WorldWideScience

Sample records for luminosity factor

  1. Quality Factor for the Hadronic Calorimeter in High Luminosity Conditions

    CERN Document Server

    Balabram, LE; The ATLAS collaboration; Filho, LM

    2014-01-01

    The Tile Calorimeter (TileCal) is the central section of the hadronic calorimeter of ATLAS experiment and has about 10,000 eletronic channels. An Optimal Filter (OF) has been used to estimate the energy sampled by the calorimeter and applies a Quality Factor (QF) for signal acceptance. An approach using Matched Filter (MF) has also been pursued. In order to cope with the luminosity rising foreseen for LHC operation upgrade, different algorithms have been developed. Among them, the Constrained Optimal Filter (COF) is showing good capacity in handling such luminosity rise by using a deconvolution technique, which revocers physics signals from out of time pile up. When pile up noise is low, COF switches to MF estimator for optimal performance. Currently, the OF measure for signal acceptance is implemented through a chi-square test. At a low-muninosity scenario, such QF measure has been used as a way to describe how the acquired singal is compatible to the pulse shape pattern. However, at high-luminosity conditio...

  2. Low Luminosity Gamma-Ray Bursts as a Unique Population: Luminosity Function, Local Rate, and Beaming Factor

    CERN Document Server

    Liang, E; Dai, Z G; Liang, Enwei; Zhang, Bing

    2006-01-01

    The newly discovered GRB 060218 is a nearby event with low luminosity, resembling GRBs 980425 and 031203. The fact that it was discovered by Swift slightly over 1-year operation suggests that the GRB rate of these low luminosity GRBs (LL-GRBs) should be much higher than previous expected, and that they form a distinct new class of GRBs with respect to the conventional high luminosity GRBs (HL-GRBs). We characterize the LF of each class by a smoothed broken power law, $\\Phi(L)\\propto [(L/L_b)^{\\alpha_1}+(L/L_b)^{\\alpha_2}]^{-1}$, and investigate the constraints to the LF parameters by the following two criteria: (1) The absolute GRB numbers predicted by the LFs for both LL-GRBs and HL-GRBs should be consistent with the Swift detections for the two classes, respectively; and (2) at 3 sigma significance level, the 2-dimensional GRB distributions in the luminosity-redshift plane derived from the LFs should be consistent with the data of GRBs with known redshifts detected by Swift and other missions. We obtain alp...

  3. Ruling factors in the impact of collision debris on the LHC high luminosity insertion magnets

    International Nuclear Information System (INIS)

    The Large Hadron Collider built at CERN now enters a starting-up phase in order to reach the present design luminosity (L0) of 1034 cm-2s-1. A possible upgrade of the machine to a luminosity value of 10L0 requires a new design of some insertion region magnets, and will be implemented in essentially two phases. The energy from collision debris is deposited in the insertion region magnetic elements and in particular in the superconducting magnet coils with a possible risk of quench. The role of the key parameters (such as the magnet aperture, the crossing plane, the thickness of a possible shielding liner, . . .) is pointed out, in order to optimize the design of the new insertion regions for the Upgrade phase I aiming to reach 2 - 3 L0. (author)

  4. The CO luminosity and CO-H2 conversion factor of diffuse ISM: does CO emission trace dense molecular gas?

    OpenAIRE

    Liszt, Harvey,; Pety, Jerome; LUCAS, Robert

    2010-01-01

    Aims: We wish to separate and quantify the CO luminosity and CO-H2 conversion factor applicable to diffuse but partially-molecular ISM when H2 and CO are present but C+ is the dominant form of gas-phase carbon. Methods: We discuss galactic lines of sight observed in \\HI, HCO+ and CO where CO emission is present but the intervening clouds are diffuse (locally \\AV\\ $\\la 1$ mag) with relatively small CO column densities $\\NCO \\la 2\\times10^{16}\\pcc$. We separate the atomic and molecular fraction...

  5. The CO luminosity and CO-H2 conversion factor of diffuse ISM: does CO emission trace dense molecular gas?

    CERN Document Server

    Liszt, Harvey; Lucas, Robert

    2010-01-01

    Aims: We wish to separate and quantify the CO luminosity and CO-H2 conversion factor applicable to diffuse but partially-molecular ISM when H2 and CO are present but C+ is the dominant form of gas-phase carbon. Methods: We discuss galactic lines of sight observed in \\HI, HCO+ and CO where CO emission is present but the intervening clouds are diffuse (locally \\AV\\ $\\la 1$ mag) with relatively small CO column densities $\\NCO \\la 2\\times10^{16}\\pcc$. We separate the atomic and molecular fractions statistically using \\EBV\\ as a gauge of the total gas column density and compare NH2 to the observed CO brightness. Results: Although there are H2-bearing regions where CO emission is too faint to be detected, the mean ratio of integrated CO brightness to NH2 for diffuse ISM does not differ from the usual value of 1\\K km/s of integrated CO brightness per $2\\times10^{20}$ H2 $\\pcc$ . Moreover, the luminosity of diffuse CO viewed perpendicular to the galactic plane is 2/3 that seen at the Solar galactic radius in surveys ...

  6. Light, Luminosity and the High Luminosity LHC

    CERN Multimedia

    2015-01-01

    Short interview to Lucio Rossi, project leader of the High Luminosity LHC, about the concept of light in physics, light and luminosity in particle accelerators and the High Luminosity LHC project. On the occasion of International Year of Light 2015.

  7. High-luminosity considerations

    International Nuclear Information System (INIS)

    There appears to be some controversy over how high a luminosity one can use before a variety of detector limitations impose a practical limit. Factors leading to flux limitations for a variety of detector types are discussed, and practical considerations to extending those limits are reviewed. Also, a method of reducing the effects of pileup inherent in calorimeter use at L = 1033/cm2/sec is given

  8. ISR Superconducting High luminosity Insertion

    CERN Multimedia

    1981-01-01

    The picture shows two of the eight superconducting quadrupoles of the low-beta insertion at intersection I8.The increase of luminosity produced by this insertion was above a factor 7. At right one can also see the Open- Axial- Field Magnet. The person is Stephan Pichler. See also 7702690X, 8102123, 8010397, 8008332.

  9. Dijet spectroscopy at high luminosity

    International Nuclear Information System (INIS)

    A study of the dijet mass resolution has been made appropriate to high luminosity operation. As a benchmark, the mass resolution of W ? jj for a Higgs boson of 800 GeV has been optimized for no, eight, and sixteen overlapping minbias events. A factor of 2.5 degradation in Mjj width is seen. 6 refs., 10 figs

  10. Satellite Luminosities in Galaxy Groups

    OpenAIRE

    Skibba, Ramin A.; Sheth, Ravi K.; Martino, Matthew C.

    2007-01-01

    Halo model interpretations of the luminosity dependence of galaxy clustering assume that there is a central galaxy in every sufficiently massive halo, and that this central galaxy is very different from all the others in the halo. The halo model decomposition makes the remarkable prediction that the mean luminosity of the non-central galaxies in a halo should be almost independent of halo mass: the predicted increase is about 20% while the halo mass increases by a factor of more than 20. In c...

  11. Luminosity measurement at AMY

    International Nuclear Information System (INIS)

    We describe a luminosity measurement at AMY in this report. A luminosity is measured by counting Bhabha events by calorimeters situated at forward and backward region of the AMY detector. A position of charged particles are measured by resistive tube chambers between a front and a rear calorimeters as well as a energy of the particles by the ESC. The systematic error of the luminosity measurements is estimated to be 1.8% in total. The largest contributions for that are uncertainty of an alignment of the detector and a higher order effect for calculation of a Bhabha scattering cross section. The luminosity is measured by a barrel calorimeter too. The results of the luminosity are consistent with each other within a error. (author)

  12. Luminosity Function of GRBs

    CERN Document Server

    Sethi, S; Sethi, Shiv

    2001-01-01

    We attempt to constrain the luminosity function of Gamma Ray Bursts (GRBs) from the observed number count--flux relation and the afterglow redshift data. We assume three classes of luminosity functions for our analysis: (a) Log-normal distribution, (b) Schechter distribution, and (c) Scale-free distribution. We assume several models of the evolution of the GRB population for each luminosity function. Our analysis shows that: (a) log-normal is the only luminosity function that is compatible with both the observations. This result is independent of the GRB evolution model, (b) for log-normal function, the average photon luminosity $L_0$ and the width of the luminosity function $\\sigma$ that are compatible with both the observations fall in the range: $10^{55} sec^{-1} \\la L_0 \\la 10^{56} sec^{-1}$ and $2 \\la \\sigma \\la 3$, (c) the agreement of observations with other luminosity functions requires the GRB population to evolve more strongly than the evolution of the star-formation rate of the universe.

  13. Luminosity measurement at AMY

    International Nuclear Information System (INIS)

    A precise measurement of a luminosity is required by experiments with high statistics. The largest sources of a systematic error of a luminosity measurement are an alignment of the tube chambers which measure a polar angle of Bhabha events and a higher order correction for the Bhabha cross section calculation. We describe a resent study for these uncertainties and how to reduce the systematic errors from these sources. The total systematic error of the luminosity measurement of 1.8% can be reduced to 1.0% by this study. (author)

  14. A Luminosity Calorimeter for CLIC

    CERN Document Server

    Abramowicz, H; Kananov, S; Levy, A; Sadeh, I

    2009-01-01

    For the relative precision of the luminosity measurement at CLIC, a preliminary target value of 1% is being assumed. This may be accomplished by constructing a finely granulated calorimeter, which will measure Bhabha scattering at small angles. In order to achieve the design goal, the geometrical parameters of the calorimeter need to be defined. Several factors influence the design of the calorimeter; chief among these is the need to minimize the error on the luminosity measurement while avoiding the intense beam background at small angles. In this study the geometrical parameters are optimized for the best performance of the calorimeter. In addition, the suppression of physics background to Bhabha scattering is investigated and a set of selection cuts is introduced.

  15. Luminosity Studies in ATLAS

    CERN Document Server

    Are Sivertsen, Traeet

    2015-01-01

    During the course of this summer I've been tasked with many dierent assignments working with the ATLAS Luminosity Taskforce. My main project was related to updating a PyROOT script that in Run1 was responsible for making comparison plots of the measured luminosity of subsystem detectors at ATLAS, and making it compatible with the new les used to store the data. The main purpose of this script was to enable an easy method for which one could get a quick overview of the measured luminosity over many runs such that one could see the stability of the subsystem detectors. This is useful to determine if there is any issues with the detectors so that one could investigate it further. The comparison plots can now be seen on the 2015 Run Data Preparation webpage.

  16. Luminosity enhancements at SLAC

    International Nuclear Information System (INIS)

    Several ideas are discussed that have been proposed to improve the luminosity at the SPEAR and PEP electron-positron storage rings and to insure good luminosity at the SLAC Linear Collider. There have been two proposals studied recently for SPEAR: a Microbeta insertion using Samarium Cobalt permanent magnets, and a Minibeta insertion using conventional quadrupole magnets. The notations Microbeta and minibeta used here are somewhat arbitrary since the front faces of the first quadrupole magnets for both insertions are at nearly the same distance from the interaction point

  17. High luminosity particle colliders

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, R.B.; Gallardo, J.C. [Brookhaven National Lab., Upton, NY (United States). Center for Accelerator Physics

    1997-03-01

    The authors consider the high energy physics advantages, disadvantages and luminosity requirements of hadron (pp, p{anti p}), lepton (e{sup +}e{sup {minus}}, {mu}{sup +}{mu}{sup {minus}}) and photon-photon colliders. Technical problems in obtaining increased energy in each type of machine are presented. The machines relative size are also discussed.

  18. High luminosity particle colliders

    International Nuclear Information System (INIS)

    The authors consider the high energy physics advantages, disadvantages and luminosity requirements of hadron (pp, p anti p), lepton (e+e-, μ+μ-) and photon-photon colliders. Technical problems in obtaining increased energy in each type of machine are presented. The machines relative size are also discussed

  19. An Anthropology of Luminosity

    DEFF Research Database (Denmark)

    Bille, Mikkel; Sørensen, Tim Flohr

    2007-01-01

    luminosity in the practice of day-to-day activities. The article surveys an array of past conceptions of light within philosophy, natural science and more recent approaches to light in the fields of anthropology and material culture studies. A number of implications are discussed, and by way of three case...

  20. The MICE luminosity monitor

    Science.gov (United States)

    Dobbs, A.; Forrest, D.; Soler, F. J. P.

    2013-02-01

    The MICE experiment will provide the first measurement of ionisation cooling, a technique suitable for reducing the transverse emittance of a tertiary muon beam in a future neutrino factory accelerator facility. MICE is presently in the final stages of commissioning its beam line. The MICE luminosity monitor has proved an invaluable tool throughout this process, providing independent measurements of particle rate from the MICE target, normalisation for beam line detectors and verification of simulation codes.

  1. A luminosity model of RHIC gold runs

    International Nuclear Information System (INIS)

    In this note, we present a luminosity model for RHIC gold runs. The model is applied to the physics fills in 2007 run without cooling, and with the longitudinal cooling applied to one beam only. Having good comparison, the model is used to project a fill with the longitudinal cooling applied to both beams. Further development and possible applications of the model are discussed. To maximize the integrated luminosity, usually the higher beam intensity, smaller longitudinal and transverse emittance, and smaller β are the directions to work on. In past 10 years, the RHIC gold runs have demonstrated a path toward this goal. Most recently, a successful commissioning of the bunched beam stochastic cooling, both longitudinal and transverse, has offered a chance of further RHIC luminosity improvement. With so many factors involved, a luminosity model would be useful to identify and project gains in the machine development. In this article, a preliminary model is proposed. In Section 2, several secondary factors, which are not yet included in the model, are identified based on the RHIC operation condition and experience in current runs. In Section 3, the RHIC beam store parameters used in the model are listed, and validated. In Section 4, the factors included in the model are discussed, and the luminosity model is presented. In Section 5, typical RHIC gold fills without cooling, and with partial cooling are used for comparison with the model. Then a projection of fills with more coolings is shown. In Section 6, further development of the model is discussed.

  2. To High Luminosity and beyond!

    CERN Multimedia

    CERN Bulletin

    2015-01-01

    This week marks a major milestone for the High Luminosity LHC (HL-LHC - see here) project, as it moves from the design study to the machine construction phase. HL-LHC will extend the LHC’s discovery potential, increasing luminosity by a factor of 10 beyond the original design value and allowing the scientific community to study new phenomena.    Composer Domenico Vicinanza (left) directs the musical performance of sonified LHC data during a special Hi-Lumi event (see box). The green light was given during the 5th Joint HiLumi LHC-LARP annual meeting that took place at CERN from 26 to 30 October 2015. The meeting saw the participation of more than 230 experts from all over the world to discuss the results and achievements of the HiLumi LHC Design Study. During the week, these experts approved the first version of the HL-LHC Technical Design Report – the document that, following the Preliminary Design Report issued in 2014, describes in detail how the LHC upgrade progra...

  3. SLHC: The LHC luminosity upgrade

    International Nuclear Information System (INIS)

    The LHC will provide unprecedented sensitivity to Standard Model and beyond the Standard Model Physics. However, some important Standard Model measurements as well as a wide part of the spectrum of particles predicted by many promising theoretical models of New Physics are likely beyond the LHC reach. For such observations, a factor-of-ten increase in LHC statistics will have a major impact. A luminosity upgrade is therefore planned for the LHC. The SLHC as well as offering the possibility to increase the Physics potential will create an extreme operating environment for the detectors, particularly the tracking devices. An increase in the number of minimum bias events per beam crossing by at least an order of magnitude beyond the levels envisioned for LHC design luminosity creates the need to handle much higher occupancies and for the innermost layers unprecedented levels of radiation. This will require a fully upgraded tracking system giving a higher granularity, while trying not to exceed the material budget and power levels of the current trackers. The much higher rate of interactions may also push the limits of the Level-1 trigger system. Efforts have already begun to address these issues. This paper presents the possible Physics reaches at SLHC and the current understanding of what systems will need to be upgraded.

  4. Luminosity upgrades on PEP

    International Nuclear Information System (INIS)

    Over the past two years the authors have explored several ideas for Luminosity Upgrades on PEP. This followed the recommendation of the Goldhaber Committee which concluded that unless PETRA uncovered new physics at higher energies then PEP should concentrate on higher luminosity at its present energy. These studies explored many schemes which involved lowering the ? functions (stronger focussing) at the interaction points, as it has been employed at CESR, PETRA, DORIS II and in PEP. The first round of studies assumed that all six interaction regions would be required and that the overall chromatic aberrations which could be tolerated and corrected should not exceed their present value. This led to designs which incorporated quadrupoles for the low-? insertions which were placed inside the magnetic field region of the detectors. Because of the high fields in some of the detectors, these quadrupoles would have to be either superconducting iron-free, or permanent magnet (samarium-cobalt) designs. Although machine lattice designs were readily achievable using these techniques, the engineering complexity and the impact on detectors made these schemes rather unattractive. This forced a review of the above assumptions and led to the studies of the Mini-Maxi Beta and the Six-Fold Mini Beta schemes described in this paper. 2 figures, 1 table

  5. Flare colours and luminosities

    International Nuclear Information System (INIS)

    Flare colours determined from simultaneous UBV observations made at Catania Observatory and from sequential UBV observations made at McDonald Observatory are presented. They fit fairly well with the theoretical colours computed according to the Gurzadian's (1970) non-thermal model. Only part of the observed flare colours are consistent with the solar type models by Gershberg (1967) and Kunkel (1970). From a B-band patrol of UV Cet-type stars carried out from 1967 to 1972, some quantitative estimates of flare frequencies and luminosities and their average contributions to the stellar radiation are given. The corresponding parameters for the Sun, which were estimated from 'white light' flare activity, are also given for comparison. The Sun and V 1216 Sgr can be regarded as low-activity flare stars of the type found by Kunkel (1973). (Auth.)

  6. HIGHER LUMINOSITY B-FACTORIES

    International Nuclear Information System (INIS)

    The present B-factories PEP-II and KEKB have reached luminosities of 3-4 x 1033/cm2/s and delivered integrated luminosity at rates in excess of 4fb-1 per month [1,2]. The recent turn on of these two B-Factories has shown that modern accelerator physics, design, and engineering can produce colliders that rapidly reach their design luminosities and deliver integrated luminosities capable of frontier particle physics discoveries. PEP-II and KEK-B with ongoing upgrade programs should reach luminosities of over 1034/cm2/s in a few years and with more aggressive improvements may reach luminosities of order 1035/cm2/s by the end of the decade. However, due to particle physics requirements, the next generation B-Factory may require significantly more luminosity. Initial parameters of a very high luminosity e+e- B-Factory or Super B-Factory (SBF) are being developed incorporating several new ideas from the successful operation of the present generation e+e-accelerators [3,4]. A luminosity approaching 1036 cm-2s-1 appears possible. Furthermore, the ratio of average to peak luminosity may be increased by 30% due to continuous injection. The operation of this accelerator will be qualitatively different from present e+e- colliders due to this continuous injection

  7. Different Luminosity Correlation of GRBs

    Indian Academy of Sciences (India)

    Z. B. Zhang; H. C. Liu; L. Y. Jiang; D. Y. Chen

    2014-09-01

    We report our recent understanding about a tight correlation between relative spectral lag and luminosity (or redshift) for -ray bursts. The latest investigations indicate that the empirical correlations got from BATSE bursts also exist for Swift/BAT ones. The special luminosity-lag correlation is much similar to that of the luminosity with pulse number proposed by Schaefer (2003), but largely different from most others ever discovered. Note that our newly built luminosity-lag correlation predicts that luminosity should evolve with cosmological redshift as p ∝ (1 + )2.4 ± 0.7 that is excellently confirmed by Salvaterra et al. (2012) and Geng & Huang (2013). In addition, it is also surprisingly found that the luminosity-lag correlation can account for both long and short Swift/BAT bursts, which might be an evidence of the same radiation mechanism for diverse burst groups.

  8. Luminosity monitor studies for TESLA

    International Nuclear Information System (INIS)

    The feasibility of a luminosity monitor based on a radiative Bhabha detector is investigated n the context of the TESLA linear collider. Another option based on low energy e+e- pair calorimetry is also discussed. In order to monitor the beam parameters at the interaction point by optimizing the luminosity, these detectors should be able to provide a relative measurement of the luminosity with a resolution better that 1% using a fraction of the TESLA bunch train. (author)

  9. Luminosity of type I supernovae

    International Nuclear Information System (INIS)

    We have recalculated the luminosity of type I supernovae by using (1) the diffusive release of Ni56 decay energy (Colgate and McKee), (2) the progressive gamma-ray transparency as calculated by a Monte Carlo gamma-ray simulation code, and (3) the fractional deposition of positrons (ARnett). If we take 100% optical fluorescence efficiency (Meyerott) and choose a nebula that is expanding uniformly and at constant velocity such that it is one ?-ray mean free path (35.5 g cm-2) thick at 20 days, we obtain excellent agreement with observations. Three independent physical phenomena are involved. The first is the diffusive release of thermal radiation that with the 6.1 day Ni56 decay determines the height and width of the optical peak. The second is the initial fast decay of the optical peak by a factor of roughly 100 as determined by the progressive transparency to ?-rays. The third is the apparent 56 day half-life that results from the progressive escape of the positron fraction of the 77 day Co56 decay. To obtain agreement with observations, each of these three independent phenomena requires that the expanding nebula be described by a single relation M/sub ej/ upsilon9-2=0.22 +- 0.05, where M/sub ej/ is the ejected mass in solar masses and upsilon9 is the expansion velocity in units of 109 cm s-1. Total energy requirements exclude the possibility of the ejection of an envelope > or approx. =0.75 M/sub sun/, yet the optical luminosity requires that approx.0.25 M/sub sun/ of the ejected matter be Ni56

  10. High Luminosity LHC (HL-LHC) general infographics

    CERN Document Server

    Landua, Fabienne

    2016-01-01

    The High-Luminosity LHC, which is expected to be operational after 2025, will increase the LHC’s luminosity by a factor of 10. To achieve this major upgrade, several technologies, some of which are completely innovative, are being developed.

  11. Beam Imaging and Luminosity Calibration

    CERN Document Server

    Klute, Markus; Salfeld-Nebgen, Jakob

    2016-01-01

    We discuss a method to reconstruct two-dimensional proton bunch densities using vertex distributions accumulated during LHC beam-beam scans. The $x$-$y$ correlations in the beam shapes are studied and an alternative luminosity calibration technique is introduced. We demonstrate the method on simulated beam-beam scans and estimate the uncertainty on the luminosity calibration associated to the beam-shape reconstruction to be below 1\\%.

  12. Beam Imaging and Luminosity Calibration

    CERN Document Server

    AUTHOR|(CDS)2081126; Klute, Markus; Medlock, Catherine Aiko

    2016-01-01

    We discuss a method to reconstruct two-dimensional proton bunch densities using vertex distributions accumulated during LHC beam-beam scans. The x-y correlations in the beam shapes are studied and an alternative luminosity calibration technique is introduced. We demonstrate the method on simulated beam-beam scans and estimate the uncertainty on the luminosity calibration associated to the beam-shape reconstruction to be below 1%.

  13. The unexpected clustering of the optical afterglow luminosities

    CERN Document Server

    Nardini, M; Ghirlanda, G; Tavecchio, F; Firmani, C; Lazzati, D

    2006-01-01

    We studied the behaviour of the optical afterglow lightcurves of a sample of 24 Gamma--Ray Bursts (GRBs) with known redshift and published estimates of the optical extinction in the source frame, detected before the SWIFT satellite launch. We found an unexpected clustering of the optical luminosities at 12 hours in the source frame. The distribution of the optical luminosities is narrower than the distribution of X-ray luminosities at the same time. Few (3) bursts stand apart from the main optical distribution, being fainter by a factor of about 15. We also analysed the optical luminosities of the SWIFT burst with known redshift finding that the luminosity distribution is similar to the pre SWIFT GRBs one, even if they have a different mean redshift. These results can suggest the existence of a family of intrinsically optically under--luminous dark GRBs.

  14. Recent luminosity improvements at the SLC

    International Nuclear Information System (INIS)

    The luminosity of the SLAC Linear Collider (SLC) has been increased by more than a factor of three during the 1997--98 run. Improved alignment and emittance tuning techniques throughout the accelerator resulted in minimal emittance growth from the damping rings to the final focus. In particular, a revised strategy for wakefield cancellation using precision beam size measurements at the entrance of the final focus proved effective for optimizing emittance. The final focus lattice was modified to provide stronger demagnification near the interaction point and to remove residual higher-order aberrations. Beam sizes as small as 1.5 by 0.65 microns were achieved at full beam intensity of 4 1010 particles per pulse. With these parameters, the mutual focusing of the beams in collision becomes significant, resulting in a further increase in the luminosity. Recorded SLD event rates confirmed the theoretical calculations of the disruption enhancement which was typically 50 to 100%

  15. Luminosity measurement in H1

    International Nuclear Information System (INIS)

    At HERA, luminosity is determined on-line and bunch by bunch by measuring the Bremsstrahlung spectrum from e-p collisions. The Hl collaboration has built a completely new luminosity system in order to sustain the harsh running conditions after the fourfold luminosity increase. Namely, the higher synchrotron radiation doses and the increased event pile-up have governed the design of the two major components, a radiation resistant quartz-fibre electro-magnetic calorimeter, and a fast read-out electronic with on-line energy histogram loading at a rate of 500 kHz. The group was in charge of the electronic and the on-line data analysis of the new luminosity system. In this thesis, I present analysis tools and methods to improve the precision of the luminosity measurement. The energy scale and acceptance calculation methods set out in this thesis permit these values to be determined every four minutes, to an accuracy of 0.5 parts per thousand for the energy scale and 2 parts per thousand for the acceptance. From these results, the degree of accuracy obtained on the luminosity measurement is between 6.5 and 9.5 parts per thousand. These results are currently undergoing validation, with the aim of becoming the standard H1 method. I also studied quasi-elastic Compton events to cross-check the luminosity measurement using the 2003- 2004 and 2005 data. Indeed, this process has a well calculable cross section and a clear experimental signature. The leptonic final state consists of a coplanar e-gamma system, both observable in the central H1 detector. (author)

  16. Luminosity function of white dwarfs

    International Nuclear Information System (INIS)

    Trigonometric parallaxes, optical colors, and spectrophotometry are used to derive an empirical luminosity function for cool white dwarfs using the 1/V(max) method. To facilitate comparison with theoretical cooling curves, relations for cool white dwarfs are estimated for T(eff) versus M(V) and for M(V) versus M(bol). The results show that a downturn occurs in the distribution of cool degenerate stars near log luminosity equals about -4.4. The indicated local space density of observed degenerate dwarfs is 0.003 stars/pc exp 3, which corresponds to about 1 percent of the dynamical mass density in the solar neighborhood. 107 references

  17. Luminosity monitors at the LHC

    CERN Document Server

    Khoze, V A; Orava, Risto; Ryskin, M G

    2001-01-01

    We study the theoretical accuracy of various methods that have been proposed to measure the luminosity of the LHC pp collider, as well as for Run II of the Tevatron p barp collider. In particular we consider methods based on (i) the total and forward elastic data, (ii) lepton-pair production and (iii) W and Z production.

  18. Precision luminosity measurements at LHCb

    CERN Document Server

    Aaij, Roel; Adinolfi, Marco; Affolder, Anthony; Ajaltouni, Ziad; Akar, Simon; Albrecht, Johannes; Alessio, Federico; Alexander, Michael; Ali, Suvayu; Alkhazov, Georgy; Alvarez Cartelle, Paula; Alves Jr, Antonio Augusto; Amato, Sandra; Amerio, Silvia; Amhis, Yasmine; An, Liupan; Anderlini, Lucio; Anderson, Jonathan; Andreassen, Rolf; Andreotti, Mirco; Andrews, Jason; Appleby, Robert; Aquines Gutierrez, Osvaldo; Archilli, Flavio; Artamonov, Alexander; Artuso, Marina; Aslanides, Elie; Auriemma, Giulio; Baalouch, Marouen; Bachmann, Sebastian; Back, John; Badalov, Alexey; Baesso, Clarissa; Baldini, Wander; Barlow, Roger; Barschel, Colin; Barsuk, Sergey; Barter, William; Batozskaya, Varvara; Battista, Vincenzo; Bay, Aurelio; Beaucourt, Leo; Beddow, John; Bedeschi, Franco; Bediaga, Ignacio; Belogurov, Sergey; Belous, Konstantin; Belyaev, Ivan; Ben-Haim, Eli; Bencivenni, Giovanni; Benson, Sean; Benton, Jack; Berezhnoy, Alexander; Bernet, Roland; Bettler, Marc-Olivier; van Beuzekom, Martinus; Bien, Alexander; Bifani, Simone; Bird, Thomas; Bizzeti, Andrea; Bjørnstad, Pål Marius; Blake, Thomas; Blanc, Frédéric; Blouw, Johan; Blusk, Steven; Bocci, Valerio; Bondar, Alexander; Bondar, Nikolay; Bonivento, Walter; Borghi, Silvia; Borgia, Alessandra; Borsato, Martino; Bowcock, Themistocles; Bowen, Espen Eie; Bozzi, Concezio; Brambach, Tobias; Bressieux, Joël; Brett, David; Britsch, Markward; Britton, Thomas; Brodzicka, Jolanta; Brook, Nicholas; Brown, Henry; Bursche, Albert; Buytaert, Jan; Cadeddu, Sandro; Calabrese, Roberto; Calvi, Marta; Calvo Gomez, Miriam; Campana, Pierluigi; Campora Perez, Daniel; Carbone, Angelo; Carboni, Giovanni; Cardinale, Roberta; Cardini, Alessandro; Carson, Laurence; Carvalho Akiba, Kazuyoshi; Casse, Gianluigi; Cassina, Lorenzo; Castillo Garcia, Lucia; Cattaneo, Marco; Cauet, Christophe; Cenci, Riccardo; Charles, Matthew; Charpentier, Philippe; Chefdeville, Maximilien; Chen, Shanzhen; Cheung, Shu-Faye; Chiapolini, Nicola; Chrzaszcz, Marcin; Ciba, Krzystof; Cid Vidal, Xabier; Ciezarek, Gregory; Clarke, Peter; Clemencic, Marco; Cliff, Harry; Closier, Joel; Coco, Victor; Cogan, Julien; Cogneras, Eric; Cojocariu, Lucian; Collazuol, Gianmaria; Collins, Paula; Comerma-Montells, Albert; Contu, Andrea; Cook, Andrew; Coombes, Matthew; Coquereau, Samuel; Corti, Gloria; Corvo, Marco; Counts, Ian; Couturier, Benjamin; Cowan, Greig; Craik, Daniel Charles; Cruz Torres, Melissa Maria; Cunliffe, Samuel; Currie, Robert; D'Ambrosio, Carmelo; Dalseno, Jeremy; David, Pascal; David, Pieter; Davis, Adam; De Bruyn, Kristof; De Capua, Stefano; De Cian, Michel; De Miranda, Jussara; De Paula, Leandro; De Silva, Weeraddana; De Simone, Patrizia; Dean, Cameron Thomas; Decamp, Daniel; Deckenhoff, Mirko; Del Buono, Luigi; Déléage, Nicolas; Derkach, Denis; Deschamps, Olivier; Dettori, Francesco; Di Canto, Angelo; Dijkstra, Hans; Donleavy, Stephanie; Dordei, Francesca; Dorigo, Mirco; Dosil Suárez, Alvaro; Dossett, David; Dovbnya, Anatoliy; Dreimanis, Karlis; Dujany, Giulio; Dupertuis, Frederic; Durante, Paolo; Dzhelyadin, Rustem; Dziurda, Agnieszka; Dzyuba, Alexey; Easo, Sajan; Egede, Ulrik; Egorychev, Victor; Eidelman, Semen; Eisenhardt, Stephan; Eitschberger, Ulrich; Ekelhof, Robert; Eklund, Lars; El Rifai, Ibrahim; Elsasser, Christian; Ely, Scott; Esen, Sevda; Evans, Hannah Mary; Evans, Timothy; Falabella, Antonio; Färber, Christian; Farinelli, Chiara; Farley, Nathanael; Farry, Stephen; Fay, Robert; Ferguson, Dianne; Fernandez Albor, Victor; Ferreira Rodrigues, Fernando; Ferro-Luzzi, Massimiliano; Filippov, Sergey; Fiore, Marco; Fiorini, Massimiliano; Firlej, Miroslaw; Fitzpatrick, Conor; Fiutowski, Tomasz; Fol, Philip; Fontana, Marianna; Fontanelli, Flavio; Forty, Roger; Francisco, Oscar; Frank, Markus; Frei, Christoph; Frosini, Maddalena; Fu, Jinlin; Furfaro, Emiliano; Gallas Torreira, Abraham; Galli, Domenico; Gallorini, Stefano; Gambetta, Silvia; Gandelman, Miriam; Gandini, Paolo; Gao, Yuanning; García Pardiñas, Julián; Garofoli, Justin; Garra Tico, Jordi; Garrido, Lluis; Gascon, David; Gaspar, Clara; Gauld, Rhorry; Gavardi, Laura; Geraci, Angelo; Gersabeck, Evelina; Gersabeck, Marco; Gershon, Timothy; Ghez, Philippe; Gianelle, Alessio; Gianì, Sebastiana; Gibson, Valerie; Giubega, Lavinia-Helena; Gligorov, Vladimir; Göbel, Carla; Golubkov, Dmitry; Golutvin, Andrey; Gomes, Alvaro; Gotti, Claudio; Grabalosa Gándara, Marc; Graciani Diaz, Ricardo; Granado Cardoso, Luis Alberto; Graugés, Eugeni; Graziani, Giacomo; Grecu, Alexandru; Greening, Edward; Gregson, Sam; Griffith, Peter; Grillo, Lucia; Grünberg, Oliver

    2014-01-01

    Measuring cross-sections at the LHC requires the luminosity to be determined accurately at each centre-of-mass energy $\\sqrt{s}$. In this paper results are reported from the luminosity calibrations carried out at the LHC interaction point 8 with the LHCb detector for $\\sqrt{s}$ = 2.76, 7 and 8 TeV (proton-proton collisions) and for $\\sqrt{s_{NN}}$ = 5 TeV (proton-lead collisions). Both the "van der Meer scan" and "beam-gas imaging" luminosity calibration methods were employed. It is observed that the beam density profile cannot always be described by a function that is factorizable in the two transverse coordinates. The introduction of a two-dimensional description of the beams improves significantly the consistency of the results. For proton-proton interactions at $\\sqrt{s}$ = 8 TeV a relative precision of the luminosity calibration of 1.47% is obtained using van der Meer scans and 1.43% using beam-gas imaging, resulting in a combined precision of 1.12%. Applying the calibration to the full data set determin...

  19. The High Luminosity LHC Project

    CERN Document Server

    Bruning, O

    2015-01-01

    This presentation reviews the status of the high luminosity LHC project, and highlights the main challenges from the technology and beam physics point of view. It will mention the outcome of the 2015 Cost and Schedule review for the HL-LHC project and summarizes the status of the high field quadrupole and crab cavity development.

  20. Upsilon spectroscopy at high luminosities

    International Nuclear Information System (INIS)

    This report discusses the advantages of high luminosity running on the bb-bar system as a test of QCD and the quark-antiquark forces. The author limits himself to the cases of 1,000 pb/sup -1//year and 10,000 pb/sup -1//year, and what physics goals can be achieved at these integrated luminosity levels. A summary of theoretical spectroscopic predictions is presented, together with a detailed evaluation of the decays 3/sup 3/S-> ππ1/sup 1/P/sub 1/->ππγ1/sup 1/S/sub o/ and 1/sup 3/S/sub 1/->γ1/sup 1/S/sub o/. A brief discussion of other possible 'exotic' spectrosocpy is given

  1. Detectors and luminosity for hadron colliders

    International Nuclear Information System (INIS)

    Three types of very high energy hadron-hadron colliders are discussed in terms of the trade-off between energy and luminosity. The useable luminosity depends both on the physics under study and the rate capabilities of the detector

  2. Optimizing integrated luminosity of future hadron colliders

    CERN Document Server

    AUTHOR|(CDS)2108454; Schulte, Daniel; Zimmermann, Frank

    2015-01-01

    The integrated luminosity, a key figure of merit for any particle-physics collider, is closely linked to the peak luminosity and to the beam lifetime. The instantaneous peak luminosity of a collider is constrained by a number of boundary conditions, such as the available beam current, the maximum beam-beam tune shift with acceptable beam stability and reasonable luminosity lifetime (i.e., the empirical “beam-beam limit”), or the event pileup in the physics detectors. The beam lifetime at high-luminosity hadron colliders is largely determined by particle burn off in the collisions. In future highest-energy circular colliders synchrotron radiation provides a natural damping mechanism, which can be exploited for maximizing the integrated luminosity. In this article, we derive analytical expressions describing the optimized integrated luminosity, the corresponding optimum store length, and the time evolution of relevant beam parameters, without or with radiation damping, while respecting a fixed maximum value...

  3. First high-luminosity insertion in the ISR

    International Nuclear Information System (INIS)

    One of the means proposed to increase the luminosity in storage rings, a so-called low-? insertion, was successfully put into operation in the Intersecting Storage Rings (ISR). The installation of five quadrupoles in each ring around one intersection resulted in a reduction of beam height by a factor 2.3. Due to proper matching, the perturbation to the rest of the machine was negligible. With circulating beams of 20 A and 24 A, a luminosity of 2.11 x 1031 cm-2 s-1 was achieved. The results of tests are given, and are compared to theoretical forecasts. A short description of the hardware used is presented. (auth)

  4. Perspectives on Higher Luminosity B-Factories

    International Nuclear Information System (INIS)

    The present B-factories PEP-II and KEKB have reached luminosities of 4-6 x 1033/cm2/s and delivered integrated luminosity at rates in excess of 6 fb-1 per month [1,2]. The recent turn on of these two B-Factories has shown that modern accelerator physics, design, and engineering can produce colliders that rapidly reach their design luminosities and deliver integrated luminosities capable of frontier particle physics discoveries. PEP-II and KEK-B with ongoing upgrade programs should reach luminosities of over 1034/cm2/s in a few years and with more aggressive improvements may reach luminosities of order 4 x 1034/cm2/s by the end of the decade. However, due to particle physics requirements, the next generation B-Factory may require significantly more luminosity. Initial parameters of a very high luminosity e+e- B-Factory or Super B-Factory (SBF) are being developed incorporating several new ideas from the successful operation of the present generation e+e- accelerators [3,4]. A luminosity approaching 1036 cm-2s-1 may be possible. Furthermore, the ratio of average to peak luminosity may be increased by 30% due to continuous injection. The operation of this new accelerator will be qualitatively different from present e+e- colliders due to this continuous injection

  5. The intrinsic quasar luminosity function: Accounting for accretion disk anisotropy

    International Nuclear Information System (INIS)

    Quasar luminosity functions are a fundamental probe of the growth and evolution of supermassive black holes. Measuring the intrinsic luminosity function is difficult in practice, due to a multitude of observational and systematic effects. As sample sizes increase and measurement errors drop, characterizing the systematic effects is becoming more important. It is well known that the continuum emission from the accretion disk of quasars is anisotropic—in part due to its disk-like structure—but current luminosity function calculations effectively assume isotropy over the range of unobscured lines of sight. Here, we provide the first steps in characterizing the effect of random quasar orientations and simple models of anisotropy on observed luminosity functions. We find that the effect of orientation is not insignificant and exceeds other potential corrections such as those from gravitational lensing of foreground structures. We argue that current observational constraints may overestimate the intrinsic luminosity function by as much as a factor of ∼2 on the bright end. This has implications for models of quasars and their role in the universe, such as quasars' contribution to cosmological backgrounds.

  6. The Ultraviolet Luminosity Function of the Earliest Galaxies

    CERN Document Server

    O'Shea, Brian W; Xu, Hao; Norman, Michael L

    2015-01-01

    In this paper, we present the first results from the Renaissance Simulations, a suite of extremely high-resolution and physics-rich AMR calculations of high redshift galaxy formation performed on the Blue Waters supercomputer. These simulations contain hundreds of well-resolved galaxies at $z \\sim 25-8$, and make several novel, testable predictions. Most critically, we show that the ultraviolet luminosity function of our simulated galaxies is consistent with observations of high-z galaxy populations at the bright end of the luminosity function (M$_{1600} \\leq -17$), but at lower luminosities is essentially flat rather than rising steeply, as has been inferred by Schechter function fits to high-z observations. This flattening of the luminosity function is due to two factors: (i) the strong dependence of the stellar fraction on halo virial mass in our simulated galaxy population, with lower-mass halos having systematically lower stellar fractions and thus lower luminosities at a given halo virial mass; and (ii)...

  7. Determination of the Absolute Luminosity at the LHC

    CERN Document Server

    White, Simon Mathieu; Puzo, P

    2010-01-01

    For particle colliders, the most important performance parameters are the beam energy and the luminosity. High energies allow the particle physics experiments to study and observe new effects. The luminosity describes the ability of the collider to produce the required number of useful interactions or events. It is defined as the proportionality factor between the event rate, measured by the experiments, and the cross section of the observed event which describes its probability to occur. The absolute knowledge of the luminosity therefore allows for the experiments to measure the absolute cross sections. The Large Hadron Collider (LHC) was designed to produce proton proton collisions at a center of mass energy of 14 TeV. This energy would be the highest ever reached in a particle accelerator. The knowledge and understanding of particle physics at such high energy is based on simulations and theoretical predictions. As opposed to e+ e- colliders, for which the Bhabba scattering cross section can be accurately ...

  8. Differential Luminosity Measurement using Bhabha Events

    CERN Document Server

    Poss, Stephane

    2013-01-01

    A good knowledge of the luminosity spectrum is mandatory for many measurements at future e+e- colliders. As the beam-parameters determining the luminosity spectrum cannot be measured precisely, the luminosity spectrum has to be measured through a gauge process with the detector. The measured distributions, used to reconstruct the spectrum, depend on Initial State Radiation, cross-section, and Final State Radiation. To extract the basic luminosity spectrum, a parametric model of the luminosity spectrum is created, in this case the spectrum at the 3 TeV CLIC. The model is used in a reweighting technique to extract the luminosity spectrum from measured Bhabha event observables, taking all relevant effects into account. The centre-of-mass energy spectrum is reconstructed within 5% over the full validity range of the model. The reconstructed spectrum does not result in a significant bias or systematic uncertainty in the exemplary physics benchmark process of smuon pair production.

  9. Luminosity Spectrum Reconstruction at Linear Colliders

    CERN Document Server

    Poss, Stéphane

    2014-01-01

    A good knowledge of the luminosity spectrum is mandatory for many measurements at future e+e- colliders. As the beam-parameters determining the luminosity spectrum cannot be measured precisely, the luminosity spectrum has to be measured through a gauge process with the detector. The measured distributions, used to reconstruct the spectrum, depend on Initial State Radiation, cross-section, and Final State Radiation. To extract the basic luminosity spectrum, a parametric model of the luminosity spectrum is created, in this case the spectrum at the 3 TeV Compact Linear Collider (CLIC). The model is used within a reweighting technique to extract the luminosity spectrum from measured Bhabha event observables, taking all relevant effects into account. The centre-of-mass energy spectrum is reconstructed within 5% over the full validity range of the model. The reconstructed spectrum does not result in a significant bias or systematic uncertainty in the exemplary physics benchmark process of smuon pair production.

  10. Luminosity Measurements with the ATLAS Detector

    CERN Document Server

    Maettig, Stefan; Pauly, T

    For almost all measurements performed at the Large Hadron Collider (LHC) one crucial ingredient is the precise knowledge about the integrated luminosity. The determination and precision on the integrated luminosity has direct implications on any cross-section measurement, and its instantaneous measurement gives important feedback on the conditions at the experimental insertions and on the accelerator performance. ATLAS is one of the main experiments at the LHC. In order to provide an accurate and reliable luminosity determination, ATLAS uses a variety of different sub-detectors and algorithms that measure the luminosity simultaneously. One of these sub-detectors are the Beam Condition Monitors (BCM) that were designed to protect the ATLAS detector from potentially dangerous beam losses. Due to its fast readout and very clean signals this diamond detector is providing in addition since May 2011 the official ATLAS luminosity. This thesis describes the calibration and performance of the BCM as a luminosity detec...

  11. Optimizing integrated luminosity of future hadron colliders

    Science.gov (United States)

    Benedikt, Michael; Schulte, Daniel; Zimmermann, Frank

    2015-10-01

    The integrated luminosity, a key figure of merit for any particle-physics collider, is closely linked to the peak luminosity and to the beam lifetime. The instantaneous peak luminosity of a collider is constrained by a number of boundary conditions, such as the available beam current, the maximum beam-beam tune shift with acceptable beam stability and reasonable luminosity lifetime (i.e., the empirical "beam-beam limit"), or the event pileup in the physics detectors. The beam lifetime at high-luminosity hadron colliders is largely determined by particle burn off in the collisions. In future highest-energy circular colliders synchrotron radiation provides a natural damping mechanism, which can be exploited for maximizing the integrated luminosity. In this article, we derive analytical expressions describing the optimized integrated luminosity, the corresponding optimum store length, and the time evolution of relevant beam parameters, without or with radiation damping, while respecting a fixed maximum value for the total beam-beam tune shift or for the event pileup in the detector. Our results are illustrated by examples for the proton-proton luminosity of the existing Large Hadron Collider (LHC) at its design parameters, of the High-Luminosity Large Hadron Collider (HL-LHC), and of the Future Circular Collider (FCC-hh).

