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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.”
B. Rocca-Volmerange
Nuclear Science and Engineering | Volume 64 | Number 3 | November 1977 | Pages 779-784
Technical Note | doi.org/10.13182/NSE77-A27107
Articles are hosted by Taylor and Francis Online.
This Note expands on a previously communicated synthetic slowing down model to determine the neutron spectra in fast reactors. Based on a polynomial approximation, the model accuracy increases with the order of the expansion. It is, in fact, a generalization to N terms of the one-term classical slowing down models such as those of Fermi, Wigner, and Greuling-Goertzel. Equivalent to the classical and synthetic expression of our QN model, this Note proposes a determination of a “differential” expression of the model, allowing the calculation of a set of functions approximating the kernel Σs(u′ → u). To be used in reactor codes, the spectrum determination has to he associated to a spatial resolution; the second part of this Note is devoted to the adaptation of the QN method to the collision probability approximation or the calculation of a spatial Green's function, to obtain a flux (r,E). The applications in the isotropic collision approximation can be extended to the linearly anisotropic approximation, and various results that demonstrate the validity of the method are given.