Thermoelectric properties of Pr3Rh4Sn13-type Yb3Co4Ge13 and Yb3Co4Sn13 compounds

Crystallographic data and thermoelectric properties (from 240 K up to 380 K) of Yb3Co4Ge13, Yb3Co4Sn13 compounds and Yb2CeCo4Ge13 and Yb2.3La0.7Co4Ge13 solid solutions are reported. The Seebeck coefficients, electric resistance and thermal conductivity increase monotonically with increasing temperature from 240 to 380 K for all the compounds. The Seebeck coefficient is S = 14 - 27 \mu V//K for Yb3Co4Sn13, and S = -21 -- -12 \mu V/K for Yb3Co4Ge13. The substitution of Yb for cerium or lanthanum in Yb3Co4Ge13 shifts the Seeebeck coefficient to positive values. The Yb3Co4Sn13 has a maximal ZT parameter from available Pr3Rh4Sn13-type compounds. The ZT parameter of Yb3Co4Sn13 compound increases from 0.006 up to 0.017 with increasing temperature from 240 K to 380 K.Comment: 9 pages, pdf, final version, accepted to Journal of Alloys and Compound

The control system for radiation sterilization of health-care products at the accelerator LU-10

The regulatory documents for the technological process of sterilization (DSTU ISO 11 137:2003 and others) set requirements on monitoring, maintaining and archiving the basic parameters of the process. To meet the requirements, an automated control system was created at the LU-10. It includes a PC-controlled beam scanner, technological measuring channels (TMC), and also a set of working standards to calibrate the channels. The CAMAC standard was used as an interface. The software of the complex provides the real-time processing of information on the beam parameters, their control, archiving, and also the information exchange within the local-area technological network. The presence of the Customer Database comprising the characteristics of incoming products makes it possible to optimize the process conditions for the products by the computer simulation method.Нормативные документы на технологический процесс стерилизации (ДСТУ ISO 11 137:2003 и др.) устанавливают требования мониторирования, поддержания и архивирования основных параметров процесса. Для удовлетворения этим требованиям на ЛУ-10 создана автоматизированная система контроля. В ее состав входит управляемый РС сканер пучка, технологические измерительные каналы, а также набор рабочих эталонов для калибровки каналов. В качестве интерфейса использован стандарт КАМАК. Программное обеспечение комплекса дает возможность в режиме реального времени производить обработку информации о параметрах пучка, управлять ими, их архивировать, а также обмениваться информацией в пределах локальной технологической сети. Наличие базы данных «Заказчик» с характеристиками поступающей продукции позволяет оптимизировать режим ее обработки методом компьютерного моделирования.Нормативні документи на технологічний процес стерилізації (ДСТУ ISO 11 137:2003 та інші) установлюють вимоги моніторування, підтримки і архивування основних параметрів процесу. Для задоволення цим вимогам на ЛП-10 створена автоматизована система контролю. У її склад входить керований РС сканер пучка, технологічні вимірювальні канали, а також набір робочих еталонів для калібрування каналів. Як інтерфейс використаний стандарт КАМАК. Програмне забезпечення комплексу дає можливість у режимі реального часу робити обробку інформації про параметри пучка, керувати ними, архивувати їх, а також обмінюватися інформацією в межах локальної технологічної мережі. Наявність бази даних «Замовник» з характеристиками продукції, що надходить, дозволяє оптимізувати режим її обробки методом комп'ютерного моделювання

Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio

Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter

Measurement of the inclusive isolated prompt photon cross-section in pp collisions at sqrt(s)= 7 TeV using 35 pb-1 of ATLAS data

A measurement of the differential cross-section for the inclusive production of isolated prompt photons in pp collisions at a center-of-mass energy sqrt(s) = 7 TeV is presented. The measurement covers the pseudorapidity ranges |eta|<1.37 and 1.52<=|eta|<2.37 in the transverse energy range 45<=E_T<400GeV. The results are based on an integrated luminosity of 35 pb-1, collected with the ATLAS detector at the LHC. The yields of the signal photons are measured using a data-driven technique, based on the observed distribution of the hadronic energy in a narrow cone around the photon candidate and the photon selection criteria. The results are compared with next-to-leading order perturbative QCD calculations and found to be in good agreement over four orders of magnitude in cross-section.Comment: 7 pages plus author list (18 pages total), 2 figures, 4 tables, final version published in Physics Letters

