Study of KS KL Coupled Decays and KL -Be Interactions with the CMD-2 Detector at VEPP-2M Collider

The integrated luminosity about 4000 inverse nanobarn of around phi meson mass ( 5 millions of phi mesons) has been collected with the CMD-2 detector at the VEPP-2M collider. A latest analysis of the KS KL coupled decays based on 30 % of available data is presented in this paper. The KS KL pairs from phi meson decays were reconstructed in the drift chamber when both kaons decayed into two charged particles. From a sample of 1423 coupled decays a selection of candidates to the CP violating KL into pi+ pi- decay was performed. CP violating decays were not identified because of the domination of events with a KL regenerating at the Be beam pipe into KS and a background from KL semileptonic decays. The regeneration cross section of 110 MeV/c KL mesons was found to be 53 +- 17 mb in agreement with theoretical expectations. The angular distribution of KS mesons after regeneration and the total cross section of KL for Be have been measured.Comment: 14 pages, 8 figure

New precise determination of the \tau lepton mass at KEDR detector

The status of the experiment on the precise $\tau$ lepton mass measurement running at the VEPP-4M collider with the KEDR detector is reported. The mass value is evaluated from the $\tau^+\tau^-$ cross section behaviour around the production threshold. The preliminary result based on 6.7 pb$^{-1}$ of data is $m_{\tau}=1776.80^{+0.25}_{-0.23} \pm 0.15$ MeV. Using 0.8 pb$^{-1}$ of data collected at the $\psi'$ peak the preliminary result is also obtained: $\Gamma_{ee}B_{\tau\tau}(\psi') = 7.2 \pm 2.1$ eV.Comment: 6 pages, 8 figures; The 9th International Workshop on Tau-Lepton Physics, Tau0

A selected bibliography on parameter optimization methods suitable for hybrid computation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68333/2/10.1177_003754976700800610.pd

Search for rare Phi decays in pi+ pi_ gamma final state

A search for phi radiative decays has been performed using a data sample of about 2.0 million phi decays collected by the CMD-2 detector at VEPP-2M collider in Novosibirsk. From the selected e+ e- -> pi+ pi- gamma events the following results were obtained: B(phi -> f0(980) gamma) < 1x10-4 for destructive and B(phi -> f0(980) gamma) < 7x10-4 for constructive interference with the Bremsstrahlung process respectively, B(phi -> gamma -> pi+ pi- gamma) 20 MeV, B(phi -> rho gamma) < 7x10-4. From the selected e+ e- -> mu+ mu- gamma events B(phi -> mu+ mu- gamma) = (2.3+-1.0)x10-5 has been obtained for E of gamma> 20 MeV. The upper limit on the P,CP-violating decay eta -> pi+ pi- has also been placed: B(eta -> pi+ pi-) < 9x10-4 . All upper limits are at 90 % C.L.Comment: 18 pages, 7 figure

First experimental results obtained using the highpower free electron laser at the siberian center for photochemical research

The first lasing near the wavelength of 140 µm was achieved in April 2003 using a high-power free electron laser (FEL) constructed at the Siberian Center for Photochemical Research. In this paper we briefly describe the design of the FEL driven by an accelerator–recuperator. Characteristics of the electron beam and terahertz laser radiation, obtained in the first experiments, are also presented in the paper.У Сибірському центрі фотохімічних досліджень навесні 2003 року отримана генерація випромінювання з довжиною хвилі 140 мкм на потужному лазері на вільних електронах (ЛВЕ). У роботі коротко описана конструкція ЛВЕ на базі прискорювача рекуператора і представлені результати вимірювання деяких параметрів електронного пучка і терагерцового випромінювання.В Сибирском центре фотохимических исследований весной 2003 года получена генерация излучения с длиной волны 140 мкм на мощном лазере на свободных электронах (ЛСЭ). В работе кратко описана конструкция ЛСЭ на базе ускорителя рекуператора и представлены результаты измерения некоторых параметров электронного пучка и терагерцового излучения

