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ISOLDE-collaboration
... Similar observations have also been made by Ganguly et. al. [21] during Rietveld fitting of the XRD pattern of their ZnO nano particles synthesized by chemical route, which they have attributed to be due to irregular structures of the nanocrystals or variation in crystallite size. However, the overall fit for the as-deposited samples presented here are reasonably good with low χ 2 values. ...
Pure, Co doped and (Co, Cu) co-doped ZnO nanocrystals have been prepared by wet chemical route at room temperature to investigate the effect of Cu doping in Co doped ZnO nanocrystals. The nanocrystals have initially been characterized by X-ray diffraction, FTIR, Raman, optical absorption and EPR spectroscopy and the results were corroborated with DFT based electronic structure calculations. Magnetic properties of the samples have been investigated by studying their magnetic hysteresis behavior and temperature dependence of susceptibilities. Finally the local structure at the host and dopant sites of the nanocrystals have been investigated by Zn, Co and Cu K edges EXAFS measurements with synchrotron radiation to explain their experimentally observed magnetic properties.
... A key aspect for most experiments performed at REX is the beam purity. The Resonant Ionisation Laser Ion Source [5] and the molecular sideband technique [6] are now widely used at REX. In the last year a number of new techniques have been tested to remove contaminants from the beam. ...
The ISOLDE charge breeder and post-accelerator REX has been operational for more than 5 years and is now routinely delivering beams to nuclear physics experiments. An overview of the present performances of the machine and a number of recent developments and tests of beam purification techniques are presented in this paper.
... However, because of the low melting temperature of titanium (1668 @BULLET C) and a local overheating during impact of the intense proton beam pulses (up to 3.4 × 10 13 protons in a 2.4 µs beam pulse), the titanium foil targets showed rapid sintering, causing strongly hampered release character- istics. As an alternative to pure elements, carbides or oxides are often used as compounds with relatively high temperature stability [6] . Different oxides showed good release characteristics for noble gases [3]. ...
The reaction has been studied for the first time. A sample containing atoms was produced at the ISOLDE facility at CERN. The number of atoms in the layer was determined by measuring the -activity using a primary standardisation method. Subsequently, the sample was irradiated with thermal neutrons at the High Flux Reactor of the Institut Laue–Langevin. An upper limit of was obtained for the reaction cross-section.
... A selection of the data obtained is presented in this paper, with emphasis on the γ-spectroscopy data. The release of the volatile elements from an ISOL target is a complex process [9, 10]. The volatile species formed after the spallation reaction diffuse first in the liquid. ...
The IS419 experiment at the ISOLDE facility at CERN dedicated to the measurement of production and release rates of volatile elements from an irradiated Pb/Bi target by a proton beam of 1/1.4 GeV has been completed. The release of He, Ne, Ar, Br, Kr, Cd, I, Xe, Hg, Po and At isotopes was investigated at different target temperatures, ranging from 250 °C to 600 ° C. Three experimental methods were used for the mass-separated, ionized beams: i) implantation of short- and medium-lived isotopes in a tape and on-line detection with a HPGe γ detector; ii) implantation of longer-lived isotopes in Al foils and off-line detection with a HPGe detector; iii) a Faraday Cup used mainly for stable nuclides. The results were compared with predictions from the FLUKA and MCNPX codes using different options for the intra-nuclear cascades and evaporation/fission models. Results show good agreement with calculations for Hg and for noble gases. For other elements such as iodine it is apparent that only a fraction of the produced isotopes is released. The results from FLUKA and MCNPX with the INCL4/ABLA models are in general more satisfactory than those obtained using MCNPX with the standard Bertini/Dresner model combination. Interestingly also significant yields of 204-210At isotopes were observed. At isotopes are produced either by (p, π-xn) charge exchange reactions on 209Bi or by secondary reactions involving 3He and 4He. Despite the non-release of polonium from Pb/Bi targets at typical operation temperatures, a smaller amount of highly radiotoxic Po isotopes can actually be liberated indirectly as decay daughters of the released astatine.
... Practically every atom entering the plasma volume can get ionized regardless its chemical nature. Elemental selectivity can be achieved by thermodynamical (cold transfer line) or chemical (separation of molecules) "tricks" [1]. The first method is of advantage for low-melting elements with high vapor pressure (noble gases, Cd, Hg), the latter for reactive non-metals (C, N, O, Se, etc.) and metals which tend to form stable molecules (e.g. ...
The three main requirements to the ion source of an ISOL facility are efficiency, selectivity and rapidity. For many metallic elements these requirements are ideally fulfilled by a resonance ionization laser ion source (RILIS). Presently such ion sources are used at the RIB facilities IRIS (Gatchina), ISOLDE (CERN), LISOL (Leuven), TIARA (Takasaki) and IMP (Lanzhou) to provide beams with low isobaric contamination. The isotopically pure beams enabled to make spectacular progress, for instance in nuclear spectroscopy of very rare isotopes. The scanning of the hyperfine structure with a small bandwidth laser allows moreover to separate individual isomers. The RILIS has also been used as a sensitive tool for atomic spectroscopy (measurement of the isotope shift and of nuclear moments) of exotic isotopes.
Many elements are rapidly released from oxide matrices. Some oxide powder targets show a fast sintering, thus losing their favorable release characteristics. Loosely packed oxyde fiber targets are less critical since they may maintain their open structure even when starting to fuse together at some contact points. The experience with various oxyde fiber targets (titania, zirconia, ceria and thoria) used in the last years at ISOLDE is reviewed. For short-lived isotopes of Cu, Ga and Xe the zirconia and ceria targets respectively provided significantly higher yields than any other target (metal foils, oxide powders, etc.) tested before. Titania fibers, which were not commercially available, were produced in a relic process by impregnation of a rayon felt in a titanium chloride solution and subsequent calcination by heating the dried felt in air. Thoria fibers were obtained either by the same process or by burning commercial gas lantern mantle cloth. In the future a beryllia fiber target could be used to produce very intense ^6He beams (order of 10^13 ions per s) via the ^9Be(n, alpha) reaction using spallation neutrons.
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