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Field Equations in the Complex Quaternion Spaces
https://cds.cern.ch/record/2011943
The paper aims to adopt the complex quaternion and octonion to formulate the field equations for electromagnetic and gravitational fields. Applying the octonionic representation enables one single definition to combine some physics contents of two fields, which were considered to be independent of each other in the past. J. C. Maxwell applied simultaneously the vector terminology and the quaternion analysis to depict the electromagnetic theory. This method edified the paper to introduce the quaternion and octonion spaces into the field theory, in order to describe the physical feature of electromagnetic and gravitational fields, while their coordinates are able to be the complex number. The octonion space can be separated into two subspaces, the quaternion space and the S-quaternion space. In the quaternion space, it is able to infer the field potential, field strength, field source, field equations, and so forth, in the gravitational field. In the S-quaternion space, it is able to deduce the field potential, field strength, field source, and so forth, in the electromagnetic field. The results reveal that the quaternion space is appropriate to describe the gravitational features; meanwhile the S-quaternion space is proper to depict the electromagnetic features.Weng, Zi-HuaFri, 24 Apr 2015 05:49:40 GMT06 Apr 2015arXiv:1504.06182https://cds.cern.ch/record/2011943Yarkovsky effect in Generalized Photogravitational 3-Bodies Problem
https://cds.cern.ch/record/2011942
Here is presented a generalization of photogravitational restricted 3-bodies problem to the case of influence of Yarkovsky effect, which is known as reason of additional infinitesimal acceleration of a small bodies in the space (due to anisotropic re-emission of absorbed energy from the sun, other stellar sources). Asteroid is supposed to move under the influence of gravitational forces from 2 massive bodies (which are rotating around their common centre of masses on Kepler trajectories), as well under the influence of pressure of light from both the primaries. Analyzing the ODE system of motion, we explore the existense of equilibrium points for a small body (asteroid) in the case when the 2-nd primary is non-oblate spheroid. In such a case, it is proved the existence of maximally 256 different non-planar libration points in generalized photogravitational restricted 3-bodies problem when we take into consideration even a small Yarkovsky effect.Ershkov, Sergey VFri, 24 Apr 2015 05:49:40 GMT31 Mar 2015arXiv:1504.06181https://cds.cern.ch/record/2011942Automated weighing by sequential inference in dynamic environments
https://cds.cern.ch/record/2011925
We demonstrate sequential mass inference of a suspended bag of milk powder from simulated measurements of the vertical force component at the pivot while the bag is being filled. We compare the predictions of various sequential inference methods both with and without a physics model to capture the system dynamics. We find that non-augmented and augmented-state unscented Kalman filters (UKFs) in conjunction with a physics model of a pendulum of varying mass and length provide rapid and accurate predictions of the milk powder mass as a function of time. The UKFs outperform the other method tested - a particle filter. Moreover, inference methods which incorporate a physics model outperform equivalent algorithms which do not.Martin, A DMolteno, T C AFri, 24 Apr 2015 05:49:38 GMT22 Apr 2015arXiv:1504.06009https://cds.cern.ch/record/2011925Nuclear polarization study: New frontiers for tests of QED in heavy highly charged ions
https://cds.cern.ch/record/2011918
A systematic investigation of the nuclear-polarization effects in one- and few-electron heavy ions is presented. The nuclear-polarization corrections in the zeroth and first orders in $1/Z$ are evaluated to the binding energies, the hyperfine splitting, and the bound-electron g factor. It is shown, that the nuclear-polarization contributions can be substantially canceled simultaneously with the rigid nuclear corrections. This allows for new prospects for probing the QED effects in strong electromagnetic field and the determination of fundamental constants.Volotka, Andrey VPlunien, GünterFri, 24 Apr 2015 05:49:38 GMT22 Apr 2015arXiv:1504.05888https://cds.cern.ch/record/2011918Many-electron QED corrections to the g factor of lithiumlike ions
https://cds.cern.ch/record/2011914