  12. Redshift and luminosity dependence of the linear sizes of powerful radio galaxies

    International Nuclear Information System (INIS)

    The redshift and luminosity dependence of the linear sizes of powerful radio galaxies on epoch is investigated using samples of similar radio luminosity extending to z larger than about one. It is found that a strong evolution in linear sizes with epoch of a given form is required for q0 = 1/2. Fairly strong evolution is required even if the steep-spectrum compact sources which make an increasing contribution with redshift are excluded from the analysis. When linear size distributions of samples of radio galaxies of different luminosities are compared at similar redshifts, it is found that, at constant redshift, linear sizes increase with luminosity in a given way. Strong evidence is found that, for radio galaxies, the epoch and luminosity dependence of linear sizes can be factorized over the entire range of luminosity and redshift space. 41 references

  13. Ether, Luminosity and Galactic Source Counts

    Science.gov (United States)

    Tomaschitz, Roman

    1998-08-01

    An interpretation of the cosmological redshift in terms of a cosmic ether is given. We study a Robertson-Walker cosmology in which the ether is phenomenologically defined by a homogeneous and isotropic permeability tensor. The speed of light becomes so a function of cosmic time like in a dielectric medium. However, the cosmic ether is dispersion free, it does not lead to a broadening of spectral lines. Locally, in Euclidean frames, the scale factors of the permeability tensor get absorbed in the fundamental constants. Mass and charge scale with cosmic time, and so do atomic energy levels. This substantially changes the interpretation of the cosmological redshift as a Doppler shift. Photon frequencies are independent of the expansion factor; their time scaling is determined by the permeability tensor. The impact of the ether on the luminosity-distance, on the distance-redshift relation, and on galactic number counts is discussed. The Hubble constant is related to the scale factors of the metric and the permeability tensor. We study the effects of the ether at first in comoving Robertson-Walker coordinates, and then, in the context of a flat but expanding space- time, in the globally geodesic rest frames of galactic observers.

  14. Ether, Luminosity and Galactic Source Counts

    CERN Document Server

    Tomaschitz, R

    1998-01-01

    An interpretation of the cosmological redshift in terms of a cosmic ether is given. We study a Robertson-Walker cosmology in which the ether is phenomenologically defined by a homogeneous and isotropic permeability tensor. The speed of light becomes so a function of cosmic time like in a dielectric medium. However, the cosmic ether is dispersion free, it does not lead to a broadening of spectral lines. Locally, in Euclidean frames, the scale factors of the permeability tensor get absorbed in the fundamental constants. Mass and charge scale with cosmic time, and so do atomic energy levels. This substantially changes the interpretation of the cosmological redshift as a Doppler shift. Photon frequencies are independent of the expansion factor; their time scaling is determined by the permeability tensor. The impact of the ether on the luminosity-distance, on the distance-redshift relation, and on galactic number counts is discussed. The Hubble constant is related to the scale factors of the metric and the permeab...

  15. Distance errors and the stellar luminosity function

    International Nuclear Information System (INIS)

    A study of the stellar luminosity function in the region of the north galactic pole is described. The method is based on photometric parallaxes derived from the V-1 colour index. A complete sample of stars is defined with I≤16, V> 13, V-I> 1.5 and within 130 pc of the Sun. JHK photometry is obtained for stars with V-I>2.9 to check the V-I calibration and exclude contamination by giants. It is demonstrated that application of the classical Malmquist bias derives an incorrect luminosity function. A detailed discussion is given of the effects of Malmquist-type biases on luminosity functions and a method presented which effectively deconvolves the observed luminosity function to determine the intrinsic luminosity function. The method is applied to the data in the north galactic pole sample. (author)

  16. Luminosity monitoring in ATLAS with MPX detectors

    International Nuclear Information System (INIS)

    The ATLAS-MPX detectors are based on the Medipix2 silicon devices designed by CERN for the detection of multiple types of radiation. Sixteen such detectors were successfully operated in the ATLAS detector at the LHC and collected data independently of the ATLAS data-recording chain from 2008 to 2013. Each ATLAS-MPX detector provides separate measurements of the bunch-integrated LHC luminosity. An internal consistency for luminosity monitoring of about 2% was demonstrated. In addition, the MPX devices close to the beam are sensitive enough to provide relative-luminosity measurements during van der Meer calibration scans, in a low-luminosity regime that lies below the sensitivity of the ATLAS calorimeter-based bunch-integrating luminometers. Preliminary results from these luminosity studies are presented for 2012 data taken at √s = 8 TeV proton-proton collisions

  17. Luminosity determination at HERA-B

    International Nuclear Information System (INIS)

    A detailed description of an original method used to measure the luminosity accumulated by the HERA-B experiment for a data sample taken during the 2002-2003 HERA running period is reported. We show that, with this method, a total luminosity measurement can be achieved with a typical precision, including overall systematic uncertainties, at a level of 5% or better. We also report evidence for the detection of δ-rays generated in the target and comment on the possible use of such delta rays to measure luminosity. (orig.)

  18. Luminosity determination at HERA-B

    International Nuclear Information System (INIS)

    A detailed description of an original method used to measure the luminosity accumulated by the HERA-B experiment for a data sample taken during the 2002-2003 HERA running period is reported. We show that, with this method, a total luminosity measurement can be achieved with a typical precision, including overall systematic uncertainties, at a level of 5% or better. We also report evidence for the detection of δ-rays generated in the target and comment on the possible use of such delta rays to measure luminosity

  19. Luminosity determination at HERA-B

    CERN Document Server

    Abt, I; Agari, M; Albrecht, H; Aleksandrov, A; Amaral, V S; Amorim, A; Aplin, S J; Aushev, V; Bagaturia, Yu S; Balagura, V; Bargiotti, M; Barsukova, O; Bastos, J; Batista, J; Bauer, C; Bauer, T S; Belkov, A; Belkov, Ar; Belotelov, I; Bertin, A; Bobchenko, B; Böcker, M; Bogatyrev, A; Böhm, G; Brauer, M; Bruinsma, M; Bruschi, M; Buchholz, P; Buran, T; Carvalho, J; Conde, P; Cruse, C; Dam, M; Danielsen, K M; Danilov, M; De Castro, S; Deppe, H; Dong, X; Dreis, H B; Egorytchev, V; Ehret, K; Eisele, F; Emeliyanov, D; Essenov, S; Fabbri, L; Faccioli, P; Feuerstack-Raible, M; Flammer, J; Fominykh, B; Funcke, M; Garrido, L; Gellrich, A; Giacobbe, B; Glass, J; Goloubkov, D; Golubkov, Y; Golutvin, A; Golutvin, I A; Gorbounov, I; Gorisek, A; Gouchtchine, O; Goulart, D C; Gradl, S; Gradl, W; Grimaldi, F; Groth-Jensen, J; Guilitsky, Yu; Hansen, J D; Hernández, J M; Hofmann, W; Hohlmann, M; Hott, T; Hulsbergen, W; Husemann, U; Igonkina, O; Ispiryan, M; Jagla, T; Jiang, C; Kapitza, H; Karabekyan, S; Karpenko, N; Keller, S; Kessler, J; Khasanov, F; Kiryushin, Yu T; Kisel, I; Klinkby, E; Knöpfle, K T; Kolanoski, H; Korpar, S; Krauss, C; Kreuzer, P; Krizan, P; Krücker, D; Kupper, S; Kvaratskheliia, T; Lanyov, A; Lau, K; Lewendel, B; Lohse, T; Lomonosov, B; Männer, R; Mankel, R; Masciocchi, S; Massa, I; Matchikhilian, I; Medin, G; Medinnis, M; Mevius, M; Michetti, A; Mikhailov, Yu; Mizuk, R; Muresan, R; Zur Nedden, M; Negodaev, M; Nörenberg, M; Nowak, S; Núñez-Pardo de Vera, M T; Ouchrif, M; Ould-Saada, F; Padilla, C; Peralta, D; Pernack, R; Pestotnik, R; Petersen, B AA; Piccinini, M; Pleier, M A; Poli, M; Popov, V; Pose, D; Prystupa, S; Pugatch, V; Pylypchenko, Y; Pyrlik, J; Reeves, K; Ressing, D; Rick, H; Riu, I; Robmann, P; Rostovtseva, I; Rybnikov, V; Sánchez, F; Sbrizzi, A; Schmelling, M; Schmidt, B; Schreiner, A; Schröder, H; Schwanke, U; Schwartz, A J; Schwarz, A S; Schwenninger, B; Schwingenheuer, B; Sciacca, F; Semprini-Cesari, N; Shuvalov, S; Silva, L; Sozuer, L; Solunin, S; Somov, A; Somov, S; Spengler, J; Spighi, R; Spiridonov, A; Stanovnik, A; Staric, M; Stegmann, C; Subramanian, H S; Symalla, M; Tikhomirov, I; Titov, M; Tsakov, I; Uwer, U; Van Eldik, C; Vasilev, Yu; Villa, M; Vitale, A; Vukotic, I; Wahlberg, H; Walenta, A H; Walter, M; Wang, J J; Wegener, D; Werthenbach, U; Wolters, H; Wurth, R; Wurz, A; Xella, S M; Zaitsev, Yu; Zavertyaev, M; Zeuner, T; Zhelezov, A; Zheng, Z; Zimmermann, R; Zivko, T; Zoccoli, A

    2007-01-01

    A detailed description of an original method used to measure the luminosity accumulated by the HERA-B experiment for a data sample taken during the 2002-2003 HERA running period is reported. We show that, with this method, a total luminosity measurement can be achieved with a typical precision, including overall systematic uncertainties, at a level of 5% or better. We also report evidence for the detection of delta-rays generated in the target and comment on the possible use of such delta rays to measure luminosity.

  20. Prospects for the high-luminosity LHC

    International Nuclear Information System (INIS)

    This note reviews the main physics topics accessible with the high-luminosity LHC program (HL-LHC). It should deliver p-p collisions at √(s)=14TeV with an integrated luminosity of 3000fb−1. Results are presented in perspective with the previous period with ten times less luminosity. The ATLAS and CMS collaborations released expected results for this program assuming similar detector performance as today within more difficult conditions. The Higgs boson branching ratios and couplings to fermions/bosons will be measured at few percent level. The main discovery limits for the search of new particles or phenomena beyond the Standard Model are presented

  1. Luminosity determination at HERA-B

    Energy Technology Data Exchange (ETDEWEB)

    Abt, I. [Max-Planck-Institut fuer Physik, Muenchen (Germany); Adams, M. [Dortmund Univ. (Germany). Inst. fuer Physik; Agari, M. [Max-Planck-Institut fuer Kernphysik, Heidelberg (DE)] (and others)

    2007-05-15

    A detailed description of an original method used to measure the luminosity accumulated by the HERA-B experiment for a data sample taken during the 2002-2003 HERA running period is reported. We show that, with this method, a total luminosity measurement can be achieved with a typical precision, including overall systematic uncertainties, at a level of 5% or better. We also report evidence for the detection of {delta}-rays generated in the target and comment on the possible use of such delta rays to measure luminosity. (orig.)

  2. ISR Superconducting High-Luminosity (low beta ) insertion

    CERN Multimedia

    1981-01-01

    The photograph shows two of the 8 Superconducting Quadrupoles installed in ISR intersection I8 with their helium supply flexible lines,vacuum equipment,power and signal cables. The increase of luminosity produced by this insertion was above a factor 7. On the right one can see part of Open-Axial-Field Magnet. The person on the left side is Stephan Pichler. See also photo 7702690 and its abstract.

  3. Where are the z=4 Lyman Break Galaxies? Results from Conditional Luminosity Function Models of Luminosity-dependent Correlation Functions

    CERN Document Server

    Cooray, A R; Cooray, Asantha; Ouchi, Masami

    2006-01-01

    Using the conditional luminosity function (CLF) -- the luminosity distribution of galaxies in a dark matter halo -- as a way to model galaxy statistics, we study how z=4 Lyman Break Galaxies (LBGs) are distributed in dark matter halos. For this purpose, we measure luminosity-dependent clustering of LBGs in the Subaru/XMM-Newton Deep Field by separating a sample of 16,920 galaxies to three magnitude bins in i'-band between 24.5 and 27.5. Our models fits to data show a possible trend for more luminous galaxies to appear as satellites in more massive halos. The satellite fraction of galaxies at z=4 in these magnitude bins is 0.13 to 0.3, 0.09 to 0.22, and 0.03 to 0.14, respectively, where the 1 sigma ranges account for differences coming from two different estimates of the z=4 LF from the literature. To jointly explain the LF and the large-scale linear bias factor of z=4 LBGs as a function of rest-UV luminosity requires central galaxies to be brighter in UV at z =4 than present-day galaxies in same dark matter m...

  4. Systematic Biases in Galaxy Luminosity Functions

    CERN Document Server

    Dalcanton, J J

    1997-01-01

    Both the detection of galaxies and the derivation of the luminosity function depend upon isophotal magnitudes, implicitly in the first case, and explicitly in the latter. However, unlike perfect point sources, the fraction of a galaxy's light contained within the limiting isophote is a function of redshift, due to the combined effects of the point spread function and cosmological dimming. This redshift variation in the measured isophotal luminosity can strongly affect the derived luminosity function. Using simulations which include the effects of seeing upon both disk and elliptical galaxies, we explore the size of the systematic biases which can result from ignoring the redshift variation in the fraction of detected light. We show that the biases lead to underestimates in the normalization of the luminosity function, as well as changes in shape. The size of the bias depends upon redshift, and thus can mimic galaxy evolution. Surprisingly, these biases can be extremely large without affecting . However, these...

  5. Luminosity and spectral evolution of QSOs

    CERN Document Server

    Choi, Y Y; Yi, I S

    1999-01-01

    We apply the observed spectral states of the Galactic black hole candidates (GBHCs) to the quasi-stellar object (QSO) luminosity evolution based on the correlation between luminosity and the spectrum, which is strongly supported by the similarities of emission mechanisms in GBHCs and QSOs. We derive the QSO luminosity evolution trends in the UV/optical and the X-ray energy bands and demonstrate that their trends are significantly affected by the spectral evolution. Each energy band shows distinct evolution properties. We test one of the widely discussed cosmological evolution scenarios of QSOs, in which QSOs evolve as a single long-lived population, and show that the resulting luminosity functions seen in different energy bands exhibit distinguishable and potentially observable evolution signatures in the X-ray energy bands.

  6. A survey of Low Luminosity Compact sources

    CERN Document Server

    Kunert-Bajraszewska, Magdalena

    2009-01-01

    Based on the FIRST and SDSS catalogues a flux density limited sample of weak Compact Steep Spectrum (CSS) sources with radio luminosity below 10^26 [W/Hz] at 1.4 GHz has been constructed. Our previous multifrequency observations of CSS sources have shown that low luminosity small-scale objects can be strong candidates for compact faders. This finding supports the idea that some small-size radio sources are short-lived phenomena because of a lack of significant fuelling. They never 'grow up' to become FRI or FRII objects. This new sample marks the start of a systematical study of the radio properties and morphologies of the population of low luminosity compact (LLC) objects. An investigation of this new sample should also lead to a better understanding of compact faders. In this paper, the results of the first stage of the new project - the L-band MERLIN observations of 44 low luminosity CSS sources are presented.

  7. THE z = 5 QUASAR LUMINOSITY FUNCTION FROM SDSS STRIPE 82

    Energy Technology Data Exchange (ETDEWEB)

    McGreer, Ian D.; Fan Xiaohui [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065 (United States); Jiang Linhua [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Richards, Gordon T. [Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Strauss, Michael A. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Ross, Nicholas P.; White, Martin [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 92420 (United States); Shen Yue [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Schneider, Donald P.; Brandt, W. Niel [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Myers, Adam D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); DeGraf, Colin [McWilliams Center for Cosmology, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Glikman, Eilat [Department of Physics and Yale Center for Astronomy and Astrophysics, Yale University, P.O. Box 208121, New Haven, CT 06520-8121 (United States); Ge Jian [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611 (United States); Streblyanska, Alina, E-mail: imcgreer@as.arizona.edu [Instituto de Astrofisica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain)

    2013-05-10

    We present a measurement of the Type I quasar luminosity function at z = 5 using a large sample of spectroscopically confirmed quasars selected from optical imaging data. We measure the bright end (M{sub 1450} < -26) with Sloan Digital Sky Survey (SDSS) data covering {approx}6000 deg{sup 2}, then extend to lower luminosities (M{sub 1450} < -24) with newly discovered, faint z {approx} 5 quasars selected from 235 deg{sup 2} of deep, coadded imaging in the SDSS Stripe 82 region (the celestial equator in the Southern Galactic Cap). The faint sample includes 14 quasars with spectra obtained as ancillary science targets in the SDSS-III Baryon Oscillation Spectroscopic Survey, and 59 quasars observed at the MMT and Magellan telescopes. We construct a well-defined sample of 4.7 < z < 5.1 quasars that is highly complete, with 73 spectroscopic identifications out of 92 candidates. Our color selection method is also highly efficient: of the 73 spectra obtained, 71 are high-redshift quasars. These observations reach below the break in the luminosity function (M{sub 1450}{sup *}{approx}-27). The bright-end slope is steep ({beta} {approx}< -4), with a constraint of {beta} < -3.1 at 95% confidence. The break luminosity appears to evolve strongly at high redshift, providing an explanation for the flattening of the bright-end slope reported previously. We find a factor of {approx}2 greater decrease in the number density of luminous quasars (M{sub 1450} < -26) from z = 5 to z = 6 than from z = 4 to z = 5, suggesting a more rapid decline in quasar activity at high redshift than found in previous surveys. Our model for the quasar luminosity function predicts that quasars generate {approx}30% of the ionizing photons required to keep hydrogen in the universe ionized at z = 5.

  8. The luminosity function of field galaxies

    OpenAIRE

    Mahtessian, A. P.

    2011-01-01

    Schmidt's method for construction of luminosity function of galaxies is generalized by taking into account the dependence of density of galaxies from the distance in the near Universe. The logarithmical luminosity function (LLF) of field galaxies depending on morphological type is constructed. We show that the LLF for all galaxies, and also separately for elliptical and lenticular galaxies can be presented by Schechter function in narrow area of absolute magnitudes. The LLF of spiral galaxies...

  9. Operational results from the LHC luminosity monitors

    International Nuclear Information System (INIS)

    The luminosity monitors for the high luminosity regions in the LHC have been operating to monitor and optimize the luminosity since 2009. The device is a gas ionization chamber inside the neutral particle absorber 140 m from the interaction point and monitors showers produced by high energy neutral particles from the collisions. It has the ability to resolve the bunch-by-bunch luminosity as well as to survive the extreme level of radiation in the nominal LHC operation. We present operational results of the device during proton and lead ion operations in 2010 and make comparisons with measurements of experiments. The Large Hadron Collider (LHC) at CERN can accelerate proton and lead ion beams to 7 TeV and 547 TeV and produce collisions of these particles. Luminosity measures performance of the LHC and is particularly important for experiments in high luminosity interaction points (IPs), ATLAS (IP1) and CMS (IP5). To monitor and optimize the luminosities of these IPs, BRAN (Beam RAte Neutral) detectors (1, 2) have been installed and operating since the beginning of the 2009 operation (3). A neutral particle absorber (TAN) protects the D2 separation dipole from high energy forward neutral particles produced in the collisions (4). These neutral particles produce electromagnetic and hadronic showers inside the TAN and their energy flux is proportional to the collision rate and hence to the luminosity. The BRAN detector is an Argon gas ionization chamber installed inside the TANs on both sides of the IP1 and IP5 and monitors the relative changes in the luminosity by detecting the ionization due to these showers. When the number of collisions per bunch crossing (multiplicity) is small, the shower rate inside the TAN is also proportional to the luminosity. Hence, the detector is designed to operate by measuring either the shower rate (counting mode for low and intermediate luminosities) or the average shower flux (pulse height mode for high luminosities). The detector is also designed (1) to survive the extreme level of radiation (∼1 GGy in the nominal condition), (2) to resolve the shower from each bunch crossing (40 MHz in the nominal condition) and measure the bunch-by-bunch luminosities, and (3) to have four independent square shaped channels, each occupying a quadrant, making the detector sensitive to the crossing angle (1, 2). During the proton operation in 2010, the beam energy was 3.5 TeV and the multiplicity did not exceed four. Because the counting mode is still effective in such a condition (5), the BRAN were operated in the counting mode in 2010. This paper presents operational results of the BRANs during the operation in 2010 (mainly the proton operation) and makes comparisons with measurements of the experiments. The luminosity optimization is discussed in detail in (6) and so this paper focuses on measurements during the normal operation.

  10. Symmetric Moeller/Bhabha luminosity monitor for the OLYMPUS experiment

    International Nuclear Information System (INIS)

    The OLYMPUS experiment ran on the DORIS storage ring at DESY, Hamburg to measure the elastic cross sections for both positron and electron scattering from hydrogen to quantify the two-photon contribution to elastic ep scattering. Two-photon exchange is widely considered to be responsible for the the discrepancy in the proton form factor ratio determined using the Rosenbluth technique and polarization transfer. The experiment alternated daily between positron and electron beams at 2.01 GeV incident on an unpolarized, internal, hydrogen gas target. The luminosity delivered to the experiment was monitored by a redundant set of detectors: a high precision, symmetric Moeller/Bhabha calorimeter and a tracking telescope at 12 degrees. The symmetric Moeller/Bhabha calorimeter was built at Mainz and consisted of two symmetric arrays of lead fluoride crystals. Results on the performance of the SYMB luminosity monitor will be presented together with an overview of the OLYMPUS experiment.

  11. CLIC Post-Collision Line Luminosity Monitoring

    CERN Document Server

    Appleby, R B; Deacon, L; Geschwendtner, E

    2011-01-01

    The CLIC post collision line is designed to transport the un-collided beams and the products of the collided beams with a total power of 14MW to the main beam dump. Full Monte Carlo simulation has been done for the description of the CLIC luminosity monitoring in the post collision line. One method of the luminosity diagnostic is based on the detection of high energy muons produced by beamstrahlung photons in the main beam dump. The disrupted beam and the beamstrahlung photons produce at the order of 106 muons per bunch crossing per cm2, with energies higher than 10 GeV. Threshold Cherenkov counters are considered after the beam dump for the detection of these high energy muons. Another method for luminosity monitoring is presented using the direct detection of the beamstrahlung photons.

  12. Development of automatic luminosity calculation framework

    CERN Document Server

    Lavicka, Roman

    2015-01-01

    Up-to-date knowledge on the collected number of events and integrated luminosity is crucial for the ALICE data taking and trigger strategy planning. The purpose of the project is to develop a framework for the automatic recalculation of achieved statistics and integrated luminosity on a daily basis using information from the ALICE data base. We have been encouraged encouraged to work on the improvement of available luminosity calculation algorithms, in particular accounting for pile-up corrections. Results are represented in a form of trending plots and summary tables for different trigger classes and stored in the personal web site of the author with an outlook on the possibility to story it in the ALICE monitoring repository.

  13. Radio luminosity function of brightest cluster galaxies

    CERN Document Server

    Yuan, Z S; Wen, Z L

    2016-01-01

    By cross-matching the currently largest optical catalog of galaxy clusters and the NVSS radio survey database, we obtain the largest complete sample of brightest cluster galaxies (BCGs) in the redshift range of 0.05luminosity functions of BCGs from the largest complete sample of BCGs, and find that the functions depend on the optical luminosity of BCGs and the dynamical state of galaxy clusters. However, the radio luminosity function does not show significant evolution with redshift.

  14. Powering the High-Luminosity Triplets

    CERN Document Server

    Ballarino, A

    2015-01-01

    The powering of the magnets in the LHC High-Luminosity Triplets requires production and transfer of more than 150 kA of DC current. High precision power converters will be adopted, and novel High Temperature Superconducting (HTS) current leads and MgB2 based transfer lines will provide the electrical link between the power converters and the magnets. This chapter gives an overview of the systems conceived in the framework of the LHC High-Luminosity upgrade for feeding the superconducting magnet circuits. The focus is on requirements, challenges and novel developments.

  15. Luminosity Determination at HERA-B.

    OpenAIRE

    Abt, I.; Adams, M.; Agari, M.; ALBRECHT, H.; Aleksandrov, A.; Amaral, V.; Amorim, A; Aplin, S. J.; Aushev, V.; Bagaturia, Y.; Balagura, V.(Institute of Theoretical and Experimental Physics (ITEP), Moscow, Russia); Bargiotti, M.; Barsukova, O.; Bastos, J.; Batista, J.

    2007-01-01

    A detailed description of an original method used to measure the luminosity accumulated by the HERA-B experiment for a data sample taken during the 2002-2003 HERA running period is reported. We show that, with this method, a total luminosity measurement can be achieved with a typical precision, including overall systematic uncertainties, at a level of 5% or better. We also report evidence for the detection of delta-rays generated in the target and comment on the possible use of such delta ray...

  16. A universal GRB photon energy-peak luminosity relation

    CERN Document Server

    Willingale, R; Goad, M R; Osborne, J P; Page, K L; Tanvir, N R

    2007-01-01

    The energetics and emission mechanism of GRBs are not well understood. Here we demonstrate that the instantaneous peak flux or equivalent isotropic peak luminosity, L_iso ergs s^-1, rather than the integrated fluence or equivalent isotropic energy, E_iso ergs, underpins the known high-energy correlations. Using new spectral/temporal parameters calculated for 101 bursts with redshifts from BATSE, BeppoSAX, HETE-II and Swift we describe a parameter space which characterises the apparently diverse properties of the prompt emission. We show that a source frame characteristic-photon-energy/peak luminosity ratio, K_z, can be constructed which is constant within a factor of 2 for all bursts whatever their duration, spectrum, luminosity and the instrumentation used to detect them. The new parameterization embodies the Amati relation but indicates that some correlation between E_peak and E_iso follows as a direct mathematical inference from the Band function and that a simple transformation of E_iso to L_iso yields a ...

  17. High-Luminosity LHC moves to the next phase

    CERN Multimedia

    2015-01-01

    This week saw several meetings vital for the medium-term future of CERN.    From Monday to Wednesday, the Resource Review Board, RRB, that oversees resource allocation in the LHC experiments, had a series of meetings. Thursday then saw the close-out meeting for the Hi-Lumi LHC design study, which was partially funded by the European Commission. These meetings focused on the High Luminosity upgrade for the LHC, which responds to the top priority of the European Strategy for Particle Physics adopted by the CERN Council in 2013. This upgrade will transform the LHC into a facility for precision studies, the logical next step for the high-energy frontier of particle physics. It is a challenging upgrade, both for the LHC and the detectors. The LHC is already the highest luminosity hadron collider ever constructed, generating up to a billion collisions per second at the heart of the detectors. The High Luminosity upgrade will see that number rise by a factor of five from 2025. For the detectors...

  18. Luminosity-Distances of IUE observed Active Galaxies

    Science.gov (United States)

    Doddamani, Vijayakumar H.; Vedavathi, P.

    2014-07-01

    Active galaxies are the most luminous objects observed in the Universe and are believed to be powered by mass accretion processes taking place in the vicinity of the central Super massive black hole (M BH >= 108M sun ). However, the details of the power generation mechanisms are not understood well yet. In this paper, we are presenting a comparative study of luminosity-distance estimations for the complete sample of active galaxies observed by IUE satellite by different methods. IUE has made UV spectroscopic observations of nearly 400 active galaxies comprising mostly Seyfert 1 galaxies and quasars. We have chosen all the active galaxies observed by IUE satellite for the study of luminosity-distance with redshift. The luminosity-distances (D L ) have been calculated using the Hubbles law under non-relativistic and relativistic limits with H0 = 73 Km/sec/Mpc and Terrell (1979) also. We have found that all D L estimations are consistent with each other for z = 1. The results of cosmological calulator I and II are found to consistent with each other and higher by several factors over cosmological calculator IV and the predictions of the Hubble's law under relativistic case. We observe a kind bimodal distributions in D L for z <= 3.5.

  19. EU supports the LHC high-luminosity study

    CERN Multimedia

    CERN Bulletin

    2011-01-01

    The design collision energy and luminosity of the LHC are already at record numbers, making the machine one of the most complex scientific instruments ever built. However, to extend its discovery potential even further, a major upgrade of the LHC will be required around 2020. This will increase its average luminosity by a factor of 5 to 10 beyond its design value. Fifteen worldwide institutions and the European Union are supporting the initial design phase of the project through the HiLumi LHC programme, whose kick-off meeting will take place on 16-18 November.   The CERN team that has successfully built and tested the Short Magnet Coil – a small 40 cm long magnet capable of producing a 12.5 T magnetic field. The upgrade of the LHC will require about 10 years of design, construction and implementation. The new machine configuration will be called “High Luminosity LHC” (HL-LHC). The similarly named “HiLumi LHC” is the EU programme that supports...

  20. Upgrade of the CMS Tracker for High Luminosity Operation

    International Nuclear Information System (INIS)

    Full text: The CMS experiment is one of the four large experiments which are currently carried out at the Large Hadron Collider (LHC) at CERN. The innermost detector system, the so-called tracker, is performing with high efficiency and delivers an important contribution to the reconstruction of the physics processes governing the collision of protons with a center-of-mass energy of 14 TeV. An upgrade of the accelerator is planned around 2020, which will boost the luminosity by a factor of ten and will cause a significant increase of the interaction rate. In turn, this will also increase the number of background interactions which has significant impact on the performance of the system to select interesting events (the trigger) and the tracker. To cope with the larger number of particles per collision, the number of sensor elements in the tracker has to be increased while reducing the overall material budget of the detector system. Furthermore, the lifetime of the current tracker is already limited by the harsh radiation environment in the center of the detector to 10 years of operation at the current design luminosity. For the subsequent operation of a new tracker at high luminosity, entirely new sensor materials are needed, which are able to withstand the tenfold increase in irradiation. The Institute of High Energy Physics (HEPHY) is significantly involved in the research and development of the new CMS tracker for high luminosity operation. This talk will give a short introduction on the main challenges for the new detector, followed by a presentation of the newest developments on silicon strip sensors which are designed and investigated at HEPHY. (author)

  1. KEKB B-Factory, the luminosity frontier

    International Nuclear Information System (INIS)

    The experiment at the KEKB B-Factory, as well as PEP-II, brought the final blow on the 2008 Nobel Prize in Physics for the Kobayashi-Maskawa theory. A few key issues will be described on the design and performance of KEKB to make the world's highest luminosity possible. (author)

  2. RHIC Proton Luminosity and Polarization Improvement

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, S. Y. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-01-17

    The RHIC proton beam polarization can be improved by raising the Booster scraping, which also helps to reduce the RHIC transverse emittance, and therefore to improve the luminosity. By doing this, the beam-beam effect would be enhanced. Currently, the RHIC working point is constrained between 2/3 and 7/10, the 2/3 resonance would affect intensity and luminosity lifetime, and the working point close to 7/10 would enhance polarization decay in store. Run 2013 shows that average polarization decay is merely 1.8% in 8 hours, and most fills have the luminosity lifetime better than 14 hours, which is not a problem. Therefore, even without beam-beam correction, there is room to improve for RHIC polarization and luminosity. The key to push the Booster scraping is to raise the Booster input intensity; for that, two approaches can be used. The first is to extend the LINAC tank 9 pulse width, which has been successfully applied in run 2006. The second is to raise the source temperature, which has been successfully applied in run 2006 and run 2012.

  3. MPX Detectors as LHC Luminosity Monitor

    CERN Document Server

    Sopczak, Andre; Asbah, Nedaa; Bergmann, Benedikt; Bekhouche, Khaled; Caforio, Davide; Campbell, Michael; Heijne, Erik; Leroy, Claude; Lipniacka, Anna; Nessi, Marzio; Pospisil, Stanislav; Seifert, Frank; Solc, Jaroslav; Soueid, Paul; Suk, Michal; Turecek, Daniel; Vykydal, Zdenek

    2015-01-01

    A network of 16 Medipix-2 (MPX) silicon pixel devices was installed in the ATLAS detector cavern at CERN. It was designed to measure the composition and spectral characteristics of the radiation field in the ATLAS experiment and its surroundings. This study demonstrates that the MPX network can also be used as a self-sufficient luminosity monitoring system. The MPX detectors collect data independently of the ATLAS data-recording chain, and thus they provide independent measurements of the bunch-integrated ATLAS/LHC luminosity. In particular, the MPX detectors located close enough to the primary interaction point are used to perform van der Meer calibration scans with high precision. Results from the luminosity monitoring are presented for 2012 data taken at sqrt(s) = 8 TeV proton-proton collisions. The characteristics of the LHC luminosity reduction rate are studied and the effects of beam-beam (burn-off) and beam-gas (single bunch) interactions are evaluated. The systematic variations observed in the MPX lum...

  4. Tracking and Luminosity Calibration of the PLT

    CERN Document Server

    CMS Collaboration

    2015-01-01

    The Pixel Luminosity Telescope (PLT) is one of the newest additions to the CMS detector for the LHC Run II data taking period. On each side of the CMS detector it consists of eight 3-layer telescopes based on silicon pixel detectors that are placed around the beam pipe viewing the interaction point at small angle. A fast 3-fold coincidence of the pixel planes in each telescope provides a bunch-by-bunch measurement of the relative luminosity. In addition to the physics program of CMS, this measurement is useful for accelerator diagnostics and optimization. Particle tracking information sampled at a kHz rate allows collision products to be distinguished from beam background, provides a self-alignment of the detectors, and provides for continuous in-time monitoring of the efficiency of each telescope plane. After calibration of the delivered luminosity in Van der Meer scans of the LHC beam, the PLT is expected to reduce the uncertainty on the delivered luminosity of the LHC which is a crucial input for precision...

  5. The TOPAZ luminosity monitor at KEK

    International Nuclear Information System (INIS)

    The details of the TOPAZ luminosity monitor at KEK are presented. The design concept and construction method are described. Optical fiber was chosen as the material for the light guide because of its flexibility. Results for the performance of counters in electron beam tests are presented. The data acquisition system is also described in detail. (orig.)

  6. Academic Training - LHC luminosity upgrade: detector challenges

    CERN Multimedia

    Françoise Benz

    2006-01-01

    ACADEMIC TRAINING LECTURE SERIES 13, 14, 15, March, from 11:00 to 12:00 - 16 March from 10:00 to 12:00 Main Auditorium, bldg. 500 on 14, 15 March, Council Room on 13, 16 March LHC luminosity upgrade: detector challenges A. De Roeck / CERN-PH, D. Bortoletto / Purdue Univ. USA, R. Wigmans / Texas, Tech Univ. USA, W. Riegler / CERN-PH, W. Smith / Wisconsin Univ. USA The upgrade of the LHC machine towards higher luminosity (1035 cm-2s-1) has been studied over the last few years. These studies have investigated scenarios to achieve the increase in peak luminosity by an order of magnitude, as well as the physics potential of such an upgrade and the impact of a machine upgrade on the LHC DETECTORS. This series of lectures will cover the following topics: Physics motivation and machine scenarios for an order of magnitude increase in the LHC peak luminosity (lecture 1) Detector challenges including overview of ideas for R&D programs by the LHC experiments: tracking and calorimetry, other new detector ...

  7. An asymmetric B factory at 1036 luminosity

    International Nuclear Information System (INIS)

    The physics opportunities at an asymmetric B Factory operating at the unprecedented luminosity of 1036 cm-2 s-1 are unique and attractive. The accelerator appears to be practical and the challenges of performing a sensitive experiment in this environment can be met

  8. LUMINOSITY EVOLUTION OF GAMMA-RAY PULSARS

    International Nuclear Information System (INIS)

    We investigate the electrodynamic structure of a pulsar outer-magnetospheric particle accelerator and the resulting gamma-ray emission. By considering the condition for the accelerator to be self-sustained, we derive how the trans-magnetic-field thickness of the accelerator evolves with the pulsar age. It is found that the thickness is small but increases steadily if the neutron-star envelope is contaminated by sufficient light elements. For such a light element envelope, the gamma-ray luminosity of the accelerator is kept approximately constant as a function of age in the initial 10,000 yr, forming the lower bound of the observed distribution of the gamma-ray luminosity of rotation-powered pulsars. If the envelope consists of only heavy elements, on the other hand, the thickness is greater, but it increases less rapidly than a light element envelope. For such a heavy element envelope, the gamma-ray luminosity decreases relatively rapidly, forming the upper bound of the observed distribution. The gamma-ray luminosity of a general pulsar resides between these two extreme cases, reflecting the envelope composition and the magnetic inclination angle with respect to the rotation axis. The cutoff energy of the primary curvature emission is regulated below several GeV even for young pulsars because the gap thickness, and hence the acceleration electric field, is suppressed by the polarization of the produced pairs.

  9. Luminosity Distributions within Rich Clusters - I: A Ubiquitous Dwarf-Rich Luminosity Function ?

    OpenAIRE

    Smith, Rodney M.; Driver, Simon P; Phillipps, Steven

    1997-01-01

    From deep CCD observations of the cluster Abell 2554 we have recovered the cluster's luminosity distribution over a wide range of magnitude (-24 < M(R) < -16). We compare the derived A2554 cluster luminosity function (at redshift 0.1) with that of the local Coma Cluster (A1656) and the more distant (z = 0.2) cluster A963. The distribution is remarkably similar for these three clusters of comparable richness and morphology. All show a flat (\\alpha = -1.0) luminosity function for the giant gala...

  10. LOW CO LUMINOSITIES IN DWARF GALAXIES

    International Nuclear Information System (INIS)

    We present maps of 12COJ = 2-1 emission covering the entire star-forming disks of 16 nearby dwarf galaxies observed by the IRAM HERACLES survey. The data have 13'' angular resolution, ∼250 pc at our average distance of D = 4 Mpc, and sample the galaxies by 10-1000 resolution elements. We apply stacking techniques to perform the first sensitive search for CO emission in dwarf galaxies outside the Local Group ranging from individual lines of sight, stacking over IR-bright regions of embedded star formation, and stacking over the entire galaxy. We detect five galaxies in CO with total CO luminosities of LCO2-1 = (3-28) × 106 K km s–1 pc2. The other 11 galaxies remain undetected in CO even in the stacked images and have LCO2-1 ∼6 K km s–1 pc2. We combine our sample of dwarf galaxies with a large sample of spiral galaxies from the literature to study scaling relations of LCO with MB and metallicity. We find that dwarf galaxies with metallicities of Z ≈ 1/2-1/10 Z☉ have LCO of 2-4 orders of magnitude smaller than massive spiral galaxies and that their LCO per unit LB is 1-2 orders of magnitude smaller. A comparison with tracers of star formation (FUV and 24 μm) shows that LCO per unit star formation rate (SFR) is 1-2 orders of magnitude smaller in dwarf galaxies. One possible interpretation is that dwarf galaxies form stars much more efficiently: we argue that the low LCO/SFR ratio is due to the fact that the CO-to-H2 conversion factor, αCO, changes significantly in low-metallicity environments. Assuming that a constant H2 depletion time of τdep = 1.8 Gyr holds in dwarf galaxies (as found for a large sample of nearby spirals) implies αCO values for dwarf galaxies with Z ≈ 1/2-1/10 Z☉ that are more than one order of magnitude higher than those found in solar metallicity spiral galaxies. Such a significant increase of αCO at low metallicity is consistent with previous studies, in particular those of Local Group dwarf galaxies that model dust emission to constrain H2 masses. Even though it is difficult to parameterize the dependence of αCO on metallicity given the currently available data, the results suggest that CO is increasingly difficult to detect at lower metallicities. This has direct consequences for the detectability of star-forming galaxies at high redshift, which presumably have on average sub-solar metallicity.

  11. Restriction on the energy and luminosity of e+e- storage rings due to beamstrahlung

    CERN Document Server

    Telnov, V I

    2013-01-01

    It was recently suggested that a 120 x 120 GeV e+e- storage ring for the study of a 125 GeV Higgs boson could be built more simply and cheaply than a linear collider. It was also argued that the "crab waist" collision scheme would allow a storage ring to surpass a linear collider in luminosity up to 2E=500 GeV. We demonstrate that particle loss due to beamstrahlung (synchrotron radiation in beam collisions) reduces beam lifetime at the proposed storage rings to nearly zero. Reasonable beam lifetime can be achieved only at the price of a considerable reduction in luminosity. At 2E=240 GeV, the luminosity may still be sufficient; however, at 2E=400-500 GeV, the luminosity would be a factor 15-25 smaller than desired.

  12. Observations on the luminosity lifetimes, emittance growth rates and intra-beam scattering at the Tevatron

    International Nuclear Information System (INIS)

    A record luminosity of 4.2 1031has been reached at the Fermilab p-(bar p) collider. The lifetime of this luminosity at the beginning of the store is about 10 hours. This lifetime can be explained by the measured loss of anti-protons and protons due to collisions and emittance growths. We report on transverse emittance growth rates based on our Synchrotron Light Monitor. Longitudinal emittance growth rate measurements are based on the TeV Sampled Bunch Display data. It is shown that Intra Beam Scattering is a significant source of emittance growth rates. We comment on other possible factors for these observed emittance growth rates. Finally, we comment on future luminosity lifetimes, as we hope to further increase our peak luminosity

  13. THE SDSS-III BARYON OSCILLATION SPECTROSCOPIC SURVEY: THE QUASAR LUMINOSITY FUNCTION FROM DATA RELEASE NINE

    International Nuclear Information System (INIS)

    We present a new measurement of the optical quasar luminosity function (QLF), using data from the Sloan Digital Sky Survey-III: Baryon Oscillation Spectroscopic Survey (SDSS-III: BOSS). From the SDSS-III Data Release Nine, a uniform sample of 22,301 i ∼2, with confirmed spectroscopic redshifts between 2.2 i (z = 2.2) ≈ –24.5 and see a clear break in the QLF at all redshifts up to z = 3.5. A log-linear relation (in log Φ* – M*) for a luminosity evolution and density evolution model is found to adequately describe our data within the range 2.2 < z < 3.5; across this interval the break luminosity increases by a factor of ∼2.6 while Φ* declines by a factor of ∼8. At z ∼< 2.2 our data are reasonably well fit by a pure luminosity evolution model, and only a weak signature of ''AGN downsizing'' is seen, in line with recent studies of the hard X-ray luminosity function. We compare our measured QLF to a number of theoretical models and find that models making a variety of assumptions about quasar triggering and halo occupation can fit our data over a wide range of redshifts and luminosities

  14. Physics as a function of energy and luminosity

    International Nuclear Information System (INIS)

    In this paper, a new physics in the range of mass up to TeV region is discussed. Most of the discussion concern hadron-hadron (hh) colliders, and also electron-positron colliders are discussed. The cross-sections for new particle production in hh colliders have the general Drell-Yan form, in which the differential luminosity for the collision of partons is included. The formulas with the parton distribution scaled up from present energy using the Altarelli-Parisi equations may be approximately correct within a factor of 2 for the production of particles. Some typical parton-parton luminosity functions for proton-proton and proton-antiproton collisions are presented. From the consideration of luminosity, it can be said that the pp colliders are to be preferred. The case studies of some of the possible new physics discussed by Zakharov, mainly on Higgs bosons and supersymmetric particles, but also a few remarks about technicolor are presented. It seems possible to detect technicolor at a large hh collider. The physics reaches of different possible hh colliders are summarized in tables. In the tables, the observable production of Higgses up to 1 TeV in mass, the observable masses for gluinos (squarks) and the technicolor observability are shown. The cleanliness of electron-positron colliders compared to hadron-hadron colliders is pled, a guess is given as to the appropriate conversion factors between the energy in the electron-positron and hh collisions, the complementarity of electron-positron and hh colliders is urged, and it is argued that a rational mix of world accelerators would include both. (Kato, T.)

  15. Luminosity measurement method for the LHC: Event selection and absolute luminosity determination

    Energy Technology Data Exchange (ETDEWEB)

    Krasny, M.W., E-mail: krasny@lpnhep.in2p3.fr [LPNHE, Pierre and Marie Curie University, CNRS-IN2P3, Tour 33, RdC, 4, pl. Jussieu, 75005 Paris (France); Chwastowski, J. [Institute of Teleinformatics, Faculty of Physics, Mathematics and Computer Science, Cracow University of Technology, ul. Warszawska 24, 31-115 Kraków (Poland); Institute of Nuclear Physics PAN, ul. Radzikowskiego 152, 31-342 Kraków (Poland); Cyz, A.; Słowikowski, K. [Institute of Nuclear Physics PAN, ul. Radzikowskiego 152, 31-342 Kraków (Poland)

    2013-11-21

    In our earlier papers Krasny et al. [1,2] have proposed a new luminosity measurement method which uses lepton pairs produced in peripheral collisions of the LHC beam particles, and identified the requirements for a new, specialized luminosity detector which is indispensable for their efficient on-line selection. In this paper we use the base-line detector model, with no precise timing capabilities, to evaluate the statistical and systematic accuracy of the method. We propose the complete event selection procedure and demonstrate that it allows to collect a sufficiently large sample of e{sup +}e{sup −} pairs to achieve a better than 1% statistical accuracy of the luminosity measurement over less than one-month-long running time intervals. We argue that the absolute luminosity measurement systematic errors can be kept below 1%. The proposed method can be directly applied to the LHC running periods for which the machine instantaneous luminosity does not exceed the L=10{sup 33}s{sup −1}cm{sup −2} value. Two ways extending the method to the large pile-up periods corresponding to higher instantaneous luminosities are proposed.

