Prompt fission neutron data calculation using experimental fission fragment charge distributions in the frame of the Point by Point treatment

The experimental fission fragment (FF) mass distributions are important ingredients for the Point by Point (PbP) model calculation of multiplicity, spectra and other quantities related to the prompt neutron emission. For many fissioning systems experimental FF mass distributions are missing and in these cases an original procedure, exploiting available experimental FF charge distributions in the frame of PbP treatment, is proposed.     

“Point by Point” model calculation of prompt neutron emission data for Cm(SF) and Cm(SF)

This work is devoted to the modeling of the prompt neutron emission in the spontaneous fission of ^248,244Cm. The Point by Point model calculations of relevant quantities (like: the multi-parametric matrix ν(A, TKE), the fission fragment multiplicity as a function of fragment mass (usually named sawtooth) ν(A), fission fragment pair multiplicity as a function of total excitation energy ν_pair(TXE), total average prompt neutron multiplicity 〈ν_p〉 and spectra N(E), total average multiplicity as a function of the total kinetic energy 〈ν_p〉 (TKE) describe very well all existing experimental data.     

Point by Point model calculation of the prompt neutron multiplicity distribution P(ν) for spontaneous and neutron induced fission of actinides

The prompt neutron multiplicity distribution P(ν) is a very sensitive quantity which depends on the model calculation of the multi-parametric matrix ν(A,TKE) and on the fission fragment distributions.     

Characterization and deposition behavior of silk hydrogels soaked in simulated body fluid

This paper reports the mineralization ability of semi-interpenetrating networks composed of regenerated silk fibroin and polyacrylamide hydrogels soaked in simulated body fluid (SBF1x). Hydrogels were prepared by polymerization of acrylamide and N,N′-methylenebisacrylamide in silk fibroin solution with a redox pair as initiator. The incorporation of the fibroin within the polyacrylamide matrix was proved by FTIR–ATR spectroscopy. Swelling measurements in saline solution were performed to evaluate the behavior of these hydrogels having various compositions. Mineralization assays in SBF1x solution revealed the presence of apatite-like crystals onto the surface of the silk fibroin/polyacrylamide hydrogels. Cytotoxicity test by extract method revealed that these hydrogels with various contents in silk fibroin have not developed cytotoxic effects on human fibroblast cultures which increases the possibility of their use in biomedical applications. Mechanical compressive tests revealed good strengths for silk fibroin/polyacrylamide hydrogels. In this way, organic–inorganic hybrids analogous to bone structure can be produced under biomimetic conditions and could be further used in biomedical applications.     

Multi-parametric prompt neutron and fission fragment experimental data described by the “Point by Point” model

The experimental multi-parametric data concerning the prompt neutron multiplicity as a function of fission fragment mass and total kinetic energy as well as other experimental data like the total excitation energy of the fission fragment pair versus the fragment mass, the prompt neutron average center-of-mass energy as a function of the fragment mass, the total average multiplicity as a function of the fission fragment total kinetic energy and the average prompt γ-ray energy versus the fragment mass, when they exist, allow much more detailed verification of the models and parameter determination used to evaluate the prompt neutron multiplicity and spectrum data.     

Systematic behaviour of the average parameters required for the Los Alamos model of prompt neutron emission

A large number of fissioning systems have been studied in the frame of the Los Alamos model which showed interesting regular behaviours of the average model parameters (the energy release in fission 〈E_r〉, the total kinetic energy of the fission fragments 〈TKE〉, the average neutron separation energy 〈S_n〉 from the fission fragments, the prompt gamma-ray energy 〈E_γ〉 and the level density parameter 〈a〉 parameterized as 〈C〉 = A/〈a〉, where A is the mass number of the fissioning nucleus)) as well as of other quantities in connection with the prompt fission neutron emission (such as the total average prompt neutron multiplicity at thermal incident energy, the total average fission fragment excitation energy leading to prompt neutron emission, the total average prompt fission energy deposition, the average excitation energy given to the fragments, and the average center-of-mass energy of prompt neutrons and so on) and to elaborate systematics of model parameters.     

Neutron cross-sections of Pu in the energy range 5–20 MeV

The evaluation of neutron cross sections and angular distributions of ²⁴²Pu in the energy range 5–20 MeV was performed using the direct interaction treatment by coupled channel method and the compound nucleus mechanism (statistical model) taking account of pre-equilibrium effects. The calculated cross-sections are in very good agreement with the existing experimental data (total and fission cross-sections). More accurate theoretical data have been obtained by the extension of procedures and parameterizations (previously used only for the main compound nucleus) in the incident neutron energy range where more compound nuclei are involved.     

Approach for the fission fragment total kinetic energy TKE(A) calculation: Application to prompt neutron emission models

A simple approach for the calculation of the fission fragment total kinetic energy, TKE(A), based on the electrostatic repulsion between the fragments connected by a neck in the pre-scission configuration is described. The calculated TKE(A) is obtained in good agreement with the experimental data for many fissioning systems, such as ^233,235U(n_th, f), ²³⁹Pu(n_th, f), ²³⁷Np(n, f), ²⁴²Pu(SF), with minor adjustment of only one parameter. Due to the fact that the present approach can provide with enough trust TKE(A) distributions for fissioning systems for which experimental TKE(A) data do not exist, the possibilities to use the refined Point by Point model of prompt neutron emission can be considerably extended.