PZT thin film growth and chemical composition control on flat and novel three-dimensional micromachined structures for MEMS devices

Piezoelectric micro-electro-mechanical systems (MEMS) are finding an increased interest for applications requiring high frequency operation and high mechanical quality. The aim of this work was to improve piezoelectric MEMS along two main research directions. The first one was devoted to the strongest piezoelectric thin film material so far established, namely to the solid solution system lead zirconate titanate (PZT), whose properties are peaking at the morphotropic phase boundary at 53/47 Zr to Ti ratio. Properties of such films were lagging behind the ones of bulk ceramics. In sol-gel deposited films, one of deteriorating factors was earlier identified in the compositional gradient preventing to hit the 53/47 composition throughout the whole film volume. In this work, this gradient could be lowered by the preparation of a new set of solutions, reducing the Zr concentration fluctuations from ±12 to ±2.5at%. In combination with a new sol-gel PbTiO3(100) seed layer, and an optimized lead excess and heating scheme, the transverse piezoelectric coefficient |e31.f| could be increased from 12 to 17 C/m2 in 2µm {100}-textured PZT thin films deposited on plane 100mm wafers. In parallel the dielectric constant increased from 1200 to 1500 with a decreasing loss tangent. It could be shown that the dielectric loss must be entirely due to domain wall motions. The second research direction was devoted to the introduction of new piezoelectric shapes by means of deposition into cavities. A free calotte membrane, consisting of a sputtered PZT thin film and its electrodes, has been successfully developed and fabricated as demonstrator of a novel three-dimensional transducer. Calotte profile holes in silicon were prepared by wet etching, and were used as micromould for the PZT membrane. The quasi-static vibration amplitude was measured by means of atomic force microscopy (AFM) yielding a responsivity of 3.5 nm/V, i.e. about 20 to 50 times the d31 value. The second device was a piezoelectric PZT coated active AFM cantilever. A PZT layer was sputter deposited on patterned (111) platinum bottom electrodes into deep cavities (>300µm) prepared by anisotropic wet chemical etching. The photolithography was made possible using spray coating techniques and correcting masks for aberration errors. The study of the basic properties of such a structure has shown promising results. The maximum deflection at the end of the beam was measured as 5.3 nm/V in quasi-static operation. The so derived e31,f value in the cavity corresponded well to the value obtained on flat wafers. Micro-structural analysis showed that PZT grains grow always perpendicular to the local surface inclination, showing no effect of directional sputter flux. The texturing scheme worked as well on inclined surfaces, i.e. the Pt(111) planes and the PZT {100} planes always stay parallel to the local surface

Piezoelectric micromachined ultrasonic transducers with thick PZT sol gel films

The fabricated micro machined ultrasonic transducers (pMUT) was based on piezoelectric laminated plates operating at flexural modes. The fabricated bimorph pMUT transducers were composed of 5-layers. A 4μm thick lead zirconate titanate (PZT) thin film deposited by a sol-gel method was used. The piezoelectric layer exhibited a capacitance corresponding to a permitivity of ɛ r = 1,200. The electromechanical coupling coefficient (k 2) and quality factor (Q) were measured as k 2 = 4.4% and Q = 145 in air for a low frequency transducer (240kHz). The effect of DC bias voltage on frequency and k 2 has been studied. The 16.9MHz transducer yielded values of Q = 25 in air and k 2 = 3

Production of Drell--Yan lepton pairs in hadron collisions: transverse-momentum resummation at next-to-next-to-leading logarithmic accuracy

We consider the transverse-momentum (q_T) distribution of Drell--Yan lepton pairs produced in hadron collisions. At small values of q_T, we resum the logarithmically-enhanced perturbative QCD contributions up to next-to-next-to-leading logarithmic accuracy. At intermediate and large values of q_T, we consistently combine resummation with the known next-to-leading order perturbative result. All perturbative terms up to order alpha_S^2 are included in our computation which, after integration over q_T, reproduces the known next-to-next-to-leading order result for the Drell--Yan total cross section. We show and discuss the reduction in the scale dependence of the results with respect to lower-order calculations, estimating the corresponding perturbative uncertainty. We present a preliminary comparison with Tevatron Run II data.Comment: Additional details shown in Fig.3. Note added on the quantitative effect of the coefficient A^{(3)

Transverse-momentum resummation: a perturbative study of Z production at the Tevatron

We consider transverse-momentum (q_T) resummation for Drell--Yan lepton pair production in hadron collisions. At small values of q_T, the logarithmically-enhanced QCD contributions are resummed up to next-to-leading logarithmic accuracy. At intermediate and large values of q_T, resummation is consistently combined with the fixed-order perturbative result. We present numerical results for e^+e^- pairs from the decay of Z bosons produced at Tevatron energies. We perform a detailed study of the scale dependence of the results to estimate the corresponding perturbative uncertainty. We comment on the comparison with the available Tevatron data.Comment: 24 pages, 12 ps figures, added comments and references; results unchange

Precision studies of observables in pp → W → lνl and pp → γ , Z → l+l− processes at the LHC