  16. LIGHT and LUMINOSITY, from Einstein to LHC

    CERN Document Server

    CERN. Geneva; Prof. ROSSI, Lucio

    2015-01-01

    After an introduction on the concept of light in physics, this talk will focus on CERNs High Luminosity LHC project, aiming at extending the discovery potential of CERNs flagship accelerator by increasing its luminosity (ie the number of particles that can be squeezed inside the accelerator to maximize the number of collisions). To achieve this objective, many new technologies are being developed at CERN and many collaborating institutes worldwide, especially in the field of superconductivity. Lucio Rossi, the main speaker, is the head of the HL-LHC project, based at CERN. Giorgio Apollinari, Director for the LHC Accelerator Research Program (LARP) will speak through a videoconference from Fermilab (USA). The event is webcast live and will be followed by Fermilab and other institutes in the USA.

  17. High luminosity muon scattering at FNAL

    International Nuclear Information System (INIS)

    The charge of this group was to evaluate the physics that can be done with a high luminosity μ scattering experiment at FNAL using the upgraded Tevatron muon beam, and consider the apparatus required. In this report, the physics that can be accomplished with a high luminosity μ scattering experiment is evaluated. The CERN and FNAL μ beams are compared in the context of such an experiment. The expected muon flux with the upgraded machine is estimated. Two possible detectors are compared: the air-core toroid experiment proposed by Guyot et al., and an upgraded version of the E665 double-diode apparatus now in place at FNAL. The relative costs of the detectors are considered. A list of detailed questions that need to be answered regarding the double-diode experiment has be compiled. 2 refs., 10 figs., 2 tabs

  18. Shedding Light on the Galaxy Luminosity Function

    CERN Document Server

    Johnston, Russell

    2011-01-01

    From as early as the 1930s, astronomers have tried to quantify the statistical nature of the evolution and large-scale structure of galaxies by studying their luminosity distribution as a function of redshift - known as the galaxy luminosity function (LF). Accurately constructing the LF remains a popular and yet tricky pursuit in modern observational cosmology where the presence of observational selection effects due to e.g. detection thresholds in apparent magnitude, colour, surface brightness or some combination thereof can render any given galaxy survey incomplete and thus introduce bias into the LF. Over the last seventy years there have been numerous sophisticated statistical approaches devised to tackle these issues; all have advantages -- but not one is perfect. This review takes a broad historical look at the key statistical tools that have been developed over this period, discussing their relative merits and highlighting any significant extensions and modifications. In addition, the more generalised ...

  19. A high luminosity bar BB factory

    International Nuclear Information System (INIS)

    In this paper the authors discuss a proposal for the construction of a high luminosity, L ∼ 1034 cm-2 s-1, electron-positron collider, operating in the energy range of 10 to 15 GeV total center of mass energy. The motivation for such a bar B-B system, in particular the rare decay modes and the CP violation. In this paper the authors give only a preliminary estimate of the main parameters of this system, with the purpose of establishing its feasibility. The high luminosity required to study the B physics makes any collider extremely difficult, and pushes the beam characteristics to a region not yet explored. What we propose is no exception and will require a large amount of research and development of beam physics and technology before a more detailed proposal can be made

  20. Solar gravitational energy and luminosity variations

    CERN Document Server

    Fazel, Z; Lefebvre, S; Ajabshirizadeh, A; Pireaux, S; 10.1016/j.newst.2007.05.003

    2009-01-01

    Due to non-homogeneous mass distribution and non-uniform velocity rate inside the Sun, the solar outer shape is distorted in latitude. In this paper, we analyze the consequences of a temporal change in this figure on the luminosity. To do so, we use the Total Solar Irradiance (TSI) as an indicator of luminosity. Considering that most of the authors have explained the largest part of the TSI modulation with magnetic network (spots and faculae) but not the whole, we could set constraints on radius and effective temperature variations (dR, dT). However computations show that the amplitude of solar irradiance modulation is very sensitive to photospheric temperature variations. In order to understand discrepancies between our best fit and recent observations of Livingston et al. (2005), showing no effective surface temperature variation during the solar cycle, we investigated small effective temperature variation in irradiance modeling. We emphasized a phase-shift (correlated or anticorrelated radius and irradianc...

  1. What is L*?: Anatomy of the Galaxy Luminosity Function

    OpenAIRE

    Cooray, Asantha; Milosavljevic, Milos

    2005-01-01

    Using the empirical relations between the central galaxy luminosity and the halo mass, and between the total galaxy luminosity in a halo and the halo mass, we construct the galaxy luminosity function (LF). To the luminosity of the central galaxy in a halo of a given mass we assign log-normal scatter with a mean calibrated against the observations. In halos where the total galaxy luminosity exceeds that of the central galaxy, satellite galaxies are distributed as a power-law in luminosity. Com...

  2. KEKB B-Factory, The Luminosity Frontier

    Science.gov (United States)

    Oide, K.

    2009-07-01

    The experiment at the KEKB B-Factory [KEKB B-Factory Design Report, National Laboratory for High Energy Physics, KEK Report textbf{95-7} (1995)], as well as PEP-II, brought the final blow on the 2008 Nobel Prize in Physics for the Kobayashi-Maskawa theory. A few key issues will be described on the design and performance of KEKB to make the world's highest luminosity possible.

  3. Luminosity criteria for E-SO Galaxies

    International Nuclear Information System (INIS)

    The concept of 'Sequences' of early-type galaxies has been introduced to describe the magnitude Bsub(T) effective radius Asub(e) relation in clusters, according to the definitions and data in the Second Reference Catalogue of Bright Galaxies. For Main Sequence objects, a formula involving the average brightness msub(e) within Asub(e) and the color U-B (or U-V) can be used to estimate relative luminosities and distances of E-SO galaxies

  4. Luminosity of photon-photon colliders

    International Nuclear Information System (INIS)

    By using a Monte Carlo code, we estimated a realistic photon beam profile and luminosity as well as a beam background of the photon-photon collider. We also indicated a possibility of generating higher energy photons exceeding the threshold of e+e- pair creation, which was previously considered to be impossible due to serious background from e+e- pairs created by the collision of the backscattered photon and a laser photon. (author)

  5. Luminosity Measurement at the Large Hadron Collider

    CERN Document Server

    Caron, B L

    2006-01-01

    Two novel methods of measuring the luminosity delivered to the ATLAS Experiment at the CERN Large Hadron Collider experiments are presented. The production of $\\mu^{+}\\mu^{-}$ pair via two photon interactions and single $W^{\\pm}/Z^{0}$ boson production are evaluated as methods for the measurement and monitoring of the proton-proton luminosity at the LHC. The characteristics of the $\\mu^{+}\\mu^{-}$ pairs from coherent $\\gamma \\gamma$ interactions are examined for both matrix element and equivalent photon based monte carlo generators with subsequent simulation of the ATLAS detector effects. The application of specific kinematic and vertex fit requirements is shown to offer a strong method of isolating signal from background and in turn yield an accurate offline measurement of the delivered luminosity via the pure QED process. The choice of kinematic cuts is shown to reduce the overall uncertainty in the method by limiting the size of corrections to the two photon interaction cross section to the level of 1\\%. B...

  6. Luminosity polarization correlation in the SLC

    International Nuclear Information System (INIS)

    In this paper we discuss the correlation between low luminosity and low polarization for off-energy particles in the Stanford Linear Collider (SLC). In the arcs of the SLC the spin of the polarized electrons has a net horizontal precession of about 25 turns. For example, a particle off energy by 1% deviates by 0.25 spin turns or a 90 degrees rotation from the core. It reduces the average polarization measured by a Compton polarimeter near the interaction point (IP)Since the energy acceptance or bandwidth of the final focus optics is limited to a certain range (? 0.5%), these off-energy particles are not focussed as well at the IP and thus contribute less to luminosity. Therefore, the effective polarization at the IP weighted by the luminosity is higher than the measured polarization. Relative corrections of this measured value by +0.5 to 1% for the core and another +1 to 2% for low energy beam tails seems to be necessary for the 1993 run. In 1994, beam shaping with over-compression producing lower energy spreads and smaller tails together with a new arc setup with fewer effective spin turns promise to reduce this effect by an order of magnitude

  7. The luminosity function of the CfA Redshift Survey

    Science.gov (United States)

    Marzke, R. O.; Huchra, J. P.; Geller, M. J.

    1994-01-01

    We use the CfA Reshift Survey of galaxies with m(sub z) less than or equal to 15.5 to calculate the galaxy luminosity function over the range -13 less than or equal to M(sub z) less than or equal to -22. The sample includes 9063 galaxies distributed over 2.1 sr. For galaxies with velocities cz greater or equal to 2500 km per sec, where the effects of peculiar velocities are small, the luminosity function is well represented by a Schechter function with parameters phi(sub star) = 0.04 +/- 0.01 per cu Mpc, M(sub star) = -18.8 +/- 0.3, and alpha = -1.0 +/- 0.2. When we include all galaxies with cz greater or equal to 500 km per sec, the number of galaxies in the range -16 less than or equal to M(sub z) less than or equal to -13 exceeds the extrapolation of the Schechter function by a factor of 3.1 +/- 0.5. This faint-end excess is not caused by the local peculiar velocity field but may be partially explained by small scale errors in the Zwicky magnitudes. Even with a scale error as large as 0.2 mag per mag, which is unlikely, the excess is still a factor of 1.8 +/- 0.3. If real, this excess affects the interpretation of deep counts of field galaxies.

  8. Probing the Ultraviolet Luminosity Function of the Earliest Galaxies with the Renaissance Simulations

    Science.gov (United States)

    O'Shea, Brian W.; Wise, John H.; Xu, Hao; Norman, Michael L.

    2015-07-01

    In this paper, we present the first results from the Renaissance Simulations, a suite of extremely high-resolution and physics-rich AMR calculations of high-redshift galaxy formation performed on the Blue Waters supercomputer. These simulations contain hundreds of well-resolved galaxies at z˜ 25-8, and make several novel, testable predictions. Most critically, we show that the ultraviolet luminosity function of our simulated galaxies is consistent with observations of high-z galaxy populations at the bright end of the luminosity function ({M}1600≤slant -17), but at lower luminosities is essentially flat rather than rising steeply, as has been inferred by Schechter function fits to high-z observations, and has a clearly defined lower limit in UV luminosity. This behavior of the luminosity function is due to two factors: (i) the strong dependence of the star formation rate (SFR) on halo virial mass in our simulated galaxy population, with lower-mass halos having systematically lower SFRs and thus lower UV luminosities; and (ii) the fact that halos with virial masses below ≃ 2× {10}8 {M}⊙ do not universally contain stars, with the fraction of halos containing stars dropping to zero at ≃ 7× {10}6 {M}⊙ . Finally, we show that the brightest of our simulated galaxies may be visible to current and future ultra-deep space-based surveys, particularly if lensed regions are chosen for observation.

  9. The Luminosity and Angular Distributions of Long GRBs

    OpenAIRE

    Guetta, D.; Piran, T.; Waxman, E.

    2003-01-01

    The realization that the total energy of GRBs is correlated with their jet break angles motivates the search for a similar relation between the peak luminosity, $L$, and the jet break angles, $L\\propto\\theta^{-2}$. Such a relation implies that the GRB luminosity function determines the angular distribution. We re-derive the GRB luminosity function using the BATSE peak flux distribution and compare the predicted distribution with the observed redshift distribution. The luminosity function can ...

  10. A fast luminosity monitor system for PEP II

    Energy Technology Data Exchange (ETDEWEB)

    Ecklund, Stan; Field, Clive E-mail: sargon@slac.stanford.edu; Mazaheri, Gholam

    2001-05-01

    The PEP II fast luminosity system provides a measurement of luminosity to the control system with a time constant of 0.3 s and fluctuations less than 0.1% for this interval, adequate for use in feedback systems. Continuous visual updates of luminosity are provided. The alignment of the positron beam at the collision point can also be monitored, and there is a visual display of the luminosity associated with each bunch pair in the machine, sampled approximately every 2 s.

  11. A fast luminosity monitor system for PEP II

    International Nuclear Information System (INIS)

    The PEP II fast luminosity system provides a measurement of luminosity to the control system with a time constant of 0.3 s and fluctuations less than 0.1% for this interval, adequate for use in feedback systems. Continuous visual updates of luminosity are provided. The alignment of the positron beam at the collision point can also be monitored, and there is a visual display of the luminosity associated with each bunch pair in the machine, sampled approximately every 2 s

  12. NLC Luminosity as a Function of Beam Parameters

    CERN Document Server

    Nosochkov, Yu M; Raubenheimer, T O; Seryi, Andrei

    2002-01-01

    Realistic calculation of NLC luminosity has been performed using particle tracking in DIMAD and beam-beam simulations in GUINEA-PIG code for various values of beam emittance, energy and beta functions at the Interaction Point (IP). Results of the simulations are compared with analytic luminosity calculations. The optimum range of IP beta functions for high luminosity was identified.

  13. On the distinction between density and luminosity evolution

    International Nuclear Information System (INIS)

    It is shown that the assumptions of pure density evolution and pure luminosity evolution lead to observable differences in the distribution of sources for all convergent luminosity functions. The proof given is valid for sources with an arbitrary number of intrinisic luminosities (e.g., optical, infrared, and radio) and also holds in the special cases of mixed evolution that are considered. (author)

  14. CLOC: Cluster Luminosity Order-Statistic Code

    Science.gov (United States)

    Da Silva, Robert L.; Krumholz, Mark R.; Fumagalli, Michele; Fall, S. Michael

    2016-02-01

    CLOC computes cluster order statistics, i.e. the luminosity distribution of the Nth most luminous cluster in a population. It is flexible and requires few assumptions, allowing for parametrized variations in the initial cluster mass function and its upper and lower cutoffs, variations in the cluster age distribution, stellar evolution and dust extinction, as well as observational uncertainties in both the properties of star clusters and their underlying host galaxies. It uses Markov chain Monte Carlo methods to search parameter space to find best-fitting values for the parameters describing cluster formation and disruption, and to obtain rigorous confidence intervals on the inferred values.

  15. Lenticular Galaxy Formation - Possible Luminosity Dependence

    OpenAIRE

    Barway, Sudhanshu; Kembhavi, Ajit; Wadadekar, Yogesh; Ravikumar, C. D.; Mayya, Y. D.

    2007-01-01

    We investigate the correlation between the bulge effective radius (r_e) and disk scale length (r_d), in the near-infrared K band for lenticular galaxies in the field and in clusters. We find markedly different relations between the two parameters as a function of luminosity. Lenticulars with total absolute magnitude fainter than M_T = -24.5 show a positive correlation, in line with predictions of secular formation processes for the pseudo bulges of late-type disk galaxies. But brighter lentic...

  16. Galaxy luminosity function: a new analytic expression

    Scientific Electronic Library Online (English)

    J. S., Alcaniz; J. A. S., Lima.

    2004-06-01

    Full Text Available We propose a new analytic approximation for the luminosity function of galaxies. The suggested expression behaves like the Schechter function at the faint end (f ~ La) but departs considerably at the bright end (L >> L*). We argue here that such a behavior may provide a better fit for the current ob [...] servational data than does the Schechter function. Its practical interest is stressed by considering roughly the data set provided by the Stromlo-APM redshift survey. Implications on the estimates of the matter density parameter from mass-to-light ratio are also briefly discussed.

  17. New evidence for galaxy luminosity evolution

    International Nuclear Information System (INIS)

    Near-infrared photometry for 61 elliptical galaxies is used with previously published data to demonstrate that little or no color evolution is observed at infrared wavelengths, while galaxies near z = 1 are brighter than those at low redshift. Optically selected galaxies are compared with radio galaxies, and no differences in infrared properties are found. Evolution of a stellar population with an initial mass function similar to that observed in the solar neighborhood coupled with a value for q0 near 0.5 provides the best fit to the color and luminosity data

  18. Luminosity measurement at the Large Hadron Collider

    Science.gov (United States)

    Caron, Bryan Lawrence

    Two novel methods of measuring the luminosity delivered to the ATLAS Experiment at the CERN Large Hadron Collider experiments are presented. The production of mu+mu- pair via two photon interactions and single W+/-/ Z0 boson production are evaluated as methods for the measurement and monitoring of the proton-proton luminosity at the LHC. The characteristics of the mu+mu- pairs from coherent gammagamma interactions are examined for both matrix element and equivalent photon based Monte Carlo generators with subsequent simulation of the ATLAS detector effects. The application of specific kinematic and vertex fit requirements is shown to offer a strong method of isolating signal from background and in turn yield an accurate offline measurement of the delivered luminosity via the pure QED process. The choice of kinematic cuts is shown to reduce the overall uncertainty in the method by limiting the size of corrections to the two photon interaction cross section to the level of 1%. Based upon these developed criteria, the results of a first search for the exclusive production of mu+mu- events from two photon interactions at CDF and the Fermilab Tevatron are presented, providing preliminary evidence for the first observation of two photon process at a hadron collider. The observation of single gauge boson production is also reviewed as a promising method for online luminosity monitoring at the LHC. The theoretical and experimental considerations are examined. Event selection criteria, efficiencies and rates are outlined based upon the trigger conditions of the ATLAS experiment. The combined effect of recent theoretical developments in the computation of higher order QCD corrections and parton distribution function (PDF) error sets are incorporated into simulation studies performed for the LHC. An implementation of new PDF reweighting method by which it is possible to calculate the effective uncertainty on physically measurable quantities, without requiring the repeated simulation of identical events with separate PDF error sets as input, is described. The error in acceptance for the observation of Z0 ? e+e - due to the most recent CTEQ PDF error set is shown to be less than 1%.

  19. THE SDSS-III BARYON OSCILLATION SPECTROSCOPIC SURVEY: THE QUASAR LUMINOSITY FUNCTION FROM DATA RELEASE NINE

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Nicholas P.; White, Martin; Bailey, Stephen [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 92420 (United States); McGreer, Ian D. [Steward Observatory, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Richards, Gordon T. [Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Myers, Adam D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Palanque-Delabrouille, Nathalie; Yeche, Christophe [CEA, Centre de Saclay, IRFU, F-91191 Gif-sur-Yvette (France); Strauss, Michael A. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Anderson, Scott F. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Shen, Yue; Swanson, Molly E. C. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Brandt, W. N. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Aubourg, Eric [APC, University of Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cite (France); Bizyaev, Dmitry; Brewington, Howard; Brinkmann, J. [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349-0059 (United States); Bovy, Jo [Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States); DeGraf, Colin; Di Matteo, Tiziana, E-mail: npross@lbl.gov [McWilliams Center for Cosmology, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); and others

    2013-08-10

    We present a new measurement of the optical quasar luminosity function (QLF), using data from the Sloan Digital Sky Survey-III: Baryon Oscillation Spectroscopic Survey (SDSS-III: BOSS). From the SDSS-III Data Release Nine, a uniform sample of 22,301 i {approx}< 21.8 quasars are selected over an area of 2236 deg{sup 2}, with confirmed spectroscopic redshifts between 2.2 < z < 3.5, filling in a key part of the luminosity-redshift plane for optical quasar studies. The completeness of the survey is derived through simulated quasar photometry, and this completeness estimate is checked using a sample of quasars selected by their photometric variability within the BOSS footprint. We investigate the level of systematics associated with our quasar sample using the simulations, in the process generating color-redshift relations and a new quasar K-correction. We probe the faint end of the QLF to M{sub i} (z = 2.2) Almost-Equal-To -24.5 and see a clear break in the QLF at all redshifts up to z = 3.5. A log-linear relation (in log {Phi}* - M*) for a luminosity evolution and density evolution model is found to adequately describe our data within the range 2.2 < z < 3.5; across this interval the break luminosity increases by a factor of {approx}2.6 while {Phi}* declines by a factor of {approx}8. At z {approx}< 2.2 our data are reasonably well fit by a pure luminosity evolution model, and only a weak signature of ''AGN downsizing'' is seen, in line with recent studies of the hard X-ray luminosity function. We compare our measured QLF to a number of theoretical models and find that models making a variety of assumptions about quasar triggering and halo occupation can fit our data over a wide range of redshifts and luminosities.

  20. Protostellar Luminosity Functions in 11 Diverse Star Forming Environments

    Science.gov (United States)

    Kryukova, Erin; Megeath, S. T.; Gutermuth, R.; Pipher, J.; Allen, T. S.; Allen, L. E.; Myers, P. C.; Muzerolle, J.; Cygnus-X Legacy Team

    2012-01-01

    Protostars exist in a variety of environments, ranging from clouds with dispersed low-mass stars, such as Taurus, to clustered regions in clouds forming high-mass stars, like Orion. The effect these different environments have on protostar properties such as mass or luminosity is uncertain. One way to probe the effects of cloud environment on the observable property, protostar luminosity is to compare protostellar luminosity functions of clouds hosting varied populations of protostars. In this dissertation talk I will discuss the protostellar luminosity functions from 11 star forming clouds including Lupus, Chamaeleon, Ophiuchus, Perseus, Serpens, Orion, Cep OB3, Mon R2, Cygnus-X, and Maddalena's Cloud, which encompass a wide range of star forming environments. The luminosity functions are constructed from Spitzer surveys of these molecular clouds. I employ a new technique for estimating the bolometric luminosity from near and mid-IR fluxes alone and for subtracting contamination from galaxies, reddened pre-main sequence stars with disks, and edge-on disk systems. The clouds which are forming massive stars show a significant peak at low luminosity and a tail extending toward luminosities above 10 solar luminosities, while the luminosity functions of clouds which are not forming massive stars have no significant peak down to the sensitivity limit and do not exhibit the tail. I compare these luminosity functions to existing models of protostellar evolution. I also compare the luminosity functions of protostars in distributed and clustered environments, as determined using nearest-neighbor distances. In Orion and Cygnus-X, the clouds which contain the largest populations of protostars there is a clear difference in luminosity functions between protostars incrowded and distributed regions, with the luminosity function biased towards higher luminosities in more luminous regions. I will discuss the implications of these variations and the possibility that the IMF is varying within the star forming regions.

  1. The Mid-Infrared Color-Luminosity Relation and the Local 12 micron Luminosity Function

    OpenAIRE

    Fang, Fan; Shupe, David L.; Xu, Cong; Hacking, Perry B.

    1998-01-01

    We have established a model to systematically estimate the contribution of the mid-infrared emission features between 3 and 11.6 micron to the IRAS in-band fluxes, using the results of ISO PHT-S observation of 16 galaxies by Lu et al. (1997). The model is used to estimate more properly the k-corrections for calculating the restframe 12 and 25 micron fluxes and luminosities of IRAS galaxies. We have studied the 12-25 micron color-luminosity relation for a sample of galaxies selected at 25 micr...

  2. CORRELATION BETWEEN GROUP LOCAL DENSITY AND GROUP LUMINOSITY

    International Nuclear Information System (INIS)

    In this study, we investigate the correlation between group local number density and total luminosity of groups. In four volume-limited group catalogs, we can conclude that groups with high luminosity exist preferentially in high-density regions, while groups with low luminosity are located preferentially in low-density regions, and that in a volume-limited group sample with absolute magnitude limit Mr = –18, the correlation between group local number density and total luminosity of groups is the weakest. These results basically are consistent with the environmental dependence of galaxy luminosity.

  3. Luminosity function of the brightest galaxies in the IRAS survey

    International Nuclear Information System (INIS)

    Results from a study of the far infrared properties of the brightest galaxies in the IRAS survey are described. There is a correlation between the infrared luminosity and the infrared to optical luminosity ratio and between the infrared luminosity and the far infrared color temperature in these galaxies. The infrared bright galaxies represent a significant component of extragalactic objects in the local universe, being comparable in space density to the Seyferts, optically identified starburst galaxies, and more numerous than quasars at the same bolometric luminosity. The far infrared luminosity in the local universe is approximately 25% of the starlight output in the same volume

  4. Relation between the X-ray and Optical Luminosities in Binary Systems with Accreting Nonmagnetic White Dwarfs

    CERN Document Server

    Revnivtsev, M G; Suleimanov, V F

    2014-01-01

    We investigate the relation between the optical (g-band) and X-ray (0.5-10 keV) luminosities of accreting nonmagnetic white dwarfs. According to the present-day counts of the populations of star systems in our Galaxy, these systems have the highest space density among the close binary systems with white dwarfs. We show that the dependence of the optical luminosity of accreting white dwarfs on their X-ray luminosity forms a fairly narrow one-parameter curve. The typical half-width of this curve does not exceed 0.2-0.3 dex in optical and X-ray luminosities, which is essentially consistent with the amplitude of the aperiodic flux variability for these objects. At X-ray luminosities Lx~1e32 erg/sec or lower, the optical g-band luminosity of the accretion flow is shown to be related to its X-ray luminosity by a factor ~2-3. At even lower X-ray luminosities (Lx~1e30 erg/sec), the contribution from the photosphere of the white dwarf begins to dominate in the optical spectrum of the binary system and its optical brig...

  5. LHC Report: A new luminosity record

    CERN Multimedia

    CERN Bulletin

    2011-01-01

    After about one month of operation, the LHC has already accumulated an integrated luminosity of 28 pb-1, which corresponds to over 50% of the total delivered to the experiments in 2010. This impressive start to the LHC run in 2011 bodes well for the rest of year.   Following careful collimator set-up and validation, the first phase of beam commissioning 2011 has come to an end. The first stable beams were declared on Sunday 13 March with a moderate 3 bunches per beam and an initial luminosity of 1.6 × 1030 cm-2s-1. Machine protection tests continued during the following week as the commissioning team made absolutely sure that all critical systems (beam dumps, beam interlock system, etc.) were functioning properly. When these tests had finished, the way was opened to increased intensity and the LHC quickly moved through the first part of its planned, staged intensity increase. Fills with increasing numbers of bunches were delivered to the experiments, culminating in a fill with 200...

  6. Selected issues for the LHC luminosity upgrade

    International Nuclear Information System (INIS)

    The Large Hadron Collider started its operations on September 10. 2008. In a realistic forecast it is supposed to demonstrate (or confute) the existence of the Higgs boson for the year 2014. After this date the physics of rare events will be explored more in details and an upgrade of the luminosity can make an important difference in the program of experiments at CERN. This thesis proposes several ideas to increase the luminosity of ATLAS and CMS experiments and the acceptance of TOTEM experiment. The main object of study is the Interaction Region, that consists in the set of magnets in charge to provide the final beam focalization for the collisions. The Interaction Region is studied with the methods of beam optics and beam dynamics to design new layouts for the upgrade. These layouts are also explored from the point of view of integrability in the existing experiments developing the analysis of energy deposition and misalignment tolerances. This study was performed with the use of analytical methods for the general considerations and numerical methods for the parameters optimization. (author)

  7. Jet Cleansing: Pileup Removal at High Luminosity

    CERN Document Server

    Krohn, David; Schwartz, Matthew D; Wang, Lian-Tao

    2013-01-01

    One of the greatest impediments to extracting useful information from high luminosity hadron-collider data is radiation from secondary collisions (i.e. pileup) which can overlap with that of the primary interaction. In this paper we introduce a simple jet-substructure technique termed cleansing which can consistently correct for large amounts of pileup in an observable independent way. Cleansing works at the subjet level, combining tracker and calorimeter-based data to reconstruct the pileup-free primary interaction. The technique can be used on its own, with various degrees of sophistication, or in concert with jet grooming. We apply cleansing to both kinematic and jet shape reconstruction, finding in all cases a marked improvement over previous methods both in the correlation of the cleansed data with uncontaminated results and in measures like S/rt(B). Cleansing should improve the sensitivity of new-physics searches at high luminosity and could also aid in the comparison of precision QCD calculations to co...

  8. Low EUV Luminosities Impinging on Protoplanetary Disks

    CERN Document Server

    Pascucci, I; Gorti, U; Hollenbach, D; Hendler, N P; Brooks, K J; Contreras, Y

    2014-01-01

    The amount of high-energy stellar radiation reaching the surface of protoplanetary disks is essential to determine their chemistry and physical evolution. Here, we use millimetric and centimetric radio data to constrain the EUV luminosity impinging on 14 disks around young (~2-10Myr) sun-like stars. For each object we identify the long-wavelength emission in excess to the dust thermal emission, attribute that to free-free disk emission, and thereby compute an upper limit to the EUV reaching the disk. We find upper limits lower than 10$^{42}$ photons/s for all sources without jets and lower than $5 \\times 10^{40}$ photons/s for the three older sources in our sample. These latter values are low for EUV-driven photoevaporation alone to clear out protoplanetary material in the timescale inferred by observations. In addition, our EUV upper limits are too low to reproduce the [NeII] 12.81 micron luminosities from three disks with slow [NeII]-detected winds. This indicates that the [NeII] line in these sources prima...

  9. Quantifying the Luminosity Evolution in Gamma-ray Bursts

    CERN Document Server

    Kocevski, D; Kocevski, Daniel; Liang, Edison

    2006-01-01

    We estimate the luminosity evolution and formation rate for over 900 GRBs by using redshift and luminosity data calculated by Band, Norris, $&$ Bonnell (2004) via the lag-luminosity correlation. By applying maximum likelihood techniques, we are able to infer the true distribution of the parent GRB population's luminosity function and density distributions in a way that accounts for detector selection effects. We find that after accounting for data truncation, there still exists a significant correlation between the average luminosity and redshift, indicating that distant GRBs are on average more luminous than nearby counterparts. This is consistent with previous studies showing strong source evolution and also recent observations of under luminous nearby GRBs. We find no evidence for beaming angle evolution in the current sample of GRBs with known redshift, suggesting that this increase in luminosity can not be due to an evolution of the collimation of gamma-ray emission. The resulting luminosity function...

  10. The low-luminosity end of the radius-luminosity relationship for active galactic nuclei

    DEFF Research Database (Denmark)

    Bentz, M.C.; Denney, K.D.; Vestergaard, Marianne; Grier, C.J.; Peterson, B.M.; De Rosa, G.; Pogge, R.W.; Barth, A.J.; Bennert, V.N.; Canalizo, G.; Filippenko, A.V.; Li, W.; Gates, E.L.; Greene, J.E.; Malkan, M.A.; Stern, D.; Treu, T.; Woo, J.-H.

    2013-01-01

    the Hubble Space Telescope Wide Field Camera 3. The surface brightness decompositions allow us to create "AGN-free" images of the galaxies, from which we measure the starlight contribution to the optical luminosity measured through the ground-based spectroscopic aperture. We also incorporate 20 new...

  11. INFRARED CLASSIFICATION AND LUMINOSITIES FOR DUSTY ACTIVE GALACTIC NUCLEI AND THE MOST LUMINOUS QUASARS

    International Nuclear Information System (INIS)

    Mid-infrared spectroscopic measurements from the Infrared Spectrometer (IRS) on Spitzer are given for 125 hard X-ray active galactic nuclei (AGNs; 14-195 keV) from the Swift Burst Alert Telescope (BAT) sample and for 32 AGNs with black hole masses (BHMs) from reverberation mapping. The 9.7 μm silicate feature in emission or absorption defines an infrared AGN classification describing whether AGNs are observed through dust clouds, indicating that 55% of the BAT AGNs are observed through dust. The mid-infrared dust continuum luminosity is shown to be an excellent indicator of intrinsic AGN luminosity, scaling closely with the hard X-ray luminosity, log νLν(7.8 μm)/L(X) = –0.31 ± 0.35, and independent of classification determined from silicate emission or absorption. Dust luminosity scales closely with BHM, log νLν(7.8 μm) = (37.2 ± 0.5) + 0.87 log BHM for luminosity in erg s–1 and BHM in M☉. The 100 most luminous type 1 quasars as measured in νLν(7.8 μm) are found by comparing Sloan Digital Sky Survey (SDSS) optically discovered quasars with photometry at 22 μm from the Wide-Field Infrared Survey Explorer (WISE), scaled to rest frame 7.8 μm using an empirical template determined from IRS spectra. The most luminous SDSS/WISE quasars have the same maximum infrared luminosities for all 1.5 IR = 1014.4 L☉. Comparing with dust-obscured galaxies from Spitzer and WISE surveys, we find no evidence of hyperluminous obscured quasars whose maximum infrared luminosities exceed the maximum infrared luminosities of optically discovered quasars. Bolometric luminosities Lbol estimated from rest-frame optical or ultraviolet luminosities are compared to LIR. For the local AGN, the median log LIR/Lbol = –0.35, consistent with a covering factor of 45% for the absorbing dust clouds. For the SDSS/WISE quasars, the median log LIR/Lbol = 0.1, with extremes indicating that ultraviolet-derived Lbol can be seriously underestimated even for type 1 quasars.

  12. Operation of the Run IIB D0 Luminosity System and Determination of the Run IIB Luminosity Constant

    Energy Technology Data Exchange (ETDEWEB)

    Prewitt, Michelle Victoria; /Rice U.

    2010-04-01

    The luminosity system is an integral part of the D0 detector that must be properly maintained to provide accurate luminosity measurements for physics analysis. After the addition of a readout layer to the silicon vertex detector in 2006, it was necessary to re-calculate the effective inelastic cross section to which the luminosity monitor is sensitive. The preliminary analysis showed that the luminosity constant did not change with the addition of the extra layer of silicon. A full study of the revised luminosity constant including a complete analysis of systematic uncertainties has been completed. The luminosity constant was determined to be {sigma}{sub eff} = 48.3 {+-} 1.9 {+-} 0.6 mb, which reduces the D0 contribution to the luminosity measurement uncertainty by almost 3%.

  13. Cryogenic Test of Double Quarter Wave Crab Cavity for the LHC High Luminosity Upgrade

    CERN Document Server

    Xiao, B; Belomestnykh, S; Ben-Zvi, I; Calaga, Rama; Cullen, C; Capatina, Ofelia; Hammons, L; Li, Z; Marques, C; Skaritka, J; Verdú-Andres, S; Wu, Q

    2015-01-01

    A Proof-of-Principle (PoP) Double Quarter Wave Crab Cavity (DQWCC) was designed and fabricated for the Large Hadron Collider (LHC) luminosity upgrade. A vertical cryogenic test has been done at Brookhaven National Lab (BNL). The cavity achieved 4.5 MV deflecting voltage with a quality factor above 3×109 . We report the test results of this design.

  14. Cryogenic test of double quarter wave crab cavity for the LHC High luminosity upgrade

    International Nuclear Information System (INIS)

    A Proof-of-Principle (PoP) Double Quarter Wave Crab Cavity (DQWCC) was designed and fabricated for the Large Hadron Collider (LHC) luminosity upgrade. A vertical cryogenic test has been done at Brookhaven National Lab (BNL). The cavity achieved 4.5 MV deflecting voltage with a quality factor above 3@@109. We report the test results of this design.

  15. Determination of the integrated luminosity at HERA using elastic QED Compton events

    Czech Academy of Sciences Publication Activity Database

    Aaron, F.D.; Alexa, C.; Andreev, V.; Cvach, Jaroslav; Reimer, Petr; Zálešák, Jaroslav

    2012-01-01

    Roč. 72, č. 10 (2012), 1-13. ISSN 1434-6044 R&D Projects: GA MŠk LA09042; GA MŠk LC527 Institutional research plan: CEZ:AV0Z10100502 Keywords : Compton scattering * luminosity Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 5.247, year: 2012

  16. 60 micron luminosity evolution of rich clusters of galaxies

    Science.gov (United States)

    Kelly, Douglas M.; Rieke, George H.

    1990-01-01

    The average 60-micron flux has been determined for a collection of optically selected galaxy clusters at redshifts ranging from 0.30 to 0.92. The result, 26 mJy per cluster, represents the faintest flux determination known of using the IRAS data base. The flux from this set of clusters has been compared to the 60-micron flux from a sample of nearby galaxy clusters. It is found that the far-infrared luminosity evolution in cluster galaxies can be no more than a factor of 1.7 from z = 0.4 to the present epoch. This upper limit is close to the evolution predicted for simple aging of the stellar populations. Additional processes such as mergers, cannibalism, or enhanced rates of starbursts appear to occur at a low enough level that they have little influence on the far-infrared emission from clusters over this redshift range.

  17. 60 micron luminosity evolution of rich clusters of galaxies

    International Nuclear Information System (INIS)

    The average 60-micron flux has been determined for a collection of optically selected galaxy clusters at redshifts ranging from 0.30 to 0.92. The result, 26 mJy per cluster, represents the faintest flux determination known of using the IRAS data base. The flux from this set of clusters has been compared to the 60-micron flux from a sample of nearby galaxy clusters. It is found that the far-infrared luminosity evolution in cluster galaxies can be no more than a factor of 1.7 from z = 0.4 to the present epoch. This upper limit is close to the evolution predicted for simple aging of the stellar populations. Additional processes such as mergers, cannibalism, or enhanced rates of starbursts appear to occur at a low enough level that they have little influence on the far-infrared emission from clusters over this redshift range. 38 refs

  18. Upgrade of RHIC Vacuum Systems for High Luminosity Operation

    CERN Document Server

    Hseuh Hsiao Chaun; Smart, Loralie; Todd, Robert J; Weiss, Daniel

    2005-01-01

    With increasing ion beam intensity during recent RHIC operations, pressure rises of several decades were observed at most room temperature sections and at a few cold sections. The pressure rises are associated with electron multi-pacting, electron stimulated desorption and beam ion induced desorption and have been one of the major intensity and luminosity limiting factors for RHIC. Improvement of the warm sections has been carried out in the last few years. Extensive in-situ bakes, additional UHV pumping, anti-grazing ridges and beam tube solenoids have been implemented. Several hundred meters of NEG coated beam pipes have been installed and activated. Vacuum monitoring and interlock were enhanced to reduce premature beam aborts. Preliminary measures, such as pumping before cool down to reduce monolayer condensates, were also taken to suppress the pressure rises in the cold sections. The effectiveness of these measures in reducing the pressure rises during machine studies and during physics runs are discussed...

  19. Disruption and luminosity of flat beams

    International Nuclear Information System (INIS)

    It has been suggested (ref.1) that high energy linear colliders might operate with non-round beam profiles, i.e. with different sigma/sub x/ and sigma/sub y/, described by an aspect ratio R = sigma/sub y/sigma/sub x/. The advantage of flat beams is the expectation, that ''beamstrahlung'', i.e., beam-beam synchrotron radiation is reduced with increasing R. The reason for this reduction comes from the fact that for constant bunch area and therefore constant luminosity the mean physical distance between the particles increases with R. When the physical distances are larger, the electromagnetic fields and therefore particle acceleration and radiation decrease. This would be of particular importance for very large linear colliders (VLC), where beamstrahlung may consume an appreciable fraction of the incident energy. The underlying assumption is that the emittance quality can be preserved in the deformed bunch. 4 refs., 3 figs., 3 tabs

  20. The metallicity-luminosity relation at medium redshift based on faint CADIS emission line galaxies

    CERN Document Server

    Maier, C; Hippelein, H

    2004-01-01

    The emission line survey within the Calar Alto Deep Imaging Survey (CADIS) detects galaxies with very low continuum brightness by using an imaging Fabry-Perot interferometer. With spectroscopic follow-up observations of MB>~-19 CADIS galaxies using FORS2 at the VLT and DOLORES at TNG we obtained oxygen abundances of 5 galaxies at z~0.4 and 10 galaxies at z~0.64. Combining these measurements with published oxygen abundances of galaxies with MB<~-19 we find evidence that a metallicity-luminosity relation exists at medium redshift, but it is displaced to lower abundances and higher luminosities compared to the metallicity-luminosity relation in the local universe. Comparing the observed metallicities and luminosities of galaxies at z<3 with Pegase2 chemical evolution models we have found a favoured scenario in which the metallicity of galaxies increases by a factor of ~2 between z~0.7 and today, and their luminosity decreases by ~0.5-0.9mag.

  1. Superconducting Quadrupole Prototype for the ISR high luminosity (low beta) insertion

    CERN Multimedia

    1977-01-01

    In colliders, smaller beam cross-section means higher luminosity. Beam-size being proportional to the square-root of the "beta function" value, a small beta means small beam size, hence high luminosity. In 1973 a study was launched on low-beta insertions using superconducting quadrupole magnets, which focus beams to very small sizes at the beam crossing points . In 1976 the first prototype of a superconducting quadrupole was tested. Here we see Theodor Tortschanoff with the prototype of 1.25 m magnetic length. Manufacture of 8 quadrupoles (4 of L=1.15 m, 4 of L=0.65 m) began at Alsthom in 1978. They were installed at intersection I8 of the ISR, enhancing luminosity there by a factor 7 until final low-beta operation in December 1983. For details see "Yellow Report" CERN 76-16. See also pictures 7702307, 7702308, 7702182,7510214X,7510217X.

  2. Redshift modifications to HEAO A-1 cluster X-ray luminosities

    Science.gov (United States)

    Cruddace, R. G.; Kowalski, M. P.; Ulmer, M. P.

    1983-01-01

    New redshift measurements for the 24 Abell galactic clusters are presented. The optical observations are described and applied to the cluster X-ray luminosity function, and the results are used to delimit the cluster contribution to the diffuse X-ray background (DXRB). The evolution of the X-ray luminosity function is then investigated. It is found that while simple two-parameter analytic forms do not fit this function very well, three-parameter forms such as the exponential times power law do fit it very well. Future redshift observations will probably not change the volume emissivity significantly, but they may in a statistically significant way affect the parameters of analytic fits which define the shape of the luminosity function. The contribution of rich clusters to the DXRB in the 2-6 keV range is 5.2 percent. Future redshift observations will modify this result by no more than a factor of about 1.1.

  3. Evolution of cluster X-ray luminosities and radii: Results from the 160 square degree rosat survey

    DEFF Research Database (Denmark)

    Vikhlinin, A.; McNamara, B.R.; Forman, W.; Jones, C.; Quintana, H.; Hornstrup, Allan

    1998-01-01

    -X > 3 x 10(44) ergs s(-1) in the 0.5-2 keV band. We detect a factor of 3-4 deficit of such luminous clusters at z > 0.3 compared with the present. The evolution is much weaker or absent at modestly lower luminosities, (1-3) x 10(44) ergs s(-1). At still lower luminosities, we find no evolution from the...

  4. Observed luminosity difference between isolated and binary MSPs

    CERN Document Server

    Lommen, A N; Nice, D J; Splaver, E M; Stairs, I H; Backer, D C

    2007-01-01

    We perform a brief census of velocities of isolated versus binary millisecond pulsars. We find the velocities of the two populations are indistinguishable. However, the scale height of the binary population is twice that of the isolated population and the luminosity functions of the two populations are different. We suggest that the scale height difference may be an artifact of the luminosity difference. We examine the magnetic fields of the two populations as a possible source of the luminosity difference.

  5. Standardization of CDF and D OE reported luminosities

    International Nuclear Information System (INIS)

    During FNAL collider store 5094, CDF- and D OE modified the computation of their reported luminosities to utilize a standardized world average inelastic cross-section. The changes made at each experiment and in the Accelerator Division are detailed below. A net decrease was expected and was observed for the reported instantaneous luminosity from each experiment. These changes affect the estimates of instantaneous and integrated luminosities reported to the Accelerator Division for the purposes of operational coordination

  6. Seeking the Epoch of Maximum Luminosity for Dusty Quasars

    OpenAIRE

    Vardanyan, Valeri; Weedman, Daniel; Sargsyan, Lusine

    2014-01-01

    Infrared luminosities vLv(7.8 um) arising from dust reradiation are determined for Sloan Digital Sky Survey (SDSS) quasars with 1.4 ~ 3 with maximum luminosity vLv(7.8 um) >~ 10^{47} erg per s; luminosity functions show one quasar per cubic Gpc having vLv(7.8 um) > 10^{46.6} erg per s for all 2 < z < 5. We conclude that the ...

  7. CMS Luminosity Measurement for the 2015 Data Taking Period

    CERN Document Server

    CMS Collaboration

    2016-01-01

    The measurement of the integrated luminosity delivered to the CMS Experiment during the 2015 LHC proton-proton run at $13~\\mathrm{TeV}$ center-of-mass energy is presented. The Pixel Cluster Counting method is used and the absolute luminosity scale calibration is derived from an analysis of Van der Meer Scans performed in August 2015. The overall uncertainty on the luminosity measurement is estimated to be $2.7\\%$.

  8. THE LOW-LUMINOSITY END OF THE RADIUS-LUMINOSITY RELATIONSHIP FOR ACTIVE GALACTIC NUCLEI

    International Nuclear Information System (INIS)

    We present an updated and revised analysis of the relationship between the H? broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositions of the host galaxies of nine new AGNs imaged with the Hubble Space Telescope Wide Field Camera 3. The surface brightness decompositions allow us to create ''AGN-free'' images of the galaxies, from which we measure the starlight contribution to the optical luminosity measured through the ground-based spectroscopic aperture. We also incorporate 20 new reverberation-mapping measurements of the H? time lag, which is assumed to yield the average H? BLR radius. The final sample includes 41 AGNs covering four orders of magnitude in luminosity. The additions and updates incorporated here primarily affect the low-luminosity end of the RBLR-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of ?= 0.533+0.035-0.033, consistent with previous work and with simple photoionization arguments. Only two AGNs appear to be outliers from the relationship, but both of them have monitoring light curves that raise doubt regarding the accuracy of their reported time lags. The scatter around the relationship is found to be 0.19 0.02 dex, but would be decreased to 0.13 dex by the removal of these two suspect measurements. A large fraction of the remaining scatter in the relationship is likely due to the inaccurate distances to the AGN host galaxies. Our results help support the possibility that the RBLR-L relationship could potentially be used to turn the BLRs of AGNs into standardizable candles. This would allow the cosmological expansion of the universe to be probed by a separate population of objects, and over a larger range of redshifts.

