National Institute Of Materials Physics - Romania

CMS is a general purpose experiment, designed to study the physics of pp collisions at 14 TeV at the Large Hadron Collider ( LHC). It currently involves more than 2000 physicists from more than 150 institutes and 37 countries. The LHC will provide extraordinary opportunities for particle physics based on its unprecedented collision energy and luminosity when it begins operation in 2007. The principal aim of this report is to present the strategy of CMS to explore the rich physics programme offered by the LHC. This volume demonstrates the physics capability of the CMS experiment. The prime goals of CMS are to explore physics at the TeV scale and to study the mechanism of electroweak symmetry breaking - through the discovery of the Higgs particle or otherwise. To carry out this task, CMS must be prepared to search for new particles, such as the Higgs boson or supersymmetric partners of the Standard Model particles, from the start- up of the LHC since new physics at the TeV scale may manifest itself with modest data samples of the order of a few fb(-1) or less. The analysis tools that have been developed are applied to study in great detail and with all the methodology of performing an analysis on CMS data specific benchmark processes upon which to gauge the performance of CMS. These processes cover several Higgs boson decay channels, the production and decay of new particles such as Z\' and supersymmetric particles, B-s production and processes in heavy ion collisions. The simulation of these benchmark processes includes subtle effects such as possible detector miscalibration and misalignment. Besides these benchmark processes, the physics reach of CMS is studied for a large number of signatures arising in the Standard Model and also in theories beyond the Standard Model for integrated luminosities ranging from 1 fb(-1) to 30 fb(-1). The Standard Model processes include QCD, B-physics, diffraction, detailed studies of the top quark properties, and electroweak physics topics such as the W and Z(0) boson properties. The production and decay of the Higgs particle is studied for many observable decays, and the precision with which the Higgs boson properties can be derived is determined. About ten different supersymmetry benchmark points are analysed using full simulation. The CMS discovery reach is evaluated in the SUSY parameter space covering a large variety of decay signatures. Furthermore, the discovery reach for a plethora of alternative models for new physics is explored, notably extra dimensions, new vector boson high mass states, little Higgs models, technicolour and others. Methods to discriminate between models have been investigated. This report is organized as follows. Chapter 1, the Introduction, describes the context of this document. Chapters 2-6 describe examples of full analyses, with photons, electrons, muons, jets, missing E-T, B-mesons and tau\'s, and for quarkonia in heavy ion collisions. Chapters 7-15 describe the physics reach for Standard Model processes, Higgs discovery and searches for new physics beyond the Standard Model.

TiO2 thin films prepared by sol-gel method and by RF magnetron sputtering deposited on p-Si(111), n-GaAs(100), and glass have been investigated by XRD, XPS and AFM techniques. The characteristics of the film: colour, adherence and composition are presented in the case of thermal treatments (500 degrees C and 800 degrees C) for sol-gel deposited films as well as for RF sputtering. The TiO2 plasma deposited film is uniform, homogeneous and stoichiometric.

Thin films in the SiO2-P2O5 system are intensely studied due to their applications in microelectronics, sensing, nanophotonics, optoelectronics and as ionic conductors. Sol-gel is the most used method for preparation of such films. Previous studies established the very low reactivity of the phosphorous alkoxides and the high tendency of the phosphorous oxide to volatilise at thermal treatment. In order to identify the most appropriate precursor for obtaining layers with desired composition and properties a systematic study of the sol-gel film preparation using different phosphorous precursors was carried out. The films were deposited on ITO/SiO2 coated glass substrates at room temperature. To check the influence of the type of precursors on the layers thermal stability and properties a post deposition annealing was performed at temperatures of 150 and 200 degrees C. The film characterization was carried out using various techniques as Spectroscopic Ellipsometry (SE), X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR).

For the fabrication of the rectifying contact, respectively the Schottky diode structure on semi-insulating GaAs (100) oriented, Cr-doped, with a resistivity of rho similar to 10(6) - 10(7) Omega cm we have used Au-Ti contact. The Ti contact was deposited on a plasma etched GaAs surface in high vacuum (10(-8) torr), Au was deposited in medium vacuum (10(-6) torr) and the Au-Ti/GaAs interface was formed by a rapid thermal annealing procedure at T = 320 - 360 degrees C in low vacuum (10(-1) torr). The representative I-V characteristics in dark and under illumination at different power levels are presented. It is worth to mention that we estimate a barrier height of Phi(B) similar to 0.84 V (in the frame of thermionic emission model). The spectral response at two operating points and at different temperatures is presented. The signal has a maximum in the Delta lambda range (850-950) nm, which corresponds to the generation of photo-carriers due to a band-to-band direct transition. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

We intend to prepare periodic multilayered structures for photonic applications. With this goal we have performed a study of some characteristics of SiO (x) -P2O5 films deposited by the sol-gel method on glass and ITO (InSnO (x) )-coated glass. The as prepared films were annealed to different temperatures (150 and 200 degrees C). The chemical composition of the samples was determined by X-ray Photoelectron Spectroscopy (XPS). The XPS results revealed the presence of P in the as-deposited films. The structural an optical properties were examined by Fourier Transform Infrared Spectroscopy (FTIR), Spectroellipsometry (SE) and UV Transmission Spectroscopy. IR spectra of the deposited films attest the interaction of an amorphous SiO2 with the H3PO4 used as a P-precursor. Refractive indices for individual SiO (x) -P2O5 determined from SE measurements show a densification of the layer structure with the increasing temperature in the thermal treatment. The UV transmission spectra revealed a lower transmission for the sol-gel SiO (x) -P2O5 films as compared to ITO/glass substrate. AFM images proved the densification of the films with annealing in agreement with the ellipsometric results.

