Activation cross-sections of longer-lived products of proton induced nuclear reactions on dysprosium up to 36 MeV
Introduction
A research program is running to study activation cross-sections of proton and deuteron induced reactions mainly for practical applications and to test the presently used theoretical nuclear reaction codes. From a detailed study of the literature it was recognized that data on rare earth elements in most cases are missing. It is well known that many rare earth radionuclides are used in medicine for diagnostic (PET) and, in a larger proportion, for therapeutic (radiopharmaceuticals and brachytherapy) purposes.
In the frame of this systematic study we have investigated the activation cross-sections induced by protons and deuterons on natural dysprosium targets. The part of the study specifically devoted to production of 161Ho, a candidate therapeutic radioisotope, was published separately (Tárkányi et al., 2013a). Here we report on the complete set of activation cross-section data induced by proton irradiation of dysprosium. No earlier experimental data were found in the literature.
Section snippets
Experiment and data evaluation
The general characteristics and procedures for irradiation, activity assessment and data evaluation (including estimation of uncertainties) were similar as in many of our earlier works (Takács et al., 2011, Tárkányi et al., 2012).
The main experimental parameters and the methods of data evaluation for the present study are summarized in Table 1 (Andersen and Ziegler, 1977, Bonardi, 1987, Canberra, 2000, Dityuk et al., 1998, Herman et al., 2007, International-Bureau-of-Weights-and-Measures, 1993,
Cross-sections
The measured cross-sections for the production of 162mHo, 161Ho, 159Ho, 159Dy, 157Dy, 155Dy, 161Tb, 160Tb, 156Tb, 155Tb are shown in Table 3, Table 4 and Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9, Fig. 10, Fig. 11. The figures also show the theoretical results calculated with the ALICE-IPPE and the EMPIRE codes and the values available in the on-line libraries TENDL 2011 and TENDL 2012 in comparison with experimental results of this work. We show both TENDL versions,
Integral yields
The integral yields calculated from spline fits to our experimental excitation functions are shown in Figs. 11 and 12. The integral yields represent so called physical yields i.e. activity instantaneous production rates at 1 μA beam current (Bonardi, 1987). The only literature value found is for 161Ho (Stephens, 2010), which is about 30% lower than our calculated curve. From Fig. 12. It is seen that the produced radio-isotopes form two groups from the point of view of production yield. The
Summary and applications
We present the first experimental cross-sections for the natDy(p,x) 162mHo, 161Ho, 159Ho, 159Dy, 157Dy, 155Dy, 161Tb, 160Tb, 156Tb and 155Tb nuclear reactions up to 36 MeV incident proton energy. Our excitation functions are relative to the natTi(p,n)48V monitor reaction measured simultaneously. The experimental data were compared with the results obtained by the TALYS code reported in the TENDL libraries and with the results of ALICE-IPPE and EMPIRE calculations. The theoretical description,
Acknowledgments
This work was performed in the frame of the HAS-FWO Vlaanderen (Hungary–Belgium) project. The authors acknowledge the support of the research project and of the respective institutions.
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