  9. THE LOW-LUMINOSITY END OF THE RADIUS-LUMINOSITY RELATIONSHIP FOR ACTIVE GALACTIC NUCLEI

    Energy Technology Data Exchange (ETDEWEB)

    Bentz, Misty C. [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States); Denney, Kelly D.; Vestergaard, Marianne [Dark Cosmology Center, Niels Bohr Institute, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark); Grier, Catherine J.; Peterson, Bradley M.; De Rosa, Gisella; Pogge, Richard W. [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Barth, Aaron J. [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA 92697 (United States); Bennert, Vardha N. [Physics Department, California Polytechnic State University, San Luis Obispo, CA 93407 (United States); Canalizo, Gabriela [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Filippenko, Alexei V.; Li Weidong [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); Gates, Elinor L. [University of California Observatories/Lick Observatory, P.O. Box 85, Mount Hamilton, CA 95140 (United States); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Peyton Hall - Ivy Lane, Princeton, NJ 08544 (United States); Malkan, Matthew A. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Treu, Tommaso [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Woo, Jong-Hak, E-mail: bentz@chara.gsu.edu [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul (Korea, Republic of)

    2013-04-20

    We present an updated and revised analysis of the relationship between the H{beta} broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositions of the host galaxies of nine new AGNs imaged with the Hubble Space Telescope Wide Field Camera 3. The surface brightness decompositions allow us to create ''AGN-free'' images of the galaxies, from which we measure the starlight contribution to the optical luminosity measured through the ground-based spectroscopic aperture. We also incorporate 20 new reverberation-mapping measurements of the H{beta} time lag, which is assumed to yield the average H{beta} BLR radius. The final sample includes 41 AGNs covering four orders of magnitude in luminosity. The additions and updates incorporated here primarily affect the low-luminosity end of the R{sub BLR}-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of {alpha}= 0.533{sup +0.035}{sub -0.033}, consistent with previous work and with simple photoionization arguments. Only two AGNs appear to be outliers from the relationship, but both of them have monitoring light curves that raise doubt regarding the accuracy of their reported time lags. The scatter around the relationship is found to be 0.19 {+-} 0.02 dex, but would be decreased to 0.13 dex by the removal of these two suspect measurements. A large fraction of the remaining scatter in the relationship is likely due to the inaccurate distances to the AGN host galaxies. Our results help support the possibility that the R{sub BLR}-L relationship could potentially be used to turn the BLRs of AGNs into standardizable candles. This would allow the cosmological expansion of the universe to be probed by a separate population of objects, and over a larger range of redshifts.

  10. The ATLAS Muon Trigger at high instantaneous luminosities

    International Nuclear Information System (INIS)

    The ATLAS experiment at CERN's Large Hadron Collider (LHC) has taken data with colliding beams at instantaneous luminosities of 3.65 1033 cm?2 s?1. The LHC delivered an integrated luminosity of about 5fb?1 in the run period 2011, which required dedicated strategies to guard the highest physics output while reducing effectively the event rate. The Muon High Level Trigger has successfully adapted to the changing environment of the low luminosity running of LHC in 2010 to the luminosities encountered in 2011. The selection strategy has been optimized for the various physics analyses involving muons in the final state. This note reports about the performance of the muon trigger.

  11. Identifying the Low-Luminosity Population of Embedded Protostars in the c2d Observations of Clouds and Cores

    Science.gov (United States)

    Dunham, Michael M.; Crapsi, Antonio; Evans, Neal J., II; Bourke, Tyler L.; Huard, Tracy L.; Myers, Philip C.; Kauffmann, Jens

    2008-11-01

    We present the results of a search for all embedded protostars with internal luminosities = 4 10?3(d/140 pc)2 L?, a factor of 25 better than the sensitivity of the Infrared Astronomical Satellite (IRAS) to such objects. We present a set of selection criteria used to identify candidates from the Spitzer data and examine complementary data to decide whether each candidate is truly an embedded protostar. We find a tight correlation between the 70 ?m flux and internal luminosity of a protostar, an empirical result based on both observations and detailed two-dimensional radiative transfer models of protostars. We identify 50 embedded protostars with Lint <= 1.0 L? 15 have Lint <= 0.1 L?. The intrinsic distribution of source luminosities increases to lower luminosities. While we find sources down to the above sensitivity limit, indicating that the distribution may extend to luminosities lower than probed by these observations, we are able to rule out a continued rise in the distribution below Lint = 0.1 L?. Between 75% and 85% of cores classified as starless prior to being observed by Spitzer remain starless to our luminosity sensitivity; the remaining 15%-25% harbor low-luminosity, embedded protostars. We compile complete spectral energy distributions for all 50 objects and calculate standard evolutionary signatures (Lbol, Tbol, and Lbol/Lsmm) and argue that these objects are inconsistent with the simplest picture of star formation, wherein mass accretes from the core onto the protostar at a constant rate.

  12. Flavour Physics with High-Luminosity Experiments

    CERN Document Server

    2016-01-01

    With the first dedicated B-factory experiments BaBar (USA) and BELLE (Japan) Flavour Physics has entered the phase of precision physics. LHCb (CERN) and the high luminosity extension of KEK-B together with the state of the art BELLE II detector will further push this precision frontier. Progress in this field always relied on close cooperation between experiment and theory, as extraction of fundamental parameters often is very indirect. To extract the full physics information from existing and future data, this cooperation must be further intensified. This MIAPP programme aims in particular to prepare for this task by joining experimentalists and theorists in the various relevant fields, with the goal to build the necessary tools in face of the challenge of new large data sets. The programme will begin with a focus on physics with non-leptonic final states, continued by semileptonic B meson decays and Tau decays, and on various aspects of CP symmetry violation closer to the end. In addition, in the final ...

  13. Intrinsic luminosities of the Jovian planets

    International Nuclear Information System (INIS)

    We review available data and theories on the size and nature of interior power sources in the Jovian planets. Broad band infrared measurements indicate that Jupiter and Saturn have interior heat fluxes about 150 and 50 times larger, respectively, than the terrestrial value. While Neptune has a modest heat flux (approx.5 times terrestrial), it is clearly detected by earth-based measurements. Only Uranus seems to lack a detectable interior heat flow. Various models, ranging from simple cooling to gravitational layering to radioactivity, are discussed. Current evidence seems to favor a cooling model in which the escape of heat is regulated by the atmosphere. This model seems capable of explaining phenomena such as the uniformity of effective temperature over Jupiter's surface and the different emission rates of Uranus and Neptune. In such a model the heat radiated from the atmosphere may derived from depletion of a thermal reservoir in the interior, or it may derive from separation of chemical elements during formation of a core. Calculations indicate that in the earlier stages of cooling, Jupiter and Saturn may have more homogeneous abundances of hydrogen and helium and radiate energy derived from simple cooling. At a subsequent phase (which may be later than the present time), hydrogen and helium will separate and supply grativational energy. Either model is consistent with a hot, high-luminosity origin for the Jovian Planets

  14. The Luminosities of the Coldest Brown Dwarfs

    CERN Document Server

    Tinney, C G; Kirkpatrick, J Davy; Cushing, Mike; Morley, Caroline V; Wright, Edward L

    2014-01-01

    In recent years brown dwarfs have been extended to a new Y-dwarf class with effective temperatures colder than 500K and masses in the range 5-30 Jupiter masses. They fill a crucial gap in observable atmospheric properties between the much colder gas-giant planets of our own Solar System (at around 130K) and both hotter T-type brown dwarfs and the hotter planets that can be imaged orbiting young nearby stars (both with effective temperatures of in the range 1500-1000K). Distance measurements for these objects deliver absolute magnitudes that make critical tests of our understanding of very cool atmospheres. Here we report new distances for nine Y dwarfs and seven very-late T dwarfs. These reveal that Y dwarfs do indeed represent a continuation of the T dwarf sequence to both fainter luminosities and cooler temperatures. They also show that the coolest objects display a large range in absolute magnitude for a given photometric colour. The latest atmospheric models show good agreement with the majority of these ...

  15. Luminosity distributions of Type Ia Supernovae

    CERN Document Server

    Ashall, Chris; Sasdelli, Michele; Prentice, Simon

    2016-01-01

    We have assembled a dataset of 165 low redshift, $z<$0.06, publicly available type Ia supernovae (SNe Ia). We produce maximum light magnitude ($M_{B}$ and $M_{V}$) distributions of SNe Ia to explore the diversity of parameter space that they can fill. Before correction for host galaxy extinction we find that the mean $M_{B}$ and $M_{V}$ of SNe Ia are $-18.58\\pm0.07$mag and $-18.72\\pm0.05$mag respectively. Host galaxy extinction is corrected using a new method based on the SN spectrum. After correction, the mean values of $M_{B}$ and $M_{V}$ of SNe Ia are $-19.10\\pm0.06$ and $-19.10\\pm0.05$mag respectively. After correction for host galaxy extinction, `normal' SNeIa ($\\Delta m_{15}(B)<1.6$mag) fill a larger parameter space in the Width-Luminosity Relation (WLR) than previously suggested, and there is evidence for luminous SNe Ia with large $\\Delta m_{15}(B)$. We find a bimodal distribution in $\\Delta m_{15}(B)$, with a pronounced lack of transitional events at $\\Delta m_{15}(B)$=1.6 mag. We confirm that ...

  16. ATLAS gets its own luminosity detector

    CERN Multimedia

    CERN Bulletin

    2011-01-01

    During the winter shutdown, the ATLAS collaboration has completed the installation of ALFA, the detector system that aims at the LHC absolute luminosity at Point 1 analysing the elastic scattering of protons at small angles.   Upper and lower ALFA Roman Pots as installed in sector 8-1 of the LHC tunnel, 240 metres from the ATLAS Interaction Point. The detectors of the ALFA system are installed at ± 240 meters from the interaction point 1, on either side of the ATLAS detector. The whole system consists of four stations, two on each side of the interaction point. Each station is equipped with two Roman Pots; each pot – that is separated from the vacuum of the accelerator by a thin window but is connected with bellows to the beam-pipe – can be moved very close to the beam. “The Roman Pot technique has been used successfully in the past for the measurement of elastic scattering very close to the circulating beam,” says Patrick Fassn...

  17. CONSTRAINING PHYSICAL PROPERTIES OF TYPE IIn SUPERNOVAE THROUGH RISE TIMES AND PEAK LUMINOSITIES

    International Nuclear Information System (INIS)

    We investigate the diversity in the wind density, supernova ejecta energy, and ejecta mass in Type IIn supernovae based on their rise times and peak luminosities. We show that the wind density and supernova ejecta properties can be estimated independently if both the rise time and peak luminosity are observed. The peak luminosity is mostly determined by the supernova properties and the rise time can be used to estimate the wind density. We find that the ejecta energies of Type IIn supernovae need to vary by factors of 0.2-5 from the average if their ejecta masses are similar. The diversity in the observed rise times indicates that their wind densities vary by factors of 0.2-2 from the average. We show that Type IIn superluminous supernovae should have not only large wind density but also large ejecta energy and/or small ejecta mass to explain their large luminosities and the rise times at the same time. We also note that shock breakout does not necessarily occur in the wind even if it is optically thick, except for the case of superluminous supernovae, and we analyze the observational data both with and without assuming that the shock breakout occurs in the dense wind of Type IIn supernovae

  18. Hadron-hadron physics at high energy and luminosity

    Energy Technology Data Exchange (ETDEWEB)

    Hinchliffe, I.

    1989-11-08

    I review some recent theoretical issues relevant to the physics of hadron-hadron collisions. I discuss processes where either energy or luminosity is the most important feature and emphasize the need for experiments at luminosities of 10{sup 33}cm{sup -2}sec{sup 1} if the full range of physics options is to be thoroughly explored. 22 refs., 10 figs.

  19. Luminosities for collisions of intermediate bosons and other partons

    International Nuclear Information System (INIS)

    Parton-parton luminosities (l/s) dpounds/d tau are presented for WW, WZ, ZZ, γW, γZ, γγ, Wg, Wq, Zg, and Zq collisions. A comparison between the exact calculation and the calculation using our luminosities for Higgs boson production from WW fusion is also presented

  20. Overview of a high luminosity μ+μ- collider

    International Nuclear Information System (INIS)

    Muon Colliders have unique technical and physics advantages and disadvantages when compared with both hadron and electron machines. They should be regarded as complementary. Parameters are given of a 4 TeV high luminosity μ+μ- collider, and of a 0.5 TeV lower luminosity demonstration machine. The authors discuss the various systems in such muon colliders

  1. Bolometric Luminosity Correction of H2O Maser AGNs

    Indian Academy of Sciences (India)

    Q. Guo; J. S. Zhang; J. Wang

    2014-09-01

    For the H2O maser host AGN sample, we derived their bolometric luminosity corrections, based on their X-ray data and [O III] emission line luminosities. Our results for maser AGNs is comparable to that of non-maser AGNs.

  2. Luminosity lifetime at an asymmetric e+e- collider

    International Nuclear Information System (INIS)

    The dependence of the luminosity on time is discussed for an asymmetric e+e- storage ring collider, with emphasis on single-particle scattering mechanisms for beam loss. The 'optimal' filling strategy and average luminosity obtainable are also reviewed. (orig.)

  3. ATLAS Future Plans: Upgrade and the Physics with High Luminosity

    CERN Document Server

    Rajagopalan, Srini; The ATLAS collaboration

    2012-01-01

    ATLAS is planning a series of detector upgrades to cope with increasing instantaneous luminosity and multiple interactions per crossing to ensure that acceptance to new physics and precision measurements are preserved. During the next several years, LHC is expected to collide protons on protons at a center of mass energy up to 14 TeV with luminosities reaching 1 to 2 x 1034 cm^-2 s^-1, accumulating ~100 fb^-1 per year following a Phase 1 Upgrade (2018). The detector upgrades focus on precision tracking and improved trigger capabilities to sustain higher rates. Subsequently, the LHC plans calls for a five-fold increase in instantaneous luminosity, thereby increasing the delivered luminosity to ~3000 fb^-1 by 2030. The increased luminosity will significantly increase the physics reach of ATLAS building on the recent discovery of the Higgs-like boson. The planned detector upgrades and the impact on the ATLAS physics program will be discussed.

  4. Assessing the contribution of Centaur impacts to ice giant luminosities

    CERN Document Server

    Dodson-Robinson, Sarah E

    2015-01-01

    Voyager 2 observations revealed that the internal luminosity of Neptune is an order of magnitude higher than that of Uranus. If the two planets have similar interior structures and cooling histories, the luminosity of Neptune can only be explained by invoking some energy source beyond gravitational contraction. This paper investigates whether Centaur impacts could provide the energy necessary to produce the luminosity of Neptune. The major findings are (1) that impacts on both Uranus and Neptune are too infrequent to provide luminosities of order the observed value for Neptune, even for optimistic impact-rate estimates, and (2) that Uranus and Neptune rarely have significantly different impact-generated luminosities at any given time. Uranus and Neptune most likely have structural differences that force them to cool and contract at different rates.

  5. Assessing the contribution of centaur impacts to ice giant luminosities

    Science.gov (United States)

    Dodson-Robinson, Sarah E.

    2016-01-01

    Voyager 2 observations revealed that Neptune's internal luminosity is an order of magnitude higher than that of Uranus. If the two planets have similar interior structures and cooling histories, Neptune's luminosity can only be explained by invoking some energy source beyond gravitational contraction. This paper investigates whether centaur impacts could provide the energy necessary to produce Neptune's luminosity. The major findings are (1) that impacts on both Uranus and Neptune are too infrequent to provide luminosities of order Neptune's observed value, even for optimistic impact-rate estimates and (2) that Uranus and Neptune rarely have significantly different impact-generated luminosities at any given time. Uranus and Neptune most likely have structural differences that force them to cool and contract at different rates.

  6. Evolution of the cluster X-ray luminosity function

    DEFF Research Database (Denmark)

    Mullis, C.R.; Vikhlinin, A.; Henry, J.P.; Forman, W.; Gioia, I.M.; Hornstrup, Allan; Jones, C.; McNamara, B.R.; Quintana, H.

    2004-01-01

    We report measurements of the cluster X-ray luminosity function out to z = 0.8 based on the final sample of 201 galaxy systems from the 160 Square Degree ROSAT Cluster Survey. There is little evidence for any measurable change in cluster abundance out to z similar to 0.6 at luminosities of less...... and a maximum likelihood analysis of the observed luminosity-redshift distribution fit with a model luminosity function. The negative evolution signal is more than 3 sigma regardless of the adopted local luminosity function or cosmological framework. Our results and those from several other surveys...... independently confirm the presence of evolution. Whereas the bulk of the cluster population does not evolve, the most luminous and presumably most massive structures evolve appreciably between z = 0.8 and the present. Interpreted in the context of hierarchical structure formation, we are probing sufficiently...

  7. Possible relationship between metal abundance and luminosity for disk galaxies

    International Nuclear Information System (INIS)

    Near-infrared colors have been measured for a sample of 31 late-type galaxies in the Pegasus I and Pisces clusters; system luminosities in the sample cover the range -19< M/sub H/<-23.5. The color index (J-K) correlates strongly with the absolute H magnitude; lower-luminosity systems have bluer colors. These observations are consistent with the assumption that the mean metal abundance of the old disk population decreases systematically with luminosity. The systematic variation of (B-H) with absolute H magnitude reported recently by Tully et al. derives in part from this proposed systematic change of metallicity with luminosity. However, one must still posit a relative increase in the number of newly formed stars and/or a systematic smaller age for lower-luminosity disks in order to fully explain the observed (B-H), H relation

  8. The luminosities of the coldest brown dwarfs

    Energy Technology Data Exchange (ETDEWEB)

    Tinney, C. G. [School of Physics, UNSW Australia, NSW 2052 (Australia); Faherty, Jacqueline K. [Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington DC 20005 (United States); Kirkpatrick, J. Davy [Infrared Processing and Analysis Center, MS100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Cushing, Mike [Department of Physics and Astronomy, The University of Toledo, OH 43606 (United States); Morley, Caroline V. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Wright, Edward L., E-mail: c.tinney@unsw.edu.au [Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095-1547 (United States)

    2014-11-20

    In recent years, brown dwarfs have been extended to a new Y-dwarf class with effective temperatures colder than 500 K and masses in the range of 5-30 Jupiter masses. They fill a crucial gap in observable atmospheric properties between the much colder gas-giant planets of our own solar system (at around 130 K) and both hotter T-type brown dwarfs and the hotter planets that can be imaged orbiting young nearby stars (both with effective temperatures in the range of 1500-1000 K). Distance measurements for these objects deliver absolute magnitudes that make critical tests of our understanding of very cool atmospheres. Here we report new distances for nine Y dwarfs and seven very late T dwarfs. These reveal that Y dwarfs do indeed represent a continuation of the T-dwarf sequence to both fainter luminosities and cooler temperatures. They also show that the coolest objects display a large range in absolute magnitude for a given photometric color. The latest atmospheric models show good agreement with the majority of these Y-dwarf absolute magnitudes. This is also the case for WISE0855-0714, the coldest and closest brown dwarf to the Sun, which shows evidence for water ice clouds. However, there are also some outstanding exceptions, which suggest either binarity or the presence of condensate clouds. The former is readily testable with current adaptive optics facilities. The latter would mean that the range of cloudiness in Y dwarfs is substantial with most hosting almost no clouds—while others have dense clouds, making them prime targets for future variability observations to study cloud dynamics.

  9. The Luminosities of the Coldest Brown Dwarfs

    Science.gov (United States)

    Tinney, C. G.; Faherty, Jacqueline K.; Kirkpatrick, J. Davy; Cushing, Mike; Morley, Caroline V.; Wright, Edward L.

    2014-11-01

    In recent years, brown dwarfs have been extended to a new Y-dwarf class with effective temperatures colder than 500 K and masses in the range of 5-30 Jupiter masses. They fill a crucial gap in observable atmospheric properties between the much colder gas-giant planets of our own solar system (at around 130 K) and both hotter T-type brown dwarfs and the hotter planets that can be imaged orbiting young nearby stars (both with effective temperatures in the range of 1500-1000 K). Distance measurements for these objects deliver absolute magnitudes that make critical tests of our understanding of very cool atmospheres. Here we report new distances for nine Y dwarfs and seven very late T dwarfs. These reveal that Y dwarfs do indeed represent a continuation of the T-dwarf sequence to both fainter luminosities and cooler temperatures. They also show that the coolest objects display a large range in absolute magnitude for a given photometric color. The latest atmospheric models show good agreement with the majority of these Y-dwarf absolute magnitudes. This is also the case for WISE0855-0714, the coldest and closest brown dwarf to the Sun, which shows evidence for water ice clouds. However, there are also some outstanding exceptions, which suggest either binarity or the presence of condensate clouds. The former is readily testable with current adaptive optics facilities. The latter would mean that the range of cloudiness in Y dwarfs is substantial with most hosting almost no cloudswhile others have dense clouds, making them prime targets for future variability observations to study cloud dynamics. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

  10. Kinetic Luminosity and Composition of Active Galactic Nuclei Jets

    CERN Document Server

    Hirotani, K

    2004-01-01

    We present a new method how to discriminate the matter content of parsec-scale jets of active galactic nuclei. By constraining the kinetic luminosity of a jet from the observed core size at a single very long baseline interferometry frequency, we can infer the electron density of a radio-emitting component as a function of the composition. Comparing this density with that obtained from the theory of synchrotron self-absorption, we can determine the composition. We apply this procedure to the five components in the 3C~345 jet and find that they are likely pair-plasma dominated at 11 epochs out of the total 21 epochs, provided that the bulk Lorentz factor is less than 15 throughout the jet. We also investigate the composition of the 3C~279 jet and demonstrate that its two components are likely pair-plasma dominated at three epochs out of four epochs, provided that their Doppler factors are less than 10, which are consistent with observations. The conclusions do not depend on the lower cutoff energy of radiating...

  11. GALAXY CLUSTERING IN THE COMPLETED SDSS REDSHIFT SURVEY: THE DEPENDENCE ON COLOR AND LUMINOSITY

    International Nuclear Information System (INIS)

    We measure the luminosity and color dependence of galaxy clustering in the largest-ever galaxy redshift survey, the main galaxy sample of the Sloan Digital Sky Survey Seventh Data Release. We focus on the projected correlation function wp (rp ) of volume-limited samples, extracted from the parent sample of ∼700,000 galaxies over 8000 deg2, extending up to redshift of 0.25. We interpret our measurements using halo occupation distribution (HOD) modeling assuming a ΛCDM cosmology (inflationary cold dark matter with a cosmological constant). The amplitude of wp (rp ) grows slowly with luminosity for L * and increases sharply at higher luminosities, with a large-scale bias factor b(> L) x (σ8/0.8) = 1.06 + 0.21(L/L*)1.12, where L is the sample luminosity threshold. At fixed luminosity, redder galaxies exhibit a higher amplitude and steeper correlation function, a steady trend that runs through the 'blue cloud' and 'green valley' and continues across the 'red sequence'. The cross-correlation of red and blue galaxies is close to the geometric mean of their autocorrelations, dropping slightly below at rp -1 Mpc. The luminosity trends for the red and blue galaxy populations separately are strikingly different. Blue galaxies show a slow but steady increase of clustering strength with luminosity, with nearly constant shape of wp (rp ). The large-scale clustering of red galaxies shows little luminosity dependence until a sharp increase at L > 4 L*, but the lowest luminosity red galaxies (0.04-0.25 L*) show very strong clustering on small scales (rp -1 Mpc). Most of the observed trends can be naturally understood within the ΛCDM+HOD framework. The growth of wp (rp ) for higher luminosity galaxies reflects an overall shift in the mass scale of their host dark matter halos, in particular an increase in the minimum host halo mass Mmin. The mass at which a halo has, on average, one satellite galaxy brighter than L is M1 ∼ 17 Mmin(L) over most of the luminosity range, with a smaller ratio above L*. The growth and steepening of wp (rp ) for redder galaxies reflects the increasing fraction of galaxies that are satellite systems in high-mass halos instead of central systems in low-mass halos, a trend that is especially marked at low luminosities. Our extensive measurements, provided in tabular form, will allow detailed tests of theoretical models of galaxy formation, a firm grounding of semiempirical models of the galaxy population, and new constraints on cosmological parameters from combining real-space galaxy clustering with mass-sensitive statistics such as redshift-space distortions, cluster mass-to-light ratios, and galaxy-galaxy lensing.

  12. Near-Infrared Properties of Moderate-Redshift Galaxy Clusters: Luminosity Functions and Density Profiles

    Energy Technology Data Exchange (ETDEWEB)

    Muzzin, Adam; Yee, H.K.C.; /Toronto U., Astron. Dept.; Hall, Patrick B.; /York U., Canada; Ellingson, E.; /Colorado U., CASA; Lin, Huan; /Fermilab

    2006-12-01

    We present K-band imaging for 15 of the Canadian Network for Observational Cosmology (CNOC1) clusters. The extensive spectroscopic dataset available for these clusters allows us to determine the cluster K-band luminosity function and density profile without the need for statistical background subtraction. The luminosity density and number density profiles can be described by NFW models with concentration parameters of c{sub l} = 4.28 {+-} 0.70 and c{sub g} = 4.13 {+-} 0.57 respectively. Comparing these to the dynamical mass analysis of the same clusters shows that the galaxy luminosity and number density profiles are similar to the dark matter profile, and are not less concentrated like in local clusters. The luminosity functions show that the evolution of K. over the redshift range 0.2 < z < 0.5 is consistent with a scenario where the majority of stars in cluster galaxies form at high-redshift (z{sub f} > 1.5) and evolve passively thereafter. The best-fit for the faint-end slope of the luminosity function is {alpha} = -0.84 {+-} 0.08, which indicates that it does not evolve between z = 0 and z = 0.3. Using Principal Component Analysis of the spectra we classify cluster galaxies as either star-forming/recently-star-forming (EM+BAL) or non-star forming (ELL) and compute their respective luminosity functions. The faint-end slope of the ELL luminosity function is much shallower than for the EM+BAL galaxies at z = 0.3, and suggests the number of faint ELL galaxies in clusters decreases by a factor of {approx} 3 from z = 0 to z = 0.3. The redshift evolution of K* for both EM+BAL and ELL types is consistent with a passively evolving stellar population formed at high-redshift. Passive evolution in both classes, as well as the total cluster luminosity function, demonstrates that the bulk of the stellar population in all bright cluster galaxies is formed at high-redshift and subsequent transformations in morphology/color/spectral-type have little effect on the total stellar mass.

  13. Luminosity measurement and beam condition monitoring at CMS

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, Jessica Lynn [DESY, Zeuthen (Germany)

    2015-07-01

    The BRIL system of CMS consists of instrumentation to measure the luminosity online and offline, and to monitor the LHC beam conditions inside CMS. An accurate luminosity measurement is essential to the CMS physics program, and measurement of the beam background is necessary to ensure safe operation of CMS. In expectation of higher luminosity and denser proton bunch spacing during LHC Run II, many of the BRIL subsystems are being upgraded and others are being added to complement the existing measurements. The beam condition monitor (BCM) consists of several sets of diamond sensors used to measure online luminosity and beam background with a single-bunch-crossing resolution. The BCM also detects when beam conditions become unfavorable for CMS running and may trigger a beam abort to protect the detector. The beam halo monitor (BHM) uses quartz bars to measure the background of the incoming beams at larger radii. The pixel luminosity telescope (PLT) consists of telescopes of silicon sensors designed to provide a CMS online and offline luminosity measurement. In addition, the forward hadronic calorimeter (HF) will deliver an independent luminosity measurement, making the whole system robust and allowing for cross-checks of the systematics. Data from each of the subsystems will be collected and combined in the BRIL DAQ framework, which will publish it to CMS and LHC. The current status of installation and commissioning results for the BRIL subsystems are given.

  14. GALACTIC ULTRACOMPACT X-RAY BINARIES: EMPIRICAL LUMINOSITIES

    International Nuclear Information System (INIS)

    Ultracompact X-ray binaries (UCXBs) are thought to have relatively simple binary evolution post-contact, leading to clear predictions of their luminosity function. We test these predictions by studying the long-term behavior of known UCXBs in our Galaxy, principally using data from the MAXI All-Sky Survey and the Galactic bulge scans with RXTE's Proportional Counter Array instrument. Strong luminosity variations are common (and well documented) among persistent UCXBs, which requires an explanation other than the disk instability mechanism. We measure the luminosity function of known UCXBs in the Milky Way, which extends to lower luminosities than some proposed theoretical luminosity functions of UCXBs. The difference between field and globular cluster (GC) X-ray luminosity functions in other galaxies cannot be explained by an increased fraction of UCXBs in GCs. Instead, our measured luminosity function suggests that UCXBs only make up a small fraction of the X-ray binaries above a few 1036 erg s1 in both old field populations and GCs.

  15. GRB 120422A: A LOW-LUMINOSITY GAMMA-RAY BURST DRIVEN BY A CENTRAL ENGINE

    International Nuclear Information System (INIS)

    GRB 120422A is a low-luminosity gamma-ray burst (GRB) associated with a bright supernova, which distinguishes itself by its relatively short T90 (∼5 s) and an energetic and steep-decaying X-ray tail. We analyze the Swift Burst Alert Telescope and X-ray Telescope data and discuss the physical implications. We show that the steep decline early in the X-ray light curve can be interpreted as the curvature tail of a late emission episode around 58-86 s, with a curved instantaneous spectrum at the end of the emission episode. Together with the main activity in the first ∼20 s and the weak emission from 40 s to 60 s, the prompt emission is variable, which points to a central engine origin in contrast to a shock-breakout origin, which is used to interpret some other nearby low-luminosity supernova GRBs. Both the curvature effect model and interpreting the early shallow decay as the coasting external forward shock emission in a wind medium provide a constraint on the bulk Lorentz factor Γ to be around several. Comparing the properties of GRB 120422A and other supernova GRBs, we find that the main criterion to distinguish engine-driven GRBs from shock-breakout GRBs is the time-averaged γ-ray luminosity. Engine-driven GRBs likely have a luminosity above ∼1048 erg s–1.

  16. GRB 120422A: a Low-Luminosity Gamma-Ray Burst Driven by a Central Engine

    Science.gov (United States)

    Zhang, Bin-Bin; Fan, Yi-Zhong; Shen, Rong-Feng; Xu, Dong; Zhang, Fu-Wen; Wei, Da-Ming; Burrows, David N.; Zhang, Bing; Gehrels, Neil

    2012-01-01

    GRB 120422A is a low-luminosity gamma-ray burst (GRB) associated with a bright supernova, which distinguishesitself by its relatively short T(sub 90) (approximately 5 s) and an energetic and steep-decaying X-ray tail. We analyze the Swift BurstAlert Telescope and X-ray Telescope data and discuss the physical implications. We show that the steep declineearly in the X-ray light curve can be interpreted as the curvature tail of a late emission episode around 58-86 s,with a curved instantaneous spectrum at the end of the emission episode. Together with the main activity in thefirst 20 s and the weak emission from 40 s to 60 s, the prompt emission is variable, which points to a centralengine origin in contrast to a shock-breakout origin, which is used to interpret some other nearby low-luminosity supernova GRBs. Both the curvature effect model and interpreting the early shallow decay as the coasting externalforward shock emission in a wind medium provide a constraint on the bulk Lorentz factor to be around several.Comparing the properties ofGRB 120422A and other supernova GRBs,we find that themain criterion to distinguish engine-driven GRBs from shock-breakout GRBs is the time-averaged -ray luminosity. Engine-driven GRBs likelyhave a luminosity above approximately 10(sup 48) erg s(sup -1).

  17. TRUNCATION OF THE INNER ACCRETION DISK AROUND A BLACK HOLE AT LOW LUMINOSITY

    International Nuclear Information System (INIS)

    Most black hole binaries show large changes in X-ray luminosity caused primarily by variations in mass accretion rate. An important question for understanding black hole accretion and jet production is whether the inner edge of the accretion disk recedes at low accretion rate. Measurements of the location of the inner edge (R in) can be made using iron emission lines that arise due to fluorescence of iron in the disk, and these indicate that R in is very close to the black hole at high and moderate luminosities (?>1% of the Eddington luminosity, L Edd). Here, we report on X-ray observations of the black hole GX 339 - 4 in the hard state by Suzaku and the Rossi X-ray Timing Explorer that extend iron line studies to 0.14% L Edd and show that R in increases by a factor of >27 over the value found when GX 339 - 4 was bright. The exact value of R in depends on the inclination of the inner disk (i), and we derive 90% confidence limits of R in > 35Rg at i = 00 and R in > 175Rg at i = 300. This provides direct evidence that the inner portion of the disk is not present at low luminosity, allowing for the possibility that the inner disk is replaced by advection- or magnetically dominated accretion flows.

  18. Tile Calorimeter Upgrade Program for the Luminosity Increasing at the LHC

    CERN Document Server

    Cerqueira, Augusto Santiago; The ATLAS collaboration

    2015-01-01

    The Tile Calorimeter (TileCal) is the central hadronic calorimeter of the ATLAS experiment at the Large Hadron Collider (LHC). TileCal is a sampling calorimeter with approximately 10,000 channels and is operating successfully (data quality efficiency above 99%) in ATLAS, since the start of the LHC collisions. The LHC is scheduled to undergo a major upgrade, in 2022, for the High Luminosity LHC (HL-LHC), where the luminosity will be increased by a factor of 10 above the original design value. The ATLAS upgrade program for high luminosity is split into three phases: Phase 0 occurred during 2013-2014 (Long Shutdown 1), and prepared the LHC for run 2; Phase 1, foreseen for 2019 (Long Shutdown 2), will prepare the LHC for run 3, whereafter the peak luminosity reaches 2-3 x 10^{34} cm^{2}s^{-1}; finally, Phase 2, which is foreseen for 2023 (Long Shutdown 3), will prepare the collider for the HL-LHC operation (5-7 x 10^{34} cm^{2}s^{-1}). The TileCal main activities for Phase 0 were the installation of the new low v...

  19. The X-ray luminosity function of AGN at z~3

    CERN Document Server

    Aird, James; Georgakakis, Antonis; Laird, Elise S; Steidel, Charles C; Sharon, Chelsea

    2008-01-01

    We combine Lyman-break colour selection with ultradeep (> 200 ks) Chandra X-ray imaging over a survey area of ~0.35 deg^2 to select high redshift AGN. Applying careful corrections for both the optical and X-ray selection functions, the data allow us to make the most accurate determination to date of the faint end of the X-ray luminosity function (XLF) at z~3. Our methodology recovers a number density of X-ray sources at this redshift which is at least as high as previous surveys, demonstrating that it is an effective way of selecting high z AGN. Comparing to results at z=1, we find no evidence that the faint slope of the XLF flattens at high z, but we do find significant (factor ~3.6) negative evolution of the space density of low luminosity AGN. Combining with bright end data from very wide surveys we also see marginal evidence for continued positive evolution of the characteristic break luminosity L*. Our data therefore support models of luminosity-dependent density evolution between z=1 and z=3. A sharp up...

  20. Tile Calorimeter Upgrade Program for the Luminosity Increasing at the LHC

    CERN Document Server

    Cerqueira, Augusto Santiago; The ATLAS collaboration

    2015-01-01

    The Tile Calorimeter (TileCal) is the central hadronic calorimeter of the ATLAS experiment at the Large Hadron Collider (LHC). TileCal is a sampling calorimeter with approximately 10,000 channels and is operating successfully (data quality efficiency above 99%) in ATLAS, since the start of the LHC collisions. The LHC is scheduled to undergo a major upgrade, in 2022, for the High Luminosity LHC (HL-LHC), where the luminosity will be increased by a factor of 10 above the original design value. The ATLAS upgrade program for high luminosity is split into three phases: Phase 0 occurred during 2013-2014 (Long Shutdown 1), and prepared the LHC for run 2; Phase 1, foreseen for 2019 (Long Shutdown 2), will prepare the LHC for run 3, whereafter the peak luminosity reaches 2-3 x 10^{34} cm^{2}s^{-1}; finally, Phase 2, which is foreseen for 2024 (Long Shutdown 3), will prepare the collider for the HL-LHC operation (5-7 x 10^{34} cm^{2}s^{-1}). The TileCal main activities for Phase 0 were the installation of the new low v...

  1. The Luminosity Function of Fermi-detected Flat-Spectrum Radio Quasars

    Energy Technology Data Exchange (ETDEWEB)

    Ajello, M.; Shaw, M.S.; Romani, R.W.; Dermer, C.D.; Costamante, L.; King, O.G.; Max-Moerbeck, W.; Readhead, A.; Reimer, A.; Richards, J.L.; Stevenson, M.

    2012-04-16

    Fermi has provided the largest sample of {gamma}-ray selected blazars to date. In this work we use a complete sample of FSRQs detected during the first year of operation to determine the luminosity function (LF) and its evolution with cosmic time. The number density of FSRQs grows dramatically up to redshift {approx}0.5-2.0 and declines thereafter. The redshift of the peak in the density is luminosity dependent, with more luminous sources peaking at earlier times; thus the LF of {gamma}-ray FSRQs follows a luminosity-dependent density evolution similarly to that of radio-quiet AGN. Also using data from the Swift Burst Alert Telescope we derive the average spectral energy distribution of FSRQs in the 10 keV-100GeV band and show that there is no correlation of the peak {gamma}-ray luminosity with {gamma}-ray peak frequency. The coupling of the SED and LF allows us to predict that the contribution of FSRQs to the Fermi isotropic {gamma}-ray background is 9.3{sub -1.0}{sup +1.6}% ({+-}3% systematic uncertainty) in the 0.1-100GeV band. Finally we determine the LF of unbeamed FSRQs, finding that FSRQs have an average Lorentz factor of {gamma} = 11.7{sub -2.2}{sup +3.3}, that most are seen within 5{sup o} of the jet axis, and that they represent only {approx}0.1% of the parent population.

  2. Does the obscured AGN fraction really depend on luminosity?

    Science.gov (United States)

    Sazonov, S.; Churazov, E.; Krivonos, R.

    2015-12-01

    We use a sample of 151 local non-blazar active galactic nuclei (AGN) selected from the INTEGRAL all-sky hard X-ray survey to investigate if the observed declining trend of the fraction of obscured (i.e. showing X-ray absorption) AGN with increasing luminosity is mostly an intrinsic or selection effect. Using a torus-obscuration model, we demonstrate that in addition to negative bias, due to absorption in the torus, in finding obscured AGN in hard X-ray flux-limited surveys, there is also positive bias in finding unobscured AGN, due to Compton reflection in the torus. These biases can be even stronger taking into account plausible intrinsic collimation of hard X-ray emission along the axis of the obscuring torus. Given the AGN luminosity function, which steepens at high luminosities, these observational biases lead to a decreasing observed fraction of obscured AGN with increasing luminosity even if this fraction has no intrinsic luminosity dependence. We find that if the central hard X-ray source in AGN is isotropic, the intrinsic (i.e. corrected for biases) obscured AGN fraction still shows a declining trend with luminosity, although the intrinsic obscured fraction is significantly larger than the observed one: the actual fraction is larger than ˜85 per cent at L ≲ 1042.5 erg s-1 (17-60 keV), and decreases to ≲60 per cent at L ≳ 1044 erg s-1. In terms of the half-opening angle θ of an obscuring torus, this implies that θ ≲ 30° in lower luminosity AGN, and θ ≳ 45° in higher luminosity ones. If, however, the emission from the central supermassive black hole is collimated as dL/dΩ ∝ cos α, the intrinsic dependence of the obscured AGN fraction is consistent with a luminosity-independent torus half-opening angle θ ˜ 30°.

  3. Seeking the epoch of maximum luminosity for dusty quasars

    International Nuclear Information System (INIS)

    Infrared luminosities νLν(7.8 μm) arising from dust reradiation are determined for Sloan Digital Sky Survey (SDSS) quasars with 1.4 luminosity does not show a maximum at any redshift z < 5, reaching a plateau for z ≳ 3 with maximum luminosity νLν(7.8 μm) ≳ 1047 erg s–1; luminosity functions show one quasar Gpc–3 having νLν(7.8 μm) > 1046.6 erg s–1 for all 2 luminosity has not yet been identified at any redshift below 5. The most ultraviolet luminous quasars, defined by rest frame νLν(0.25 μm), have the largest values of the ratio νLν(0.25 μm)/νLν(7.8 μm) with a maximum ratio at z = 2.9. From these results, we conclude that the quasars most luminous in the ultraviolet have the smallest dust content and appear luminous primarily because of lessened extinction. Observed ultraviolet/infrared luminosity ratios are used to define 'obscured' quasars as those having >5 mag of ultraviolet extinction. We present a new summary of obscured quasars discovered with the Spitzer Infrared Spectrograph and determine the infrared luminosity function of these obscured quasars at z ∼ 2.1. This is compared with infrared luminosity functions of optically discovered, unobscured quasars in the SDSS and in the AGN and Galaxy Evolution Survey. The comparison indicates comparable numbers of obscured and unobscured quasars at z ∼ 2.1 with a possible excess of obscured quasars at fainter luminosities.

  4. Towards a new LHC Interaction Region design for a luminosity upgrade

    CERN Document Server

    Strait, J; Limon, P; Mokhov, N V; Sen, T; Zlobin, A V; Brüning, Oliver Sim; Ostojic, R; Rossi, L; Ruggiero, F; Taylor, T; ten Kate, H; Devred, A; Gupta, R; Harrison, M; Peggs, S; Pilat, F; Caspi, S; Gourlay, S; Sabbi, G

    2003-01-01

    After the LHC operates for several years at nominal parameters, it will be necessary to upgrade it for higher luminosity. Replacing the low-beta insertions with a higher performance design based on advanced superconducting magnets is one of the most straightforward steps in this direction. Preliminary studies show that, with magnet technology that is expected to be developed by early in the next decade, a factor of 2 to 5 reduction in beta* could be achieved with new insertions, as part of an upgrade aimed at a factor of 10 luminosity increase. In this paper we survey several possible second generation LHC interaction regions designs, which address the expected limitations on LHC performance imposed by the baseline insertions.

  5. Perspectives for Top quark physics at High-Luminosity LHC

    CERN Document Server

    Selvaggi, Michele

    2015-01-01

    The High-Luminosity LHC is expected to provide $3 ab^{-1}$ of integrated luminosity. As a result billions of events containing top quarks will be detected at the CMS and ATLAS experiments, allowing for precise measurements of the top quark properties. The experimental challenges that will be faced in a high luminosity environment, with a special focus on top quark related observables are examined. We discuss prospects for measuring top quark anomalous couplings at the HL-LHC. Projections for detecting flavor changing neutral currents involving top quarks are also reviewed.

  6. The UVX quasar optical luminosity function and its evolution

    OpenAIRE

    Goldschmidt, Pippa; Miller, Lance,

    1997-01-01

    The recently-finished Edinburgh UVX quasar survey at B < 18 is used together with other complete samples to estimate the shape and evolution of the optical luminosity function in the redshift range 0.3 < z < 2.2. There is a significantly higher space density of quasars at high luminosity and low redshift than previously found in the PG sample of Schmidt & Green (1983), with the result that the shape of the luminosity function at low redshifts (z < 1) is seen to be consistent with a single pow...

  7. Rad-hard Luminosity Monitoring for the LHC

    International Nuclear Information System (INIS)

    Luminosity measurements at the high luminosity points of the LHC are very challenging due to the extremely high radiation levels in the order of 180 MGy/yr. They have designed an ionization chamber that uses a flowing inorganic gas mixture and a combination of metals and ceramics. With such a choice, an additional challenge is achieving the necessary speed to be able to resolve bunch-by-bunch luminosity data. They present the design, analysis and experimental results of the early demonstration tests of this device

  8. The GRB Variability/Peak Luminosity Correlation: new results

    CERN Document Server

    Guidorzi, C; Montanari, E; Rossi, F; Amati, L; Gomboc, A; Hurley, K; Mundell, C G

    2005-01-01

    We report test results of the correlation between time variability and peak luminosity of Gamma-Ray Bursts (GRBs), using a larger sample (32) of GRBs with known redshift than that available to Reichart et al. (2001), and using as variability measure that introduced by these authors. The results are puzzling. Assuming an isotropic-equivalent peak luminosity, as done by Reichart et al. (2001), a correlation is still found, but it is less relevant, and inconsistent with a power law as previously reported. Assuming as peak luminosity that corrected for GRB beaming for a subset of 16 GRBs with known beaming angle, the correlation becomes little less significant.

  9. Luminosities and Space Densities of Gamma-Ray Bursts

    OpenAIRE

    Schmidt, Maarten

    1999-01-01

    We use a homogeneous sample of gamma-ray bursts (GRB) extracted from 5.9 years of BATSE DISCLA data (astro-ph/9908190) and a variety of broken power-law luminosity functions to derive GRB luminosities and space densities. Luminosity functions that are narrow or exhibit no density evolution produce expected redshift distributions that are incompatible with the observation of a GRB redshift of 3.4. For q_o=0.1 and density evolution rising to 10 at z=1, we find for a variety of slopes of the lum...

  10. Cryogenic test of double quarter wave crab cavity for the LHC High luminosity upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, B. [Brookhaven National Lab. (BNL), Upton, NY (United States); Alberty, L. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Belomestnykh, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Ben-Zvi, I. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Calaga, R. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Cullen, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Capatina, O. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Hammons, L. [Brookhaven National Lab. (BNL), Upton, NY (United States); Li, Z. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Marques, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Skaritka, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Verdu-Andres, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wu, Q. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-05-03

    A Proof-of-Principle (PoP) Double Quarter Wave Crab Cavity (DQWCC) was designed and fabricated for the Large Hadron Collider (LHC) luminosity upgrade. A vertical cryogenic test has been done at Brookhaven National Lab (BNL). The cavity achieved 4.5 MV deflecting voltage with a quality factor above 3×109. We report the test results of this design.

