Speaker
Description
The synthesis of the heaviest known elements is mostly based on irradiation of actinide targets [1,2] with intense heavy-ion beams at energies around the Coulomb barrier, with Ca-48 being a key projectile [3]. Target production relies generally on the molecular plating technique, which was invented five decades ago [4] and is based on the electrochemical deposition of actinides from alcoholic solution at voltages of several hundred volts. Despite the long experience with the method, even basic aspects remain poorly understood [5] and the elucidation of the process [6] and of the composition and structure of MP produced films, as well as the parameters that govern film properties is still ongoing. Given the breadth of superheavy element research at GSI [7] and the importance of actinide targets for many of these studies, we have performed systematic studies of MP produced thin films (e.g., [8]), which shall serve as a basis towards actinide targets with improved properties, including i) higher beam resistance as is needed in light of ever more powerful heavy-ion accelerators coming online in the major superheavy element laboratories, and ii) thicker target layers that allow covering the whole width of excitation functions of the useful fusion-evaporation channels [1].
In my contribution, I will first discuss the production of lanthanide films by MP, which were characterized by a variety of microscopic, spectroscopic, and ion-beam techniques. Combining the results of several methods, MP thin films were shown to consist of a mixture of carbonates and formates. Under irradiation, these films transform into amorphous oxides with embedded carbon clusters [9]. In the second part I will discuss our studies of advance elec-trochemical procedures based on anhydrous electrochemical routes, which allow producing thicker films than MP does [10]. Also these films were characterized before and after irradiation using microscopic [10] as well as spectro-scopic [11] methods.
[1] Ch.E. Düllmann et al., J. Radioanal. Nucl. Chem. 332, 1505 (2023).
[2] B. Lommel et al., Eur. Phys. J. A 59, 14 (2023).
[3] Yu.Ts. Oganessian, V.K. Utyonkov, Nucl. Phys. A 944, 62 (2015).
[4] W. Parker, R. Falk, Nucl. Instrum. Meth. 16, 355 (1962).
[5] E. Artes, Ch.E. Düllmann, C.-C. Meyer, D. Renisch, EPJ Web Conf. 285, 03001 (2023).
[6] A. Vascon et al., Nucl. Instrum. Meth. A 696, 180 (2012).
[7] Ch.E. Düllmann et al., Radiochim. Acta 110, 417 (2022).
[8] E. Artes et al., Radiochim. Acta 113, 779 (2025).
[9] C.-C. Meyer et al., Nucl. Instrum. Meth. A 1075, 170361 (2025).
[10] C.-C. Meyer et al., Radiochim. Acta 111, 801 (2023).
[11] E. Artes et al., Nucl. Instrum. Meth. A 1075, 170403 (2025).