Studies of charged-particle-induced residual radionuclides production cross-sections using AVF cyclotron for medical applications / Ahmed Rufa'i Usman

Ahmed Rufa'i, Usman (2017) Studies of charged-particle-induced residual radionuclides production cross-sections using AVF cyclotron for medical applications / Ahmed Rufa'i Usman. PhD thesis, University of Malaya.

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Abstract

The charged-particle-induced nuclear reactions by using cyclotrons or accelerators with a moderate energy have become a very vital feature of the modern nuclear medicine. Based on the well-measured excitation functions, the optimum production parameters of the important radionuclides can be easily determined. Realising the importance of excitation functions for the efficient production of radionuclides, a comprehensive study of residual radionuclides production cross-sections was performed using a stacked-foil activation technique combined with offline HPGe γ-ray spectrometry. In the first phase of the study, a 24 MeV deuteron energy was used as the bombarding particles on two separate stacks, both containing nickel (Ni) and titanium (Ti) foils as the main targets metals. In the 2nd phase, a 50.4 MeV alpha-particle beam energy was used as the projectile on a stack containing holmium (Ho), Ti and copper (Cu) foils. The experiments were performed using the AVF cyclotron of RI Beam Factory, Nishina Centre for Accelerator-Based Science, RIKEN, Wako, Saitama, Japan. Deuteron-induced cross-sections of the natNi(d,x)55-58,60Co, 57Ni, 52g,54Mn and 61Cu reactions were measured from the respective threshold energies up to 24 MeV. From the second phase, the excitation functions of the natCu(α,x)66,67Ga,65Zn,57,58,60Co nuclear reactions have been measured in the energy range of 50 MeV down to 3.2 MeV. Similarly, the excitation functions of natT(α,x)43K,43,44m,44g,46-48Sc, 48V and 48,49,51Cr from natural titanium as well as the excitation functions of 165Ho(α,nx)165-168Tm radionuclides from holmium target have also been measured. The accuracy of the measured cross-sections was confirmed by, in addition to the beam current, the simultaneously measured monitor reaction excitation functions of natT(d,x)48V and natT(α,x)51Cr for the first and second phase of the studies, respectively. The results were compared with previous experimental data (if available) and with the theoretical TALYS 1.4 and 1.6 nuclear reaction codes evaluated in the TENDL-2014, 2015, libraries. Present results show reasonable agreement with some of the reported experimental data while a partial agreement is found with the evaluated (theoretical) data. The integral thick target yields (TTY) of 55Co and 56Co radionuclides via deuteron irradiation on nickel have been calculated. From the stack bombarded by the 50.4 MeV alpha beam energy, the present study also calculated the integral thick target yields for 43K,43,44m,44g,46-48Sc, 48V and 48,49,51Cr from the titanium targets. The measured data are useful to reduce the existing discrepancies among the literature, to improve the nuclear reaction model codes and to enrich the experimental database towards various applications. The natNi(d,x)61Cu cross-sections recommended by the IAEA overestimate recent experimental ones, and their upgrade has been proposed. Some of the radionuclides reported in this study have been investigated via their study route for the first, second or third time.

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