Physics of EtaPrime->Pi+Pi-Eta and EtaPrime->Pi+Pi-Pi0 decays

The article describes experimental status of EtaPrime->Pi+Pi-Eta and EtaPrime->Pi+Pi-Pi0 decays. A theoretical framework used for description of the decays mechanism is also reviewed. The possibilities for the measurements with WASA-at-COSY are mentioned.Comment: Proceedings from Symposium on Meson Physics at COSY-11 and WASA-at-COSY, Cracow, 17-22 June 200

Leading Modes of the 3pi0 production in proton-proton collisions at incident proton momentum 3.35GeV/c

This work deals with the prompt pp-->pp3pi0 reaction where the 3pi0 do not origin from the decay of narrow resonances like \eta(547), \omega(782), \eta'(958). The reaction was measured for the proton beam momentum of 3.35GeV/c with the WASA-at-COSY detector setup. The dynamics of the reaction is investigated by Dalitz and Nyborg plots studies. The reaction is described by the model assuming simultaneous excitation of two baryon resonances \Delta(1232) and N*(1440) where resonances are identified by their unique decays topology on the missing mass of two protons MMpp dependent Dalitz and Nyborg plots. The ratio R=\Gamma(N*(1440)->N\pi\pi)/\Gamma(N*(1440)->\Delta(1232)\pi->N\pi\pi)= 0.039 +- 0.011(stat.) +- 0.008(sys.) is measured for the first time in a direct way. It shows that the {N*(1440)->\Delta(1232)\pi->N\pi\pi} decay is a leading mode of 3pi0 production. It is also shown that the MMpp is very sensitive to the structure of the spectral line shape of the N*(1440) resonance as well as on the interaction between the \Delta(1232) and N*(1440) resonances. The multipion spectroscopy - a precision tool to directly access the properties of baryon resonances is considered. The pp-->pp\eta(3pi0) reaction was also measured simultaneously. It is shown that the {\eta} production mechanism via N*(1535) is 43.4 +- 0.8(stat.) +- 2.0(sys.) of the total production, for the {\eta} momentum in the CM system q_\eta^CM=0.45-0.7GeV/c. First time momentum dependence of the {\eta} angular distribution is seen, the strongest effect is observed for the cos(\theta_\eta^CM) distribution.Comment: PhD Thesis prepared at the Nuclear Physics Department of the Jagiellonian University, Cracow, Poland, 201

Synthesis of novel room temperature chiral ionic liquids. application as reaction media for the heck arylation of aza-endocyclic acrylates.

New achiral and chiral RTILs were prepared using novel and/or optimized synthetic routes. These new series of imidazolinium, imidazolium, pyridinium and nicotine-derived ionic liquids were fully characterized including differential scanning calorimetry (DSC) analysis. The performance of these achiral and chiral room temperature ionic liquids (RTILs) was demonstrated by means of the Heck arylation of endocyclic acrylates employing arenediazonium salts and aryl iodides. The Heck arylations performed in the presence of these ionic entities, either as a solvent or as an additive, were effective leading to complete conversion of the substrate and good to excellent yield of the Heck adduct. In spite of the good performances, no asymmetric induction was observed in any of the cases studied. Two new diastereoisomeric NHC-palladium complexes were prepared in good yields from a chiral imidazolium salt and their structure characterized by X-ray diffraction. Overall, the Heck arylations employing arenediazonium tetrafluoroborates in RTILs were more effective than the traditional protocols employing aryl iodides in terms of reactivity and yields

Detection and imaging of the oxygen deficiency in single crystalline YBa2_{\text{2}}Cu3_{\text{3}}O7−δ_{\text{7}-\delta} thin films using a positron beam

