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  • 1
    Electronic Resource
    Electronic Resource
    Inclusive and exclusive preequilibrium spectra in a model of independently interacting excitons (1987)
    Springer
    The European physical journal 328 (1987), S. 333-350 
    Details
    ISSN: 1434-601X
    Keywords: 24.60.Dr ; 24.60.Gv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Starting from a previous ansatz ofindependently interacting excitons the more refined model INCLUSIVE INDEX is developed yieldinginclusive preequilibrium proton and neutron spectra. It is shown that three stages are sufficient to describe single- and multi-nucleon emission to all orders of practical importance. By use of recurrence relations the loss of particles and energy due to emission from previous stages is fully accounted for. In order to predict the population of specific residual nuclei the precompound process is reformulated in terms ofexclusive emission spectra. This intricate statistical problem is solved in the EXCLUSIVE INDEX model by algorithms representing the average probability for a specified number of particles not to be emitted but to reach the next stage of nuclear relaxation. Differential excitation probabilities can be calculated for those six nuclei which are populated by the emission of none, one, or two preequilibrium nucleons in two stages via alltogether 15 principal paths. Typical features of the INCLUSIVE and EXCLUSIVE INDEX model are discussed. The strength of one- and two-nucleon emission is compared with HYBRID model predictions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01290502
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Analysis of inclusive nucleon spectra fromp- andα-induced reactions in the frame of the INDEX model, and implications for stopped π−-induced reactions (1987)
    Springer
    The European physical journal 328 (1987), S. 445-453 
    Details
    ISSN: 1434-601X
    Keywords: 24.60.Dr ; 24.60.Gv ; 25.80.Ls
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The previously published INDEX model is tested for nucleon spectra fromp- andα-induced reactions. The results of two alternative versions, the INCLUSIVE INDEX model and the EXCLUSIVE INDEX model, quite well agree with the data. It is found that in the INCLUSIVE INDEX model three preequilibrium stages are sufficient to describe single- and multi-nucleon emission. The model provides an useful first order estimate of the influence of the finite Fermi energy on particle spectra. This effect is very strong for nucleon induced reactions while forα-induced reactions it can be neglected. The deduced mean-free-path multiplier corroborates the long stated discrepancy between models in which excitons interact independently or not. Using preequilibrium parameters similar to those found for nucleon induced reactions the important branching ratio of contributingnp andpp pairs in stoppedπ −-absorption can be determined by INDEX model calculations. Deduced values from publishedn- andp-spectra agree reasonably well with those of other experimental analyses but deviate significantly from microscopic model predictions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01289630
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Analysis of excitation functions from light ion induced reactions in the EXCLUSIVE INDEX model (1989)
    Springer
    The European physical journal 333 (1989), S. 45-56 
    Details
    ISSN: 1434-601X
    Keywords: 24.60.Dr ; 24.60.Gv ; 25.40.−h ; 25.45.−z ; 25.55.−e ; 25.70.Gh
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The previously introduced EXCLUSIVE INDEX model allows to predict the population of 6 residual nuclei including the primary compound nucleus through two stages of the preequilibrium phase. The present version is limited to maximum two-nucleon emission. The preequilibrium ejectiles may reduce the brought-in rotational energy by a model of maximum angular momentum decoupling. Subsequent evaporation of protons, neutrons andα-particles is treated in the frame of the Weisskopf-Ewing ands-wave approximation considering pairing effects only in compound nucleus state densities. The sensitivity of essential preequilibrium parameters on the shape of calculated excitation functions is tested. The model predictions well compare to excitation functions fromp, d,3He and4He induced reactions including the large set from the reaction93Nb(4He,xn yp) up to 170 MeV bombarding energy. The general importance of two-nucleon preequilibrium emission is accentuated in several examples. The deduced preequilibrium parameters corroborate the results from the INDEX model analysis of nucleon spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01290109
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    Paper (German National Licenses)
    Fulltext
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