CM on Evaluation of Photon Strength Functions

12 Nov 2025, 09:00 → 14 Nov 2025, 17:00 Europe/Zurich

M0E69 (IAEA, Vienna, Austria)

Paraskevi DIMITRIOU (International Atomic Energy Agency)

The purpose of the meeting is to monitor progress in the evaluation of Photon Strength Function (PSF) data.

Participants will discuss (i) systematics of experimental and theoretical PSF, (ii) new compilations of PSF data and quality indicators, and (iii) the extension of the PSF database and online interface to include model calculations (D1M+QRPA and SMLO).

Evaluation of Photon Strength Function Data 2023

Wednesday 12 November

09:00 → 09:30 Opening

09:30 → 12:30 Presentations I

09:30 Nuclear Data Section PSF - Neutron Capture 2025

Speaker: Jiri Kopecky (JUKO Research)

10:30 Photon strength functions in light nuclei from forward-angle proton scattering

Inelastic proton scattering at several hundred MeV and extreme forward angles has been established as a versatile tool to study photon strength functions in heavy nuclei from low to high excitation energies. I will report on recent extensions of the method to lighter nuclei. While the approach becomes more model-dependent because of the less favorable ratio of Coulomb to nuclear cross sections, such an analysis seems valuable in view of the notoriously scarce and often conflicting total photoabsorption data in light nuclei. Results for $^{58}$Ni, $^{40,48}$Ca and a series of sd-shell nuclei will be discussed. The latter are confronted with large scale shell-model calculations and data-driven artificial neural network predictions.

Speaker: Peter von Neumann-Cosel (Institut für Kernphysik, Technische Universität Darmstadt)

11:30 An update on multi-step cascade spectra results

Info about recently published data from multi-step gamma cascade spectra will be provided.

Speaker: Mr Milan Krtička (Charles University, Prague)

12:30 → 14:00 Lunch break

14:00 → 17:00 Presentations II

15:00 Systematics of characteristics of pygmy dipole resonances in middle and heavy atomic nuclei with neutron excess

The systematics of energies and contribution to the energy-weighted sum rule of dipole gamma transitions of pygmy dipole resonance (PDR) in middle and heavy nuclei with an excess of neutrons are considered. To describe the energy of the PDR, a macroscopic model of Isacker-Nagarajan-Warner [1] was applied with a relative displacement of the densities of the protons of the crust and surface neutrons. Modified expressions for calculating energy with the number of near-surface neutrons in proportion to the thickness of neutron skin according to the Pethick- Ravenhall approach [2] are presented. Analytical expressions for PDR fraction to the energy weighted sum rule for electric dipole transitions (E1 EWSR) are compared with microscopic calculations and experimental data. Simplified expressions for calculating the PDR contributions in E1 EWSR are presented.
[1] P. Van Isacker, M.A. Nagarajan, D.D. Warner, PRC 45(1), R13(1992).
[2] C.J. Pethick, D.G. Ravenhall, NPA, 606(1-2), 173–182(1996).

Speaker: Oleksandr Gorbachenko (Taras Shevchenko National University of Kyiv, Kyiv, Ukraine)

19:00 → 21:00 Dinner

Thursday 13 November

09:30 → 12:30 Presentations III

09:30 Updates from OCL

I will give a presentation of the most recent results from the Oslo group and the current ongoing projects.

Speaker: Vetle Ingeberg (Department of Physics, University of Oslo)

10:00 Comparison of theoretical calculations to Oslo-type experimental data

I will present comparisons between experimental data obtained using the Oslo method and the theoretical calculations available on the database webpage (SMLO and D1M-QRPA). Oslo data were assigned quality indicators based on the quality of the uncertainty analysis performed as well as the availability of external nuclear data used for normalization. Outliers were identified and correlations as function of the nuclear mass and quadrupole deformation will be presented.

Supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contracts No. DE-AC02-05CH11231 and by the US Nuclear Data Program.

Speaker: Thibault Laplace (University of California, Berkeley)

11:00 Update on the compilation and assessment of experimental photon strength function data

I will provide an update on the current photon strength function experimental data compilation and assessment. New data were added for the Oslo Methods, the Ratio and Shape Method, and Nuclear Resonance Fluorescence. Further, a modified approach on how to capture asymmetric and/or total uncertainties has been developed and the file labelling system has been streamlined.

In this presentation I will discuss the assignment of quality indicators, the challenges encountered, and the proposed solutions for the overall maintenance of the database.

Supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contracts No. DE-AC02-05CH11231 and by the US Nuclear Data Program.

Speaker: Kgashane Malatji (University of California Berkeley, Berkeley, CA, USA)

12:30 → 14:00 Lunch break

14:00 → 17:00 PSF database - updates

Friday 14 November

09:00 → 12:30 Recommendations and drafting of report