Formation of medical radioisotopes 111 In, 117m Sn, 124 Sb, and 177 Lu in photonuclear reactions
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CLEI Experiment
Formation of Medical Radioisotopes 111 In, 117mSn, in Photonuclear Reactions
124
Sb, and
177
Lu
A. S. Danagulyan1) , G. H. Hovhannisyan1)* , T. M. Bakhshiyan1), R. H. Avagyan2) , A. E. Avetisyan2) , I. A. Kerobyan2) , and R. K. Dallakyan2) Received November 20, 2014
Abstract—The possibility of the photonuclear production of radioisotopes 111 In, 117m Sn, 124 Sb, and 177 Lu is discussed. Reaction yields were measured by the gamma-activation method. The enriched tin isotopes 112,118 Sn and Te and HfO2 of natural isotopic composition were used as targets. The targets were irradiated at the linear electron accelerator of Alikhanian National Science Laboratory (Yerevan) at the energy of 40 MeV. The experimental results obtained in this way reveal that the yield and purity of radioisotopes 111 In and 117m Sn are acceptable for their production via photonuclear reactions. Reactions proceeding on targets from Te and HfO2 of natural isotopic composition and leading to the formation of 124 Sb and 177 Lu have small yields and are hardly appropriate for the photoproduction of these radioisotopes even in the case of enriched targets. DOI: 10.1134/S1063778815030035
INTRODUCTION At the present time, radioactive isotopes are extensively used for the diagnostics and therapy of various diseases. Therefore, the need for specific radionuclides is quite high. Reactors and cyclotrons are predominantly used in radioisotope production since the cross sections for neutron and proton activation are large. At the same time, accelerators have a number of advantages, such as safety, relatively cheep exploitation, and the formation of smaller amounts of radioactive waste. In the majority of cases, photonuclear reactions have small cross sections in relation to nuclear reactions. For some radionuclides, however, cross sections for photonuclear reactions are commensurate with cross sections for respective reactions involving neutrons and protons. In the case of target irradiation with a bremsstrahlung beam, the bremsstrahlung-photon flux is formed upon the propagation of electrons through a converter target. The yield Y (Eγ max ) of a (γ, x) photonuclear reaction characterized by a threshold Ethr and a cross section σ(Eγ ) is the convolution of the cross sections and the effective photon energy spectrum W (Eγ max , Eγ ) [1]; that is, (1) Y (Eγ max ) 1)
Yerevan State University, Alek Manukyan Str. 1, Yerevan 0025, Republic of Armenia. 2) A.I. Alikhanian National Science Laboratory (Yerevan Physics Institute) (YerPhI), Alikhanian Brothers Str. 2, Yerevan 0036, Republic of Armenia. * E-mail: [email protected]
E γ max
=a
σ(Eγ )W (Eγ max , Eγ )dEγ , Eth
where a is a normalization constant. As a tentative estimate of the potential of photoproduction of one radionuclide or another, it is reasonable to compare the photonuclear-reaction yield with the cross section for a reaction that is used for the industrial production of the radioisotope being considered. The problem of photoproduction of various isotopes has been addressed to
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