Reducing heterotic M-theory to five dimensional supergravity on a manifold with boundary

This paper constructs the reduction of heterotic $M$-theory in eleven dimensions to a supergravity model on a manifold with boundary in five dimensions using a Calabi-Yau three-fold. New results are presented for the boundary terms in the action and for the boundary conditions on the bulk fields. Some general features of dualisation on a manifold with boundary are used to explain the origin of some topological terms in the action. The effect of gaugino condensation on the fermion boundary conditions leads to a `twist' in the chirality of the gravitino which can provide an uplifting mechanism in the vacuum energy to cancel the cosmological constant after moduli stabilisation.Comment: 16 pages, RevTe

Measurement of D*+/- meson production in jets from pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

This paper reports a measurement of D*+/- meson production in jets from proton-proton collisions at a center-of-mass energy of sqrt(s) = 7 TeV at the CERN Large Hadron Collider. The measurement is based on a data sample recorded with the ATLAS detector with an integrated luminosity of 0.30 pb^-1 for jets with transverse momentum between 25 and 70 GeV in the pseudorapidity range |eta| < 2.5. D*+/- mesons found in jets are fully reconstructed in the decay chain: D*+ -> D0pi+, D0 -> K-pi+, and its charge conjugate. The production rate is found to be N(D*+/-)/N(jet) = 0.025 +/- 0.001(stat.) +/- 0.004(syst.) for D*+/- mesons that carry a fraction z of the jet momentum in the range 0.3 < z < 1. Monte Carlo predictions fail to describe the data at small values of z, and this is most marked at low jet transverse momentum.Comment: 10 pages plus author list (22 pages total), 5 figures, 1 table, matches published version in Physical Review

Search for scalar top quark pair production in natural gauge mediated supersymmetry models with the ATLAS detector in pp collisions at sqrt(s) = 7 TeV

The results of a search for pair production of the lighter scalar partners of top quarks in 2.05 fb-1 of pp collisions at sqrt(s) =7 TeV using the ATLAS experiment at the LHC are reported. Scalar top quarks are searched for in events with two same flavour opposite-sign leptons (electrons or muons) with invariant mass consistent with the Z boson mass, large missing transverse momentum and jets in the final state. At least one of the jets is identified as originating from a b-quark. No excess over Standard Model expectations is found. The results are interpreted in the framework of R-parity conserving, gauge mediated Supersymmetry breaking `natural' scenarios, where the neutralino is the next-to-lightest supersymmetric particle. Scalar top quark masses up to 310 GeV are excluded for the lightest neutralino mass between 115 GeV and 230 GeV at 95% confidence level, reaching an exclusion of the scalar top quark mass of 330 GeV for the lightest neutralino mass of 190 GeV. Scalar top quark masses below 240 GeV are excluded for all values of the lightest neutralino mass above the Z boson mass.Comment: 7 pages plus author list (20 pages total), 4 figures, 1 table, matches published PLB versio

Measurement of the production cross section of prompt j/psi mesons in association with a W (+/-) boson in pp collisions root s=7 TeV with the ATLAS detector

The process pp → W±J/ψ provides a powerful probe of the production mechanism of charmonium in hadronic collisions, and is also sensitive to multiple parton interactions in the colliding protons. Using the 2011 ATLAS dataset of 4.5 fb-1 of p s = 7TeV pp collisions at the LHC, the first observation is made of the production of W± + prompt J/ events in hadronic collisions, using W± → μ and J/ψ → μ+μ-. A yield of 27.4±7.5 -6.5 W± + prompt J/ψ events is observed, with a statistical significance of 5.1. The production rate as a ratio to the inclusive W± boson production rate is measured, and the double parton scattering contribution to the cross section is estimated. Copyright CERN, for the benefit of the ATLAS Collaboration