Serguei Volkov

The performance of the LHCb Muon system and its stability across the full 2010 data taking with LHC running at ps = 7 TeV energy is studied. The optimization of the detector setting and the time calibration performed with the first collisions delivered by LHC is described. Particle rates, measured for the wide range of luminosities and beam operation conditions experienced during the run, are compared with the values expected from simulation. The space and time alignment of the detectors, chamber efficiency, time resolution and cluster size are evaluated. The detector performance is found to be as expected from specifications or better. Notably the overall efficiency is well above the design requirements

The experiment Neutrino-4 had started in 2014 with a detector model and then was continued with a full-scale detector in 2016 - 2021. In this article we describe all steps of preparatory work on this experiment. We present all results of the Neutrino-4 experiment with increased statistical accuracy provided to date. The experimental setup is constructed to measure the flux and spectrum of the reactor antineutrinos as a function of distance to the center of the active zone of the SM-3 reactor (Dimitrovgrad, Russia) in the range of 6 - 12 meters. Using all the collected data, we performed a model-independent analysis to determine the oscillation parameters $\Delta m_{14}^2$ and $\sin^22\theta_{14}$. The method of coherent summation of measurement results allows to directly demonstrate the oscillation effect. We present the analysis of possible systematic errors and the MC model of the experiment, which considers the possibility of the effect manifestation at the present precision level. As a result of the analysis, we can conclude that at currently available statistical accuracy we observe the oscillations at the $2.9\sigma$ level with parameters $\Delta m_{14}^2=(7.3\pm0.13_{st}\pm1.16_{sys})\text{eV}^2 = (7.3\pm1.17)\text{eV}^2$ and $\sin^22\theta_{14}= 0.36\pm0.12_{stat}(2.9\sigma)$. Monte Carlo based statistical analysis gave estimation of confidence level at $2.7\sigma$. We plan to improve the currently working experimental setup and create a completely new setup in order to increase the accuracy of the experiment by 3 times. We also provide a brief analysis of the general experimental situation in the search for sterile neutrinos.

Major Atmospheric Gamma Imaging Cherenkov telescope is starting its operations with a set of engineering runs to tune the telescope subsystem elements to be ready for the first physics campaign. Many technical improvements have been developed and implemented in several elements of the telescope to reach the lowest energy threshold ever obtained by an Imaging Atmospheric Cherenkov Telescope. A general description of the telescope is presented. The commissioning of the telescope's elements is described and the expected performances are reviewed with the final detector set-up.

NeuLAND (New Large-Area Neutron Detector) is the next-generation neutron detector for the R3B (Reactions with Relativistic Radioactive Beams) experiment at FAIR (Facility for Antiproton and Ion Research). NeuLAND detects neutrons with energies from 100 to 1000 MeV, featuring a high detection efficiency, a high spatial and time resolution, and a large multi-neutron reconstruction efficiency. This is achieved by a highly granular design of organic scintillators: 3000 individual submodules with a size of 5 × 5 × 250 cm3 are arranged in 30 double planes with 100 submodules each, providing an active area of 250 × 250 cm2 and a total depth of 3 m. The spatial resolution due to the granularity together with a time resolution of σt≤ 150 ps ensures high-resolution capabilities. In conjunction with calorimetric properties, a multi-neutron reconstruction efficiency of 50% to 70% for four-neutron events will be achieved, depending on both the emission scenario and the boundary conditions allowed for the reconstruction method. We present in this paper the final design of the detector as well as results from test measurements and simulations on which this design is based.

The design and operation of precision drift chambers with multisampling as well as the concepts and methods for reaching an extraordinary degree of precision in mechanics and calibration are described. Specific instruments were developed for this purpose. The concept of reproducible positioning and the implementation to 30 μm accuracy, showing stability over three years, is given. Calibration and analysis with UV-laser and cosmic test measurements are outlined with the critical results. The experience of calibration and reliability of the large system in an actual L3 running experiment is analyzed. The resolution under “battle conditions” at LEP resulted in Δpp = (2.50±0.04)% at 45.6 GeV and will be presented in detail. The concept is well suited for future TeV energies.