  11. Upgrade of the ATLAS Calorimeters for Higher LHC Luminosities

    CERN Document Server

    ATLAS Tile Collaboration; The ATLAS collaboration

    2015-01-01

    The upgrade of the LHC will bring instantaneous and total luminosities which are a factor 5-7 beyond the original design of the ATLAS Liquid Argon (LAr) and Tile Calorimeters and their read-out systems. Due to radiation requirements and a new two-level hardware trigger concept the read-out electronics will be improved in two phases. In Phase-I, a dedicated read-out of the LAr Calorimeters will provide higher granularity input to the trigger, in order to mitigate pile-up effects and to reduce the background rates. In Phase-II, completely new read-out electronics will allow a digital processing of all LAr and Tile Calorimeter channels at full 40 MHz bunch-crossing frequency and a transfer of calibrated energy inputs to the trigger. Results from system design and performance of the developed read-out components, including fully functioning demonstrator systems already operated on the detector, will be reported. Furthermore, the current Forward Calorimeter (FCal) may suffer from signal degradation and argon bubbl...

  12. Optical Variability Properties of High Luminosity AGN Classes

    Indian Academy of Sciences (India)

    C. S. Stalin; Gopal-Krishna; Ram Sagar; Paul J. Wiita

    2004-03-01

    We present the results of a comparative study of the intra-night optical variability (INOV) characteristics of radio-loud and radio-quiet quasars, which involves a systematic intra-night optical monitoring of seven sets of high luminosity AGNs covering the redshift range ≃ 0.2 to ≃ 2.2. The sample, matched in the optical luminosity – redshift (-) plane, consists of seven radio-quiet quasars (RQQs), eight radio lobe-dominated quasars (LDQs), five radio core-dominated quasars (CDQs) and six BL Lac objects (BLs). Systematic CCD observations, aided by a careful data analysis procedure, have allowed us to detect INOV with amplitudes as low as about 1%. Present observations cover a total of 113 nights (720 hours) with only a single qusar monitored as continuously as possible on a given night. Considering the cases of only unambiguous detections of INOV we have estimated duty cycles (DCs) of 17%, 12%, 20% and 61% for RQQs, LDQs, CDQs, and BLs, respectively. The much lower amplitude and DC of INOV shown by RQQs compared to BLs may be understood in terms of their having optical synchrotron jets which are modestly misdirected from us. From our fairly extensive dataset, no general trend of a correlation between the INOVamplitude and the apparent optical brightness of the quasar is noticed. This suggests that the physical mechanisms of INOV and long term optical variability (LTOV) do not have a one-to-one relationship and different factors are involved. Also, the absence of a clear negative correlation between the INOV and LTOV characteristics of blazars of our sample points toward an inconspicuous contribution of accretion disk fluctuations to the observed INOV. The INOV duty cycle of the AGNs observed in this program suggests that INOV is associated predominantly with the highly polarized optical emission components. We also report new VLA imaging of two RQQs (1029 + 329 & 1252 + 020) in our sample which has yielded a 5 GHz detection in one of them (1252 + 020; 5GHz ≃ 1 mJy)

  13. Practical and foreseeable limitations in usable luminosity for the collider

    International Nuclear Information System (INIS)

    The present situation and possible short-term improvements of the panti p collider are discussed. A long-term plan, aiming at an increase in luminosity by an order of magnitude is then described. (orig.)

  14. Layered convection as the origin of Saturn's luminosity anomaly

    CERN Document Server

    Leconte, Jérémy; 10.1038/ngeo1791

    2013-01-01

    As they keep cooling and contracting, Solar System giant planets radiate more energy than they receive from the Sun. Applying the first and second principles of thermodynamics, one can determine their cooling rate, luminosity, and temperature at a given age. Measurements of Saturn's infrared intrinsic luminosity, however, reveal that this planet is significantly brighter than predicted for its age. This excess luminosity is usually attributed to the immiscibility of helium in the hydrogen-rich envelope, leading to "rains" of helium-rich droplets. Existing evolution calculations, however, suggest that the energy released by this sedimentation process may not be sufficient to resolve the puzzle. Here, we demonstrate using planetary evolution models that the presence of layered convection in Saturn's interior, generated, like in some parts of Earth oceans, by the presence of a compositional gradient, significantly reduces its cooling. It can explain the planet's present luminosity for a wide range of configurati...

  15. A mixture evolution scenario of AGN radio luminosity function

    CERN Document Server

    Yuan, Zunli; Zhou, Ming; Mao, Jirong

    2016-01-01

    We propose a mixture evolution scenario to model the evolution of the steep spectrum AGN (active galactic nuclear) radio luminosity function (RLF) based on a Bayesian method. In this scenario, the shape of RLF is determined together by the density and luminosity evolution. Our models indicate that the density evolution is positive until a redshift of $\\thicksim 0.9$ and then turns to be negative, while the luminosity evolution is positive to a higher redshift ($z \\thicksim 5$ for model B and $z \\thicksim 3.5$ for model C) and then turns to be negative. Our mixture evolution model works well, and the modeled RLFs are in good agreement with previous determinations. The mixture evolution scenario can naturally explain the luminosity dependent evolution of the RLFs.

  16. First Results from the Pixel Luminosity Telescope (PLT)

    CERN Document Server

    CMS Collaboration

    2015-01-01

    The Pixel Luminosity Telescope (PLT) is a silicon pixel detector dedicated to luminosity measurement at CMS. After a successful pilot run in 2012, the full PLT system, consisting of 48 pixel sensors mounted in 16 telescopes, eight on each side of CMS, was installed during LS1. The PLT provides luminosity measurements by using the ``fast-or'' capability of the pixel readout chips to find events where a hit is registered in all three sensors in a telescope, corresponding to a track from the interaction point. In addition, the full pixel data can be read out at a lower rate, allowing for measurements of efficiency, online monitoring of the data quality, and online analyses such as beamspot reconstruction, as well as enabling alternative techniques of luminosity measurement such as pixel cluster counting.

  17. Improvement to the D0 luminosity monitor constant

    International Nuclear Information System (INIS)

    The D0 experiment has previously calculated its luminosity using the visible cross section (luminosity monitor constant) for its Level 0 trigger, σL0 = 48.2 mb, based on the world average pp inelastic cross sections at √s = 1.8 TeV. The error on luminosity had been set at 12%. Recent studies using the MBR and DTUJET Monte Carlo event generators and unbiased D0 data samples have resulted in a more precise determination of the D0 luminosity monitor constant. The result, σL0 = 46.7 ± 2.5 mb, lowers the central value by 3.1% and reduces the error to 5.4%. 12 refs., 7 figs., 9 tabs

  18. the D0 Luminosity Monitor operations and performance

    Energy Technology Data Exchange (ETDEWEB)

    Prewitt, Michelle; /Rice U.

    2011-09-01

    The D0 Luminosity Monitor (LM) plays a crucial role in D0 physics analyses by providing the normalization for many cross section measurements. The detector consists of two sets of 24 scintillator wedges read out with photomultiplier tubes. The detector is located in the forward regions surrounding the beam pipe, covering a pseudo-rapidity range of 2.7 < |{eta}| < 4.4. The LM is sensitive to a large fraction of the total inelastic cross section and measures the luminosity by counting the number of empty proton-antiproton bunch crossings, using Poisson statistics to extract the instantaneous luminosity. The techniques used to convert the measurements made by the LM into the assessed luminosity will be discussed, as well as the performance and operational details of the detector.

  19. Measurement of ?? and ?e luminosities and polarizations at photon colliders

    International Nuclear Information System (INIS)

    Methods of ??, ?e luminosities measurement at photon colliders based on Compton scattering of laser photons on high energy electrons at linear colliders are considered. This is not a simple problem because photon have broad spectra and various kind of polarizations

  20. The Kinematics of the Lag-Luminosity Relationship

    Energy Technology Data Exchange (ETDEWEB)

    Salmonson, J D

    2004-03-17

    Herein I review the argument that kinematics, i.e. relativistic motions of the emitting source in gamma-ray bursts (GRBs), are the cause of the lag-luminosity relationship observed in bursts with known redshifts.

  1. ERL-Ring Type High Luminosity Charm Factory

    International Nuclear Information System (INIS)

    A high luminosity energy recovery linac-ring type electron-positron collider serving as super charm factory is proposed. It is shown that the design luminosity L=1035 cm-2s-1 and more can be achieved for center of mass energy √s=3.77 GeV. The physics potential of this machine in investigation for charmed particles properties is briefly discussed.

  2. On the Luminosity Distance and the Hubble Constant

    Directory of Open Access Journals (Sweden)

    Yuri Heymann

    2013-07-01

    Full Text Available By differentiating luminosity distance with respect to time using its standard formula we ?nd that the peculiar velocity is a time varying velocity of light. Therefore, a new de?nition of the luminosity distance is provided such that the peculiar velocity is equal to c. Using this de?nition a Hubble constant H0 = 67.3 km s?1 Mpc?1 is obtained from supernovae data.

  3. Physics at a High-Luminosity LHC with ATLAS

    OpenAIRE

    The ATLAS Collaboration

    2012-01-01

    The physics accessible at the high-luminosity phase of the LHC extends well beyond that of the earlier LHC program. This white paper, submitted as input to the Snowmass Community Planning Study 2013, contains preliminary studies of selected topics, spanning from Higgs boson studies to new particle searches and rare top quark decays. They illustrate the substantially enhanced physics reach with an increased integrated luminosity of 3000 fb-1, and motivate the planned upgrades of the LHC machin...

  4. When teaching: Out with magnitudes, in with monochromatic luminosities!

    OpenAIRE

    Verbunt, Frank

    2008-01-01

    The goal of this document is to illustrate that teaching the concepts of magnitudes is a needless complication in introductory astronomy courses, and that use of monochromatic luminosities, rather than arbitrarily defined magnitudes, leads to a large gain in transparency. This illustration is done through three examples: the Hertzsprung-Russell diagram, the cosmic distance ladder, and interstellar reddening. I provide conversion equations from the magnitude-based to the luminosity-based syste...

  5. Performance of the new high precision luminosity monitor of DELPHI

    International Nuclear Information System (INIS)

    The STIC calorimeter was installed in the DELPHI detector in 1994. The main goal is to measure the luminosity with an accuracy better than 0.1%. The calorimeter was built using the ''Shashlik'' technique. The light is collected by wavelength shifting fibers and readout by phototetrodes that can operate inside the magnetic field. The detector performance during the 1994-1995 data taking is presented. The different contributions to the systematic error on the luminosity measurement are discussed. (orig.)

  6. Precision of MPX detectors as LHC luminosity monitor

    International Nuclear Information System (INIS)

    A network consisting of MPX detectors based on Medipix2 silicon pixel devices were originally adapted for measuring the composition and spectral characteristics of the radiation field in the ATLAS experiment and its surroundings. We demonstrate that the MPX network, which consists of 16 MPX detectors, is a self-contained luminosity monitor system. As the MPX detectors are collecting data independently of the ATLAS data-recording chain, they provide independent measurements of the bunch-integrated ATLAS/LHC luminosity. In particular, the MPX detectors close enough to the primary interaction point are used to perform van der Meer calibration scans with good precision. Results from the luminosity monitoring are presented for 2012 data taken at √(s)=8 TeV proton-proton collisions. The characteristics of the LHC luminosity reduction are studied and the effects of beam-beam (burn-off) and beam-gas (single bunch) interactions are evaluated. The variations of the MPX luminosity measurements around the fitted curve lead to a relative uncertainty on the luminosity measurement below 0.3% for one minute time intervals.

  7. Precision of MPX detectors as LHC luminosity monitor

    Energy Technology Data Exchange (ETDEWEB)

    Sopczak, Andre; Ali, Babar; Benes, Petr; Bergmann, Benedikt; Biskup, Bartolomej; Caforio, Davide; Heijne, Erik; Pospisil, Stanislav; Seifert, Frank; Solc, Jaroslav; Suk, Michal; Turecek, Daniel; Vykydal, Zdenek [IEAP CTU in Prague (Czech Republic); Asbah, Nedaa; Leroy, Claude; Soueid, Paul [University of Montreal (Canada); Campbell, Michael; Nessi, Marzio [CERN (Switzerland); Kladiva, Edward [IEP SAS Kosice (Slovakia)

    2015-07-01

    A network consisting of MPX detectors based on Medipix2 silicon pixel devices were originally adapted for measuring the composition and spectral characteristics of the radiation field in the ATLAS experiment and its surroundings. We demonstrate that the MPX network, which consists of 16 MPX detectors, is a self-contained luminosity monitor system. As the MPX detectors are collecting data independently of the ATLAS data-recording chain, they provide independent measurements of the bunch-integrated ATLAS/LHC luminosity. In particular, the MPX detectors close enough to the primary interaction point are used to perform van der Meer calibration scans with good precision. Results from the luminosity monitoring are presented for 2012 data taken at √(s)=8 TeV proton-proton collisions. The characteristics of the LHC luminosity reduction are studied and the effects of beam-beam (burn-off) and beam-gas (single bunch) interactions are evaluated. The variations of the MPX luminosity measurements around the fitted curve lead to a relative uncertainty on the luminosity measurement below 0.3% for one minute time intervals.

  8. CONTRIBUTION OF THE ACCRETION DISK, HOT CORONA, AND OBSCURING TORUS TO THE LUMINOSITY OF SEYFERT GALAXIES: INTEGRAL AND SPITZER OBSERVATIONS

    International Nuclear Information System (INIS)

    We estimate the relative contributions of the supermassive black hole (SMBH) accretion disk, corona, and obscuring torus to the bolometric luminosity of Seyfert galaxies, using Spitzer mid-infrared (MIR) observations of a complete sample of 68 nearby active galactic nuclei (AGNs) from the INTEGRAL all-sky hard X-ray (HX) survey. This is the first HX-selected (above 15 keV) sample of AGNs with complementary high angular resolution, high signal-to-noise, MIR data. Correcting for the host galaxy contribution, we find a correlation between HX and MIR luminosities: L15μm∝L0.74±0.06HX. Assuming that the observed MIR emission is radiation from an accretion disk reprocessed in a surrounding dusty torus that subtends a solid angle decreasing with increasing luminosity (as inferred from the declining fraction of obscured AGNs), the intrinsic disk luminosity, LDisk, is approximately proportional to the luminosity of the corona in the 2-300 keV energy band, LCorona, with the LDisk/LCorona ratio varying by a factor of 2.1 around a mean value of 1.6. This ratio is a factor of ∼2 smaller than for typical quasars producing the cosmic X-ray background. Therefore, over three orders of magnitude in luminosity, HX radiation carries a large, and roughly comparable, fraction of the bolometric output of AGNs. We estimate the cumulative bolometric luminosity density of local AGNs at ∼(1-3) × 1040 erg s–1 Mpc–3. Finally, the Compton temperature ranges between kTc ≈ 2 and ≈6 keV for nearby AGNs, compared to kTc ≈ 2 keV for typical quasars, confirming that radiative heating of interstellar gas can play an important role in regulating SMBH growth.

  9. Upgrade plans for the Hadronic-Endcap Calorimeter of ATLAS for the high luminosity stage of the LHC

    CERN Document Server

    Ahmadov, Faig; The ATLAS collaboration; Cadabeschi, Mircea; Cheplakov, Alexander; Dominguez, Ruben; Fischer, Alexander; Habring, Jörg; Hambarzumjan, Armen; Javadov, Namig; Kiryunin, Andrey; Kurchaninov, Leonid; Langstaff, Roy; Lenckowski, Mark; Menke, Sven; Molinas Conde, Ignacio; Nagel, Martin; Oberlack, Horst; Raymond, Michel; Reimann, Olaf; Schacht, Peter; Strizenec, Pavol; Vogt, Sven; Wichmann, Giselher

    2015-01-01

    The expected increase of the instantaneous luminosity of a factor seven and of the total integrated luminosity by a factor 3-5 at the second phase of the upgraded high luminosity LHC compared to the design goals for LHC makes it necessary to re-evaluate the radiation hardness of the read-out electronics of the ATLAS Hadronic Endcap Calorimeter. The current cold electronics made of GaAs ASICs have been tested with neutron and proton beams to study their degradation under irradiation and the effect it would have on the ATLAS physics programme. New, more radiation hard technologies which could replace the current amplifiers have been studied as well: SiGe bipolar, Si CMOS FET and GaAs FET transistors have been irradiated with neutrons and protons with fluences up to ten times the total expected fluences for ten years of running of the high luminosity LHC. The performance measurements of the current read-out electronics and potential future technologies and expected performance degradations under high luminosity ...

  10. High-Luminosity Large Hadron Collider (HL-LHC) Preliminary Design Report

    CERN Document Server

    Béjar Alonso, I; Brüning, O; Lamont, M; Rossi, L

    2015-01-01

    The Large Hadron Collider (LHC) is one of the largest scientific instruments ever built. Since opening up a new energy frontier for exploration in 2010, it has gathered a global user community of about 7,000 scientists working in fundamental particle physics and the physics of hadronic matter at extreme temperature and density. To sustain and extend its discovery potential, the LHC will need a major upgrade in the 2020s. This will increase its luminosity (rate of collisions) by a factor of five beyond the original design value and the integrated luminosity (total collisions created) by a factor ten. The LHC is already a highly complex and exquisitely optimised machine so this upgrade must be carefully conceived and will require about ten years to implement. The new configuration, known as High Luminosity LHC (HL-LHC), will rely on a number of key innovations that push accelerator technology beyond its present limits. Among these are cutting-edge 11-12 tesla superconducting magnets, compact superconducting cav...

  11. MID-IR LUMINOSITIES AND UV/OPTICAL STAR FORMATION RATES AT z < 1.4

    International Nuclear Information System (INIS)

    Ultraviolet (UV) nonionizing continuum and mid-infrared (IR) emission constitute the basis of two widely used star formation (SF) indicators at intermediate and high redshifts. We study 2430 galaxies with z 10-1012 Lsun). We show that the IR luminosity can be estimated from the UV and optical photometry to within a factor of 2, implying that most z IR>1011 Lsun, yet with little current SF. For them a reasonable amount of dust absorption of stellar light (but presumably higher than in nearby early-type galaxies) is sufficient to produce the observed levels of IR, which includes a large contribution from intermediate and old stellar populations. In our sample, which contains very few ultraluminous IR galaxies, optical and X-ray active galactic nuclei do not contribute on average more than ∼50% to the mid-IR luminosity, and we see no evidence for a large population of 'IR excess' galaxies.

  12. A luminosity measurement at LEP using the L3 detector

    Energy Technology Data Exchange (ETDEWEB)

    Koffeman, E.N.

    1996-06-25

    To perform high precision measurements at particle colliders it is crucial to know the exact intensity of the colliding beams. In particle physics this quantity is generally referred to as the luminosity. The determination of the luminosity in one of the experiments (L3) is the topic of this thesis. The implementation and the use of a silicon strip detector in L3, will be described in detail. In chapter one the most important parameters measured at LEP are discussed, preceded by a short introduction to the Standard Model. The process generally used for luminosity measurements in electron positron colliders is small angle Bhabha scattering. This process is discussed at the end of chapter one. In chapter two the characteristics of the collider and the L3 experiment are given. Together with the signature of the small angle Bhabha scattering, these experimental conditions determine the specifications for the design of the luminosity monitor. The general features of silicon strip detectors for their application in high energy physics are presented in chapter three. Some special attention is given to the behaviour of the sensors used for the tracking detector in the luminosity monitor. The more specific design details of the luminosity monitor are constricted to chapter four. In chapter five the conversion from detector signals into ccordinates relevant for the analysis is explained. The selection of the small angle Bhabha scattering events and the subsequent determination of the luminosity, are presented in chapter six. Systematic uncertainties are carefully studied. Important for a good understanding of the Bhabha selection are the events where a photon is produced in the scattering process. These events are separately studied. In chapter seven a comparison is presented between the radiative events observed in the data and their modelling in the Bhlumi Monte Carlo programme. (orig.).

  13. A luminosity measurement at LEP using the L3 detector

    International Nuclear Information System (INIS)

    To perform high precision measurements at particle colliders it is crucial to know the exact intensity of the colliding beams. In particle physics this quantity is generally referred to as the luminosity. The determination of the luminosity in one of the experiments (L3) is the topic of this thesis. The implementation and the use of a silicon strip detector in L3, will be described in detail. In chapter one the most important parameters measured at LEP are discussed, preceded by a short introduction to the Standard Model. The process generally used for luminosity measurements in electron positron colliders is small angle Bhabha scattering. This process is discussed at the end of chapter one. In chapter two the characteristics of the collider and the L3 experiment are given. Together with the signature of the small angle Bhabha scattering, these experimental conditions determine the specifications for the design of the luminosity monitor. The general features of silicon strip detectors for their application in high energy physics are presented in chapter three. Some special attention is given to the behaviour of the sensors used for the tracking detector in the luminosity monitor. The more specific design details of the luminosity monitor are constricted to chapter four. In chapter five the conversion from detector signals into ccordinates relevant for the analysis is explained. The selection of the small angle Bhabha scattering events and the subsequent determination of the luminosity, are presented in chapter six. Systematic uncertainties are carefully studied. Important for a good understanding of the Bhabha selection are the events where a photon is produced in the scattering process. These events are separately studied. In chapter seven a comparison is presented between the radiative events observed in the data and their modelling in the Bhlumi Monte Carlo programme. (orig.)

  14. On the Radio and Optical Luminosity Evolution of Quasars

    Energy Technology Data Exchange (ETDEWEB)

    Singal, J.; /KIPAC, Menlo Park /SLAC; Petrosian, V.; /KIPAC, Menlo Park /SLAC /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept.; Lawrence, A.; /Edinburgh U., Inst. Astron.; Stawarz, L.; /JAXA, Sagamihara /Jagiellonian U., Astron. Observ.

    2011-05-20

    We calculate simultaneously the radio and optical luminosity evolutions of quasars, and the distribution in radio loudness R defined as the ratio of radio and optical luminosities, using a flux limited data set containing 636 quasars with radio and optical fluxes from White et al. We first note that when dealing with multivariate data it is imperative to first determine the true correlations among the variables, not those introduced by the observational selection effects, before obtaining the individual distributions of the variables. We use the methods developed by Efron and Petrosian which are designed to obtain unbiased correlations, distributions, and evolution with redshift from a data set truncated due to observational biases. It is found that as expected the population of quasars exhibits strong positive correlation between the radio and optical luminosities and that this correlation deviates from a simple linear relation in a way indicating that more luminous quasars are more radio loud. We also find that there is a strong luminosity evolution with redshift in both wavebands, with significantly higher radio than optical evolution. We conclude that the luminosity evolution obtained by arbitrarily separating the sources into radio loud (R > 10) and radio quiet (R < 10) populations introduces significant biases that skew the result considerably. We also construct the local radio and optical luminosity functions and the density evolution. Finally, we consider the distribution of the radio loudness parameter R obtained from careful treatment of the selection effects and luminosity evolutions with that obtained from the raw data without such considerations. We find a significant difference between the two distributions and no clear sign of bi-modality in the true distribution. Our results indicate therefore, somewhat surprisingly, that there is no critical switch in the efficiency of the production of disk outflows/jets between very radio quiet and very radio loud quasars, but rather a smooth transition. Also, this efficiency seems higher for the high-redshift and more luminous sources in the considered sample.

  15. Performance evaluation and optimization of the luminosity detector ALFA

    CERN Document Server

    Jakobsen, Sune; Grafström, P; Joram, C

    2010-01-01

    The startup of the LHC (Large Hadron Collider) has initialized a new era in particle physics. The standard model of particle physics has for the last 40 years with tremendous success described all measurements with phenomenal precision. The experiments at the LHC will test the standard model in a new energy regime. To normalize the measurements and understand the potential discoveries of the LHC experiments it is often crucial to know the interaction rate - the absolute luminosity. The ATLAS (A Toroidal LHC ApparatuS) detector will measure luminosity by numerous methods. But for most of the methods only the relative luminosity is measured with good precision. The absolute scale has to be provided from elsewhere. Therefore ATLAS plans to measure the flux of protons scattered under very small angles as this flux relates directly and with good precision to the absolute luminosity. This will be done by the ALFA (Absolute Luminosity For ATLAS) detector. The detectors will be positioned about 240 m from the interac...

  16. The Sun's luminosity over a complete solar cycle

    International Nuclear Information System (INIS)

    The Active Cavity Radiometer Irradiance Monitor (ACRIM I), an instrument carried on NASA's Solar Maximum Mission satellite, measured the Sun's luminosity (total power outflow) from early 1980 to late 1989. Here we present the first account of the complete ACRIM I data set, and give evidence confirming our previous suggestion that solar luminosity varies with the 11-year solar cycle. As previously reported, this slow variation closely follows statistical measures of the distribution of magnetic and photospheric features on the sun's surface. But there was an exception to this correlation in the form of a remarkable irradiance excess during 1980, at about the time of the sunspot maximum solar cycle 21. The linkage, over a whole cycle, of luminosity variation to photospheric activity suggests the existence of an unknown physical mechanism other than the thermal diffusion model that explains luminosity deficits due to sunspots. Luminosity models connecting total irradiance to global indicators of solar activity, such as the equivalent width of the 1,083-nm helium line, are consistent with the gross features of the variability, but fail to account for the 1980 irradiance excess. (author)

  17. LHCb: LHCb Muon System Performance at High Luminosity

    CERN Multimedia

    Pinci, D

    2013-01-01

    The LHCb detector was conceived to operate with an average Luminosity of $2 \\times 10^{32}$ cm$^{-2}$ s$^{-1}$. During the last year of LHC run, the whole apparatus has shown to be able to perfectly acquire and manage data produced at a Luminosity as high as $4 \\times 10^{32}$ cm$^{-2}$ s$^{-1}$. In these conditions, all sub-detectors operated at average particle rates higher than the design ones and in particular the Multi-Wire Proportional Chambers equipping the Muon System had to sustain a particle rate as high as 250 kHz/cm$^{2}$. In order to study the possibility of increasing the Luminosity of operation of the whole experiment several tests were performed. The effective beam Luminosity at the interaction point of LHCb was increased in several steps up to $10^{33}$ cm$^{-2}$ s$^{-1}$ and in each step the behavior of all the detectors in the Muon System was recorded. The data analysis has allowed to study the performance of the Muon System as a function of the LHC Luminosity and the results are r...

  18. Does the obscured AGN fraction really depend on luminosity?

    CERN Document Server

    Sazonov, Sergey; Krivonos, Roman

    2015-01-01

    We use a sample of 151 local non-blazar AGN selected from the INTEGRAL all-sky hard X-ray survey to investigate if the observed declining trend of the fraction of obscured (i.e. showing X-ray absorption) AGN with increasing luminosity is mostly an intrinsic or selection effect. Using a torus-obscuration model, we demonstrate that in addition to negative bias, due to absorption in the torus, in finding obscured AGN in hard X-ray flux limited surveys, there is also positive bias in finding unobscured AGN, due to Compton reflection in the torus. These biases can be even stronger taking into account plausible intrinsic collimation of hard X-ray emission along the axis of the obscuring torus. Given the AGN luminosity function, which steepens at high luminosities, these observational biases lead to a decreasing observed fraction of obscured AGN with increasing luminosity even if this fraction has no intrinsic luminosity dependence. We find that if the central hard X-ray source in AGN is isotropic, the intrinsic (i....

  19. On the Luminosity Dependence of the Galaxy Pairwise Velocity Dispersion

    CERN Document Server

    Tinker, J L; Weinberg, D H; Warren, M S; Tinker, Jeremy L.; Norberg, Peder; Weinberg, David H.; Warren, Michael S.

    2006-01-01

    (Abridged) We make predictions for the pairwise velocity dispersion (PVD) of galaxies with models that are constrained to match the projected correlation function and luminosity function of galaxies in the Two-Degree Field Galaxy Redshift Survey (2dFGRS). We use these data to constrain the halo occupation distribution (HOD), then calculate the PVD by populating the halos of a high resolution N-body simulation. We examine the luminosity and scale dependence of the predicted PVD. At r3 Mpc/h, we find that the PVD decreases with increasing galaxy luminosity. This result is mostly driven by the fraction of satellite galaxies f_sat, which is well-constrained by the correlation function. We find f_sat~25% for galaxies fainter than L_star, while for brighter galaxies the satellite fraction rapidly declines, creating the decrease in the PVD with luminosity. At r=1 Mpc/h, the PVD has no dependence on luminosity because satellite galaxies dominate the statistics for all objects. Recent measurements of the PVD in Fourie...

  20. An early separation scheme for the LHC luminosity upgrade

    CERN Document Server

    Sterbini, G

    2010-01-01

    The present document is organized in five chapters. In the first chapter the framework of the study is described, developing the motivations, the goals and the requirements for the LHC Luminosity Upgrade. We analyze the need for the crossing angle and its impact on the peak luminosity of the collider. After having introduced the Early Separation Scheme, we explain how it may overcome some limitations of the present machine. We compare the nominal LHC crossing scheme with the proposed one underlining its potential in terms of performance and its issues with respect to the integration in the detectors. An analysis of the integrated magnetic field required is given. In the second chapter we introduce one of the most powerful aspect of the scheme: the luminosity leveling. After the description of the physical model adopted, we compare the results of its analytical and numerical solutions. All the potential improvement due to the Early Separation Scheme are shown on the luminosity plane (peak luminosity versus int...

  1. The Luminosity Function of Galaxies in SDSS Commissioning Data

    CERN Document Server

    Blanton, M R; Eisenstein, D J; Loveday, J; Strauss, M A; Subba-Rao, M; Weinberg, D H; Anderson, J E; Annis, J; Bahcall, Neta A; Bernardi, M; Brinkmann, J; Brunner, R J; Burles, S M; Carey, L D; Castander, F J; Connolly, A J; Csabai, I; Doi, M; Finkbeiner, D; Friedman, S; Frieman, Joshua A; Fukugita, M; Gunn, J E; Hennessy, G S; Hindsley, R B; Ichikawa, T; Ivezic, Z; Kent, S; Knapp, G R; Lamb, D Q; French-Leger, R; Long, D C; Lupton, R H; McKay, T A; Meiksin, A; Merelli, A; Munn, J A; Narayanan, V K; Newcomb, M; Nichol, R C; Okamura, S; Owen, R; Pier, J R; Pope, A C; Postman, M; Quinn, M; Rockosi, C M; Schlegel, D J; Schneider, D P; Shimasaku, K; Siegmund, W A; Smee, S; Snir, Y; Stoughton, C; Stubbs, C; Szalay, A S; Szokoly, G P; Thakar, A R; Tremonti, C A; Tucker, D L; Uomoto, A; Vanden Berk, Daniel E; Vogeley, M S; Waddell, P; Yanny, B; Yasuda, N; York, D G

    2001-01-01

    During commissioning observations, the Sloan Digital Sky Survey (SDSS) has produced one of the largest existing galaxy redshift samples selected from CCD images. Using 11,275 galaxies complete to r^* = 17.6 over 140 square degrees, we compute the luminosity function of galaxies in the r^* band over a range -23 < M < -16 (for h=1). The result is well-described by a Schechter function with parameters phi_* = 0.0146 +/- 0.0012 h^3 Mpc^{-3}, M_* = -20.83 +/- 0.03, and alpha = -1.20 +/- 0.03. The implied luminosity density in r^* is j = (2.6 +/- 0.3) x 10^8 h L_sun Mpc^{-3}. The surface brightness selection threshold has a negligible impact for M < -18. We measure the luminosity function in the u^*, g^*, i^*, and z^* bands as well; the slope at low luminosities ranges from alpha=-1.35 to alpha=-1.2. We measure the bivariate distribution of r^* luminosity with half-light surface brightness, intrinsic color, and morphology. High surface brightness, red, highly concentrated galaxies are on average more lumin...

  2. The galaxy luminosity function and the Local Hole

    Science.gov (United States)

    Whitbourn, J. R.; Shanks, T.

    2016-03-01

    Whitbourn & Shanks (2014) have reported evidence for a local void underdense by ≈15% extending to 150-300h-1Mpc around our position in the Southern Galactic Cap (SGC). Assuming a local luminosity function they modelled K- and r-limited number counts and redshift distributions in the 6dFGS/2MASS and SDSS redshift surveys and derived normalised n(z) ratios relative to the standard homogeneous cosmological model. Here we test further these results using maximum likelihood techniques that solve for the galaxy density distributions and the galaxy luminosity function simultaneously. We confirm the results from the previous analysis in terms of the number density distributions, indicating that our detection of the `Local Hole' in the SGC is robust to the assumption of either our previous, or newly estimated, luminosity functions. However, there are discrepancies with previously published K and r band luminosity functions. In particular the r-band luminosity function has a steeper faint end slope than the r0.1 results of Blanton et al. (2003) but is consistent with the r0.1 results of Montero-Dorta & Prada (2009); Loveday et al. (2012).

  3. Models of the quasar population. I. A new luminosity function

    International Nuclear Information System (INIS)

    A new functional form for the quasar luminosity function is tested using recent observational results for both bright and faint quasar count and redshift distributions. The form is of a fairly general type based on three free parameters and allows for quasars to undergo a combination of luminosity evolution and luminosity-dependent density evolution; an advantage to this approach is that it does not constrain quasars to follow a single type of evolution. Models of pure luminosity evolution or luminosity-dependent density evolution can be constructed, but the apparent magnitude distribution of observed quasars is best fitted by a combination model. The combination model also gives the correct redshift distribution for quasars with redshifts less than three and predicts that quasars brighter than B = 22 provide a 2-10 keV X-ray flux that is equal to 32 percent of the observed X-ray background. However, the model is flawed in that it predicts more high-redshift quasars than are observed. 45 references

  4. The galaxy luminosity function and the Local Hole

    CERN Document Server

    Whitbourn, J R

    2016-01-01

    Whitbourn & Shanks (2014) have reported evidence for a local void underdense by ~15% extending to 150-300h-1Mpc around our position in the Southern Galactic Cap (SGC). Assuming a local luminosity function they modelled K- and r-limited number counts and redshift distributions in the 6dFGS/2MASS and SDSS redshift surveys and derived normalised n(z) ratios relative to the standard homogeneous cosmological model. Here we test further these results using maximum likelihood techniques that solve for the galaxy density distributions and the galaxy luminosity function simultaneously. We confirm the results from the previous analysis in terms of the number density distributions, indicating that our detection of the 'Local Hole' in the SGC is robust to the assumption of either our previous, or newly estimated, luminosity functions. However, there are discrepancies with previously published K and r band luminosity functions. In particular the r-band luminosity function has a steeper faint end slope than the r0.1 re...

  5. The luminosity function for different morphological types in the CfA Redshift Survey

    Science.gov (United States)

    Marzke, Ronald O.; Geller, Margaret J.; Huchra, John P.; Corwin, Harold G., Jr.

    1994-01-01

    We derive the luminosity function for different morphological types in the original CfA Redshift Survey (CfA1) and in the first two slices of the CfA Redshift Survey Extension (CfA2). CfA1 is a complete sample containing 2397 galaxies distributed over 2.7 steradians with m(sub z) less than or equal 14.5. The first two complete slices of CfA2 contain 1862 galaxies distributed over 0.42 steradians with m(sub z)=15.5. The shapes of the E-S0 and spiral luminosity functions (LF) are indistinguishable. We do not confirm the steeply decreasing faint end in the E-S0 luminosity function found by Loveday et al. for an independent sample in the southern hemisphere. We demonstrate that incomplete classification in deep redshift surveys can lead to underestimates of the faint end of the elliptical luminosity function and could be partially responsible for the difference between the CfA survey and other local field surveys. The faint end of the LF for the Magellanic spirals and irregulars is very steep. The Sm-Im luminosity function is well fit by a Schechter function with M*=-18.79, alpha=-1.87, and phi*=0.6x10(exp -3) for M(sub z) less than or equal to -13. These galaxies are largely responsible for the excess at the faint end of the general CfA luminosity function. The abundance of intrinsically faint, blue galaxies nearby affects the interpretation of deep number counts. The dwarf population increases the expected counts at B=25 in a no-evolution, q(sub 0)=0.05 model by a factor of two over standard no-evolution estimates. These dwarfs change the expected median redshift in deep redshift surveys by less than 10 percent . Thus the steep Sm-Im LF may contribute to the reconciliation of deep number counts with deep redshift surveys.

  6. CLIC crab cavity design optimisation for maximum luminosity

    International Nuclear Information System (INIS)

    The bunch size and crossing angle planned for CERN's compact linear collider CLIC dictate that crab cavities on opposing linacs will be needed to rotate bunches of particles into alignment at the interaction point if the desired luminosity is to be achieved. Wakefield effects, RF phase errors between crab cavities on opposing linacs and unpredictable beam loading can each act to reduce luminosity below that anticipated for bunches colliding in perfect alignment. Unlike acceleration cavities, which are normally optimised for gradient, crab cavities must be optimised primarily for luminosity. Accepting the crab cavity technology choice of a 12 GHz, normal conducting, travelling wave structure as explained in the text, this paper develops an analytical approach to optimise cell number and iris diameter.

  7. Report of the Working Group on High Luminosities at LEP

    International Nuclear Information System (INIS)

    The availability of an order-of-magnitude increase in the luminosity of LEP (CERN's Large Electron-Positron Collider) can dramatically increase its physics output. With the help of a pretzel scheme, it should be possible to increase the peak luminosity beyond 1032 cm-2 s-1 at the Z energy and to significantly increase the luminosity around the W-pari threshold. This report spells out the physics possibilities opened up by the availability of several 107Z events. The three domains of physics that benefit mostly from this abundance are very accurate measurements of Standard Model parameters, rare decays of the Z, and the physics of fermion-antifermion states such as B physics. The possibilities and implications for the machine and the experiments are presented. The physics possibilities are explored and compared with those at other accelerators. (orig.)

  8. Evidence for steep luminosity functions in clusters of galaxies

    CERN Document Server

    De Propris, R; Harris, W E; McClure, R D; De Propris, R; Pritchet, C J; Harris, W E; McClure, R D

    1995-01-01

    Luminosity Functions have been obtained for very faint dwarf galaxies in the cores of four rich clusters of galaxies (Abell 2052, 2107, 2199 and 2666). It is found that the luminosity function of dwarf galaxies rises very steeply in these clusters, with a power-law slope of \\alpha -2.2 (down to absolute limiting magnitudes M_I = -13 and M_B = -11 for H_0 = 75 km/s/Mpc). A steepening of the luminosity function at faint magnitudes may in fact be a common feature of both cluster and field populations. Such a result may explain the observed excess counts of faint, intermediate redshift galaxies in the Universe, without resorting to more exotic phenomena. An alternate explanation is that star formation in dwarf galaxies is less affected by gas loss in the richest clusters, because of the dense, hot intracluster medium found in such environments.

  9. ATLAS Future Plans: Upgrade and the Physics with High Luminosity

    Directory of Open Access Journals (Sweden)

    Rajagopalan S.

    2013-05-01

    Full Text Available The ATLAS experiment is planning a series of detector upgrades to cope with the planned increases in instantaneous luminosity and multiple interactions per crossing to maintain its physics capabilities. During the coming decade, the Large Hadron Collider will collide protons on protons at a center of mass energy up to 14 TeV with luminosities steadily increasing in a phased approach to over 5 × 1034 cm−2s−1. The resulting large data sets will significantly enhance the physics reach of the ATLAS detector building on the recent discovery of the Higgs-like boson. The planned detector upgrades being designed to cope with the increasing luminosity and its impact on the ATLAS physics program will be discussed.

  10. AGN Broad Line Regions Scale with Bolometric Luminosity

    CERN Document Server

    Trippe, Sascha

    2015-01-01

    The masses of supermassive black holes in active galactic nuclei (AGN) can be derived spectroscopically via virial mass estimators based on selected broad optical/ultraviolet emission lines. These estimates commonly use the line width as a proxy for the gas speed and the monochromatic continuum luminosity as a proxy for the radius of the broad line region. However, if the size of the broad line region scales with bolometric rather than monochromatic AGN luminosity, mass estimates based on different emission lines will show a systematic discrepancy which is a function of the color of the AGN continuum. This has actually been observed in mass estimates based on H-alpha / H-beta and C IV lines, indicating that AGN broad line regions indeed scale with bolometric luminosity. Given that this effect seems to have been overlooked as yet, currently used single-epoch mass estimates are likely to be biased.

  11. Contribution of the accretion disk, hot corona, and obscuring torus to the luminosity of Seyfert galaxies: INTEGRAL and Spitzer observations

    CERN Document Server

    Sazonov, S; Goulding, A D; Hickox, R C; Gorjian, V; Werner, M W; Churazov, E; Krivonos, R; Revnivtsev, M; Sunyaev, R; Jones, C; Murray, S S; Vikhlinin, A; Fabian, A C; Forman, W R

    2012-01-01

    We estimate the relative contributions of the supermassive black hole (SMBH) accretion disk, corona, and obscuring torus to the bolometric luminosity of Seyfert galaxies, using Spizter mid-infrared (MIR) observations of a complete sample of 68 nearby active galactic nuclei from the INTEGRAL all-sky hard X-ray (HX) survey. This is the first HX-selected (above 15 keV) sample of AGNs with complementary high angular resolution, high signal to noise, MIR data. Correcting for the host galaxy contribution, we find a correlation between HX and MIR luminosities: L_MIR L_HX^(0.74+/-0.06). Assuming that the observed MIR emission is radiation from an accretion disk reprocessed in a surrounding dusty torus that subtends a solid angle decreasing with increasing luminosity (as inferred from the declining fraction of obscured AGNs), the intrinsic disk luminosity, L_D, is approximately proportional to the luminosity of the corona in the 2-300 keV energy band, L_C, with the L_D/L_C ratio varying by a factor of 2.1 around a mea...

  12. MODELING THE RED SEQUENCE: HIERARCHICAL GROWTH YET SLOW LUMINOSITY EVOLUTION

    International Nuclear Information System (INIS)

    We explore the effects of mergers on the evolution of massive early-type galaxies by modeling the evolution of their stellar populations in a hierarchical context. We investigate how a realistic red sequence population set up by z ? 1 evolves under different assumptions for the merger and star formation histories, comparing changes in color, luminosity, and mass. The purely passive fading of existing red sequence galaxies, with no further mergers or star formation, results in dramatic changes at the bright end of the luminosity function and color-magnitude relation. Without mergers there is too much evolution in luminosity at a fixed space density compared to observations. The change in color and magnitude at a fixed mass resembles that of a passively evolving population that formed relatively recently, at z ? 2. Mergers among the red sequence population ('dry mergers') occurring after z = 1 build up mass, counteracting the fading of the existing stellar populations to give smaller changes in both color and luminosity for massive galaxies. By allowing some galaxies to migrate from the blue cloud onto the red sequence after z = 1 through gas-rich mergers, younger stellar populations are added to the red sequence. This manifestation of the progenitor bias increases the scatter in age and results in even smaller changes in color and luminosity between z = 1 and z = 0 at a fixed mass. The resultant evolution appears much slower, resembling the passive evolution of a population that formed at high redshift (z ? 3-5), and is in closer agreement with observations. We conclude that measurements of the luminosity and color evolution alone are not sufficient to distinguish between the purely passive evolution of an old population and cosmologically motivated hierarchical growth, although these scenarios have very different implications for the mass growth of early-type galaxies over the last half of cosmic history.

  13. On the origin of the correlations between the accretion luminosity and emission line luminosities in pre-main-sequence stars

    Science.gov (United States)

    Mendiguta, I.; Oudmaijer, R. D.; Rigliaco, E.; Fairlamb, J. R.; Calvet, N.; Muzerolle, J.; Cunningham, N.; Lumsden, S. L.

    2015-09-01

    Correlations between the accretion luminosity and emission line luminosities (Lacc and Lline) of pre-main-sequence (PMS) stars have been published for many different spectral lines, which are used to estimate accretion rates. Despite the origin of those correlations is unknown, this could be attributed to direct or indirect physical relations between the emission line formation and the accretion mechanism. This work shows that all (near-UV/optical/near-IR) Lacc-Lline correlations are the result of the fact that the accretion luminosity and the stellar luminosity (L*) are correlated, and are not necessarily related with the physical origin of the line. Synthetic and observational data are used to illustrate how the Lacc-Lline correlations depend on the Lacc-L* relationship. We conclude that because PMS stars show the Lacc-L* correlation immediately implies that Lacc also correlates with the luminosity of all emission lines, for which the Lacc-Lline correlations alone do not prove any physical connection with accretion but can only be used with practical purposes to roughly estimate accretion rates. When looking for correlations with possible physical meaning, we suggest that Lacc/L* and Lline/L* should be used instead of Lacc and Lline. Finally, the finding that Lacc has a steeper dependence on L* for T Tauri stars than for intermediate-mass Herbig Ae/Be stars is also discussed. That is explained from the magnetospheric accretion scenario and the different photospheric properties in the near-UV.

  14. On the origin of the correlations between the accretion luminosity and emission line luminosities in pre-main sequence stars

    CERN Document Server

    Mendiguta, I; Rigliaco, E; Fairlamb, J R; Calvet, N; Muzerolle, J; Cunningham, N; Lumsden, S L

    2015-01-01

    Correlations between the accretion luminosity and emission line luminosities (L_acc and L_line) of pre-main sequence (PMS) stars have been published for many different spectral lines, which are used to estimate accretion rates. Despite the origin of those correlations is unknown, this could be attributed to direct or indirect physical relations between the emission line formation and the accretion mechanism. This work shows that all (near-UV/optical/near-IR) L_acc-L_line correlations are the result of the fact that the accretion luminosity and the stellar luminosity (L_star) are correlated, and are not necessarily related with the physical origin of the line. Synthetic and observational data are used to illustrate how the L_acc-L_line correlations depend on the L_acc-L_star relationship. We conclude that because PMS stars show the L_acc-L_star correlation immediately implies that L_acc also correlates with the luminosity of all emission lines, for which the L_acc-L_line correlations alone do not prove any phy...

