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[en] The so-called non-statistical Gamma.radiation emitted in the asymmetric fission of 252Cf can be interpreted as echoing the repercussions, in the doubly magic core 132Sn, of the cataclysmic transfer of all, or almost all, of its 76 valence nucleons in rearrangement reactions of the diclusteric molecules involved in the process of asymmetric fission
[en] This document has to purpose the bibliographic study of conversion coefficients between the fluence of a neutron source (californium 252) and the dose equivalents in different configurations. The first chapter is devoted to generalities about the neutron dosimetry, then, the different methods used to evaluate the fluence rates and the dose equivalent rates are shown. The second chapter studies the dose coefficients. It presents the conversion coefficients between the neutron fluence and the dose equivalent for a 252 californium source in several configurations. The dose equivalent are studied in the case of 252 cf source moderated by heavy water spheres in different sizes. (N.C.)
[en] In early 1995, the receipt of four sealed californium-252 sources from Oak Ridge National Lab was successfully accomplished by a team comprised of Radiological Engineering, Radiological Operations and Health Physics Instrumentation personnel. A procedure was developed and walked-down by the participants during a Dry Run Evolution. Several special tools were developed during the pre-planning phases of the project which reduced individual and job dose to minimal levels. These included a mobile lifting device for attachment of a transfer ball valve assembly to the undercarriage of the Cannonball Carrier, a transfer tube elbow to ensure proper angle of the source transfer tube, and several tools used during emergency response for remote retrieval and handling of an unshielded source. Lessons were learned in the areas of contamination control, emergency preparedness, and benefits of thorough pre-planning, effectiveness of locally creating and designing special tools to reduce worker dose, and methods of successfully accomplishing source receipt evolutions during extreme or inclement weather
[en] We suggest a paradigm that might allow for a nonanthropic solution to the cosmic coincidence problem of why the density of vacuum energy and matter are nearly equal today. The fact that the half life of uranium 238 is near to the age of the solar system is not considered a coincidence since there are many nuclides with a wide range of half lives implying that there is likely to be some nuclide with a half life near to any given time scale. Likewise it may be that the vacuum field energy causing the universal acceleration today is just one of a large ensemble of scalar field energies, which have dominated the Universe in the past and then faded away. Predictions of the idea include the following: the current density of vacuum energy is decreasing, the ratio of vacuum pressure to vacuum density, w, is changing and not equal to -1, there were likely periods of vacuum domination and acceleration in the past and may be additional periods in the future, and the eventual sum of all scalar field vacuum densities may be zero
[en] Highlights: • The analysis of 239Pu was performed using the SAMMY Code for Neutron Transmission, Capture, and Fission cross-sections in the resolved resonance region up to 2.5 keV. • Due to the difficulties of processing large covariance matrices, the evaluations were performed in the following distinct uncorrelated energy regions: 0.0–1.0 keV, 1.0 keV–2.0 keV, and 2.0 keV–2.5 keV. - Abstract: The analysis of 239Pu was performed using the SAMMY Code for Neutron Transmission, Capture, and Fission cross-sections in the resolved resonance region up to 2.5 keV. Due to the difficulties of processing large covariance matrices, the evaluations were performed in the following distinct uncorrelated energy regions: 0.0–1.0 keV, 1.0 keV–2.0 keV, and 2.0 keV–2.5 keV. By using version 8.0.0 of the SAMMY code, the treatment of large resonance parameter covariance matrices was improved significantly. The aim of this work is to analyze the experimental data using a self-developed experimental nuclear data fitting code FITWR and analyze it with the SAMMY code, then compare the results with Bayes method. Finally, the output results from these methods is processed by the SAMMY code in order to obtain covariance matrix resonance parameters in the energy range from 0 to 2.5 keV. All the computational experiments done for this paper was carried out at IMAN1 Center – Jordan’s National Supercomputing Center (IMAN1).
[en] In this work it is used inter modulated optogalvanic spectroscopy to obtain Doppler-free spectra of two uranium transitions: 5 L6-7 M7, at 5915.4 angstrom, and 5 L6-5 K6, at 6056.8 angstrom. Hollow cathode lamps filled with argon or neon were used. Both transitions were detected for the most abundant 238 U isotope. By analysing the lineshapes of both transitions, obtained with Doppler and Doppler-free resolution. It is determined the inhomogeneous and homogeneous widths, assuming a strong collision regime. The great sensibility, together with a simple detection scheme, makes this technique very attractive in the study of refractory elements like uranium, which can be easily sputtered in the discharge. (author). 16 refs, 4 figs
[en] The proton-neutron symplectic model with dynamical algebra is applied for the simultaneous description of the microscopic structure of the low-lying positive-parity states of the lowest ground, β and γ bands in . For this purpose, the model Hamiltonian is diagonalized in a -coupled basis, restricted to the state space spanned by the fully symmetric irreps. A good description of the energy levels of the three bands under consideration, as well as the enhanced intraband transition strengths between the states of the ground band is obtained without the use of an effective charge. The results obtained show small admixtures from the higher major shells and a highly coherent mixing of different irreps which is manifested by the presence of a good quasi-dynamical symmetry in the microscopic structure of the collective states under consideration.
[en] Caliban is a benchmarked, bare metallic reactor, operated by the Criticality, Neutron Science and Measurement Department. A joint neutron noise measurement week was organized with a team from the LANL in June 2013. Its aim was to perform multiplication measurements from different subcritical configurations, to build an analysis of the uncertainties of this kind of experiments. The first results of this week are presented here. (authors)