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![Results from the upper limit calculation for the 226 Ac cross section for each beam energy. Upper limits are calculated at a 95% confidence level and employ the method described by [Currie, 1968].](profile/Dag-Horn/publication/382308513/figure/tbl3/AS:11431281279052119@1726781039953/Results-from-the-upper-limit-calculation-for-the-226-Ac-cross-section-for-each-beam.png)
Results from the upper limit calculation for the 226 Ac cross section for each beam energy. Upper limits are calculated at a 95% confidence level and employ the method described by [Currie, 1968].
Source publication
Cross sections for production of the medical isotope 225Ac by the 226Ra(p,2n) reaction have not previously been measured in fine steps over the relevant energy region, and no measurements are presently available in the literature for the actinium contaminant isotopes created by the adjacent 226Ra(p,n)226Ac and 226Ra(p,3n)224Ac reactions.
We repor...
Context in source publication
Citations
... Besides these two production routes, another three approaches to the large-scale production have been proposed, all based on 226 Ra targets: photonuclear reaction 226 Ra(γ,n) 225 Ra → 225 Ac, neutron activation 226 Ra(n,2n) 225 Ra → 225 Ac or charged particle induced reactions, in particular 226 Ra(p,2n) 225 Ac that may be implemented on the existing cyclotrons [6]. There are only two published experimental cross sections for the 226 Ra(p,xn) reactions of Apostolidis et al. [7] and Horn et al. [8]. Their data are, however, rather scarce, scattered and in the case of the major radioisotopic impurity, 226 Ac (T ½ = 29.37 h) even entirely missing [7,8]. ...
... There are only two published experimental cross sections for the 226 Ra(p,xn) reactions of Apostolidis et al. [7] and Horn et al. [8]. Their data are, however, rather scarce, scattered and in the case of the major radioisotopic impurity, 226 Ac (T ½ = 29.37 h) even entirely missing [7,8]. It is to be noted that the work of Apostolidis et al. [7] used standard technique of the target and beam parameters measurement similar to our work, while Horn et al. [8] related the activity of the Ac isotopes to the number of beam-target interactions deduced from the measurement of elastic scattering of the protons from the radium target. ...
... Their data are, however, rather scarce, scattered and in the case of the major radioisotopic impurity, 226 Ac (T ½ = 29.37 h) even entirely missing [7,8]. It is to be noted that the work of Apostolidis et al. [7] used standard technique of the target and beam parameters measurement similar to our work, while Horn et al. [8] related the activity of the Ac isotopes to the number of beam-target interactions deduced from the measurement of elastic scattering of the protons from the radium target. ...
... The measured value of 13.9 W/m-K will be used to estimate the thermal behaviour of various target designs. Figure 4 compares the cross section for the reaction 225 Ra(p,2n) 226 Ac as calculated by the Monte Carlo code Fluka [19]- [21] and as measured by Apostolidis et al [22] and Horn et al [23]. The measured cross sections tend to be smaller than the one used by Fluka but they all indicate a peak in the cross section between about 15 and 17 MeV. ...
... This target is described below. [22] (red squares) and as measured by Horn et al [23] (green diamonds) The vertical dashed lines indicate the approximate proton energy range within a 40/60 In/RaCO 3 target for the geometry shown in Figure 5. Figure 5 shows a schematic of the setup used to irradiate the target. The cyclotron vacuum system is terminated with a double Havar window that is cooled by helium. ...
The production of 225Ac using either a proton or electron accelerator requires a target of 226Ra. Radium metal is difficult to work with and so a radium salt, such as radium carbonate, is preferred as a target material. Normally available as a powder, the average density of the powder is low and the thermal conductivity is poor, thus limiting the beam power that can be dissipated in the target. This work proposes the creation of a solid mixture of a radium salt powder with a metal matrix. Although aluminum powder has been used in similar applications, we suggest that indium powder is good choice for the metal matrix in the case of radioactive radium salts. The target can be formed with low die pressure without any need for heating, thus simplifying the hot-cell equipment needed for target preparation. We describe how the solid mixture can be formed, measure its thermal conductivity and compare the value to model estimates. We calculate the yield of 225Ac under different scenarios. Calculations show that the radioactive isotopes of indium produced during the irradiation should not produce significant handling challenges post-irradiation. For the proposed target geometry and beam parameters, thermal modelling indicates that the target temperature will be below the melting point of indium and the heat flux from the surfaces will be manageable. Thermal resistance at the target interfaces is shown to have a large effect on the target temperature. Using indium powder to form the mixture, occupying about 40 % of the target volume, we find that the yield of 225Ac is 80 GBq (2 Ci) for a 10-day irradiation with a 24 MeV, 3 kW proton beam and approximately the same for three milkings of 225Ra after a 10-day irradiation with a 25 MeV, 20 kW electron beam.
