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Saint Petersburg, Russia

Badikov S.A.,National Research Nuclear University MEPhI | Chechev V.P.,Khlopin Radium Institute
Applied Radiation and Isotopes

As a rule the evaluated decay data and their uncertainties reflect the current level of consistency of the experimental data as well as its shortage. However, if we assume a priori that the structure of the decay scheme is precisely established, the inclusion of the exact balance relationships in the evaluation procedure leads to lower uncertainties of the recommended data and strong correlations between some of the evaluated parameters. Such a self-consistent decay data evaluation was carried out using the 242Cm alpha decay as an example. © 2013 Elsevier Ltd. Source

Alekseev I.,Saint Petersburg State University | Novikov D.,Khlopin Radium Institute
Applied Radiation and Isotopes

By the use of various modes of Mössbauer spectroscopy after effects of irradiation of metal iron with 12C4+ and 14N5+ ions of medium energies, and alpha-particles and the 208Tl, 208,212Pb, and 216Po recoil from a 228Th-source have been studied. The experimental data obtained in the study enabled various types of external and internal radiation to be compared in regard to the damage they cause, as well as to their effect on the structure-, phase composition- and corrosion resistance properties of metallic iron. Irradiation with 12C4+ and 14N5+ ions is accompanied by both structural disordering of the α-Fe lattice, and the appearance of γ-phase in the bulk metal. This is indicated by a single line which is 2 to 3-fold broadened (as compared to the lines of the magnetic sextet). This is a result of a strong local heating of the lattice in the thermal spike area with a subsequent instant cooling-down and recrystallization of this "molted" area. Irradiation of iron foils with 12C4+- and 14N5+ ions and with recoil nuclei does provoke corrosion processes (the formation of γ-FeOOH) and is accompanied by an intensive oxidation of the metal. © 2013 Elsevier Ltd. Source

The current status of some decay data used in nuclear astrophysics and cosmochronology is presented. The half-life of 79Se has been evaluated as 3. 6(3) × 105 yr. The total energy of non-neutrino radiation released in act of 37Ar decay has been obtained being 2. 709 (16) keV per disintegration. The recommended half-life values of the long-lived radionuclides (T1/2 ≳ 106 yr) of 26Al, 40K, 53Mn, 60Fe, 87Rb, 93Zr, 98Tc, 107Pd, 129I, 135Cs, 146Sm, 176Lu, 182Hf, 187Re, 205Pb, 232Th, 235U, 238U, 244Pu, and 247Cm are given based on the evaluations published until 2010. © 2011 Pleiades Publishing, Ltd. Source

Badikov S.A.,JSC Energy and Industry Analytica | Chechev V.P.,Khlopin Radium Institute
Applied Radiation and Isotopes

A new, Mandel-Paule-type procedure for statistical processing of one-parameter discrepant experimental data is described. The procedure enables one to estimate a contribution of unrecognized experimental errors into the total experimental uncertainty as well as to include it in analysis. A definition of discrepant experimental data for an arbitrary number of measurements is introduced as an accompanying result. In the case of negligible unrecognized experimental errors, the procedure simply reduces to the calculation of the weighted average and its internal uncertainty.The procedure was applied to the statistical analysis of half-life experimental data; Mean half-lives for 20 actinides were calculated and results were compared to the ENSDF and DDEP evaluations. On the whole, the calculated half-lives are consistent with the ENSDF and DDEP evaluations. However, the uncertainties calculated in this work essentially exceed the ENSDF and DDEP evaluations for discrepant experimental data. This effect can be explained by adequately taking into account unrecognized experimental errors. © 2012 Elsevier Ltd. Source

Grudzevich O.T.,RAS Institute of Physics and Power Engineering | Yavshits S.G.,Khlopin Radium Institute
Physics of Atomic Nuclei

The cross sections for the fission of 232Th, 235,238U, 237Np, and 239Pu target nuclei that was induced by 20- to 1000-MeV neutrons and protons were calculated. The respective calculations were based on the multiconfiguration-fission (MCFx) model, which was used to describe three basic stages of the interaction of high-energy nucleons with nuclei: direct processes (intranuclear cascade), equilibration of the emerging compound system, and the decay of the compound nucleus (statistical model). Fission barriers were calculated within the microscopic approach for isotopic chains formed by 15 to 20 nuclei of the required elements. The calculated fission cross sections were compared with available experimental data. It was shown that the input data set and the theoretical model used made it possible to predict satisfactorily cross section for nuclear fission induced by 20- to 1000-MeV nucleons. © 2013 Pleiades Publishing, Ltd. Source

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