DISTRIBUTION OF NUCLEAR CHARGE IN THE PROTON-INDUCED FISSION OF Th 232 : PART II

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Improved radiochernical techniques have been used to study the distribution in mass of the fission f,ragments resulting froin thermal neutron fission in 2 3 9 P~.Disintegration rates atid half-lives were determined by measurement with a 474 gas flow proportional counter. Further identification of the nuclides was obtained by gamma scintillation spectro~netry. The flux intensity during irradiation was monitored by the 6To(n,r)coCo reaction.The absolute fission yields of 89Sr, 90Sr, OIY, 05Zr, 9 9 M~, '03Ru, 1 0 c R~, lo5Rh, 109Pd, l12Pd,

Section: Is Tellz~riz~mmentioning

confidence: 99%

MASS DISTRIBUTION IN THERMAL NEUTRON FISSION OF ²³⁹Pu

Marsden¹,

Yaffe²

1965

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“…The daughter activity obtained in the second extraction was used to find the parent cross section in standard fashion, and the daughter cross section was then determined by means of eq. [2] described below from the daughter activity obtained in the first extraction. The result showed that the cross section of lZ9Cs was about 10 times larger than that of lZ9Ba at this energy.…”

Section: Table I1mentioning

confidence: 99%

“…[2]. In one irradiation, for example, the target was dissolved as soon as possible after the end of irradiation, and in the second an interval of about 1 h was allowed to elapse before dissolution.…”

Section: Table I1mentioning

confidence: 99%

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

Tomita¹,

Yaffe²

1969

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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-toproton (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 Z,, the most probable charge, towards stability with increase in bombardment energy. Values of Z,, -Z, have been compared with those obtained from other fissioning systems, and predictions made for values of Z, in thc fission of systems yet unstudied, e.g. 235U and Z 3 9 P~. In addition Z, 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.

“…A number of studies on nuclear charge dispersion in the fission of heavy-mass targets by protons of energies 20-85 MeV have been reported (1)(2)(3)(4)(5)(6)(7)(8)(9)(10). In all these studies the displacement of the most probable charge, Z,, from the charge, Z,, corresponding to stability for mass A has been measured.…”

Section: Introductionmentioning

confidence: 99%

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

Saha¹,

Tomita²,

Yaffe³

1971

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Independent formation cross sections of Iz9Cs, I3OCs, 13'Cs, 134C~m, 1 3 4 C~m + g , 1 3 6 C~, l3"Ce, and cumulative formation cross sections of 141Ce and 143Ce were obtained when Z35U was caused to fission with protons of energies varying between 20 and 85 MeV. The energies a t 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 ( Z , . ,-2,) 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 Z, 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.