Nuclear charge dispersion of light-mass fission products in the fission of 235U and 238U by medium-energy protons

1970 ◽  
Vol 48 (12) ◽  
pp. 1924-1933 ◽  
Author(s):  
A. H. Khan ◽  
G. B. Saha ◽  
L. Yaffe
Keyword(s):  
Nuclear Charge ◽  
Fission Products ◽  
Mass Region ◽  
Dispersion Curves ◽  
Medium Energy ◽  
Excitation Functions ◽  
Charge Displacement ◽  
Fission Yields ◽  
Dispersion Of Light

Independent fission yields for 90Ym, 90Ym+g, 91Ym, 91Ym+g, and 92Y and cumulative yields for 91Sr, 92Sr, and 93Y in the fission of 235U and 238U by protons of energy from 20–85 MeV have been determined. Excitation functions and charge dispersion curves have been obtained. The most probable charge, Zp, moves closer to stability, ZA, with increasing energy. The values of ZA − Zp for the two fissioning systems are identical, unlike the situation in the heavy-mass region. The values of ZA − Zp for the light- and heavy-mass regions differ considerably, showing that the equal charge displacement hypothesis does not hold even at these moderate energies.

Nuclear Charge Dispersion in the Fission of 235U by Protons of Energy 20–85 MeV

1971 ◽  
Vol 49 (13) ◽  
pp. 2205-2216 ◽  
Author(s):  
G. B. Saha ◽  
I. Tomita ◽  
L. Yaffe
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Nuclear Charge ◽  
Fission Products ◽  
Mass Range ◽  
Dispersion Curves ◽  
Cross Section Data ◽  
Excitation Functions ◽  
Section Data ◽  
Good Agreement

Independent formation cross sections of 129Cs, 130Cs, 131Cs, 134Csm, 134Csm+g, 136Cs, 139Ce, and cumulative formation cross sections of 141Ce and 143Ce were obtained when 235U was caused to fission with protons of energies varying between 20 and 85 MeV. The energies at which the excitation functions reached their maxima were related to the neutron-to-proton ratio of the fission products. These were compared with other fissioning systems. Charge dispersion curves were obtained from the cross section data. The variation of (ZA − Zp) with energy, both in magnitude and in trend, agrees extremely well with predictions made by Saha and Yaffe for nuclides in this mass range. Calculations for Zp show that good agreement is obtained with the unchanged charge division hypothesis. An estimate has been made of the total number of neutrons emitted in fission at these energies.

Isobaric yield distribution in the fission of uranium by medium-energy protons

1967 ◽  
Vol 45 (16) ◽  
pp. 1863-1873 ◽  
Author(s):  
S. S. Parikh ◽  
D. A. Marsden ◽  
N. T. Porile ◽  
L. Yaffe
Keyword(s):  
Fission Product ◽  
Cross Sections ◽  
Proton Energy ◽  
Nuclear Charge ◽  
Dispersion Curves ◽  
Natural Uranium ◽  
Medium Energy ◽  
Excitation Functions ◽  
Yield Distribution

The independent formation cross sections of 139Ba, 139Ce, 141Ce, and 143Ce, and the cumulative formation cross sections of 139Cs, 141Ba, and 143La, produced from the fission of natural uranium by protons of energies 20–85 MeV, have been measured radiochemically. The proton energies at which the excitation functions reach their maxima correlate well with the neutron-to-proton ratio of the fission product. Nuclear charge-dispersion curves exhibit, with increasing proton energy, the behavior previously found by other workers, i.e. broadening and a shift of the most probable nuclear charge towards stability.

Nuclear charge dispersion in the fission of 233U by protons of medium energy

1969 ◽  
Vol 47 (16) ◽  
pp. 2921-2932 ◽  
Author(s):  
I. Tomita ◽  
L. Yaffe
Keyword(s):  
Proton Energy ◽  
Nuclear Charge ◽  
Fission Neutron ◽  
Medium Energy ◽  
Excitation Functions ◽  
Compound Nucleus Formation ◽  
Charge Displacement ◽  
Experimental Values ◽  
Bombardment Energy ◽  
Neutron Evaporation

Independent yields and excitation functions have been determined for the formation of cesium isotopes with masses 129 ≤ A ≤ 138 in the fission of 233U with protons of energies between 20 and 80 MeV. The energies at which the various excitation functions reach their maxima have been compared with those obtained for the same isotopes from fissioning systems with targets of different neutron-to-proton (N/Z) ratios. The neutron-deficient species have a higher probability of being produced at lower energies from targets with lower N/Z ratios. Charge dispersion curves have been obtained and these show the familiar broadening and displacement of Zp, the most probable charge, towards stability with increase in bombardment energy. Values of ZA – Zp have been compared with those obtained from other fissioning systems, and predictions made for values of Zp in the fission of systems yet unstudied, e.g. 235U and 239Pu. In addition Zp values were calculated for 233U fission, assuming compound nucleus formation up to a proton energy of 50 MeV, assuming pre- and post-fission neutron evaporation on the equal charge displacement and unchanged charge division postulates. Experimental values were found to lie between the two predictions.

