Berlin 2005 – scientific programme
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HK: Physik der Hadronen und Kerne
HK 22: Postersitzung
HK 22.19: Poster
Monday, March 7, 2005, 16:30–18:00, TU MA141
Search for Short-Lived Fission Isomers in light Actinides* — •P.G. Thirolf, D. Habs, R. Hertenberger, H.J. Maier, T. Morgan, O. Schaile, W. Schwerdtfeger, and J. Szerypo — Ludwig-Maximilians-Universität München
Spectroscopic studies of super- and hyperdeformed actinide nuclei offer the
possibility to gain insight into the multiple-humped fission barrier
landscape of these heavy nuclei.
With the identification of deep third minima in 234,236U the
systematics
of fission isomers in light actinides was revisited, especially searching
for short-lived isomers in light uranium isotopes.
Using a geometrical
projection method and solid state nuclear track detectors, we started
an experimental search for their observation. This rather old detection
technique [1] nowadays benefits from an efficient analysis technology
based on a PC-controlled auto-focus microscope and a CCD camera
together with pattern recognition software.
Using the 232Th(α,2n) reaction, evidence was found for a new
fission isomer in 234U with a halflife of 110±10 ps.
The reaction 238U(α,2n) was used for calibration and
normalization.
Excitation functions and absolute prompt and isomeric fission cross
sections
were measured. Also the (3He,3n) reactions on 232Th and 235U
target were studied in a similar way, searching for an isomer in 232U
and
measuring the known isomer in 238Pu for calibration purposes,
respectively. First results will be presented.
[1] V. Metag et al., Nucl. Instr. Meth 114 (1974) 445.
* Supported by the DFG under contract HA 1101/12-1