This report was prepared in the context of the LPCC Electroweak Precision Measurements at the LHC WG (https://lpcc.web.cern.ch/lpcc/index.php?page=electroweak_wg) and summarizes the activity of a subgroup dedicated to the systematic comparison of public Monte Carlo codes, which describe the Drell–Yan processes at hadron colliders, in particular at the CERN Large Hadron Collider (LHC). This work represents an important step towards the definition of an accurate simulation framework necessary for very high-precision measurements of electroweak (EW) observables such as the W boson mass and the weak mixing angle. All the codes considered in this report share at least next-to-leading-order (NLO) accuracy in the prediction of the total cross sections in an expansion either in the strong or in the EW coupling constant. The NLO fixed-order predictions have been scrutinized at the technical level, using exactly the same inputs, setup and perturbative accuracy, in order to quantify the level of agreement of different implementations of the same calculation. A dedicated comparison, again at the technical level, of three codes that reach next-to-next-to-leading-order (NNLO) accuracy in quantum chromodynamics (QCD) for the total cross section has also been performed. These fixed-order results are a well-defined reference that allows a classification of the impact of higher-order sets of radiative corrections. Several examples of higher-order effects due to the strong or the EW interaction are discussed in this common framework. Also the combination of QCD and EW corrections is discussed, together with the ambiguities that affect the final result, due to the choice of a specific combination recipe. All the codes considered in this report have been run by the respective authors, and the results presented here constitute a benchmark that should be always checked/reproduced before any high-precision analysis is conducted based on these codes. In order to simplify these benchmarking procedures, the codes used in this report, together with the relevant input files and running instructions, can be found in a repository at https://twiki.cern.ch/twiki/bin/view/Main/DrellYanComparison

Parton distributions for the LHC run II

We present NNPDF3.0, the first set of parton distribution functions (PDFs) determined with a methodology validated by a closure test. NNPDF3.0 uses a global dataset including HERA-II deep-inelastic inclusive cross-sections, the combined HERA charm data, jet production from ATLAS and CMS, vector boson rapidity and transverse momentum distributions from ATLAS, CMS and LHCb, W+c data from CMS and top quark pair production total cross sections from ATLAS and CMS. Results are based on LO, NLO and NNLO QCD theory and also include electroweak corrections. To validate our methodology, we show that PDFs determined from pseudo-data generated from a known underlying law correctly reproduce the statistical distributions expected on the basis of the assumed experimental uncertainties. This closure test ensures that our methodological uncertainties are negligible in comparison to the generic theoretical and experimental uncertainties of PDF determination. This enables us to determine with confidence PDFs at different perturbative orders and using a variety of experimental datasets ranging from HERA-only up to a global set including the latest LHC results, all using precisely the same validated methodology. We explore some of the phenomenological implications of our results for the upcoming 13 TeV Run of the LHC, in particular for Higgs production cross-sections.Comment: 151 pages, 69 figures. More typos corrected: published versio

HE-LHC: The High-Energy Large Hadron Collider: Future Circular Collider Conceptual Design Report Volume 4

In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km tunnel infrastructure, as well as the physics opportunities of these two colliders, and a high-energy LHC, based on FCC-hh technology. This document constitutes the third volume of the FCC Conceptual Design Report, devoted to the hadron collider FCC-hh. It summarizes the FCC-hh physics discovery opportunities, presents the FCC-hh accelerator design, performance reach, and staged operation plan, discusses the underlying technologies, the civil engineering and technical infrastructure, and also sketches a possible implementation. Combining ingredients from the Large Hadron Collider (LHC), the high-luminosity LHC upgrade and adding novel technologies and approaches, the FCC-hh design aims at significantly extending the energy frontier to 100 TeV. Its unprecedented centre-of-mass collision energy will make the FCC-hh a unique instrument to explore physics beyond the Standard Model, offering great direct sensitivity to new physics and discoveries

FCC-ee: The Lepton Collider: Future Circular Collider Conceptual Design Report Volume 2

In response to the 2013 Update of the European Strategy for Particle Physics, the Future Circular Collider (FCC) study was launched, as an international collaboration hosted by CERN. This study covers a highest-luminosity high-energy lepton collider (FCC-ee) and an energy-frontier hadron collider (FCC-hh), which could, successively, be installed in the same 100 km tunnel. The scientific capabilities of the integrated FCC programme would serve the worldwide community throughout the 21st century. The FCC study also investigates an LHC energy upgrade, using FCC-hh technology. This document constitutes the second volume of the FCC Conceptual Design Report, devoted to the electron-positron collider FCC-ee. After summarizing the physics discovery opportunities, it presents the accelerator design, performance reach, a staged operation scenario, the underlying technologies, civil engineering, technical infrastructure, and an implementation plan. FCC-ee can be built with today’s technology. Most of the FCC-ee infrastructure could be reused for FCC-hh. Combining concepts from past and present lepton colliders and adding a few novel elements, the FCC-ee design promises outstandingly high luminosity. This will make the FCC-ee a unique precision instrument to study the heaviest known particles (Z, W and H bosons and the top quark), offering great direct and indirect sensitivity to new physics

FCC Physics Opportunities: Future Circular Collider Conceptual Design Report Volume 1

We review the physics opportunities of the Future Circular Collider, covering its e+e-, pp, ep and heavy ion programmes. We describe the measurement capabilities of each FCC component, addressing the study of electroweak, Higgs and strong interactions, the top quark and flavour, as well as phenomena beyond the Standard Model. We highlight the synergy and complementarity of the different colliders, which will contribute to a uniquely coherent and ambitious research programme, providing an unmatchable combination of precision and sensitivity to new physics