scholarly journals Yields of products in the spontaneous fission of 252Cf by direct γ-ray spectroscopy

1983 ◽  
Vol 61 (4) ◽  
pp. 649-651 ◽  
Author(s):  
L. Toppare ◽  
H. N. Erten ◽  
N. K. Aras
Keyword(s):  
Fine Structure ◽  
Thermal Neutron ◽  
Spontaneous Fission ◽  
Graphical Method ◽  
Spectroscopy Technique ◽  
Neutron Fission ◽  
Fragment Mass ◽  
Thermal Neutron Fission ◽  
Γ Ray

Yields of products both in the light and heavy sides in the spontaneous fission of 252Cf were measured by direct γ-ray spectroscopy technique. By suitably choosing collection, cooling, and counting times, it was possible to observe products with half-lives between 1 min and 1 h. A definite fine structure, as observed in the case of thermal neutron fission of 235U and 239Pu, was not observed. A graphical method was utilized to obtain the number of neutrons as a function of fragment mass using cumulative chain yields.

TIME-OF-FLIGHT FISSION STUDIES ON U233, U235 AND Pu239

1962 ◽  
Vol 40 (11) ◽  
pp. 1626-1663 ◽  
Author(s):  
J. C. D. Milton ◽  
J. S. Fraser
Keyword(s):  
Fine Structure ◽  
Kinetic Energy ◽  
Excitation Energy ◽  
Thermal Neutron ◽  
Time Of Flight ◽  
Neutron Fission ◽  
Thermal Neutron Fission ◽  
The Mean ◽  
New Feature ◽  
Symmetric Fission

The prompt mass and kinetic energy distributions resulting from the thermal neutron fission of U233, U235, and Pu239 have been reinvestigated using time-of-flight methods to measure simultaneously the velocities of the fragment pairs. A new feature shown by the present work is the existence of fine structure in the prompt mass yields. This fine structure is most pronounced at high total kinetic energies where the fragments have little excitation energy and may be associated with irregularities in the energy release as a function of mass. The fine structure is most noticeable in U235 and least in Pu239; the fragments of U235 have the lowest average excitation and those of Pu239, the highest. Another feature, which is confirmed by this work, is the large drop in total kinetic energy when the fragments are near symmetry. This decrease is about 35 Mev and is consistent either with a picture in which the nucleus with 50 protons is especially preferred or with one in which fragments at symmetric fission have an abnormally high excitation energy and a consequent large number of neutrons. The mean kinetic energies for thermal neutron fission of U233, U235, and Pu239 were found to be 167.6, 168.3, and 175.0 Mev with an error of ± 1.7 Mev.

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.

THE CUMULATIVE FISSION YIELDS OF LIGHT MASS FRAGMENTS IN THE THERMAL NEUTRON FISSION OF Pu239

1959 ◽  
Vol 37 (8) ◽  
pp. 916-925 ◽  
Author(s):  
H. R. Fickel ◽  
R. H. Tomlinson
Keyword(s):  
Fission Product ◽  
Thermal Neutron ◽  
Mass Spectrometer ◽  
Isotope Dilution ◽  
Light Fragment ◽  
Neutron Fission ◽  
Fragment Mass ◽  
Thermal Neutron Fission ◽  
Fission Yields

The relative cumulative yields of 19 light mass fragments of rubidium, strontium, yttrium, zirconium, molybdenum, and ruthenium formed in the thermal neutron fission of Pu239 have been determined with a mass spectrometer using the isotope dilution technique.The yields of the fission product isotopes of these elements, together with the previously published relative yields of three krypton isotopes, have made possible the determination of the absolute yields of 22 light fragment mass chains.

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.

scholarly journals Prompt Neutrons From 236U Fission Fragments

1971 ◽  
Vol 24 (4) ◽  
pp. 821 ◽  
Author(s):  
JW Boldeman ◽  
AR de L Musgrove ◽  
RL Walsh
Keyword(s):  
Kinetic Energy ◽  
Thermal Neutron ◽  
Neutron Emission ◽  
Total Kinetic Energy ◽  
Counting Method ◽  
Neutron Fission ◽  
Fragment Mass ◽  
Fission Fragments ◽  
Thermal Neutron Fission ◽  
The Mean

Measurements have been made of prompt neutron emission in the thermal neutron fission of 235 U and the mean neutron emission per fragment has been obtained for particular values of the fragment mass and total kinetic energy. A direct neutron counting method was employed and a comparison is made with data from previous experiments of this type.

Independent Yields of Mass-135 Xenons in the Thermal Neutron Fission of 233U, 235U,239Pu, and 241Pu

1971 ◽  
Vol 49 (7) ◽  
pp. 785-803 ◽  
Author(s):  
R. C. Hawkings ◽  
W. J. Edwards ◽  
W. J. Olmstead
Keyword(s):  
Fission Product ◽  
Thermal Neutron ◽  
Rare Gas ◽  
Neutron Fission ◽  
Thermal Neutron Fission ◽  
Γ Ray ◽  
Gas Fractions

The ratio of the independent yield of 135Xe to the cumulative chain yield of 135I in thermal neutron fission of 233U, 235U, 239Pu, and 241Pu has been measured using radiochemical techniques. 135Xe and 135Xem were recovered quantitatively after short irradiations and compared with 135Xe grown from 135I in the same sample. Corrections were applied for interference from other fission-product gases in the NaI(Tl) γ-ray spectrometry of the rare gas fractions. If the independent yield for 135Xem is assumed to be zero, the ratio of the independent yield of 135Xe to the cumulative chain yield to 135I is found to be 0.2790 ± 0.0069 for 233U, 0.0357 ± 0.0019 for 235U, 0.1782 ± 0.0023 for 239Pu, and 0.0332 ± 0.0016 for 241Pu.The ratio of the cumulative chain yield to 135I for thermal fission of 239Pu to that for 241Pu was found to be 0.966 ± 0.054.

Ranges of shielded nuclides from thermal-neutron fission

1969 ◽  
Vol 47 (21) ◽  
pp. 2371-2385 ◽  
Author(s):  
H. Nakahara ◽  
J. W. Harvey ◽  
G. E. Gordon
Keyword(s):  
Monte Carlo ◽  
Thermal Neutron ◽  
Neutron Emission ◽  
Fission Products ◽  
Energy Transformation ◽  
Neutron Fission ◽  
Monte Carlo Calculations ◽  
Neighboring Chain ◽  
Thermal Neutron Fission ◽  
Γ Ray

Average ranges in Al of shielded nuclides 86Rb and 136Cs and several chain-yield species from thermal-neutron fission of 233U and 235U have been measured. The values obtained (in mg/cm2 Al) are, for 233U: 86Rb, 3.88 ± 0.04; 136CS, 2.80 ± 0.01; and for 235U: 86Rb, 3.76 ± 0.03; 136Cs, 2.81 ± 0.01. A range–energy transformation was used to determine average kinetic energies [Formula: see text] of the secondary fragments. In agreement with previous work, the shielded nuclides are found to have smaller [Formula: see text] values than neighboring chain-yield species. The deficits of [Formula: see text] are, for 233U, 4 and 8 MeV, and for 235U, 8 and 10 MeV, respectively, for 86Rb and 136Cs. Most of the range experiments were done with the thick-catcher method followed by conventional radiochemical treatment of the catcher foils. Ranges of 20 products from 233U were determined in preliminary experiments in which gross γ-ray spectra of fission products in the catcher foils were observed with a Ge(Li) detector. The kinetic-energy deficits of the shielded species are interpreted by Monte Carlo calculations of prompt-neutron emission.

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