Title: Identificaition of the Shape Isomer in 235U
Authors: OBERSTEDT ANDREASOBERSTEDT STEPHANGAWRYS M.KORNILOV Nikolai
Citation: PHYSICAL REVIEW LETTERS vol. 99 p. 042502-1 042502-4
Publisher: AMERICAN PHYSICAL SOC
Publication Year: 2007
JRC Publication N°: JRC37183
ISSN: 0031-9007
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC37183
DOI: 10.1103/PhysRevLett.99.042502
Type: Articles in Journals
Abstract: The shape isomer in 235U has been searched for in a neutron-induced fission experiment on 234U, which was performed at the isomer spectrometer NEPTUNE of the EC-JRC IRMM. A neutron source, with a tunable pulse frequency in the Hz- to kHz-range and its individually adjustable neutron pulse width in connection with an appropriate detector system is the ideal instrument to perform an isomer search, when decay half-lives above 100 µs are expected. From the delayed fission events observed for two different NEPTUNE settings and at mean incident neutron energies En = 0.95 and 1.27 MeV the isomeric fission half-life could be determined to T1/2 = (4.3 +3.0) ms. The corresponding cross-section was determined to sigma if = (10±8) µb. With these results a first experimental confirmation for the existence of a super-deformed shape isomer in odd-uranium isotopes is given for the first time.
JRC Institute:Institute for Reference Materials and Measurements

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