Single crystalline YBa$_{\text{2}}$Cu$_{\text{3}}$O$_{\text{7}-\delta}$ (YBCO) thin films were grown by pulsed laser deposition (PLD) in order to probe the oxygen deficiency $\delta$ using a mono-energetic positron beam. The sample set covered a large range of $\delta$ (0.191<$\delta$<0.791) yielding a variation of the critical temperature $T_{\text{c}}$ between 25 and 90\,K. We found a linear correlation between the Doppler broadening of the positron electron annihilation line and $\delta$ determined by X-ray diffraction (XRD). Both, the origin of the found correlation and the influence of metallic vacancies, were examined with the aid of ab-initio calculations that allowed us (i) to exclude the presence of Y vacancies and (ii) to ensure that positrons still probe $\delta$ despite the potential presence of Ba or Cu vacancies. In addition, by scanning with the positron beam the spatial variation of $\delta$ could be analyzed. It was found to fluctuate with a standard deviation of up to $0.079(5)$ within a single YBCO film

Nanostructure phase and interface engineering via controlled Au self-assembly on GaAs(001) surface

We have investigated the temperature-dependent morphology and composition changes occurring during a controlled self-assembling of thin Au film on the Gallium arsenide (001) surface utilizing electron microscopy at nano and atomic levels. It has been found that the deposition of 2 ML of Au at a substrate temperature lower than 798 K leads to the formation of pure Au nanoislands. For the deposition at a substrate temperature of about 798 K the nanostructures of the stoichiometric AuGa phase were/had been grown. Gold deposition at higher substrate temperatures results in the formation of octagonal nanostructures composed of an AuGa2 alloy. We have proved that the temperature-controlled efficiency of Au-induced etching-like of the GaAs substrate follows in a layer-by-layer manner leading to the enrichment of the substrate surface in gallium. The excess Ga together with Au forms liquid droplets which, while cooling the sample to room temperature, crystallize therein developing crystalline nanostructures of atomically-sharp interfaces with the substrate. The minimal stable cluster of 3 atoms and the activation energy for the surface diffusion Ed=0.816+-0.038eV was determined. We show that by changing the temperature of the self-assembling process one can control the phase, interface and the size of the nanostructures formed

Diodes with Breakdown Voltages Enhanced by the Metal-Insulator Transition of LaAlO3_3-SrTiO3_3 Interfaces

Using the metal-insulator transition that takes place as a function of carrier density at the LaAlO$_3$-SrTiO$_3$ interface, oxide diodes have been fabricated with room-temperature breakdown voltages of up to 200 V. With applied voltage, the capacitance of the diodes changes by a factor of 150. The diodes are robust and operate at temperatures up to 270 C

Electric-field-induced pyroelectric order and localization of the confined electrons in LaAlO3/SrTiO3 heterostructures

With infrared ellipsometry, x-ray diffraction, and electric transport measurements we investigated the electric-field-effect on the confined electrons at the LaAlO3/SrTiO3 interface. We obtained evidence that the localization of the electrons at low temperature and negative gate voltage is induced, or at least strongly enhanced, by a pyroelectric phase transition in SrTiO3 which strongly reduces the lattice polarizability and the subsequent Coulomb screening. In particular, we show that the charge localisation and the polar order of SrTiO3 both develop below about 50 K and exhibit similar, unipolar hysteresis loops as a function of the gate voltage. Our findings suggest that the pyroelectric order also plays an important role in the quantum phase transition at very low temperatures where superconductivity is suppressed by an electric field.Comment: 5 pages, 4 figures, supplementary materia

Into the Origin of Electrical Conductivity for the Metal-Semiconductor Junction at the Atomic Level

The metal-semiconductor (M-S) junction based devices are commonly used in all sorts of electronic devices. Their electrical properties are defined by the metallic phase properties with a respect to the semiconductor used. Here we make an in-depth survey on the origin of the M-S junction at the atomic scale by studying the properties of the AuIn2 nanoelectrodes formed on the InP(001) surface by the in situ electrical measurements in combination with a detailed investigation of atomically resolved structure supported by the first-principle calculations of its local electrical properties. We have found that a different crystallographic orientation of the same metallic phase with a respect to the semiconductor structure influences strongly the M-S junction rectifying properties by subtle change of the metal Fermi level and influencing the band edge moving at the interface. This ultimately changes conductivity regime between Ohmic and Schottky type. The effect of crystallographic orientation has to be taken into account in the engineering of the M-S junction-based electronic devices