Speaker
Description
Nuclear level densities (NLD) and photon strength functions (PSF) are essential input parameters for theoretical calculations and evaluations of nuclear reaction data for basic science and a wide range of nuclear applications.
The IAEA Reference Input Parameter Library (RIPL), released in 2009 [1], provided reliable level‑density and photon‑strength‑function models and recommended values widely used in reaction modelling and nuclear data evaluations, forming a foundation for nuclear astrophysics and many nuclear applications. To reflect major advances in experimental techniques, modelling approaches and evaluations over the past decades, the IAEA is coordinating focused research projects that address individual RIPL components.
The CRP on a Photon Strength Function (PSF) reference database [2] produced a comprehensive compilation of experimentally derived strength functions and two recommended global models—one microscopic and one phenomenological—both rigorously validated against PSF and related integral data. Experimental and calculated PSF data are now available through a user-friendly online interface [3]. Follow up activities focus on studying the systematics of the different measured strengths and on performing a data-driven evaluation of the experimental PSFs.
A second CRP, on Updating Nuclear Level Densities for Applications [4], is currently compiling an extensive database of experimentally extracted level densities. The CRP work programme [4] includes re-evaluation of average neutron resonance spacings, development of new global phenomenological and microscopic models, and using theoretical advances to improve our understanding of spin distributions and collective enhancement. All tables, data files, and recommended models will be disseminated across multiple platforms, and a comprehensive final publication will document the full CRP results.
This presentation will provide an overview of both PSF and NLD projects, summarizing achievements so far and highlighting remaining challenges and future needs.
References
[1] R. Capote et al., Nucl. Data Sheets 110 (2009) 3107.
[2] S. Goriely et al., Eur. Phys. J. A (2019) 55:172.
[3] S. Jongile et al., EPJ Web of Conferences 322 (2025) 06005.
[4] S. Hilaire et al., in Summary Report of the 1st Research Coordination Meeting on Nuclear Level Densities, INDC(NDS)-0920, IAEA, September 2025.