Enhancement of the electric dipole moment of the electron in PbO

The a(1) state of PbO can be used to measure the electric dipole moment of the electron d_e. We discuss a semiempirical model for this state, which yields an estimate of the effective electric field on the valence electrons in PbO. Our final result is an upper limit on the measurable energy shift, which is significantly larger than was anticipated earlier: $2|W_d|d_e \ge 2.4\times 10^{25} \textrm{Hz} [ \frac{d_e}{e \textrm{cm}} ]$.Comment: 4 pages, revtex4, no figures, submitted to PR

Effect of Plasma Irradiation on CdI2Cd I_2 films

The effect of plasma irradiation is studied systematically on a 4H polytype (002) oriented ${\rm CdI_2}$ stoichiometric film having compressive residual stress. Plasma irradiation was found to change the orientation to (110) of the film at certain moderate irradiation distances. A linear decrease in grain size and residual stress was observed with decreasing irradiation distance (or increasing ion energy) consistent with both structural and morphological observations. The direct optical energy gap ${\rm E_g}$ was found to increase linearly at the rate ${\rm 15\mu eV/atm}$ with the compressive stress. The combined data of present compressive stress and from earlier reported tensile stress show a consistent trend of ${\rm E_g}$ change with stress. The iodine-iodine distance in the unit cell could be responsible for the observed change in ${\rm E_g}$ with stress.Comment: 13 pages and 10 fi

A Necessary Condition for existence of Lie Symmetries in Quasihomogeneous Systems of Ordinary Differential Equations

Lie symmetries for ordinary differential equations are studied. In systems of ordinary differential equations, there do not always exist non-trivial Lie symmetries around equilibrium points. We present a necessary condition for existence of Lie symmetries analytic in the neighbourhood of an equilibrium point. In addition, this result can be applied to a necessary condition for existence of a Lie symmetry in quasihomogeneous systems of ordinary differential equations. With the help of our main theorem, it is proved that several systems do not possess any analytic Lie symmetries.Comment: 15 pages, no figures, AMSLaTe

Using Molecules to Measure Nuclear Spin-Dependent Parity Violation

Nuclear spin-dependent parity violation arises from weak interactions between electrons and nucleons, and from nuclear anapole moments. We outline a method to measure such effects, using a Stark-interference technique to determine the mixing between opposite-parity rotational/hyperfine levels of ground-state molecules. The technique is applicable to nuclei over a wide range of atomic number, in diatomic species that are theoretically tractable for interpretation. This should provide data on anapole moments of many nuclei, and on previously unmeasured neutral weak couplings

Enhancement of the electric dipole moment of the electron in BaF molecule

We report results of ab initio calculation of the spin-rotational Hamiltonian parameters including P- and P,T-odd terms for the BaF molecule. The ground state wave function of BaF molecule is found with the help of the Relativistic Effective Core Potential method followed by the restoration of molecular four-component spinors in the core region of barium in the framework of a non-variational procedure. Core polarization effects are included with the help of the atomic Many Body Perturbation Theory for Barium atom. For the hyperfine constants the accuracy of this method is about 5-10%.Comment: 8 pages, REVTEX, report at II International Symposium on Symmetries in Subatomic Physics, Seattle 199

One approach to the analytical solution of a two-dimensional nonstationary problem of heat conduction in regions with moving boundaries on the model of a half-space

With the use of the solution of the Dirichlet nonstationary problem with discontinuous unmixed boundary conditions on the surface of an isotropic half-space a two-dimensional model of the problem with a moving phase boundary is considered. The problem models, for example, the processes of freezing of moist ground or the processes of formation of ice in stagnant water if a temperature lower than the freezing temperature is prescribed on the boundary surface in a circular region of finite radius. The classical one-dimensional result follows as a particular case from solution of this problem for an infinite radius of the circle

A method of paired integral equations in the region of laplace transforms for solving nonstationary heat conduction problems with mixed discontinuous boundary conditions

On the basis of the method developed, the solutions of four problems of mathematical physics are obtained for an infinite plate (a plane layer of thickness z = h) with assignment of mixed discontinuous boundary conditions (BC) on one of the surfaces z = 0 of the plate and unmixed BC on the other surface z = 17

The WITCH experiment: Acquiring the first recoil ion spectrum

The standard model of the electroweak interaction describes beta-decay in the well-known V-A form. Nevertheless, the most general Hamiltonian of a beta-decay includes also other possible interaction types, e.g. scalar (S) and tensor (T) contributions, which are not fully ruled out yet experimentally. The WITCH experiment aims to study a possible admixture of these exotic interaction types in nuclear beta-decay by a precise measurement of the shape of the recoil ion energy spectrum. The experimental set-up couples a double Penning trap system and a retardation spectrometer. The set-up is installed in ISOLDE/CERN and was recently shown to be fully operational. The current status of the experiment is presented together with the data acquired during the 2006 campaign, showing the first recoil ion energy spectrum obtained. The data taking procedure and corresponding data acquisition system are described in more detail. Several further technical improvements are briefly reviewed.Comment: 11 pages, 6 figures, conference proceedings EMIS 2007 (http://emis2007.ganil.fr), published also in NIM B: doi:10.1016/j.nimb.2008.05.15