A rigorous QED evaluation of the two-photon exchange corrections to the g factor of lithiumlike ions is presented. The screened self-energy corrections are calculated for the intermediate-$Z$ region and its accuracy for the high-$Z$ region is essentially improved in comparison with that of previous calculations. As a result, the theoretical accuracy of the g factor of lithiumlike ions is significantly increased. The theoretical prediction obtained for the g factor of $^{28}$Si$^{11+}$ ${\rm g}_{\rm th} = 2.000\,889\,892(8)$ is in an excellent agreement with the corresponding experimental value ${\rm g}_{\rm exp} = 2.000\,889\,889\,9(21)$ [A. Wagner et al., Phys. Rev. Lett. 110, 033003 (2013)].Volotka, A VGlazov, D AShabaev, V MTupitsyn, I IPlunien, GFri, 24 Apr 2015 05:49:38 GMT22 Apr 2015arXiv:1504.05856https://cds.cern.ch/record/2011914A Study of Correlations in the Stock Market
https://cds.cern.ch/record/2011912
We study the various sectors of the Bombay Stock Exchange(BSE) for a period of 8 years from April 2006 - March 2014. Using the data of daily returns of a period of eight years we make a direct model free analysis of the pattern of the sectorial indices movement and the correlations among them. Our analysis shows significant auto correlation among the individual sectors and also strong cross-correlation among sectors. We also find that auto correlations in some of the sectors persist in time. This is a very significant result and has not been reported so far in Indian context These findings will be very useful in model building for prediction of price movement of equities, derivatives and portfolio management. We show that the Random Walk Hypothesis is not applicable in modeling the Indian market and Mean-Variance-Skewness-Kurtosis based portfolio optimization might be required. We also find that almost all sectors are highly correlated during large fluctuation periods and have only moderate correlation during normal periods.Sharma, ChandradewBanerjee, KinjalFri, 24 Apr 2015 05:49:37 GMT22 Apr 2015arXiv:1504.05844https://cds.cern.ch/record/2011912Accessing electronic correlations by half-cycle pulses and time-resolved spectroscopy
https://cds.cern.ch/record/2011881
Ultrashort non-resonant electromagnetic pulses applied to effective one-electron systems may operate on the electronic state as a position or momentum translation operator. As derived here, extension to many-body correlated systems exposes qualitatively new aspects. For instance, to the lowest order in the electric field intensity the action of the pulse is expressible in terms of the two-body reduced density matrix enabling thus to probe various facets of electronic correlations. As an experimental realization we propose a pump-probe scheme in which after a weak, swift "kick" by the non-resonant pulse the survival probability for remaining in the initial state is measured. This probability we correlate to the two-body reduced density matrix. Since the strength of electronic correlation is bond-length sensitive, measuring the survival probability may allow for a direct insight into the bond-dependent two-body correlation in the ground state. As an illustration, full numerical calculations for two molecular systems are provided and different measures of electronic correlations are analyzed.Pavlyukh, YBerakdar, JFri, 24 Apr 2015 05:49:35 GMT21 Apr 2015arXiv:1504.05458https://cds.cern.ch/record/2011881T-matrix in discrete oscillator representation
https://cds.cern.ch/record/2011877
We investigate T-matrix for bound and continuous-spectrum states in the discrete oscillator representation. The investigation is carried out for a model problem - the particle in the field of a central potential. A system of linear equations is derived to determine the coefficients of the T-matrix expansion in the oscillator functions. We selected four potentials (Gaussian, exponential, Yukawa, and square-well ones) to demonstrate peculiarities of the T-matrix and its dependence on the potential shape. We also study how the T-matrix expansion coefficients depend on the parameters of the oscillator basis such as the oscillator length and the number of basis functions involved in calculations.Vasilevsky, V SSoloha-Klymchak, M DFri, 24 Apr 2015 05:49:24 GMT22 Apr 2015arXiv:1504.05729https://cds.cern.ch/record/2011877Critical Theory of Two-Dimensional Mott Transition: Integrability and Hilbert Space Mapping
https://cds.cern.ch/record/2011855
