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.

Protactinium, a radioelement with unknown chemistry, is a key element : first actinide for which the 5f orbitals can be involved in chemical bonding, it is also naturally ocurring in envrionment, in the nuclear fuel cycle and also appear in the synthesis of innovative isotopes for medicine. Understanding the chemical behaviour of Pa in these compartments constitutes a great challenge especially since the basic chemistry of this element remains quite blurred ! In this project, we propose to switch to a new paradigm: "predict then experiment". Two main types of properties will be scrutinized, reactivity in terms of equilibrium constants between a set of ligands and protactinium(IV/V) and spectroscopy of protactium compounds. After an extensive methodological study and state-of-the-art theoretical predictions, we will set up prime electromigration, solvent extraction and spectroscopy (high-resolution XANES and laser spectrofluorimetry) experiments aiming at validating/improving the theoretical models and revealing this rare chemistry.

Positron sources are essential to the future e+e-/µ+µ- collider projects (ILC, CLIC, FCC-ee, LEMMA, etc.) with challenging critical requirements of high-beam intensity and low emittance necessary to achieve high luminosity. The intensities required from the positron sources at the future colliders are a few orders of magnitude higher than that delivered by ever existed facilities. Investigations, novel solutions, technological R&D and experimental testing are all mandatory for more robust and reliable designs to meet future needs. The main goal of the INSPIRER project is investigation of the novel types of positron source based on the hybrid scheme with new granular targets and positron capture systems. In particular, the innovative proposal to use a superconducting solenoid as the matching device for capture system is of great interest. Another innovative aspect that will be developed is the Artificial Intelligence global optimization of the positron injector parameters.

In the nuclear field, the components operating in the heart of reactors require materials that can present, in time, good mechanical strength under irradiation and that, most often in an aggressive environment. Currently the 304L is widely used but has limitations and alternative material would be interesting if it had significant gains in: - The decrease in activation at end of life - The increase in corrosion resistance - Reduced unsprung weight to hold in earthquake and weight gain for the onboard reactors. Titanium and its alloys are a good candidate, and are already used by the Russians in the field of propulsion. However, there is very little data to validate this public interest. This project aims to study the behavior of titanium and its alloys by irradiating medium to determine and provide the best possible behavior. The project will: - To study the behavior at the interface fluid-metal, the hydrogen uptake. - Study the effects on mechanical properties of the damage due to irradiation to predict degradation. - Understand the effects of irradiation on alpha and beta phases existing in all titanium alloys. Experimentally, the project proposes to use a limited number of types of radiation, heavy ions, the cyclotron radiation of ARRONAX, to appraise a piece of titanium alloy irradiated with neutrons and already completed by calculation for extrapolate the behavior more intense radiation. The entire study will use 304L steel as a base reference to compare with titanium alloys. Several industrial and academic players differ intervene to gain access to all relevant factors under study, and a large number of characterizations will be conducted for the full view before and after irradiation of the samples tested. If the titanium alloys are attractive, industrial uses will be considered in the internal structure of upper tank, steam generators, packaging containers of fuel new and used, as well as in other applications.

The Rubin-LSST (Large Survey of Space and Time) project is a deep survey of the sky with an 8.40 diameter telescope equipped with a 3.2 billion pixel camera. Starting in 2024, it will map the southern sky for 10 years, with 800 photometric measurements per object, obtained through 6 wide visible bandwidths. This survey will not only allow to measure precisely cosmological parameters, but also to revolutionize the studies of the variable sky. In order to measure the transparency of the atmosphere in real time a spectrograph, equipped with a holographic optical element developed at IJCLab and LPNHE and realized in France, is installed on an auxiliary telescope in operation since early 2021. The process of atmospheric compensation that we want to develop consists in measuring the transmission of the atmosphere with this spectrograph, then to use it to restore estimates of fluxes relative to "standard" atmospheric conditions. This operation will allow the best use of the data from the LSST main telescope. The objective is to reach a photometric accuracy of the order of 0.1%, even under non-stable atmospheric conditions, which would be a remarkable breakthrough: first, the nights qualified as non-photometric would be more usable; second, the improvement of the photometric accuracy would have an effect equivalent to an increase of the collecting area of the main telescope. Benefits are expected in all fields of astronomy, and in particular in cosmology thanks to the very significant improvement of the photometric follow-up of the 100,000 supernovae expected in LSST. The French team has been leading this very high visibility project since its beginning, and the LSST management has delegated to us the responsibility to build on the effort made since 2017 to complete the implementation of the spectrograph and to finalize the photometric compensation procedures related to the atmosphere. To this end, our work program is first to complete the installation, calibration, and performance verification of the auxiliary telescope spectrograph in all possible atmospheric situations, in terms of humidity and aerosol absorption. We also estimate that at least 3 years of sustained effort are still needed to perfect and make reliable the spectra reduction and real-time atmospheric parameter extraction programs, to develop the photometric compensation procedures, to optimize the observing strategy of the spectrograph in synchronism with the main telescope, and to measure and understand the impact of the atmosphere on an annual cycle. Consequently, we first request from the ANR the financing of a post-doctoral fellow for 3 years, in anticipation of the end of a current contract, to allow us to maintain our efforts in these developments. Secondly, to best measure the transparency of the atmosphere, it is essential to have an excellent knowledge of the complete transmission of the instrument consisting of the auxiliary telescope and its camera, as a function of wavelength. This transmission combines the reflectivity of the mirrors, the transmission of the optics and the hologram, and the quantum efficiency of the detector. We therefore need to complete our spectrograph with a device for calibrating the auxiliary telescope, the "travelling CBP" for Collimated Beam Projector, a device derived from a system already used for the StarDICE project, and of which a version has been built for the main LSST telescope. The version to be developed to regularly measure the transmission of the auxiliary telescope requires the acquisition of an intense laser-driven light source coupled to a monochromator, for which we are requesting funding from the ANR.