The K<Superscript>-</Superscript>α scattering length and the reaction dd↦αK<Superscript>+</Superscript>K<Superscript>-</Superscript>

We present predictions for the K^-α scattering length obtained within the framework of the multiple-scattering approach. Evaluating the pole position of the K^-α scattering amplitude within the zero-range approximation, we find a loosely bound K^-α state with a binding energy of E_R = - 2,..., - 7 MeV and a width Γ_R = 11,..., 18 MeV. We propose to measure the K^-α scattering length through the final-state interaction between the α and K^--meson produced in the reaction dd↦αK⁺K^-. It is found that the K^-α invariant-mass distribution from this reaction at energies near the threshold provides a new tool to determine the s-wave K^-α scattering length.     

Isotopomer selective optimization of <Superscript>39</Superscript>K<Superscript>85</Superscript>Rb<Superscript>+</Superscript> and <Superscript>41</Superscript>K<Superscript>87</Superscript>Rb<Superscript>+</Superscript> using optimal control

We report on isotope selective three-photon ionization of two isotopomers of KRb by applying evolution strategies. The particularity of this experiment is based on the high resolution phase and amplitude modulation of the fs-laser pulses provided by a 2 × 640 pixel pulse shaper. The optimization in a closed feedback loop performed with spectrally broad pulses centered at 840 nm shows high enhancements of one isotopomer at the expense of the other isotopomer and vice versa. From the optimal laser field we aim to gain details about the selective ionization sequence and the wavepacket evolution on the involved vibrational states.     

Theoretical analysis of <Superscript>6</Superscript>He + <Superscript>12</Superscript>C scattering by means of the model of microscopic optical potential

The ⁶He + ¹²C elastic scattering at E = 3.0, 38.3, and 41.6 MeV/nucleon is analyzed using the microscopic model of optical potential. According to this approach, two or three parameters are fitted that renormalize the depth of real, imaginary, and surface parts of the calculated optical potential. In this case, the ambiguity of the obtained sets of fitting parameters remains, but can be reduced by introducing an additional criterion of selection: the dependence of the volume integrals of the optical potential on the energy. The structure of the obtained optical potential, the role of the nuclear medium, the formation of the imaginary part of the optical potential, and the interconnection between the surface potential and the ⁶He breakup channels are discussed.     

Analysis of (π K<Superscript>+</Superscript>) and (K<Superscript>-</Superscript>, K<Superscript>+</Superscript>) hypernuclear production spectra in distorted-wave impulse approximation

We study the hyperon-nucleus potential with distorted-wave impulse wave approximation (DWIA) using the Green's function method. In order to include the nucleon and hyperon potential effects in Fermi averaging, we introduce the local optimal momentum approximation of target nucleons. We can describe the quasi-free Λ , Σ and Ξ production spectra in a better way than in the standard Fermi-averaged t -matrix treatments.     

Semiclassical description of the <Superscript>6</Superscript>He+<Superscript>12</Superscript>C elastic scattering

The results of the elastic scattering of ⁶He+¹²C systemat E _Lab = 18 MeV by using the barrier and internal wave decomposition of the S-matrix element within the framework of the WKB method are presented. This is the first detailed study for the interaction of the exotic ⁶He nucleus on different stable nuclei by using a semiclassicalmethod. In this paper, we show that in order to obtain the elastic scattering cross section of the ⁶He+¹²C systemat energies close to the Coulomb barrier, it is vitally important to take into account the inner complex turning points in the calculations and the tunneling effects play a crucial role to explain the experimental data. The semiclassical results are compared with the experimental data as well as the quantum-mechanical one.     

