRACT FROM AUTHOR]