Development of a “fission-proxy” method for the measurement of 14-MeV neutron fission yields

2018 ◽  
Vol 106 (8) ◽  
pp. 627-630
Author(s):  
Narek Gharibyan ◽  
Ken Moody ◽  
Scott Tumey ◽  
Tom Brown ◽  
Pat Grant ◽  
...  
Keyword(s):  
Compound Nucleus ◽  
Reaction Pathway ◽  
Fission Products ◽  
Quantitative Comparison ◽  
Fission Yield ◽  
Neutron Fission ◽  
New Approach ◽  
Independence Hypothesis ◽  
Induced Fission ◽  
Fission Yields

Abstract Relative fission-yield measurements were made for 50 fission products from 25.6±0.5 MeV α-induced fission of Th-232. Quantitative comparison of these experimentally measured yields with the evaluated fission yields from 14-MeV neutrons on U-235 demonstrates the application of the Bohr-independence hypothesis for measuring fission yields. As optimum particle-target configurations may be impossible or compromised at a given facility, this new approach, fission-proxy, allows the measurement of fission yields for a given compound nucleus from an alternate reaction pathway since formation and subsequent decay are independent processes.

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 Fission studies at IGISOL/JYFLTRAP: Simulations of the ion guide for neutron-induced fission and comparison with experimental data

2020 ◽  
Vol 239 ◽  
pp. 17019
Author(s):  
Z. Gao ◽  
A. Solders ◽  
A. Al-Adili ◽  
L. Canete ◽  
T. Eronen ◽  
...  
Keyword(s):  
Extraction Efficiency ◽  
Fission Products ◽  
Recent Measurement ◽  
Buffer Gas ◽  
Fission Yield ◽  
Fission Fragments ◽  
Ion Guide ◽  
Igisol Facility ◽  
Induced Fission ◽  
Fission Yields

For the production of exotic nuclei at the IGISOL facility, an ion guide for neutron-induced fission has been developed and tested in experiments. Fission fragments are produced inside the ion guide and collected using a helium buffer gas. Meanwhile, a GEANT4 model has been developed to simulate the transportation and stopping of the charged fission products. In a recent measurement of neutron-induced fission yields, implantation foils were located at different positions in the ion guide. The gamma spectra from these foils and the fission targets are compared to the results from the GEANT4 simulation. In order to allow fission yield measurements in the low yield regions, towards the tails and in the symmetric part of the mass distribution, the stopping and extraction efficiency of the ion guide has to be significantly improved. This objective can be achieved by increasing the size while introducing electric field guidance using a combination of static electrodes and an RF-carpet. To this end, the GEANT4 model is used to optimise the design of such an ion guide.

Cumulative yields of stable and long-lived isotopes of tin in neutron-induced fission

1983 ◽  
Vol 61 (11) ◽  
pp. 1490-1497 ◽  
Author(s):  
K. J. R. Rosman ◽  
J. R. De Laeter ◽  
J. W. Boldeman ◽  
H. G. Thode
Keyword(s):  
Stable Isotopes ◽  
Fine Structure ◽  
Fission Product ◽  
Mass Spectrometer ◽  
Smooth Curve ◽  
Mass Region ◽  
Neutron Fission ◽  
Source Mass ◽  
Induced Fission ◽  
Fission Yields

The relative cumulative fission yields of the six stable isotopes of tin (117Sn,118Sn, 119Sn, 120Sn, 122Sn, and 124Sn) and the long-lived isotope 126Sn have been measured in the thermal and epicadium neutron fission of 233U and 235U, and the epicadium neutron fission of 238U. Nanogram-sized fission product tin samples were extracted from irradiated uranium samples and analyzed in a solid source mass spectrometer. In each case a smooth curve can be drawn through the yield points of the seven isotopes of tin. There is, therefore, no evidence of "fine structure" in the 117 ≤ A ≤ 126 portion of the symmetric mass region.

scholarly journals Fission Product Yield Measurements from Neutron-Induced Fission of 235,238 U and 239Pu

2020 ◽  
Vol 232 ◽  
pp. 03006
Author(s):  
M. A. Stoyer ◽  
A. P. Tonchev ◽  
J. A. Silano ◽  
M. E. Gooden ◽  
J. B. Wilhelmy ◽  
...  
Keyword(s):  
Fission Product ◽  
Nuclear Physics ◽  
Fission Products ◽  
Product Yield ◽  
Tandem Accelerator ◽  
Precision Data ◽  
High Precision Data ◽  
Induced Fission ◽  
The Impact ◽  
Fission Yields

