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First astatine-labeled compound shipped in the U.S.
The Department of Energy’s National Isotope Development Center (NIDC) on March 31 announced the successful long-distance shipment in the United States of a biologically active compound labeled with the medical radioisotope astatine-211 (At-211). Because previous shipments have included only the “bare” isotope, the NIDC has described the development as “unleashing medical innovation.”
O. C. Baldonado, R. C. Erdmann
Nuclear Science and Engineering | Volume 37 | Number 1 | July 1969 | Pages 59-65
Technical Paper | doi.org/10.13182/NSE69-A20898
Articles are hosted by Taylor and Francis Online.
The theory of neutron wave propagation through an interface is investigated with the following models: Model A—One-Speed Diffusion Theory, Model B—One-Speed Transport Theory, Model C—Energy-Dependent Diffusion Theory, and Model D—Energy-Dependent Transport Theory. Numerical results for these four models are given. The wave propagation constants α and β, where k = α + iβ, together with α2 - β2 and 2αβ are compared. In addition, the energy-dependent phase shift θ(E, ω) and amplitude ρ(E, ω) are also computed for Models C, D. The propagation constants compare well with one another. The differences between the four theories, although minor, are enhanced by comparing α2 - β2 as a function of frequency. θ(E, ω) and ρ(E, ω) are identical for Models C and D when plotted. A comparison of the discrete waves written in terms of incident, reflected, and transmitted components is also made. It is concluded that the continuum has a sizeable effect close to the interface. Energy and interface effects were seen to be separable from each other for the models studied. A comparison of the discrete amplitudes was made after neglecting continuum terms. The numerical results show that at the interface, the wave amplitude and phase shifts are almost identical for the two diffusion models but differ substantially from the transport models.