Measurement of d sigma/dM and forward-backward charge asymmetry for high-mass Drell-Yan e(+)e(-) pairs from pp macro collisions at square root of s = 1.8 TeV

We report on a measurement of the mass dependence of the forward-backward charge asymmetry, A(FB), and production cross section d sigma/dM for e(+)e(-) pairs with mass M(ee)>40 GeV/c(2). The data sample consists of 108 pb(-1) of pp macro collisions at square root of s = 1.8 TeV taken by the Collider Detector at Fermilab during 1992-1995. The measured asymmetry and d sigma/dM are compared with the predictions of the standard model and a model with an extra Z' gauge boson.     

Catalytic activation of nucleophile precursors with metal acetates in alcohol media and applications to enantioselective Michael addition reactions

Nickel(II) acetate tetrahydrate works as catalyst to activate nucleophile precursors in Michael addition reactions. Use of alcohol media is essential for the high catalytic activation of nucleophile precursors. Catalytic enantioselective reactions using a chiral nickel(II) acetate tetrahydrate between dimedone and α,β-unsaturated amide acceptors provide a useful synthetic access to enantiomers of enol lactones through the carbon-carbon bond formation.     

Study of buried Si(1 1 1)-5 × 2-Au by surface X-ray diffraction

The structure of buried Si(1 1 1)-5 × 2-Au capped with amorphous Si was investigated using surface X-ray diffraction. It was found that the 5 × 2 structural periodicity is kept under the amorphous Si from the in-plane measurement. Furthermore, the intensity variation along the fractional-order rod indicates that Au atoms are located almost on the same plane.     

Interfacial effects on thermoelectric functions

We investigated the effects of added oxide to FeSi₂ on thermoelectric properties in order to improve the figure of merit. The oxide was not suggested to chemically react with the mother material (FeSi₂), where the oxide materials existed in the grain boundaries. The oxide addition played a role to reduce thermal conductivity and possessed electrical resistivity as well as non oxide-added FeSi₂. Hereafter, the appropriate added amount of Yb₂O₃ showed the largest effect on the figure of merit among other oxides.     

Side chain liquid crystal poly(fumarate)s bearing tolane‐based mesogens

Cyanotolane or fluorotolane mesogens were for the first time introduced into the fumarate monomer under basic conditions. All fumarate monomers undergo radical polymerization in benzene in the presence of dimethyl 2,2′‐azobis(isobutyrate) as an initiator at 60 °C, affording the corresponding poly(fumarate)s with a molecular weight (M_n) of ～ 10⁴ and an exceptionally narrow polydispersity. The phase behaviors of the fumarate monomers and the correspoding poly(fumarate)s were comprehensively investigated by differential scanning calorimetry (DSC), polarized optical microscopy (POM), and X‐ray diffraction (XRD) analysis. For the fumarate monomers, fluorotolane derivatives were prone to form higher‐order liquid crystal phases such as a smectic phase, while cyanotolane derivatives tended to show a wide mesophase temperature range, depending on the alkyl chain spacer length. Very surprisingly, these features dramatically weakened when they were polymerized. The mesophase temperature ranges became narrow and completely disappeared for the poly(fumarate)s with a shorter alkyl chain spacer. A nematic phase representing lower‐order arrangements became a predominant liquid crystal phase for the poly(fumarate) carrying cyanotolane mesogens. Only the poly(fumarate) carrying fluorotolane mesogens with a longer alkyl chain spacer displayed the characteristic XRD patterns of the smectic B phase. The transient photocurrent measurements of the fumarate monomer with cyanotolane mesogens displayed a hole mobility of the order of 10^?4–10^?5 cm² V^?1 s^?1 at room temperature. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5101–5114, 2008     

Search for a standard model Higgs boson in the H→ZZ→ℓ(+)ℓ(-)νν decay channel with the ATLAS detector

A search for a heavy standard model Higgs boson decaying via H→ZZ→→?(+)?(-)νν, where ?=e, μ, is presented. It is based on proton-proton collision data at √s=7 TeV, collected by the ATLAS experiment at the LHC in the first half of 2011 and corresponding to an integrated luminosity of 1.04 fb(-1). The data are compared to the expected standard model backgrounds. The data and the background expectations are found to be in agreement and upper limits are placed on the Higgs boson production cross section over the entire mass window considered; in particular, the production of a standard model Higgs boson is excluded in the region 340相似文献   

First observation of the point spread function of optical transition radiation

We represent the first experimental observation of the point spread function (PSF) of optical transition radiation (OTR) performed at KEK-Accelerator Test Facility extraction line. We have demonstrated that the PSF vertical polarization component has a central minimum with a two lobe distribution. However, the distribution width varied significantly with wavelength. We assume that we observed a severe effect from spherical or chromatic aberrations which are not taken into account in any existing theoretical model. We believe that the result of this work will encourage theoreticians to continue developing the theory as it is important for various transition radiation applications. Nonuniform distribution of the OTR PSF creates an opportunity for developing a submicrometer transverse beam size monitor.     

Phase-shifting mask design for interference exposure of chirp blazed grating

An interference exposure system using a phase-shifting mask was proposed for generating periodic sawtooth optical intensity profile with chirp in period. Multiple space-harmonic waves are launched from the mask by diffraction, and the sawtooth optical intensity is formed by interference based on Fourier synthesis after propagation through an air gap. The design concept merely utilizing positive diffraction-order harmonics with tilt illumination of an exposure light and a design algorithm based on time-reversed configuration for calculating required phase shift amount were proposed and discussed. A phase-shifting mask for a blazed grating of very high chirp rate was designed to demonstrate its potential and feasibility. The grating period changes from 2.2 to 3.1 μm gradually within 0.3 mm length. Sawtooth-like optical intensity profile was confirmed by theoretical simulation as well as preliminary experimental results.     

Evaluations of vertical resolution of conductive polymer three-dimensional microstructures photofabricated in transparent polymer sheet

Conductive polymer three-dimensional microstructures were photofabricated utilizing the two-photon absorption of a sensitizer dye. The resulting three-dimensional structures were excised from the transparent polymer sheet using a micro-manipulator. The processing precisions for the vertical direction of the conductive polymer three-dimensional microstructure obtained in the transparent polymer sheet were evaluated in the present study. As a result, for the configurations of the obtained polypyrrole line deposition, the line height/line width ratios were around 5: 1; this ratio is higher than that of other UV resin works (h: w 2:4–3: 1) and the cross section distortion is not negligible for maintaining the higher reproducibility of the photofabrication.     

Ab initio molecular orbital study on three feasible mechanisms for substitution of the vinylic carbon in F2C=C(OMs)BMe3−

A substitution on 2,2-difluorovinylic carbon was investigated by using ab initio molecular orbital calculations. Three feasible mechanisms, which are the S_N1-like, the S_N2-type and the addition-elimination mechanisms, were ex- amined for a model borate, 2,2-difluoro-1-mesyloxyvinyl(trimethyl)borate. Four TSs were obtained depending on the position of Li⁺ around the vinylborate although activation energies in the gas phase are rather high (ca. 30–40 kcal mol⁻¹) in comparison with that expected from the experimental conditions. It was confirmed at the SCRF-IPCM calculations that the solvent effect reduces the acti- vation energy of one S_N2-type mechanism very much (4. l kcal mol⁻¹ at the B3LYP/6-31+G^*//RHF/6-31+G^/s* level of theory) while those for the other mechanisms do not change very much. Therefore, the S_N2-type mechanism is applicable to the substitution reaction observed for the vinylborate.