National Academy of Sciences of Belarus

Author(s): Collaboration, The ATLAS; Aad, G; Abat, E; Abdallah, J; Abdelalim, AA; Abdesselam, A; Abdinov, O; Abi, BA; Abolins, M; Abramowicz, H; Acerbi, E; Acharya, BS; Achenbach, R; Ackers, M; Adams, DL; Adamyan, F; Addy, TN; Aderholz, M; Adorisio, C; Adragna, P; Aharrouche, M; Ahlen, SP; Ahles, F; Ahmad, A; Ahmed, H; Aielli, G; Åkesson, PF; Åkesson, TPA; Akimov, AV; Alam, SM; Albert, J; Albrand, S; Aleksa, M; Aleksandrov, IN; Aleppo, M; Alessandria, F; Alexa, C; Alexander, G; Alexopoulos, T; Alimonti, G; Aliyev, M; Allport, PP; Allwood-Spiers, SE; Aloisio, A; Alonso, J; Alves, R; Alviggi, MG; Amako, K; Amaral, P; Amaral, SP; Ambrosini, G; Ambrosio, G; Amelung, C; Ammosov, VV; Amorim, A; Amram, N; Anastopoulos, C; Anderson, B; Anderson, KJ; Anderssen, EC; Andreazza, A; Andrei, V; Andricek, L; Andrieux, M-L; Anduaga, XS; Anghinolfi, F; Antonaki, A; Antonelli, M; Antonelli, S; Apsimon, R; Arabidze, G; Aracena, I; Arai, Y; Arce, ATH; Archambault, JP; Arguin, J-F; Arik, E; Arik, M; Arms, KE; Armstrong, SR; Arnaud, M; Arnault, C; Artamonov, A; Asai, S; Ask, S

The Large Hadron Collider (LHC) at CERN will extend the frontiers of particle physics with its
\nunprecedented high energy and luminosity. Inside the LHC, bunches of up to 1011 protons (p)
\nwill collide 40 million times per second to provide 14 TeV proton-proton collisions at a design
\nluminosity of 1034 cm􀀀2s􀀀1. The LHC will also collide heavy ions (A), in particular lead nuclei, at
\n5.5 TeV per nucleon pair, at a design luminosity of 1027 cm􀀀2s􀀀1.
\nThe high interaction rates, radiation doses, particle multiplicities and energies, as well as the
\nrequirements for precision measurements have set new standards for the design of particle detectors.
\nTwo general purpose detectors, ATLAS (A Toroidal LHC ApparatuS) and CMS (Compact
\nMuon Solenoid) have been built for probing p-p and A-A collisions.
\nThis paper presents a comprehensive overview of the ATLAS detector prior to the first LHC
\ncollisions, written as the installation of the ATLAS detector is nearing completion. This detector
\nrepresents the work of a large collaboration of several thousand physicists, engineers, technicians,
\nand students over a period of fifteen years of dedicated design, development, fabrication, and installation.

A measurement of the Higgs boson mass is presented based on the combined data samples of the ATLAS and CMS experiments at the CERN LHC in the H→γγ and H→ZZ→4ℓ decay channels. The results are obtained from a simultaneous fit to the reconstructed invariant mass peaks in the two channels and for the two experiments. The measured masses from the individual channels and the two experiments are found to be consistent among themselves. The combined measured mass of the Higgs boson is m_{H}=125.09±0.21 (stat)±0.11 (syst) GeV.

Combined ATLAS and CMS measurements of the Higgs boson production and decay rates, as well as constraints on its couplings to vector bosons and fermions, are presented. The combination is based on the analysis of five production processes, namely gluon fusion, vector boson fusion, and associated production with a W or a Z boson or a pair of top quarks, and of the six decay modes H → ZZ, W W , γγ, ττ, bb, and μμ. All results are reported assuming a value of 125.09 GeV for the Higgs boson mass, the result of the combined measurement by the ATLAS and CMS experiments. The analysis uses the CERN LHC proton-proton collision data recorded by the ATLAS and CMS experiments in 2011 and 2012, corresponding to integrated luminosities per experiment of approximately 5 fb$^{−1}$ at $\sqrt{s}$=7 TeV and 20 fb−1 at $\sqrt{s}$=8 TeV. The Higgs boson production and decay rates measured by the two experiments are combined within the context of three generic parameterisations: two based on cross sections and branching fractions, and one on ratios of coupling modifiers. Several interpretations of the measurements with more model-dependent parameterisations are also given. The combined signal yield relative to the Standard Model prediction is measured to be 1.09 ± 0.11. The combined measurements lead to observed significances for the vector boson fusion production process and for the H → ττ decay of 5.4 and 5.5 standard deviations, respectively. The data are consistent with the Standard Model predictions for all parameterisations considered.

