Welcome and Introduction

• Konrad Schmidt (Helmholtz-Zentrum Dresden-Rossendorf, Germany)

Room: online

European Summer School on Experimental Nuclear Astrophysics

• Rosario Gianluca Pizzone (Laboratori Nazionali del Sud, Italy)

Room: online Introduction of the biannual school and invitation for the 11th edition June 12 to 19, 2022

Techniques to constrain r-process reaction rates

• Artemis Spyrou (Michigan State University, USA)

Room: online

Moderated questions

• Aurora Tumino (Kore University of Enna, Italy)

Room: online

Astrophysics and unstable nuclei: Indirect method for radioactive ion beam experiments

• Giuseppe Gabriele Rapisarda (University of Catania, Italy)

Room: online

Moderated questions

• Olivier Sorlin (Grand Accélérateur National d'Ions Lourds, France)

Room: online

Actinide-dating stars: Nuclear uncertainties in cosmic age

• Kelsey Lund (North Carolina State University)

Room: online Nuclear cosmochronometry is the process of using known radioactive decays and astronomical spectra as a method of determining the ages of stars on cosmic timescales. Particularly useful are measurements of the long-lived isotopes of the actinides Thorium and Uranium, which are produced via the rapid neutron capture process (r-process). The production of these actinides in r-process simulations is sensitive to the nucleosynthetic conditions in which their production occurs. Beta decay rates are an important component in r-process calculations as they set the timescale on which the r-process occurs and play a role in determining the extent to which heavy nuclei are populated. In this talk, I will discuss theoretical uncertainty in astrophysical conditions for the r-process as well as currently unmeasured beta decay rates and how these uncertainties propagate into age predictions for a selection of r-process enhanced, metal-poor stars.

Moderated questions

• Sara Palmerini (University of Perugia, Italy)

Room: online

Determining neutron-induced reaction cross sections through surrogate reactions at storage rings

• Jacobus Swartz (Centre d'Etudes Nucleaires de Bordeaux Gradignan, France)

Room: online Investigating the interactions of neutrons with unstable nuclei is crucial to our understanding of nuclear astrophysics as it sheds light on the stellar nucleosynthesis of heavy elements. Obtaining accurate cross section data for neutron-induced reactions on these nuclei presents major experimental challenges since both beam and target are radioactive. The NECTAR (NuclEar reaCTions At storage Rings) project aims to solve this problem by using the surrogate-reaction method, where one may indirectly infer the neutron-induced cross sections of short-lived nuclei, in inverse kinematics. A heavy, radioactive nucleus in the beam is to interact with a light, stable nucleus in the target to produce the compound nucleus formed in the neutron-induced reaction of interest via an alternative or surrogate reaction such as transfer or inelastic scattering. This compound nucleus may decay by fission, neutron or gamma-ray emission, and the probabilities for these modes of decay are to be measured as a function of the excitation energy of the compound nucleus. This information is used to constrain model parameters and to inform more accurate predictions of neutron-induced reaction cross sections. The heavy-ion storage rings at GSI/FAIR in Germany present an ideal laboratory for the development of the surrogate reaction method, which still suffers from various target-related issues. The sustained high beam quality, along with the use of an ultra-thin gas-jet target, makes it possible to measure excitation energies and decay probabilities with an unrivalled accuracy. A first Proof-of-Principle experiment is to be performed during the first half of 2022 at the ESR storage ring facility. The 208Pb(p,p’) reaction will be investigated in inverse kinematics with an incident beam of 208Pb at 30 AMeV. Target residues will be measured with a detector telescope inside the reaction chamber, in coincidence with beam residues using double sided silicon strip detectors downstream after a dipole magnet, thus providing decay probabilities for both neutron and gamma-ray emission. After this first pilot experiment, the NECTAR detection setup will be supplemented with fission fragment detectors, thus enabling for fission, neutron and gamma-ray emission probabilities to be measured simultaneously for the first time at this facility. This presentation will focus on the concept and technical development of NECTAR, as well as the preparation for these experiments at the storage rings of GSI/FAIR. This work has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (ERC-Advanced grant NECTAR, grant agreement No 884715).

Moderated questions

• Sara Palmerini (University of Perugia, Italy)

Room: online

Triple radio-frequency quadrupole trap system for measuring neutron capture cross sections of short-lived isotopes

• Heinrich Wilsenach (Justus-Liebig-Universität Gießen)

Room: online One of the current limitations of predicting the nuclear astrophysics r-process abundance is the lack of experimental data on neutron-capture cross-sections of radioactive neutron-rich isotopes. These cross-sections are also invaluable for nuclear reactions and nuclear structure in general. Their measurement is currently considered impossible due to the instability of the targets and projectile. We propose a method to overcome this limitation. We plan to select and store fission fragments in a radio frequency system (coined ‘NG-Trap’), which will form a trapped ‘cloud target’ that will consequently be irradiated by an intense neutron beam. The reacted ions will be mass-selected, identified and counted using a multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS), thus extracting (n,γ) cross sections. This talk will mainly focus on the NG-Trap system that will be developed for the Soreq Applied Research Accelerator Facility (SARAF), currently under construction in Yavne, Israel. We will further present an existing triple radio-frequency quadrupole system, which is presently being set up at Tel-Aviv University for research and development of the cloud target concept, and preliminary estimations of event rates for numerous radioactive target isotopes.

Moderated questions

• Sara Palmerini (University of Perugia, Italy)

Room: online

Round table discussion Room: online Questions that were compiled in the chat during and after lectures and the breakout session will be answered and discussed.