A measurement of the Higgs boson Yukawa coupling to the top quark is presented using proton-proton collision data at $\sqrt{s} =$ 13 TeV, corresponding to an integrated luminosity of 137 fb$^{-1}$, recorded with the CMS detector. The coupling strength with respect to the standard model value, $Y_\mathrm{t}$, is determined from kinematic distributions in $\mathrm{t\bar{t}}$ final states containing ee, $μμ$, or e$μ$ pairs. Variations of the Yukawa coupling strength lead to modified distributions for $\mathrm{t\bar{t}}$ production. In particular, the distributions of the mass of the $\mathrm{t\bar{t}}$ system and the rapidity difference of the top quark and antiquark are sensitive to the value of $Y_\mathrm{t}$. The measurement yields a best fit value of $Y_\mathrm{t} =$ 1.16 $^{+0.24}_{-0.35}$, bounding $Y_\mathrm{t}$ $\lt$ 1.54 at a 95% confidence level.

The differential cross section for elastic scattering of 1 GeV protons from 3He nuclei has been measured. The problem of the filling of the minima is discussed. It is shown that the shallow minimum observed in the experiment may be described by Glauber model calculations with a t-dependent ratio of real to imaginary pN-amplitudes.

The polarization has been measured in the elastic scattering of 1 GeV protons on 12C. The measurements have been performed by the double-scattering method using a magnetic spectrometer with an energy resolution of 2.5 MeV. The data obtained are fitted with the Glauber model.

Ground-based Cherenkov telescopes have made in recent years important contributions to high energy gamma-ray astronomy.A lower energy threshold, considerably below 100 GeV, and improved sensitivity will be key parameters to extend their role.A lower threshold will permit these instruments to cover wavelengths with good overlap with satellite experiments, thus providing essential complementary information.The latest generation of Imaging Air Cherenkov Telescopes was built with this criterion in mind.Preliminary studies concerning further progress in the same direction have started.We discuss in this contribution the astrophysics and physics arguments for lowering the observable energy threshold as far as the Cherenkov technique permits, and the ensuing complementarity to results obtained with a GLAST-like satellite.

Abstract A detector system for measurement of angular correlations in binary fission reactions, which are induced by 1 GeV protons, is described. A new type of parallel plate avalanche counsisting of two grids delivers the start signal for the time-of-flight measurement for the correlated fragments. With this detector we obtained an energy loss of 7.8 MeV and an intrinsic time resolution of τ=320 ps for spontaneous fission fragments from a 252Cf source. A large area position-sensitive parallel plate avalanche counter (3.5×18 cm2) with delay-line read-out measures the coordinate of the complementary fragment within an accuracy of 4.3 mm (corresponding to 1.3°). The spatial resolution has been measured for α-particles and fission fragments under different conditions. The reliability of the developed detector system was checked experimentally with U and Bi targets, which were bombarded with 1 GeV protons.

Two CMS production Cathode Strip Chambers were tested for aging effects in a high-radiation environment at the Gamma Irradiation Facility at CERN. The chambers were irradiated over a large area: in total, about 2.1 m2 or 700 m of wire in each chamber. The 40% Ar+50% CO2+10% CF4 gas mixture was provided by an open-loop gas system for one of the chambers and by a closed-loop re-circulating gas system for the other. After an accumulation of 0.3–0.4 C/cm of a wire, equivalent to about 30–50 years of operation at peak LHC luminosity, no significant changes in gas gain, chamber efficiency and wire signal noise were observed for either of the two chambers. The only consistent signs of aging were a small increase in dark current from ∼2 to ∼10 nA per plane of 600 wires and a decrease of strip-to-strip resistance from 1000 to 10–100 GΩ. Disassembly of the chambers revealed deposits on the cathode planes, while the anode wires remained fairly clean.

