ELISe: A NEW FACILITY FOR UNPRECEDENTED EXPERIMENTAL NUCLEAR FISSION STUDIES

2009 ◽  
Vol 18 (04) ◽  
pp. 767-772 ◽  
Author(s):  
J. TAIEB ◽  
G. BELIER ◽  
A. CHATILLON ◽  
T. GRANIER ◽  
A. KELIC ◽  
...  
Keyword(s):  
Inverse Kinematics ◽  
Total Mass ◽  
Nuclear Fission ◽  
Experimental Program ◽  
Fission Process ◽  
Fission Fragments ◽  
Charge Resolution ◽  
New Facility

A novel experimental program aiming to study the properties of fragments and neutrons emitted in the fission process has been initiated. The experiment will be held at the ELISe electron-ion collider to be constructed at GSI, Darmstadt in the framework of the FAIR extension of the facility. The experiment will take advantage of the inverse kinematics allowing, in particular, a total mass and charge resolution for all fission fragments.

scholarly journals Fission fragments observables measured at the LOHENGRIN spectrometer

2020 ◽  
Vol 239 ◽  
pp. 05017
Author(s):  
S. Julien-Laferrière ◽  
L. Thombansen ◽  
G. Kessedjian ◽  
A. Chebboubi ◽  
O. Serot ◽  
...  
Keyword(s):  
Neutron Emission ◽  
Evaluation Process ◽  
Nuclear Data ◽  
Nuclear Fission ◽  
Experimental Program ◽  
Spent Fuel ◽  
Ionic Charge ◽  
Fission Fragments ◽  
Common Effort ◽  
Fission Yields

Nuclear fission yields are key data for reactor studies, such as spent fuel inventory or decay heat, and for understanding fission process. Despite a significant effort allocated to measure fission yields during the last decades, the recent evaluated libraries still need improvements in particular in the reduction of the uncertainties. Moreover, some discrepancies between these libraries must be explained. Additional measurements provide complementary information and estimations of experimental correlations, and new kinds of measurements enable to test the models used during the nuclear data evaluation process. A common effort by the CEA, the LPSC and the ILL aims at tackling these issues by providing precise measurements of isotopic and isobaric fission yields with the related variance-covariance matrices. Additionally, the experimental program involves a large range of observables requested by the evaluations, such as kinetic energy dependency of isotopic yields and odd-even effect in order to test the sharing of total excitation energy and the spin generation mechanism. Another example is the complete range of isotopic distribution per mass that allows the determination of the charge polarization, which has to be consistent for complementary masses (pre-neutron emission). For instance, this information is the key observable for the evaluation of isotopic yields. Finally, ionic charge distributions are indirect measurements of nanosecond isomeric ratios as a probe of the nuclear de-excitation path in the (E*, J, π) representation. Measurements for thermal neutron induced fission of 241 Pu have been carried out at the ILL in Grenoble, using the LOHENGRIN mass spectrometer. Methods, results and comparison to models calculations will be presented corresponding to a status on fission fragments observables reachable with this facility.

scholarly journals From fission yield measurements to evaluation: status on statistical methodology for the covariance question

2018 ◽  
Vol 4 ◽  
pp. 26 ◽  
Author(s):  
Brieuc Voirin ◽  
Grégoire Kessedjian ◽  
Abdelaziz Chebboubi ◽  
Sylvain Julien-Laferrière ◽  
Olivier Serot
Keyword(s):  
Statistical Tests ◽  
Fission Products ◽  
Experimental Program ◽  
Mass Yield ◽  
Statistical Methodology ◽  
Fission Yield ◽  
Fission Process ◽  
Induced Fission ◽  
Entropy Criterion ◽  
Fission Yields

Studies on fission yields have a major impact on the characterization and the understanding of the fission process and are mandatory for reactor applications. Fission yield evaluation represents the synthesis of experimental and theoretical knowledge to perform the best estimation of mass, isotopic and isomeric yields. Today, the output of fission yield evaluation is available as a function of isotopic yields. Without the explicitness of evaluation covariance data, mass yield uncertainties are greater than those of isotopic yields. This is in contradiction with experimental knowledge where the abundance of mass yield measurements is dominant. These last years, different covariance matrices have been suggested but the experimental part of those are neglected. The collaboration between the LPSC Grenoble and the CEA Cadarache starts a new program in the field of the evaluation of fission products in addition to the current experimental program at Institut Laue-Langevin. The goal is to define a new methodology of evaluation based on statistical tests to define the different experimental sets in agreement, giving different solutions for different analysis choices. This study deals with the thermal neutron induced fission of 235U. The mix of data is non-unique and this topic will be discussed using the Shannon entropy criterion in the framework of the statistical methodology proposed.