Na<Superscript>+</Superscript>/K<Superscript>+</Superscript> selectivity in the formation of ion pairs in aqueous solutions

The integral equations of liquids (RISM) and molecular dynamics method were used to calculate the mean force potential for the SO₃ and COO hydrophilic groups and the CH₃ hydrophobic group in the acetate, methyl sulfonate, and hydrosulfate anions, which form ion pairs with sodium and potassium cations in water. The carboxyl group selectively binds sodium ions from solutions containing Na⁺ and K⁺ ions, in spite of their equal charges, because the potassium ion experiences stronger steric hindrances near this group compared with sodium. The biophysical consequences of the revealed selectivity are discussed.     

Unexpected transparency in the scattering of fragile <Superscript>6</Superscript>Li and <Superscript>6</Superscript>He Nuclei

It is found that the scattering of the fragile nucleus ⁶Li from ¹²C and ¹⁶O is unexpectedly transparent. It is shown that the internal-wave contribution is significantly large in the scattering, which suggests that some transparency could persist in the scattering involving the fragile nucleus ⁶He.     

Low-spin states in <Superscript>182</Superscript>Os and K<Superscript>π</Superscript> = 0<Superscript>+</Superscript>, 2<Superscript>+</Superscript> excited bands

Excited states in ¹⁸²Os were populated by the β⁺/EC decay of ¹⁸²Ir following mass separation. Gamma-ray and conversion electron spectroscopy techniques were employed. Monopole (E0) contributions were determined in transitions populating the ground-state band. A systematic study of the low-spin structures in the Os isotopes is presented and a detailed analysis in the framework of a microscopic configuration mixing approach is performed.     

Serotonin-mediated modulation of Na<Superscript>+</Superscript>/K<Superscript>+</Superscript> pump current in rat hippocampal CA1 pyramidal neurons

Background  

The aim of this study was to investigate whether serotonin (5-hydroxytryptamine, 5-HT) can modulate Na⁺/K⁺ pump in rat hippocampal CA1 pyramidal neurons.     

Reaction mechanism of <Superscript>6</Superscript>Li scattering at 600 MeV

Elastic scattering and inclusive breakup of ⁶Li particles on ¹²C, ⁵⁸Ni, ⁹⁰Zr, and ²⁰⁸Pb targets are measured at 100A MeV. The elastic scattering data are compared with single channel and Coupled Discretized Continuum Channels calculations. The coupling-effect between the elastic and the breakup channels is important even at an incident energy of 100A MeV and cannot be neglected. The inclusive breakup data are investigated for orbital dispersion effects which are found to be less significant at 100A MeV. The longitudinal momentum distributions are broader than predicted by theoretical expectations. Received: 17 December 1999 / Revised version: 9 February 2000     

Aspects of radiative K<Superscript>+</Superscript><Subscript>e3</Subscript> decays

We re-investigate the radiative charged kaon decay K^±→π⁰e^±ν_eγ [K_e3γ ^±] in chiral perturbation theory, merging the chiral expansion with Low’s theorem. We thoroughly analyze the precision of the predicted branching ratio relative to the non-radiative decay channel. Structure dependent terms and their impact on differential decay distributions are investigated in detail, and the possibility to see effects of the chiral anomaly in this decay channel is emphasized. PACS 13.20.Eb; 11.30.Rd; 12.39.Fe     

The pp→K<Superscript>+</Superscript><Emphasis Type="Italic">Σ</Emphasis><Superscript>+</Superscript>n cross-section from missing-mass spectra

We utilize existing inclusive data on K⁺-meson momentum spectra of the reaction pp→K ⁺ X at T _p = 2.3-2.85GeV to deduce total cross-sections for pp→K ⁺ Σ ⁺ n. The method used to extract those cross-sections is explained and discussed in detail. Our result for T _p = 2.85GeV is consistent with the data point from a direct measurement at the same beam energy. The cross-section obtained for T _p = 2.3GeV is with 13.7±2.3μb considerably smaller than the value found in a recent experiment by the COSY-11 Collaboration at a somewhat lower beam energy, indicating that the pp→K ⁺ Σ ⁺ n reaction cross-section could exhibit a rather unusual energy dependence.     

