Molecular Plating Of Actinium Targets For Superheavynuclear Research

The synthesis and chemical properties of superheavy nuclei have been one of the most challenging frontiers in radiation chemistry and nuclear physics.The research of superheavy nuclei is moving in heavier,and the experiment of synthesizing superheavy nuclides is more difficult.In order to carry out the superheavy nuclear research in SHANS（Spectrometer for Heavy Atoms and Nuclear Structure）and better use of heavy ion beams,heavy element targets that can withstand high current heavy-ion beam bombardment and suit for the rotation-target system in SHANS need to be prepared.The preparation actinide targets is one of the key technology in the superheavy nuclear research.In this thesis,the preparation of actinide targets by molecules plating has been studied,which mainly includes the following:1)The study on the preparation of large area fan-shaped ²³²Th target.According to the characteristics of the rotation-target system in SHANS,a new fan-shaped electrodeposition cell was constructed.The preparation conditions for the fan-shaped ²³²Th target were studied.The thorium targets were prepared and have been successfully used in the experiments of heavy ion nuclear reaction on SHANS.2)By scanning electron microscopy（SEM）,energy dispersive X-ray spectrometer（EDS）and X-ray fluorescence spectrometry（XRF）,the microstructure and chemical composition of thorium targets before and after the irradiation were compared.The stability and fastness of the target were verified.3)The study on the preparation of a ²⁴³Am target on titanium backing.Because the neodymium is similar to Americium in ionic radius and chemical properties,was used to study the preparation conditions for molecular plating of Am target.The preparation of ²⁴³Am target on titanium backing was studied,and the technology of preparing americium target on high melting point target backing was mastered.Experiments show that the large-area fan-shaped ²³²Th targets prepared by molecular plating are compact,firm and uniform,and the purity is high,which satisfy the requirements of the rotation-target system in SHANS.These targets also meet the requirements of good performance on the irradiation and thermal stability for the high-current heavy ion beams in the superheavy nuclear experiments.A compact,firm and uniform ²⁴³Am target on titanium backing was also prepared by using molecular plating.In summary,molecular plating is an important technique for the preparation of actinide targets to be used in surperheavy nuclear experiments and the actinide targets can be prepared simply and quickly for the SHANS.