Cross sections and transverse single-spin asymmetries in forward neutral-pion production from proton collisions at sqrt[s]=200 GeV

Measurements of the production of forward high-energy pi(0) mesons from transversely polarized proton collisions at sqrt[s]=200 GeV are reported. The cross section is generally consistent with next-to-leading order perturbative QCD calculations. The analyzing power is small at x(F) below about 0.3, and becomes positive and large at higher x(F), similar to the trend in data at sqrt[s]< or =20 GeV. The analyzing power is in qualitative agreement with perturbative QCD model expectations. This is the first significant spin result seen for particles produced with p(T)>1 GeV/c at a polarized proton collider.     

Azimuthal anisotropy and correlations at large transverse momenta in p + p and Au + Au collisions at square root sNN=200 GeV

Results on high transverse momentum charged particle emission with respect to the reaction plane are presented for Au + Au collisions at square root s(NN)=200 GeV. Two- and four-particle correlations results are presented as well as a comparison of azimuthal correlations in Au + Au collisions to those in p + p at the same energy. The elliptic anisotropy v(2) is found to reach its maximum at p(t) approximately 3 GeV/c, then decrease slowly and remain significant up to p(t) approximately 7-10 GeV/c. Stronger suppression is found in the back-to-back high-p(t) particle correlations for particles emitted out of plane compared to those emitted in plane. The centrality dependence of v(2) at intermediate p(t) is compared to simple models based on jet quenching.     

Long-range critical wetting: observation of a critical end point

Alkanes deposited on aqueous substrates exhibit two different types of wetting behavior: alternatively to the usual first-order wetting transition, a sequential-wetting scenario of a long-range critical wetting transition preceded by a first-order thin-thick transition may be observed. Here, we present the first successful experimental attempt to locate the transition point between the standard first-order wetting and the long-range critical wetting: a critical end point, observed in a mixture of pentane and hexane which is deposited on an aqueous solution of glucose. Furthermore, we present the first direct measurement of the contact angle in the intermediate wetting state (frustrated-complete wetting) in the sequential-wetting scenario of hexane on brine and compare to theoretical predictions.     

Dependence of hole effective mass on nitrogen concentration in W-type strained InAs(N)/GaSb/InAs(N) quantum well lasers

We have investigated the effects of nitrogen N concentration on the properties of hole subbands and effective mass in dilute-nitride type-II InAsN/GaSb laser diodes on InAs substrate with “W” design. Using a 5-bands k·p model, we obtained interesting numerical results for the heavy-hole (hh) and the light-hole (lh) subbands. The hole effective masses were found to be very sensitive to the nitrogen concentration and to the differences in the Luttinger parameters between the well and the barrier. In addition, the hole effective masses are found to be strongly affected by band-anticrossing (BAC) model.     

Combined EELS, LEED and SR-XPS study of ultra-thin crystalline layers of indium nitride on InP(1 0 0)—Effect of annealing at 450 °C

In this study, InP(1 0 0) surfaces were bombarded by argon ions in ultra high vacuum. Indium metallic droplets were created in well controlled quantities and played the role of precursors for the nitridation process. A glow discharge cell was used to produce a continuous plasma with a majority of N atomic species. X-ray photoelectron spectroscopy (XPS) studies indicated that the nitrogen combined with indium surface atoms to create InN thin films (two monolayers) on an In rich-InP(1 0 0) surface. This process occurred at low temperature: 250 °C. Synchrotron radiation photoemission (SR-XPS) studies of the valence band spectra, LEED and EELS measurements show an evolution of surface species and the effect of a 450 °C annealing of the InN/InP structures. The results reveal that annealing allows the crystallization of the thin InN layers, while the LEED pattern shows a (4 × 1) reconstruction. As a consequence, InN related structures in EELS and valence bands spectra are different before and after the annealing. According to SR-XPS measurements, the Fermi level is found to be pinned at 1.6 eV above the valence band maximum (VBM).     

Partonic Flow and phi-Meson production in Au+Au collisions at sqrt radical sNN = 200 GeV

We present first measurements of the phi-meson elliptic flow (v2(pT)) and high-statistics pT distributions for different centralities from radical sNN=200 GeV Au+Au collisions at RHIC. In minimum bias collisions the v2 of the phi meson is consistent with the trend observed for mesons. The ratio of the yields of the Omega to those of the phi as a function of transverse momentum is consistent with a model based on the recombination of thermal s quarks up to pT approximately 4 GeV/c, but disagrees at higher momenta. The nuclear modification factor (R CP) of phi follows the trend observed in the K S 0 mesons rather than in Lambda baryons, supporting baryon-meson scaling. These data are consistent with phi mesons in central Au+Au collisions being created via coalescence of thermalized s quarks and the formation of a hot and dense matter with partonic collectivity at RHIC.     

Dual-frequency single-axis laser using a lead lanthanum zirconate tantalate (PLZT) birefringent etalon for millimeter wave generation: beyond the standard limit of tunability

We demonstrate the generation of optically carried, broadly tunable, millimeter-wave signals with a dual-frequency single-axis Nd:YAG laser. A frequency difference as high as 127 GHz is reached thanks to an intracavity electro-optically tunable etalon made of lead zirconate tantalate (PLZT) ceramic. We show that the available frequency range is actually limited by the bandwidth of the amplification medium, namely, far beyond the usually accepted free spectral range value in the case of a single-axis laser. Both coarse discrete and fine continuous tunabilities are obtained with the same voltage-controlled device, opening the way to widely tunable low-phase-noise optically carried submillimeter or even terahertz sources.     

The Cut Metric,Random Graphs,and Branching Processes

In this paper we study the component structure of random graphs with independence between the edges. Under mild assumptions, we determine whether there is a giant component, and find its asymptotic size when it exists. We assume that the sequence of matrices of edge probabilities converges to an appropriate limit object (a kernel), but only in a very weak sense, namely in the cut metric. Our results thus generalize previous results on the phase transition in the already very general inhomogeneous random graph model introduced by the present authors in Random Struct. Algorithms 31:3–122 (2007), as well as related results of Bollobás, Borgs, Chayes and Riordan (Ann. Probab. 38:150–183, 2010), all of which involve considerably stronger assumptions. We also prove corresponding results for random hypergraphs; these generalize our results on the phase transition in inhomogeneous random graphs with clustering (Random Struct. Algorithms, 2010, to appear).     

Magnetic calorimeter for registration of small energy release

A scheme of magnetic calorimeter for registration of rare events characterized by small energy release (cosmic rays, WIMPs, solitary X-ray quanta) is proposed. The calorimeter is brought to operation by adiabatic demagnetization, and its magnetic response is measured by a quantum interferometer (SQUID, A. Barone and G. Paterno, Physics and applications of Josephson Effect). Special consideration is given to the specific features of calorimeter operation in the ferromagnetic transition region. The trigger registration of ultrasmall energy release by a ferromagnetic system in the metastable state is described.