scholarly journals ABSOLUTE THERMAL NEUTRON FISSION YIELDS OF U233

1960 ◽  
Vol 38 (3) ◽  
pp. 421-438 ◽  
Author(s):  
D. C. Santry ◽  
L. Yaffe
Keyword(s):  
Neutron Flux ◽  
Thermal Neutron ◽  
Flux Monitor ◽  
Neutron Fission ◽  
Neutron Flux Monitor ◽  
Chemical Separations ◽  
Thermal Neutron Fission ◽  
Γ Ray ◽  
The Absolute ◽  
Fission Yields

The absolute fission yields of 22 nuclides formed in the thermal neutron fission of U233 have been measured radiochemically. Disintegration rates were measured by 4π β-proportional counting techniques. The identity of each nuclide was established by chemical separations and decay characteristics as determined by 4π β-counting and γ-ray scintillation spectrometry. The reaction Co59(n, γ)Co60 was used as a neutron flux monitor. Yields were calculated on the basis of [Formula: see text]

THE RATIO OF THE DIRECT TO THE CUMULATIVE YIELD OF 135Xe IN THE THERMAL NEUTRON FISSION OF 233U, 235U, 239Pu, AND 241pu

1966 ◽  
Vol 44 (1) ◽  
pp. 237-246 ◽  
Author(s):  
A. Okazaki ◽  
W. H. Walker ◽  
C. B. Bigham
Keyword(s):  
Neutron Flux ◽  
Thermal Neutron ◽  
Decay Curve ◽  
Time Shift ◽  
Cumulative Yield ◽  
Β Decay ◽  
Neutron Fission ◽  
Short Irradiation ◽  
Thermal Neutron Fission ◽  
Γ Ray

The ratio of the direct to cumulative yields of 135Xe produced in thermal neutron fission has been determined by measuring the growth and decay of this nuclide in irradiated 233U, 235U, 239Pu, and 241Pu. After a short irradiation in a low neutron flux, the amount of 135Xe increases and reaches a maximum at about 11 hours after the end of the irradiation. The direct yield of 135Xe modifies the time this maximum is reached. The ratio of the direct to cumulative yields was determined by measuring the time shift of the growth and decay curve. The amount of 135Xe was measured as a function of time after the end of irradiation by counting the 249-keV γ ray accompanying the β decay of 135Xe with a lithium-drifted germanium-diode spectrometer. The ratio of the direct to the cumulative yield was found to be 0.195 ± 0.016, 0.044 ± 0.017, 0.162 ± 0.025, and 0.070 ± 0.040 for 233U, 235U, 239Pu, and 241Pu fission respectively.

THE THERMAL-NEUTRON FISSION YIELDS OF 229Th

1966 ◽  
Vol 44 (5) ◽  
pp. 1011-1019 ◽  
Author(s):  
J. W. Harvey ◽  
W. B. Clarke ◽  
H. G. Thode ◽  
R. H. Tomlinson
Keyword(s):  
Thermal Neutron ◽  
Isotope Dilution ◽  
Mass Spectrometric ◽  
Neutron Fission ◽  
Thermal Neutron Fission ◽  
Mass Group ◽  
The Absolute ◽  
Fission Yields ◽  
Mass Spectrometric Techniques

The relative cumulative yields for isotopes of the elements krypton, strontium, xenon, cesium, cerium, and neodymium formed in the thermal-neutron fission of 229Th have been determined by mass spectrometric techniques. Normalization of the relative yields by means of the isotope dilution and isobaric techniques has allowed estimates to be made of the absolute cumulative yields of the heavy-mass group by forcing the sum of the yields to total 100%.

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.

CUMULATIVE YIELDS OF LIGHT FRAGMENTS IN U235 THERMAL NEUTRON FISSION

1962 ◽  
Vol 40 (8) ◽  
pp. 1017-1026 ◽  
Author(s):  
H. Farrar ◽  
H. R. Fickel ◽  
R. H. Tomlinson
Keyword(s):  
Thermal Neutron ◽  
Yield Curve ◽  
Mass Spectrometric Study ◽  
Detailed Examination ◽  
Mass Region ◽  
Mass Yield ◽  
Neutron Fission ◽  
Molybdenum Isotopes ◽  
Thermal Neutron Fission ◽  
Fission Yields

A mass spectrometric study of the relative yields of the strontium, yttrium, zirconium, and molybdenum isotopes formed in the thermal neutron fission of U235 has made possible a detailed examination of structure of the light mass region of the mass–yield curve. The relative yields of this work have been normalized to 5.77% for Sr90, and when literature and extrapolated values are taken for the remaining chains, the fission yields total 100.8%.

THE FISSION YIELDS OF THE CESIUM ISOTOPES FORMED IN THE THERMAL NEUTRON FISSION OF U235 AND THE NEUTRON ABSORPTION CROSS SECTION OF Xe135

1955 ◽  
Vol 33 (11) ◽  
pp. 640-649 ◽  
Author(s):  
J. A. Petruska ◽  
E. A. Melaika ◽  
R. H. Tomlinson
Keyword(s):  
Thermal Neutron ◽  
Cross Section ◽  
Isotope Dilution ◽  
Absorption Cross Section ◽  
Neutron Absorption ◽  
Absorption Cross ◽  
Neutron Fission ◽  
Thermal Neutron Fission ◽  
Fission Yields ◽  
Neutron Absorption Cross Section

The absolute fission yields of the cesium isotopes occurring in the thermal neutron fission of U235 have been determined with a mass spectrometer using isotope dilution techniques. Values of 6.59%, 6.41%, and 6.15% have been obtained for the yields of Cs133, Cs135, and Cs137 respectively. The neutron absorption cross section of Xe135 has also been measured to be 866 times greater than that of B10 for a Maxwellian distribution of neutron velocities corresponding to a neutron temperature of 57 °C. This ratio gives a thermal neutron absorption cross section of 3.47 × 106 barns for Xe135 assuming it is a 1/ν detector.

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