Search results for "Absorption"
showing 10 items of 2701 documents
The role of yttrium and titanium during the development of ODS ferritic steels obtained through the STARS route: TEM and XAS study
2018
Abstract Oxide Dispersion Strengthened Ferritic Steels (ODS FS) are candidate materials for structural components in future fusion reactors. Their high strength and creep resistance at elevated temperatures and their good resistance to neutron radiation damage is obtained through extremely fine microstructures containing a high density of nanometric precipitates, generally yttrium and titanium oxides. This work shows transmission electron microscopy (TEM) and extended X-ray absorption fine structure (EXAFS) characterization of Fe-14Cr-2W-0.3Ti-0.24Y ODS FS obtained by the STARS route (Surface Treatment of gas Atomized powder followed by Reactive Synthesis), an alternative method to obtain O…
Influence of the manufacturing process on the radiation sensitivity of fluorine-doped silica-based optical fibers
2011
International audience; In this work, we analyze the origins of the observed differences between the radiation sensitivities of fluorine-doped optical fibers made with different fabrication processes. We used several experimental techniques, coupling in situ radiation-induced absorption measurements with post mortem confocal microscopy luminescence measurements. Our data showed that the silica intrinsic defects are generated both from precursor sites and from strained regular Si-O-Si linkages. Our work also provides evidence for the preponderant role of the chlorine in determining the optical losses at about 3.5 eV. The results show that the manufacturing process of these fibers strongly af…
Effect of annealing on Zn1−xCoxO thin films prepared by electrodeposition
2009
Polycrystalline thin films of Zn"1"-"xCo"xO with different cobalt (Co) content were grown on indium tin oxide (ITO) substrates by cathodic electrodeposition technique and subsequently annealed in air at 400^oC. The effect of annealing in their structural, optical and chemical properties has been characterized by X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Raman scattering and optical spectroscopy. Our measurements indicate that moderate annealing increases the crystal quality of the films. The films are highly transparent in the visible range and evidence an increase of the band gap and of the intensity of three typical Co absorptio…
Description of πp→Δ(1232)π and πp→Δ(1232)ρ(770) reaction proceeding via baryon exchange mechanism
1991
We analyze the available experimental data on the backward production processes πN→Δπ and πN→ Δπ in the framework of the strong-cut Reggeized absorption model, which is based on the exchange of the baryon Regge trajectoriesNα and Δδ with the associated cuts. The model describes rather well the data on the differential cross sections at incident π momenta ranging from 2.15 to 20 GeV/c. An essential contribution of Δδ exchange even at small energies (Elab of the order of a few GeV) is found. A model-independent analysis of data confirms this fenomena.
Total Absorption Spectroscopy
2018
Some advances in science come when a new technique is available. There are many examples in the history of science. The advances usually provide the opportunity to see what was hidden to the well-e...
Reactor Decay Heat inPu239: Solving theγDiscrepancy in the 4–3000-s Cooling Period
2010
The {beta} feeding probability of {sup 102,104,105,106,107}Tc, {sup 105}Mo, and {sup 101}Nb nuclei, which are important contributors to the decay heat in nuclear reactors, has been measured using the total absorption technique. We have coupled for the first time a total absorption spectrometer to a Penning trap in order to obtain sources of very high isobaric purity. Our results solve a significant part of a long-standing discrepancy in the {gamma} component of the decay heat for {sup 239}Pu in the 4-3000 s range.
Total photoabsorption cross sections forH1,H2, andHe3from 200 to 800 MeV
1996
The total photoabsorption cross sections for $^{1}\mathrm{H}$, $^{2}\mathrm{H}$, and $^{3}\mathrm{He}$ have been measured for incident photon energies ranging from 200 to 800 MeV. The $^{3}\mathrm{He}$ data are the first for this nucleus. By using the large acceptance detector DAPHNE in conjunction with the tagged photon beam facility of the MAMI accelerator in Mainz, cross sections of high precision have been obtained. The results show clearly the changes in the nucleon resonances in going from $^{1}\mathrm{H}$ to $^{3}\mathrm{He}$. In particular, for the ${\mathit{D}}_{13}$ region the behavior for $^{3}\mathrm{He}$ is intermediate between that for $^{1}\mathrm{H}$, $^{2}\mathrm{H}$, and h…
Three-nucleon mechanisms in photoreactions
2002
The $^{12}$C$(\gamma,ppn)$ reaction has been measured for E$_{\gamma}$=150-800 MeV in the first study of this reaction in a target heavier than $^3$He. The experimental data are compared to a microscopic many body calculation. The model, which predicts that the largest contribution to the reaction arises from final state interactions following an initial pion production process, overestimates the measured cross sections and there are strong indications that the overestimate arises in this two-step process. The selection of suitable kinematic conditions strongly suppresses this two-step contribution leaving cross sections in which up to half the yield is predicted to arise from the absorptio…
Systematics of Gamow-Teller beta decay “Southeast” of 100Sn
2010
The energy centroids and integrated strengths of Gamow-Teller transitions in the $ \beta^{+}_{}$ and electron-capture decay are analyzed for nuclei whose proton number Z and neutron number N are restricted to 44 $ \leq$ Z $ \leq$ 50 and 50 $ \leq$ N $ \leq$ 58 . The analysis is based on data measured both with high-resolution $ \gamma$ -ray spectrometry and total $ \gamma$ -ray absorption techniques. The dependence of the considered quantities on the relative neutron excess are established after taking into account the effects due to the Coulomb interaction and mean-field level occupancies. An extrapolation of this dependence to the lightest known tin isotopes is used to estimate the decay …
Beta decay studies with the total absorption technique: past, present and future
2005
Measurements of beta decay reduced transition probabilities are particularly relevant in nuclei far from the stability line. It has been demonstrated that a proper measurement of this quantity requires the use of the total absorption technique, which has become a reliable tool in recent years, thanks to the increased efficiency of the associated spectrometers and the development of new analysis techniques. In this paper, we present a brief history of the past and present use of these detectors and how they might be developed in the future.