Theoretical LSP detection rates for <Superscript>71</Superscript>Ga, <Superscript>73</Superscript>Ge,and <Superscript>127</Superscript>I dark-matter detectors

The low-energy structure of the dark-matter detector nuclei ⁷¹Ga, ⁷³Ge, and ¹²⁷I has been studied by using the microscopic quasiparticle-phonon model. The resulting ground states have been used to calculate theoretical predictions for detection rates of the lightest supersymmetric particle (LSP) in experiments studying elastic scattering of an LSP from an atomic nucleus. The highest rate, approximately 0.27 yr^?1kg^?1, among all the adopted SUSY parameters and renormalization schemes was provided by ¹²⁷I at the zero limit of the detector energy threshold.     

The Calcium Carbonate Geological Samples Study by <Superscript>3</Superscript>He NMR

Geological samples of calcium carbonates (CaCO₃) were investigated by ³He NMR, nitrogen porosimetry, X-ray diffraction and electron microscopy methods. The integral porosity of the samples was obtained by ³He nuclear magnetic resonance method and compared with nitrogen adsorption isotherms data. The advantages of ³He porometry method are discussed.     

Investigation of the Mn-doped compound CuGaTe<Subscript>2</Subscript> by <Superscript>63</Superscript>Cu AND <Superscript>69</Superscript>Ga nuclear magnetic resonance techniques

The synthesized base compound CuGaTe₂ and the Mn-doped compounds Cu_0.97Ga_0.97Mn_0.06Te₂ and Cu_0.93Ga_0.93Mn_0.14Te₂ have been investigated by using ⁶³Cu and ⁶⁹Ga NMR spectroscopy. The NMR spectra obtained testify to substantial structural distortions near the cationic positions in the crystal lattice of Mndoped samples. The constants of quadrupole coupling between ⁶³Cu and ⁶⁹Ga nuclei in the compounds investigated have been estimated.     

Resonance Structure of the Charge-Exchange Strength Function and Neutrino-Capture Cross Sections for the Isotopes <Superscript>71</Superscript>Ga, <Superscript>98</Superscript>Mo,and <Superscript>127</Superscript>I

A resonance structure of the charge-exchange strength function S(E) and its effect on the neutrino-capture cross sections for the isotopes ⁷¹Ga, ⁹⁸Mo, and ¹²⁷I are studied within the self-consistent theory of finite Fermi systems. The calculation of the strength function S(E) takes into account Gamow–Teller, analog, and so-called lower lying pygmy resonances. The neutrino-capture cross sections σ(E) for the above three isotopes are calculated with allowance for the resonance structure of the strength function S(E), and the effect of each resonance on the energy dependence σ(E) is analyzed. It is found that all charge-exchange resonances in the strength function S(E) should be taken into account in calculating the neutrino-capture cross section σ(E) for the isotopes ⁷¹Ga, ⁹⁸Mo, and ¹²⁷I. The disregard of even highlying resonances leads to a substantial underestimation of the cross section σ(E), and this may affect the interpretation of respective experimental data.     

Photophysical Properties of Rare Earth (Eu<Superscript>3+</Superscript>, Sm<Superscript>3+</Superscript>, Tb<Superscript>3+</Superscript>) Complex Covalently Immobilized in Hybrid Si-O-B Xerogels

The molecular linkage (phenSi) from functionalized 5-amino-1,10-phenanthroline (PhenNH₂) by 3-(triethoxysilyl)-propyl isocyanate (TESPIC) is to construct the rare earth (Sm³⁺, Eu³⁺, Tb³⁺) center covalently immobilized in the hybrid xerogels of Si-O-B through the cohydrolysis and copolycondensation process between different alkoxide precursors of them (tetraethoxysilane (TEOS), tri-n-butylborate (TBB)). NMR, FTIR and ultraviolet absorption are measured to confirm the obtained materials. X-ray diffraction patterns revealed the hybrid materials are amorphous. Scanning electronic microscopy images show the stripe microstructure without phase separation phenomenon in the obtained hybrid materials. The covalently bonded Si-O-B hybrid xerogel presents the similar photoluminescent behavior to the pure Si-O-Si hybrid xerogels, which indicates that Si-O-B hybrid xerogel is a suitable system for the luminescence of RE³⁺.     