A study of inelastic scattering of polarized $3.73\ensuremath{-}\mathrm{GeV}/c$ deuterons on protons in the energy region of the Roper $N(1440)$ and the $\ensuremath{\Delta}(1232)$ resonances excitation has been performed in an exclusive experiment at LNS (Laboratoire National SATURNE, Saclay, France) using the SPES4-$\ensuremath{\pi}$ setup. Tensor and vector analyzing powers of pion production for the reactions: $d+\stackrel{\ensuremath{\rightarrow}}{p}d+n+{\ensuremath{\pi}}^{+},$ $d+\stackrel{\ensuremath{\rightarrow}}{p}d+p+{\ensuremath{\pi}}^{0},$ $d+\stackrel{\ensuremath{\rightarrow}}{p}d+N+\ensuremath{\pi}\ensuremath{\pi}$ have been measured as functions of the squared deuteron four-momentum transfer t, of the effective mass of the subsystems $N\ensuremath{\pi},$ $N\ensuremath{\pi}\ensuremath{\pi},$ and of the pion emission angle. A strong dependence of these analyzing powers upon the pion emission angle is observed. It is found that ${A}_{\mathrm{yy}}$ values for the considered reaction channels are systematically larger than the known inclusive ${p(d,d}^{\ensuremath{'}})X$ world data at the nearest beam energy.

The paper describes the spectrometric system “SPES4–π” used at the National Laboratory Saturne (CE Saclay, France) for the exclusive study of the baryon resonance excitation in inelastic α and d scattering on the proton, as well as coherent pion production in charge exchange reactions. The system consists of the magnetic spectrometer SPES4 and two wide-aperture position-sensitive detector arrays, equipped with wire chambers and scintillator hodoscopes, installed around a large-gap C-shape dipole magnet.

The L3 detector is designed to measure the muon momentum with a 2% resolution at p = 45 GeV/c. We discuss here the systems we developed to reach the required accuracy and control the mechanical alignment at running time. We also report on the test done on the muon spectrometer with UV lasers and cosmic rays.

The L3 muon spectrometer is presented. Characteristics, useful for experiments at future accelerators, are highlighted. Particular emphasis is given to the systems envisaged to keep the error on the relative alignment of detectors below 30 μm and so reach a momentum resolution Δpp = 2% at p = 45 GeV/c.

Semiexclusive measurements of the two-pion-production $p(\ensuremath{\alpha},{\ensuremath{\alpha}}^{'})p\ensuremath{\pi}\ensuremath{\pi}$ reaction have been carried out at an energy of ${E}_{\ensuremath{\alpha}}=4.2$ GeV at the Saturne-II (Saclay) accelerator with the SPES4-\ensuremath{\pi} installation. This reaction was investigated by simultaneous registration of the scattered \ensuremath{\alpha} particle and the secondary proton. The obtained results show that the two-pion production in inelastic \ensuremath{\alpha}-particle scattering on the proton at the energy of the experiment proceeds mainly through excitation in the target proton of the Roper resonance and its decay with emission of two pions in the isospin $I=0,S$-wave state.

In the Compact Muon Solenoid (CMS) experiment, muon detection in the forward direction is accomplished by cathode strip chambers (CSC). These detectors identify muons, provide a fast muon trigger, and give a precise measurement of the muon trajectory. There are 468 six-plane CSCs in the system. The efficiency of finding muon trigger primitives (muon track segments) was studied using 36 CMS CSCs and cosmic ray muons during the Magnet Test and Cosmic Challenge (MTCC) exercise conducted by the CMS experiment in 2006. In contrast to earlier studies that used muon beams to illuminate a very small chamber area (<0.01m2), results presented in this paper were obtained by many installed CSCs operating in situ over an area of ≈23m2 as a part of the CMS experiment. The efficiency of finding two-dimensional trigger primitives within six-layer chambers was found to be 99.93±0.03%. These segments, found by the CSC electronics within 800 ns after the passing of a muon through the chambers, are the input information for the Level-1 muon trigger and, also, are a necessary condition for chambers to be read out by the Data Acquisition System.

