Systematic analysis of mass yield curves in low-energy fission of actinides

1989 ◽  
Vol 40 (5) ◽  
pp. 2144-2153 ◽  
Author(s):  
T. Ohtsuki ◽  
Y. Hamajima ◽  
K. Sueki ◽  
H. Nakahara ◽  
Y. Nagame ◽  
...  
Keyword(s):  
Low Energy ◽  
Mass Yield ◽  
Yield Curves ◽  
Systematic Analysis

Mass yield curves in low-energy proton-induced fission ofU233,U235,U236,Np237,Pu239,Pu242,Pu244,Am241, andAm243

1991 ◽  
Vol 44 (4) ◽  
pp. 1405-1423 ◽  
Author(s):  
T. Ohtsuki ◽  
Y. Nagame ◽  
K. Tsukada ◽  
N. Shinohara ◽  
S. Baba ◽  
...  
Keyword(s):  
Low Energy ◽  
Mass Yield ◽  
Yield Curves ◽  
Energy Proton ◽  
Induced Fission

scholarly journals Fission Product Mass Yield Curves and Their Energy Dependence

1976 ◽  
Vol 29 (3) ◽  
pp. 125 ◽  
Author(s):  
JL Cook ◽  
EK Rose ◽  
GD Trimble
Keyword(s):  
Fission Product ◽  
Saddle Point ◽  
Empirical Analysis ◽  
Energy Dependence ◽  
Cross Sections ◽  
Mass Yield ◽  
Neutron Fission ◽  
Yield Curves ◽  
Nuclear Temperature ◽  
Better Than

It has been found that the mass yield curves for 232Th, 233U, 235U, 238U and 239pU neutron fission can be fitted, with an accuracy of better than 20 %, by the superposition of two pairs of asymmetric gaussian curves and a single symmetric gaussian curve. The parameters of the fit have been investigated as a function of the nuclear temperature at the saddle point of the fissioning compound nucleus, and the widths and positions are found to vary linearly with this temperature. In addition, broad peaks are found in the weights of the gaussians, the weights being related to partial fission cross sections. This empirical analysis has been compared with the predictions of the Nix (1969) model of fission and deficiencies in the existing theory are discussed.

Characteristics of two fission modes

2001 ◽  
Vol 89 (11-12) ◽  
Author(s):  
Y. Nagame ◽  
Y.L. Zhao ◽  
I. Nishinaka ◽  
S. Goto ◽  
D. Kaji ◽  
...  
Keyword(s):  
Spontaneous Fission ◽  
Shell Structures ◽  
Nuclear Deformation ◽  
Mass Yield ◽  
Asymmetric Mode ◽  
Yield Curves ◽  
Wide Range ◽  
Deformation Properties ◽  
Actinide Fission ◽  
Asymmetric Fission

Characteristics of nuclear deformation properties at scission of two fission modes, symmetric and asymmetric, are reviewed. Existence of two kinds of scission configurations associated with the symmetric and asymmetric fission modes is pointed out: elongated and compact configurations. Each symmetric and asymmetric scission property is discussed in terms of shape elongation evaluated from fragment total kinetic energy (TKE). Fragment deformation at scission is also discussed based on neutron multiplicity data. From the systematic study of the scission properties in a wide range of actinide fission, the bimodal fission observed in spontaneous fission (SF) of the heavy actinides is interpreted as the result of the presence of the two fission paths of the ordinary asymmetric mode and a strongly shell-influenced symmetric one. The correlation between the fragment shell structures and the asymmetric mass-yield curves is described.

CUMULATIVE YIELDS OF THE HEAVY FRAGMENTS IN THE THERMAL-NEUTRON FISSION OF 241Pu

1964 ◽  
Vol 42 (11) ◽  
pp. 2063-2079 ◽  
Author(s):  
H. Farrar ◽  
W. B. Clarke ◽  
H. G. Thode ◽  
R. H. Tomlinson
Keyword(s):  
Fine Structure ◽  
Thermal Neutron ◽  
Isotope Dilution ◽  
Yield Curve ◽  
Mass Spectrometric ◽  
Mass Yield ◽  
General Shape ◽  
Neutron Fission ◽  
Yield Curves ◽  
Thermal Neutron Fission

The relative yields of isotopes of xenon, cesium, barium, cerium, neodymium, and samarium formed by the thermal neutron fission of 241Pu have been obtained by mass spectrometric methods. The relative yields of the elements were normalized by means of the isotope dilution and isobaric techniques, and absolute cumulative yields were determined by summing the relative yields to 100%. The curve obtained for 241Pu is compared with other mass–yield curves. The general shape of this mass–yield curve is similar to that for 239Pu; yet the fine structure shows greater similarity to that for 235U thermal-neutron fission.