Fission product yields (FPY) are one of the most fundamental quantities that can be measured for a fissioning nucleus and are important for basic and applied nuclear physics. Recent measurements using mono-energetic and pulsed neutron beams generated using Triangle Universities Nuclear Laboratory’s tandem accelerator and employing a dual fission chamber setup have produced self-consistent, high-precision data critical for testing fission models for the neutron-induced fission of 235,238U and 239Pu between neutron energies of 0.5 to 15.0 MeV. These data have elucidated a low-energy dependence of FPY for several fission products using irradiations of varying lengths and neutron energies. This paper will discuss new measurements just beginning utilizing a RApid Belt-driven Irradiated Target Transfer System (RABITTS) to measure shorterlived fission products and the time dependence of fission yields, expanding the measurements from cumulative towards independent fission yields. The uniqueness of these FPY data and the impact on the development of fission theory will be discussed.

Cumulative yields of stable and long-lived isotopes of ruthenium and palladium in neutron-induced fission

1978 ◽  
Vol 56 (10) ◽  
pp. 1340-1352 ◽  
Author(s):  
Masako Shima ◽  
H. G. Thode ◽  
R. H. Tomlinson
Keyword(s):  
Thermal Neutron ◽  
Isotope Dilution ◽  
Yield Curve ◽  
Mass Region ◽  
Mass Yield ◽  
Neutron Fission ◽  
Significant Depression ◽  
Thermal Neutron Fission ◽  
Induced Fission ◽  
Fission Yields

The relative cumulative yields of nine stable and long-lived isotopes of ruthenium and palladium (masses 101 to 110) produced in the thermal neutron fission of 233U and in the thermal and epicadmium neutron fission of 235U and 239Pu have been measured using a solid source mass spectrometer and isotope dilution techniques. Absolute yields of these isotopes for the thermal neutron fission of 233U, 235U, and 239Pu are obtained using normalization procedures. These yields provide the first experimentally determined yields of the palladium masses 105, 106, 107, 108, and 110.In the thermal fission of 233U and 235U the ruthenium isotope yields obtained are in general agreement with previously determined values, although discrepancies exist of the order of 10% at masses 103, 104, and 106 for thermal fission of 235U.A plot of the ruthenium and palladium isotope mass yields together with the previously determined yields for the cadmium and tin isotopes indicate a significant depression in the mass yield curve at masses 111 and 114 for 233U and 235U thermal fission, respectively. In the 235U epicadmium fission, yields at even mass numbers are relatively higher than those at odd numbers, resulting in a zigzag yield curve in the 101 to 110 mass region.

ABSOLUTE YIELDS OF THE XENON AND KRYPTON ISOTOPES IN U238 SPONTANEOUS FISSION

1960 ◽  
Vol 38 (1) ◽  
pp. 1-9 ◽  
Author(s):  
B. G. Young ◽  
H. G. Thode
Keyword(s):  
Fission Product ◽  
Spontaneous Fission ◽  
Fission Products ◽  
Inert Gases ◽  
Geological Time ◽  
Neutron Fission ◽  
Fission Gas ◽  
Thermal Neutron Fission ◽  
Induced Fission ◽  
The Absolute

The absolute abundances of the isotopes of fission-product xenon and krypton in six uranium minerals have been determined mass spectrometrically using the isotope dilution technique. The fission products were resolved into a U238 spontaneous fission component, a U235 neutron-induced fission component, and a U238 neutron-induced fission component. Internal consistency in the analysis was achieved only when the Xe129 yield used for the U235 thermal neutron fission component was 20% lower than that reported by Purkayastha and Martin at I129. This discrepancy in the mass 129 chain yield measured at I129 and at Xe129 has not been resolved.Only one of the six minerals, Cinch Lake pitchblende, retained essentially all of its fission product inert gases throughout geological time. Inert gas losses from the remaining five minerals ranged from 20% to 75%. The absolute yields of the stable xenon and krypton fission products in U238 spontaneous fission were determined from an analysis of the inert gases from the Cinch Lake mineral. This analysis showed that 95.9% of the fission gas in this case resulted from the spontaneous fission and only 4.1% from neutron-induced fission.