We reconsider the Mott transition in the context of a two-dimensional fermion model with density-density coupling. We exhibit a Hilbert space mapping between the original model and the Double Lattice Chern-Simons theory at the critical point by use of the representation theory of the q-oscillator and Weyl algebras. The transition is further characterized by the ground state modification. The explicit mapping provides a new tool to further probe and test the detailed physical properties of the fermionic lattice model considered here and to enhance our understanding of the Mott transition(s).Bottesi, Federico LZemba, Guillermo RFri, 24 Apr 2015 05:48:44 GMT22 Apr 2015arXiv:1504.05772https://cds.cern.ch/record/2011855Lorenz gauge quantization in conformally flat spacetimes
https://cds.cern.ch/record/2011797
Recently it was shown that Dirac's method of quantizing constrained dynamical systems can be used to impose the Lorenz gauge condition in a four-dimensional cosmological spacetime. In this paper we use Dirac's method to impose the Lorenz gauge condition in a general four-dimensional conformally flat spacetime and find that there is no particle production. We show that in cosmological spacetimes with dimension $D\neq 4$ there will be particle production when the scale factor changes, and we calculate the particle production due to a sudden change.Cresswell, Jesse CVollick, Dan NFri, 24 Apr 2015 05:46:28 GMT22 Apr 2015arXiv:1504.05914https://cds.cern.ch/record/2011797Standard Electroweak Interactions in Gravitational Theory with Chameleon Field and Torsion
https://cds.cern.ch/record/2011792
We propose a version of a gravitational theory with the torsion field, induced by the chameleon field. Following Hojman et al. Phys. Rev. D17, 3141 (1976) the results, obtained in Phys. Rev. D90, 045040 (2014), are generalised by extending the Einstein gravity to the Einstein-Cartan gravity with the torsion field as a gradient of the chameleon field through a modification of local gauge invariance of minimal coupling in the Weinberg-Salam electroweak model. The contributions of the chameleon (torsion) field to the observables of electromagnetic and weak processes are calculated. Since in our approach the chameleon-photon coupling constant beta_(gamma) is equal to the chameleon-matter coupling constant beta, i.e. beta_(gamma) = beta, the experimental constraints on beta, obtained in terrestrial laboratories by T. Jenke et al. (Phys. Rev. Lett. 112, 115105 (2014)) and by H. Lemmel et al. (Phys. Lett. B743, 310 (2015)), can be used for the analysis of astrophysical sources of chameleons, proposed by C. Burrage et al. (Phys. Rev. D79, 044028 (2009)), A.-Ch. Davis et al. (Phys. Rev. D80, 064016 (2009), and in references therein, where chameleons induce photons because of direct chameleon-photon transitions in the magnetic fields.Ivanov, A NWellenzohn, MFri, 24 Apr 2015 05:46:28 GMT22 Apr 2015arXiv:1504.05818https://cds.cern.ch/record/2011792Stochastic Background of Gravitational Waves Generated by Compact Binary Systems
https://cds.cern.ch/record/2011771
Binary Systems are the most studied sources of gravitational waves. The mechanisms of emission and the behavior of the orbital parameters are well known and can be written in analytic form in several cases. Besides, the strongest indication of the existence of gravitational waves has arisen from the observation of binary systems. On the other hand, when the detection of gravitational radiation becomes a reality, one of the observed pattern of the signals will be probably of stochastic background nature, which are characterized by a superposition of signals emitted by many sources around the universe. Our aim here is to develop an alternative method of calculating such backgrounds emitted by cosmological compact binary systems during their periodic or quasiperiodic phases. We use an analogy with a problem of Statistical Mechanics in order to perform this sum as well as taking into account the temporal variation of the orbital parameters of the systems. Such a kind of background is of particular importance since it could well form an important foreground for the planned gravitational wave interferometers DECI-Hertz Interferometer Gravitational wave Observatory (DECIGO), Big Bang Observer (BBO), Laser Interferometer Space Antenna (LISA) or Evolved LISA (eLISA), Advanced Laser Interferometer Gravitational-Wave Observatory (ALIGO) and Einstein Telescope (ET).Evangelista, E F Dde Araujo, J C NFri, 24 Apr 2015 05:45:15 GMT23 Apr 2015arXiv:1504.06209https://cds.cern.ch/record/2011771Ices in the Galactic Centre : solid ice and gaseous CO in the central parsec
https://cds.cern.ch/record/2011763