In the experiment &amp;quot;Neutrino-4&amp;quot; on the search for a sterile neutrino, the effect of oscillations was found at a confidence level of 3 standard deviations. In order to significantly increase the accuracy of the experiment, a second neutrino laboratory is created at the SM-3 reactor (Dimitrovgrad, Russia) and a new neutrino detector is developed. The scintillation-type detector consists of 4 modules having a multi-sectional structure with a horizontal arrangement of 100 sections with PMTs located on both sides of the section. The possibility of increasing the accuracy of the experiment by a factor of 2.7 is shown, which will make it possible to achieve a confidence level of more than 5 standard deviations and answer the question of the existence of a sterile neutrino. Keywords: sterile neutrino, reactor antineutrino.

Association of Cardiovascular Surgeons of Russia Russian Society of Cardiology (RSC) Association of Pediatric Cardiologists of Russia Russian Scientific Society of Specialists in X-Ray Endovascular Diagnostics and Treatment All-Russian Public Organization for the Promotion of Radiation Diagnostics and Therapy "Russian Society of Radiologists and Radiologists". Task Force members declared no financial support/conflicts of interest. If conflicts of interest were reported, the member(s) of the working group was (were) excluded from the discussion of the sections related to the area of conflict of interest.

The MAGIC telescope, presently at its commissioning phase, will become fully operative by the end of 2003. Placed at the Roque de los Muchachos Observatory (ORM) on the island of La Palma, MAGIC is the largest among new generation ground-based gamma ray telescopes, and will reach an energy threshold as low as 30 GeV. The range of the electromagnetic spectrum between 10 and 250 GeV remains to date mostly unexplored. Observations in this energy region are expected to provide key data for the understanding of a wide variety of astrophysical phenomena belonging to the so-called "non thermal Universe", like the processes in the nuclei of active galaxies, the radiation mechanisms of pulsars and supernova remnants, and the enigmatic gamma-ray bursts. An overview of the telescope and its physics goals is presented.

The LHCb Muon system performance is presented using cosmic ray events collected in 2009. These events allowed to test and optimize the detector configuration before the LHC start. The space and time alignment and the measurement of chamber efficiency, time resolution and cluster size are described in detail. The results are in agreement with the expected detector performance.

The article gives a detailed analysis of the classification of vehicles, public and freight transport modes. Next it is described the instrument creating technology to automate the traffic flow, according to the classification considered the composition of the traffic flow. Also described are the main characteristics of this device.

The coincidence cross section and polarization have been measured for the proton-deuteron break-up reaction pD→ppn at 1 GeV in a kinematically complete experiment. Two final protons from the reaction were detected in coincidence by means of a two-arm spectrometer at non-symmetric scattering angles θ1=19°–27°, θ2=61° in the momentum range of the neutron-spectator up to 0.3 GeV/c. At kinematic conditions of the experiment the coincidence cross section is well described in the framework of the single scattering impulse approximation with the Paris wave function of the deuteron. The polarization is also in good agreement with IA predictions.

We discuss preliminary studies concerning a large-diameter gamma-ray telescope, to be part of an array of telescopes installed at the existing observation site on the Canary island of La Palma. One of the telescopes in the array will be MAGIC, presently the largest existing gamma ray telescope and the most performant world wide at low energy. A second telescope of the same class is under construction. Eventually, we will want to install one or more devices giving access to even lower gamma-ray energy; they will be larger than MAGIC by roughly a linear factor two, and are code-named ECO-1000 (for a mirror surface of 1000 sq.m.). We discuss the technologies needed to reach the physical low-energy limit. They exist at the component level, but have to be field-tested; we propose to implement and integrate the most critical components in a MAGIC-class telescope, such that the eventual extrapolation to a larger device becomes a fully predictable step. If financing can be found, such tests can be completed on a timescale such that a proposal for the first true low-theshold (< 8 GeV) telescope can be made in 2007, and its construction completed in 2009/2010.

