Sudbury project (University of Muenster-Ontario Geological Survey): New investigations on Sudbury breccia

Sudbury breccias occur as discordant dike breccias within the footwall rocks of the Sudbury structure, which is regarded as the possible remnant of a multiring basin. Exposures of Sudbury breccias in the North Range are known up to a radial distance of 60-80 km from the Sudbury Igneous Complex (SIC). The breccias appear more frequent within a zone of 10 km adjacent to the SIC and a further zone located about 20-33 km north of the structure. From differences in the structure of the breccias, as for example the size of the breccia dikes, contact relationships between breccia and country rock as well as between different breccia dikes, fragment content, and fabric of the ground mass, as seen in this section, the Sudbury Breccias have been classified into four different types. (1) Early breccias with a clastic/crystalline matrix comprise small dikes ranging in size from approx. 1 cm to max. 20 cm. (2) Polymict breccias with a clastic matrix represent the most common type of Sudbury breccia. The thickness of the dikes varies from several tens of centimeters to a few meters but can also extend to more than 100 m in the case of the largest known breccia dike. Contacts with country rock are sharp or gradational. Heterogenous matrix consisting of a fine-grained rock flour displays nonoriented textures as well as extreme flow lines. Chemical analysis substantiates at least some mixing with allochthonous material. (3) Breccias with a crystalline matrix are a subordinate type of Sudbury breccia. According to petrographical and chemical differences, three subtypes have been separated. (4) Late breccias with a clastic matrix are believed to represent the latest phase of brecciation. Two subtypes have been distinguished due to differences in the fragment content

Enantioselective Total Synthesis of (+)-Cassiol

An enantioselective total synthesis of (+)-cassiol is reported. The complex derived from Pd-2(pmdba)(3) and enantiopure t-BuPHOX ligand catalyzes enantioconvergent decarboxylative alkylation to generate the quaternary carbon stereocenter at an early stage. The overall synthetic strategy involves a convergent late-stage coupling of two fragments. The synthesis features a longest linear sequence of eight steps

Coordinate-space approach to the bound-electron self-energy: Self-Energy screening calculation

The self-energy screening correction is evaluated in a model in which the effect of the screening electron is represented as a first-order perturbation of the self energy by an effective potential. The effective potential is the Coulomb potential of the spherically averaged charge density of the screening electron. We evaluate the energy shift due to a $1s_{1/2}$, $2s_{1/2}$, $2p_{1/2}$, or $2p_{3/2}$ electron screening a $1s_{1/2}$, $2s_{1/2}$, $2p_{1/2}$, or $2p_{3/2}$ electron, for nuclear charge Z in the range $5 \le Z\le 92$. A detailed comparison with other calculations is made.Comment: 54 pages, 10 figures, 4 table

High Rate Performance of Drift Tubes

This article describes calculations and measurements of space charge effects due to high rate irradiation in high resolution drift tubes. Two main items are studied: the reduction of the gas gain and changes of the drift time. Whereas the gain reduction is similar for all gases and unavoidable, the drift time changes depend on the kind of gas that is used. The loss in resolution due to high particle rate can be minimized with a suitable gas. This behaviour is calculable, allowing predictions for new gas mixtures.Comment: 20 pages, submitted to Nuclear Instruments and Methods

Convergence Acceleration Techniques

This work describes numerical methods that are useful in many areas: examples include statistical modelling (bioinformatics, computational biology), theoretical physics, and even pure mathematics. The methods are primarily useful for the acceleration of slowly convergent and the summation of divergent series that are ubiquitous in relevant applications. The computing time is reduced in many cases by orders of magnitude.Comment: 6 pages, LaTeX; provides an easy-to-understand introduction to the field of convergence acceleratio

Two-Loop Bethe Logarithms

We calculate the two-loop Bethe logarithm correction to atomic energy levels in hydrogen-like systems. The two-loop Bethe logarithm is a low-energy quantum electrodynamic (QED) effect involving multiple summations over virtual excited atomic states. Although much smaller in absolute magnitude than the well-known one-loop Bethe logarithm, the two-loop analog is quite significant when compared to the current experimental accuracy of the 1S-2S transition: it contributes -8.19 and -0.84 kHz for the 1S and the 2S state, respectively. The two-loop Bethe logarithm has been the largest unknown correction to the hydrogen Lamb shift to date. Together with the ongoing measurement of the proton charge radius at the Paul Scherrer Institute its calculation will bring theoretical and experimental accuracy for the Lamb shift in atomic hydrogen to the level of 10^(-7).Comment: 4 pages, RevTe

Sensitivity to new physics: a_e vs. a_mu

At present it is generally believed that ``new physics'' effects contribute to leptonic anomalous magnetic moment, a_l, via quantum loops only and they are proportional to the squared lepton mass, (m_l)^2. An alternative mechanism for a contribution by new physics is proposed. It occurs at the tree level and exhibits a linear rather than quadratic dependence on m_l. This leads to a much larger sensitivity of a_e to the new physics than was expected so far.Comment: 4 pages, 2 figure

Screened self-energy correction to the 2p3/2-2s transition energy in Li-like ions

We present an ab initio calculation of the screened self-energy correction for (1s)^2 2p3/2 and (1s)^2 2s states of Li-like ions with nuclear charge numbers in the range Z = 12-100. The evaluation is carried out to all orders in the nuclear-strength parameter Z \alpha. This investigation concludes our calculations of all two-electron QED corrections for the 2p3/2-2s transition energy in Li-like ions and thus considerably improves theoretical predictions for this transition for high-Z ions

Phenomenology of a String-Inspired Supersymmetric Model with Inverted Scalar Mass Hierarchy

Supersymmetric (SUSY) models with heavy sfermions ($m_{\tilde{f}} \sim 10$ TeV) in the first two generations and the third generation sfermion masses below 1 TeV can solve the SUSY flavor and the CP problems as well as satisfy naturalness constraints. We study the phenomenology of a string-inspired scenario and compare it with the minimal supergravity unified model (mSUGRA). The SUSY trilepton signature at the upgraded Tevatron, the $b\to s\gamma$ branching fraction and the neutralino dark matter relic density in this model can differ significantly from the mSUGRA model.Comment: Version to appear in Physics Letters