Nuclear charge dispersion in the fission of 232Th by protons of energy 20–85 MeV

1969 ◽  
Vol 47 (2) ◽  
pp. 301-312 ◽  
Author(s):  
P. P. Benjamin ◽  
D. A. Marsden ◽  
N. T. Porile ◽  
L. Yaffe
Keyword(s):  
Experimental Data ◽  
Charge Distribution ◽  
Fission Fragment ◽  
Mass Number ◽  
Nuclear Charge ◽  
Dispersion Curves ◽  
Charge Displacement

232Th was irradiated with protons of energy 20–85 MeV and the independent yields of 130Cs, 132Cs, 134Csm, 134Csg, 136Cs, 138Cs, 86Rb, and the cumulative yields of 137Cs and 138Xe were measured radio-chemically. Charge dispersion curves were constructed at various energies and, as in previous studies, the broadening with increasing energy and shift of the most probable charge towards stability were observed. The most probable charge of a fission fragment of a given mass number lies closer to the line of β-stability in the case of thorium fission than in uranium. Detailed calculations in an attempt to correlate the experimental data with equal charge displacement (e.c.d.) and unchanged charge displacement (u.c.d.) charge distribution postulates were attempted. The results are not conclusive, lying in between the two, but favoring u.c.d. at the higher energies.

scholarly journals Nuclear charge dispersion studies in the light-mass region formed in the fission of 238U by protons of energy 35–85 MeV

1977 ◽  
Vol 55 (20) ◽  
pp. 3609-3615 ◽  
Author(s):  
J.-L. Galinier ◽  
M. Dikšić ◽  
L. Yaffe
Keyword(s):  
Cross Sections ◽  
Nuclear Charge ◽  
Mass Region ◽  
Dispersion Curves ◽  
Half Maximum ◽  
Complementary Fragment

Cross sections for the independent formation of 76As and 78As, for the partially cumulative formation of 77As and 77Ge, and the cumulative formation of 79As, 78Ge, and 75Ge formed in the fission of 238U by protons of energies 35–85 MeV have been determined. Charge dispersion curves have been obtained. Values of (ZA – Zp) and full-widths at half-maximum of the curves show that the behaviour of these light-mass products is the same as their complementary fragment (A ≈ 152). This is inconsistent with values found at A = 96.

NUCLEAR CHARGE DISPERSION IN THE HIGH-ENERGY FISSION OF URANIUM

1963 ◽  
Vol 41 (5) ◽  
pp. 762-783 ◽  
Author(s):  
J. H. Davies ◽  
L. Yaffe
Keyword(s):  
Cross Sections ◽  
Proton Energy ◽  
Nuclear Charge ◽  
High Energy ◽  
Dispersion Curves ◽  
Natural Uranium ◽  
Incident Proton ◽  
Excitation Functions

The independent formation cross sections of Cs130, Cs132, Cs134, Cs136, Cs138, Rb86, Nb95m, Nb96, and Nb97 produced in the fission of natural uranium by protons have been measured radiochemically at incident proton energies ranging from 10 Mev to 85 Mev. The excitation functions correlate well with those obtained by Friedlander, Friedman, Gordon, and Yaffe (1963). Charge dispersion curves were constructed at 20, 36, 50, 65, and 80 Mev. The curves broaden with increasing proton energy and the most probable charge approaches the line of β-stability. An explanation for both of these effects is given in terms of spallation–fission competition.

scholarly journals Separation of Lanthanide Isotopes from Mixed Fission Product Samples

Separations ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 104
Author(s):  
Leah M. Arrigo ◽  
Jun Jiang ◽  
Zachary S. Finch ◽  
James M. Bowen ◽  
Staci M. Herman ◽  
...  
Keyword(s):  
Fission Product ◽  
Fission Products ◽  
Nuclear Data ◽  
Product Analysis ◽  
Data Production ◽  
Thermal Irradiation ◽  
Nuclear Events ◽  
Lanthanide Separation ◽  
Enriched Uranium ◽  
Fission Yields

The measurement of radioactive fission products from nuclear events has important implications for nuclear data production, environmental monitoring, and nuclear forensics. In a previous paper, the authors reported the optimization of an intra-group lanthanide separation using LN extraction resin from Eichrom Technologies®, Inc. and a nitric acid gradient. In this work, the method was demonstrated for the separation and quantification of multiple short-lived fission product lanthanide isotopes from a fission product sample produced from the thermal irradiation of highly enriched uranium. The separations were performed in parallel in quadruplicate with reproducible results and high decontamination factors for 153Sm, 156Eu, and 161Tb. Based on the results obtained here, the fission yields for 144Ce, 153Sm, 156Eu, and 161Tb are consistent with published fission yields. This work demonstrates the effectiveness of the separations for the intended application of short-lived lanthanide fission product analysis requiring high decontamination factors.

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.

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