First result from the MTV experiment at TRIUMF searching T-violation in nuclear beta decay

The MTV experiment (Mott Polarimetry for T-Violation Experiment) is running from 2009 at TRIUMF, which aims to search a large non-standard T-Violation in polarized nuclear beta decay. Existence of transverse polarization of electrons emitted from polarized ⁸Li nuclei, which are produced at TRIUMF-ISAC and stopped inside an aluminum stopper, is investigated. We utilize a Mott polarimeter consists of a planer drift chamber, measuring backward scattering left-right asymmetry from a thin lead analyzer foil. In this paper, preliminary results from the first physics run performed in 2010 are described.     

Use of immobilized amyloglucosidase as chiral selector in chromatography. Immobilization and performance in liquid chromatography

Summary The enzyme amyloglucosidase was immobilized on oxidized DIOL silica and used to separate enantiomers of amino alcohols. The influence of pore size on enantioselectivity was studied and an optimum in the separation factors was found using 500 ? DIOL silica as the starting material. About twice the amount of the protein could be immobilized on the 500 ? DIOL silica material as on the 300 and 1000 ? materials. The immobilization procedure was easy to reproduce and no significant difference in the chromatographic behavior was observed between two amyloglucosidase columns produced in-house. The effect of solute structure on enantioselective retention was studied using a set of 10 closely related amino alcohols. High separation factors (α>2) were obtained and the efficiency of the amyloglucosidase columns was greater than 25 000 plates/m based on the last eluted enantiomer.     

Ion detection from beta decay and two-body decay experiments with laser-cooled atoms

Localized and cold samples of atoms produced with laser cooling and trapping techniques are a powerful tool for nuclear β-decay experiments. Recently we have concentrated on measurements of the momentum of the daughter ion produced, which leads to a variety of new observables. Angular distributions of the recoils with respect to the nuclear spin in β ⁺ decay are sensitive to non-standard model interactions. Measurements of the momentum of monoenergetic recoils from either electron capture or isomer γ decay would make it possible to search for particles with masses of 10s of keV.      

Gd3+ electron spin resonance spectroscopy on LaO1 ? x F x FeAs superconductors

We report an electron spin resonance (ESR) spectroscopy study on polycrystalline samples of the LaO_{1 ? x} F _x FeAs (x = 0 and 0.1) compound with small levels of Gd doping (2% and 5%). The Gd ESR signal is found to be sensitive to the magnetic phase transition from the paramagnetic to the spin density wave (SDW) state occurring in the parent LaO_{1 ? x} F _x FeAs compounds at T _SDW ?? 130 K. Interestingly, the analysis of the low-temperature ESR spectra of the c-axis oriented Gd_{1 ? y} La _y OFeAs samples gives evidence for the magnetically nonequivalent Gd sites and also for sites having a different local charge environment. The analysis of the temperature dependence of the ESR linewidths gives evidence for a coupling of the localized 4f electrons of Gd to the conduction electrons in the FeAs layers. The ESR data reveal that the fluorine substitution, which provides electron doping, suppresses the SDW order and enhances the density of states in the electronic bands stemming from the xz and yz orbital states of Fe to which the 4f electrons are most strongly coupled.     

Nuclear charge radii of 9,11Li: the influence of halo neutrons

The nuclear charge radius of 11Li has been determined for the first time by high-precision laser spectroscopy. On-line measurements at TRIUMF-ISAC yielded a 7Li-11Li isotope shift (IS) of 25 101.23(13) MHz for the Doppler-free [FORMULA: SEE TEXT]transition. IS accuracy for all other bound Li isotopes was also improved. Differences from calculated mass-based IS yield values for change in charge radius along the isotope chain. The charge radius decreases monotonically from 6Li to 9Li, and then increases from 2.217(35) to 2.467(37) fm for 11Li. This is compared to various models, and it is found that a combination of halo neutron correlation and intrinsic core excitation best reproduces the experimental results.     

Oxidation of some aromatic amines on the passivated hanging mercury drop electrode

It has been shown that a hanging mercury drop electrode of the Kemula type is a very convenient tool for studying the redox processes of organic substances in the positive potential range. Conditions influencing the oxidation process are discussed. The method described may prove to be an analytical tool for the determination of some aromatic amines.     

Quadrupole Moments of Na Isotopes

The electric quadrupole coupling constants eqQ/h of ²⁰Na (I ^π = 2⁺, T _1/2 = 449.7 ms), ²¹Na (I ^π = 3/2, T _1/2 = 22.49 s) and ²⁵Na (I ^π = 5/2, T _1/2 = 59.6 s) in single crystal ZnO and TiO₂ were precisely measured by applying the β-NMR technique. The ratio of the quadrupole moments between ²⁰Na (²⁵Na) and ²¹Na was determined to be 0.728 ± 0.023 (0.011 ± 0.002).     

The static Debye-Waller factor of defect-induced lattice displacements

The attenuation of Bragg scattering intensities due to static displacements is discussed for interstitially dissolved point-defects. It is shown that in the single defect approximation the static Debye-Waller factor (DWF) exp (–2L) decreases linearly with the defect concentrationc and quadratically with the scattering-vectorK (for smallK andc). From a model calculation of the displacements around H in Nb the static DWF is shown to be primarily due to the displacements closest to the impurity. Therefore the measurement of the static DWF can be used as a method to determine these displacements. From X-ray measurements of the integrated Bragg intensities of NbH _x single crystals we obtained the displacements of the four nearest neighbours around a tetrahedral interstitial site to beu ₁=0.1Å. This is in good agreement with the results of our model calculation.