Independent Fission Yields and Neutron Emission Probabilities of Short-Lived Halogen Isotopes

Abstract

Halogen independent fission yields / Ρ -valuesAbstract Independent fission yields of ""''Br and 13 '-' 41 [ produced by thermal neutron induced fission of 235 U haVe been determined using a rapid chemical separation procedure based on the formation of volatile methylhalides through recoil reactions. The isotopic charge distributions and the proton odd-even effect are discussed. Using experimental fission yields and previously measured 0-delayed neutron abundances, the neutron emission probabilities, P n , were recalculated. The P n -values are discussed in the framework of a simple semi-empirical systematics.

Half-lives and delayed neutron emission probabilities of short-lived Rb and Cs precursors

“…A log-log plot of this expression should give a straight line with a slope of 6. However, with the available experimental data, all authors [9,12,39] 14.2 ,+ 1.7 [12] In experimental data, 0 P,, calculated with S~p(E), 9 P,, calculated with Sr =const., zx P. from the gross theory (A) with experimental half-lives, 9 P,, from the gross theory (B) with expected half-lives from the gross theory [44] rates 2, are given instead of P,-values, these were transformed to emission probabilities by the expression P,=2,.T1/z/ln2.…”

Independent fission yields of short-lived Br and I isotopes in thermal neutron fission of235U

“…For higher masses the parent contribution drops to a very low percentage. The fission yields reported by Kratz [5] were converted to independent fission yields using the fractional independent fission yields in [5] and the chain yields by Walker [11] and are also presented in Table 1 for comparison with the present values. The agreement is seen to be good.…”

“…On the other hand previous measurements of Br and I fission yields have been reported relative to noble gas nuclides [-4, 5] or as mass yields obtained as weighting factors when averaging charge distributions at various kinetic energies of fission products [6-1. Of these, only in [4] was an on-line isotope separator used with an emanating fission source containing a mixture of uranium oxide and barium stearate, others used either a rapid chemical separation procedure [5] or a recoil spectrometer [6]. Fission yields of 1,0,1411 were reported previously only once, in [5].…”

“…Of these, only in [4] was an on-line isotope separator used with an emanating fission source containing a mixture of uranium oxide and barium stearate, others used either a rapid chemical separation procedure [5] or a recoil spectrometer [6]. Fission yields of 1,0,1411 were reported previously only once, in [5].…”

Yields of Products from Thermal Neutron-Induced Fission of 235U

“…As the cumulative yield of 138 Xe was used the average 6.46+0.04% of values in refs. [19,21,23], and the independent yield was derived by subtracting the contributions from 138 I and 139 I ( Table 17a). The result is 5.78 + 0.15%.…”