Measurements of cosmic rays in the L3 multisampling chambers are presented. The study of tracks with polar angles from 30° < θ < 130° w.r.t. the wires show increasing pulse height like 1/sin θ. Using inclined tracks, we find a ±1.5 cm region of reduced accuracy near the glass supports of the 5.4 m long wires.

This is a brief description of the forward spectrometer which was used as a part of SPES4π installation for an exclusive investigation of the p(α,α 1)X and p(→ d,d 1)X reactions at the SATURNE-II accelerator (CE Saclay). The spectrometer was designed to register the products of the recoil particle decay and to select the specific channels of the reaction. It consists of a set of multiwire drift chambers and scintillation counter hodoscope and was especially adapted for the operation close to a high intensity direct beam of the accelerated particles. The main parameters of the spectrometer and the results of its test are presented.

The excitation mechanisms and properties of broad hadronic resonances in nuclei, which are intimately related with nuclear medium response on high energy excitations, have attracted much attention during last decade. Recently, a new step in these investigations was taken: inelastic p(d, d 1) scattering of polarized deuterons at momentum of 3.73 GeV/c was studied in an exclusive-type experiment at Saclay (exp. 278C), using the SPES-4π spectrometer. First (preliminary) results of this experiment are reported in this talk as well as data of inclusive-type experiments performed in Dubna. Data on the tensor analyzing power T 20 of genuine elastic p(d,p)d backward (c.m.) scattering are also reported.

Measurements with high-rate two-dimensional imaging gaseous detectors require an adequate data acquisition system which allows to handle and store the detector information. For this purpose, a transient recorder system has been developed and tested at the University of Siegen. In contrast to many today’s systems there is no memory needed to store information which is redundant and not used for the final image reconstruction. Some current applications and measurements of the transient recorder system will be presented. It results that high rates up to 100 MHz can be processed without dead time loss at short time scale. However, also the problem of handling the massive data flux in the backend electronics needs to be addressed. Currently the avarage data acquisition time is limited e.g. by the PCI Bus to typically 1–2 MHz/4 Bytes. Another limitation is the global trigger which has been applied to the system. To solve these problems, some basic ideas about local asynchronous and parallel readout for applications in pixel detectors with big sensitive areas are discussed.

The end cap detector based on multimodule construction has been designed and produced for the L3 experiment. The purpose of this article is to present a fruitful approach for solving the complex problem of selecting a set of strongly interrelated design parameters to satisfy performance criteria in the face of severe environmental and space constraints. The design principle of the end cap drift chamber affected by a complex of external problems caused by the layout is reviewed. It is shown that in the framework of detailed consideration of each parameter, a good space–time linearity, spatial and angular resolution is obtainable. The results of experimental tests are presented.

В статье рассматривается новый подход к решению проблемы схемотехнического моделирования сбоев от тяжелых заряженных частиц (ТЗЧ) в интегральных схемах, который позволяет проектировать библиотечные элементы ИС с заданным уровнем радиационной стойкости.