  15. STUDY OF THE RELATIVE LHC BUNCH POPULATIONS FOR LUMINOSITY CALIBRATION

    CERN Document Server

    Anders, G; Balagura, V; Barschel, C; Belohrad, D; Burkhardt, H; Ferro-Luzzi, M; Gabaldon, C; Gagliardi, M; Gras, J J; Hopchev, P; Jeff, A; Kozanecki, W; Ludwig, M; Marlow, D; Oyama, K; Panman, J; White, S; Zuranski, A

    2012-01-01

    An important aspect of luminosity calibration measurements is the bunch population product normalization. In the case of the LHC, the treatment of this normalization can be split into three subjects: the total current measurement, the corrections from the non-perfect longitudinal distribution and the relative amplitude of the individual bunch populations. In this note, the last item is discussed in detail and in the context of the 2010 and 2011 luminosity calibration measurements performed for each LHC Interaction Point. The various measurement methods of the relative bunch populations are reviewed and the impact of their uncertainties on the cross section normalization are analyzed.

  16. Luminosities of Barred and Unbarred S0 Galaxies

    OpenAIRE

    Bergh, Sidney Van Den

    2012-01-01

    Lenticular galaxies with M_B < -21.5 are almost exclusively unbarred, whereas both barred and unbarred objects occur at fainter luminosity levels. This effect is observed both for objects classified in blue light, and for those that were classified in the infrared. This result suggests that the most luminous (massive) S0 galaxies find it difficult to form bars. As a result the mean luminosity of unbarred lenticular galaxies in both B and IR light is observed to be ~0.4 mag brighter than than ...

  17. Online calculation of the Tevatron collider luminosity using accelerator instrumentation

    International Nuclear Information System (INIS)

    The luminosity of a collision region may be calculated if one understands the lattice parameters and measures the beam intensities, the transverse and longitudinal emittances, and the individual proton and antiproton beam trajectories (space and time) through the collision region. This paper explores an attempt to make this calculation using beam instrumentation during Run 1b of the Tevatron. The instrumentation used is briefly described. The calculations and their uncertainties are compared to luminosities calculated independently by the Collider Experiments (CDF and D0)

  18. Luminosity dependence of the quasar clustering from SDSS NBCKDE catalogue

    International Nuclear Information System (INIS)

    We study the clustering of quasars from the SDSS NBCKDE catalogue of photometrically selected quasar candidates (SDSS DR6). Dividing our sample with 0.8phot<2.2 onto three luminosity bins we have found no evidence for luminosity dependence of the quasar clustering. It is consistent with the models of the quasar formation, in which bring and faint quasars are assumed to be similar sources, hosted by dark matter halos of similar masses, but observed at different stages of their evolution

  19. On the Luminosity Dependence of the Galaxy Pairwise Velocity Dispersion

    OpenAIRE

    Tinker, Jeremy L.; Norberg, Peder; Weinberg, David H.; Warren, Michael S

    2006-01-01

    (Abridged) We make predictions for the pairwise velocity dispersion (PVD) of galaxies with models that are constrained to match the projected correlation function and luminosity function of galaxies in the Two-Degree Field Galaxy Redshift Survey (2dFGRS). We use these data to constrain the halo occupation distribution (HOD), then calculate the PVD by populating the halos of a high resolution N-body simulation. We examine the luminosity and scale dependence of the predicted PVD. At r3 Mpc/h, w...

  20. System Design of the ATLAS Absolute Luminosity Monitor

    CERN Document Server

    Anghinolfi, Francis; Franz, Sebastien; Iwanski, W; Lundberg, B; PH-EP

    2007-01-01

    The ATLAS absolute luminosity monitor is composed of 8 roman pots symmetrically located in the LHC tunnel. Each pot contains 23 multi anode photomultiplier tubes, and each one of those is fitted with a front-end assembly called PMF. A PMF provides the high voltage biasing of the tube, the frontend readout chip and the readout logic in a very compact arrangement. The 25 PMFs contained in one roman pot are connected to a motherboard used as an interface to the backend electronics. The system allows to configure the front-end electronics from the ATLAS detector control system and to transmit the luminosity data over Slink.

  1. Tracking with CVD diamond radiation sensors at high luminosity colliders

    International Nuclear Information System (INIS)

    Recent progress on developing diamond-based sensors for vertex detection at high luminosity hadron colliders is described. Measurements of the performance of diamond sensors after irradiation to fluences of up to 5 x 1015 hadrons/cm2 are shown. These indicate that diamond sensors will operate at distances as close as 5 cm from the interaction point at the Large Hadron Collider (LHC) for many years at full luminosity without significant degradation in performance. Measurements of the quality of the signals from diamond sensors as well as spatial uniformity are presented. Test beam results on measurements of diamond-based microstrip and pixels devices are described

  2. Fast and precise luminosity measurement at the international linear collider

    Indian Academy of Sciences (India)

    C Grah; on behalf of the FCAL Collaboration

    2007-12-01

    The detectors of the ILC will feature a calorimeter system in the very forward region. The system comprises mainly two electromagnetic calorimeters: LumiCal, which is dedicated to the measurement of the absolute luminosity with highest precision and BeamCal, which uses the energy deposition from beamstrahlung pairs for a fast luminosity measure and the determination of beam parameters. The FCAL system is designed as a universal system fitting all detector concepts. It was implemented and simulated as a subsystem of the large detector concept [1]. The studies are carried out within the FCAL collaboration.

  3. Critical luminosity of compact stars with a strong magnetic field

    International Nuclear Information System (INIS)

    The effect of magnetic field of the neutron star on its gamma bursts is considered. It is shown that the radiative pressure on electrons essentially increases in a strong magnetic field. The comparison of estimates of luminosities of the majority of X ray and gamma sources with critical values of L0 (B) (critical luminosity) shows that one must refuse of traditional views on the conditions of their radiation generation and accept that this process occurs under essentially supercritical conditions because of the increase of the radiative pressure in a strong magnetic field

  4. Jet Luminosity from Neutrino-Dominated Accretion Flows in GRBs

    OpenAIRE

    Kawanaka, Norita

    2013-01-01

    A hyperaccretion disk around a stellar-mass black hole is a plausible model for the central engine that powers gamma-ray bursts (GRBs). We estimate the luminosity of a jet driven by magnetohydrodynamic processes such as the Blandford-Znajek (BZ) mechanism as a function of mass accretion rate, the black hole mass, and other accretion parameters. We show that the jet is most efficient when the accretion flow is cooled via optically-thin neutrino emission, and that its luminosity is much larger ...

  5. Luminosity segregation versus fractal scaling in the galaxy distribution

    OpenAIRE

    Kerscher, Martin

    2003-01-01

    In this letter I present results from a correlation analysis of three galaxy redshift catalogs: the SSRS2, the CfA2 and the PSCz. I will focus on the observation that the amplitude of the two--point correlation function rises if the depth of the sample is increased. There are two competing explanations for this observation, one in terms of a fractal scaling, the other based on luminosity segregation. I will show that there is strong evidence that the observed growth is due to a luminosity dep...

  6. The luminosities of type II Cepheids and RR Lyrae variables

    OpenAIRE

    Feast, Michael

    2009-01-01

    Recent work on the luminosities of type II Cepheids (CephIIs) and RR Lyrae variables is reviewed.In the near infrared (JHKs) the CephIIs in globular clusters show a narrow, linear, period-luminosity relation over their whole period range (about 1 to 100 days). The CephIIs in the general field of the LMC follow this relation for periods shorter than about 20 days. At longer period (the region of the RV Tau stars), the LMC field stars have a significant scatter and in the mean are more luminous...

  7. Development of Silicon Detectors for the High Luminosity LHC

    International Nuclear Information System (INIS)

    The Large Hadron Collider (LHC) at CERN will be upgraded to a High Luminosity LHC in the year 2022, increasing the instantaneous luminosity by a factor of five. This will have major impacts on the experiments at the LHC, such as the Compact Muon Solenoid (CMS) experiment, and especially for their inner silicon tracking systems. Among other things, the silicon sensors used therein will be exposed to unprecedented levels of radiation damage, necessitating a replacement of the entire tracking detector. In order to maintain the excellent current performance, a new tracking detector has to be equipped with sensors of increased radiation hardness and higher granularity. The CMS experiment is undertaking an extensive R and D campaign in the search for the future silicon sensor technology baseline to be used in this upgrade. This thesis presents two methods suitable for use in this search: finite element TCAD simulations and test beam measurements. The simulations are focussed on the interstrip capacitance between sensor strips and are compared to measurements before and after the inclusion of radiation damage effects. A geometrical representation of the strip sensors used in the campaign has been found, establishing the predictive power of simulations. The test beam measurements make use of the high-precision pixel telescopes available at the DESY-II test beam facility. The performance of these telescopes has been assessed and their achievable pointing resolution has been found to be below 2 μm. Thin, epitaxial silicon is a candidate material for usage in radiation hard sensors for the future CMS tracking detector. Sample strip sensors of this material have been irradiated to fluences of up to 1.3 x 1016 neq/cm2 with 800 MeV or 23 GeV protons. Test beam measurements with 5 GeV electrons have been performed to investigate the radiation hardness of epitaxial sensors using the pixel beam telescopes. The epitaxial device under test (DUT) has been integrated into the telescope and its software analysis framework. An alignment of DUT and telescope planes has been performed and traversing particle tracks reconstructed for the sensor analysis. Results show that the achievable resolution in the epitaxial silicon strip sensors is at the binary level. The measured charge collection efficiency for p-bulk sensors amounts to 80% of pre-irradiation levels for fluences of 3 x 1015 neq/cm2 and to over 65% for Φ = 1.3 x 1016 neq/cm2. Signal-to-noise levels at these fluence levels are 7.4 and 3.8, respectively. With particle tracks of various inclinations, the sharing of charge between sensor strips is investigated. Indications of possible charge losses at the sensor surface are described and evidence of commencing charge multiplication effects is presented. Sensors are also compared to thicker, non epitaxial sensors irradiated to the same fluence. From the obtained results, acquired from the first test beam measurements of irradiated epitaxial sensors ever performed, a complete picture of this material has been gained. It can be concluded that thin, p-bulk epitaxial silicon is sufficiently radiation hard for usage as an outer pixel detector sensor material.

  8. Development of Silicon Detectors for the High Luminosity LHC

    Energy Technology Data Exchange (ETDEWEB)

    Eichhorn, Thomas Valentin

    2015-07-15

    The Large Hadron Collider (LHC) at CERN will be upgraded to a High Luminosity LHC in the year 2022, increasing the instantaneous luminosity by a factor of five. This will have major impacts on the experiments at the LHC, such as the Compact Muon Solenoid (CMS) experiment, and especially for their inner silicon tracking systems. Among other things, the silicon sensors used therein will be exposed to unprecedented levels of radiation damage, necessitating a replacement of the entire tracking detector. In order to maintain the excellent current performance, a new tracking detector has to be equipped with sensors of increased radiation hardness and higher granularity. The CMS experiment is undertaking an extensive R and D campaign in the search for the future silicon sensor technology baseline to be used in this upgrade. This thesis presents two methods suitable for use in this search: finite element TCAD simulations and test beam measurements. The simulations are focussed on the interstrip capacitance between sensor strips and are compared to measurements before and after the inclusion of radiation damage effects. A geometrical representation of the strip sensors used in the campaign has been found, establishing the predictive power of simulations. The test beam measurements make use of the high-precision pixel telescopes available at the DESY-II test beam facility. The performance of these telescopes has been assessed and their achievable pointing resolution has been found to be below 2 μm. Thin, epitaxial silicon is a candidate material for usage in radiation hard sensors for the future CMS tracking detector. Sample strip sensors of this material have been irradiated to fluences of up to 1.3 x 10{sup 16} n{sub eq}/cm{sup 2} with 800 MeV or 23 GeV protons. Test beam measurements with 5 GeV electrons have been performed to investigate the radiation hardness of epitaxial sensors using the pixel beam telescopes. The epitaxial device under test (DUT) has been integrated into the telescope and its software analysis framework. An alignment of DUT and telescope planes has been performed and traversing particle tracks reconstructed for the sensor analysis. Results show that the achievable resolution in the epitaxial silicon strip sensors is at the binary level. The measured charge collection efficiency for p-bulk sensors amounts to 80% of pre-irradiation levels for fluences of 3 x 10{sup 15} n{sub eq}/cm{sup 2} and to over 65% for Φ = 1.3 x 10{sup 16} n{sub eq}/cm{sup 2}. Signal-to-noise levels at these fluence levels are 7.4 and 3.8, respectively. With particle tracks of various inclinations, the sharing of charge between sensor strips is investigated. Indications of possible charge losses at the sensor surface are described and evidence of commencing charge multiplication effects is presented. Sensors are also compared to thicker, non epitaxial sensors irradiated to the same fluence. From the obtained results, acquired from the first test beam measurements of irradiated epitaxial sensors ever performed, a complete picture of this material has been gained. It can be concluded that thin, p-bulk epitaxial silicon is sufficiently radiation hard for usage as an outer pixel detector sensor material.

  9. Clustering Segregation With UV Luminosity in Lyman-Break Galaxies at z~3 and Its Implications

    CERN Document Server

    Giavalisco, M; Giavalisco, Mauro; Dickinson, Mark

    2000-01-01

    We report on the clustering properties of Lyman-break galaxies (LBGs) at z~3. The correlation length of flux-limited samples of LBGs depends on their rest-frame ultraviolet (UV) luminosity at lambda ~1700 Angstrom, with fainter galaxies being less strongly clustered in space. It decreases by a factor ~3 over the range of limiting magnitudes that we have probed, namely 25luminosity depends only on how tightly mass and UV luminosity correlate, but is otherwise insensitive to the details of the models. These results provide additional evidence that the strong spatial clustering of LBGs is due to galaxy bi...

  10. Missing baryons traced by the galaxy luminosity density in the large-scale WHIM filaments

    CERN Document Server

    Nevalainen, J; Liivamgi, L J; Branchini, E; Roncarelli, M; Giocoli, C; Heinmki, P; Saar, E; Tamm, A; Finoguenov, A; Nurmi, P; Bonamente, M

    2015-01-01

    We propose a new approach to the missing baryons problem. Building on the common assumption that the missing baryons are in the form of the Warm Hot Intergalactic Medium (WHIM), we further assumed here that the galaxy luminosity density can be used as a tracer of the WHIM. The latter assumption is supported by our finding of a significant correlation between the WHIM density and the galaxy luminosity density in the hydrodynamical simulations of Cui et al. (2012). We further found that the fraction of the gas mass in the WHIM phase is substantially (by a factor of $\\sim$1.6) higher within the large scale galactic filaments, i.e. $\\sim$70\\%, compared to the average in the full simulation volume of $\\sim$0.1\\,Gpc$^3$. The relation between the WHIM overdensity and the galaxy luminosity overdensity within the galactic filaments is consistent with linear: $\\delta_{\\rm whim}\\,=\\,0.7\\,\\pm\\,0.1\\,\\times\\,\\delta_\\mathrm{LD}^{0.9 \\pm 0.2}$. We applied our procedure to the line of sight to the blazar H2356-309 and found e...

  11. Simulation Studies for a new ATLAS Inner Detector for the High-Luminosity LHC

    CERN Document Server

    Styles, N; The ATLAS collaboration

    2012-01-01

    To maintain scientific progress, the LHC will require a major upgrade after 2020. The current plans include increasing the instantaneous luminosity by a factor of 5 (utilising luminosity levelling) beyond the original design value. This project is referred to as the HL-LHC (High Luminosity LHC), and its aim is to provide 3000 fb^{-1} of sqrt(s)=14 TeV proton-proton collisions in 10 to 12 years. The HL-LHC will be an extremely challenging experimental environment, with significantly higher particle fluxes, radiation doses and detector occupancies than experienced currently by the LHC experiments. The present ATLAS Inner Detector (ID) will not be suitable for operation in such conditions and will be completely replaced by a new, all-silicon Inner Tracker (ITk). The ITk must satisfy the following criteria, with respect to the current ID, in order to achieve the desired levels of physics performance: higher granularity, improved material budget and increased radiation hardness of the readout components. Currently...

  12. The rest-frame optical luminosity functions of galaxies at 2

    CERN Document Server

    Marchesini, D; Quadri, R; Rudnick, G; Franx, M; Lira, P; Wuyts, S; Gawiser, E; Christlein, D; Toft, S; Marchesini, Danilo; Dokkum, Pieter van; Quadri, Ryan; Rudnick, Gregory; Franx, Marijn; Lira, Paulina; Wuyts, Stijn; Gawiser, Eric; Christlein, Daniel; Toft, Sune

    2006-01-01

    [ABRIDGED] We present the rest-frame optical (B, V, and R-band) luminosity functions (LFs) of galaxies at 22 are consistent with those in the local LFs. The characteristic magnitudes are significantly brighter than the local values, while the measured values for Phi_star are a factor of ~5 smaller with respect to the local values. By integrating the LFs, we estimate the number and luminosity densities. We present for the first time the LF of Distant Red Galaxies (DRGs; defined here as z>2 sources with observed J-K>2.3). While DRGs and non-DRGs are characterized by similar LFs at the bright end, the faint-end slope of the non-DRG LF is much steeper than that of DRGs. Comparing the rest-frame V-band LF of non-DRGs to that inferred for Lyman break galaxies by Shapley et al. (2001), we find a significantly less steep faint-end slope. The contribution of DRGs to the global densities is 14%-25% in number and 22%-33% in luminosity. From the rest-frame U-V colors and stellar population synthesis models, we estimate t...

  13. The Dependence of Type Ia Supernova Luminosities on their Host Galaxies

    CERN Document Server

    Sullivan, M; Howell, D A; Neill, J D; Astier, P; Balland, C; Basa, S; Carlberg, R G; Fouchez, D; Guy, J; Hardin, D; Hook, I M; Pain, R; Palanque-Delabrouille, N; Perrett, K M; Pritchet, C J; Regnault, N; Rich, J; Ruhlmann-Kleider, V; Baumont, S; Hsiao, E; Kronborg, T; Lidman, C; Perlmutter, S; Walker, E S

    2010-01-01

    (Abridged) Precision cosmology with Type Ia supernovae (SNe Ia) makes use of the fact that SN Ia luminosities depend on their light-curve shapes and colours. Using Supernova Legacy Survey (SNLS) and other data, we show that there is an additional dependence on the global characteristics of their host galaxies: events of the same light-curve shape and colour are, on average, 0.08mag (~4.0sigma) brighter in massive host galaxies (presumably metal-rich) and galaxies with low specific star-formation rates (sSFR). SNe Ia in galaxies with a low sSFR also have a smaller slope ("beta") between their luminosities and colours with ~2.7sigma significance, and a smaller scatter on SN Ia Hubble diagrams (at 95% confidence), though the significance of these effects is dependent on the reddest SNe. SN Ia colours are similar between low-mass and high-mass hosts, leading us to interpret their luminosity differences as an intrinsic property of the SNe and not of some external factor such as dust. If the host stellar mass is in...

  14. Studies of Read-Out Electronics and Trigger for Muon Drift Tube Detectors at High Luminosities

    CERN Document Server

    Nowak, Sebastian

    The Large Hadron Collider (LHC) at the European Centre for Particle Physics, CERN, collides protons with an unprecedentedly high centre-of-mass energy and luminosity. The collision products are recorded and analysed by four big experiments, one of which is the ATLAS detector. For precise measurements of the properties of the Higgs-Boson and searches for new phenomena beyond the Standard Model, the LHC luminosity of $L=10^{34}cm^{-2}s^{-1}$ is planned to be increased by a factor of ten leading to the High Luminosity LHC (HL-LHC). In order to cope with the higher background and data rates, the LHC experiments need to be upgraded. In this thesis, studies for the upgrade of the ATLAS Muon Spectrometer are presented with respect to the read-out electronics of the Monitored Drift Tube (MDT) and the small-diameter Muon Drift Tube (sMDT) chambers and the Level-1 muon trigger. Due to the reduced tube diameter of sMDT chambers, background occupancy and space charge effects are suppressed by an order of magnitude compar...

  15. Truncation of the Inner Accretion Disk Around a Black Hole at Low Luminosity

    Science.gov (United States)

    Tomsick, John A.; Yamoka, Kazutaka; Corbel, Stephane; Kaaret, Philip; Kalemci, Emrah; Migliari, Simone

    2011-01-01

    Most black hole binaries show large changes in X-ray luminosity caused primarily by variations in mass accretion rate. An important question for understanding black hole accretion and jet production is whether the inner edge of the accretion disk recedes at low accretion rate. Measurements of the location of the inner edge (R(sub in)) can be made using iron emission lines that arise due to fluorescence of iron in the disk, and these indicate that R(sub in) is very close to the black hole at high and moderate luminosities (greater than or equal to 1% of the Eddington luminosity, L(sub Edd). Here, we report on X-ray observations of the black hole GX 339-4 in the hard state by Suzaku and the Rossi X-ray Timing Explorer that extend iron line studies to 0.14% L(sub Edd) and show that R(sub in) increases by a factor of greater than 27 over the value found when GX 339-4 was bright. The exact value of R(sub in) depends on the inclination of the inner disk (i), and we derive 90% confidence limits of R(sub in) greater than 35 R(sub g) at i = 0 degrees and R(sub in) greater than 175 R(sub g) at i = 30 degrees. This provides direct evidence that the inner portion of the disk is not present at low luminosity, allowing for the possibility that the inner disk is replaced by advection- or magnetically dominated accretion flows.

  16. Connections between the Radio, Optical and Soft X-ray Luminosities for Flat-Spectrum Radio Quasars

    Indian Academy of Sciences (India)

    Zhi-Fu Chen; Cai-Juan Pan; You-Bing Li; Yu-Tao Zhou

    2014-09-01

    We investigate the connections between radio, optical and soft X-ray luminosities with a sample of 538 FSRQs. We find that the radio luminosity is strongly correlated with the optical luminosity, as well as with the soft X-ray luminosity. We also find that the optical luminosity is strongly correlated with the soft X-ray luminosity.

  17. The Radius-Luminosity Relationship for Active Galactic Nuclei

    DEFF Research Database (Denmark)

    Bentz, Misty C.; Peterson, Bradley M.; Netzer, Hagai; Pogge, Richard W.; Vestergaard, Marianne

    2009-01-01

    We present high-resolution HST images of all 35 AGNs with optical reverberation-mapping results, which we have modeled to create a nucleus-free image of each AGN host galaxy. From the nucleus-free images, we determine the host-galaxy contribution to ground-based spectroscopic luminosity measureme...

  18. Cosmic downsizing of powerful radio galaxies to low radio luminosities

    CERN Document Server

    Rigby, E E; Best, P N; Rosario, D; Röttgering, H J A

    2015-01-01

    At bright radio powers ($P_{\\rm 1.4 GHz} > 10^{25}$ W/Hz) the space density of the most powerful sources peaks at higher redshift than that of their weaker counterparts. This paper establishes whether this luminosity-dependent evolution persists for sources an order of magnitude fainter than those previously studied, by measuring the steep--spectrum radio luminosity function (RLF) across the range $10^{24} 10^{26}$ W/Hz the redshift of the peak space density increases with luminosity, whilst at lower radio luminosities the position of the peak remains constant within the uncertainties. This `cosmic downsizing' behaviour is found to be similar to that seen at optical wavelengths for quasars, and is interpreted as representing the transition from radiatively efficient to inefficient accretion modes in the steep-spectrum population. This conclusion is supported by constructing simple models for the space density evolution of these two different radio galaxy classes; these are able to successfully reproduce the ...

  19. LHC Report: Boost in bunches brings record luminosity

    CERN Multimedia

    2011-01-01

    Having hit a luminosity of around 8.4x1032 cm-2 s-1 with 768 bunches per beam, the LHC went into a 5-day machine development (MD) program on Wednesday 4 May. Operators are now working on increasing the number of particle bunches in the machine towards a 2011 maximum of around 1380 bunches. The team is already hitting major milestones, recording another record-breaking peak luminosity on Monday 23 May.   Former LHC Project Leader Lyn Evans (to the right) and Laurette Ponce, the engineer-in-charge when the recent luminosity record was achieved. The MD periods improve our understanding of the machine, with the aim of increasing its short- and long-term performance. This one also included tests of the machine’s configurations for special physics runs and a future high luminosity LHC. It was an intense program and overall it went very well, with most measurements carried out successfully. Highlights included: commissioning a dedicated machine setup for TOTEM and ALFA; succe...

  20. Finding and characterising WHIM structures using the luminosity density method

    CERN Document Server

    Nevalainen, J; Tempel, E; Branchini, E; Roncarelli, M; Giocoli, C; Heinamaki, P; Saar, E; Bonamente, M; Einasto, M; Finoguenov, A; Kaastra, J; Lindfors, E; Nurmi, P; Ueda, Y

    2014-01-01

    We have developed a new method to approach the missing baryons problem. We assume that the missing baryons reside in a form of Warm Hot Intergalactic Medium, i.e. the WHIM. Our method consists of (a) detecting the coherent large scale structure in the spatial distribution of galaxies that traces the Cosmic Web and that in hydrodynamical simulations is associated to the WHIM, (b) map its luminosity into a galaxy luminosity density field, (c) use numerical simulations to relate the luminosity density to the density of the WHIM, (d) apply this relation to real data to trace the WHIM using the observed galaxy luminosities in the Sloan Digital Sky Survey and 2dF redshift surveys. In our application we find evidence for the WHIM along the line of sight to the Sculptor Wall, at redshifts consistent with the recently reported X-ray absorption line detections. Our indirect WHIM detection technique complements the standard method based on the detection of characteristic X-ray absorption lines, showing that the galaxy l...

  1. Upgraded Fast Beam Conditions Monitor for CMS online luminosity measurement

    CERN Document Server

    Leonard, Jessica Lynn

    2014-01-01

    The CMS beam and radiation monitoring subsystem BCM1F during LHC Run I consisted of 8 individual diamond sensors situated around the beam pipe within the tracker detector volume, for the purpose of fast monitoring of beam background and collision products. Effort is ongoing to develop the use of BCM1F as an online bunch-by-bunch luminosity monitor. BCM1F will be running whenever there is beam in LHC, and its data acquisition is independent from the data acquisition of the CMS detector, hence it delivers luminosity even when CMS is not taking data. To prepare for the expected increase in the LHC luminosity and the change from 50 ns to 25 ns bunch separation, several changes to the system are required, including a higher number of sensors and upgraded electronics. In particular, a new real-time digitizer with large memory was developed and is being integrated into a multi-subsystem framework for luminosity measurement. Current results from Run II preparation will be shown, including results from the January 201...

  2. ESTIMATING THE PROMPT ELECTROMAGNETIC LUMINOSITY OF A BLACK HOLE MERGER

    International Nuclear Information System (INIS)

    Although recent work in numerical relativity has made tremendous strides in quantifying the gravitational wave luminosity of black hole mergers, very little is known about the electromagnetic luminosity that might occur in immediate conjunction with these events. We show that whenever the heat deposited in the gas near a pair of merging black holes is proportional to its total mass, and the surface density of the gas in the immediate vicinity is greater than the (quite small) amount necessary to make it optically thick, the characteristic scale of the luminosity emitted in direct association with the merger is the Eddington luminosity independent of the gas mass. The duration of the photon signal is proportional to the gas mass, and is generally rather longer than the merger event. At somewhat larger distances, dissipation associated with realigning the gas orbits to the new spin orientation of the black hole can supplement dissipation of the energy gained from orbital adjustment to the mass lost in gravitational radiation; these two heat sources can combine to augment the electromagnetic radiation over longer timescales.

  3. Attaining high luminosity in linear e+e- colliders

    International Nuclear Information System (INIS)

    The attainment of high luminosity in linear colliders is a complex problem because of the interdependence of the critical parameters. For instance, changing the number of particles per bunch affects the damping ring design and thus the emittance; it affects the wakefields in the linac and thus the momentum spread; the momentum spread affects the final focus design and thus the final β*; but the emittance change also affects the final focus design; and all these come together to determine the luminosity, disruption and beamstrahlung at the intersection. Changing the bunch length, or almost any other parameter, has a similar chain reaction. Dealing with this problem by simple scaling laws is very difficult because one does not know which parameter is going to be critical, and thus which should be held constant. One can only maximize the luminosity by a process of search and iteration. The process can be facilitated with the aid of a computer program. Examples can then be optimized for maximum luminosity, and compared to the optimized solutions with different approaches. This paper discusses these approaches

  4. Cosmic Evolution of Long Gamma-Ray Burst Luminosity

    CERN Document Server

    Deng, Can-Min; Guo, Bei-Bei; Lu, Rui-Jing; Wang, Yuan-Zhu; Wei, Jun-Jie; Wu, Xue-Feng; Liang, En-Wei

    2016-01-01

    The cosmic evolution of gamma-ray burst (GRB) luminosity is essential for revealing the GRB physics and for using GRBs as cosmological probes. We investigate the luminosity evolution of long GRBs with a large sample of 258 {\\em Swift}/BAT GRBs. Parameterized the peak luminosity of individual GRBs evolves as $L_{\\rm p}\\propto{\\rm }(1+z)^{k}$, we get $k=1.49\\pm0.19$ using the non-parametric $\\tau$ statistics method without considering observational biases of GRB trigger and redshift measurement. By modeling these biases with the observed peak flux and characterizing the peak luminosity function of long GRBs as a smoothly broken power-law with a break that evolves as $L_{\\rm b}\\propto (1+z)^{k_{\\rm b}}$, we obtain $k_{\\rm b}=1.14^{+0.99}_{-0.47}$ through simulations based on assumption that the long GRB rate follows the star formation rate (SFR) incorporating with cosmic metallicity history. The derived $k$ and $k_b$ values are systematically smaller than that reported in previous papers. By removing the observa...

  5. The Radius-Luminosity Relationship for Active Galactic Nuclei

    DEFF Research Database (Denmark)

    Bentz, Misty C.; Peterson, Bradley M.; Pogge, Richard W.; Vestergaard, Marianne; Onken, Christopher A.

    2006-01-01

    We have obtained high resolution images of the central regions of 14 reverberation-mapped active galactic nuclei (AGN) using the Hubble Space Telescope Advanced Camera for Surveys High Resolution Camera to account for host-galaxy starlight contamination of measured AGN luminosities. We measure the...

  6. TOTAL INFRARED LUMINOSITY ESTIMATION OF RESOLVED AND UNRESOLVED GALAXIES

    International Nuclear Information System (INIS)

    The total infrared (TIR) luminosity from galaxies can be used to examine both star formation and dust physics. We provide here new relations to estimate the TIR luminosity from various Spitzer bands, in particular from the 8 ?m and 24 ?m bands. To do so, we use data for 45'' subregions within a subsample of nearby face-on spiral galaxies from the Spitzer Infrared Nearby Galaxies Survey (SINGS) that have known oxygen abundances as well as integrated galaxy data from the SINGS, the Local Volume Legacy survey (LVL), and Engelbracht et al. samples. Taking into account the oxygen abundances of the subregions, the star formation rate intensity, and the relative emission of the polycyclic aromatic hydrocarbons at 8 ?m, the warm dust at 24 ?m, and the cold dust at 70 ?m and 160 ?m, we derive new relations to estimate the TIR luminosity from just one or two of the Spitzer bands. We also show that the metallicity and the star formation intensity must be taken into account when estimating the TIR luminosity from two wave bands, especially when data longward of 24 ?m are not available.

  7. Upgraded Fast Beam Conditions Monitor for CMS online luminosity measurement

    CERN Document Server

    Leonard, Jessica Lynn; Hempel, Maria; Henschel, Hans; Karacheban, Olena; Lange, Wolfgang; Lohmann, Wolfgang; Novgorodova, Olga; Penno, Marek; Walsh, Roberval; Dabrowski, Anne; Guthoff, Moritz; Loos, R; Ryjov, Vladimir; Burtowy, Piotr; Lokhovitskiy, Arkady; Odell, Nathaniel; Przyborowski, Dominik; Stickland, David P; Zagozdzinska, Agnieszka

    2014-01-01

    The CMS beam condition monitoring subsystem BCM1F during LHC Run I consisted of 8 individual diamond sensors situated around the beam pipe within the tracker detector volume, for the purpose of fast monitoring of beam background and collision products. Effort is ongoing to develop the use of BCM1F as an online bunch-by-bunch luminosity monitor. BCM1F will be running whenever there is beam in LHC, and its data acquisition is independent from the data acquisition of the CMS detector, hence it delivers luminosity even when CMS is not taking data. To prepare for the expected increase in the LHC luminosity and the change from 50 ns to 25 ns bunch separation, several changes to the system are required, including a higher number of sensors and upgraded electronics. In particular, a new real-time digitizer with large memory was developed and is being integrated into a multi-subsystem framework for luminosity measurement. Current results from Run II preparation will be discussed, including results from the January 201...

  8. PANDA luminosity detector software: preparation for expected challenges

    International Nuclear Information System (INIS)

    Precise determination of the luminosity is crucial for planned PANDA experiment (FAIR, Germany). For the luminosity measurement we will exploit the differential cross section of the elastic pp scattering in dependence of the scattering angle. The Luminosity Detector (LMD) should have full azimuthal angle acceptance and good spatial resolution to achieve the needed precision for the measurement. These requirements can be succeeded by four planes of thin silicon pixel sensors. In parallel to the prototype construction, the reconstruction software is under development. Monte Carlo based simulation is used to proof the design concept, test the reconstruction under different conditions and study expected distortions of the simulated ideal world by real life effects. Those effects include possible technical problems (e.g. sensor misalignment or broken sensors) as well as challenges not related directly to the LMD set-up (e.g. physical background or radiation damage). Moreover the extraction of the luminosity relies on a sophisticated fit to the data with a combination of the theory model, non-uniform detector resolution and reconstruction efficiency. A special framework was developed to simplify fitting procedure.

  9. The Nuclear Infrared Emission of Low-Luminosity AGN

    CERN Document Server

    Mason, R E; Packham, C; Alonso-Herrero, A; Levenson, N A; Radomski, J; Almeida, C Ramos; Colina, L; Elitzur, M; Aretxaga, I; Roche, P F; Oi, N

    2012-01-01

    We have obtained high-resolution mid-infrared (MIR) imaging, nuclear spectral energy distributions (SEDs) and archival Spitzer spectra for 22 low-luminosity active galactic nuclei (LLAGN; L_bol < 5 x 10^42 erg/s). Infrared (IR) observations may advance our understanding of the accretion flows in LLAGN, the fate of the obscuring torus at low accretion rates, and, perhaps, the star formation histories of these objects. However, while comprehensively studied in higher-luminosity Seyferts and quasars, the nuclear IR properties of LLAGN have not yet been well-determined. In these proceedings we summarise the results for the LLAGN at the relatively high-luminosity, high-Eddington ratio end of the sample. Strong, compact nuclear sources are visible in the MIR images of these objects, with luminosities consistent with or slightly in execss of that predicted by the standard MIR/X-ray relation. Their broadband nuclear SEDs are diverse; some resemble typical Seyfert nuclei, while others possess less of a well-defined...

  10. A high luminosity spectrometer for deep inelastic muon scattering experiments

    International Nuclear Information System (INIS)

    A 50 m long magnetized iron torus enclosing a 40 m long target provides the luminosity and acceptance necessary for the study of deep inelastic muon scattering at high Q2. The construction and performance of this spectrometer and the associated trigger are described. Details of the data acquisition system and data analysis are also given. (orig.)

  11. A Single Bremsstrahlung Monitor to Measure Luminosity at LEP

    CERN Multimedia

    2002-01-01

    The luminosity, the beam divergence and the longitudinal polarization can be measured at an interaction point of LEP by dectecting the energy, the angular distribution and the circular polarization of the single bremsstrahlung photons (SB) emitted at very forward angle. The luminosity can be measured by this met than by the conventional method of detecting small angle Bhabha scattering. The bunch to bunch relative luminosity can be monitored at a few per mil level in few minutes. Absolute values of the luminosity and of the polarization can be measured with a precision of the order of 1\\%. \\\\ \\\\ The apparatus to detect SB photons consists of a low Z absorber and of an EM calorimeter made of lead and scintillating fibres. Both the total energy and the space distribution of the SB photons are measured. This apparatus has been designed and built at the Department of Physics and INFN Section of the University of Rome ``La Sapienza''. Later on, together with suitable monocrystal converters, it may be used also for...

  12. A new record peak luminosity for the LHC

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    Two weeks of dedicated machine development paid off last weekend when the LHC ran for physics with three nominal intensity (∼1011 protons) bunches in each beam.   This brought a new record peak luminosity of around 8×1029 cm-2 s-1, and allowed the LHC to double the integrated luminosity delivered to the experiments since 30 March from 16 to 32 inverse nanobarns over the weekend. After a few more fills in this configuration, the number of bunches will be raised to six per beam, which will in turn allow the peak luminosity to break the 1030 cm-2 s-1 barrier for the first time, well on the way to achieving the 2010 objective of 1032 cm-2 s-1. This peak luminosity goal requires 800 nominal bunches per beam squeezed to a beta of 3.5 metres. The plan for 2011 is to run the LHC in this configuration over about 10 months, thus achieving the objective of recording one inverse femtobarn of data in total. The machine development period also allowed the TOTEM detectors to be set up with 45...

  13. Direct Oxygen Abundances for Low Luminosity LVL Galaxies

    CERN Document Server

    Berg, Danielle A; Marble, Andrew R; van Zee, Liese; Engelbracht, Charles W; Lee, Janice C; Kennicutt, Robert C; Jr.,; Calzetti, Daniela; Dale, Daniel A; Johnson, Benjamin D

    2012-01-01

    We present MMT spectroscopic observations of HII regions in 42 low luminosity galaxies in the LVL. For 31 galaxies, we measured the temperature sensitive [O III] line at a strength of 4 sigma or greater, and thus determine direct oxygen abundances. Our results provide the first direct estimates of oxygen abundance for 19 galaxies. Oxygen abundances were compared to B-band and 4.5 micron luminosities and stellar masses in order to characterize the luminosity-metallicity (L-Z) and mass-metallicity (M-Z) relationships at low-luminosity. We present and analyze a "Combined Select" sample composed of 38 objects (drawn from our parent sample and the literature) with direct oxygen abundances and reliable distance determinations (TRGB or Ceph). Consistent with previous studies, the B-band and 4.5 micron L-Z relationships were found to be 12+log(O/H)=(6.27+/-0.21)+(-0.11+/-0.01)M_B and 12+log(O/H)=(6.10+/-0.21)+(-0.10+/-0.01)M_[4.5] (sigma=0.15 and 0.14). For this sample, we derive a M-Z relationship of 12+log(O/H)=(5....

  14. Performance of New and Upgraded Detectors for Luminosity and Beam Condition Measurement at CMS

    OpenAIRE

    Leonard, Jessica Lynn

    2015-01-01

    The beam monitoring and luminosity systems of the CMS experiment are enhanced by several new and upgraded sub-detectors to match the challenges of the LHC operation and physics program at increased energy and higher luminosity. A dedicated pixelated luminosity telescope is installed for a fast and precise luminosity measurement. This detector measures coincidences between several three-layer telescopes of silicon pixel detectors to arrive at luminosity for each colliding LHC bunch pair. An up...

  15. Precision luminosity measurement at LHCb with beam-gas imaging

    Energy Technology Data Exchange (ETDEWEB)

    Barschel, Colin

    2014-03-05

    The luminosity is the physical quantity which relates the cross-section to the production rate in collider experiments. The cross-section being the particle physics observable of interest, a precise determination of the luminosity is required. This work presents the absolute luminosity calibration results performed at the Large Hadron Collider beauty (LHCb) experiment at CERN using a novel method based on beam-gas interactions with data acquired at a center of mass energy √(s)=8 TeV and √(s)=2.76 TeV. Reconstructed beam-gas interaction vertices in LHCb are used to measure the beam profiles, thus making it possible to determine the beams overlap integral. An important element of this work was to install and use a neon gas injection system to increase the beam-gas interaction rate. The precision reached with the beam-gas imaging method relies on the two-dimensional beam shape determination developed in this work. For such precision, the interaction vertex resolution is an important ingredient. Therefore, a new method has been developed using all reconstructed vertices in order to improve the understanding of the vertex resolution. In addition to the overlap integral, the knowledge of the colliding bunch populations is required to measure the luminosity. The determination of the bunch populations relies on LHC instruments to measure the bunch population fractions and the total beam intensity. Studies performed as part of this work resulted in a reduction of the bunch current normalization uncertainty from ±2.7% to ±0.2% and making it possible to achieve precision luminosity measurements at all LHC experiments. Furthermore, information on beam-gas interactions not originating from nominally filled bunches was analyzed to determine the charge fraction not participating in bunch collisions. The knowledge of this fraction is required to correct the total beam intensity. The reference cross-section of pp interactions with at least two tracks in the vertex detector was measured with the beam-gas imaging method. The result is σ{sub Track}=60.6±0.9 mb at a center-of-mass energy of √(s)=8 TeV. The same measurement performed at √(s)=2.76 TeV results in a cross-section of σ{sub Track}=52.7±1.2 mb. The luminosity measurement at √(s)=8 TeV presented here, with an uncertainty of 1.4%, is to date the most precise luminosity calibration performed at the LHC and at any other bunched-beam proton collider.

  16. Determination of the absolute luminosity at the LHC

    International Nuclear Information System (INIS)

    The work presented in this thesis significantly contributed to LHC (Large Hadron Collider) start-up. A first luminosity calibration using the Van Der Meer scan method was provided to the particle physics experiments. The anticipated sources of uncertainty were estimated by simulations and analytical approach Measurements confirmed that most of them were small and could be well determined. The main contribution to the overall uncertainty comes from the knowledge of the beam intensities. A resolution of 11% was reached at the very first try. The first observations and a detailed study and characterization of systematic uncertainties indicate that under well controlled and optimized beam conditions a precision of 5% could be reached in future absolute luminosity measurements. Chapter 1 of this thesis is intended as an introduction to general accelerators physics concepts and definitions that will be used in the following chapters. General expressions of the luminosity are derived including complications such as the presence of a crossing angle or the hourglass effect. Chapter 2 focuses on the Van Der Meer method. The principle of the method and implications of the effects introduced in Chapter 1 are discussed. Chapter 3 and 4 give an overview of the CERN accelerator complex focusing on the LHC and its instrumentation. Beam dynamics and optics studies related to the optimization of the collisions and more generally of the interaction regions are shown as well as tracking simulations for the LHC luminosity monitors. Chapter 5 and 6 present the results obtained at the LHC and RHIC during luminosity calibration measurements. A detailed analysis of the systematics uncertainties associated to the measurement and proposals for future improvements are discussed. Chapter 6 also describes more specifically the procedure and implementation of the tools for luminosity optimization and calibration at the LHC as well as the first experience with operation in collision. Finally, in Chapter 7, an alternative method for luminosity calibration is introduced. Dedicated optics are required for this measurement. An overview of the study and performance of these optics is presented

  17. Precision luminosity measurement at LHCb with beam-gas imaging

    International Nuclear Information System (INIS)

    The luminosity is the physical quantity which relates the cross-section to the production rate in collider experiments. The cross-section being the particle physics observable of interest, a precise determination of the luminosity is required. This work presents the absolute luminosity calibration results performed at the Large Hadron Collider beauty (LHCb) experiment at CERN using a novel method based on beam-gas interactions with data acquired at a center of mass energy √(s)=8 TeV and √(s)=2.76 TeV. Reconstructed beam-gas interaction vertices in LHCb are used to measure the beam profiles, thus making it possible to determine the beams overlap integral. An important element of this work was to install and use a neon gas injection system to increase the beam-gas interaction rate. The precision reached with the beam-gas imaging method relies on the two-dimensional beam shape determination developed in this work. For such precision, the interaction vertex resolution is an important ingredient. Therefore, a new method has been developed using all reconstructed vertices in order to improve the understanding of the vertex resolution. In addition to the overlap integral, the knowledge of the colliding bunch populations is required to measure the luminosity. The determination of the bunch populations relies on LHC instruments to measure the bunch population fractions and the total beam intensity. Studies performed as part of this work resulted in a reduction of the bunch current normalization uncertainty from ±2.7% to ±0.2% and making it possible to achieve precision luminosity measurements at all LHC experiments. Furthermore, information on beam-gas interactions not originating from nominally filled bunches was analyzed to determine the charge fraction not participating in bunch collisions. The knowledge of this fraction is required to correct the total beam intensity. The reference cross-section of pp interactions with at least two tracks in the vertex detector was measured with the beam-gas imaging method. The result is σTrack=60.6±0.9 mb at a center-of-mass energy of √(s)=8 TeV. The same measurement performed at √(s)=2.76 TeV results in a cross-section of σTrack=52.7±1.2 mb. The luminosity measurement at √(s)=8 TeV presented here, with an uncertainty of 1.4%, is to date the most precise luminosity calibration performed at the LHC and at any other bunched-beam proton collider.