For the past few years, we have observed the central half parsec of our Galaxy in the mid-infrared from 2.8 to 5.1 micron. Our aim is to improve our understanding of the direct environment of SgrA*, the supermassive blackhole at the centre of the Milky Way. This work is described in the present paper and by Moultaka et al. 2015 (submitted). Here, we focus on the study of the spatial distribution of the 12CO ice and gas-phase absorptions. We observed the central half parsec with ISAAC spectrograph located at the UT3/VLT ESO telescope in Chile. The slit was placed along 22 positions arranged parallel to each other to map the region. We built the first data cube in this wavelength range covering the central half parsec. The wavelength interval of the used M-band filter ranges from 4.6 to 5.1 micron. It hosts the P- and R- branches of the ro-vibrational transitions of the gaseous 12CO and 13CO, as well as the absorption band attributed to the 12CO ice at 4.675 micron. Using two calibrators, we could disentangle the local from the line-of-sight absorptions and provide a first-order estimate of the foreground extinction. We find residual ices and gase-phase CO that can be attributed to local absorptions due to material from the interstellar and/or the circumstellar medium of the central parsec. Our finding implies temperatures of the order of 10 to 60K which is in agreement with the presence of water ices in the region highlighted by Moultaka et al. (2004, 2005).Moultaka, JihaneEckart, AndreasSabha, NadeenFri, 24 Apr 2015 05:45:14 GMT23 Apr 2015arXiv:1504.06162https://cds.cern.ch/record/2011763Comparative Analysis of Dayside Reconnection Models in Global Magnetosphere Simulations
https://cds.cern.ch/record/2011761
We test and compare a number of existing models predicting the location of magnetic reconnection at Earth's dayside magnetopause for various solar wind conditions. We employ robust image processing techniques to determine the locations where each model predicts reconnection to occur. The predictions are then compared to the magnetic separators, the magnetic field lines separating different magnetic topologies. The predictions are tested in distinct high-resolution simulations with interplanetary magnetic field (IMF) clock angles ranging from 30 to 165 degrees in global magnetohydrodynamic simulations using the three-dimensional Block-Adaptive Tree Solarwind Roe-type Upwind Scheme (BATS-R-US) code with a uniform resistivity, although the described techniques can be generally applied to any self-consistent magnetosphere code. Additional simulations are carried out to test location model dependence on IMF strength and dipole tilt. We find that most of the models match large portions of the magnetic separators when the IMF has a southward component, with the models saying reconnection occurs where the local reconnection rate and reconnection outflow speed are maximized performing best. When the IMF has a northward component, none of the models tested faithfully map the entire magnetic separator, but the maximum magnetic shear model is the best at mapping the separator in the cusp region where reconnection has been observed. Predictions for some models with northward IMF orientations improve after accounting for plasma flow shear parallel to the reconnecting components of the magnetic fields. Implications for observations are discussed.Komar, C MFermo, R LCassak, P AFri, 24 Apr 2015 05:45:14 GMT23 Apr 2015arXiv:1504.06140https://cds.cern.ch/record/2011761OGLE-IV: Fourth Phase of the Optical Gravitational Lensing Experiment
https://cds.cern.ch/record/2011737
We present both the technical overview and main science drivers of the fourth phase of the Optical Gravitational Lensing Experiment (hereafter OGLE-IV). OGLE-IV is currently one of the largest sky variability surveys worldwide, targeting the densest stellar regions of the sky. The survey covers over 3000 square degrees in the sky and monitors regularly over a billion sources. The main targets include the inner Galactic Bulge and the Magellanic System. Their photometry spans the range of $12<I<21$ mag and $13<I<21.7$ mag, respectively. Supplementary shallower Galaxy Variability Survey covers the extended Galactic bulge and 2/3 of the whole Galactic disk within the magnitude range of $10<I<19$ mag. All OGLE-IV surveys provide photometry with milli-magnitude accuracy at the bright end. The cadence of observations varies from 19-60 minutes in the inner Galactic bulge to 1-3 days in the remaining Galactic bulge fields, Magellanic System and the Galactic disk. OGLE-IV