Sum rules study and a scaling property of fragmentation mass yield curves

1984 ◽  
Vol 138 (5-6) ◽  
pp. 353-356 ◽  
Author(s):  
X. Campi ◽  
J. Desbois ◽  
E. Lipparini
Keyword(s):  
Sum Rules ◽  
Mass Yield ◽  
Yield Curves ◽  
Scaling Property

29.—Fine-structure in the Mass-yield Curve for Binary Fission—A Possible Secondary Effect

1974 ◽  
Vol 71 (4) ◽  
pp. 333-336
Author(s):  
N. Feather
Keyword(s):  
Fine Structure ◽  
Short Range ◽  
Mass Number ◽  
Yield Curve ◽  
Neutron Emission ◽  
Secondary Effect ◽  
Mass Yield ◽  
Yield Curves ◽  
Number Range ◽  
Α Particles

SynopsisThe recent suggestion (Feather 1974) that the short-range α-particles of fission are emitted predominantly from post-neutron-emission fragments in the mass-number range 140 to 145 is shown to have implications in relation to the fine-structure of the mass-yield curve. An examination of the mass-yield curves of Unik et al. (1973) discloses, in many of them, a fine-structure feature of the type predicted.

Relative yields of stable tin isotopes in neutron-induced fission

1969 ◽  
Vol 47 (13) ◽  
pp. 1409-1414 ◽  
Author(s):  
J. R. de Laeter ◽  
H. G. Thode
Keyword(s):  
High Sensitivity ◽  
Smooth Curve ◽  
Natural Uranium ◽  
Tandem Mass ◽  
Mass Yield ◽  
Neutron Fission ◽  
Yield Curves ◽  
Fuel Rod ◽  
Induced Fission ◽  
Symmetric Fission

A tandem mass spectrometer of high sensitivity has been used to measure the relative yields of the six stable isotopes of tin (117Sn, 118Sn, 119Sn, 120Sn, 122Sn, and 124Sn) and the long-lived isotope 126Sn, produced in the thermal- and fast-neutron fission of 233U and in a reactor fuel rod of natural uranium. Samples of the order of 10−9 g of tin were extracted and analyzed to give a range of yields in the region of symmetric fission. The results show that the mass yield curves in the region of symmetric fission covered by the stable tin isotopes are almost identical for the three irradiations. Furthermore, a smooth curve can be drawn through the yield points for the seven isotopes of tin and there is no evidence of "fine structure" or sharp depression in the curves in this region as has been predicted.

scholarly journals Systematic study of proton-induced spallation reactions with the Constrained Molecular Dynamics (CoMD) model

2019 ◽  
Vol 24 ◽  
pp. 42
Author(s):  
A. Assimakopoulou ◽  
G. A. Souliotis ◽  
A. Bonasera ◽  
M. Veselsky
Keyword(s):  
Molecular Dynamics ◽  
Cross Section ◽  
Cross Sections ◽  
Proton Energy ◽  
Fission Cross Section ◽  
Mass Yield ◽  
Yield Curves ◽  
High Energies ◽  
Spallation Reactions ◽  
Before And After

Proton – induced spallation reactions on 238U, 208Pb, 181Ta and 197Au targets at high energies were studied and investigated using the microscopic Contrained Molecular Dynamics (CoMD) model. Total fission cross sections, the ratio fission cross section to residue cross section, mean kinetic energy of fission fragments, mass yield curves and the number of nucleons emitted, before and after scission, as well as the total nucleon multiplicity were calculated using the CoMD model and compared with experimental data from the literature. Some of our calculations showed satisfactory agreement with available experimental data.The calculations of cross sections and the ratio fission cross section to residue cross section as a function of the proton energy gave us the opportunity to estimate observables for unmeasured nuclides.

Preparatory Procedures for Electron Microscopic Analysis at the Molecular Level of Resolution

1978 ◽  
Vol 36 (3) ◽  
pp. 516-520
Author(s):  
F.J. Sjostrand
Keyword(s):  
Electron Microscope ◽  
Molecular Level ◽  
Microscopic Analysis ◽  
Resolving Power ◽  
Cellular Structures ◽  
Electron Microscopic ◽  
Systematic Analysis ◽  
Technical Developments ◽  
Thin Sectioning ◽  
Obvious Reason

In the 1940's and 1950's electron microscopy conferences were attended with everybody interested in learning about the latest technical developments for one very obvious reason. There was the electron microscope with its outstanding performance but nobody could make very much use of it because we were lacking proper techniques to prepare biological specimens. The development of the thin sectioning technique with its perfectioning in 1952 changed the situation and systematic analysis of the structure of cells could now be pursued. Since then electron microscopists have in general become satisfied with the level of resolution at which cellular structures can be analyzed when applying this technique. There has been little interest in trying to push the limit of resolution closer to that determined by the resolving power of the electron microscope.

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