scholarly journals Description of the Fission Process: Nuclear Models for Fission Dynamics

2020 ◽  
Vol 242 ◽  
pp. 03005
Author(s):  
M. Verriere ◽  
M.R. Mumpower ◽  
T. Kawano ◽  
N. Schunck
Keyword(s):  
National Security ◽  
Heavy Nucleus ◽  
First Principles ◽  
Energy Generation ◽  
Nuclear Fission ◽  
Theoretical Understanding ◽  
Fission Process ◽  
New Approaches ◽  
Nuclear Models ◽  
The Universe

Nuclear fission is the splitting of a heavy nucleus into two or more fragments, a process that releases a substantial amount of energy. It is ubiquitous in modern applications, critical for national security, energy generation and reactor safeguards. Fission also plays an important role in understanding the astrophysical formation of elements in the universe. Eighty years after the discovery of the fission process, its theoretical understanding from first principles remains a great challenge. In this paper, we present promising new approaches to make more accurate predictions of fission observables.

scholarly journals Impact of nuclear inertia momenta on fission observables

2018 ◽  
Vol 193 ◽  
pp. 01004
Author(s):  
P. Tamagno ◽  
O. Litaize
Keyword(s):  
Rigid Body ◽  
Excitation Energy ◽  
Nuclear Fission ◽  
Particle Model ◽  
Rotational Inertia ◽  
Neutron Fission ◽  
Fission Fragments ◽  
Rigid Body Model ◽  
Two Parameters ◽  
The Impact

Fission is probably the nuclear process the less accurately described with current models because it involves dynamics of nuclear matter with strongly coupled manybody interactions. It is thus diffcult to find models that are strongly rooted in good physics, accurate enough to reproduce target observables and that can describe many of the nuclear fission observables in a consistent way. One of the most comprehensive current modeling of the fission process relies on the fission sampling and Monte-Carlo de-excitation of the fission fragments. This model is implemented for instance in the FIFRELIN code. In this model fission fragments and their state are first sampled from pre-neutron fission yields, angular momentum distribution and excitation energy repartition law then the decay of both initial fragments is simulated. This modeling provides many observables: prompt neutron and gamma fission spectra, multiplicities and also fine decompositions: number of neutrons emitted as a function of the fragment mass, spectra per fragments, etc. This model relies on nuclear structure databases and on several basic nuclear models describing for instance gamma strength functions or level densities. Additionally some free parameters are still to be determined, namely two parameters describing the excitation energy repartition law, the spin cutoff of the heavy and light fragments and a rescaling parameter for the rotational inertia momentum of the fragments with respect of the rigid-body model. In the present work we investigate the impact of this latter parameter. For this we mainly substitute the corrected rigid-body value by a quantity obtained from a microscopic description of the fission fragment. The independent-particle model recently implemented in the CONRAD code is used to provide nucleonic wave functions that are required to compute inertia momenta with an Inglis-Belyaev cranking model. The impact of this substitution is analyzed on different fission observables provided by the FIFRELIN code.

scholarly journals Fission fragment yields and total kinetic energy release in neutron-induced fission of235,238U,and239Pu

2018 ◽  
Vol 169 ◽  
pp. 00024 ◽  
Author(s):  
F. Tovesson ◽  
D. Duke ◽  
V. Geppert-Kleinrath ◽  
B. Manning ◽  
D. Mayorov ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Kinetic Energy Release ◽  
Nuclear Fission ◽  
Total Kinetic Energy ◽  
Experimental Techniques ◽  
Science Center ◽  
Fission Process ◽  
Induced Fission ◽  
Time Projection ◽  
Energy Dependent

Different aspects of the nuclear fission process have been studied at Los Alamos Neutron Science Center (LANSCE) using various instruments and experimental techniques. Properties of the fragments emitted in fission have been investigated using Frisch-grid ionization chambers, a Time Projection Chamber (TPC), and the SPIDER instrument which employs the 2v-2E method. These instruments and experimental techniques have been used to determine fission product mass yields, the energy dependent total kinetic energy (TKE) release, and anisotropy in neutron-induced fission of U-235, U-238 and Pu-239.