Evolution of Airy structure in <Superscript>12</Superscript>C(<Superscript>12</Superscript>C, <Superscript>12</Superscript>C)<Superscript>12</Superscript>C between 5 and 10 MeV/A

We investigate the properties of a global optical potential, which describes the ¹²C + ¹²C elastic-scattering data between 70 and 130 MeV, within the nearside/farside and barrier-wave/internal-wave decomposition techniques. Particular emphasis is laid on the discussion of the incomplete absorption features of this system, and especially on the properties of the Airy minima which are observed in the experimental excitation function. The complicated angular and energy evolution of the data is explained in terms of the interference of a small set of scattering subamplitudes with a much simpler behavior.Received: 2 September 2003, Revised: 25 September 2003, Published online: 5 February 2004PACS: 24.10.-i Nuclear reaction models and methods - 24.10.Ht Optical and diffraction models - 25.70.Bc Elastic and quasielastic scattering     

Momentum distributions of <Superscript>4</Superscript>He nuclei from the <Superscript>6</Superscript>He and <Superscript>6</Superscript>Li breakup

Experimental data on the momentum distributions of ⁴He nuclei originating from ⁶He and ⁶Li breakup on various targets are presented over a wide beam energy range. The experiment with ⁶He was performed at the DRIBs accelerator complex for radioactive beams at the Joint Institute for Nuclear Research (JINR, Dubna). The intensity of the ⁶He beam used was 5 × 10⁶ particles per second and its energy was 10 MeV per nucleon. The momentum distributions of breakup products were measured by means of the MSP-144 magnetic spectrometer. The distribution width was shown to be virtually independent of the target mass. A small value of this width, σ ～ 28 MeV/c, confirms the presence of a halo in ⁶He. The measurements performed with ⁶Li beams of energy 18 and 46 MeV per nucleon at the U-400M accelerator yielded a width value of σ ～ 50 MeV/c for the momentum distributions of ⁴He nuclei, which is intermediate between that for ⁶He and those for stable nuclei. A compilation of the widths of the momentum distributions of fragments originating from the breakup of various nuclei is presented versus the binding energy of one or two neutrons in these nuclei, the target mass and the projectile energy.     

Effect of high doses of N<Superscript>+</Superscript>, N<Superscript>+</Superscript> + Ni<Superscript>+</Superscript>, and Mo<Superscript>+</Superscript> + W<Superscript>+</Superscript> ions on the physicomechanical properties of TiNi

The surface layer of an equiatomic TiNi alloy, which exhibits the shape memory effect in the martensitic state, is modified with high-dose implantation of 65-keV N⁺ ions (the implantation dose is varied from 10¹⁷ to 10¹⁸ ions/cm²). TiNi samples are implanted by N⁺, Ni⁺-N⁺, and Mo⁺-W⁺ ions at a dose of 10¹⁷–10¹⁸ cm⁻² and studied by Rutherford backscattering, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction (glancing geometry), and by measuring the nanohardness and the elastic modulus. A Ni⁺ concentration peak is detected between two maxima in the depth profile of the N⁺ ion concentration. X-ray diffraction (glancing geometry) of TiNi samples implanted by Ni⁺ and N⁺ ions shows the formation of the TiNi (B2), TiN, and Ni₃N phases. In the initial state, the elastic modulus of the samples is E = 56 GPa at a hardness of H = 2.13 ± 0.30 GPa (at a depth of 150 nm). After double implantation by Ni⁺-N⁺ and W⁺-Mo⁺ ions, the hardness of the TiNi samples is ∼2.78 ± 0.95 GPa at a depth of 150 nm and 4.95 ± 2.25 GPa at a depth of 50 nm; the elastic modulus is 59 GPa. Annealing of the samples at 550°C leads to an increase in the hardness to 4.44 ± 1.45 GPa and a sharp increase in the elastic modulus to 236 ± 39 GPa. A correlation between the elemental composition, microstructure, shape memory effect, and mechanical properties of the near-surface layer in TiNi is found.