Limit theorems for a recursive maximum process with location-dependent periodic intensity-parameter

We investigate the recursive sequence Z _n : =  max {Z _n − 1,λ(Z _n − 1)X _n } where X _n is a sequence of iid random variables with exponential distributions and λ is a periodic positive bounded measurable function. We prove that the Césaro mean of the sequence λ(Z _n ) converges toward the essential minimum of λ. Subsequently we apply this result and obtain a limit theorem for the distributions of the sequence Z _n . The resulting limit is a Gumbel distribution.     

Precision measurements of Higgs-chargino couplings in chargino pair production at a muon collider

We study chargino pair production on the heavy Higgs resonances at a muon collider in the MSSM. At GeV cross sections up to 2 pb are reached depending on the supersymmetric scenario and the beam energy spread. The resonances of the scalar and pseudoscalar Higgs bosons may be separated for . Our aim is to determine the ratio of the chargino couplings to the heavy scalar and pseudoscalar Higgs boson independently of the specific chargino decay characteristics. The precision of the measurement depends on the energy resolution of the muon collider and on the error in the measurement of the cross sections of the non-Higgs channels including an irreducible standard model background. With a high energy resolution the systematic error can be reduced to the order of a few percent.Received: 6 March 2003, Revised: 21 May 2003, Published online: 3 July 2003     

Recent results from the TCV tokamak

During the first two years of operation, the TCV tokamak has produced a large variety of plasma shapes and magnetic configurations, with 1.0B _tor1.46T,I _p800kA,k2.05, –0.71. A new shape control algorithm, based on a finite element reconstruction of the plasma current in real time, has been implemented. Vertical growth rates up to 1000s^–1 have been stabilized using the external coil system. Ohmic H-modes with Troyon factors ( _tor aB/I _p) up to two and densities up to 2.25×10²⁰m^–3, corresponding to the Greenwald limit, have been obtained in diverted discharges. Limiter H-modes with line averaged electron densities up to 1.7×10²⁰m^–3 have been obtained in elongated D-shaped plasmas with 360 kAI _P600 kA.Presented at 17^th Symposium Plasma Physics and Technology, Prague, June 13–16, 1995.This work was partly supported by the Fonds National Suisse de la Recherche Scientifique.     

Quasicrystalline epitaxial single element monolayers on icosahedral Al-pd-mn and decagonal Al-ni-co quasicrystal surfaces

Single element quasicrystalline monolayers were prepared by deposition of antimony and bismuth on the fivefold surface of icosahedral Al71.5Pd21Mn8.5 and the tenfold surface of decagonal Al71.8Ni14.8Co13.4. Elastic helium atom scattering and low energy electron diffraction of the monolayers show Bragg peaks at the bulk derived positions of the clean surfaces, revealing highly ordered quasicrystalline epitaxial films. Their adatom densities of (0.9+/-0.2)x10(15) cm(-2) and (0.8+/-0.2)x10(15) cm(-2) on Al-Pd-Mn and Al-Ni-Co, respectively, correspond to roughly one adatom per Al atom of the quasicrystalline substrate surfaces.     

X-ray absorption and X-ray photoelectron spectroscopy of a rhodium colloid

Transition metal colloids are potential precursors of heterogeneous catalysts with application to selective chemical reactions. Sample preparation techniques are described. Experimental details are given of the characterization of these often air-sensitive particles by X-ray photoelectron and X-ray absorption spectroscopy. First results obtained with both techniques for a Rh-colloid show that the metal is mainly present in the zerovalent chemical state. But the spectra indicate further chemical states of Rh which can be assigned to the outermost metal atoms of the colloid interacting with organic ligands or to the educt Rh-halides.     

η3-Allyl[1,2-bis(diphenylphosphino)ethan]tricarbonylvanadium(0)-komplexe

The preparation, properties and spectroscopic investigation (IR, ¹H NMR, ³¹P NMR, MS) of η³-allyl[1,2-bis(diphenylphosphino)ethan]tricarbonylvanadium(0) compounds are reported.     

Organoarsen-Verbindungen : XXIV. Zur synthese der perhydro-1,3-azarsenine

The reaction of NaAsHR with ClCH₂CH₂CH₂NH₂ yields the corresponding secondary 3-aminopropylarsines, RAs(H)CH₂CH₂CH₂NH₂, which with aldehydes and ketones form the perhydro-1,3-azarsenines. The properties and reactivity of these heterocyclic compounds are described.