Low-dimensional semiconductor structures, often referred to as nanocrystals or quantum dots, exhibit fascinating behavior and have a multitude of potential applications, especially in the field of communications. This book examines in detail the optical properties of these structures, giving full coverage of theoretical and experimental results, and discusses their technological applications. The author begins by setting out the basic physics of electron states in crystals (adopting a 'cluster-to-crystal' approach), and goes on to discuss the growth of nanocrystals, absorption and emission of light by nanocrystals, optical nonlinearities, interface effects, and photonic crystals. He illustrates the physical principles with references to actual devices such as novel light-emitters and optical switches.

During 2015 the ATLAS experiment recorded [Formula: see text] of proton-proton collision data at a centre-of-mass energy of [Formula: see text]. The ATLAS trigger system is a crucial component of the experiment, responsible for selecting events of interest at a recording rate of approximately 1 kHz from up to 40 MHz of collisions. This paper presents a short overview of the changes to the trigger and data acquisition systems during the first long shutdown of the LHC and shows the performance of the trigger system and its components based on the 2015 proton-proton collision data.

By using the ATLAS detector, observations have been made of a centrality-dependent dijet asymmetry in the collisions of lead ions at the Large Hadron Collider. In a sample of lead-lead events with a per-nucleon center of mass energy of 2.76 TeV, selected with a minimum bias trigger, jets are reconstructed in fine-grained, longitudinally segmented electromagnetic and hadronic calorimeters. The transverse energies of dijets in opposite hemispheres are observed to become systematically more unbalanced with increasing event centrality leading to a large number of events which contain highly asymmetric dijets. This is the first observation of an enhancement of events with such large dijet asymmetries, not observed in proton-proton collisions, which may point to an interpretation in terms of strong jet energy loss in a hot, dense medium.

Materials capable of field conversion, from magnetic to electric or vice versa, are of fundamental and technological importance. We report a giant magnetoelectric (ME) effect that results from stress-mediated electromagnetic coupling in bilayers and multilayers of nickel ferrite and lead zirconate titanate. Samples with layer thickness 10--200 \ensuremath{\mu}m were synthesized by doctor-blade techniques. The magnetoelectric voltage coefficient ${\ensuremath{\alpha}}_{\mathbf{E}}$ ranges from 460 mV/cm Oe in bilayers to 1500 mV/cm Oe for multilayers. The transverse effect is an order of magnitude stronger than longitudinal ${\ensuremath{\alpha}}_{\mathbf{E}}.$ The ME coefficient is maximum at room temperature and a general increase in ${\ensuremath{\alpha}}_{\mathbf{E}}$ is observed with increasing frequency. Data on the dependence of ${\ensuremath{\alpha}}_{\mathbf{E}}$ on volume fraction of the two phases and bias magnetic field are in excellent agreement with a theoretical model for a perfectly bonded bilayer.

BACKGROUND: After the Chernobyl nuclear power plant accident in April 1986, a large increase in the incidence of childhood thyroid cancer was reported in contaminated areas. Most of the radiation exposure to the thyroid was from iodine isotopes, especially 131I. We carried out a population-based case-control study of thyroid cancer in Belarus and the Russian Federation to evaluate the risk of thyroid cancer after exposure to radioactive iodine in childhood and to investigate environmental and host factors that may modify this risk. METHODS: We studied 276 case patients with thyroid cancer through 1998 and 1300 matched control subjects, all aged younger than 15 years at the time of the accident. Individual doses were estimated for each subject based on their whereabouts and dietary habits at the time of the accident and in following days, weeks, and years; their likely stable iodine status at the time of the accident was also evaluated. Data were analyzed by conditional logistic regression using several different models. All statistical tests were two-sided. RESULTS: A strong dose-response relationship was observed between radiation dose to the thyroid received in childhood and thyroid cancer risk (P<.001). For a dose of 1 Gy, the estimated odds ratio of thyroid cancer varied from 5.5 (95% confidence interval [CI] = 3.1 to 9.5) to 8.4 (95% CI = 4.1 to 17.3), depending on the risk model. A linear dose-response relationship was observed up to 1.5-2 Gy. The risk of radiation-related thyroid cancer was three times higher in iodine-deficient areas (relative risk [RR]= 3.2, 95% CI = 1.9 to 5.5) than elsewhere. Administration of potassium iodide as a dietary supplement reduced this risk of radiation-related thyroid cancer by a factor of 3 (RR = 0.34, 95% CI = 0.1 to 0.9, for consumption of potassium iodide versus no consumption). CONCLUSION: Exposure to (131)I in childhood is associated with an increased risk of thyroid cancer. Both iodine deficiency and iodine supplementation appear to modify this risk. These results have important public health implications: stable iodine supplementation in iodine-deficient populations may substantially reduce the risk of thyroid cancer related to radioactive iodines in case of exposure to radioactive iodines in childhood that may occur after radiation accidents or during medical diagnostic and therapeutic procedures.