Structure and reactivity of metal ion species in high-silica zeolites

A review; in this chapter, the emphasis moves to reactivity at metal ion sites in zeolites. One of the recent trends in the development of heterogeneous catalysts is connected with metal-contg. zeolites. Metal cations can be introduced into a zeolite at the synthesis stage as well as via various methods of zeolite modification (such as liq.- or solid-state ion-exchange technique, chem. vapor deposition). There are now a no. of unique catalysts (esp. MFI zeolites-based ones) showing high activity and selectivity in the diverse processes. Typical examples of such catalysts and processes are: Ti-contg. zeolites (hydrocarbon oxidn. by hydrogen peroxide); Fe zeolites (direct oxidn. of benzene into phenol by nitrous monoxide); Zn and Ga zeolite (dehydrogenation and aromatization of alkanes) and Cu, Fe, and Co zeolites (SCR of NOx). [on SciFinder (R)

DFT study of oxygen-bridged Zn2+ ion pairs in Zn/ZSM-5 zeolites

A cluster model for Zn/ZSM-5 zeolite is proposed, which consists of an oxygen-bridged [Zn-O-Zn](2+) moiety attached to two framework aluminum ions of two adjacent ZSM-5 5-rings. Its stability and catalytic activity in ethane dehydrogenation were considered using the DFT method and compared with those for single Zn2+ ions in the same rings. It is shown that the oxygen-bridged Zn2+ pair is rather reactive towards ethane dissociation and that the rate-limiting step is release of hydroge

Spectroscopic identification of adsorption properties of Zn2+ ions at cationic positions of high-silica zeolites with distant placing of aluminium ions.

For Zn2+ cations in ZnZSM-5 zeolite unusual type of cationic positions, formed by two distantly placed framework aluminium atoms, is considered. Some extent of structural destabilization of cations in these cationic positions in comparison with traditional localization should result in promoted Lewis activity and adsorption activity of these sites. The last ones are manifested in the significantly increased IR low frequency shifts for adsorbed molecules and in their ability for heterolytic dissociation at elevating temperature. DFT cluster quantum chemical modeling of light alkane adsorption on Zn2+ in ZnZSM-5 zeolites confirms these conjectures in full agreement with recent experiments. Similar to the previously considered dihydrogen and methane molecule adsorption, we present here the calculations of ethane molecular and dissociative adsorption on these sites. It is shown that the unusually large ethane IR frequency shift recently observed in ZnZSM-5 zeolite can result from adsorptive interaction of C2H6 with Zn2+ stabilized in a cationic position with distantly placed aluminium ions. The dissociative adsorption of ethane molecules with the formation of bridged hydroxyl group and Zn–C2H5 structure is considered and an activation energy of ethylene formation from the alkyl fragment is evaluated

DFT cluster modeling of molecular and dissociative hydrogen adsorption on Zn2+ ions with distant placing of aluminum in the framework of high-silica zeolites

The problem of various cationic positions in zeolites with high Si/Al ratio in the framework is discussed. The statistical distribution of Al in the lattice of pentasils makes probable appearance of the structures with distant placing of 2 Al atoms. Cations, localized at such sites, should be very strong Lewis acids that are highly active in different chem. reactions. An example of such a site is considered for two Zn2+ ions stabilized in the zeolite fragment represented by 2 adjacent 5-membered rings sharing the common edge. DFT calcns. of mol. and dissociative H adsorption by such sites are in agreement with exptl. results. Adsorption of H by Zn ion at such sites results in an unusually large low-frequency shift of H-H stretching vibrations indicating essential activation of adsorbed H mol. The calcd. path of heterolytic dissociative adsorption of H and of the proton migration to the distantly placed basic oxygen of such acid-base pair are in agreement with the previously published DRIFT exptl. data