Search results for "CLEAR"
showing 10 items of 27042 documents
A modular neutron irradiator based on 241Am-Be neutron sources
2010
Neutron irradiator facilities with 241Am-Be sources are worldwide used in order to perform neutron activation analysis (NAA), to investigate materials in different research areas or to test and calibrate neutron detectors and environmental or personal dosemeters. The use of a neutron irradiator is advantageous because of its very stable neutron flux, even it is many orders of magnitude lower than the one of a nuclear reactor or a particle accelerator. Most of irradiators are realized with neutron sources located at fixed positions and accordingly the characteristics of neutron spectrum previously assessed do not change. Therefore, an interesting choice is to have a modular facility, capable…
Friction and Heat Transfer in Membrane Distillation Channels: An Experimental Study on Conventional and Novel Spacers
2022
The results of an experimental investigation on pressure drop and heat transfer in spacer-filled plane channels, which are representative of Membrane Distillation units, are presented and discussed. Local and mean heat transfer coefficients were obtained by using Thermochromic Liquid Crystals and Digital Image Processing. The performances of a novel spacer geometry, consisting of spheres that are connected by cylindrical rods, and are hereafter named spheres spacers, were compared with those of more conventional woven and overlapped spacers at equal values of the Reynolds number Re (in the range ~150 to ~2500), the pitch-to-channel height ratio, the flow attack angle and the thermal boundar…
In-gas laser ionization and spectroscopy of actinium isotopes near the N=126 closed shell
2017
The in-gas laser ionization and spectroscopy (IGLIS) techniquewas applied on the $^{212–215}$Ac isotopes, produced at the Leuven Isotope Separator On-Line (LISOL) facility by using the in-gas-cell and the in-gas-jet methods. The first application under on-line conditions of the in-gas-jet laser spectroscopy method showed a superior performance in terms of selectivity, spectral resolution, and efficiency in comparison with the in-gas-cell method. Following the analysis of both experiments, the magnetic-dipole moments for the $^{212–215}$Ac isotopes, electric-quadrupole moments and nuclear spins for the $^{214,215}$Ac isotopes are presented and discussed. A good agreement is obtained with lar…
Two new organic-selenate salts: syntheses and crystal structures of bis(di-iso-propylammonium) selenate and di-n-butylammonium hydrogenoselenate
2017
Abstract Two new dialkyammonium selenate salts [i-Pr2NH2]2[SeO4] (1) and [n-Bu2NH2][HSeO4] (2) have been isolated and characterized by single-crystal X-ray diffraction. Salt 1 crystallizes in the monoclinic system, space group P21/n with a=8.7190(5), b=8.8500(4), c=22.5953(9) Å, β=94.6290(17)°, V=1737.84(14) Å3 and Z=4. Salt 2 crystallizes in the monoclinic system space group P21/n with a=10.9328(9), b=8.1700(6), c=13.8095(11) Å, β=97.130(3)°, V=1223.94(17) Å3 and Z=4. In both salts, dialkylammonium cations and selenate anions are connected through NH···O and OH···O hydrogen bonds. In the crystal structure, 1 and 2 are organized in layer-like arrangements. Structural characterizations were …
Gallium preference for the occupation of tetrahedral sites in Lu3(Al5-xGax)O12multicomponent garnet scintillators according to solid-state nuclear ma…
2019
Abstract In this study, the distributions of aluminum and gallium atoms over the tetrahedral and octahedral sites in the garnet structure were investigated in mixed Lu3Al5-xGaxO12 crystals by using 27Al and 71Ga magic angle spinning nuclear magnetic resonance (NMR) and single crystal 71Ga NMR. The experimental study was supported by theoretical calculations based on density functional theory (DFT) in order to predict the trends in terms of the substitutions of Al by Ga in the mixed garnets. Both the experimental and theoretical results indicated the non-uniform distribution of Al and Ga over the tetrahedral and octahedral sites in the garnet structure, with a strong preference for Ga occupy…
Charge radius changes of even-even neutron-rich Tellurium isotopes
2005
Laser spectroscopy based on resonant ionization of laser-desorbed atoms has been used to study the neutron-rich tellurium isotopes with the COMPLIS facility at ISOLDE-CERN. The isotope shift and the hyperfine structure of several neutron-rich Te isotopes: $^{120–136}$Te and $^{123m–133m}$Te have been measured. From the hyperfine structure and the isotope shift we can extract the magnetic and quadrupole moments and the change in the mean square charge radius respectively. The mean square charge radii of the even-even isotopes have been deduced and their comparison with the known data for the other elements near Z=50 is presented. The experimental $\delta$ is compared with that obtained from …
Characterization of Supersonic Gas Jets for High-Resolution Laser Ionization Spectroscopy of Heavy Elements
2018
© 2018 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the »https://creativecommons.org/licenses/by/4.0/» Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. The method of laser spectroscopy in supersonic gas jets was proposed for high-resolution and high-efficiency in-gas laser ionization and spectroscopy studies of short-lived nuclei. The flow properties of such supersonic gas jets have been characterized under off-line conditions. Planar laser-induced fluorescence spectroscopy of s…
A concept for the extraction of the most refractory elements at CERN-ISOLDE as carbonyl complex ions
2021
The European physical journal / A 58(5), 94 (2022). doi:10.1140/epja/s10050-022-00739-1
Characterization of a CZT focal plane small prototype for hard X-ray telescope
2005
The promise of good energy and spatial resolution coupled with high efficiency and room temperature operation has fuelled a large international effort to develop cadmium zinc telluride (CZT) for hard X-ray applications. We are involved on the development of a hard X-ray telescope based on multilayer optics and focal plane detector operative in the 10-80 keV energy range. This telescope requires a high efficiency focal plane providing both fine spatial resolution and spectroscopy with a compact and robust design. This paper reports preliminary results on the characterization both in spectroscopic and spatial response of two small pixellated CZT detectors (10times10times1 mm3 and 10times10tim…
First trap-assisted decay spectroscopy of the $$^{81}$$Ge ground state
2022
AbstractThe $$\beta $$ β -delayed $$\gamma $$ γ spectroscopy of $$^{81}$$ 81 As has been performed using a purified beam of $$^{81}$$ 81 Ge $$(9/2^+)$$ ( 9 / 2 + ) ground state at the Ion Guide Isotope Separator On-Line facility (IGISOL). The $$^{81}$$ 81 Ge$$^+$$ + ions were produced using proton-induced fission of $$^{232}$$ 232 Th and selected with the double Penning trap JYFLTRAP for the post-trap decay spectroscopy measurements. The low-spin $$(1/2^+)$$ ( 1 / 2 + ) isomeric-state ions $$^{81m}\hbox {Ge}^+$$ 81 m Ge + were not observed in the fission products. The intrinsic half-life of the $$^{81}$$ 81 Ge ground state has been determined as $$T_{1/2}=6.4(2)~\hbox {s}$$ T 1 / 2 = 6.4 ( …