THE RELATIVE ABUNDANCES OF NEODYMIUM AND SAMARIUM ISOTOPES IN THE THERMAL NEUTRON FISSION OF U235 AND U233

1955 ◽  
Vol 33 (5) ◽  
pp. 830-837 ◽  
Author(s):  
E. A. Melaika ◽  
M. J. Parker ◽  
J. A. Petruska ◽  
R. H. Tomlinson
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Neutron Capture ◽  
Natural Uranium ◽  
Fission Yield ◽  
Yield Data ◽  
Neutron Fission ◽  
Thermal Neutron Fission ◽  
The Cross ◽  
Fission Yields

The relative fission yields of neodymium and samarium isotopes have been measured with a mass spectrometer for samples of natural uranium and U233 that had been irradiated with moderated neutrons. The cross sections for neutron capture by Sm149 and Sm151 have been determined to be 66,200 ± 2500 barns and 12,000 barns respectively, relative to the cross section of a B10 monitor. The half-lives of Pm147 and Sm151 have been evaluated to be 2.52 ± 0.08 yr. and ~93 yr., respectively, from samarium fission yield data for samples differing in age by seven years.

scholarly journals Toward short-lived and energy-dependent fission product yields from neutron-induced fission

2020 ◽  
Vol 239 ◽  
pp. 03001
Author(s):  
Anton P Tonchev ◽  
Jack A Silano ◽  
Chris Hagmann ◽  
Roger Henderson ◽  
Mark A Stoyer ◽  
...  
Keyword(s):  
Fission Product ◽  
Fission Products ◽  
Incident Neutron ◽  
Tandem Accelerator ◽  
Precision Data ◽  
Product Yields ◽  
Fission Product Yields ◽  
Induced Fission ◽  
Energy Dependent ◽  
Fission Yields

Fission product yields (FPYs) are an important source of information that are used for basic and applied physics. They are essential observables to address questions relevant to nucleosynthesis in the cosmos that created the elements from iron to uranium, for example, in energy generating processes from fission recycling in binary neutron star mergers; resolving the reactor neutrino anomaly; decay heat release in nuclear reactors; and many national security applications. While new applications will require accurate energy-dependent FPY data over a broad set of incident neutron energies, the current evaluated FPY data files contain only three energy points: thermal, fast, and 14-MeV incident energies. Recent measurements using mono-energetic and pulsed neutron beams at the Triangle Universities Nuclear Laboratory (TUNL) tandem accelerator and employing a dual fission ionization chambers setup have produced self-consistent, high-precision data critical for testing fission models for the neutron-induced fission of the major actinide nuclei. This paper will present new campaign just beginning utilizing a RApid Belt-driven Irradiated Target Transfer System (RABITTS) to measure shorter-lived fission products and the time dependence of fission yields, expanding the measurements from cumulative towards independent fission yields.

scholarly journals Studies of fission fragment yields via high-resolution γ-ray spectroscopy

2018 ◽  
Vol 169 ◽  
pp. 00030
Author(s):  
J.N. Wilson ◽  
M. Lebois ◽  
L. Qi ◽  
P Amador-Celdran ◽  
D. Bleuel ◽  
...  
Keyword(s):  
High Resolution ◽  
Fast Neutron ◽  
Fission Products ◽  
Spectroscopic Technique ◽  
Experimental Investigations ◽  
Incident Neutron ◽  
Yield Data ◽  
Spectroscopic Information ◽  
Induced Fission ◽  
Fission Yields

Precise spectroscopic information on the fast neutron induced fission of the 238U(n,f) reaction was recently gained using a new technique which involved coupling of the Miniball high resolution y-ray spectrometer and the LICORNE directional neutron source. The experiment allowed measurement of the isotopic fission yields for around 40 even-even nuclei at an incident neutron energy of around 2 MeV where yield data are very sparse. In addition spectroscopic information on very neutron-rich fission products was obtained. Results were compared to models, both the JEFF-3.1.1 data base and the GEF code, and large discrepancies for the S1 fission mode in the Sn/Mo isotope pair were discovered. This suggests that current models are overestimating the role played by spherical shell effects in fast neutron induced fission. In late 2017 and 2018 the nu-ball hybrid spectrometer will be constructed at the IPN Orsay to perform further experimental investigations with directional neutrons coupled to a powerful hybrid Ge/LaBr3 detector array. This will open up new possibilities for measurements of fission yields for fast-neutron-induced fission using the spectroscopic technique and will be complimentary to other methods being developed.

ON THE PRODUCTION OF Be7, Mg28, AND Ni66 IN THE SLOW NEUTRON FISSION OF U235

1961 ◽  
Vol 39 (2) ◽  
pp. 315-325 ◽  
Author(s):  
J. C. Roy
Keyword(s):  
Current Knowledge ◽  
Slow Neutron ◽  
Fission Yield ◽  
Neutron Fission ◽  
Upper Limits ◽  
Fission Yields

The yields of 53-day Be7, 21.3-hour Mg28, and 56.6-hour Ni66 from the slow neutron fission of U235 have been investigated. Upper limits of 3 × 10−7% and 4.2 × 10−9% have been set for the fission yields of Be7 and Mg28 respectively. A fission yield of 2.0 ± 1.0 × 10−8% has been found for the formation of Ni66. These results are compared with the current knowledge of the frequency of triple fission of U235.

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