scholarly journals Implementing and testing theoretical fission fragment yields in a Hauser-Feshbach statistical decay framework

2018 ◽  
Vol 169 ◽  
pp. 00006 ◽  
Author(s):  
Patrick Jaffke ◽  
Peter Möller ◽  
Ionel Stetcu ◽  
Patrick Talou ◽  
Christelle Schmitt
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Fission Fragment ◽  
Energy Surface ◽  
Prompt Neutron ◽  
Fission Fragments ◽  
Statistical Decay ◽  
Γ Ray ◽  
The Impact

We implement fission fragment yields, calculated using Brownian shape-motion on a macroscopic-microscopic potential energy surface in six dimensions, into the Hauser-Feshbach statistical decay code CGMF. This combination allows us to test the impact of utilizing theoretically-calculated fission fragment yields on the subsequent prompt neutron and γ-ray emission. We draw connections between the fragment yields and the total kinetic energy TKE of the fission fragments and demonstrate that the use of calculated yields can introduce a difference in the 〈TKE〉 and, thus, the prompt neutron multiplicity v, as compared with experimental fragment yields. We deduce the uncertainty on the 〈TKE〉 and v from this procedure and identify possible applications.

Photochemistry of van der Waals Complexes and Small Clusters

1996 ◽  
Author(s):  
C. Jouvet ◽  
D. Solgadi
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Internal Energy ◽  
Energy Surface ◽  
Van Der Waals ◽  
Van Der Waals Complexes ◽  
Small Subset ◽  
Energy Effect ◽  
Precise Control

In a chemical reaction, the shape of the potential energy surface (PES) dictates the reaction rate and energy disposal in the products. Not only does the dynamics depend crucially upon the features of the surface, but, ultimately one seeks to influence the course of the reaction by preparing selectively certain regions of the surface. For harpooning reactions, the propensity rules for energy disposal in the products (influence of the entrance kinetic energy, effect of the early or late barrier) have been established by Polanyi (1972) and have been used later as guidelines. Here, the surface may easily be modeled in simple terms using long-range electrostatic interaction in the entrance valley. There was, then, need of an experimental method which allows the possibility of observing directly the characteristic regions of this potential energy surface, but also to investigate precisely the surface in other types of reaction. The study of the reactivity of van der Waals complexes is intended to fulfil this purpose. In classical experiments, the surface is obtained by inversion of the experimental data which are differential cross sections and internal energy distribution of the products. This procedure is difficult and not unambiguous. The first step is to determine the correlation between the entrance channel's parameters (kinetic energy, internal energy, angular momentum) and the final states of the products (kinetic energy, internal energy, angular distribution). This requires a precise control of the entrance channel. Therefore, the goal of many experiments is to reduce the initial states to a small subset, and to measure the energy disposal in the products with the greatest accuracy. This was first achieved by controlling the kinetic energy of the reactants in crossed beam experiments. Later, a certain control of the collision geometry was obtained by orienting the molecules or the atomic orbitals in crossed beam experiments or by using prealigned systems in a van der Waals complex: this subject is discussed in Buelow et al. (1986).

scholarly journals Calculation of the fission observables in the resolved resonance energy region of the 235U(n,f) reaction

2020 ◽  
Vol 239 ◽  
pp. 05002
Author(s):  
Olivier Serot ◽  
Olivier Litaize ◽  
Abdelhazize Chebboubi
Keyword(s):  
Kinetic Energy ◽  
Fission Fragment ◽  
Energy Region ◽  
Resonance Energy ◽  
Neutron Multiplicity ◽  
Prompt Neutron ◽  
Incident Neutron ◽  
Monte Carlo Code ◽  
Fission Fragments ◽  
Free Parameters

Measurement of the fission fragments in coincidence with the emitted prompt neutrons was undertaken recently, at JRC-Geel institute, for the 235U(n,f) reaction in the resolved resonance energy region, up to 160 eV incident neutron energy. From this experimental work, fluctuations of several fission observables (mass yields, average total kinetic energy T̅K̅E̅, average prompt neutron multiplicity v̅P) were clearly observed. In the present work, these experimental pre-neutron fission fragment mass and kinetic energy distributions were used as input data for the FIFRELIN Monte Carlo code. By adopting the Hauser-Feshbach statistical model, the code simulates the de-excitation of the fission fragments. Four free parameters are available in the code: two of them (called RTmin and RTmax) govern at the scission point the sharing of the total available excitation energy between the two nascent fission fragments, while the two others (called σL and σH) assign the initial fission fragment spins. In this way, fission observables (prompt particles energy spectra and multiplicities, delayed neutrons multiplicity,. . . ) and correlations between them can be predicted and investigated. Here, these four free parameters were tuned in order to reproduce the average prompt neutron multiplicity at the resonance En=19.23 eV, resonance for which the experimental statistical uncertainty on v̅P is the lowest one. Then, the calculations were perfomed for all resonances by keeping the same set of free parameters. We show that the calculated fluctuations of v̅P in the resonances can rather be well reproduced by considering only the fluctuations of the pre-neutron mass yields and kinetic energy. In addition, from our calculation procedure, other fission observables fluctuations can also be predicted.

THEORETICAL STUDIES OF $\tilde{A}{}^1 A^{\prime\prime}\to\tilde{X}{}^1 A^\prime$ RESONANCE EMISSION SPECTRA OF HCN/DCN USING SINGLE LANCZOS PROPAGATION METHOD

2003 ◽  
Vol 02 (04) ◽  
pp. 639-648 ◽  
Author(s):  
DINGGUO XU ◽  
HUA GUO ◽  
DAIQIAN XIE
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Energy Surface ◽  
Emission Spectra ◽  
Theoretical Work ◽  
Stimulated Emission ◽  
Transition Dipole ◽  
Resonance Emission ◽  
State Potential ◽  
The Impact

Using an efficient single Lanczos propagation method, we report the [Formula: see text] resonance emission spectra of HCN and DCN from a number of low-lying vibrational levels of the Ã-state manifold. Our calculations represent the first such undertaking in which a high-quality ab initio based potential energy surface of the excited (Ã1 A″) state and a [Formula: see text] transition dipole surface were used. The results show a significant improvement over previous theoretical work in reproducing experimental stimulated emission pumping spectra of HCN. The improved theory-experiment agreement is attributed to the accurate Ã-state potential energy surface, while the impact of the transition dipole function was found to be relatively minor.

An accurate, global, ab initio potential energy surface for the H + 3 molecule

2000 ◽  
Vol 98 (5) ◽  
pp. 261-273 ◽  
Author(s):  
Oleg L. Polyansky, Rita Prosmiti, Wim Kl
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Energy Surface

HIGH ACCURACY POTENTIAL ENERGY SURFACE, DIPOLE MOMENT SURFACE, ROVIBRATIONAL ENERGIES AND LINE LIST CALCULATIONS FOR 14NH3

2017 ◽  
Author(s):  
Phillip Coles ◽  
Jonathan Tennyson ◽  
Nikolay Zobov ◽  
Roman Ovsyannikov ◽  
Aleksandra Kyuberis ◽  
...  
Keyword(s):  
Dipole Moment ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Energy Surface ◽  
High Accuracy ◽  
Line List ◽  
Surface Dipole ◽  
Rovibrational Energies
Sign in / Sign up

Export Citation Format

Share Document