The Beta-Disintegration of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Th</mml:mi></mml:mrow><mml:mrow><mml:mn>233</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>

Bunker, M.E.; Langer, Lawrence M.; Moffat, R. J. D.

doi:10.1103/physrev.80.468

Cited by 14 publications

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“…Hence, it is not possible to clearly discriminate against either a 1+ or 2+ assignment although the existing information on second excited states of eveneven nuclei would tend to favor 2+. I N an earlier investigation, 1 it was found that the beta spectrum of Th 233 appeared to have an anomalous shape which was not explainable in terms of the generally accepted theory of beta decay. 2 The momentum distribution exhibited a deficiency of lowenergy electrons which became manifest in that the Fermi-Kurie plot of the data fell below the usual straight line, in the energy region below 600 kev.…”

Section: (-)mentioning

confidence: 89%

Nuclear Decay ofBr84and the Level Scheme inKr84

Johnson

O'Kelley

1957

Phys. Rev.

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The decay properties of fission product Br 84 have been studied by scintillation methods. Its half-life was found to be 31.80±0.08 minutes. Gamma-ray spectra showed gamma rays of energy 0. 27, 0.35, 0.43, 0.47, 0.52, 0.61, 0.74, 0.81, 0.879=1=0.007, 1.01, 1.21, 1.47, 1.57, 1.74, 1.90±0.02, 2.05, 2.17, 2.47=1=0.03, 2.82, 3.03, 3.28, and 3.93±0.03 Mev. Single-crystal and coincidence spectrometry established beta-ray groups at 4.71, 3.83, 2.80, 1.81, 1.39, and possibly 0.83 Mev. From these data a level scheme in Kr 84 has been formulated with excited levels at 0. 88, 1.90, 2.17, 2.36, 2.62, 2.71, 2.91, 3.35, 3.70, 3.91, and 4.18 Mev. The mass difference between the ground state of Br 84 and Kr 84 is represented by the 4.7l-Mev beta ray which includes 32% of the beta-ray transitions.present study was initiated, using scintillation methods to obtain both the beta-and gamma-ray spectra. II. SOURCE PREPARATION AND HALF-LIFE DETERMINATIONThe Br 84 samples used in this study were prepared by neutron irradiation of UO2SO4 in the Oak Ridge Graphite Reactor. After irradiation, the targets were dissolved in dilute HNO3 containing carrier Br~ and I", and following KMn0 4 oxidation, the Br 2 and I2 were extracted into CCI4. After several cycles of selectively reducing the Br 2 with NH 2 OH FECI and extracting the I2, the Brwas precipitated as AgBr.From two separate experiments very closely agreeing half-lives have been determined for Br 84 . In one the sample was mounted 9.3 cm above a 3-inchX 3-inch Nal crystal and the integral gamma-ray decay followed.Here the pulse-height selector was set to discriminate against the low-energy gamma rays of Br 83 which were also present. The resulting decay curve was exponential over about eight half-lives and a least squares analysis of the data gave a half-life value of 31.81 ±0.04 minutes. In a second experiment a twenty-channel analyzer was set to cover the most intense gamma-ray peak (0.879 Mev). By a least squares analysis the peak was found to decay with a half-life of 31.79=1=0.04 minutes. It is felt that an accurate representation of the Br 84 half-life is given by 31.80±0.08 minutes where the quoted deviation is an estimate of the combined standard and systematic errors. This is in agreement with the value 31.6=1=0.2 minutes recently determined by Fix and Schindewolf. 8 III. SINGLE CRYSTAL SPECTROMETER RESULTSThe gamma-ray scintillation spectrometer consisted of a 3-inch X 3-inch cylindrical Nal crystal mounted on a Dumont 6363 photomultiplier tube by the method described by Lazar and Klema. 9 Sources were centered 9.3 cm above the top surface of the crystal. reported a bromine fission product of half-life 30 to 40 minutes. Born and Seelmann-Eggebert 3 assigned the 30-minute bromine activity to mass 84 by the reaction Rb 87 0,o;)Br 84 .The beta spectrum of Br 84 has been studied with a magnetic lens spectrometer by Duffield and Langer, 4 who reported beta groups of 4.679=1=0.010, 3.56, 2.53, and 1.72 Mev, the highest energy group being 40% abundant, having a \ogft value of 7.75,...

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Section: (-)mentioning

confidence: 89%