provides the astronomical community with a number of real time services. The Early Warning System (EWS) contains information on two thousand gravitational microlensing events being discovered in real time annually, the OGLE Transient Detection System (OTDS) delivers over 200 supernovae a year. We also provide the real time photometry of unpredictable variables such as optical counterparts to the X-ray sources and R CrB stars. Hundreds of thousands new variable stars have already been discovered and classified by the OGLE survey. The number of new detections will be at least doubled during the current OGLE-IV phase. The survey was designed and optimized primarily to conduct the second generation microlensing survey for exoplanets. It has already contributed significantly to the increase of the discovery rate of microlensing exoplanets and free-floating planets.Udalski, ASzymański, M KSzymański, GFri, 24 Apr 2015 05:45:11 GMT22 Apr 2015arXiv:1504.05966https://cds.cern.ch/record/2011737Evidence for a spectroscopic direct detection of reflected light from 51 Peg b
https://cds.cern.ch/record/2011734
The detection of reflected light from an exoplanet is a difficult technical challenge at optical wavelengths. Even though this signal is expected to replicate the stellar signal, not only is it several orders of magnitude fainter, but it is also hidden among the stellar noise. We apply a variant of the cross-correlation technique to HARPS observations of 51 Peg to detect the reflected signal from planet 51 Peg b. Our method makes use of the cross-correlation function of a binary mask with high-resolution spectra to amplify the minute planetary signal that is present in the spectra by a factor proportional to the number of spectral lines when performing the cross correlation. The resulting cross-correlation functions are then normalized by a stellar template to remove the stellar signal. Carefully selected sections of the resulting normalized CCFs are stacked to increase the planetary signal further. The recovered signal allows probing several of the planetary properties, including its real mass and albedo. We detect evidence for the reflected signal from planet 51 Peg b at a significance of 3\sigma_noise. The detection of the signal permits us to infer a real mass of 0.46^+0.06_-0.01 M_Jup (assuming a stellar mass of 1.04\;M_Sun) for the planet and an orbital inclination of 80^+10_-19 degrees. The analysis of the data also allows us to infer a tentative value for the (radius-dependent) geometric albedo of the planet. The results suggest that 51Peg b may be an inflated hot Jupiter with a high albedo (e.g., an albedo of 0.5 yields a radius of 1.9 \pm 0.3 R_Jup for a signal amplitude of 6.0\pm0.4 x 10^-5). We confirm that the method we perfected can be used to retrieve an exoplanet's reflected signal, even with current observing facilities. The advent of next generation of observing facilities will yield new opportunities for this type of technique to probe deeper into exoplanets.Martins, J H CSantos, N CFigueira, PFaria, J PMontalto, MBoisse, IEhrenreich, DLovis, CMayor, MMelo, CPepe, FSousa, S GUdry, SCunha, DFri, 24 Apr 2015 05:45:11 GMT22 Apr 2015arXiv:1504.05962https://cds.cern.ch/record/2011734A Taste of Cosmology
https://cds.cern.ch/record/2011726
This is the summary of two lectures that aim to give an overview of cosmology. I will not try to be too rigorous in derivations, nor to give a full historical overview. The idea is to provide a "taste" of cosmology and some of the interesting topics it covers. The standard cosmological model is presented and I highlight the successes of cosmology over the past decade or so. Keys to the development of the standard cosmological model are observations of the cosmic microwave background and of large-scale structure, which are introduced. Inflation and dark energy and the outlook for the future are also discussed. Slides from the lectures are available from the school website: physicschool.web.cern.ch/PhysicSchool/CLASHEP/CLASHEP2011/.Verde, LFri, 24 Apr 2015 05:45:10 GMT22 Apr 2015arXiv:1504.05945https://cds.cern.ch/record/2011726Free the Globe
https://cds.cern.ch/record/2011721