<Superscript>23</Superscript>Na NMR in binary lithium-sodium cobaltite

Li_0.48Na_0.35CoO₂ lithium-sodium cobaltite was studied by means of wide-line ²³Na and ⁷Li NMR. A series of quantum-chemical calculations allowed to us determine the optimum positions of Li and Na atoms, to construct a map of the densities of electronic states near the Fermi level, and to estimate the electric field gradient on the Na nuclei. The results from these calculations are compared with experimental data from NMR and X-ray photoelectron spectroscopy     

Multinuclear MAS NMR Investigation of Sol-Gel and Ball-Milled Nanocrystalline Ga<Subscript>2</Subscript>O<Subscript>3</Subscript>

⁷¹Ga magic-angle spinning (MAS) nuclear magnetic resonance (NMR) has been used to characterize the structural evolution of nanocrystalline Ga₂O₃ samples prepared by sol-gel and ball-milling techniques. ²⁹Si and ²⁷Al MAS NMR have also been used to characterize silica and alumina Zener pinning phases. ⁷¹Ga NMR parameters are reported for the α- and β-Ga₂O₃ phases, and more tentatively for the δ-Ga₂O₃ phase. By simulating the octahedrally coordinated gallium NMR line of β-Ga₂O₃ using Gaussian distributions in χ_Q, the extent of disorder in the Ga₂O₃ crystallites has been quantified. The ball-milled samples contain much more inherent disorder than the sol-gel samples in the nano-phase, which was observed from simulations of the ⁷¹Ga MAS NMR spectra. The silica pinning phase produced highly crystalline and densely aggregated nanocrystalline Ga₂O₃, as well as the smallest nanocrystal sizes. Authors' address: Mark E. Smith, Department of Physics, University of Warwick, Coventry CV4 7AL, UK     

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.     

Determination of <Superscript>68</Superscript>Ga production parameters by different reactions using ALICE and TALYS codes

Gallium-68 (T _1/2 = 68 min, I _β+ = 89%) is an important positron-emitting radionuclide for positron emission tomography and used in nuclear medicine for diagnosing tumours. This study gives a suitable reaction to produce ⁶⁸Ga. Gallium-68 excitation function via ⁶⁸Zn(p, n)⁶⁸Ga, ⁶⁸Zn(d, 2n)⁶⁸Ga, ⁷⁰Zn(p, 3n)⁶⁸Ga and ⁶⁵Cu(α, n)⁶⁸Ga reactions were calculated by ALICE-91 and TALYS-1.0 codes. The calculated excitation function of ⁶⁸Zn(p, n)⁶⁸Ga reaction was compared with the reported measurement and evaluations. Requisite thickness of the targets was obtained by SRIM code for each reaction. The ⁶⁸Ga production yield was evaluated using excitation function and stopping power.      

Further study and analysis of the <Superscript>7</Superscript>Li on <Superscript>56</Superscript>Fe reaction at 50 MeV incident energy

We present deuteron and triton spectra measured at 12 laboratory angles from the reaction of 50 MeV ⁷Li on ⁵⁶Fe together with evaporative components as modeled by CASCADE and fitted to the backward angle data. The deuteron and triton “break-up” spectra obtained by subtracting the evaporative components from the measured spectra are also presented. The break-up of the ⁷Li projectile near the surface occurs with high probability and the major fraction of the break-up cross-section is taken by (⁷Li,α) transfer process. A crude estimate of the fraction of the total cross-section is found to be of the same order of magnitude as the overall spectroscopic factor determined by the diffraction model. The value of the estimated fraction of total cross section at 50 MeV incident energy is compared to that at 68 MeV incident energy for the same reaction. However, these values of estimated fraction of total cross section are found very much consistent with the measured yields at both incident energies. The importance of the level density parameter in locating the maximum of excitation energy is indicated in the diffraction model.