Spallation reactions. A successful interplay between modeling and applications

The spallation reactions are a type of nuclear reaction which occur in space by interaction of the cosmic rays with interstellar bodies. The first spallation reactions induced with an accelerator took place in 1947 at the Berkeley cyclotron (University of California) with 200 MeV deuterons and 400 MeV alpha beams. They highlighted the multiple emission of neutrons and charged particles and the production of a large number of residual nuclei far different from the target nuclei. The same year R. Serber describes the reaction in two steps: a first and fast one with high-energy particle emission leading to an excited remnant nucleus, and a second one, much slower, the de-excitation of the remnant. In 2010 IAEA organized a worskhop to present the results of the most widely used spallation codes within a benchmark of spallation models. If one of the goals was to understand the deficiencies, if any, in each code, one remarkable outcome points out the overall high-quality level of some models and so the great improvements achieved since Serber. Particle transport codes can then rely on such spallation models to treat the reactions between a light particle and an atomic nucleus with energies spanning from few tens of MeV up to some GeV. An overview of the spallation reactions modeling is presented in order to point out the incomparable contribution of models based on basic physics to numerous applications where such reactions occur. Validations or benchmarks, which are necessary steps in the improvement process, are also addressed, as well as the potential future domains of development. Spallation reactions modeling is a representative case of continuous studies aiming at understanding a reaction mechanism and which end up in a powerful tool.Comment: 59 pages, 54 figures, Revie

Identical outcome after autologous or allogeneic genoidentical hematopoietic stem-cell transplantation in first remission of acute myelocytic leukemia carrying inversion 16 or t(8;21): A retrospective study from the European Cooperative Group for Blood and Marrow Transplantation

PURPOSE: Patients with acute myelocytic leukemia carrying inversion 16 (inv16) or t(8;21) have a better initial response to high-dose cytarabine than patients without these chromosomal abnormalities. They presently do not undergo transplantation in first remission (CR1), but there is concern about late relapses. PATIENTS AND METHODS: From 1990 to 2004, 325 adult patients received transplantations in CR1 (159 patients with inv16 and 166 patients with t(8;21), including 35 and 60 patients, respectively, with additional chromosomal abnormalities). Genoidentical allografts were performed in 64 patients with inv16 and 81 patients with t(8;21), and autografts were performed in 95 patients with inv16 and 85 patients with t(8;21). RESULTS: In patients with inv16, after allogeneic and autologous transplantation, the 5-year leukemia-free survival (LFS) rates were 59% and 66% (P = .5), the relapse incidence (RI) rates were 27% and 32% (P = .45), and the transplantation-related mortality (TRM) rates were 14% and 2% (P = .003), respectively. Female patients had a lower RI and a higher LFS. Additional chromosomal abnormalities, compared with no additional abnormalities, were associated with lower RI rate (12% v 34%, respectively; P = .01) and higher 5-year LFS rate (78% v 59%, respectively; P = .04). In patients with t(8;21), after allogeneic and autologous transplantation, the 5-year LFS rates were 60% and 66% (P = .69), the RI rates were 15% and 28% (P = .03), and the TRM rates were 24% and 6% (P = .003), respectively. Younger age and a lower WBC count at diagnosis were associated with a lower TRM and a better LFS. The TRM was lower and the RI was higher in patients with autologous transplantations versus allogeneic transplantations. CONCLUSION: Both autologous and allogeneic transplantation resulted in similar outcomes