The goals and research objectives of the new CRP on Updating Nuclear level Densities for Applications will be presented.
The determination of the nuclear level densities is of particular importance in a large number of nuclear applications. They indeed govern the decay process from the compound nucleus and are mandatory when dealing with capture cross sections. For decades, theoretical estimates of nuclear level densities have relied on phenomenological models whose parameters are fitted to experimental data....
The Oslo method has been applied to a double-digit number of experiments at the Oslo Cyclotron Laboratory (OCL) and other facilities. The method allows for extraction of nuclear level densities (NLD) and 𝛾-ray strength functions (𝛾SF) from excitation tagged 𝛾 spectra. Due to the large number of experiments performed, the nuclear physics group at the University of Oslo has a database of NLD...
I present the extraction of level densities from a fluctuation analysis of high-resolution spectra. In cases where the spectral fluctuations arise from the incoherent overlap of a single class of states with given quantum number $J^\pi$, a connection can be made between the magnitude of the signal in an autocorrelation analysis and the level spacing. This condition is best fulfilled in...
The Uppsala group has been measuring isomeric yields ratios (IYR) from fission for several years now. This work is done in collaboration with the IGISOL group of the University of Jyväskylä. The IYR are obtained using mass measurement techniques (Penning traps and multi-reflection time-of-flight), i.e., the results are not dependent on current information on, e.g., nuclear level schemes....
The nuclear reaction model code CCONE will be used to validate the nuclear level density updated and improved in the CRP. The work plan will be presented.
This report outlines the future research plans for level density studies in the Chinese nuclear reaction model. First, China Nuclear Data Center (CNDC) aims to implement global phenomenological level density models, including the Constant Temperature Fermi Gas model and the Enhanced Generalized Superfluid model, into the Chinese UNF code for nuclear reaction calculations, particularly for...
Minimum requirements for developing NLD for fission.
We will present three research topics related to the theoretical part of our CRP Contract.
The first topic aims to improve the resolved nuclear levels scheme. To this end, we firstly demonstrate that how the discrete levels can influence the nuclear reaction cross sections and astrophysical reaction rates. Such calculations are performed with both Hauser-Feshbach model and Breit-Wigner...
Average resonance spacing and total radiative widths derived from experimental data are key quantities used in many nuclear physics applications, including testing of level density models and normalization of many experiments. The previous compilation of average resonance spacing and radiative width was a part of the RIPL-3 IAEA project about 15 years ago. The way how the compilation was made...
Nuclear level densities (NLD) impact directly many aspects of nuclear data evaluations, from Hauser-Feshbach calculations to
decay spectra. Therefore, accurate description of NLD are essential to ensure reliability of nuclear applications. Despite its
importance, however, proper extraction of NLD as a function of excitation energy, spin and parity from experimental
measurements has...
Knowledge of nuclear level densities remains significantly limited due to the scarcity of experimental data needed to constrain level density models. Current models rely heavily on limited experimental information derived from s-wave neutron resonance spacings. These data are only available within narrow excitation energy and spin ranges, resulting in poorly constrained models.
Alternative...
Nuclear level density (NLD) can be determined through various experimental techniques, including nuclear level counting, neutron capture reactions (via nuclear resonance widths), gamma-ray spectroscopy in the OSLO method, and particle spectroscopy in the fusion evaporation method.
NLD is strongly influenced by nuclear structure effects such as shell corrections, pairing interactions,...
The ELI-NP facility in Romania will consist of two different types of beamlines: The high-power laser system and the high-brilliance $\gamma$-ray beams. Such $\gamma$-ray beams are very selective when used for exciting atomic nuclei, as the narrow bandwidth provides a very well-defined excitation energy window, and usage of polarised photons provides clean spin-parity selectivity for...