scholarly journals The 4-dimensional Langevin approach to low energy nuclear fission

2018 ◽  
Vol 169 ◽  
pp. 00005
Author(s):  
F.A. Ivanyuk ◽  
C. Ishizuka ◽  
M.D. Usang ◽  
S. Chiba
Keyword(s):  
Excitation Energy ◽  
Mass Number ◽  
Nuclear Fission ◽  
Deformation Energy ◽  
Low Energy ◽  
Tooth Structure ◽  
Fission Fragments ◽  
Langevin Approach ◽  
Intrinsic Excitation ◽  
Mother Nucleus

We applied the four-dimensional Langevin approach to the description of fission of 235U by neutrons and calculated the dependence of the excitation energy of fission fragments on their mass number. For this we have fitted the compact just-before-scission configuration obtained by the Langevin calculations by the two separated fragments and calculated the intrinsic excitation and the deformation energy of each fragment accurately taking into account the shell and pairing effects and their dependence on the temperature and mass of the fragments. For the sharing of energy between the fission fragments we have used the simplest and most reliable assumption - the temperature of each fragment immediately after the neck rupture is the same as the temperature of mother nucleus just before scission. The calculated excitation energy of fission fragments clearly demonstrates the saw-tooth structure in the dependence on fragment mass number.

scholarly journals Measurement of fission yields and isomeric yield ratios at IGISOL

2018 ◽  
Vol 169 ◽  
pp. 00017
Author(s):  
Stephan Pomp ◽  
Andrea Mattera ◽  
Vasileios Rakopoulos ◽  
Ali Al-Adili ◽  
Mattias Lantz ◽  
...  
Keyword(s):  
Penning Trap ◽  
Mass Range ◽  
Experimental Program ◽  
Fission Yield ◽  
Yield Data ◽  
Fission Process ◽  
Isomeric Yield ◽  
First Results ◽  
Igisol Facility ◽  
Fission Yields

Data on fission yields and isomeric yield ratios (IYR) are tools to study the fission process, in particular the generation of angular momentum. We use the IGISOL facility with the Penning trap JYFLTRAP in Jyväskylä, Finland, for such measurements on 232Th and natU targets. Previously published fission yield data from IGISOL concern the 232Th(p,f) and 238U(p,f) reactions at 25 and 50 MeV. Recently, a neutron source, using the Be(p,n) reaction, has been developed, installed and tested. We summarize the results for (p,f) focusing on the first measurement of IYR by direct ion counting. We also present first results for IYR and relative yields for Sn and Sb isotopes in the 128-133 mass range from natU(n,f) based on γ-spectrometry. We find a staggering behaviour in the cumulative yields for Sn and a shift in the independent fission yields for Sb as compared to current evaluations. Plans for the future experimental program on fission yields and IYR measurements are discussed.

BINARY AND TERNARY FISSION WITHIN THE STATISTICAL MODEL

2008 ◽  
Vol 17 (10) ◽  
pp. 2014-2019 ◽  
Author(s):  
GURGEN G. ADAMIAN ◽  
ALEXANDER V. ANDREEV ◽  
NIKOLAI V. ANTONENKO ◽  
WERNER SCHEID
Keyword(s):  
Statistical Model ◽  
Nuclear Fission ◽  
Binary Fission ◽  
Ternary Fission ◽  
Scission Point ◽  
Fission Fragments ◽  
Charge Distributions

The binary and ternary nuclear fission are treated within the statistical model. At the scission point we calculate the potentials as functions of the deformations of the fragments in the dinuclear model. The potentials give the mass and charge distributions of the fission fragments. The ternary fission is assumed to occur during the binary fission.

scholarly journals Dynamical Modeling of the Nuclear Fission Process at Low Excitation Energies

2014 ◽  
Vol 02 (05) ◽  
pp. 27-31
Author(s):  
I. I. Gontchar ◽  
M. V. Chushnyakova ◽  
E. P. Oskin ◽  
E. G. Demina
Keyword(s):  
Nuclear Fission ◽  
Excitation Energies ◽  
Dynamical Modeling ◽  
Fission Process
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