Bombardment Energy and Fission Product Yield Pattern for Protons on Natural Uranium and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">U</mml:mi></mml:mrow><mml:mrow><mml:mn>235</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>

Jones, W.H.; Timnick, Andrew.; Paehler, J.H.; Handley, T.H.

doi:10.1103/physrev.99.184

Cited by 27 publications

(7 citation statements)

References 11 publications

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“…3 for common excitation energy E® of the compound nucleus U 236 . The symmetric fission yield has been observed previously to increase exponentially [17][18][19] with energy to 15-MeV excitation and then linearly 18,19 with energy. There is evidence of a slight dip in the symmetric fission yield at the 20-MeV excitation energy onset of (x,2nf) fissions.…”

Section: B Chemistry and Countingmentioning

confidence: 79%

“…1, is relatively large for fissions produced at the 23.43-MeV and approximately 16-MeV excitation energies of first-and second-chance fissions, respectively. However, because of the exponentially de-creasing yields [17][18][19] below about 15-MeV excitation energy, the symmetric fission yield of third-chance fission induced at approximately 8 MeV is relatively very low. The combination of partial cross sections and yields into the combined yields 8 to be greater than unity.…”

Section: Introductionmentioning

confidence: 99%

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Fission Mass Yield Dependence on Angular Momentum

Ford

Leachman

1965

Phys. Rev.

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Fission mass yields from the compound nucleus U 236 have been measured for 19-29-MeV alpha-particleinduced fission of Th 232 and 9-18-MeV neutron-induced fission of U 235 with particular attention to the yields of symmetric fission. Decreases in the symmetric fission yield are seen at the 25-MeV onset of (a,2nf) fission and the corresponding 14-MeV onset of (n,2n'f) fission. Above these energies, the symmetric fission yields are approximately 13% greater for alpha-particle-induced fission than for neutron-induced fission at the same excitation energies. This increase is partially explained by the fission-chance ratio of higher energy fissions relative to fissions of the most de-excited nuclei being greater for alpha particles than for neutrons. Angular-momentum-dependent cross sections for these fissions were calculated, and the use of reasonable values of level densities with a rigid moment of inertia resulted in a calculated effect of about one-half this observed effect. The difference remaining is possibly explained by fissions following direct interactions. Mass yields of 9.1-18.1-MeV neutron-induced fission of Th 232 and 4.7-18.1-MeV neutron-induced fission of U 238 were also measured.

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Section: B Chemistry and Countingmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Fission Mass Yield Dependence on Angular Momentum

Ford

Leachman

1965

Phys. Rev.

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“…the (n,f), the (n,nf), and the (n,2nf) reactions, and from post-fission neutron emission from the fragments. To estimate the approximate contribution towards the mass yields in the symmetric region from each process, the ratios (sla) of symmetric-to-asymmetric yield are plotted against (E,,, -5)-lI2, similar to the correlations given by Jones (40). The contribution due to each process, i.e.…”

Section: Discussionmentioning

confidence: 99%

Cumulative yields in the 14 MeV neutron fission of ²³²Th and ²³⁸U in the symmetric region

Gevaert¹,

Jervis²,

Sharma³

1970

Can. J. Chem.

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The radiochemical yields of molybdenum-99, ruthenium-103 and -105, palladium-109 and -112, silver-11 1 and -113, cadmium-115, and tin-121 and -125 formed in the 14 MeV fission of thorium-232 and uranium-238 have been determined using a low background Geiger-Muller counter, NaI(T1) crystal, and Ge(Li) detector. The absolute mass yield for molybdenum-99 has been obtained using a copper monitor for neutron flux and for the other nuclides using molybdenum-99 as an internal standard. The mass distribution curves derivcd from the chain yields, in the symmetric region show the presence of a third peak in thorium-232, and only the familiar two peaks for uranium-238 in the asymmetric region. By comparison of normalized cumulative mass yields from this study with prompt fission yield data, the average number of prompt neutrons emitted from fission fragments has been obtained as a function of mass in Z 3 8 U + n fission. It appears that there are two regions of enhanced neutron emission in the mass range 103-128, and that the heavy fragments emit more neutrons than the light ones.

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“…[12][13][14][15][16][17][18][19][20][21] Up to about 40 Mev, * Supported in part by the U. S. Atomic Energy Commission. f Part of a thesis to be submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy.…”

Section: Introductionmentioning

confidence: 99%

Fission ofRa226by 11-Mev Protons

Jensen

Fairhall

1958

Phys. Rev.

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The fission of Ra 226 by 11-Mev protons has been studied by using radiochemical techniques. The massyield curve of fission products shows three humps: a narrow hump centered about mass 112, corresponding to a symmetric fission mode, with two humps on either side, corresponding to an asymmetric fission mode. The measured fission yields of fission fragments at the peaks of all three humps are about the same. The heavy-fragment "wing" of the asymmetric portion of the mass-yield curve is very similar in position and shape to the corresponding member of other asymmetric mass-yield curves. The light-fragment "wing" has accordingly shifted to lower mass numbers, continuing the trend observed in the asymmetric fission-yield curves of elements heavier than radium. The central, symmetric-fission hump is of the same width as the narrow, symmetric-fission curve observed for fission of bismuth by 20-Mev deuterons. The cross section for fission of Ra 226 by 11-Mev protons is measured to be 2=blX10~2 7 cm 2 , and drops by a factor of about 60 when the proton energy is degraded to 9 Mev.

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Bombardment Energy and Fission Product Yield Pattern for Protons on Natural Uranium andU235

Cited by 27 publications

References 11 publications

Fission Mass Yield Dependence on Angular Momentum

Fission Mass Yield Dependence on Angular Momentum

Cumulative yields in the 14 MeV neutron fission of ²³²Th and ²³⁸U in the symmetric region

Fission ofRa226by 11-Mev Protons

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Bombardment Energy and Fission Product Yield Pattern for Protons on Natural Uranium andU235

Cited by 27 publications

References 11 publications

Fission Mass Yield Dependence on Angular Momentum

Fission Mass Yield Dependence on Angular Momentum

Cumulative yields in the 14 MeV neutron fission of 232Th and 238U in the symmetric region

Fission ofRa226by 11-Mev Protons

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Product

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Cumulative yields in the 14 MeV neutron fission of ²³²Th and ²³⁸U in the symmetric region