No abstract available

[en] Multiwall carbon nanotubes (MWCNTs) were modified by nitric acid solution and then used to study the adsorption of cesium from aqueous solution using a batch technique under ambient conditions. As produced and oxidized MWCNTs were characterized by nitrogen adsorption/desorption, Boehm's titration method and Fourier transform infrared spectroscopy. The physical properties of MWCNTs such as functional groups, total number of acid sites and specific surface area were greatly improved after oxidation, and these were responsible for more sorption of cesium from aqueous solution and made them more dispersible in water. The adsorption of cesium ions as a function of contact time, initial concentration of cesium, pH, ionic strength and oxidized MWCNT concentrations was also investigated. The results showed that cesium adsorption percentage strongly depended on the pH value, oxidized MWCNT content and on the solution ionic strength. Kinetic data indicated that the adsorption process achieved equilibrium within 80 min. Equilibrium data for as produced and oxidized MWCNTs was well described by both Freundlich and Langmuir isotherms. The dominant mechanism of cesium adsorption on oxidized MWCNTs may be mainly attributed to ion exchange. This study suggests that oxidized MWCNTs can be a promising candidate for the removal of cesium from nuclear waste solution. (author)

No abstract available

[en] A quantitative interpretation of the molecular satellites of the 6²S-7²P doublet of cesium is given. The calculus, based on the existence of the long-range interaction forces, with approximately R^-3 potential, leads to three molecular states resulting from (7²P-6²S) interaction and two molecular states resulting from (7²P-6²S) interaction, to which electronic transitions from the ground state of the polarization molecule are possible. The potential energy curve was calculated for each molecular state over the whole range of the distance. The theory places the origin of the molecular satellites in the vibrational transitions which take place from the vibrational levels of one ground state to the vibrational levels of more excited molecular states, belonging to the same (7²P-6²S) interaction. (author)

[en] The one-atom detection technique has been used to search for atoms which are created from the neutralization of heavy ions as they lose their energy in a gas. When Cf-252 decays by binary fission, Cs sup(n+) ions are formed approximately 14% of the time (in the heavy mass peak). Thus, these ions were injected into a gas at a low rate such that the Cs neutral atom could be searched for individually and at a known time after its production. A delay of a few microseconds allowed time for collection of the 3 x 10⁶ electrons created by the 80-MeV Cs sup(n+) energy; then a pulsed laser was fired along each particle track to remove one electron from each Cs atom by the saturated two-step resonance ionization process. These electrons were then drifted into a gas proportional counter and detected individually to measure the probability that a neutral Cs atom would be found at the end of the fission particle track. Our results show that a Cs neutral species is formed about 14% of the time, and thus nearly all Cs sup(n+) ions become Cs⁰ when the ions are thermalized in P-10 (90% Ar plus 10% CH₄) counting gas. Extensions of the technique to obtain other details of particle track structure will be discussed. For example, it is possible to detect even one negative ion created in a track where nearly 100 MeV of energy is absorbed; ant it is likewise possible to determine the population of quantum selected excited states left in the wake of these tracks

[en] The multiple beam induction linac experiment (MBE-4) was built to study the accelerator physics of the low energy, electrostatically focussed end of a driver for heavy ion inertial confinement fusion. In this machine four beams of Cs⁺ ions are accelerated through 24 common induction gaps while being focussed in separate AG focussing channels. Each channel consists of a syncopated FODO lattice of 30 periods. We report results of the most recent studies of the transverse beam dynamics of a single drifting (180 keV) beam in this machine. The dependence of the emittance on the zero-current phase advance shows systematic variations which may be understood in the light of previous theoretical work on this topic. This result, unique to the beam parameters of a linac for heavy ion fusion, will be discussed in the context of its implications for a driver design. In addition we will discuss recent measurements of the motion of the beam centroid through the linac. These measurements, coupled with simulations, have proven to be a powerful tool in determining the presence of misalignment errors in the lattice of the accelerator. 6 refs., 3 figs

[en] Highlights: • A dense ceramic wasteform is prepared by hot isostatic pressing Cs-exchanged IONSIV^®. • Cs was encapsulated in two phases, Cs₂TiNb₆O₁₈ and Cs₂ZrSi₆O₁₅, in the HIPed Cs-IONSIV^®. • HIPed Cs-IONSIV^® samples have low aqueous leach rates of Cs ions that are very comparable with those reported for hollandite.

[en] A 'bimodal' or upper- and lower-rim functionalized 'calix-crown-5' reported herein was unexpectedly formed preferentially in a cone conformation. This was confirmed both by NMR spectroscopy and by single-crystal X-ray crystallography. The thioacetate functionalities on the new calix-crown-5 enabled it to form stable SAMs on the Au surface of a micro-cantilever, and a sensitive cesium ion sensor. (authors)

[en] Two processes will be discussed, which could contribute to a theoretical understanding of the formation of negative ions in cesium driven ion sources. A comparison of a model calculation with existing experimental data on negative ion currents is being presented. It turns out that for some metallic elements like Au and Pt the dominant mechanism may be characterized by a charge-exchange of sputtered atoms in a condensed Cs-layer on the target surface. A different process is required to explain yields of carbon, silicon and the negative ions of the other IV-group elements. A formula without adjustable parameters is derived on the basis of the two processes to calculate negative ion currents from the sputtering source. This formula gives reasonable agreement with measured data. (orig.)

[en] The negative cluster ion mass distribution under cesium impact of graphite and amorphous carbon samples was studied using a cesium sputter negative ion source. In the case of graphite sputtering, the regular odd-even oscillations with the even clusters being higher in intensity than the odd ones for C_n^- up to n = 9 and a reversal in this trend for n > 13 as observed by several others was confirmed. On the other hand, in the case of amorphous carbon sputtering, the intensity distribution pattern was seen to be similar to that of graphite up to n = 9, but the trend of even clusters having higher intensity continued up to n 17, beyond which the pattern was similar to that of graphite. In the case of amorphous carbon sputtering, the intensity drop from C₂ to C₁₈ can be represented by a power law with a single exponent, whereas in the case of graphite sputtering, two different exponents are required to explain the slower fall from C₂ to C₈ followed by a steeper drop from C₉ to C₁₈. Further, the intensity distribution of the CsC_n^- clusters was also found to be different in the two cases. (author)