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.

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.

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.

THE FISSION YIELDS OF THE STABLE AND LONG-LIVED ISOTOPES OF XENON, CESIUM, AND KRYPTON IN NEUTRON FISSION OF U233

1954 ◽  
Vol 32 (8) ◽  
pp. 522-529 ◽  
Author(s):  
W. Fleming ◽  
R. H. Tomlinson ◽  
H. G. Thode
Keyword(s):  
Fine Structure ◽  
Mass Spectrometer ◽  
Yield Curve ◽  
Closed Shell ◽  
Mass Range ◽  
The Other ◽  
Mass Yield ◽  
Fission Yield ◽  
Neutron Fission ◽  
Fission Yields

The fission yields of Xe131, Xe132, Xe134, Xe136, Cs133, Cs135, Cs137, Kr83, Kr84, 10.27 year Kr85, and Kr86 in the neutron fission of U233 have been determined by mass spectrometer methods. The very pronounced fine structure in the mass yield curve in the mass range 131 to 137 found in U235 fission does not occur in the fission of U233. This disappearance of fine structure would not have been predicted by any of the mechanisms which have been suggested to explain the fine structure in U235 fission. The fission yield of the 10.27 year isomer of Kr85 relative to the other krypton isotopes is considerably higher in U233 fission than in U235 fission, indicating some fine structure in this mass range which may be related to the closed shell of 50 neutrons.

THE FISSION YIELDS OF ISOTOPES OF XENON AND KRYPTON IN THE NEUTRON FISSION OF U236 AND U238

1955 ◽  
Vol 33 (9) ◽  
pp. 541-554 ◽  
Author(s):  
R. K. Wanless ◽  
H. G. Thode
Keyword(s):  
Fine Structure ◽  
Fast Reactor ◽  
Yield Curve ◽  
Percentage Change ◽  
Fission Yield ◽  
Los Alamos ◽  
Neutron Fission ◽  
Isotopic Abundances ◽  
Fission Yields

Several uranium samples have been irradiated under various conditions in the Chalk River N.R.X. reactor and in the Los Alamos fast reactor. The fission gases, xenon and krypton, have been extracted from the irradiated material and the relative isotopic abundances determined mass spectrometrically. Fine structure in the mass – fission yield curve has been found in both the xenon and krypton mass ranges for U235 + n and U238 + n fission. It is observed that this fine structure shifts to lower masses, as predicted, for neutron fission of U238. The proportions of U235 and U238 fission that have occurred in the irradiated samples have been estimated from the percentage change in fine structure.

FISSION YIELDS OF MASSES 131, 132, 134, AND 136 FORMED IN NEUTRON FISSION OF URANIUM

1947 ◽  
Vol 25b (4) ◽  
pp. 371-375 ◽  
Author(s):  
L. Yaffe ◽  
C. E. Mackintosh
Keyword(s):  
Relative Abundance ◽  
Fission Yield ◽  
Neutron Fission ◽  
Fission Yields

The ratio of I131 (8.0 days) to Ba140 has been determined in neutron fission of uranium and the fission yield of the former calculated to be 2.23 × 10−2 from the previously reported value for Ba140. This in turn permits the estimation of fission yields for the 132, 134, and 136 fission chains, the relative abundance of which, together with that of 131, has been obtained by Thode. The ratio of 54 min. I to Ba139 has been determined. Using the previously reported value for the fission yield of Ba139, that for the iodine was found to be 5.75 × 10−2. A mass of 134 is assigned to the 54 min. I on the basis of Thode's data.

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.

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.

Investigation of the P-Resonance Properties in Slow Neutron Fission of U-235

1992 ◽  
pp. 134-136 ◽  
Author(s):  
A. M. Gagarsky ◽  
S. P. Golosovskaja ◽  
A. B. Laptev ◽  
A. K. Petukhov ◽  
G. A. Petrov ◽  
...  
Keyword(s):  
Slow Neutron ◽  
Neutron Fission ◽  
Resonance Properties

THE ABSOLUTE FISSION YIELDS OF TWENTY-EIGHT MASS CHAINS IN THE THERMAL NEUTRON FISSION OF U235

1955 ◽  
Vol 33 (11) ◽  
pp. 693-706 ◽  
Author(s):  
J. A. Petruska ◽  
H. G. Thode ◽  
R. H. Tomlinson
Keyword(s):  
Fine Structure ◽  
Isotope Dilution ◽  
Yield Curve ◽  
Mass Yield ◽  
Absolute Accuracy ◽  
Neutron Fission ◽  
Thermal Neutron Fission ◽  
The Absolute ◽  
Fission Yields ◽  
Better Than

Twenty-eight absolute fission yields totalling 78% of the heavy and 16% of the light fragments have been determined using the mass spectrometer and isotope dilution techniques. The precision of the values obtained is in most cases better than 2% and the absolute accuracy is estimated to be about 3%. Fine structure in the mass–yield curve is discussed in terms of structural preference and various chain branching mechanisms.

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