Development of the PHENIX silicon pixel detector

The PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) is being upgraded with a novel four-layer silicon vertex tracker. The detector will enhance the physics capabilities of PHENIX in the future phase of the heavy-ion and the polarized proton-proton programs at RHIC. The silicon vertex tracker will allow the direct measurement of heavy quark production by identifying displaced decay vertices, and will reconstruct jets with nearly full azimuthal coverage over |η| < 1.2. We are developing a novel Silicon Pixel Detector for the inner two barrel layers of the silicon vertex tracker. In this paper, the status of the development is reported. for the PHENIX collaboration Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”, Budapest, Hungary, 4–9 August 2005.     

Beam test performance of prototype assemblies for the ALICE Silicon Pixel Detector

The silicon pixel detector (SPD) comprises the two innermost layers of the inner tracking system oft he ALICE experiment at LHC. Prototype SPD assemblies have been tested in high-energy proton and pion beams at the CERN SPS. The method used for data analysis and the most relevant results in relation to detector performance are presented. Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”, Budapest, Hungary, 4–9 August 2005. On behalf of the Silicon Pixel Detector project in the ALICE Collaboration     

Silicon-tungsten calorimeter for the forward direction in the PHENIX experiment at RHIC

The PHENIX detector at RHIC has been designed to study hadronic and leptonic signatures of the Quark Gluon Plasma in heavy ion collisions and spin dependent structure functions in polarized proton collisions. The baseline detector measures muons in two muon spectrometers located forward and backward of mid-rapidity, and measures hadrons, electrons, and photons in two central spectrometer arms, each of which covers 90. in azimuth and 0.35 units of rapidity. Further progress requires extending rapidity coverage for hadronic and electromagnetic signatures by upgrading the functionality of the PHENIX muon spectrometers to include photon and jet measurement capabilities. Tungsten calorimeters with silicon pixel readout and fine transverse and longitudinal segmentation are proposed to attain this goal. The use of such a design provides the highest density and finest granularity possible in a calorimeter. for the PHENIX Forward Calorimeter Collaboration Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”, Budapest, Hungary, 4–9 August 2005.     

The PHENIX forward spectrometer upgrade

The forward spectrometer upgrade of the PHENIX detector aims to add capabilities at forward rapidities to: probe nucleon structure through W production and promptphotons in polarized p + p, study nucleon structure in nuclei at high parton densities in p + A collisions through the measurement of γ and π⁰ in the forward region, greatly extend the acceptance for high p _T γ-jet measurements (jet tomography) in A + A, and increase our capabilities to measure the production quarkonium states by giving sensitivity to the χ _c through the J/ψ + γ channel. for the PHENIX Forward Upgrade Collaboration Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”, Budapest, Hungary, 4–9 August 2005.     

The top-quark decay vertex in standard model extensions

New physics interactions can affect the strength and structure of the tbW vertex. We investigate the magnitudes and phases of “anomalous” contributions to this vertex in a two-Higgs doublet and the minimal supersymmetric extension of the standard model, and in a top-color assisted technicolor (TC2) model. While the magnitudes of the anomalous couplings remain below 1 percent in the first two models, TC2 interactions can reduce the left-chiral coupling f _L by several percent.     

A high-performance silicon tracker for the Compressed Baryonic Matter experiment at FAIR

The Compressed Baryonic Matter (CBM) experiment is a fixed-target heavy-ion experiment planned at GSI's future international Facility for Antiproton and Ion Research (FAIR). CBM will study strongly interacting matter at high baryon densities where the QCD phase diagram is poorly known. The experiment applies a detector concept new to heavy-ion physics: All charged particles as well as secondary vertices from heavy-flavor decays are exclusively reconstructed in a high-performance silicon tracking system. It will be installed in a magnetic dipole field between the target and further detection systems for particle identification and calorimetry. High track densities and high collision rates require the application of most advanced silicon detectors. The technological challenges include high position resolution in thinnest possible pixel and microstrip sensors, combined with extreme radiation hardness, fast self-triggered readout and ultra low-mass mechanical supports. The article outlines the physics and detector concept of CBM and discusses the performance requirements of the silicon tracker and the beginning R&D. for the CBM collaboration Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”, Budapest, Hungary, 4–9 August 2005.     

The laser calibration system of the ALICE time projection chamber

A Large Ion Collider Experiment (ALICE) is the only experiment at the Large Hadron Collider (LHC) dedicated to the study of heavy ion collisions. The Time Projection Chamber (TPC) is the main tracking detector covering the pseudo rapidity range |η| < 0.9. It is designed for a maximum multiplicity dN/dy = 8000. The aim of the laser system is to simulate ionizing tracks at predifined positions throughout the drift volume in order to monitor the TPC response to a known source. In particular, the alignment of the read-out chambers will be performed, and variations of the drift velocity due to drift field imperfections can be measured and used as calibration data in the physics data analysis. In this paper we present the design of the pulsed UV laser and optical system, together with the control and monitoring systems. for the ALICE Collaboration Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”, Budapest, Hungary, 4–9 August 2005.     

