Dresden 2013 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 64: Struktur und Dynamik von Kernen
HK 64.5: Vortrag
Donnerstag, 7. März 2013, 15:15–15:30, HSZ-301
Photofission of 238U induced by a brilliant, quasi-monochromatic, Compton-backscattered γ beam* — •Lorant Csige1,2, D.M. Filipescu3, T. Glodariou3, J. Gulyas4, M. Guenther5, D. Habs5, H.J. Karwowski6, A. Krasznahorkay4, G.C. Rich6, L. Stroe3, O. Tesileanu3, and P.G. Thirolf1 — 1LMU München, Garching, Germany — 2Excellence Cluster Universe, Garching, Germany — 3IFIN-HH, Bucharest, Romania — 4ATOMKI, Debrecen, Hungary — 5MPI for Quantum Optics, Garching, Germany — 6TUNL, Durham, USA
The photofission cross-section of 238U was measured at sub-barrier energies as a function of the γ energy using, for the first time, a monochromatic, high-brilliance, Compton-backscattered γ beam. This prototype experiment was performed at the HIGS γ-beam facility, using the 238U(γ,f) reaction at a beam energy varied between E=4.7-6.0 MeV and with an energy resolution of dE=150-200 keV. Clear indications of predicted resonance structures have been observed at excitation energies of E=5.1 and 5.6 MeV. With the significantly higher intensity of the beam, when comparing to a tagged-photon facility, the cross-section could be measured at deep sub-barrier energies. The triple-humped fission barrier parameters of 238U have been determined by fitting EMPIRE3.1 nuclear reaction code calculations to the experimental photofission cross-section. Our present results on the fission barrier of 238U support a deep third minimum (EIII=3.6 MeV) and a low inner barrier (EA=4.3 MeV).
*supported by the DFG Cluster of Excellence Universe.