The parallel globe is an old, very simple and ingenious device that, when systematically employed in astronomy classes, becomes a teaching tool with great potential. Properly oriented according to the local meridian, this instrument allows us to follow the shadows in any region of the Earth that is illuminated by the Sun, as well as offering a clear view of the terminator, the fast-moving grey line that divides the day from the night on our planet. With knowledge of the shadows, it is possible to estimate the latitude of a site and to infer local solar time anywhere in the planet's sunlit hemisphere. Furthermore, by using the parallel globe we may understand simply the existence of regions in which objects sometimes do not cast shadows, and also other regions which, on the contrary, sometimes become "long-shadow" countries. In this work, we first review the device and the basics of its assembly and operation. In the second part, we describe in detail some activities targeted to facilitate its use in the classroom, which our research group has been developing during teacher training workshops.Gangui, AlejandroFri, 24 Apr 2015 05:45:09 GMT22 Apr 2015arXiv:1504.05918https://cds.cern.ch/record/2011721High-Order Kinetic Relaxation Schemes as High-Accuracy Poisson Solvers
https://cds.cern.ch/record/2011711
We present a new approach to find accurate solutions to the Poisson equation, as obtained from the steady-state limit of a diffusion equation with strong source terms. For this purpose, we start from Boltzmann's kinetic theory and investigate the influence of higher order terms on the resulting macroscopic equations. By performing an appropriate expansion of the equilibrium distribution, we provide a method to remove the unnecessary terms up to a desired order and show that it is possible to find, with high level of accuracy, the steady-state solution of the diffusion equation for sizeable Knudsen numbers. In order to test our kinetic approach, we discretise the Boltzmann equation and solve the Poisson equation, spending up to six order of magnitude less computational time for a given precision than standard lattice Boltzmann methods.Mendoza, MSucci, SHerrmann, H JFri, 24 Apr 2015 05:45:07 GMT22 Apr 2015arXiv:1504.05869https://cds.cern.ch/record/2011711Editorial for the Special Issue 100 Years of Chronogeometrodynamics: The Status of the Einstein's Theory of Gravitation in Its Centennial Year
https://cds.cern.ch/record/2011704
The present Editorial introduces the Special Issue dedicated by the journal Universe to the General Theory of Relativity, the beautiful theory of gravitation of Einstein, a century after its birth. It reviews some of its key features in a historical perspective, and, in welcoming distinguished researchers from all over the world to contribute it, some of the main topics at the forefront of the current research are outlined.Iorio, LorenzoFri, 24 Apr 2015 05:45:06 GMT21 Apr 2015arXiv:1504.05789https://cds.cern.ch/record/2011704Improving the Quality of FORS2 Reduced Spectra
https://cds.cern.ch/record/2011690
The FORS2 instrument is one of the most widely used and productive instruments on the Very Large Telescope. This article reports on a project to improve the quality of the reduced FORS2 spectra that can be produced with the software provided by ESO. The result of this effort is that spectra of significantly higher quality can now be produced with substantially lower effort by the science user of the data.Moehler, SabineDabo, C E GarcíaBoffin, HenriRupprecht, GeroSaviane, IvoFreudling, WolframFri, 24 Apr 2015 05:45:04 GMT22 Apr 2015arXiv:1504.05683https://cds.cern.ch/record/2011690Design of a neutrino source based on beta beams
https://cds.cern.ch/record/2011661
``Beta beams'' produce collimated pure electron (anti)neutrino beams by accelerating beta active ions to high energies and having them decay in a racetrack shaped storage ring of 7 km circumference, the decay ring. EUROnu beta beams are based on CERN infrastructures and existing machines. Using existing machines may be an advantage for the cost evaluation, but will also constrain the physics performance. The isotope pair of choice for the beta beam is $^{6}\mathrm{He}$ and $^{18}\mathrm{Ne}$. However, before the EUROnu studies one of the required isotopes, $^{18}\mathrm{Ne}$, could not be produced in rates that satisfy the needs for physics of the beta beam. Therefore, studies of alternative beta emitters, $^{8}\mathrm{Li}$ and $^{8}\mathrm{B}$, with properties interesting for a beta beam have been proposed and have been studied within EUROnu. These alternative isotopes could be produced by using a small storage ring, in which the beam traverses a target, creating the $^{8}\mathrm{Li}$ and $^{8}\mathrm{B}$ isotopes. This production ring, the injection linac and the target system have been evaluated. Measurements of the cross section of the reactions to produce the beta beam isotopes show interesting