Quantum de Sitter algebra and some possible applications in cosmology

I summarize results recently obtained in collaboration with Amelino-Camelia, Bruno and Mandanici (preprint University of Rome “La Sapienza”, August, 2005) that concern an analysis of the path of a massless particle in a q-de Sitter space-time and an approximation scheme suitable for the corresponding analysis in a quantum FRW Universe. On the basis of some arguments in the quantum-gravity literature, the q deformation parameter is assumed to depend on both the Planck scale and the curvature, leading to results that are significantly different from those of other studies of Planck-scale effects in cosmology, where the possibility of an interplay between curvature and Planck scale was ignored. Presented at the International Colloquium “Integrable Systems and Quantum Symmetries”, Prague, 16–18 June 2005.     

A representation theorem of set algebras

In this paper we present a representation theorem in set algebras. As an application we describe the structure of σ-algebra of sets generated by an algebra of sets. Presented at the International Colloquium “Integrable Systems and Quantum Symmetries”, Prague, 16–18 June 2005.     

Lorentz gas interacting with an inhomogeneous thermostat

The equilibrium distribution of a Lorentz gas (“electrons”) interacting with an inhomogenous thermostat (“atoms”) is examined with consideration of 1) the concept of volumes available and forbidden for the gas particles and 2) the solution of the kinetic equation. Analytical calculations for “electrons” and “atoms” repelling each other with the force ≈r⁻⁵ (where r is the distance between the particles) have shown that the coordinate- and velocity-dependent variables in the distribution function cannot be separated. In particular, this leads to the dependence of the average kinetic energy per “electron” on the coordinate: it is higher in the region with higher density of the “atoms”. It is assumed that the Gibbs distribution does not describe the properties of the system under consideration, because in this case the interaction between the system and thermostat cannot be considered small. Scientific-Research Physical-Technical Institute at N. I. Lobachevskii Nizhnii Novgorod State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 38–43, June, 1999.     

An explicitly solvable model of the spontaneous <Emphasis Type="Italic">PT</Emphasis>-symmetry breaking

We contemplate the pair of the purely imaginary delta-function potentials on a finite interval with Dirichlet boundary conditions. The two parameter model exhibits nicely the expected quantitative features of the unavoided level crossing and of a “phase-transition” complexification of the energies. Combining analytic and numerical techniques we investigate strength- and position-dependence of spectrum. Presented at the 3rd International Workshop “Pseudo-Hermitian Hamiltonians in Quantum Physics”, Istanbul, Turkey, June 20–22, 2005.     

Measuring beauty production in Pb-Pb collisions at the LHC via single electrons in ALICE

We present the expected ALICE performance for the measurement of the p _t-differential cross section of electrons from beauty decays in central Pb-Pb collisions at the LHC. for the ALICE Collaboration Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”, Budapest, Hungary, 4–9 August 2005.     

Nonlocal charges in susy integrable models

We study systematically the general properties of theB-extension of any integrable model and its properties as Hamiltonian structures etc. We clarify the origin of “exotic” changes in such models. We show that in such models there exist at least two sets of non-local conserved charges and that the “exotic” charges are part of this non-local charge hierarchy. Presented at the 9th Colloquium “Quantum Groups and Integrable Systems”, Prague, 22–24 June 2000.     

Lagrangian fractional mechanics — a noncommutative approach

The extension of coordinate-velocity space with noncommutative algebra structure is proposed. For action of fractional mechanics considered on such a space the respective Euler-Lagrange equations are derived via minimum action principle. It appears that equations of motion in the noncommutative framework do not mix left and right derivatives thus being simple to solve at least in the linear case. As an example, two models of oscillator with fractional derivatives are studied. Presented at the International Colloquium “Integrable Systems and Quantum Symmetries”, Prague, 16–18 June 2005.     

A fast muon trigger for the PHENIX forward spectrometer upgrade

The PHENIX forward upgrade adds nosecone calorimeters and level-1 trigger (LVL-1) detectors to the muon forward spectrometers. The muon detector will trigger on high pT muons from W decay and reject background. This will enable study of quark and anti-quark polarizations in the proton. The upgrade will add momentum and timing information to the present muon trigger. Signals from 3 Resistive Plate Chambers (RPCs) will provide momentum and timing information for the LVL-1 trigger. Each RPC carries a plane with coarse structure to establish a space point for timing and one with radial cathode strips for azimuthal resolution. Timing resolution of ≈ 2 ns rejects beam-related backgrounds and tracking from RPCs minimizes muons from hadron decays. RPC information is sent by optical. bers to LVL-1 trigger processors. A discussion of physics measurements possible, layout of the upgrade and details of RPC design and tests are given below. for the PHENIX collaboration Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”, Budapest, Hungary, 4–9 August 2005.     

