Direct reactions are a cornerstone of our understanding of nuclear structure, providing experimental information on the single-particle and collective properties of nuclear states. While neutron transfer reactions revealed a plethora of new information on nuclear structure, the proton transfer reactions are practically stopped, mostly due to the difficulties in implementing 3He targets. Surprisingly, the question of whether the proton shell closures remain stable far from stability or collapse remains open whereas the disappearance of neutron shell closures and the emergence of new sub-shell closures are extensively studied. Also, key reactions for the understanding of the light curve of Type I X-ray bursts could be tackled via (3He,d) measurements. Finally, the long standing question of the role of neutron-proton pairing along the N=Z line could be addressed with (3He,p) neutron-proton transfer. This proposal aims at implementing 3He targets tailored to such measurements. We focus on two types of targets, active and cryogenic, that will increase the thickness of the available implanted 3He targets by at least two orders of magnitude. First, a new cryogenic target cooled down by a pulse tube cryocooler will be designed to be coupled with new generation of Silicon and Germanium arrays. New window material will be investigated and an efficient de-icing protocol will be developed. Second, the active target ACTAR will be converted for using 3He gas and tested under beam conditions. The experimental capaign is foreseen at GANIL in 2026.

We propose the development of a new generation of an integrated ion source system for the production of very pure radioactive ion beams at low energy, including isomeric beams. This ion source is also, in its own right, an experimental tool for laser spectroscopy. The Rare Elements in-Gas Laser Ion Source and Spectroscopy device will be installed at the S3 spectrometer, currently under construction as part of the SPIRAL-2 facility at the GANIL laboratory in Caen. Thus, REGLIS3 will be a source for the production of new and pure radioactive ion beams at low energy as well as a spectroscopic tool to measure nuclear hyperfine interactions, giving access to charge radii, electromagnetic moments and nuclear spins of exotic nuclei so far not studied. It consists of a gas cell in which the heavy-ion beam coming from S3 will stopped and neutralized, coupled to a laser system that assures a selective re-ionisation of the atoms of interest. Ionization can be performed in the gas cell or in the gas jet streaming out of the cell. A radiofrequency quadrupole is added to capture the photo-ions and to guide them to the low-pressure zone thereby achieving good emittance of the produced low-energy beam that will be sent to a standard measurement station. Owing to the unique combination of such a device with the radioactive heavy ion beams from S3, a new realm of unknown isotopes at unusual isospin (N/Z ratio, refered to as exotic isotopes) will become accessible. The scientific goals focus on the study of ground-state properties of the N=Z nuclei up to the doubly-magic 100Sn and those of the very heavy and superheavy elements even beyond fermium. Once routine operation is achieved the beams will be used by a new users community as e.g. decay studies and mass measurements. The goal of the proposal is to develop this new, efficient, and universal source for pure, even isomeric, beams and for pioneering high-resolution laser spectroscopy that will overcome the present experimental constraints to study very exotic nuclei.

Nuclear astrophysics studies the origin of the chemical elements: from the Big Bang, to stellar burning, and to neutron star mergers. ChETEC-INFRA networks the three types of infrastructures that, together, provide the capabilities needed for this quest: astronuclear laboratories supply reaction data, supercomputer facilities perform stellar structure and nucleosynthesis computations, and telescopes and mass spectrometers collect elemental and isotopic abundance data. ChETEC-INFRA will overcome existing barriers to progress: Specifically, we will unify access to nuclear astrophysics research infrastructures using a novel integrated web portal. We will develop improved nuclear reaction targets and detectors, open-source nucleosynthesis software tools, and three-dimensional model atmospheres for stellar spectral analysis based on up to date physics. We will pioneer complementary techniques to address the same science case, and we will link telescopes to nuclear labs and supercomputers. ChETEC-INFRA provides the community with the tools needed to address key questions on solar fusion, neutron capture nucleosynthesis, and explosive stellar processes. In a combined approach designed to facilitate and boost accessibility, synergies and training, the large amount of transnational access provided will enable projects exploiting at least two different types of infrastructures. Within ChETEC-INFRA, data are archived and catalogued for long-term sustainability beyond the end of the project, ranging from evaluated nuclear reaction rates to detailed abundance data for a multitude of stars to tracer nucleosynthesis calculations. ChETEC-INFRA will reach out to PhD students, secondary school students, and to the detector industry. The ChETEC-INFRA community builds on the success of the ChETEC COST Action CA16117 (Chemical Elements as Tracers of the Evolution of the Cosmos). ChETEC-INFRA is networked with the nuclear astrophysics communities in the United States, China, and Japan.