Title: Comparing different energy partitions at scission used in prompt emission model codes GEF and Point-by-Point
Authors: TUDORA ANABELLAHAMBSCH Franz-JosefVISAN I.GIUBEGA G.
Citation: NUCLEAR PHYSICS A vol. 940 p. 242-263
Publisher: ELSEVIER SCIENCE BV
Publication Year: 2015
JRC N°: JRC96372
ISSN: 0375-9474
URI: http://www.sciencedirect.com/science/article/pii/S0375947415001086
http://publications.jrc.ec.europa.eu/repository/handle/JRC96372
DOI: 10.1016/j.nuclphysa.2015.04.012
Type: Articles in periodicals and books
Abstract: Different methods to partition the total excitation energy (TXE) of fully accelerated fragments, presently used in prompt emission calculations include different assumptions about what is happening at scission. In fact the energy partition takes place at scission or even before scission, depending on the physical assump-tions supporting the models used in different methods of TXE partition. The paper discusses two TXE partition methods in which the amount of energy to be shared (at scis-sion and before scission, respectively) is very different. These methods (based on different principles and physical considerations) are: A.The method used in the Point-by-Point (PbP) treatment of prompt emission in which the available excitation energy at scission is shared between complementary nascent fragments. The amount of energy to be shared is sufficiently high to consider the nascent fragments in the Fermi-gas regime of the level density. B.The method used in the GEF code, in which the intrinsic energy before scis-sion is shared between pre-nascent fragments according to the “energy sorting mechanism”. This sorting mechanism is based on the assumption of level densities in the constant temperature regime, only. This is supported by the low amount of the shared intrinsic energy in the case of thermal and low energy neutron induced fission. Taking into account that the principles and physical considerations of any TXE partition method are independent on the way to treat the prompt emission (i.e. deterministically as in the PbP model or probabilis-tically by Monte-Carlo as in the code GEF) the methods A and B are applied to the same fission fragment range (built as in the PbP treatment). Extreme hypotheses are made for the fragment level densities on which the partitions are based (only in the Fermi-gas regime or only in the constant temperature regime). The results are compared with the energy partition obtained with fragment level densities described by the composite Gilbert–Cameron formula. Different assumptions for the deformation energies of fragments (absolute deformation at scission, or extra-deformation at scission with respect to the full acceleration) impacting the sawtooth-like shape of the excitation energy E∗(A)at full acceleration are discussed, too. Limitations and advantages of these methods are also mentioned. Both TXE partition methods applied in the PbP model lead to prompt emission results (e.g. ν(A)and Eγ(A)) describing well the experimental data.
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