Features of the melting dynamics of a vortex lattice in a high-T c superconductor in the presence of pinning centers

The phase transition “triangular lattice-vortex liquid” in layered high-T _c superconductors in the presence of pinning centers is studied. A two-dimensional system of vortices simulating the superconducting layers in a high-T _c Shubnikov phase is calculated by the Monte Carlo method. It was found that in the presence of defects the melting of the vortex lattice proceeds in two stages: First, the ideal triangular lattice transforms at low temperature (≃3 K)into islands which are pinned to the pinning centers and rotate around them and then, at a higher temperature (≃8 K for T _c 584 K), the boundaries of the “islands” become smeared and the system transforms into a vortex liquid. As the pinning force increases, the temperatures of both phase transitions shift: The temperature of the point “triangular lattice-rotating lattice” decreases slightly (to ≃2 K)and the temperature of the phase transition “rotating lattice-vortex liquid” increases substantially (≃70 K). Pis’ma Zh. éksp. Teor. Fiz. 66, No. 4, 269–274 (25 August 1997)     

“Elastic” fluctuation-induced effects in smectic wetting films

The Li-Kardar field theory approach is generalized to wetting smectic films and the “elastic” fluctuation-induced interaction is obtained between the external flat bounding surface and distorted IA (isotropic liquid-smectic A) interface acting as an “internal” (bulk) boundary of the wetting smectic film under the assumption that the IA interface is essentially “softer” than the surface smectic layer. This field theory approach allows calculating the fluctuation-induced corrections in Hamiltonians of the so-called “correlated” liquids confined by two surfaces, in the case where one of the bounding surfaces is “rough” and with different types of surface smectic layer anchoring. We obtain that in practice, the account of thermal displacements of the smectic layers in a wetting smectic film reduces to the addition of two contributions to the IA interface Hamiltonian. The first, so-called local contribution describes the long-range thermal “elastic” repulsion of the fluctuating IA interface from the flat bounding surface. The second, so-called nonlocal contribution is connected with the occurrence of an “elastic” fluctuation-induced correction to the stiffness of the IA interface. An analytic expression for this correction is obtained.     

Large piezoelectric effects in charged, heterogeneous fluoropolymer electrets

Large piezoelectric d₃₃ coefficients around 600 pC/N are found in corona-charged non-uniform electrets consisting of elastically “soft” (microporous polytetrafluoroethylene PTFE) and “stiff” (perfluorinated cyclobutene PFCB) polymer layers. The piezoelectric activity of the two-layer fluoropolymer stack exceeds the d₃₃ coefficient of the ferroelectric ceramic lead zirconate titanate (PZT) by more than a factor of two and that of the ferroelectric polymer polyvinylidene fluoride (PVDF) by a factor of 20. Soft piezoelectric materials may become interesting for a large number of sensor and transducer applications, in areas such as security systems, medical diagnostics, and nondestructive testing. Accepted: 9 November 1999 / Published online: 3 December 1999     

Phase diagram of multilayer ferromagnet-layered-antiferromagnet structures

This paper discusses the thickness-roughness phase diagram of a three-layer system consisting of two ferromagnetic layers separated by an antiferromagnetic interlayer. It is shown that the stability region of single-domain ferromagnetic layers is determined by the ratio between the width of the atomic steps that appear at the interfaces of the layers during their growth and the thicknesses of the layers, and also by the values of the interlayer and intralayer exchange interactions. A basis is provided for the phenomenological “magnetic closeness” model proposed by Slonczewski, and an expression is obtained for the constants of this model. Fiz. Tverd. Tela (St. Petersburg) 41, 1240–1247 (July 1999)     

Ettore Majorana’s Course on Theoretical Physics: A Recent Discovery

We analyze in some detail the course that Ettore Majorana gave on theoretical physics at the University of Naples between January and March 1938, just prior to his mysterious disappearance. We discuss, in particular, the recently discovered Moreno Lecture Notes, in which all of Majorana’s lectures are recorded, six of which are not present in those that are preserved in the Domus Galilaeana in Pisa, Italy. Antonino Drago is a retired professor of history of physics at the University of Naples “Federico II.” Salvatore Esposito is a researcher on theoretical physics and history of physics at the University of Naples “Federico II.”