scholarly journals Neutron Multiplicity Correlations with Fission Fragment Mass and Energy from 239Pu(n,f)

2020 ◽  
Vol 239 ◽  
pp. 05009
Author(s):  
Alf Göök ◽  
Franz-Josef Hambsch ◽  
Stephan Oberstedt

There exists experimental evidence for strong fluctuations of the average neutron multiplicity from resonance to resonance in 239Pu(n,f). These fluctuations have been shown to impact nuclear reactor benchmarks by reducing the criticality. The fluctuating neutron multiplicity can be explained as a consequence of the competition between direct fission and the (n,γf) process. However, there is also evidence for fluctuations of the fission fragment mass yields from resonance to resonance. The mass yield fluctuations may also contribute to fluctuations of the neutron multiplicity averaged over all fission fragment masses. In order to model the contribution to the neutron multiplicity fluctuations by the fission fragment mass yield fluctuations new data on the correlations between fission fragment properties and neutron multiplicities are in need. We present experiments carried out to determine prompt neutron multiplicity correlations with fission fragment masses and total kinetic energies in the reaction 239Pu(n,f). The experiment has been performed at the GELINA facility at JRC-Geel. A twin position-sensitive Frisch-grid ionization chamber is used for fission fragment identification via the double kinetic energy technique. An array of scintillation detectors is employed for neutron counting. Correlations between average neutron multiplicities and fission fragment properties have been measured with improved resolution in both mass and TKE, compared to data from the literature.

2019 ◽  
Vol 211 ◽  
pp. 04002 ◽  
Author(s):  
D. Doré ◽  
E. Berthoumieux ◽  
Q. Deshayes ◽  
L. Thulliez ◽  
P. Legou ◽  
...  

The renewed interest for the study of nuclear fission is mainly motivated by the development of GEN-IV reactor concepts, mostly foreseen to operate in the fast neutron energy domain. To support this development, new high-quality nuclear data are needed. In this context, a new experimental setup, the FALSTAFF spectrometer, dedicated to the study of nuclear fission is under development. Employing the double-velocity (2V) and energy-velocity (EV) methods, the fission fragment mass before and after neutron evaporation will be deduced and the correlation between prompt neutron multiplicity and fragment mass will be determined. The first arm of the spectrometer is achieved. It is composed of two SED-MWPC detectors (a combination of a foil to produce secondary electrons and a Multi-Wire Proportional Chamber to detect them) and an axial ionization chamber. The SED-MWPC give access to the velocity (V) via time-of-flight and position measurements. The ionization chamber measures the fragment kinetic energy (E) and the energy loss profile. Preliminary results for spontaneous fission of 252Cf and from the thermal-neutron induced fission experiment on 235U, performed at the Orphée reactor (CEA-Saclay, France), are presented.


2018 ◽  
Vol 27 (01) ◽  
pp. 1850002
Author(s):  
V. Yu. Denisov ◽  
O. A. Belyanovska ◽  
V. P. Khomenkov ◽  
I. Yu. Sedykh ◽  
K. M. Sukhyy

Simple expression for the temperature dependence of the width of fission-fragment mass yields is obtained for high excitation energies. The width depends on the number of nucleons in nuclei, the volume and surface terms of the energy level density parameter, the temperature and the stiffness parameter of the potential related to mass-asymmetric degree of freedom. The contribution of the surface term of the energy level density parameter into the width is important at temperatures [Formula: see text][Formula: see text]MeV.


2009 ◽  
Author(s):  
N. Carjan ◽  
M. Rizea ◽  
Audrey Chatillon ◽  
Herbert Faust ◽  
Gabriele Fioni ◽  
...  

1994 ◽  
Vol 578 (1-2) ◽  
pp. 77-92 ◽  
Author(s):  
J. van Aarle ◽  
W. Westmeier ◽  
R.A. Esterlund ◽  
P. Patzelt

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