  18. DIRECT OXYGEN ABUNDANCES FOR LOW-LUMINOSITY LVL GALAXIES

    International Nuclear Information System (INIS)

    We present MMT spectroscopic observations of H II regions in 42 low luminosity galaxies in the Spitzer Local Volume Legacy survey. For 31 of the 42 galaxies in our sample, we were able to measure the temperature sensitive [O III] λ4363 line at a strength of 4σ or greater, and thus determine oxygen abundances using the 'direct' method. Our results provide the first 'direct' estimates of oxygen abundance for 19 of these galaxies. 'Direct' oxygen abundances were compared to B-band luminosities, 4.5 μm luminosities, and stellar masses in order to characterize the luminosity-metallicity and mass-metallicity relationships at low luminosity. We present and analyze a 'Combined Select' sample composed of 38 objects (drawn from a sub-set of our parent sample and the literature) with 'direct' oxygen abundances and reliable distance determinations (based on the tip of the red giant branch or Cepheid variables). Consistent with previous studies, the B band and 4.5 μm luminosity-metallicity relationships for the 38 objects were found to be 12 + log(O/H) = (6.27 ± 0.21) + (– 0.11 ± 0.01)MB and 12 + log(O/H) = (6.10 ± 0.21) + (– 0.10 ± 0.01)M[4.5] with dispersions of σ = 0.15 and 0.14, respectively. The slopes of the optical and near-IR L-Z relationships have been reported to be different for galaxies with luminosities greater than that of the LMC. However, the similarity of the slopes of the optical and near-IR L-Z relationships for our sample probably reflects little influence by dust extinction in the low luminosity galaxies. For this sample, we derive a mass-metallicity relationship of 12 + log(O/H) = (5.61 ± 0.24) + (0.29 ± 0.03)log (M*), which agrees with previous studies; however, the dispersion (σ = 0.15) is not significantly lower than that of the L-Z relationships. Because of the low dispersions in these relationships, if an accurate distance is available, the luminosity of a low luminosity galaxy is often a better indicator of metallicity than that derived using certain 'strong-line' methods, so significant departures from the L-Z relationships may indicate that caution is prudent in such cases. With these new 'direct' metallicities we also revisit the 70/160 μm color metallicity relationship. Additionally, we examine N/O abundance trends with respect to oxygen abundance and B – V color. We find a positive correlation between N/O ratio and B – V color for 0.05 ∼< B – V ∼< 0.75: log (N/O) = (1.18 ± 0.9) × (B – V) + (– 1.92 ± 0.08), with a dispersion of σ = 0.14, which is in agreement with previous studies.

  19. Cosmic Evolution of Long Gamma-Ray Burst Luminosity

    Science.gov (United States)

    Deng, Can-Min; Wang, Xiang-Gao; Guo, Bei-Bei; Lu, Rui-Jing; Wang, Yuan-Zhu; Wei, Jun-Jie; Wu, Xue-Feng; Liang, En-Wei

    2016-03-01

    The cosmic evolution of gamma-ray burst (GRB) luminosity is essential for revealing the GRB physics and for using GRBs as cosmological probes. We investigate the luminosity evolution of long GRBs with a large sample of 258 Swift/BAT GRBs. By describing the peak luminosity evolution of individual GRBs as {L}{{p}}\\propto \\text{}{(1+z)}k, we get k=1.49+/- 0.19 using the nonparametric τ statistics method without considering observational biases of GRB trigger and redshift measurement. By modeling these biases with the observed peak flux and characterizing the peak luminosity function of long GRBs as a smoothly broken power law with a break that evolves as {L}{{b}}\\propto {(1+z)}{k{{b}}}, we obtain {k}{{b}}={1.14}-0.47+0.99 through simulations based on the assumption that the long GRB rate follows the star formation rate incorporating the cosmic metallicity history. The derived k and kb values are systematically smaller than those reported in previous papers. By removing the observational biases of the GRB trigger and redshift measurement based on our simulation analysis, we generate mock complete samples of 258 and 1000 GRBs to examine how these biases affect the τ statistics method. We get k=0.94+/- 0.14 and k=0.80+/- 0.09 for the two samples, indicating that these observational biases may lead to overestimating the k value. With the large uncertainty of kb derived from our simulation analysis, one cannot even convincingly argue for a robust evolution feature of the GRB luminosity.

  20. DISK GALAXIES WITH BROKEN LUMINOSITY PROFILES FROM COSMOLOGICAL SIMULATIONS

    International Nuclear Information System (INIS)

    We present smoothed particle hydrodynamics cosmological simulations of the formation of three disk galaxies with a detailed treatment of chemical evolution and cooling. The resulting galaxies have properties compatible with observations: relatively high disk-to-total ratios, thin stellar disks, and good agreement with the Tully-Fisher and the luminosity-size relations. They present a break in the luminosity profile at 3.0 0.5 disk scale lengths while showing an exponential mass profile without any apparent breaks, which is in line with recent observational results. Since the stellar mass profile is exponential, only differences in the stellar populations can be the cause of the luminosity break. Although we find a cutoff for the star formation rate (SFR) imposed by a density threshold in our star formation model, it does not coincide with the luminosity break and is located at 4.3 0.4 disk scale lengths, with star formation going on between both radii. The color profiles and the age profiles are 'U-shaped', with the minimum for both profiles located approximately at the break radius. The SFR to stellar mass ratio increases until the break, explaining the coincidence of the break with the minimum of the age profile. Beyond the break, we find a steep decline in the gas density and, consequently, a decline in the SFR and redder colors. We show that most stars (64%-78%) in the outer disk originate in the inner disk and afterward migrate there. Such stellar migrations are likely the main origin of the U-shaped age profile and, therefore, of the luminosity break.

  1. Research and Development for a Free-Running Readout System for the ATLAS LAr Calorimeters at the High Luminosity LHC

    CERN Document Server

    Hils, Maximilian; The ATLAS collaboration

    2015-01-01

    The ATLAS Liquid Argon (LAr) Calorimeters were designed and built to measure electromagnetic and hadronic energy in proton-proton collisions produced at the LHC at centre-of-mass energies up to 14 TeV and instantaneous luminosities up to $10^{34} \\text{cm}^{-2} \\text{s}^{-1}$. The High Luminosity LHC (HL-LHC) programme is now developed for up to 5-7 times the design luminosity, with the goal of accumulating an integrated luminosity of $3000~\\text{fb}^{-1}$. In the HL-LHC phase, the increased radiation levels require a replacement of the front-end electronics of the LAr Calorimeters. Furthermore, the ATLAS trigger system is foreseen to increase the trigger accept rate by a factor 10 to 1 MHz and the trigger latency by a factor of 20 which requires a larger data volume to be buffered. Therefore, the LAr Calorimeter read-out will be exchanged with a new front-end and a high bandwidth back-end system for receiving data from all 186.000 channels at 40 MHz LHC bunch-crossing frequency and for off-detector buffering...

  2. Hydrostatic equilibrium of a porous intracluster medium: implications for mass fraction and X-ray luminosity

    CERN Document Server

    Nusser, Adi

    2007-01-01

    The presence of dilute hot cavities in the intracluster medium (ICM) at the cores of clusters of galaxies changes the relation between gas temperature and its X-ray emission properties. Using the hydrostatic equations of a porous medium we solve for the ICM density for a given temperature as a function of the filling factor of dilute bubbles. We find that at a given temperature, the core X-ray luminosity increases with the filling factor. If the frequency of AGNs in clusters were higher in the past, then the filling factor is correspondingly affected, with implications for the cluster scaling relations. This is especially important for the core properties, including the temperature-luminosity ($L_X-T$) relation and estimates of the core gas mass. The results imply an epoch-dependent sensitivity of the $L_X-T$ relation in the core to the porosity of the ICM. Detection of such an effect would give new insights into AGN feedback.

  3. Direct Oxygen Abundances for the Lowest Luminosity LVL Galaxies

    Science.gov (United States)

    Berg, Danielle; Skillman, E. D.; Marble, A. R.; van Zee, L.; Engelbracht, C. W.

    2012-01-01

    We present new MMT spectroscopic observations of HII regions in 42 of the lowest luminosity galaxies in the Spitzer Local Volume Legacy (LVL) survey. For 31 of the galaxies in our sample we were able to measure the [OIII] ? auroral line at a strength of 4σ or greater, and thus determine oxygen abundances using the direct method. Direct oxygen abundances were compared to B-band luminosity, 4.5 μm luminosity, and stellar mass to characterize the luminosity-metallicity (L-Z) and mass-metallicity (M-Z) relationships at low-luminosity. We examined a "Combined Select” sample composed of 38 objects, from the present sample and the literature, with direct oxygen abundances and reliable distance determinations (based on the tip of the red giant branch or Cepheid variables). The B-band and 4.5 μm L-Z relationships were found to be 12+log(O/H) = (6.19±0.07) + (-0.12±0.01)MB and 12+log(O/H) = (5.93±0.11) + (-0.11±0.01)M[4.5] with dispersions of σ = 0.17 and σ = 0.14 respectively. Since the slope of the L-Z relationship doesn't seem to vary from the optical to the near-IR, as has been observed in studies of more luminous galaxies, we propose that less extinction due to dust is created in the lowest luminosity galaxies. We subsequently derived a M-Z relationship of 12+log(O/H) = (5.49±0.23) + (0.31±0.03)log M*, with a dispersion of σ = 0.16. None of the relationships seem to hold an advantage with respect to dispersion, supporting the idea of minimized dust. Additionally, the trend of N/O abundance with respect to B-V color and oxygen abundance was examined. Similar to the conclusions of van Zee & Haynes (2006), we find a positive correlation between N/O ratio and B-V color: log(N/O) = 0.92 (B-V) - 1.83. Furthermore, there are no objects with high N/O ratio below 12+log(O/H)=7.9.

  4. Transverse emittance growth due to rf noise in the high-luminosity LHC crab cavities

    Science.gov (United States)

    Baudrenghien, P.; Mastoridis, T.

    2015-10-01

    The high-luminosity LHC (HiLumi LHC) upgrade with planned operation from 2025 onward has a goal of achieving a tenfold increase in the number of recorded collisions thanks to a doubling of the intensity per bunch (2.2e11 protons) and a reduction of β* to 15 cm. Such an increase would significantly expedite new discoveries and exploration. To avoid detrimental effects from long-range beam-beam interactions, the half crossing angle must be increased to 295 microrad. Without bunch crabbing, this large crossing angle and small transverse beam size would result in a luminosity reduction factor of 0.3 (Piwinski angle). Therefore, crab cavities are an important component of the LHC upgrade, and will contribute strongly to achieving an increase in the number of recorded collisions. The proposed crab cavities are electromagnetic devices with a resonance in the radio frequency (rf) region of the spectrum (400.789 MHz). They cause a kick perpendicular to the direction of motion (transverse kick) to restore an effective head-on collision between the particle beams, thereby restoring the geometric factor to 0.8 [K. Oide and K. Yokoya, Phys. Rev. A 40, 315 (1989).]. Noise injected through the rf/low level rf (llrf) system could cause significant transverse emittance growth and limit luminosity lifetime. In this work, a theoretical relationship between the phase and amplitude rf noise spectrum and the transverse emittance growth rate is derived, for a hadron machine assuming zero synchrotron radiation damping and broadband rf noise, excluding infinitely narrow spectral lines. This derivation is for a single beam. Both amplitude and phase noise are investigated. The potential improvement in the presence of the transverse damper is also investigated.

  5. AGN BLR structure, luminosity and mass from combined reverberation mapping and optical interferometry observations

    Science.gov (United States)

    Rakshit, Suvendu; Petrov, Romain G.

    2014-07-01

    Unveiling the structure of the Broad-Line Region (BLR) of AGN is critical to understand the quasar phenomenon. Detail study of the geometry and kinematic of these objects can answer the basic questions about the central BH mass, accretion mechanism and rate, growth and evolution history. Observing the response of the BLR clouds to continuum variations, Reverberation Mapping (RM) provides size-luminosity and mass-luminosity relations for QSOs and Sy1 AGNs with the goal to use these objects as standard candles and mass tags. However, the RM size can receive different interpretations depending on the assumed geometry and the corresponding mass depends on an unknown geometrical factor as well on the possible confusion between local and global velocity dispersion. From RM alone, the scatter around the mean mass is as large as a factor 3. Though BLRs are expected to be much smaller than the current spatial resolution of large optical interferometers (OI), we show that differential interferometry with AMBER, GRAVITY and successors can measure the size and constrain the geometry and kinematics on a large sample of QSOs and Sy1 AGNs. AMBER and GRAVITY (K_ 10:5) could be easily extended up to K= 13 by an external coherencer or by advanced "ncoherent" data processing. Future VLTI instrument could reach K~ 15. This opens a large AGN BLR program intended to obtain a very accurate calibration of mass, luminosity and distance measurements from RM data which will allow using many QSOs as standard candles and mass tags to study the general evolution of mass accretion in the Universe. This program is analyzed with our BLR model allowing predicting and interpreting RM and OI measures together and illustrated with the results of our observations of 3C273 with the VLTI.

  6. Properties of Low Luminosity Afterglow Gamma-ray Bursts

    CERN Document Server

    Dereli, H; Gendre, B; Amati, L; Dichiara, S

    2015-01-01

    Aims: We characterize a sample of Gamma-Ray Bursts with low luminosity X-ray afterglows (LLA GRBs), and study their properties. Method: We select a sample consisting of the 12\\% faintest X-ray afterglows from the total population of long GRBs (lGRBs) with known redshift. We study their intrinsic properties (spectral index, decay index, distance, luminosity, isotropic radiated energy and peak energy) to assess whether they belong to the same population than the brighter afterglow events. Results: We present strong evidences that these events belong to a population of nearby events, different from that of the general population of lGRBs. These events are faint during their prompt phase, and include the few possible outliers of the Amati relation. Out of 14 GRB-SN associations, 9 are in LLA GRB sample, prompting for caution when using SN templates in observational and theoretical models for the general lGRBs population.

  7. Decay rates and average luminosity in a B-Factory

    International Nuclear Information System (INIS)

    The different effects contributing to the decay of the electron and positron beam are discussed and the coupled differential equations describing this decay in an asymmetric B-factory are given. The effect of the vacuum pressure rise by gas desorption owing to synchrotron radiation is taken into account. These equations can be solved numerically and the average luminosity can be calculated as function of the running time T for data taking with the filling time F as parameter. The proper choice of T for a given F can optimize the average luminosity. Examples relevant for a B-factory in the ISR tunnel at CERN (BFI) are given, taking into account the constraints of the LEP injector chain, which is proposed to be used also for this collider

  8. Nuclear systematics. Part 3. The source of solar luminosity

    International Nuclear Information System (INIS)

    The Sun emits about 3 x 10431H per year in the solar wind (SW). Solar luminosity and the outflow of SW-protons come from the collapsed supernova core, a neutron star (NS), on which the Sun formed. The universal cradle of the nuclides indicates that the energy of each neutron in the Sun's central NS exceeds that of a free neutron by ∼ 10-22 MeV. Solar luminosity and SW-protons are generated by a series of reactions: (a) escape of neutrons from the central NS, (b) decay of free neutrons or their capture by heavier nuclides, (c) fusion and upward migration of H+ through material that accreted on the NS, and (d) escape of H+ in the SW. (author)

  9. Evidence of an infrared luminosity indicator for galaxies

    International Nuclear Information System (INIS)

    To elucidate the nature of infrared-luminous galaxies discovered with the IRAS satellite, the optical and infrared luminosities of 1161 Markarian galaxies and 2146 normal galaxies from the CfA redshift survey are compared. Survival analysis statistical methods that take upper limits fully into account are used. It is found that L(IR)/L(B) is statistically correlated with L(60) in both samples, though they differ in the distribution at low luminosities. The derived correlation shows that L(IR)/L(B) provides an indicator for L(60). Since galaxies selected in unbiased IRAS surveys will have higher L(IR)/L(B) than optically selected galaxies, they are therefore also selected for high L(60). 22 references

  10. The FCC-ee design study: luminosity and beam polarization

    CERN Document Server

    Koratzinos, M

    2015-01-01

    The FCC-ee accelerator is considered within the FCC design study as a possible first step towards the ultimate goal of a 100 TeV hadron collider. It is a high luminosity e+e- storage ring collider, designed to cover energies of around 90, 160, 240 and 350GeV ECM (for the Z peak, the WW threshold, the ZH and ttbar cross-section maxima respectively) leading to different operating modes. We report on the current status of the design study, on the most promising concepts and relevant challenges. The expected luminosity performance at all energies, and first studies on transverse polarization for beam energy calibrations will be presented.

  11. Bivariate Galaxy Luminosity Functions in the Sloan Digital Sky Survey

    OpenAIRE

    Ball, N M; Loveday, J.; Brunner, R. J.; Baldry, I. K.; Brinkmann, J.

    2005-01-01

    Bivariate luminosity functions (LFs) are computed for galaxies in the New York Value-Added Galaxy Catalogue, based on the Sloan Digital Sky Survey Data Release 4. The galaxy properties investigated are the morphological type, inverse concentration index, Sersic index, absolute effective surface brightness, reference frame colours, absolute radius, eClass spectral type, stellar mass and galaxy environment. The morphological sample is flux-limited to galaxies with r < 15.9 and consists of 37,04...

  12. LHC abort gap cleaning studies during luminosity operation

    CERN Document Server

    Bartmann, W; Bracco, C; Bravin, E; Goddard, B; Höfle, W; Jacquet, D; Jeff, A; Kain, V; Meddahi, M; Roncarolo, F; Uythoven, J; Valuch, D; Gianfelice-Wendt, E

    2012-01-01

    The presence of significant intensities of un-bunched beam is a potentially serious issue in the LHC. Procedures using damper kickers for cleaning both the Abort Gap (AG) and the buckets targeted for injection, are currently in operation at flat bottom. Recent observations of relatively high population of the AG during physics runs brought up the need for AG cleaning during luminosity operation. In this paper the results of experimental studies performed in October 2011 are presented.

  13. Luminosity measurement in the charmonium experiment (antipp → cantic)

    International Nuclear Information System (INIS)

    We have exposed the determination of the luminosity by the study of the differential cross section dσ/dt of the elastic pantip reaction. We try to extract the two parameters which characterize the nuclear amplitude: the slope b and the ratio rho of the real part to the imaginary part of this amplitude. Those preliminary values of b and rho are in agreement with precedent data

  14. Correlation Analysis of Multi-Wavelength Luminosity of Fermi Blazars

    Indian Academy of Sciences (India)

    Xiongwei Bi; Wanquan He; Jiajin Tian; Zhimei Ding; Shuping Ge

    2014-09-01

    We have studied the correlations between luminosities (R, O, X, ) in radio, optical, X-ray and -ray wave bands for Fermi blazars, and found that there are significant correlations between R and , X and and O and for blazars, BL Lacs and FSRQs, but no correlation between and O for BL Lacs. These results suggest that for Fermi blazars, the high energy -ray emission can be related with radio, X-ray and optical emissions.

  15. Toward better simulations of planetary nebulae luminosity functions

    OpenAIRE

    Mendez, R. H.; A. M. Teodorescu; Schoenberner, D; Jacob, R; Steffen, M.

    2008-01-01

    We describe a procedure for the numerical simulation of the planetary nebulae luminosity function (PNLF), improving on previous work (Mendez & Soffner 1997). Earlier PNLF simulations were based on an imitation of the observed distribution of the intensities of [O III] 5007 relative to Hbeta, generated predominantly using random numbers. We are now able to replace this by a distribution derived from the predictions of hydrodynamical PN models (Schoenberner et al. 2007), which are made to evolv...

  16. KEKB records 10^34/cm^2s luminosity

    CERN Multimedia

    2003-01-01

    "On May 9, 2003, the KEKB accelerator at the High Energy Accelerator Research Organization in Tsukuba, Japan, achieved a major break- through by being the first colliding-beam facility to attain a peak luminosity above 10^34/cm^2s, a long-sought milestone in accelerator physics. This historic accomplishment highlights KEK's role as one of the world's premier laboratories for accelerator-based science" (1 page).

  17. ATLAS Inner Tracker Upgrade Simulations for High-Luminosity LHC

    CERN Document Server

    Gregor, IM; The ATLAS collaboration; Wang, J

    2013-01-01

    Design of new ATLAS Inner Tracker for the High-Luminosity LHC Upgrade is based on detailed simulation of layout geometries. It should satisfy challenging operation and performance requirements: tracks and vertices reconstruction in presence of up to 200 collisions in an event, high radiation doses and up to 12 years of operation. Advanced studies of the existing layout and plans for development of new ones will be presented.

  18. ATLAS Inner Tracker Upgrade Simulation for High-Luminosity LHC

    CERN Document Server

    Burdin, S; The ATLAS collaboration; Hayward, H; Styles, N

    2013-01-01

    Design of new ATLAS Inner Tracker for the High-Luminosity LHC Upgrade is based on detailed simulation of layout geometries. It should satisfy challenging operation and performance requirements: tracks and vertices reconstruction in presence of up to 200 collisions in an event, high radiation doses and up to 12 years of operation. Advanced studies of the existing layout and plans for development of new ones will be presented.

  19. Dynamic aperture studies for the LHC high luminosity lattice

    Energy Technology Data Exchange (ETDEWEB)

    Maria, R. de [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Giovannozzi, M. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); McIntosh, E. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Nosochkov, Y. M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Cai, Y. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Wang, M. -H. [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-07-14

    Since quite some time, dynamic aperture studies have been undertaken with the aim of specifying the required field quality of the new magnets that will be installed in the LHC ring in the framework of the high-luminosity upgrade. In this paper the latest results concerning the specification work will be presented, taking into account both injection and collision energies and the field quality contribution from all the magnets in the newly designed interaction regions.

  20. Tertiary Education and Prosperity: Catholic Missionaries to Luminosity in India

    OpenAIRE

    Castelló-Climent, Amparo; Chaudhary, Latika; Mukhopadhyay, Abhiroop

    2015-01-01

    This paper estimates the causal impact of tertiary education on luminosity across Indian districts. We address the potential endogeneity of tertiary education using the location of Catholic missionaries in 1911 as an instrument for current tertiary education. We find Catholic missionaries have a large and positive impact on tertiary education. Catholics were not at the forefront of tertiary education in colonial India, but they established many high quality colleges following Indian independ...

  1. HI in Low-Luminosity Early-Type Galaxies

    OpenAIRE

    Oosterloo, Tom; Morganti, Raffaella; Sadler, Elaine

    1998-01-01

    We discuss the properties of the HI in low-luminosity early-type galaxies. The morphology of the HI is more regular than that of the HI in many more-luminous early-type galaxies. The HI is always distributed in a disk and is more centrally concentrated. The central HI surface densities are higher than in luminous early-type galaxies and are high enough for star formation to occur.

  2. Electron-cloud effects in high-luminosity colliders

    International Nuclear Information System (INIS)

    Electron-cloud instabilities are expected to be important in most high-luminosity double-ring colliders. In this report, the author describes a few parameter regimes and some critical parameter dependences of this type of instability, and illustrate these with simulation results for the PEP-II and KEK B factories, the LHC, the VLHC, and DAPHNE. In addition, the author studies the possibility and the potential impact of an electron cloud in the interaction region

  3. The Luminosity and Redshift Distributions of Short-Duration GRB

    OpenAIRE

    Guetta, Dafne(INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00040 Monteporzio Catone, Italy); Piran, Tsvi

    2004-01-01

    Using the BATSE peak flux distribution we rederive the short GRBs luminosity function and compare it with the observed redshift distribution of long bursts. We show that both distributions are compatible with the assumption that short as well as long bursts follow the star formation rate. In this case the difference between the two observed distributions can be interpreted as arising mostly from differences in the detector's sensitivity to long and short bursts, while the local rate of short ...

  4. Size and Kinetic Luminosity of Low Redshift Quasar Outflows

    Science.gov (United States)

    Arav, Nahum

    2011-01-01

    Over the past several months the new UV spectrograph aboard HST is giving us high quality data of AGN outflows, aka warm absorbers to the X-ray community. I will describe very new results from our program that aim at finding the size, kinetic luminosity and chemical abundances of these outflows. We acknowledge support from NASA through HST program (11686), and from NSF grant AST 0837880.

  5. Dynamic Aperture Studies for the LHC High Luminosity Lattice

    CERN Document Server

    De Maria, R; Giovannozzi, Massimo; Mcintosh, Eric; Cai, Y; Nosochkov, Y; Wang, M H

    2015-01-01

    Since quite some time, dynamic aperture studies have been undertaken with the aim of specifying the required field quality of the new magnets that will be installed in the LHC ring in the framework of the high-luminosity upgrade. In this paper the latest results concerning the specification work will be presented, taking into account both injection and collision energies and the field quality contribution from all the magnets in the newly designed interaction regions.

  6. The luminosity function at z ∼ 8 from 97 Y-band dropouts: Inferences about reionization

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Kasper B.; Treu, Tommaso; Kelly, Brandon C. [Department of Physics, University of California, Santa Barbara, CA 93106-9530 (United States); Trenti, Michele [Kavli Institute for Cosmology and Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Bradley, Larry D.; Stiavelli, Massimo [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Oesch, Pascal A. [UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Holwerda, Benne W. [Leiden Observatory, Leiden University, NL-2300 RA Leiden (Netherlands); Shull, J. Michael, E-mail: kschmidt@physics.ucsb.edu [CASA, Department of Astrophysical and Planetary Science, University of Colorado, Center for Astrophysics and Space Astronomy, 389-UCB, Boulder, CO 80309 (United States)

    2014-05-01

    We present the largest search to date for Y-band dropout galaxies (z ∼ 8 Lyman break galaxies, LBGs) based on 350 arcmin{sup 2} of Hubble Space Telescope observations in the V, Y, J, and H bands from the Brightest of Reionizing Galaxies (BoRG) survey. In addition to previously published data, the BoRG13 data set presented here includes approximately 50 arcmin{sup 2} of new data and deeper observations of two previous BoRG pointings, from which we present 9 new z ∼ 8 LBG candidates, bringing the total number of BoRG Y-band dropouts to 38 with 25.5 ≤ m{sub J} ≤ 27.6 (AB system). We introduce a new Bayesian formalism for estimating the galaxy luminosity function, which does not require binning (and thus smearing) of the data and includes a likelihood based on the formally correct binomial distribution as opposed to the often-used approximate Poisson distribution. We demonstrate the utility of the new method on a sample of 97 Y-band dropouts that combines the bright BoRG galaxies with the fainter sources published in Bouwens et al. from the Hubble Ultra Deep Field and Early Release Science programs. We show that the z ∼ 8 luminosity function is well described by a Schechter function over its full dynamic range with a characteristic magnitude M{sup ⋆}=−20.15{sub −0.38}{sup +0.29}, a faint-end slope of α=−1.87{sub −0.26}{sup +0.26}, and a number density of log{sub 10} ϕ{sup ⋆}[Mpc{sup −3}]=−3.24{sub −0.24}{sup +0.25}. Integrated down to M = –17.7, this luminosity function yields a luminosity density log{sub 10} ϵ[erg s{sup −1} Hz{sup −1} Mpc{sup −3}]=25.52{sub −0.05}{sup +0.05}. Our luminosity function analysis is consistent with previously published determinations within 1σ. The error analysis suggests that uncertainties on the faint-end slope are still too large to draw a firm conclusion about its evolution with redshift. We use our statistical framework to discuss the implication of our study for the physics of reionization. By assuming theoretically motivated priors on the clumping factor and the photon escape fraction we show that the UV luminosity density from galaxy samples down to M = –17.7 can ionize only 10%-50% of the neutral hydrogen at z ∼ 8. Full reionization would require extending the luminosity function down to M = –15. The data are consistent with a substantial fraction of neutral hydrogen at z > 7, in agreement with recent suggestions based on deep spectroscopy of z ∼ 8 LBGs.

  7. Cosmological simulations of black hole growth: AGN luminosities and downsizing

    CERN Document Server

    Michaela, Hirschmann; Alexandro, Saro; Stefano, Borgani; Andreas, Burkert

    2013-01-01

    In this study, we present a detailed, statistical analysis of black hole (BH) growth and the evolution of active galactic nuclei (AGN) using cosmological hydrodynamic simulations run down to z=0. The simulations self-consistently follow radiative cooling, star formation, metal enrichment, BH growth and associated feedback processes from both supernovae typeII/Ia and AGN. We consider two simulation runs, one with a large co-moving volume of (128 Mpc/h)^3 and one with a smaller volume of (48 Mpc/h)^3 but with a higher mass resolution. Consistently with previous results, our simulations are in reasonably good agreement with BH properties of the local Universe. Furthermore, they can successfully reproduce the evolution of the bolometric AGN luminosity function for both the low- and the high-luminosity end up to z=2.5. The smaller but higher resolution run can match the observational data of the low bolometric luminosity end even up to z=4-5. We also perform a direct comparison with the observed soft and hard X-ra...

  8. Luminosities of Barred and Unbarred S0 Galaxies

    CERN Document Server

    Bergh, Sidney van den

    2012-01-01

    Lenticular galaxies with M_B < -21.5 are almost exclusively unbarred, whereas both barred and unbarred objects occur at fainter luminosity levels. This effect is observed both for objects classified in blue light, and for those that were classified in the infrared. This result suggests that the most luminous (massive) S0 galaxies find it difficult to form bars. As a result the mean luminosity of unbarred lenticular galaxies in both B and IR light is observed to be ~0.4 mag brighter than than that of barred lenticulars. A small contribution to the observed luminosity difference that is found between SA0 and SB0 galaxies may also be due to the fact that there is an asymmetry between the effects of small classification errors on SA0 and SB0 galaxies. An E galaxy might be misclassified as an S0, or an S0 as an E. However, an E will never be misclassified an SB0, nor will an SB0 ever be called an E. This asymmetry is important because elliptical (E) galaxies are typically twice as luminous as lenticular (S0) ga...

  9. The Black Hole Mass - Galaxy Luminosity Relationship for SDSS Quasars

    CERN Document Server

    Salviander, S; Bonning, E W

    2014-01-01

    We investigate the relationship between the mass of the central supermassive black hole, M_bh, and the host galaxy luminosity, L_gal, in a sample of quasars from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7). We use composite quasar spectra binned by black hole mass and redshift to assess galaxy features that would otherwise be overwhelmed by noise in individual spectra. The black hole mass is calculated using the photoionization method, and the host galaxy luminosity is inferred from the depth of the Ca II H + K features in the composite spectra. We evaluate the evolution in the M_bh - L_gal relationship by examining the redshift dependence of Delta log M_bh, the offset in black hole mass from the local black hole - bulge relationship. There is little systematic trend in Delta log M_bh out to z = 0.8. Using the width of the [O III] emission line as a proxy for the stellar velocity dispersion, sigma_*, we find agreement of our derived host luminosities with the locally-observed Faber-Jackson relati...

  10. VV 114, a high infrared luminosity interacting galaxy system

    Science.gov (United States)

    Knop, R. A.; Soifer, B. T.; Graham, J. R.; Matthews, K.; Sanders, D. B.; Scoville, N. Z.

    1994-01-01

    VV 114 is a nearby example of a far-infrared (FIR) bright, high luminosity (L(sub FIR) greater than 10(exp 11) solar luminosity) interacting galaxy pair. At a redshift of z = 0.02 it provides an opportunity to study such interacting galaxies at a favorable spatial scale (390 pc/arcsec). This paper presents new high resolution near-infrared (1.25 to 3.7 micrometer) and visible images, and visible spectra of VV 114. A picture emerges of a system with widespread massive star formation throughout both interacting galaxies. The brighter visible galaxy (VV 114W) shows H II region-like emission in both visual spectra and near-infrared colors, with no more than two magnitudes of visual extinction. The brightest peak of infrared and radio emission (VV 114E) has extreme near-infrared colors and is located at a minimum of visible emission. This indicates a large concentration of dust in the nucleus of VV 114E that is nearly entirely obscuring a major luminosity source in this system.

  11. The graviton luminosity of the sun and other stars

    Science.gov (United States)

    Gould, R. J.

    1985-01-01

    Graviton production in electron-electron (e-e) and electron-ion (e-z) scattering is evaluated in the Born approximation. The calculation is compared with that for photon production, that is, Coulomb quadrupole bremsstrahlung, and a number of results are taken over from that problem. Application is made to the sun, and it is found that for the solar plasma the main contribution to the graviton luminosity comes from the central core at r/R approximately 0.1. The total luminosity (Lg) in gravitons is about 7.9 x 10 to the 14th ergs/s, close to an earlier estimate by Weinberg (1965, 1972); about 33 percent of the total results from e-e collisions with the rest from e-z collisions (mainly e-p and e-alpha). Approximate corrections to Born formulas are evaluated, and this Lg includes the associated (approximately + or - 10 percent, respectively) modification. The quantum-mechanical aspects of the solar Lg problem are discussed, and it is shown why a previous classical calculation overestimated Lg by about an order of magnitude. Production of gravitons in binary collisions in other types of stars is discussed briefly. It is found that Lg varies very little along the main sequence. White dwarfs have a typical graviton luminosity LWD approximately 10 to the 19th ergs/s, while neutron stars have LNS approximately 10 to the 25th ergs/s; these estimates are very rough.

  12. Applying the luminosity function statistics in the fireshell model

    Science.gov (United States)

    Rangel Lemos, L. J.; Bianco, C. L.; Ruffini, R.

    2015-12-01

    The luminosity function (LF) statistics applied to the data of BATSE, GBM/Fermi and BAT/Swift is the theme approached in this work. The LF is a strong statistical tool to extract useful information from astrophysical samples, and the key point of this statistical analysis is in the detector sensitivity, where we have performed careful analysis. We applied the tool of the LF statistics to three GRB classes predicted by the Fireshell model. We produced, by LF statistics, predicted distributions of: peak ux N(Fph pk), redshift N(z) and peak luminosity N(Lpk) for the three GRB classes predicted by Fireshell model; we also used three GRB rates. We looked for differences among the distributions, and in fact we found. We performed a comparison between the distributions predicted and observed (with and without redshifts), where we had to build a list with 217 GRBs with known redshifts. Our goal is transform the GRBs in a standard candle, where a alternative is find a correlation between the isotropic luminosity and the Band peak spectral energy (Liso - Epk).

  13. THE z = 5 QUASAR LUMINOSITY FUNCTION FROM SDSS STRIPE 82

    International Nuclear Information System (INIS)

    We present a measurement of the Type I quasar luminosity function at z = 5 using a large sample of spectroscopically confirmed quasars selected from optical imaging data. We measure the bright end (M1450 2, then extend to lower luminosities (M1450 2 of deep, coadded imaging in the SDSS Stripe 82 region (the celestial equator in the Southern Galactic Cap). The faint sample includes 14 quasars with spectra obtained as ancillary science targets in the SDSS-III Baryon Oscillation Spectroscopic Survey, and 59 quasars observed at the MMT and Magellan telescopes. We construct a well-defined sample of 4.7 1450*∼-27). The bright-end slope is steep (β ∼1450 < –26) from z = 5 to z = 6 than from z = 4 to z = 5, suggesting a more rapid decline in quasar activity at high redshift than found in previous surveys. Our model for the quasar luminosity function predicts that quasars generate ∼30% of the ionizing photons required to keep hydrogen in the universe ionized at z = 5.

  14. An ionization chamber shower detector for the LHC luminosity monitor

    CERN Document Server

    Beche, J F; Datte, P S; Haguenauer, Maurice; Manfredi, P F; Millaud, J E; Placidi, Massimo; Ratti, L; Re, V; Riot, V J; Schmickler, Hermann; Speziali, V; Turner, W C

    2000-01-01

    The front IR quadrupole absorbers (TAS) and the IR neutral particle absorbers (TAN) in the high luminosity insertions of the Large Hadron Collider (LHC) each absorb approximately 1.8 TeV of forward collision products on average per pp interaction (~235 W at design luminosity 10/sup 34/ cm/sup -2/ s/sup -1/). This secondary particle flux can be exploited to provide a useful storage ring operations tool for optimization of luminosity. A novel segmented, multi-gap, pressurized gas ionization chamber is being developed for sampling the energy deposited near the maxima of the hadronic/electromagnetic showers in these absorbers. The system design choices have been strongly influenced by optimization of signal to noise ratio and by the very high radiation environment. The ionization chambers are instrumented with low noise, fast, pulse shaping electronics to be capable of resolving individual bunch crossings at 40 MHz. Data on each bunch are to be separately accumulated over multiple bunch crossings until the desire...

  15. The GRB variability/peak luminosity correlation: new results

    International Nuclear Information System (INIS)

    We test the correlation between time variability and isotropic-equivalent peak luminosity found by Reichart et al. (ApJ, 552 (2001) 57) using a set of 26 Gamma-Ray Bursts (GRBs) with known redshift. We confirm the correlation, thought with a larger spread around the best-fit power-law obtained by Reichart et al. which in turn does not provide an acceptable description any longer. In addiction, we find no evidence for correlation between variability and beaming-corrected peak luminosity for a subset of 14 GRBs whose beaming angles have been taken from Ghirlanda et al. (ApJ, 616 (2004) 331). Finally, we investigate the possible connection for some GRBs between the location in the variability/peak luminosity space and some afterglow properties, such as the detectability in the optical band, by adding some GRBs whose redshifts, unknown from direct measurements, have been derived assuming the Amati at al. (AeA, 390 (2002) 81) relationship

  16. Beam dynamics studies to develop LHC luminosity model

    CERN Document Server

    Campogiani, Giovanna; Papaphilippou, Ioannis

    The thesis project aims at studying the different physical processes that are impacting luminosity, one of the key figures of merit of a collider operation. In particular the project focuses on extracting the most relevant parameters for the high-energy part of the model, which is mostly dominated by the beam-beam effect. LHC luminosity is degraded by parasitic collisions that reduce the beam lifetime and the particles stability in the collider. This instability is due to the non-linear effects of one beam electromagnetic field on another in the interaction region. Such parasitic encounters can be as many as 16 per interaction region, piling up to around 180 000 per second. Our goal is to study the evolution of charge density distribution in the beam, by tracking particles through a symplectic integrator that includes the beam-beam effect. In particular we want to obtain data on the halo particles, which are more sensible to instability, to better characterise the beam lifetime and monitor the luminosity evol...

  17. Precision luminosity measurement at LHCb with beam-gas imaging

    CERN Document Server

    Barschel, Colin

    The luminosity is the physical quantity which relates the cross-section to the production rate in collider experiments. The cross-section being the particle physics observable of interest, a precise determination of the luminosity is required. This work presents the absolute luminosity calibration results performed at the Large Hadron Collider beauty (LHCb) experiment at CERN using a novel method based on beam-gas interactions with data acquired at a center of mass energy $\\sqrt{s}=8$ TeV and $\\sqrt{s}=2.76$ TeV. Reconstructed beam-gas interaction vertices in LHCb are used to measure the beam profiles, thus making it possible to determine the beams overlap integral. An important element of this work was to install and use a neon gas injection system to increase the beam-gas interaction rate. The precision reached with the beam-gas imaging method relies on the two-dimensional beam shape determination developed in this work. For such precision, the interaction vertex resolution is an important ingredient. There...

  18. Shapley Optical Survey. I: Luminosity Functions in the Supercluster Environment

    CERN Document Server

    Mercurio, A; Haines, C P; Gargiulo, A; Krusanova, N; Busarello, G; La Barbera, F; Capaccioli, M; Covone, G

    2006-01-01

    We present the Shapley Optical Survey, a photometric study covering a 2 deg^2 region of the Shapley Supercluster core at z ~ 0.05 in two bands (B and R). The galaxy sample is complete to B=22.5 (>M^*+6, N_{gal}=16588), and R=22.0 (>M^*+7, N_{gal}=28008). The galaxy luminosity function cannot be described by a single Schechter function due to dips apparent at B ~ 17.5 (M_B ~ -19.3) and R ~ 17.0 (M_R ~ -19.8) and the clear upturn in the counts for galaxies fainter than B and R ~18 mag. We find, instead, that the sum of a Gaussian and a Schechter function, for bright and faint galaxies respectively, is a suitable representation of the data. We study the effects of the environment on the photometric properties of galaxies, deriving the galaxy luminosity functions in three regions selected according to the local galaxy density, and find a marked luminosity segregation, in the sense that the LF faint-end is different at more than 3sigma confidence level in regions with different densities. In addition, the luminosi...

  19. AGN BLR structure, luminosity and mass from combined Reverberation Mapping and Optical Interferometry observations

    CERN Document Server

    Rakshit, Suvendu

    2014-01-01

    Unveiling the structure of the Broad Line Region (BLR) of AGN is critical to understand the quasar phenomenon. Detail study of the geometry and kinematic of these objects can answer the basic questions about the central BH mass, accretion mechanism and rate, growth and evolution history. Observing the response of the BLR clouds to continuum variations, Reverberation Mapping (RM) provides size vs luminosity and mass vs luminosity relations for QSOs and Sy1 AGNs with the goal to use these objects as standard candles and mass tags. However, the RM size can receive different interpretations depending on the assumed geometry and the corresponding mass depends on an unknown geometrical factor as well on the possible confusion between local and global velocity dispersion. From RM alone, the scatter around the mean mass is as large as a factor 3. Though BLRs are expected to be much smaller than the current spatial resolution of large optical interferometers (OI), we show that differential interferometry with AMBER, G...

  20. A new model of galaxy formation: How sensitive are predicted galaxy luminosities to the choice of SPS model?

    CERN Document Server

    V.,; Lacey, C G; Baugh, C M; Lagos, C D P; Helly, J; Campbell, D J R

    2013-01-01

    We present a new release of the GALFORM semi-analytical model of galaxy formation and evolution, which exploits a Millennium Simulation-class N-body run performed with the WMAP7 cosmology. We use this new model to study the impact of the choice of stellar population synthesis (SPS) model on the predicted evolution of the galaxy luminosity function. The semi-analytical model is run using seven different SPS models. In each case we obtain the rest-frame luminosity function in the far-ultra-violet, optical and near-infrared (NIR) wavelength ranges. We find that both the predicted rest-frame ultra-violet and optical luminosity function are insensitive to the choice of SPS model. However, we find that the predicted evolution of the rest-frame NIR luminosity function depends strongly on the treatment of the thermally pulsating asymptotic giant branch (TP-AGB) stellar phase in the SPS models, with differences larger than a factor of 2 for model galaxies brighter than K(AB)-5logh<-22 (about L* for 0 < z < 1....

  1. The VIMOS-VLT Deep Survey: Evolution of the galaxy luminosity function up to z=2 in first epoch data

    CERN Document Server

    Ilbert, O; Zucca, E; Bardelli, S; Arnouts, S; Zamorani, G; Pozzetti, L; Bottini, D; Garilli, B; Le Brun, V; Lefvre, O; MacCagni, D; Picat, J P; Scaramella, R; Scodeggio, M; Vettolani, G; Zanichelli, A; Adami, C; Arnaboldi, M; Bolzonella, M; Cappi, A; Charlot, S; Contini, T; Foucaud, S; Franzetti, P; Gavignaud, I; Guzzo, L; Iovino, A; McCracken, H J; Marano, B; Marinoni, C; Mathez, G; Mazure, A; Meneux, B; Merighi, R; Paltani, S; Pell, R; Pollo, A; Radovich, M; Bondi, M; Bongiorno, A; Busarello, G; Ciliegi, P; Mellier, Y; Merluzzi, P; Ripepi, V; Rizzo, D

    2004-01-01

    We investigate the evolution of the galaxy luminosity function from the VIMOS-VLT Deep Survey (VVDS) from the present to z=2 in five (U, B, V, R and I) rest-frame band-passes. We use the first epoch VVDS deep sample of 11,034 spectra selected at 17.5 <= I_{AB} <= 24.0, on which we apply the Algorithm for Luminosity Function (ALF), described in this paper. We observe a substantial evolution with redshift of the global luminosity functions in all bands. From z=0.05 to z=2, we measure a brightening of the characteristic magnitude M* included in the magnitude range 1.8-2.4, 1.6-2.2, 1.0-1.7, 0.9-1.6 and 0.8-1.4 in the U, B, V, R and I rest-frame bands, respectively. We confirm this differential evolution of the luminosity function with rest-frame wavelength, from the measurement of the comoving density of bright galaxies (M < M*(z=0.1)). This density increases by a factor of around 2.5, 2.2, 1.7, 1.4, 1.3 between z=0.05 and z=1 in the U, B, V, R, I bands, respectively. We also measure a possible steepeni...

  2. A composite plot of far-infrared versus radio luminosity, and the origin of far-infrared luminosity in quasars

    International Nuclear Information System (INIS)

    We have constructed a composite plot of far-infrared versus radioluminosity for late-type galaxies, Seyferts, quasars and radio galaxies. The most striking result is that the radio and far-infrared luminosities of radio-quiet quasars are correlated and follow the same correlation as normal star-forming galaxies and ultra-luminous infrared galaxies, whereas the radio-loud quasars have luminosities in both bands similar to those of radio galaxies. We conclude that the far-infrared emission from radio-quiet quasars is from star-forming host galaxies and not from active galactic nuclei. The far-infrared radio plot may be a powerful discriminator between host galaxy type. (author)

  3. The IRAS bright galaxy sample. II - The sample and luminosity function

    Science.gov (United States)

    Soifer, B. T.; Sanders, D. B.; Neugebauer, G.; Madore, B. F.; Danielson, G. E.

    1987-01-01

    A statistically complete sample of 324 of the brightest infrared galaxies discovered at 60 microns in the IRAS all-sky survey is described. The results show that far-infrared emission is a significant luminosity component in the local universe, representing 25 percent of the luminosity emitted by stars in the same volume. Above 10 to the 11th solar luminosities, the infrared luminous galaxies are the dominant population of objects in the universe, being as numerous as the Seyfert galaxies and more numerous than quasars at higher luminosities. The infrared luminosity appears to be independent of the optical luminosity of galaxies. Most infrared bright galaxies appear to require much of the interstellar matter to be contributing to the observed infrared luminosity. Approximately 60-80 percent of the far-infrared luminosity of the local universe can be attributed, directly or indirectly, to recent or ongoing star formation.

