Search results for "Chemical separation"
showing 10 items of 15 documents
Direct identification of 103–107Mo by a rapid chemical separation procedure
1977
Abstract The nuclides 103–107Mo have been identified by means of γ-ray spectroscopy after the separation of molybdenum from fission products of 235U and 239Pu by a rapid chemical procedure. Half-lives of 67.5 ± 1.5 s for 103Mo, 59.4 ± 0.8 s for 104Mo, 36.7 ± 1.0 s for 105Mo, 8.4 ± 0.5 s for 106Mo and 3.5 ± 0.5 s for 107Mo have been determined and the main γ-lines were assigned to the decay of these isotopes. Some evidence for 108Mo with a half-life ≤2 s has also been obtained.
Decay properties of neutron-rich niobium isotopes
1976
The decay of neutron-rich niobium isotopes in the mass region $A\ensuremath{\simeq}100$ has been investigated by $\ensuremath{\gamma}$-ray singles and $\ensuremath{\gamma}$-$\ensuremath{\gamma}$ coincidence measurements. The isotopes were produced by thermal-neutron induced fission of $^{235}\mathrm{U}$, $^{239}\mathrm{Pu}$, and $^{249}\mathrm{Cf}$, and niobium was separated from fission-product mixtures with an automated chemical procedure. Isomerism was found in the even-mass niobium isotopes with the following half-lives: 1.5 and 3.1 sec for $^{100}\mathrm{Nb}$, 1.3 and 4.3 sec for $^{102}\mathrm{Nb}$, and 0.8 and 4.8 sec for $^{104}\mathrm{Nb}$. Half-lives and $\ensuremath{\gamma}$ rays…
An EC-branch in the decay of 27-s 263Db: Evidence for the isotope 263Rf
2003
Summary 27-s 263Db was produced in the 249Bk ( 18O, 4n) reaction at 93 MeV. The activity was transported by a He/KCl-jet to the laboratory where it was collected for 15 min and then subjected to a chemical separation specific for group-4 elements. The activity was dissolved in 0.5 M unbuffered α-HiB and eluted from a cation-exchange column. The effluent was made 9 M in HCl and group-4 tetrachlorides were extracted into TBP/Cyclohexane which was evaporated to dryness on a Ta disc. The Ta discs were assayed for α and SF activity. A SF activity with a half life on the order of 20 min was observed and assigned to the nuclide 263Rf. It is formed by electron-capture decay of 263Db with a decay br…
A system for rapid radiochemical separations from aqueous solutions
1969
Abstract For the study of short-lived fission products, an automatic system has been developed that allows to irradiate aqueous solutions sealed in polystyrene capsules, to separate chemically the radioactive products formed, and to start counting, all within a few seconds. Irradiations are performed in a pneumatic tube system installed in a horizontal beam hole of a reactor. The capsule is projected into a separation apparatus where it breaks by impact. Its content is then sucked through a thin reactive layer that takes up the desired product. The whole sequence of irradiation, transportation, chemical separation, and counting is controlled by automatic timers. The adaption of this techniq…
Extraction of lanthanides and actinides by a magnetically assisted chemical separation technique based on CMPO-calix[4]arenes
2001
A novel particulate system carrying CMPO ligands pre-organised on a calixarene scaffold has been synthesised and demonstrated to extract Eu3+, Am3+ and Ce3+ at high efficiency from simulated nuclear waste streams.
Application of fast solvent extraction processes to studies of exotic nuclides
1998
Fast solvent extraction is a chemical separation method, which can be applied to study exotic nuclides. Since about 1970 the SISAK technique, which is an on-line method based on multi-stage solvent extraction separations, has been successfully used to investigate the nuclear properties of β-decaying nuclides with half-lives down to about one second. During the last decade it has become possible to produce transactinide elements in high enough yields to investigate their chemical properties on a one-atom-at-a-time scale. For this purpose it was necessary to improve and change the detection part of the SISAK system in order to be capable to detect spontaneously fissioning and α-decaying nucli…
Determination of gunshot residues by neutron activation analysis
1973
Systematic investigations of gunshot residues, deposited around the bullet hole, have been carried out. The traces were produced by firing on filter papers from distances of 5 to 200 cm using one rifle and three pistols as arms. Antimony, lead and barium were quantitatively determined after irradiating the samples in the nuclear reactor TRIGA Mainz by measurement of gamma-lines of122mSb,122Sb,207mPo and139Ba. The determinations were made purely instrumentally and-where the half lives were long enough-also after chemical separation of the nuclides. The amount of the elements were determined in dependence of the firing distance and of the area around the bullet hole.
Chemical properties of rutherfordium (Rf) and dubnium (Db) in the aqueous phase
2016
Recent experimental studies of the chemical characterization of the first two transactinide elements, rutherfordium (Rf) and dubnium (Db), conducted atom-at-a-time in aqueous phases are reviewed. A short description on experimental techniques based on partition methods, specifically automated rapid chemical separation systems, is also given. Perspectives for aqueous-phase chemistry experiments on heavier elements are briefly discussed.
Hexafluoro complex of rutherfordium in mixed HF/HNO3 solutions
2008
Formation of anionic fluoride-complexes of element 104, rutherfordium, produced in the 248 Cm( 18 O, 5n) 261 Rf reaction was studied by anion-exchange on an atom-at-a-time scale. It was found that the hexafluoro complex of Rf, [RfF 6 ] 2- , was formed in the studied fluoride ion concentrations of 0.0005-0.013 M. Formation of [RfF 6 ] 2- was significantly different from that of the homologues Zr and Hf, [ZrF 6 ] 2- and [HfF 6 ] 2- ; the evaluated formation constant of [RfF 6 ] 2- is at least one-order of magnitude smaller than those of [ZrF 6 ] 2- and [HfF 6 ] 2- .
Studies of short-lived fission products by means of the multistage solvent extraction system SISAK
1990
The multistage solvent extraction system SISAK is described. The system is used for online studies of nuclides with half-lives down to ∼1 s. Some of the chemical separation procedures are presented, and a survey is given on the results obtained so far. The possiblity to gain access to nuclides with even shorter half-lives is also discussed.