Study of the photon strength functions and level densities in the gamma decay following neutron capture on the isotopes 234U, 236U and 238U

The knowledge of photon strength functions (PSF) and level densities (LD) are essential to model nuclear reactions and to obtain information on the gamma flux and intensities relevant for nuclear applications. A number of theoretical models can be employed for this purpose. In the framework of the statistical model, the gamma cascade after a neutron capture reaction depends on the LD and PSF. The capture reactions on U-234, U-236 and U-238 targets measured with the total absorption calorimeter (TAC) at n_TOF (CERN) provide experimental information on gamma multiplicity and on gamma spectra which can be compared to numerical simulations for different PSF and LD models. The dedicated codes DICEBOX and FIFRELIN were used to simulate the gamma cascades while GEANT4 was used for the simulation of the interaction of these gammas with the TAC materials. In this work we have found consistent models and parameters reproducing simultaneously the spectra measured with the TAC, the total radiation width and the s-wave level spacing as deduced from the resolved resonances, for the three uranium isotopes within the same analysis approach.