A structural evaluation of the tungsten isotopes via thermal neutron capture

Total radiative thermal neutron-capture $\gamma$-ray cross sections for the $^{182,183,184,186}$W isotopes were measured using guided neutron beams from the Budapest Research Reactor to induce prompt and delayed $\gamma$ rays from elemental and isotopically-enriched tungsten targets. These cross sections were determined from the sum of measured $\gamma$-ray cross sections feeding the ground state from low-lying levels below a cutoff energy, E$_{\rm crit}$, where the level scheme is completely known, and continuum $\gamma$ rays from levels above E$_{\rm crit}$, calculated using the Monte Carlo statistical-decay code DICEBOX. The new cross sections determined in this work for the tungsten nuclides are: $\sigma_{0}(^{182}{\rm W}) = 20.5(14)$ b and $\sigma_{11/2^{+}}(^{183}{\rm W}^{m}, 5.2 {\rm s}) = 0.177(18)$ b; $\sigma_{0}(^{183}{\rm W}) = 9.37(38)$ b and $\sigma_{5^{-}}(^{184}{\rm W}^{m}, 8.33 \mu{\rm s}) = 0.0247(55)$ b; $\sigma_{0}(^{184}{\rm W}) = 1.43(10)$ b and $\sigma_{11/2^{+}}(^{185}{\rm W}^{m}, 1.67 {\rm min}) = 0.0062(16)$ b; and, $\sigma_{0}(^{186}{\rm W}) = 33.33(62)$ b and $\sigma_{9/2^{+}}(^{187}{\rm W}^{m}, 1.38 \mu{\rm s}) = 0.400(16)$ b. These results are consistent with earlier measurements in the literature. The $^{186}$W cross section was also independently confirmed from an activation measurement, following the decay of $^{187}$W, yielding values for $\sigma_{0}(^{186}{\rm W})$ that are consistent with our prompt $\gamma$-ray measurement. The cross-section measurements were found to be insensitive to choice of level density or photon strength model, and only weakly dependent on E$_{\rm crit}$. Total radiative-capture widths calculated with DICEBOX showed much greater model dependence, however, the recommended values could be reproduced with selected model choices. The decay schemes for all tungsten isotopes were improved in these analyses.Comment: 25 pages, 15 figures, 15 table

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. Introduction Elemental analyses for a wide array of elements in the Periodic The materials that have been analyzed in the present study represent an eclectic group of elements that are important from a wide number of standpoints. Additionally, in many cases, the counteranions associated with the central elements in the materials can be of extreme importance in the compound's role as synthetic precursors for other materials where the original materials or compounds have really good advantages as starting materials. Beryllium nitrate, for example, can be used as a starting material for the synthesis of beryllium oxide, 1 which is used in an extremely wide variety of applications ranging from sophisticated electronic materials 2 to dopants in gemstones 3 to dental materials

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

Control of sand flies with attractive toxic sugar baits (ATSB) and potential impact on non-target organisms in Morocco

International audienceBackground: The persistence and geographical expansion of leishmaniasis is a major public health problem that requires the development of effective integrated vector management strategies for sand fly control. Moreover, these strategies must be economically and environmentally sustainable approaches that can be modified based on the current knowledge of sand fly vector behavior. The efficacy of using attractive toxic sugar baits (ATSB) for sand fly control and the potential impacts of ATSB on non-target organisms in Morocco was investigated. Methods: Sand fly field experiments were conducted in an agricultural area along the flood plain of the Ourika River. Six study sites (600 m x 600 m); three with ``sugar rich'' (with cactus hedges bearing countless ripe fruits) environments and three with ``sugar poor'' (green vegetation only suitable for plant tissue feeding) environments were selected to evaluate ATSB, containing the toxin, dinotefuran. ATSB applications were made either with bait stations or sprayed on non-flowering vegetation. Control sites were established in both sugar rich and sugar poor environments. Field studies evaluating feeding on vegetation treated with attractive (non-toxic) sugar baits (ASB) by non-target arthropods were conducted at both sites with red stained ASB applied to non-flowering vegetation, flowering vegetation, or on bait stations. Results: At both the sites, a single application of ATSB either applied to vegetation or bait stations significantly reduced densities of both female and male sand flies (Phlebotomus papatasi and P. sergenti) for the five-week trial period. Sand fly populations were reduced by 82.8% and 76.9% at sugar poor sites having ATSB applied to vegetation or presented as a bait station, respectively and by 78.7% and 83.2%, respectively at sugar rich sites. The potential impact of ATSB on non-targets, if applied on green non-flowering vegetation and bait stations, was low for all non-target groups as only 1% and 0.7% were stained with non-toxic bait respectively when monitored after 24 hours. Conclusions: The results of this field study demonstrate ATSB effectively controls both female and male sand flies regardless of competing sugar sources. Furthermore, ATSB applied to foliar vegetation and on bait stations has low non-target impact

Origin of Hungarian indigenous chicken breeds inferred from mitochondrial DNA D-loop sequences

In this study, we assessed the maternal origin of six Hungarian indigenous chicken breeds using mitochondrial DNA information. Sequences of Hungarian chickens were compared with the D-loop chicken sequences annotated in the GenBank and to nine previously described reference haplotypes representing the main haplogroups of chicken. The first 530 bases of the D-loop region were sequenced in 74 chickens of nine populations. Eleven haplotypes (HIC1-HIC11) were observed from 17 variable sites. Three sequences (HIC3, HIC8 and HIC9) of our chickens were found as unique to Hungary when searched against the NCBI GenBank database. Hungarian domestic chicken mtDNA sequences could be assigned into three clades and probably two maternal lineages. Results indicated that 86% of the Hungarian haplotypes are related to the reference sequence that likely originated from the Indian subcontinent, while the minor part of our sequences presumably derive from South East Asia, China and Japan

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

Analysis of fissile materials by high-energy neutron-induced fission decay gamma rays

Thermal neutrons from the Budapest Research Reactor and fast neutrons from the Berkeley Neutron Generator Facility have been used to analyze uranium. It has been shown that both prompt and delayed gamma rays from neutron capture and fission product decay can be used to analyze uranium concentrations and 235U enrichment. Detection of neutrons from the spontaneous fission of 238U has also been demonstrated for uranium analysis. The observation of high-energy gamma rays following the decay of short-lived fission products is a sensitive indication of fissile material, and the ratio of fission product gamma ray intensities can uniquely determine the concentrations of fission isotopes

Determination of the nuclear level densities and radiative strength function for 43 nuclei in the mass interval 28≤A≤200

The determination of nuclear level densities and radiative strength functions is one of the most important tasks in low-energy nuclear physics. Accurate experimental values of these parameters are critical for the study of the fundamental properties of nuclear structure. The step-like structure in the dependence of the level densities ρ on the excitation energy of nuclei Eex is observed in the two-step gamma cascade measurements for nuclei in the 28 ≤ А ≤ 200 mass region. This characteristic structure can be explained only if a co-existence of quasi-particles and phonons, as well as their interaction in a nucleus, are taken into account in the process of gamma-decay. Here we present a new improvement to the Dubna practical model for the determination of nuclear level densities and radiative strength functions. The new practical model guarantees a good description of the available intensities of the two step gamma cascades, comparable to the experimental data accuracy.JRC.G.2-Standards for Nuclear Safety, Security and Safeguard