Calculation of Excitation Function and Thick Target Yield for α+209 Bi Reaction

Abstract

The excitation function of the charged particle-induced reaction plays an important role in basic nuclear physics research, nuclear engineering design and nuclear technology applications, and which is also essential input information required in areas such as accelerator shielding and fusion reactor design, space radiation effects, radiation therapy and biomedical radioisotope production. In the field of tumor therapy, 211At is ideal targeted therapeutic nuclide for generating α-rays, which is prepared by α-particle bombardment of a bismuth target, and therefore the large-scale production of 211At nuclide relies on the information related to the data of 209Bi(α,2n)211At reaction excitation function and the thick target yield of the 211At nuclide. The production of 211At nuclide is accompanied with the production of 210At nuclide (the decaying substrates are highly toxic 210Po nuclides), and it is also necessary to analyze the data of excitation function for the 209Bi(α,3n)210At reaction and the thick target yield of the 210At nuclide for determining whether the prepared 211At product meets the requirements of the subsequent drug labelling. Based on the above background, the experimental data of 209Bi(α,2n)211At and 209Bi(α,3n)210At reaction excitation function in the Experimental Nuclear Reaction Database (EXFOR) were compiled and analyzed. However, there are still divergency in the experimental data of the reaction excitation functions, especially for the 209Bi(α,3n)210At reaction, and the analyzed available experimental data are discontinuous in some energy region. For providing the reasonable and continuous data of the above two reactions, the relevant theoretical calculations were carried out based on the EMPIRE code. Through the comparison between the experimental data and the EMPIRE calculation results, the reasonable forms of optical potential parameters and level density parameters are chosen. With the enhanced generalized superuid model (EGSM) for level density in the EMPIRE code, the evolution data of the excitation functions of the above two reactions are obtained, and both of them are in general agreement with the analyzed experimental data. Based on the evolution data of 209Bi(α,2n)211At reaction excitation function, the thick target yield of the medical radioisotope 211At was calculated, and it is in good agreement with the related experimental data. Besides, the thick target yield of 210At (the parent nucleus of the highly toxic nuclide 210Po) was also studied. And the results show that the thick target yield ratio of 210At to 211At is less than 10-5 at Eα<29.0 MeV, which is lower than the prescribed occupational intake and meets the requirements for 211At subsequent labelling.

Keywords

• charged particle-induced reaction
• data evolution
• excitation function
• thick target yield