Search for f1(1285)→π+π−π0f_1(1285) \to \pi^+\pi^-\pi^0 decay with VES detector

The isospin violating decay $f_1(1285)\to\pi^+\pi^-\pi^0$ has been studied at VES facility. This study is based at the statistics acquired in $\pi^- Be$ interactions at 27, 36.6 and 41 GeV/c in diffractive reaction $\pi^- N \to (f_1 \pi^-) N$. The $f_1(1285) \to \pi^+\pi^-\pi^0$ decay is observed. The ratio of decay probabilities $BR(f_1(1285) \to \pi^+\pi^-\pi^0)$ to $BR(f_1(1285) \to \eta \pi^+\pi^-) \cdot BR(\eta \to \gamma\gamma)$ is $\sim\:1.4$.Comment: 10 pages, 8 figures, presented at XII Conference on Hadron Spectroscop

Про підвищення ефективності роботи нагнітальних станцій

Розглянуто питання, пов’язані з деякими способами підвищення ефективності роботи нагнітальних станцій при нерівномірному їх навантаженні. Показані приклади добового і річного навантаження нагнітальних станцій, розглянуто характеристики графіків навантажень станції і споживання електроенергії: коефіцієнт заповнення (щільності) графіка навантажень або споживання, коефіцієнт використання максимуму навантаження, коефіцієнт нерівномірності графіка навантаження, що залежать від складу і режиму роботи споживачів продукції нагнітальних станцій. Для оптимального розподілу навантажень при паралельному і послідовному включенні нагнітачів агрегати великої потужності повинні працювати з максимальним ККД, а регулювання подачі (пікових навантажень) при паралельному включенні і регулювання напору при послідовному доцільно здійснювати насосами малої потужності з менш значущим ККД. Для визначення оптимальної частки пікових установок для покриття пікових навантажень нагнітальних станцій використана математична модель на основі співвідношення Россандера. Економічним критерієм, що визначає доцільність введення того чи іншого типу пікових установок і їх питому вагу на станції, є мінімум приведених витрат по станції в цілому. На основі аналізу цього рівняння розглянуто варіант розподілу навантаження між двома типами установок: піковими і іншими установками станції з урахуванням змінної частини наведених витрат по станції, що враховують середньорічну питому витрату електроенергії і її розрахункову вартість, величину і питомі капіталовкладення в установки і їх ефективність, амортизаційні відрахування по установкам та ін. Введення пікових «потужностей» дозволяє підвищити коефіцієнт навантаження станції, при цьому коефіцієнт заповнення графіка навантаження збільшується, що призводить до зниження питомої витрати електроенергії. Показано суттєвий вплив зазначених характеристик графіків навантаження на ефективність роботи нагнітальних станці

An observation of the f0(1710)f_0(1710) meson in the ωϕ\omega\phi system in the Pion-BeBe Interaction at Momentum of 29 GeV

The charge-exchange reaction $\pi^-p \rightarrow n\,\omega(783)\phi(1020)$, $\omega \rightarrow \pi^+\pi^-\pi^0$, $\phi \rightarrow K^+K^-$ is studied with the upgraded VES facility (U-70, Protvino) in the interaction of a 29 GeV pion beam with a beryllium target. The distribution over the invariant mass of the system $M_{\omega\phi}$ shows a near-threshold signal. A partial wave analysis reveals that the scalar state ($J^{PC}=0^{++}$) dominates in this mass region. The observed signal can be described with a contribution of the known resonance $f_0(1710)$. Using OPE approximation for the reaction $\pi^-p \rightarrow n\, f_0(1710)$ the product of branching fractions is found to be: $Br(f_0(1710)\rightarrow \pi\pi)\cdot Br(f_0(1710)\rightarrow \omega\phi) = (4.8 \pm 1.2) \cdot 10^{-3}$

Different-sized porosity and thermal conductivity of oxide layers formed by plasma-electrolytic oxidation on the AlSi12Mg silumin

Oxide layers formed by plasma-electrolytic oxidation (PEO) are characterized by a sufficiently high porosity, which influences almost the whole complex of service characteristics. However, the known data on the integral porosity of PEO-produced layers are rather contradictory, and the pore size distribution in these layers remains understudied. Pore size distribution in the range of 10 nm to 10 µm (pore geometry was approximated by a spherical shape) was obtained by using analysis of scanning electron microscopy (SEM) images in a wide range of magnifications. Lognormal distribution function fits the shape of pore size distribution sufficiently well. Such distribution indicates the nature of pore formation, which can be related to the thermally activated process of gas emission from a liquid melt, the volume and average temperature of which, in turn, depend on the micro-arc discharge energy. The results of the oxide layer phase composition and crystallites sizes by the X-ray crystallography were described in the present paper. The amorphous component phase composition was estimated by the comparing of the of X-ray spectral microanalysis and X-ray crystallography methods. The thermal conductivity of the intact oxide layer and the polished layer (after the removal of its highly-porous outer part) was evaluated by using of the steady-state method and the laser flash method. The porosity values calculated based on the analysis of SEM-images, and the results of determining the phase composition, including amorphous phases, allowed evaluating the oxide layer thermal conductivity with use of four known analytical models. The results of calculating the thermal conductivity using the Loeb model demonstrate the good convergence with the experimental results obtained in this paper. Modeling results the size of crystallites effect on the oxide layer thermal conductivity significantly less than the porosity and amorphous phase

Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal

Hunt for new phenomena using large jet multiplicities and missing transverse momentum with ATLAS in 4.7 fb−1 of s√=7TeV proton-proton collisions

Results are presented of a search for new particles decaying to large numbers of jets in association with missing transverse momentum, using 4.7 fb−1 of pp collision data at s√=7TeV collected by the ATLAS experiment at the Large Hadron Collider in 2011. The event selection requires missing transverse momentum, no isolated electrons or muons, and from ≥6 to ≥9 jets. No evidence is found for physics beyond the Standard Model. The results are interpreted in the context of a MSUGRA/CMSSM supersymmetric model, where, for large universal scalar mass m 0, gluino masses smaller than 840 GeV are excluded at the 95% confidence level, extending previously published limits. Within a simplified model containing only a gluino octet and a neutralino, gluino masses smaller than 870 GeV are similarly excluded for neutralino masses below 100 GeV

Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson

Standalone vertex finding in the ATLAS muon spectrometer

A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

Measurement of the top quark pair cross section with ATLAS in pp collisions at √s=7 TeV using final states with an electron or a muon and a hadronically decaying τ lepton

A measurement of the cross section of top quark pair production in proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 7 TeV is reported. The data sample used corresponds to an integrated luminosity of 2.05 fb -1. Events with an isolated electron or muon and a τ lepton decaying hadronically are used. In addition, a large missing transverse momentum and two or more energetic jets are required. At least one of the jets must be identified as originating from a b quark. The measured cross section, σtt-=186±13(stat.)±20(syst.)±7(lumi.) pb, is in good agreement with the Standard Model prediction