collision data, measurements of the reconstruction efficiency, as well as of the momentum scale and resolution, are presented and compared to Monte Carlo simulations. The reconstruction efficiency is measured to be close to [Formula: see text] over most of the covered phase space ([Formula: see text] and [Formula: see text] GeV). The isolation efficiency varies between 93 and [Formula: see text] depending on the selection applied and on the momentum of the muon. Both efficiencies are well reproduced in simulation. In the central region of the detector, the momentum resolution is measured to be [Formula: see text] ([Formula: see text]) for muons from [Formula: see text] ([Formula: see text]) decays, and the momentum scale is known with an uncertainty of [Formula: see text]. In the region [Formula: see text], the [Formula: see text] resolution for muons from [Formula: see text] decays is [Formula: see text] while the precision of the momentum scale for low-[Formula: see text] muons from [Formula: see text] decays is about [Formula: see text].

Two-particle correlations in relative azimuthal angle ($\ensuremath{\Delta}\ensuremath{\phi}$) and pseudorapidity ($\ensuremath{\Delta}\ensuremath{\eta}$) are measured in $\sqrt{{s}_{\mathrm{NN}}}=5.02\text{ }\text{ }\mathrm{TeV}$ $p+\mathrm{Pb}$ collisions using the ATLAS detector at the LHC. The measurements are performed using approximately $1\text{ }\text{ }\ensuremath{\mu}{\mathrm{b}}^{\ensuremath{-}1}$ of data as a function of transverse momentum (${p}_{\mathrm{T}}$) and the transverse energy ($\ensuremath{\Sigma}{E}_{\mathrm{T}}^{\mathrm{Pb}}$) summed over $3.1&lt;\ensuremath{\eta}&lt;4.9$ in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range ($2&lt;|\ensuremath{\Delta}\ensuremath{\eta}|&lt;5$) ``near-side'' ($\ensuremath{\Delta}\ensuremath{\phi}\ensuremath{\sim}0$) correlation that grows rapidly with increasing $\ensuremath{\Sigma}{E}_{\mathrm{T}}^{\mathrm{Pb}}$. A long-range ``away-side'' ($\ensuremath{\Delta}\ensuremath{\phi}\ensuremath{\sim}\ensuremath{\pi}$) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small $\ensuremath{\Sigma}{E}_{\mathrm{T}}^{\mathrm{Pb}}$, is found to match the near-side correlation in magnitude, shape (in $\ensuremath{\Delta}\ensuremath{\eta}$ and $\ensuremath{\Delta}\ensuremath{\phi}$) and $\ensuremath{\Sigma}{E}_{\mathrm{T}}^{\mathrm{Pb}}$ dependence. The resultant $\ensuremath{\Delta}\ensuremath{\phi}$ correlation is approximately symmetric about $\ensuremath{\pi}/2$, and is consistent with a dominant $\mathrm{cos}2\ensuremath{\Delta}\ensuremath{\phi}$ modulation for all $\ensuremath{\Sigma}{E}_{\mathrm{T}}^{\mathrm{Pb}}$ ranges and particle ${p}_{\mathrm{T}}$.