The strong Coulomb field created in ultrarelativistic heavy ion collisions is expected to produce a rapidity-dependent difference ($\Delta v_2$) in the second Fourier coefficient of the azimuthal distribution (elliptic flow, $v_2$) between $\mathrm{D}^0$ ($\mathrm{\bar{u}c}$) and $\overline{\mathrm{D}}^0$ ($\mathrm{u\bar{c}}$) mesons. Motivated by the search for evidence of this field, the CMS detector at the LHC is used to perform the first measurement of $\Delta v_2$. The rapidity-averaged value is found to be $\langle\Delta v_2 \rangle =$ 0.001 $\pm$ 0.001 (stat) $\pm$ 0.003 (syst) in PbPb collisions at $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV. In addition, the influence of the collision geometry is explored by measuring the $\mathrm{D}^0$ and $\overline{\mathrm{D}}^0$ mesons $v_2$ and triangular flow coefficient ($v_3$) as functions of rapidity, transverse momentum ($p_\mathrm{T}$), and event centrality (a measure of the overlap of the two Pb nuclei). A clear centrality dependence of prompt $\mathrm{D}^0$ meson $v_2$ values is observed, while the $v_3$ is largely independent of centrality. These trends are consistent with expectations of flow driven by the initial-state geometry.

The experiment Neutrino-4 had started in 2014 with a detector model and then was continued with a full-scale detector in 2016 - 2021. In this article we describe all steps of preparatory work on this experiment. We present all results of the Neutrino-4 experiment with increased statistical accuracy provided to date. The experimental setup is constructed to measure the flux and spectrum of the reactor antineutrinos as a function of distance to the center of the active zone of the SM-3 reactor (Dimitrovgrad, Russia) in the range of 6 - 12 meters. Using all the collected data, we performed a model-independent analysis to determine the oscillation parameters $\Delta m_{14}^2$ and $\sin^22\theta_{14}$. The method of coherent summation of measurement results allows to directly demonstrate the oscillation effect. We present the analysis of possible systematic errors and the MC model of the experiment, which considers the possibility of the effect manifestation at the present precision level. As a result of the analysis, we can conclude that at currently available statistical accuracy we observe the oscillations at the $2.9\sigma$ level with parameters $\Delta m_{14}^2=(7.3\pm0.13_{st}\pm1.16_{sys})\text{eV}^2 = (7.3\pm1.17)\text{eV}^2$ and $\sin^22\theta_{14}= 0.36\pm0.12_{stat}(2.9\sigma)$. Monte Carlo based statistical analysis gave estimation of confidence level at $2.7\sigma$. We plan to improve the currently working experimental setup and create a completely new setup in order to increase the accuracy of the experiment by 3 times. We also provide a brief analysis of the general experimental situation in the search for sterile neutrinos.

The CMS experiment at the LHC has measured the differential cross sections of Z bosons decaying to pairs of leptons, as functions of transverse momentum and rapidity, in lead-lead collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The measured Z boson elliptic azimuthal anisotropy coefficient is compatible with zero, showing that Z bosons do not experience significant final-state interactions in the medium produced in the collision. Yields of Z bosons are compared to Glauber model predictions and are found to deviate from these expectations in peripheral collisions, indicating the presence of initial collision geometry and centrality selection effects. The precision of the measurement allows, for the first time, for a data-driven determination of the nucleon-nucleon integrated luminosity as a function of lead-lead centrality, thereby eliminating the need for its estimation based on a Glauber model.

Differential cross sections for elastic scattering of 1-GeV protons have been measured for the nuclei /sup 90/Zr and /sup 208/Pb. The experimental data are analyzed in terms of Glauber diffraction theory. The parameters of the spatial distributions of the density of nuclear matter and the parameters of the neutron distribution have been determined. The difference found for the rms radii of the neutron and proton distributions ..delta..=/sub n//sup 1/2/--/sub p//sup 1/2/ in /sup 90/Zr and /sup 208/Pb is respectively ..delta../sub 90/=0.09 +- 0.05 F and ..delta../sub 208/=0.03 +- 0.05 F.

A missing-mass correlation spectrometer with resolution 4 MeV (FWHM) has been used to study the (p,2p) and (p,np) reaction at a proton energy T0 = 1.0 GeV in the nuclei WLi, XLi, ZBe, B, B, SC, and WO. The separation-energy spectra and the relative probabilities of knockout of protons and neutrons from the S and P shells are analyzed. The relation between the data obtained and the spatial distribution of protons and neutrons in the nuclei is discussed.