Time-of-flight studies of emission of μt from frozen hydrogen films

In recent TRIUMF experiments, a μ^- beam is stopped in a solid hydrogen film with a small fraction of T₂. The Ramsauer-Townsend (RT) mechanism allows μt to escape into vacuum with a few eV of energy. To study the emission process, an imaging system was used to determine the position of muon decays. Experimental histograms are in good agreement with a Monte Carlo simulation. This revised version was published online in August 2006 with corrections to the Cover Date.     

Resonant formation measurements of dt\mu via time of flight

Solid hydrogen in the form of an inhomogeneous layered target offers several experimental advantages when compared with liquid or gas. Beams of non-thermalized muonic hydrogen atoms allow us to explore resonant molecular ion formation processes near eV kinetic energies. Isotopically specific layers make it possible to separate competing and confusing interactions and to employ the time of flight for comparison with predictions based on theoretical energy dependences. Unambiguous charged fusion product detection simplifies absolute intensity measurements. The systematic uncertainties encountered in resonant molecular ion formation measurements, using solid hydrogen target layers, are being investigated with simulations which use the many calculated energy-dependent rates and cross-sections which are now available. The importance of the rates for processes such as muon transfer and elastic scattering are discussed, and results of some recent analyses are presented. This revised version was published online in August 2006 with corrections to the Cover Date.     

Some Remarks on Distributed PCHD-Systems

Port controlled Hamiltonian systems with dissipation are a well known tool for the modeling and the controller design for plants, described by nonlinear ordinary differential equations. This contribution presents a possible extension to systems, described by partial differential equations, where the state manifold and the input space of the ODE case are replaced by new geometric structures. This approach takes dissipative effects into account and shows, how distributed ports can be introduced. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Frozen‐In Magnetic Order in Uniaxial Magnetic Gels: Preparation and Physical Properties

We describe the preparation and characterization of uniaxial magnetic gels. Fibril formation of the embedded magnetic particles generates easily detectable magnetic and optical anisotropies. A finite magnetization is frozen‐in and leads to a ferromagnetic‐like response in small homogeneous external magnetic fields. We present, for the first time, frequency dependent measurements of the shear modulus G′. Despite their optical and magnetic anisotropy, the gels are mechanically isotropic.

The time‐dependent G′ for a ferrogel in the parallel orientation in a homogeneous field of 200 mT.     

A Novel Method for the Introduction of a 5β‐Methyl Group into 4,5α‐Epoxymorphinan‐6‐ones via the Enol Ether

The introduction of a 5β‐methyl group into 14‐alkoxy substituted naltrexone derivatives was accomplished via the enol ethers 2a and 2b by means of the `LICKOR' (t‐BuLi/t‐BuOK) base system. According to this new method, the highly selective δ‐opioid antagonist HS 378 ( 7b ) and its 14‐methoxy analog 7a , both originally prepared in nine steps from thebaine, are now available in only four steps.