Search results for "Recoil"
showing 10 items of 309 documents
Towards saturation of the electron-capture delayed fission probability: The new isotopes $^{240}Es$ and $^{236}Bk$
2016
Abstract The new neutron-deficient nuclei 240 Es and 236 Bk were synthesised at the gas-filled recoil separator RITU. They were identified by their radioactive decay chains starting from 240 Es produced in the fusion–evaporation reaction 209 Bi( 34 S,3n) 240 Es. Half-lives of 6 ( 2 ) s and 22 − 6 + 13 s were obtained for 240 Es and 236 Bk, respectively. Two groups of α particles with energies E α = 8.19 ( 3 ) MeV and 8.09 ( 3 ) MeV were unambiguously assigned to 240 Es. Electron-capture delayed fission branches with probabilities of 0.16 ( 6 ) and 0.04 ( 2 ) were measured for 240 Es and 236 Bk, respectively. These new data show a continuation of the exponential increase of ECDF probabilitie…
Al2O3 ALD films grown using TMA + rare isotope 2H216O and 1H218O precursors
2021
Abstract In this work hydrogen and oxygen migration and exchange reactions in the atomic layer deposited (ALD) Al2O3 thin films were studied together with hydrogen incorporation by varying deposition parameters. Al2O3 films deposited at low temperatures can contain more than 20 at.% of hydrogen. Both higher temperature and longer purge length decrease the hydrogen and carbon concentrations significantly. In order to track the hydrogen and oxygen movement in the films, heavy water (2 H 2 16 O) and oxygen-18 enriched water (1 H 2 18 O) were used as precursors in combination with trimethylaluminium (TMA). Different isotopes of the same element were quantified by means of time-of-flight elastic…
Transition probability studies in175Au
2013
Transition probabilities have been measured between the low-lying yrast states in 175Au by employing the recoil distance Doppler-shift method combined with the selective recoil-decay tagging technique. Reduced transition probabilities and magnitudes of transition quadrupole moments have been extracted from measured lifetimes allowing dramatic changes in nuclear structure within a low excitation-energy range to probed. The transition quadrupole moment data are discussed in terms of available systematics as a function of atomic number and aligned angular momentum.
Spectroscopic Tools Applied to Flerovium Decay Chains
2020
Abstract An upgraded TASISpec setup, with the addition of a veto DSSD and the new Compex detector-germanium array, has been employed with the gas-filled recoil separator TASCA at the GSI Helmholtzzentrum für Schwerionenforschung Darmstadt, to study flerovium (element 114) decay chains. The detector upgrades along with development of new analytical techniques have improved the sensitivity of the TASISpec setup for measuring α-photon coincidences. These improvements have been assessed with test reactions. The reaction 48Ca+206,207Pb was used for verification of experimental parameters such as transmission to implantation DSSD and target-segment to α-decay correlations. The reaction 48Ca+ nat …
Hydrogen influence on the structure and properties of amorphous hydrogenated carbon films deposited by direct ion beam
2008
Abstract The present work provides results for amorphous hydrogenated carbon (a-C:H) films grown by direct ion beam deposition method. Acetylene and its mixtures with hydrogen were used. The films were characterized by Rutherford backscattering spectrometry, elastic recoil detection, Raman spectroscopy, ellipsometry, infrared spectroscopy, and microhardness measurements. These techniques indicated that an admixture of hydrogen yields a lower deposition rate, a higher content of total and bounded hydrogen in the a-C:H films, and a lower film density. The optical and mechanical properties depend on both, hydrogen concentrations in the gas phase and in the films, and show a strong diamond-like…
Rapid continous radiochemical separations by thermochromatography in connection with a gas-jet recoil-transport system
1980
Abstract A combination of a gas-jet recoil-transport system with a thermochromatographic system has been studied as a technique for rapid, continuous radiochemical separations. Fission products were used as a model for complex mixtures of elements. A nitrogen gas-jet containing potassium chloride clusters was applied to transport nuclides produced in a reactor from the target area to the thermochromatographic column. Conversion of the reaction products carried by the gas-jet volatile species was achieved by stopping the clusters in a quartz-wool plug located in the column and kept at high temperatures and feeding a reactive gas into the column. Several reactive gases producing volatile chlo…
Chemical reactions in a gas-jet recoil-transport system: Continuous separation procedure for selenium and tellurium from fission products
1978
Abstract Chemical selectivity in a gas-jet recoil-transport system can be achieved by chemical reactions with the carrier gas. This is demonstrated for an ethylene-nitrogen jet in which volatile species of selenium and tellurium are formed by passing the gas through a reaction zone heated to 860°C. Rapid continuous separation procedures for selenium and tellurium from fission products based on this effect are described and some decay data of the neutron-rich nuclides 85–88Se and 135–137Te obtained with these methods are given.
Comparison of myocardial perfusion reserve before and after coronary balloon predilatation and after stent implantation in patients with postangiopla…
1996
Background Stents provide a scaffold for coronary arteries after angioplasty and inhibit elastic recoil. Methods and Results In 25 patients with postangioplasty restenosis of the left anterior descending artery, ECG-gated digital subtraction coronary angiograms were recorded at baseline and during hyperemia (12 mg papaverine IC) before and after balloon predilatation (PTCA), after implantation of a Palmaz-Schatz stent, and after 6 months. Densitometric evaluation revealed different time and density parameters to calculate two definitions of myocardial perfusion reserve (MPR1 and MPR2) and maximum flow ratio (MaxFR). Poststenotic MPR1 increased from 1.57±0.14 to 2.59±0.86 after PTCA and to …
Transport of recoil atoms in a stream of liquid-air-cooled pure helium
1974
Abstract Pure commercial helium cooled down to the temperature of liquid air (80 K) has been used for rapid transportation of recoil atoms over distances as long as 10 m. Transport efficiencies of several tens of per cent have been obtained for recoil atoms resulting from alpha decay or from decay by fission. The angle of divergence of the beam of recoil atoms at the exit of the transport capillary is measured to be (11±2)° for particles of mass number A = 211. Experimental results are discussed in terms of thermal diffusion. The elimination of carrier vapors will probably simplify the use of the helium-jet technique in on-line mass separators.
Influence of plasma chemistry on impurity incorporation in AlN prepared by plasma enhanced atomic layer deposition
2013
Impurities in aluminum nitride films prepared by plasma enhanced atomic layer deposition using NH3-, N2/H2- and N2-based plasmas are investigated by combining time-of-flight elastic recoil detection analysis (ERDA) and Fourier transform infrared spectroscopy. Different atomistic growth mechanisms are found to exist between the plasma chemistries. N2-plasma is shown as not suitable for the low-temperature deposition of AlN. Films deposited by NH3- and N2/H2-based processes are nitrogen rich and heavily hydrogenated. Carbon impurities exist at higher concentrations for the N2/H2-processes. The discovery of nitrile groups in the films indicates that carbon impurities can be partially attribute…