results. A device to collect the produced isotopes from the target has been developed and tested. However, the yields of $^{8}\mathrm{Li}$ and $^{8}\mathrm{B}$, using the production ring for production of $^{8}\mathrm{Li}$ and $^{8}\mathrm{B}$, is not yet, according to simulations, giving the rates of isotopes that would be needed. Therefore, a new method of producing the $^{18}\mathrm{Ne}$ isotope has been developed and tested giving good production rates. A 60 GHz ECRIS prototype, the first in the world, was developed and tested for ion production with contributions from EUROnu. The decay ring lattices for the $^{8}\mathrm{Li}$ and $^{8}\mathrm{B}$ have been developed and the lattice for $^{6}\mathrm{He}$ and $^{18}\mathrm{Ne}$ has been optimized to ensure the high intensity ion beam stability.Wildner, EHansen, CBenedetto, EJensen, EStora, TMendonca, T MeloVlachoudis, VBouquerel, EMarie-Jeanne, MBalint, PFourel, CGiraud, JJacob, JLamy, TLatrasse, LSortais, PThuillier, TMitrofanov, SLoiselet, MKeutgen, ThDelbar, ThDebray, FTrophime, CVeys, SDaversin, CZorin, VIzotov, ISkalyga, VChancé, APayet, JBurt, GDexter, A CKravchuk, V LMarchi, TCinausero, MGramegna, FAngelis, G DePrete, GCollazuol, GMezzetto, MVardaci, ENitto, A DiBrondi, ARana, G LaMoro, RPalladino, VGelli, NMazzocco, MSignorini, CHirsh, T YHass, MBerkovits, DStahl, ASchaumann, MWehner, JFri, 24 Apr 2015 04:02:38 GMT2014-07https://cds.cern.ch/record/2011661A New RadMon Version for the LHC and its Injection Lines
https://cds.cern.ch/record/2011660
A system to monitor the radiation levels is required in the Large Hadron Collider (LHC) and its injection lines in order to quantify the radiation effects on electronics. Thus, the RadMons were installed in critical areas where equipment is or will be placed. The first years of operation, successive test campaigns and new requirements, raised the need for a new design of the monitor. The architecture of the new RadMon, the radiation reliability and the design strategy adopted for the sensors, used for monitoring the mixed radiation field of the LHC accelerator, are described highlighting the achieved improvements in terms of radiation robustness and measurement accuracy of a device which is of interest for many other research institutes.Spiezia, GPeronnard, PMasi, ABrugger, MBrucoli, MDanzeca, SGarcia Alia, RLosito, RMekki, JOser, PGaillard, RDusseau, LFri, 24 Apr 2015 04:02:38 GMThttps://cds.cern.ch/record/2011660Heavy-flavour correlations in pp, p–Pb and Pb–Pb collisions
https://cds.cern.ch/record/2011659
Heavy quarks (charm and beauty) are produced in initial hard scattering processes in heavy-ion collisions, before the formation of a strongly interacting medium, the Quark Gluon Plasma. Insight into the effects of the medium on charm and beauty production can be obtained by measuring the angular correlations between open heavy-flavour hadrons and charged particles. In Pb–Pb collisions, the azimuthal correlation can provide information on the way heavy quarks lose energy in the QGP and is sensitive to possible modifications of the charm parton shower and hadronisation in the presence of the medium. The observed double-ridge long-range correlations in p–Pb collisions for light-flavour hadrons could originate from a collective expansion of the system, as well as from gluon saturation in the initial state (colour glass condensate). The same effect can be studied for heavier quarks via the correlation between heavy-flavour hadrons (or their decay electrons) and charged particles.Bjelogrlić, SandroFri, 24 Apr 2015 04:02:37 GMThttps://cds.cern.ch/record/2011659Heavy-flavour elliptic flow measured in Pb–Pb collisions at $\sqrt {s_{NN}}=2.76$ TeV with ALICE
https://cds.cern.ch/record/2011658
The ALICE Collaboration has measured the production of open heavy-flavour hadrons relative to the reaction plane in Pb–Pb collisions at sNN=2.76 TeV . The anisotropy is quantified in terms of the second harmonic, the elliptic flow v2 , in the Fourier expansion of the particle azimuthal distribution. The v2 measurements are presented for prompt charm mesons, i.e. D 0 , D + , D ⁎+ , and heavy-flavour decay electrons at mid-rapidity, as well as for heavy-flavour decay muons at forward rapidity for various centrality intervals. The results are compared with the ones for charged particles and with model calculations of charm and beauty quark transport and energy loss in high-density strongly-interacting matter at high temperature.Bailhache, RaphaelleFri, 24 Apr 2015 04:02:37 GMThttps://cds.cern.ch/record/2011658