Keyword – proton induced nuclear reaction, experimental cross sections
The Coordinated Research Project (The International Atomic Energy Agency), entitled “Therapeutic Radiopharmaceuticals Labelled with New Emerging Radionuclides (67Cu, 186Re, 47Sc)” is focused on production methods of the 67Cu, 186Re and 47Sc radioisotopes as Theranostic Radionuclides for possible radiopharmaceutical development as well as research purposes.
Little information on nat.Ca(p,x) 46, 47, 48Sc reaction in the energy range below 60 MeV could be found in the literature. First our results of the yield of 46, 47, 48Sc in reaction nat.Ca(p,x) were published in the last year.
For the proton bombardments CaCO3 targets of natural isotopic compositions and different thickness were prepared. The CaCO3 targets were made into 12 and 10 mm diameter pellets of different thickness 0.13 - 0.35 g/cm2 thickness. The target pellet was placed between Al, Cu or Cu, Ti monitors. These monitors were used to determine a proton beam flux. Several alternating pellets and foils were placed as stacks inside an Al target holder. The stacked targets were bombarded by 60 MeV protons for about 5 hours. The average beam current was 20 nA. This irradiation was performed at the AIC-144 cyclotron at the Institute for Nuclear Physics Polish Academy of Sciences in Cracow. The incident energy for each target pellet was calculated by the proton energy loss in passing through other targets and monitors.
Production cross sections for 42, 43K, 47Ca, 46, 47, 48Sc have been measured for the nat.Ca(p,x) reactions up to 60 MeV. Measurements of the experimental cross section for the reaction nat.Ca(p,x) are presented as a function of the mean proton energy in the thick target. Cross section reaching a peak of 0.9 mb at around 33 MeV for 46Sc and 0.8 mb at around 12 MeV for 48Sc. Obtained values of energy for above-mentioned Sc radioisotopes are in good agreement with results reported by Michel et al. . Our cross section results are higher by about 20% than cross section data in Michel et al. work . However, direct comparison of obtained experimental cross section values is difficult because irradiated Ca targets had different chemical forms. The optimum energy range for the nat.Ca(p, 2n)47Sc reaction is 24 - 17 MeV with the peak at about 20 MeV for CaCO3 target. The cross section value is about 2 mb.
Acknowledgement: We are pleased to acknowledge the co-operation and help in performing the irradiations of the team of the AIC-144 cyclotron laboratory. This study was partly financed by Ministry of Science and Higher Education of Poland from funding for science in the years 2016–2019 (cofinanced international program) and by IAEA Research Contract No: 20488.
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 R. Misiak, R. Walczak, B. Wąs, M. Bartyzel, J. W. Mietelski, A. Bilewicz “47Sc production development by cyclotron irradiation of 48Ca” Journal of Radioanalytical and Nuclear Chemistry 313 (2017) 429–434