Parameter Symmetry of the Interacting Boson Model

We discuss the symmetry of the parameter space of the interacting boson model (IBM). It is shown that for any set of the IBM Hamiltonian parameters (with the only exception of the U(5) dynamical symmetry limit) one can always find another set that generates the equivalent spectrum. We discuss the origin of the symmetry and its relevance for physical applications.Comment: Minor changes; Revtex, 14 pages with 1 figur

NIR Microscopy Possibilities for the Visualization of Silicon Microelectronic Structure Topology through the Substrate

AbstractExperimental setup based on visible and NIR spectral range microscope with laser port and picosecond laser is developed for silicon integrated circuit (IC) failure analysis. The possibility of visualizing the topology of the submicron technology silicon structures from the back side of the crystal through the substrate is shown. Main features of new setup are demonstrated by some results of backside focused pulsed laser beam initiated latchup effect study. The possibility of the localization of the latchup sensitive areas under focused laser irradiation is shown. NIR light emission accompanying the latchup effect is observed and analyzed. The practical aspects of NIR microscopy for failure analysis under backside laser irradiation are discussed

Master equation for spin-spin correlation functions of the XXZ chain

We derive a new representation for spin-spin correlation functions of the finite XXZ spin-1/2 Heisenberg chain in terms of a single multiple integral, that we call the master equation. Evaluation of this master equation gives rise on the one hand to the previously obtained multiple integral formulas for the spin-spin correlation functions and on the other hand to their expansion in terms of the form factors of the local spin operators. Hence, it provides a direct analytic link between these two representations of the correlation functions and a complete re-summation of the corresponding series. The master equation method also allows one to obtain multiple integral representations for dynamical correlation functions.Comment: 24 page

Role of radial electric field in LH transition triggered by counter-NBI at low plasma Density in the TUMAN-3M tokamak

Threshold power needed to attain H-mode in a tokamak is a critical parameter for designing of future devices and in particular fusion reactor ITER [1]. According to commonly accepted scaling [2] the threshold power Pthr increases with average density ne when the density exceeds some ne min at which Pthr is minimal. An increase in the Pthr towards low density was observed in many experiments [3-6], prevents the transition at lower ne as well. Physics of the threshold power increase at low ne is not well understood. Since the radial electric field Er and Er×B sheared flow play important roles in the LH transition one could expect these quantities effect the low transitions. Toroidal rotation and radial electric field generation during counter-NBI have been studied in [7] and recently reconsidered theoretically in [8]. Thus, motivation for the presented study is to analyze effect of counter-NBI on the LH transition at low density.Гранична потужність Pthr, необхідна для переходу в H-режим, є критичним параметром при проектуванні термоядерних установок, у тому числі реактора ITER [1]. Відповідно до загальноприйнятого скейлинга [2] Pthr збільшується з ростом середньої щільності плазми ne, якщо ne перевершує деяке значення, при якому Pthr мінімальна. Збільшення Pthr при низьких щільностях також спостерігалося в багатьох експериментах [3-6]. Фізика цього явища до кінця не з'ясована. Однак, з огляду на той факт, що радіальне електричне поле Er і Er×B обертання плазми відіграють важливу роль у механізмі LH-переходу, можна очікувати, що ці фактори впливають і на LH-перехід при низьких щільностях. Явища тороїдального обертання плазми і появи Er під час контр-інжекції пучка нейтральних атомів були недавно досліджені як експериментально [7], так і теоретично [8]. Метою роботи, що представляється, є аналіз впливу контр-інжекції на процес LH-переходу при низькій щільності.Пороговая мощность Pthr, необходимая для перехода в H-режим, является критическим параметром при проектировании термоядерных установок, в том числе реактора ITER [1]. В соответствии с общепринятым скейлингом [2] Pthr увеличивается с ростом средней плотности плазмы ne, если ne превосходит некоторое значение, при котором Pthr минимальна. Увеличение Pthr при низких плотностях также наблюдалось во многих экспериментах [3-6]. Физика этого явления до конца не выяснена. Однако, учитывая тот факт, что радиальное электрическое поле Er и Er×B вращение плазмы играют важную роль в механизме LH-перехода, можно ожидать, что эти факторы влияют и на LH-переход при низких плотностях. Явления тороидального вращения плазмы и появления Er во время контр-инжекции пучка нейтральных атомов были недавно исследованы как экспериментально [7], так и теоретически [8]. Целью представляемой работы является анализ влияния контр-инжекции на процесс LH-перехода при низкой плотности

Spin asymmetry A_1^d and the spin-dependent structure function g_1^d of the deuteron at low values of x and Q^2

We present a precise measurement of the deuteron longitudinal spin asymmetry A_1^d and of the deuteron spin-dependent structure function g_1^d at Q^2 < 1 GeV^2 and 4*10^-5 < x < 2.5*10^-2 based on the data collected by the COMPASS experiment at CERN during the years 2002 and 2003. The statistical precision is tenfold better than that of the previous measurement in this region. The measured A_1^d and g_1^d are found to be consistent with zero in the whole range of x.Comment: 17 pages, 10 figure

The COMPASS Experiment at CERN

The COMPASS experiment makes use of the CERN SPS high-intensitymuon and hadron beams for the investigation of the nucleon spin structure and the spectroscopy of hadrons. One or more outgoing particles are detected in coincidence with the incoming muon or hadron. A large polarized target inside a superconducting solenoid is used for the measurements with the muon beam. Outgoing particles are detected by a two-stage, large angle and large momentum range spectrometer. The setup is built using several types of tracking detectors, according to the expected incident rate, required space resolution and the solid angle to be covered. Particle identification is achieved using a RICH counter and both hadron and electromagnetic calorimeters. The setup has been successfully operated from 2002 onwards using a muon beam. Data with a hadron beam were also collected in 2004. This article describes the main features and performances of the spectrometer in 2004; a short summary of the 2006 upgrade is also given.Comment: 84 papes, 74 figure

Gluon polarization in the nucleon from quasi-real photoproduction of high-pT hadron pairs

We present a determination of the gluon polarization Delta G/G in the nucleon, based on the helicity asymmetry of quasi-real photoproduction events, Q^2<1(GeV/c)^2, with a pair of large transverse-momentum hadrons in the final state. The data were obtained by the COMPASS experiment at CERN using a 160 GeV polarized muon beam scattered on a polarized 6-LiD target. The helicity asymmetry for the selected events is = 0.002 +- 0.019(stat.) +- 0.003(syst.). From this value, we obtain in a leading-order QCD analysis Delta G/G=0.024 +- 0.089(stat.) +- 0.057(syst.) at x_g = 0.095 and mu^2 =~ 3 (GeV}/c)^2.Comment: 10 pages, 3 figure

The Deuteron Spin-dependent Structure Function g1d and its First Moment

We present a measurement of the deuteron spin-dependent structure function g1d based on the data collected by the COMPASS experiment at CERN during the years 2002-2004. The data provide an accurate evaluation for Gamma_1^d, the first moment of g1d(x), and for the matrix element of the singlet axial current, a0. The results of QCD fits in the next to leading order (NLO) on all g1 deep inelastic scattering data are also presented. They provide two solutions with the gluon spin distribution function Delta G positive or negative, which describe the data equally well. In both cases, at Q^2 = 3 (GeV/c)^2 the first moment of Delta G is found to be of the order of 0.2 - 0.3 in absolute value.Comment: fits redone using MRST2004 instead of MRSV1998 for G(x), correlation matrix adde