Titanium dioxide thin films prepared by sol-gel method and deposited on p-Si (111), n-GaAs (100) and glass have been investigated by Raman spectrometry and photoluminescence analysis. The films were annealed in the temperature range (500-800)degrees C in air. Raman scattering studies reveal the presence of Raman active modes in the calcinated TiO2 films related to anatase phase of titania. The photo luminescence spectrum presents prominent red shifted peaks (e.g. at 400 nm for TiO2/glass), where the maximum is related to the presence in titania films of defect levels corresponding to oxygen vacancies.

X-Ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES) have been used to investigate the elemental composition, chemical and electronic state of elements that exist within the Herastrau Lake (Bucharest, Romania) sediments. XPS spectra were obtained by irradiating the sediment samples with an Al source of X-rays (1486.6 eV). A very broad peak at 165-190 eV corresponds to sulfur oxides, sulfate and sulfite ions and sulfur hexafluoride. The measurements indicate metal oxides: (Al2O3, Fe2O3) at 528-531 eV, SiO2 at 533 eV, phosphates, nitrates at 531-533 eV, silicates at 532-533 eV, CaO, CaCO3 and CaS at 346-347 eV, CaSo(4) at 348 eV, Ca(NO3)(2) at 349 eV and slight traces of NH3. A very intense peak at 784 eV also appears due to CoSO4. The analysis of Electron Spin Resonance (ESR) spectra revealed an additional free radical peak in the center of Mn2+ sextet, at a g = 2.0038, attributed to SO3- species as well a very intense and broad signal due to Fe3+ ions.

Phosphosilicate films with 90%SiO2-10%P2O5 molar composition, derived from tetraethoxysilane as SiO2 precursor and triethylphosphate, triethylphosphite or phosphoric acid as P2O5 precursors were prepared using the sol-gel method. The films were deposited on glass and ITO coated glass supports. The influence of the type of P2O5 precursor, type of substrate and of the thermal treatment (200, 300 and 500 degrees C) on their structure and properties was studied. By spectroellipsometric and XPS measurements the high vaporization of the phosphorous during the densification of the films by thermal treatment was noticed when alkoxide were used, underlying that the mentioned precursors are not recommended for thin phosphosilicate films preparation. The phosphoric acid that forms chemical bond with silica network during the sol-gel process lead to better incorporation of P in the silica network as compared to the P-alkoxides.

Results are reported on the characterization of 200-250 nm thick TiO(x) transparent films grown at temperatures of 150 degrees C and 500 degrees C by reactive pulsed-laser ablation of a metallic Ti target under 0.13-13.3 Pa oxygen atmosphere. Film structure and composition were investigated by X-ray diffraction and X-ray photoelectron spectroscopy. The samples deposited at 150 degrees C reveal a mixture of amorphous TiO(2) and Ti(2)O(3), irrespective of oxygen pressure. The O:Ti atomic ratio fluctuates in their surface around 1.83 for oxygen pressure ranging between 0.13 Pa and 2.66 Pa. The samples deposited at 500 degrees C feature different characteristics, as a function of oxygen pressure: (a) below 2.66 Pa of O(2) the films contain a mixture of significant amount of anatase and rutile TiO(2) phases, along with titanium suboxides; (b) above this threshold, the rutile phase vanishes, the anatase TiO(2) phase remaining dominant along with small amounts of nanocrystalline suboxides. The size of the anatase nanocrystallites decreases with the increase of oxygen pressures. The samples deposited at 500 degrees C feature a slight improvement of surface stoichiometry, from roughly TiO(1.8) to TiO(1.9). The films deposited at high substrate temperature and oxygen pressure are highly hydrophilic. (c) 2006 Elsevier B.V. All rights reserved.

Thin layers of Fe are deposited at 100 degrees C on GaAs(1 0 0) and InAs(1 0 0) substrates by molecular beam epitaxy. These structures are characterized by photoelectron spectroscopy (PES), in order to derive their chemical composition and interface reactivity, and by X-ray magnetic circular dichroism (XMCD) recorded at room temperature in remanence mode, in order to derive the atomic magnetic moment of Fe. As previously reported, Fe/GaAs(1 0 0) exhibits a strong and complicated interface reactivity, with considerable intermixing of Fe with Ga and As. Unlike the above structure, Fe/InAs(1 0 0) exhibits a much lower interface reactivity, whereas the Fe magnetic moment increase is much more pronounced as function of Fe thickness. The total atomic ferromagnetic moment reaches at room temperature 2.0 Bohr magnetons by about I nm Fe effective thickness, which is almost the Fe bcc bulk value (2.2 Bohr magnetons). The novelty of the present study is a direct comparison of the two interfaces prepared and measured in the same experimental arrangements. (c) 2006 Elsevier B.V. All rights reserved.