Search results for "element"
showing 10 items of 13601 documents
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…
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…
Towards controlling PCDD/F production in a multi-fuel fired BFB boiler using two sulfur addition strategies
2014
Abstract PCDD/F abatement strategies – sulfur pellet addition and peat co-combustion – were tested for a BFB boiler facility utilizing SRF-bark-sludge as fuel. In this paper chemical and physical analyses of electrostatic precipitator (ESP) fly ashes were used to explain the differences in the performance of these strategies. These analyses revealed a difference between the coarse and fine fly ashes collected in the ESP. Chemical analysis of the fine fly ashes revealed high concentration of easily volatilized elements while the SEM micrographs showed that fine ash are composed of clusters of spherical particles, thereby leading to a conclusion that fine ashes were originally in a gas phase …
Electron spectra in forbidden β decays and the quenching of the weak axial-vector coupling constant gA
2017
Evolution of the electron spectra with the effective value of the weak axial-vector coupling constant gA was followed for 26 first-, second-, third-, fourth- and fifth-forbidden β− decays of odd-A nuclei by calculating the involved nuclear matrix elements (NMEs) in the framework of the microscopic quasiparticle-phonon model (MQPM). The next-to-leading-order terms were included in the β-decay shape factor of the electron spectra. The spectrum shapes of third- and fourth-forbidden nonunique decays were found to depend strongly on the value of gA, while first- and second-forbidden decays were mostly unaffected by the tuning of gA. The gA-driven evolution of the normalized β spectra was found t…
Total absorption γ -ray spectroscopy of niobium isomers
2019
15 pags. 17 figs., 5 tabs.
Tin resonance-ionization schemes for atomic- And nuclear-structure studies
2020
This paper presents high-precision spectroscopic measurements of atomic tin using five different resonance-ionization schemes performed with the collinear resonance-ionization spectroscopy technique. Isotope shifts were measured for the stable tin isotopes from the $5{s}^{2}5{p}^{2}\phantom{\rule{0.28em}{0ex}}^{3}{P}_{0,1,2}$ and ${}^{1}{S}_{0}$ to the $5{s}^{2}5p6s\phantom{\rule{0.28em}{0ex}}^{1}{P}_{1},^{3}{P}_{1,2}$ and $5{s}^{2}5p7s{\phantom{\rule{0.28em}{0ex}}}^{1}{P}_{1}$ atomic levels. The magnetic dipole hyperfine constants ${A}_{\mathrm{hf}}$ have been extracted for six atomic levels with electron angular momentum $Jg0$ from the hyperfine structures of nuclear spin $I=1/2$ tin isot…
Spectroscopy of short-lived radioactive molecules
2020
Molecular spectroscopy offers opportunities for the exploration of the fundamental laws of nature and the search for new particle physics beyond the standard model1–4. Radioactive molecules—in which one or more of the atoms possesses a radioactive nucleus—can contain heavy and deformed nuclei, offering high sensitivity for investigating parity- and time-reversal-violation effects5,6. Radium monofluoride, RaF, is of particular interest because it is predicted to have an electronic structure appropriate for laser cooling6, thus paving the way for its use in high-precision spectroscopic studies. Furthermore, the effects of symmetry-violating nuclear moments are strongly enhanced5,7–9 in molecu…
Acetic acid leaching of neodymium magnets and iron separation by simple oxidative precipitation
2022
Neodymium-iron-boron (NdFeB) has become the most prominent permanent magnet alloy, with a wide variety of applications and an ever-increasing demand. Their recycling is important for securing the supply of critical raw materials used in their manufacturing. The use of organic acids such as acetic acid has been of recent interest for the recycling of waste NdFeB magnets. Despite achieving good leaching efficiencies, the published literature has not properly investigated the effects of key factors influencing the acetic acid leaching process and their respective interactions, which has lead to conflicting findings as to what conditions are optimal. The present work goes to show that no such o…
Atgriezeniskās saites startēģijas mācīšanās kultūras veicināšana pamatskolā
2019
Viena no neatņemamajām sastāvdaļām mācību procesā ir pastāvīgi saņemt atgriezenisko saiti. Izmantojot iegūto informāciju, atgriezeniskā saite palīdz skolēniem labāk saprast, cik lielā mērā mūsu pašu priekšstati par sevi, vai paveikto sakrīt ar citu iesaistīto cilvēku redzējumu, un, kas darāms tālāk. Atgriezeniskā saite palīdz pilnveidoties pamatīgāk iedziļinoties, kā arī labāk aptvert likumsakarības, turklāt, tas atspoguļo skolēnu mācīšanās kultūru, viņu attieksmi pret mācību procesu. Diplomdarba mērķis ir pētīt un apzināties atgriezeniskās saites stratēģiju nozīmi, uzlabojot mācīšanās procesu darbā ar skolēniem pamatskolā.Pētījums tika veikts Rīgas Valda Zālīša pamatskolā, kurā piedalījās …
Spēles elementu izmantošana vārdu krājuma un gramatisko formu apgūšanai krievu valodas kā svešvalodas stundās 4. klasē
2022
Latvijas Izglītības un zinātnes ministrijas apstiprinātajā izglītības programmā, 4.klašu skolēniem tiek piedāvāta otrās svešvalodas apguves izvēle. Skolēni, kuri izvēlas apgūt krievu valodu, bieži vien saskaras ar dažādām grūtībām vārdu krājuma un gramatikas formu apgūšanā, kas saistītas ar alfabēta atšķirībām, izrunas, frāžu un teikumu uzbūves specifiku. Dotajā diplomdarbā, pamatojoties uz teorētisko materiālu un tā praktisko pielietojumu, ir apskatītas spēles elementu izmantošanas iespējas vārdu krājuma un gramatikas formu apgūšanai krievu valodas kā svešvalodas stundās 4.klasē. Saskaņā ar veiktā pētījuma rezultātiem, kurā piedalījās 27 skolēni, tika noteikti spēļu veidi, kurus var ieteik…