The spread of mineral particles over southwestern, western, and central Europe resulting from a strong Saharan dust outbreak in October 2001 was observed at 10 stations of the European Aerosol Research Lidar Network (EARLINET). For the first time, an optically dense desert dust plume over Europe was characterized coherently with high vertical resolution on a continental scale. The main layer was located above the boundary layer (above 1‐km height above sea level (asl)) up to 3–5‐km height, and traces of dust particles reached heights of 7–8 km. The particle optical depth typically ranged from 0.1 to 0.5 above 1‐km height asl at the wavelength of 532 nm, and maximum values close to 0.8 were found over northern Germany. The lidar observations are in qualitative agreement with values of optical depth derived from Total Ozone Mapping Spectrometer (TOMS) data. Ten‐day backward trajectories clearly indicated the Sahara as the source region of the particles and revealed that the dust layer observed, e.g., over Belsk, Poland, crossed the EARLINET site Aberystwyth, UK, and southern Scandinavia 24–48 hours before. Lidar‐derived particle depolarization ratios, backscatter‐ and extinction‐related Ångström exponents, and extinction‐to‐backscatter ratios mainly ranged from 15 to 25%, −0.5 to 0.5, and 40–80 sr, respectively, within the lofted dust plumes. A few atmospheric model calculations are presented showing the dust concentration over Europe. The simulations were found to be consistent with the network observations.

CERN-LHC. Measurement of inclusive charged particle distributions in proton proton collisions at centre-of-mass energies 0.9, 2.36 and 7 TeV using a single-arm minimum-bias trigger. Distributions of charged particle multiplicity and its dependence on pseudorapidity and transverse momentum are presented from ~190 mub-1 of data at 7 Tev, ~7 mub-1 at 0.9 TeV, and ~0.1 mub-1 at 2.36 GeV. UPDATE 20/05/2016: A wrong point was removed from table 16.

Abstract The 2022 Roadmap is the next update in the series of Plasma Roadmaps published by Journal of Physics D with the intent to identify important outstanding challenges in the field of low-temperature plasma (LTP) physics and technology. The format of the Roadmap is the same as the previous Roadmaps representing the visions of 41 leading experts representing 21 countries and five continents in the various sub-fields of LTP science and technology. In recognition of the evolution in the field, several new topics have been introduced or given more prominence. These new topics and emphasis highlight increased interests in plasma-enabled additive manufacturing, soft materials, electrification of chemical conversions, plasma propulsion, extreme plasma regimes, plasmas in hypersonics, data-driven plasma science and technology and the contribution of LTP to combat COVID-19. In the last few decades, LTP science and technology has made a tremendously positive impact on our society. It is our hope that this roadmap will help continue this excellent track record over the next 5–10 years.

Abstract The normal spectral absorptance of a number of metal, ceramic and polymer powders susceptible to be utilised for selective laser sintering (SLS) technique was experimentally determined. The measurements were performed with two laser wavelengths of 1.06μm and 10.6μm obtained by using two lasers – Nd‐YAG and CO2 respectively. The change in the powder absorptance with time during laser processing was also investigated. The effect of the absorptance characteristics on the sintering process is discussed.

The discovery of brassinosteroids (BS) just over 20 years ago opened a new era in studies of bio-regulation in living organisms. Previously, the only known role of steroids as hormones was in animals and fungi; now a steroidal hormone in plants had been added. Progress in brassinosteroid research has been very rapid. Only 20 years passed between the discovery of brassinolide, the first member of the series, and the application of brassinosteroids in agriculture. Although the other plant hormones have been studied for a much longer period, there has not been similar development. Within the last couple of years two books on brassinosteroids (Khripach VA, Zhabinskii VN, de Groot A. 1999. Brassinosteroids—a new class of plant hormones . San Diego: Academic Press; Sakurai A, Yokota T, Clouse SD, eds. 1999. Brassinosteroids: steroidal plant hormones . Tokyo: Springer Verlag) have been published, but many new data have appeared since that time. Many of the more recent data is devoted to molecular biological aspects of BS and has helped to create a vision of their role in plants and their mechanisms of action. New discoveries of the physiological properties of BS allow us to consider them as highly promising, environmentally-friendly, natural substances suitable for wide application in plant protection and yield promotion in agriculture. This aspect of BS is the main subject of this Botanical Briefing. Copyright 2000 Annals of Botany Company

