Speaker
Description
At CERN-ISOLDE, over a thousand radioactive ion beams (RIBs) are generated from over 70 distinct types of target materials using the Isotope Separation Online Method (ISOL). The target material is bombarded with a high-energy proton beam (around 1.4 GeV) and undergoes nuclear reactions that lead to the production and release of artificially created isotopes, which are then ionised and extracted as ion beams.[1] New materials are needed to improve the release and make even more exotic ion beams accessible, with nanomaterials representing a new class of these target materials.
Even if the first nanomaterial to be operated in ISOL facilities was in 1997, and the first submicrometric (SiC) was tested five years later at ISOLDE and the first nanomaterial in 2011 (CaO), implementation of nanometric target materials meeting the criteria for providing high yields; the need for high cross-sections and high numbers, e.g. density of target nuclei for maximum in-target isotope production contrasts with fast and efficient diffusion and effusion processes of porous materials, remains challenging. As an example, a decade ago only three out of five (CaO, TiC, LaCx or UCx @ MWCNT and MWCNT) nanomaterials have proven to show higher radioisotope intensities than standard targets with longer release characteristics.[2] Nevertheless, the by far most used material is the radioactive uranium carbide (UCx). Consequently, nano structurisation of it is of high importance and will have high impact in present and future ISOL facilities. Even if this low-density nano material showed a 10-fold yield increase for many isotopes due to increased diffusion times, chemical reactions could hinder isotopes from being realeased, in addition to avoid sintering at high operation temperatures, generalised a lot of potential for optimisation and future development is still left. Besides this and additonal advantages, like their highly resistance to radiation damage due to their high ratio of grain boundaries to bulk, they also present additional challenges in terms of safety, e.g. due to reactivity (pyrophoricity of nano-UCx), but more general due to not fully known effects in the human body. Because of this many organizations enforce tight regulations which render difficult the research of nanomaterials, e.g. at CERN, nanomaterials research has been halted until the safety requirements are met or it has been demonstrated that the current facilities are safe enough to avoid airborne nanoparticles, which lead to the construction of a completely new laboratory, the NANOLAB to produce and develop nano-actinide target materials. [1]
With the commissioning of this facility at ISOLDE, a laboratory for further investigations into the tailoring of the microstructure of target materials of non-radioactive, not limited to surrogate materials will improve the ability to develop new target materials in addition to the production of nanometric target materials. Furthermore, the separation of the latter from the development area will streamline the production of established and the implementation of newly developed materials under safe yet efficient conditions and shall be presented.
Keywords: nanomaterial development, ion beams, non-radioactive target material, nanotarget development, laboratory
References:
[1] J.P. Ramos, Nucl. Instrum. Meth. B 463 (2020) 201.
[2] J.P. Ramos, et al., Nucl. Instrum. Meth. Phys. Res., Sect. B, 376 (2016), 81.
