Revisiting the U-238 thermal capture cross section and gamma-raymission probabilities from Np-239 decay

The precise value of the thermal capture cross section of238U is uncertain, and evaluated cross sections from various sourcesdiffer by more than their assigned uncertainties. A number of theoriginal publications have been reviewed to assess the discrepant data,corrections were made for more recent standard cross sections andotherconstants, and one new measurement was analyzed. Due to the strongcorrelations in activation measurements, the gamma-ray emissionprobabilities from the beta decay of 239Np were also analyzed. As aresult of the analysis, a value of 2.683 +- 0.012 barns was derived forthe thermal capture cross section of 238U. A new evaluation of thegamma-ray emission probabilities from 239Np decay was alsoundertaken

Analyses of Oxyanion Materials by Prompt Gamma Activation Analysis

Prompt gamma activation analysis (PGAA) has been used to analyze metal ion oxyanion materials that have multiple applications, including medicine, materials, catalysts, and electronics. The significance for the need for accurate, highly sensitive analyses for the materials is discussed in the context of quality control of end products containing the parent element in each material. Applications of the analytical data for input to models and theoretical calculations related to the electronic and other properties of the materials are discussed

A Large Expansion of the HSFY Gene Family in Cattle Shows Dispersion across Yq and Testis-Specific Expression

Heat shock transcription factor, Y-linked (HSFY) is a member of the heat shock transcriptional factor (HSF) family that is found in multiple copies on the Y chromosome and conserved in a number of species. Its function still remains unknown but in humans it is thought to play a role in spermatogenesis. Through real time polymerase chain reaction (PCR) analyses we determined that the HSFY family is largely expanded in cattle (∼70 copies) compared with human (2 functional copies, 4 HSFY-similar copies). Unexpectedly, we found that it does not vary among individual bulls as a copy number variant (CNV). Using fluorescence in situ hybridization (FISH) we found that the copies are dispersed along the long arm of the Y chromosome (Yq). HSFY expression in cattle appears restricted to the testis and its mRNA correlates positively with mRNA markers of spermatogonial and spermatocyte cells (UCHL1 and TRPC2, respectively) which suggests that HSFY is expressed (at least in part) in early germ cells

Gamma Spectrum from Neutron Capture on Tungsten Isotopes

An evaluation of thermal neutron capture on the stable tungsten isotopes is presented, with preliminary results for the compound systems 183;184;185;187W. The evaluation procedure compares the g-ray cross-section data collected at the Budapest reactor, with Monte Carlo simulations of g-ray emission following the thermal neutron-capture process. The statistical-decay code DICEBOX was used for the Monte Carlo simulations. The evaluation yields new gamma rays in 185W and the confirmation of spins in 187W, raising the number of levels below which the level schemes are considered complete, thus increasing the number of levels that can be used in neutron data libraries

Structure and morphology of model polymer electrolyte membranes based on sulfonated syndiotactic-polystyrene in the δ co-crystalline phase resolved by small-angle neutron scattering

Syndiotactic polystyrene (s-PS) is able to form different kinds of co-crystalline phases with guest molecules of different size, shape and property. Several advanced materials have been produced starting from s-PS co-crystalline films. In particular, sulfonated s-PS (s-sPS) can be used as proton-conductive membrane in some fuel cells applications, as it presents high proton conductivity (comparable with Nafion). Besides, it shows a high chemical and thermo-mechanical stability and a low cost. The morphology of different s-PS clathrates and the structural behavior of s-sPS upon hydration can be thoroughly understood by SANS. In fact, exploiting the neutron contrast variation between various hydrogenated and deuterated components of s-PS and s-sPS clathrates, additional and unique information about the distribution of guest molecules in the crystalline and amorphous regions and about the hydrated domains of the polymer were obtained. Moreover, using uni-axially deformed films the occurrence and distribution of scattering features from typical morphologies on specific directions and sectors of detection plan enable an accurate structural study of such complex polymeric systems. We report in the present paper a detailed SANS investigation of s-PS films, starting from their crystallization with guest molecules to the subsequent sulfonation and hydration. FT-IR, neutron PGAA, WAXD and cryo-TEM were used complementary to SANS to check the state of the samples after each step of the treatment process and to obtain additional structural information as support for the understanding of the SANS data. The current experimental analysis has highlighted that the morphology of these polymeric films is characterized by hydrated channels in the bulk amorphous phase alternated to stacks of crystalline lamellae, oriented along the stretching direction

Evidence for Hydrated Channels and Connected Water Clusters in Proton Conductive Membranes Based on Sulfonated Syndiotactic Polystyrene

Evidence for Hydrated Channels and Connected Water Clusters in Proton Conductive Membranes Based on Sulfonated Syndiotactic Polystyren

Hydrated Channels and Connected Water Clusters in Proton Conductive Membranes Based on Sulfonated Syndiotactic Polystyrene

Evidence for Hydrated Channels and Connected Water Clusters in Proton Conductive Membranes Based on Sulfonated Syndiotactic Polystyren

Neutron Capture Gamma-Ray Libraries for Nuclear Applications

The neutron capture reaction is useful in identifying and analyzing the gamma-ray spectrum from an unknown assembly as it gives unambiguous information on its composition. this can be done passively or actively where an external neutron source is used to probe an unknown assembly. There are known capture gamma-ray data gaps in the ENDF libraries used by transport codes for various nuclear applications. The Evaluated Gamma-ray Activation file (EGAF) is a new thermal neutron capture database of discrete line spectra and cross sections for over 260 isotopes that was developed as part of an IAEA Coordinated Research project. EGAF is being used to improve the capture gamma production in ENDF libraries. For medium to heavy nuclei the quasi continuum contribution to the gamma cascades is not experimentally resolved. The continuum contains up to 90% of all the decay energy and is modeled here with the statistical nuclear structure code DICEBOX. This code also provides a consistency check of the level scheme nuclear structure evaluation. The calculated continuum is of sufficient accuracy to include in the ENDF libraries. This analysis also determines new total thermal capture cross sections and provides an improved RIPL database. For higher energy neutron capture there is less experimental data available making benchmarking of the modeling codes more difficult. They are investigating the capture spectra from higher energy neutrons experimentally using surrogate reactions and modeling this with Hauser-Feshbach codes. This can then be used to benchmark CASINO, a version of DICEBOX modified for neutron capture at higher energy. This can be used to simulate spectra from neutron capture at incident neutron energies up to 20 MeV to improve the gamma-ray spectrum in neutron data libraries used for transport modeling of unknown assemblies