We argue that an astrophysical solution to the ultrahigh energy cosmic ray (UHECR) problem is viable. The detailed study of UHECR energy spectra is performed. The spectral features of extragalactic protons interacting with the cosmic microwave background (CMB) are calculated in a model-independent way. Using the power-law generation spectrum $\ensuremath{\propto}{E}^{\ensuremath{-}{\ensuremath{\gamma}}_{g}}$ as the only assumption, we analyze four features of the proton spectrum: the GZK cutoff, dip, bump, and the second dip. We found the dip, induced by electron-positron production on the CMB, to be the most robust feature, existing in energy range $1\ifmmode\times\else\texttimes\fi{}{10}^{18}--4\ifmmode\times\else\texttimes\fi{}{10}^{19}\text{ }\text{ }\mathrm{eV}$. Its shape is stable relative to various phenomena included in calculations: discreteness of the source distribution, different modes of UHE proton propagation (from rectilinear to diffusive), local overdensity or deficit of the sources, large-scale inhomogeneities in the universe, and interaction fluctuations. The dip is well confirmed by observations of the AGASA, HiRes, Fly's Eye, and Yakutsk detectors. With two free parameters (${\ensuremath{\gamma}}_{g}$ and flux normalization constant) the dip describes about 20 energy bins with ${\ensuremath{\chi}}^{2}/\mathrm{d}.\mathrm{o}.\mathrm{f}.\ensuremath{\approx}1$ for each experiment. The best fit is reached at ${\ensuremath{\gamma}}_{g}=2.7$, with the allowed range 2.55--2.75. The dip is used for energy calibration of the detectors. For each detector independently, the energy is shifted by factor $\ensuremath{\lambda}$ to reach the minimum ${\ensuremath{\chi}}^{2}$. We found ${\ensuremath{\lambda}}_{\mathrm{Ag}}=0.9$, ${\ensuremath{\lambda}}_{\mathrm{Hi}}=1.2$, and ${\ensuremath{\lambda}}_{\mathrm{Ya}}=0.75$ for the AGASA, HiRes, and Yakutsk detectors, respectively. Remarkably, after this energy shift the fluxes and spectra of all three detectors agree perfectly, with discrepancy between AGASA and HiRes at $E&gt;1\ifmmode\times\else\texttimes\fi{}{10}^{20}\text{ }\text{ }\mathrm{eV}$ being not statistically significant. The excellent agreement of the dip with observations should be considered as confirmation of UHE proton interaction with the CMB. The dip has two flattenings. The high energy flattening at $E\ensuremath{\approx}1\ifmmode\times\else\texttimes\fi{}{10}^{19}\text{ }\text{ }\mathrm{eV}$ automatically explains ankle, the feature observed in all experiments starting from the 1980s. The low-energy flattening at $E\ensuremath{\approx}1\ifmmode\times\else\texttimes\fi{}{10}^{18}\text{ }\text{ }\mathrm{eV}$ reproduces the transition to galactic cosmic rays. This transition is studied quantitatively in this work. Inclusion of primary nuclei with a fraction of more than 20% upsets the agreement of the dip with observations, which we interpret as an indication of the acceleration mechanism. We study in detail the formal problems of spectra calculations: energy losses (the new detailed calculations are presented), the analytic method of spectrum calculations, and the study of fluctuations with the help of a kinetic equation. The UHECR sources, AGN and GRBs, are studied in a model-dependent way, and acceleration is discussed. Based on the agreement of the dip with existing data, we make the robust prediction for the spectrum at $1\ifmmode\times\else\texttimes\fi{}{10}^{18}--1\ifmmode\times\else\texttimes\fi{}{10}^{20}\text{ }\text{ }\mathrm{eV}$ to be measured in the nearest future by the Auger detector. We also predict the spectral signature of nearby sources, if they are observed by Auger. This paper is long and contains many technical details. For those who are interested only in physical content we recommend the Introduction and Conclusions, which are written as autonomous parts of the paper.

Differential measurements of charged particle azimuthal anisotropy are presented for lead-lead collisions at s NN = 2.76 TeV with the ATLAS detector at the LHC, based on an integrated luminosity of approximately 8 b -1 . This anisotropy is characterized via a Fourier expansion of the distribution of charged particles in azimuthal angle relative to the reaction plane, with the coefficients v n denoting the magnitude of the anisotropy. Significant v 2 -v 6 values are obtained as a function of transverse momentum (0.5 < p T < 20 GeV), pseudorapidity (|| < 2.5), and centrality using an event plane method. The v n values for n 3 are found to vary weakly with both and centrality, and their p T dependencies are found to follow an approximate scaling relation,

Combined measurements of Higgs boson production and decay using up to 80

have shape and location information, which is exploited to apply a local energy calibration and corrections depending on the nature of the cluster. Topological cell clustering is established as a well-performing calorimeter signal definition for jet and missing transverse momentum reconstruction in ATLAS.