  4. Very Low Luminosity Objects in Taurus Molecular Cloud

    Science.gov (United States)

    Sung, Ren-Shiang; Lai, Shih-Ping

    2015-08-01

    Very Low Luminosity Objects (VeLLOs) are the faintest protostars with intrinsic luminosity Lint ? 0.1 L?. Their low luminosities hints that they could be either very young, very low-mass, or even very young and low-mass protostars (i.e., proto brown dwarfs). Thus, identifying VeLLOs and investigating their properties are crucial for fully understanding of the earliest stage of star formation. The goal of this paper is to uncover VeLLOs in the Taurus molecular cloud and confirm that they are true Young Stellar Objects (YSOs). We use the catalogue from Taurus Spitzer Legacy Project and apply the selection criteria developed by Dunham et al. (2008) which are based on the Spectral Energy Distributions (SEDs) of typical Class 0 and early Class I protostars. New criteria for bolometric temperature and extinction are included to make up the lack of complete coverage of submm/mm maps in Taurus. As a result, we select 10 VeLLO candidates. In order to verify our VeLLO candidates are real YSOs, we observe 13CO (J=2-1), C18O (J=1-0), N2D+ (J=2-1), N2D+ (J=3-2), and N2H+ (J=1-0) with Arizona Radio Observatory (ARO). We detect N2H+ and N2D+ (J=2-1) in four VeLLO candidates and 13CO and C18O in all 10 VeLLO candidates (except SL05). We have also obtained SMA CO (J=2-1) maps toward the four VeLLOs with N2H+ and N2D+ detections to investigate their outflow properties. Based on the result of the N2D+/N2H+ column density ratio, two VeLLO candidates could be very young protostars and the other eight are more likely to be very low-mass protostars.

  5. LUMINOSITIES OF BARRED AND UNBARRED S0 GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Van den Bergh, Sidney, E-mail: sidney.vandenbergh@nrc.gc.ca [Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada)

    2012-07-20

    Lenticular galaxies with M{sub B} < -21.5 are almost exclusively unbarred, whereas both barred and unbarred objects occur at fainter luminosity levels. This effect is observed both for objects classified in blue light, and for those that were classified in the infrared. This result suggests that the most luminous (massive) S0 galaxies find it difficult to form bars. As a result, the mean luminosity of unbarred lenticular galaxies in both B and IR light is observed to be {approx}0.4 mag brighter than that of barred lenticulars. A small contribution to the observed luminosity difference that is found between SA0 and SB0 galaxies may also be due to the fact that there is an asymmetry between the effects of small classification errors on SA0 and SB0 galaxies. An elliptical (E) galaxy might be misclassified as a lenticular (S0) or an S0 as an E. However, an E will never be misclassified as an SB0, nor will an SB0 ever be called an E. This asymmetry is important because E galaxies are typically twice as luminous as S0 galaxies. The present results suggest that the evolution of luminous lenticular galaxies may be closely linked to that of elliptical galaxies, whereas fainter lenticulars might be more closely associated with ram-pressure stripped spiral galaxies. Finally, it is pointed out that fine details of the galaxy formation process might account for some of the differences between the classifications of the same galaxy by individual competent morphologists.

  6. LUMINOSITIES OF BARRED AND UNBARRED S0 GALAXIES

    International Nuclear Information System (INIS)

    Lenticular galaxies with MB < –21.5 are almost exclusively unbarred, whereas both barred and unbarred objects occur at fainter luminosity levels. This effect is observed both for objects classified in blue light, and for those that were classified in the infrared. This result suggests that the most luminous (massive) S0 galaxies find it difficult to form bars. As a result, the mean luminosity of unbarred lenticular galaxies in both B and IR light is observed to be ∼0.4 mag brighter than that of barred lenticulars. A small contribution to the observed luminosity difference that is found between SA0 and SB0 galaxies may also be due to the fact that there is an asymmetry between the effects of small classification errors on SA0 and SB0 galaxies. An elliptical (E) galaxy might be misclassified as a lenticular (S0) or an S0 as an E. However, an E will never be misclassified as an SB0, nor will an SB0 ever be called an E. This asymmetry is important because E galaxies are typically twice as luminous as S0 galaxies. The present results suggest that the evolution of luminous lenticular galaxies may be closely linked to that of elliptical galaxies, whereas fainter lenticulars might be more closely associated with ram-pressure stripped spiral galaxies. Finally, it is pointed out that fine details of the galaxy formation process might account for some of the differences between the classifications of the same galaxy by individual competent morphologists.

  7. LUMINOSITY FUNCTIONS OF TYPE Ia SUPERNOVAE AND THEIR HOST GALAXIES FROM THE SLOAN DIGITAL SKY SURVEY

    International Nuclear Information System (INIS)

    The sample of 137 low-redshift type Ia supernovae (SNe Ia) with 0.05 ≤ z ≤ 0.3 obtained from the Sloan Digital Sky Survey (SDSS)-II supernova survey for the southern equatorial stripe of 300 deg2 is used to derive the luminosity functions (LFs) of SNe Ia and of their host galaxies in the g, r, i passbands. We show that the LF of SNe Ia host galaxies matches well with that of galaxies in the general field, suggesting that the occurrence of SNe Ia does not favor a particular type of galaxy but is predominantly proportional to the luminosity of galaxies. The evidence is weak that the SNe rate varies with the color of host galaxies. The only evidence that points to possible correlation between the SN rate and star formation activity is that the SN rate in late-type galaxies is higher than that in early-type galaxies by 31% ± 35%. In our low-redshift sample, the component of type Ia SN rate that is proportional to star formation activity is not evident in the integrated SN rate, while our observation is compatible with the current two-component models. The sample contains eight SNe Ia whose host galaxies were not identified, but it is shown that their occurrence is consistent with them occurring in low-luminous galaxies beyond the survey. The LF of SNe Ia is approximately Gaussian with the full width at half-maximum being a factor of σ = 0.24 mag or 1.67 in luminosity. The Gaussian distribution becomes tighter if the ratio of extinction to reddening, RV , is lower than the characteristic value for the Milky Way and if luminosity is corrected for the light-curve shape. The average color excess is ∼0.07 mag, which is significantly smaller than reddening expected for field galaxies. This color excess does not vary with the distance of the SNe from the center of the host galaxy to 15 kpc. This suggests that the major part of the color excess appears to be either intrinsic or reddening that arises in the immediate environment of SNe, rather than interstellar reddening in host galaxies, and most of SNe Ia take place in a relatively dust-free environment.

  8. RESULTS FROM LUMINOSITY SCANS DURING THE RHIC 2000 RUN.

    Energy Technology Data Exchange (ETDEWEB)

    DREES,A.; XU,Z.

    2001-06-18

    During the year 2000 run a total of eight beam scans (Vernier Scans) were performed at various interaction points (IF) at RHIC. During a Vernier Scan the experimental collision rates are recorded while the beams are stepwise scanned across each other. Vernier Scans yield transverse beam sizes as well as maximum luminosity and thus the absolute cross section, which with the limited data from the 2000 run we measured to be {sigma} = 8.9 {+-} 0.3 barn at ({radical}s{sub NN}) = 130 GeV. Also, Vernier Scans permit performance studies of the beam orbit control and local coupling.

  9. Radiation environment and shielding for a high luminosity collider detector

    International Nuclear Information System (INIS)

    Detectors now under design for use in the proposed high energy high luminosity colliders must deal with unprecedented radiation levels. We have performed a comprehensive study for the GEM detector at the SSC to determine the best way to shield critical detector components from excessive radiation, with special attention paid to the low energy neutrons and photons. We have used several detailed Monte-Carlo simulations to calculate the particle fluxes in the detector. We describe these methods and demonstrate that two orders of magnitude reduction in the neutron and photon fluxes can be obtained with appropriate shielding of critical forward regions such as the low beta quadrupoles and the forward calorimeter

  10. APD performance in a luminosity monitor at LEP

    CERN Document Server

    Bartolom, E; Casado, M P; Chmeissani, M; Clemente, S; Fernndez, E; Garrido, L; Lorenz, E; Martnez, M; Merino, G; Riu, I; Snchez, F; Wright, A

    2000-01-01

    Avalanche photo-diodes (APDs) are being used as optical readout elements in a sampling electromagnetic calorimeter made of alternate layers of tungsten and plastic scintillators. The calorimeter serves as a small-angle luminosity monitor in the stray magnetic field of the ALEPH detector at LEP (CERN). Its scintillators are coupled both to APDs and conventional PMTs simultaneously via wavelength shifter fibres. In this paper we present results on the overall performance of the APDs, including gain and stability versus time and energy, based on the direct comparison of the two photosensitive devices. (6 refs).

  11. Bar fraction in lenticular galaxies: dependence on luminosity and environment

    OpenAIRE

    Barway, Sudhanshu; Wadadekar, Yogesh; Kembhavi, Ajit K.

    2010-01-01

    We present a study of bars in lenticular galaxies based on a sample of 371 galaxies from the SDSS-DR 7 and 2MASS in optical and near-infrared bands, respectively. We found a bar in 15% of the lenticular galaxies in our sample, which is consistent with recent studies. The barred galaxy fraction shows a luminosity dependence, with faint lenticular galaxies (MK > -24.5, total absolute magnitude in K band) having a larger fraction of bars than bright lenticular galaxies (MK < -24.5). A similar tr...

  12. The field luminosity function and nearby groups of galaxies

    International Nuclear Information System (INIS)

    A catalog of radial velocities and magnitudes on a homogeneous system (the corrected Harvard, B(o) magnitudes of de Vaucouleurs) has been assembled for over 4000 galaxies. Using this catalog, a magnitude limited sample of approximately 1000 galaxies with nearly complete radial velocity data was compiled. The magnitude limit is 13.0 and the galaxies are primarily from the Shapley-Ames catalog plus a few low and high surface brightness objects properly included in a magnitude limited sample. A new determination of the field luminosity function and density plus initial experiments with the use of a redshift catalog to select groups of galaxies, are briefly described. (Auth.)

  13. Kinetic Luminosity and Composition of Active Galactic Nuclei Jets

    OpenAIRE

    Hirotani, Kouichi

    2004-01-01

    We present a new method how to discriminate the matter content of parsec-scale jets of active galactic nuclei. By constraining the kinetic luminosity of a jet from the observed core size at a single very long baseline interferometry frequency, we can infer the electron density of a radio-emitting component as a function of the composition. Comparing this density with that obtained from the theory of synchrotron self-absorption, we can determine the composition. We apply this procedure to the ...

  14. Prospects for physics at high luminosity with CMS

    Directory of Open Access Journals (Sweden)

    Varela João

    2013-05-01

    Full Text Available The precision measurements of the properties of the recently discovered Higgs-like boson will be central to the future LHC physics program. In parallel the search for New Physics beyond the SM will continue. Higher luminosity will extend the mass reach and allow sensitive searches for possible subtle signatures for new physics. In this paper we review the potential sensitivity of CMS to a selection of relevant future physics scenarios accessible with the LHC upgrades and a correspondingly upgraded CMS detector.

  15. RESULTS FROM LUMINOSITY SCANS DURING THE RHIC 2000 RUN

    International Nuclear Information System (INIS)

    During the year 2000 run a total of eight beam scans (Vernier Scans) were performed at various interaction points (IF) at RHIC. During a Vernier Scan the experimental collision rates are recorded while the beams are stepwise scanned across each other. Vernier Scans yield transverse beam sizes as well as maximum luminosity and thus the absolute cross section, which with the limited data from the 2000 run we measured to be ? = 8.9 0.3 barn at (?sNN) = 130 GeV. Also, Vernier Scans permit performance studies of the beam orbit control and local coupling

  16. Weighing neutrinos using high redshift galaxy luminosity functions

    International Nuclear Information System (INIS)

    We have proposed a novel way to constrain the neutrino mass using UV luminosity function (LF) of high-z Lyman break galaxies. Combining the constraints from the Wilkinson Microwave Anisotropy Probe 7 year (WMAP-7) data with the LF data at z ∼ 4, we have got a limit on the sum of the masses of 3 degenerate neutrinos at the 95 % CL. The additional constraint of using the prior on Hubble constant strengthens this limit to at 95 % CL. As different astronomical measurements may suffer from different set of biases, the method presented here provides a complementary probe of sum of neutrino masses

  17. Operation of the CERN-ISR for high luminosity

    CERN Document Server

    Fischer, C; Lemeilleur, F; Lewis, D; Myers, S; Neet, D; O'Hanlon, H; Risselada, Thys; Vos, L

    1977-01-01

    The CERN intersecting storage rings are routinely operated at 26 GeV/c for physics experiments with proton beam intensities greater than 25 Amps and luminosities greater than 2.10/sup 31/ cm/sup -2/ sec/sup -1 /. Six out of eight intersection regions are used concurrently for colliding beam physics experiments. Each experiment is sensitive to background caused by protons lost from the stacked beams and locally induced radiation. Operational techniques for each of the essential processes involved in establishing stable beam loss rates and the control of background in individual intersections throughout the beam lifetime of about 40 hours are presented. (0 refs).

  18. APD performance in a luminosity monitor at LEP

    International Nuclear Information System (INIS)

    Avalanche Photo-Diodes (APDs) are being used as optical readout elements in a sampling electromagnetic calorimeter made of alternate layers of tungsten and plastic scintillators. The calorimeter serves as a small-angle luminosity monitor in the stray magnetic field of the ALEPH detector at LEP (CERN). Its scintillators are coupled both to APDs and conventional PMTs simultaneously via wavelength shifter fibres. In this paper we present results on the overall performance of the APDs, including gain and stability versus time and energy, based on the direct comparison of the two photosensitive devices

  19. Redshifts of low-X-ray luminosity clusters of galaxies

    Science.gov (United States)

    Kowalski, M. P.; Ulmer, M. P.; Hintzen, P.

    1987-01-01

    Measurements of redshifts and velocity dispersions are presented for Abell clusters A539, A1185, and A1228, and the southern clusters S1840-623, S1904-618, S1908-566, and S2000-561. All these clusters have reported X-ray luminosities or upper limits. Finding charts for the clusters are presented, and the measured heliocentric redshifts are given along with redshifts obtained by other investigators. Comments are made about each cluster. The technique used to derive the redshifts is summarized.

  20. High Luminosity LHC matching section layout vs crab cavity voltage

    CERN Document Server

    Dalena, B; Chance, A; De Maria, R; Fartoukh, S

    2013-01-01

    In the framework of the HiLumi-LHC project we present a new possible variant for the layout of the LHC matching section located in the high luminosity insertions. This layout is optimized to reduce the demand on the voltage of the crab cavities, while substantially improving the optics squeeze-ability, both in ATS [1] and non-ATS mode. This new layout will be described in details together with its performance figures in terms of mechanical acceptance, chromatic properties and optics flexibility.

  1. Galaxies with a Central Minimum in Stellar Luminosity Density

    OpenAIRE

    Lauer, Tod R; Gebhardt, Karl; Richstone, Douglas; Tremaine, Scott; Bender, Ralf; Bower, Gary; Dressler, Alan; Faber, S. M.; Filippenko, Alexei V.; Green, Richard; Grillmair, Carl J.; Ho, Luis C.; Kormendy, John; Magorrian, John; Pinkney, Jason

    2002-01-01

    We used HST WFPC2 images to identify six early-type galaxies with surface- brightness profiles that decrease inward over a limited range of radii near their centers. The implied luminosity density profiles of these galaxies have local minima interior to their core break radii. NGC 3706 harbors a high surface brightness ring of starlight with radius ~20 pc. Its central structure may be related to that in the double-nucleus galaxies M31 and NGC 4486B. NGC 4406 and NGC 6876 have nearly flat core...

  2. Physics potential and experimental challenges of the LHC luminosity upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Gianotti, F.; Ball, A.; Bloch, P.; Casagrande, L.; Cittolin, S.; Roeck, A. de; Ellis, N.; Farthouat, P.; Hansen, J.-B. [CERN, Experimental Physics Division, Geneva (Switzerland); Mangano, M.L. [CERN, Theoretical Physics Division, Geneva (Switzerland); Virdee, T. [CERN, Experimental Physics Division, Geneva (Switzerland); Imperial College, London (United Kingdom); Abdullin, S. [University of Maryland (United States); Azuelos, G. [University of Montreal, Group of Particle Physics, Montreal (Canada); Barberis, D. [Universita di Genova, Dipartimento di Fisica and INFN (Italy); Belyaev, A. [Florida State University, Tallahassee, FL (United States); Bosman, M. [IFAE, Barcelona (Spain); Cavalli, D. [INFN, Milano (Italy); Chumney, P.; Dasu, S. [Univ. of Wisconsin, Madison, WI (United States); Fournier, D. [LAL, Orsay (France); Hinchliffe, I.; Hohlfeld, M.; Huhtinen, M.; Jakobs, K.; Joram, C.; Mazzucato, F.; Mikenberg, G.; Miagkov, A.; Moretti, M.; Moretti, S.; Niinikoski, T.; Nikitenko, A.; Nisati, A.; Paige, F.; Palestini, S.; Papadopoulos, C.G.; Piccinini, F.; Pittau, R.; Polesello, G.; Richter-Was, E.; Sharp, P.; Slabospitsky, S.R.; Smith, W.H.; Stapnes, S.; Tonelli, G.; Tsesmelis, E.; Usubov, Z.; Vacavant, L.; Bij, J. van der; Watson, A.; Wielers, M.

    2004-02-01

    We discuss the physics potential and the experimental challenges of an upgraded LHC running at an instantaneous luminosity of 10{sup 35} cm{sup -2}s{sup -1}. The detector R and D needed to operate ATLAS and CMS in a very high radiation environment and the expected detector performance are discussed. A few examples of the increased physics potential are given, ranging from precise measurements within the Standard Model (in particular in the Higgs sector) to the discovery reach for several New Physics processes. (orig.)

  3. PHOTOMETRIC PROPERTIES AND LUMINOSITY FUNCTION OF NEARBY MASSIVE EARLY-TYPE GALAXIES

    International Nuclear Information System (INIS)

    We perform photometric analyses of a bright early-type galaxy sample with 2949 galaxies (Mr r –2 and 1% of the sky brightness are on average 0.16 mag, 0.20 mag, and 0.26 mag brighter than the SDSS Petrosian values, respectively. In the first case, the underestimations are caused by overestimations in the sky background by the SDSS PHOTO algorithm, while the latter two are also due to deeper photometry. Similarly, the typical half-light radii (r50) measured by the SDSS algorithm are smaller than our measurements. As a result, the bright end of the r-band luminosity function is found to decline more slowly than previous works. Our measured luminosity densities at the bright end are more than one order of magnitude higher than those of Blanton et al., and the stellar mass densities at M* ∼ 5 × 1011 M☉ and M* ∼ 1012 M☉ are a few tenths and a factor of a few higher than those of Bernardi et al. These results may significantly alleviate the tension in the assembly of massive galaxies between observations and predictions of the hierarchical structure formation model

  4. A proposal to upgrade the ATLAS RPC system for the High Luminosity LHC

    CERN Document Server

    ATLAS Collaboration; The ATLAS collaboration

    2015-01-01

    The architecture of the present trigger system in the ATLAS Muon Barrel was designed according to a reference luminosity of 10^34 cm-2 s-1 with a safety factor of 5, with respect to the simulated background rates, now confirmed by LHC Run-1 data. HL-LHC will provide a luminosity 5 times higher and an order of magnitude higher background. As a result, the performance demand increases, while the detector being susceptible to ageing effects. Moreover, the present muon trigger acceptance in the barrel is just above 70%, due to the presence of the barrel toroid structures. This scenario induced the ATLAS muon Collaboration to propose an appropriate upgrade plan, involving both detector and trigger-readout electronics, to guarantee the performance required by the physics program for the 20 years scheduled. This consists in installing a layer of new generation RPCs in the inner barrel, to increase the redundancy, the selectivity, and provide almost full acceptance. The first 10% of the system, corresponding to the e...

  5. High Luminosity Large Hadron Collider A description for the European Strategy Preparatory Group

    CERN Document Server

    Rossi, L

    2012-01-01

    The Large Hadron Collider (LHC) is the largest scientific instrument ever built. It has been exploring the new energy frontier since 2009, gathering a global user community of 7,000 scientists. It will remain the most powerful accelerator in the world for at least two decades, and its full exploitation is the highest priority in the European Strategy for Particle Physics, adopted by the CERN Council and integrated into the ESFRI Roadmap. To extend its discovery potential, the LHC will need a major upgrade around 2020 to increase its luminosity (rate of collisions) by a factor of 10 beyond its design value. As a highly complex and optimized machine, such an upgrade of the LHC must be carefully studied and requires about 10 years to implement. The novel machine configuration, called High Luminosity LHC (HL-LHC), will rely on a number of key innovative technologies, representing exceptional technological challenges, such as cutting-edge 13 tesla superconducting magnets, very compact and ultra-precise superconduc...

  6. The luminosity function of the brightest galaxies in the IRAS survey

    Science.gov (United States)

    Soifer, B. T.; Sanders, D. B.; Madore, B. F.; Neugebauer, G.; Persson, C. J.; Persson, S. E.; Rice, W. L.

    1987-01-01

    Results from a study of the far infrared properties of the brightest galaxies in the IRAS survey are described. There is a correlation between the infrared luminosity and the infrared to optical luminosity ratio and between the infrared luminosity and the far infrared color temperature in these galaxies. The infrared bright galaxies represent a significant component of extragalactic objects in the local universe, being comparable in space density to the Seyferts, optically identified starburst galaxies, and more numerous than quasars at the same bolometric luminosity. The far infrared luminosity in the local universe is approximately 25% of the starlight output in the same volume.

  7. Luminosity determination at ANKE with different reference reactions

    Energy Technology Data Exchange (ETDEWEB)

    Fritzsch, Christopher; Goslawski, Paul; Mielke, Malte; Papenbrock, Michael; Schroeer, Daniel; Taeschner, Alexander; Khoukaz, Alfons [Muenster Univ. (Germany). Inst. fuer Kernphysik

    2013-07-01

    A high precision measurement on the mass of the eta meson was the main objective of the COSY proposal Nr. 187. In detail the meson production reaction dp → {sup 3}HeX has been studied with X being the eta meson identified by the missing mass technique. However, parallel to the already very successfully performed eta mass determination, the obtained data also allow for studies on total and differential cross sections for the reaction dp → {sup 3}Heη close to threshold as well as for a study of the ABC-effect in the channel dp → {sup 3}Heπ{sup +}π{sup -}. For this purpose a careful data normalization and luminosity determination is required. While dp-elastic scattering is commonly used as reference reaction for the luminosity determination at ANKE, an independent normalization channel is of high interest as cross reference. Therefore, the {sup 3}Heπ{sup 0} final state is analyzed in parallel and the results are compared to the dp-elastic scattering data. The method and recent results are presented.

  8. Radio and optical studies of high luminosity Iras galaxies

    International Nuclear Information System (INIS)

    Follow-up observations of a complete sample of 154 IRAS galaxies, optically identified down to B=21, indicate that between 3 and 9% of the sample are ultraluminous depending on the choice of H0. VLA observations at 20 cm of the complete sample indicate that 85% are detected above 1mJy and for the most part the radio emission is centrally concentrated. The tight linear relation between radio and infrared luminosities is valid at the highest luminosities. Of the 11 most luminous objects one is a quasar: it fits the radio infrared relation very well which suggests that the infrared and radio emission has the same origin as in the other IRAS galaxies, ie. it probably originates primarily in regions of star formation in the host galaxy. The other 10 very luminous galaxies are either close but resolved mergers or double galaxies, presumably interacting. Radio observations of the 10 original empty field sources in our sample with no optical counterpart (B ≤ 21) allow us to conclude that 4 of these are fainter galaxies just outside the IRAS error ellipse with high values of LIR/LB. One other object, with a radio source at the edge of the error ellipse but no optical counterpart brighter than B = 23, may prove to be a highly luminous galaxy with LIR/LB > ∼ 1250

  9. ATLAS Muon Spectrometer Upgrades for the High Luminosity LHC

    CERN Document Server

    Valderanis, Chrysostomos; The ATLAS collaboration

    2015-01-01

    ATLAS Muon Spectrometer Upgrades for the High Luminosity LHC The luminosity of the LHC will increase up to 2x10^34 cm-2s-1 after the long shutdown in 2019 (phase-1 upgrade) and up to 7x10^34 cm-2s-1 after the long shutdown in 2025 (phase-2 upgrade). In order to cope with the increased particle fluxes, upgrades are envisioned for the ATLAS muon spectrometer. At phase-1, the current innermost stations of the ATLAS muon endcap tracking system (the Small Wheels) will be upgraded with 2x4-layer modules of Micromega detectors, sandwiched by two 4 layer modules of small strip Thin Gap Chambers on either side. Each 4-layer module of the so-called New Small Wheels covers a surface area of approximately 2 to 3 m2 for a total active area of 1200 m2 each for the two technologies. On such large area detectors, the mechanical precision (30 \\mu m along the precision coordinate and 80 \\mu m along the beam) is a key point and must be controlled and monitored along the process of construction and integration. The design and re...

  10. The Galaxy UV Luminosity Function Before the Epoch of Reionization

    CERN Document Server

    Mason, Charlotte; Treu, Tommaso

    2015-01-01

    We present a model for the evolution of the galaxy ultraviolet (UV) luminosity function (LF) across cosmic time where star formation is linked to the assembly of dark matter halos under the assumption of a halo mass dependent, but redshift independent, star formation efficiency. This model improves on previous work by introducing a new self-consistent treatment of the halo star formation history, which allows us to make predictions at redshift $z>10$ (lookback time $\\lesssim500$ Myr), when growth is rapid. With a calibration at a single redshift to set the stellar to halo mass ratio, and no further degrees of freedom, our model captures the evolution of the UV LF over all the available observations ($0\\lesssim z\\lesssim10$). The significant drop in the luminosity density of currently detectable galaxies beyond $z\\sim8$ is explained by a shift of star formation toward less massive, fainter galaxies. Assuming that star formation proceeds down to atomic cooling halos, we derive a reionization optical depth $\\tau...

  11. Revisiting the luminosity function of single halo white dwarfs

    CERN Document Server

    Cojocaru, R; Althaus, L G; Isern, J; García-Berro, E

    2015-01-01

    White dwarfs are the fossils left by the evolution of low-and intermediate-mass stars, and have very long evolutionary timescales. This allows us to use them to explore the properties of old populations, like the Galactic halo. We present a population synthesis study of the luminosity function of halo white dwarfs, aimed at investigating which information can be derived from the currently available observed data. We employ an up-to-date population synthesis code based on Monte Carlo techniques, that incorporates the most recent and reliable cooling sequences for metal poor progenitors as well as an accurate modeling of the observational biases. We find that because the observed sample of halo white dwarfs is restricted to the brightest stars only the hot branch of the white dwarf luminosity function can be used for such purposes, and that its shape function is almost insensitive to the most relevant inputs, like the adopted cooling sequences, the initial mass function, the density profile of the stellar spher...

  12. High luminosity electron-hadron collider eRHIC

    Energy Technology Data Exchange (ETDEWEB)

    Ptitsyn, V.; Aschenauer, E.; Bai, M.; Beebe-Wang, J.; Belomestnykh, S.; Ben-Zvi, I.; Blaskiewicz, M..; Calaga, R.; Chang, X.; Fedotov, A.; Gassner, D.; Hammons, L.; Hahn, H.; Hammons, L.; He, P.; Hao, Y.; Jackson, W.; Jain, A.; Johnson, E.C.; Kayran, D.; Kewisch, J.; Litvinenko, V.N.; Luo, Y.; Mahler, G.; McIntyre, G.; Meng, W.; Minty, M.; Parker, B.; Pikin, A.; Rao, T.; Roser, T.; Skaritka, J.; Sheehy, B.; Skaritka, J.; Tepikian, S.; Than, Y.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J.; Wang, G.; Webb, S.; Wu, Q.; Xu, W.; Pozdeyev, E.; Tsentalovich, E.

    2011-03-28

    We present the design of a future high-energy high-luminosity electron-hadron collider at RHIC called eRHIC. We plan on adding 20 (potentially 30) GeV energy recovery linacs to accelerate and to collide polarized and unpolarized electrons with hadrons in RHIC. The center-of-mass energy of eRHIC will range from 30 to 200 GeV. The luminosity exceeding 10{sup 34} cm{sup -2} s{sup -1} can be achieved in eRHIC using the low-beta interaction region with a 10 mrad crab crossing. We report on the progress of important eRHIC R&D such as the high-current polarized electron source, the coherent electron cooling, ERL test facility and the compact magnets for recirculation passes. A natural staging scenario of step-by-step increases of the electron beam energy by building-up of eRHIC's SRF linacs is presented.

  13. Optical variability properties of high luminosity AGN classes

    CERN Document Server

    Stalin, C S; Wiita, P J; Sagar, Ram; Wiita, Paul J.

    2003-01-01

    We present the results of a comparative study of the intra-night optical variability (INOV) characteristics of radio-loud and radio-quiet quasars, which involves a systematic intra-night optical monitoring of seven sets of high luminosity AGNs covering the redshift range {it z} $simeq 0.2$ to {it z} $simeq 2.2$. The sample, matched in the optical luminosity -- redshift (M$_B$ -- z) plane, consists of seven radio-quiet quasars (RQQs), eight radio lobe-dominated quasars (LDQs), six radio core-dominated quasars (CDQs) and five BL Lac objects (BLs). Systematic CCD observations, aided by a careful data analysis procedure, have allowed us to detect INOV with amplitudes as low as 1%. Present observations cover a total of 113 nights (720 hours) with only a single quasar monitored as continuously as possible on a night. Considering cases of only unambiguous detections of INOV we have estimated duty cycles (DCs) of 17%, 12%, 20% and 72% respectively for RQQs, LDQs, CDQs, and BLs. The low amplitude and low DC of INOV sh...

  14. Radio variability survey of very low luminosity protostars

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Minho; Kang, Miju [Korea Astronomy and Space Science Institute, 776 Daedeokdaero, Daejeon 305-348 (Korea, Republic of); Lee, Jeong-Eun, E-mail: minho@kasi.re.kr [Department of Astronomy and Space Science, Kyung Hee University, Yongin, Gyeonggi 446-701 (Korea, Republic of)

    2014-07-01

    Ten very low luminosity objects were observed multiple times in the 8.5 GHz continuum in search of protostellar magnetic activities. A radio outburst of IRAM 04191+1522 IRS was detected, and the variability timescale was about 20 days or shorter. The results of this survey and archival observations suggest that IRAM 04191+1522 IRS is in active states about half the time. Archival data show that L1014 IRS and L1148 IRS were detectable previously and suggest that at least 20%-30% of very low luminosity protostars are radio variables. Considering the variability timescale and flux level of IRAM 04191+1522 IRS and the previous detection of the circular polarization of L1014 IRS, the radio outbursts of these protostars are probably caused by magnetic flares. However, IRAM 04191+1522 IRS is too young and small to develop an internal convective dynamo. If the detected radio emission is indeed coming from magnetic flares, the discovery implies that the flares may be caused by the fossil magnetic fields of interstellar origin.

  15. SDSS Galaxy Clustering: Luminosity & Color Dependence and Stochasticity

    CERN Document Server

    Swanson, M E C; Blanton, M; Zehavi, I; Swanson, Molly E.C.; Tegmark, Max; Blanton, Michael; Zehavi, Idit

    2007-01-01

    Differences in clustering properties between galaxy subpopulations complicate the cosmological interpretation of the galaxy power spectrum, but can also provide insights about the physics underlying galaxy formation. To study the nature of this relative clustering, we perform a counts-in-cells analysis of galaxies in the Sloan Digital Sky Survey (SDSS) in which we measure the relative bias between pairs of galaxy subsamples of different luminosities and colors. We use a generalized chi-squared test to determine if the relative bias between each pair of subsamples is consistent with the simplest deterministic linear bias model, and we also use a maximum likelihood technique to further understand the nature of the relative bias between each pair. We find that the simple, deterministic model is a good fit for the luminosity-dependent bias on scales above about 5 Mpc/h, which is good news for using magnitude-limited surveys for cosmology. However, the color-dependent bias shows evidence for stochasticity and/or n...

  16. Differential Density Statistics of Galaxy Distribution and the Luminosity Function

    CERN Document Server

    Albani, V V L; Ribeiro, M B; Stöger, W R; Albani, Vinicius V. L.; Iribarrem, Alvaro S.; Ribeiro, Marcelo B.; Stoeger, William R.

    2006-01-01

    This paper uses data obtained from the galaxy luminosity function (LF) to calculate two types of radial number densities statistics of the galaxy distribution as discussed in Ribeiro (2005), namely the differential density $\\gamma$ and the integral differential density $\\gamma^\\ast$. By applying the theory advanced by Ribeiro and Stoeger (2003), which connects the relativistic cosmology number counts with the astronomically derived LF, the differential number counts $dN/dz$ are extracted from the LF and used to calculate both $\\gamma$ and $\\gamma^\\ast$ with various cosmological distance definitions, namely the area distance, luminosity distance, galaxy area distance and redshift distance. LF data are taken from the CNOC2 galaxy redshift survey and $\\gamma$ and $\\gamma^\\ast$ are calculated for two cosmological models: Einstein-de Sitter and an $\\Omega_{m_0}=0.3$, $\\Omega_{\\Lambda_0}=0.7$ standard cosmology. The results confirm the strong dependency of both statistics on the distance definition, as predicted in...

  17. Relativistic Cosmology Number Densities and the Luminosity Function

    CERN Document Server

    Iribarrem, Alvaro S; Ribeiro, Marcelo B; Stoeger, William R

    2012-01-01

    This paper studies the connection between the relativistic number density of galaxies down the past light cone in a Friedmann-Lemaitre-Robertson-Walker spacetime with non-vanishing cosmological constant and the galaxy luminosity function (LF) data. It extends the redshift range of previous results presented in Albani et al. (2007, arXiv:astro-ph/0611032) where the galaxy distribution was studied out to z=1. Observational inhomogeneities were detected at this range. This research also searches for LF evolution in the context of the framework advanced by Ribeiro and Stoeger (2003, arXiv:astro-ph/0304094), further developing the theory linking relativistic cosmology theory and LF data. Selection functions are obtained using the Schechter parameters and redshift parametrization of the galaxy luminosity functions obtained from an I-band selected dataset of the FORS Deep Field galaxy survey in the redshift range 0.5

  18. Luminosity Indicators in the UV Spectra of Type Ia Supernovae

    CERN Document Server

    Foley, Ryan J; Jha, Saurabh W

    2008-01-01

    We present a complete sample of International Ultraviolet Explorer and Hubble Space Telescope ultraviolet (UV) spectra of Type Ia supernovae (SNe Ia) through 2004. We measure the equivalent width (EW) and blueshifted velocity of the minimum of the one strong UV feature, Fe II 3250. We also quantify the slope of the near-UV spectra using a new parameter, the ``UV ratio.'' We find that the velocity of the Fe II line does not correlate with light-curve shape, while the EW shows distinct behavior for the slow and fast-declining objects. Using precise Cepheid and surface brightness fluctuation distance measurements of 6 objects with UV spectra observed near maximum light (a total of 12 spectra), we determine that the UV ratio at maximum light is highly correlated with SN Ia luminosity. A larger sample of UV spectra is necessary to increase the statistical certainty of these luminosity indicators and whether they can be combined with light-curve shape to improve measured SN Ia distances.

  19. The dynamical state of galaxy groups and their luminosity content

    CERN Document Server

    Martinez, Hector J

    2011-01-01

    We analyse the dependence of the luminosity function of galaxies in groups (LF) on group dynamical state. We use the Gaussianity of the velocity distribution of galaxy members as a measurement of the dynamical equilibrium of groups identified in the SDSS Data Release 7 by Zandivarez & Martinez. We apply the Anderson-Darling goodness-of-fit test to distinguish between groups according to whether they have Gaussian or Non-Gaussian velocity distributions, i.e., whether they are relaxed or not. For these two subsamples, we compute the $^{0.1}r-$band LF as a function of group virial mass and group total luminosity. For massive groups, ${\\mathcal M}>5 \\times 10^{13} \\ M_{\\odot} \\ h^{-1}$, we find statistically significant differences between the LF of the two subsamples: the LF of groups that have Gaussian velocity distributions have a brighter characteristic absolute magnitude ($\\sim0.3$ mag) and a steeper faint end slope ($\\sim0.25$). We detect a similar effect when comparing the LF of bright ($M^{group}_{^{0...

  20. Disk Outflows and High-Luminosity True Type 2 AGN

    CERN Document Server

    Elitzur, Moshe

    2016-01-01

    The absence of intrinsic broad line emission has been reported in a number of active galactic nuclei (AGN), including some with high Eddington ratios. Such "true type 2 AGN" are inherent to the disk-wind scenario for the broad line region: Broad line emission requires a minimal column density, implying a minimal outflow rate and thus a minimal accretion rate. Here we perform a detailed analysis of the consequences of mass conservation in the process of accretion through a central disk. The resulting constraints on luminosity are consistent with all the cases where claimed detections of true type 2 AGN pass stringent criteria, and predict that intrinsic broad line emission can disappear at luminosities as high as about 4x$10^{46}$ erg s$^{-1}$ and any Eddington ratio, though more detections can be expected at Eddington ratios below about 1%. Our results are applicable to every disk outflow model, whatever its details and whether clumpy or smooth, irrespective of the wind structure and its underlying dynamics. ...

  1. Low-luminosity Active Galaxies and their Central Black Holes

    CERN Document Server

    Dong, X; Dong, Xiaoyi; Robertis, Michael M. De

    2005-01-01

    Central black hole masses for 118 spiral galaxies representing morphological stages S0/a through Sc and taken from the large spectroscopic survey of Ho, Filippenko & Sargent (1997) are derived using 2MASS Ks data. Black hole (BH) masses are found using a calibrated black-hole - Ks bulge luminosity relation, while bulge luminosities are measured using GALFIT, a two-dimensional bulge/disk decomposition routine. The BH masses are correlated against a variety of nuclear and host-galaxy properties. Nuclear properties such as line width and line ratios show a very high degree of correlation with BH mass. The excellent correlation with line-width supports the view that the emission-line gas is in virial equilibrium with either the BH or bulge potential. The very good emission-line ratio correlations may indicate a change in ionizing continuum shape with BH mass in the sense that more massive BHs generate harder spectra. Apart from the inclination-corrected rotational velocity, no excellent correlations are found...

  2. Absolute luminosity measurements with the LHCb detector at the LHC

    CERN Document Server

    Aaij, R; Adinolfi, M; Adrover, C; Affolder, A; Ajaltouni, Z; Albrecht, J; Alessio, F; Alexander, M; Alkhazov, G; Alvarez Cartelle, P; Alves, A A; Amato, S; Amhis, Y; Anderson, J; Appleby, R B; Aquines Gutierrez, O; Archilli, F; Arrabito, L; Artamonov, A; Artuso, M; Aslanides, E; Auriemma, G; Bachmann, S; Back, J J; Bailey, D S; Balagura, V; Baldini, W; Barlow, R J; Barschel, C; Barsuk, S; Barter, W; Bates, A; Bauer, C; Bauer, Th; Bay, A; Bediaga, I; Belous, K; Belyaev, I; Ben-Haim, E; Benayoun, M; Bencivenni, G; Benson, S; Benton, J; Bernet, R; Bettler, M-O; van Beuzekom, M; Bien, A; Bifani, S; Bizzeti, A; Bjrnstad, P M; Blake, T; Blanc, F; Blanks, C; Blouw, J; Blusk, S; Bobrov, A; Bocci, V; Bondar, A; Bondar, N; Bonivento, W; Borghi, S; Borgia, A; Bowcock, T J V; Bozzi, C; Brambach, T; van den Brand, J; Bressieux, J; Brett, D; Brisbane, S; Britsch, M; Britton, T; Brook, N H; Brown, H; Bchler-Germann, A; Burducea, I; Bursche, A; Buytaert, J; Cadeddu, S; Caicedo Carvajal, J M; Callot, O; Calvi, M; Calvo Gomez, M; Camboni, A; Campana, P; Carbone, A; Carboni, G; Cardinale, R; Cardini, A; Carson, L; Carvalho Akiba, K; Casse, G; Cattaneo, M; Charles, M; Charpentier, Ph; Chiapolini, N; Ciba, K; Cid Vidal, X; Ciezarek, G; Clarke, P E L; Clemencic, M; Cliff, H V; Closier, J; Coca, C; Coco, V; Cogan, J; Collins, P; Constantin, F; Conti, G; Contu, A; Cook, A; Coombes, M; Corti, G; Cowan, G A; Currie, R; D'Almagne, B; D'Ambrosio, C; David, P; De Bonis, I; De Capua, S; De Cian, M; De Lorenzi, F; De Miranda, J M; De Paula, L; De Simone, P; Decamp, D; Deckenhoff, M; Degaudenzi, H; Deissenroth, M; Del Buono, L; Deplano, C; Deschamps, O; Dettori, F; Dickens, J; Dijkstra, H; Diniz Batista, P; Donleavy, S; Dordei, F; Dosil Surez, A; Dossett, D; Dovbnya, A; Dupertuis, F; Dzhelyadin, R; Eames, C; Easo, S; Egede, U; Egorychev, V; Eidelman, S; van Eijk, D; Eisele, F; Eisenhardt, S; Ekelhof, R; Eklund, L; Elsasser, Ch; d'Enterria, D G; Esperante Pereira, D; Estve, L; Falabella, A; Fanchini, E; Frber, C; Fardell, G; Farinelli, C; Farry, S; Fave, V; Fernandez Albor, V; Ferro-Luzzi, M; Filippov, S; Fitzpatrick, C; Fontana, M; Fontanelli, F; Forty, R; Frank, M; Frei, C; Frosini, M; Furcas, S; Gallas Torreira, A; Galli, D; Gandelman, M; Gandini, P; Gao, Y; Garnier, J-C; Garofoli, J; Garra Tico, J; Garrido, L; Gaspar, C; Gauvin, N; Gersabeck, M; Gershon, T; Ghez, Ph; Gibson, V; Gligorov, V V; Gbel, C; Golubkov, D; Golutvin, A; Gomes, A; Gordon, H; Grabalosa Gndara, M; Graciani Diaz, R; Granado Cardoso, L A; Graugs, E; Graziani, G; Grecu, A; Gregson, S; Gui, B; Gushchin, E; Guz, Yu; Gys, T; Haefeli, G; Haen, C; Haines, S C; Hampson, T; Hansmann-Menzemer, S; Harji, R; Harnew, N; Harrison, J; Harrison, P F; He, J; Heijne, V; Hennessy, K; Henrard, P; Hernando Morata, J A; van Herwijnen, E; Hicks, E; Hofmann, W; Holubyev, K; Hopchev, P; Hulsbergen, W; Hunt, P; Huse, T; Huston, R S; Hutchcroft, D; Hynds, D; Iakovenko, V; Ilten, P; Imong, J; Jacobsson, R; Jaeger, A; Jahjah Hussein, M; Jans, E; Jansen, F; Jaton, P; Jean-Marie, B; Jing, F; John, M; Johnson, D; Jones, C R; Jost, B; Kandybei, S; Karacson, M; Karbach, T M; Keaveney, J; Kerzel, U; Ketel, T; Keune, A; Khanji, B; Kim, Y M; Knecht, M; Koblitz, S; Koppenburg, P; Kozlinskiy, A; Kravchuk, L; Kreplin, K; Kreps, M; Krocker, G; Krokovny, P; Kruse, F; Kruzelecki, K; Kucharczyk, M; Kukulak, S; Kumar, R; Kvaratskheliya, T; La Thi, V N; Lacarrere, D; Lafferty, G; Lai, A; Lambert, D; Lambert, R W; Lanciotti, E; Lanfranchi, G; Langenbruch, C; Latham, T; Le Gac, R; van Leerdam, J; Lees, J-P; Lefvre, R; Leflat, A; Lefranois, J; Leroy, O; Lesiak, T; Li, L; Li Gioi, L; Lieng, M; Liles, M; Lindner, R; Linn, C; Liu, B; Liu, G; Lopes, J H; Lopez Asamar, E; Lopez-March, N; Luisier, J; Machefert, F; Machikhiliyan, I V; Maciuc, F; Maev, O; Magnin, J; Malde, S; Mamunur, R M D; Manca, G; Mancinelli, G; Mangiafave, N; Marconi, U; Mrki, R; Marks, J; Martellotti, G; Martens, A; Martin, L; Martn Snchez, A; Martinez Santos, D; Massafferri, A; Matev, R; Mathe, Z; Matteuzzi, C; Matveev, M; Maurice, E; Maynard, B; Mazurov, A; McGregor, G; McNulty, R; Mclean, C; Meissner, M; Merk, M; Merkel, J; Messi, R; Miglioranzi, S; Milanes, D A; Minard, M-N; Monteil, S; Moran, D; Morawski, P; Mountain, R; Mous, I; Muheim, F; Mller, K; Muresan, R; Muryn, B; Musy, M; Mylroie-Smith, J; Naik, P; Nakada, T; Nandakumar, R; Nardulli, J; Nasteva, I; Nedos, M; Needham, M; Neufeld, N; Nguyen-Mau, C; Nicol, M; Nies, S; Niess, V; Nikitin, N; Oblakowska-Mucha, A; Obraztsov, V; Oggero, S; Ogilvy, S; Okhrimenko, O; Oldeman, R; Orlandea, M; Otalora Goicochea, J M; Owen, P; Pal, B; Palacios, J; Palutan, M; Panman, J; Papanestis, A; Pappagallo, M; Parkes, C; Parkinson, C J; Passaleva, G; Patel, G D; Patel, M; Paterson, S K; Patrick, G N; Patrignani, C; Pavel-Nicorescu, C

    2012-01-01

    Absolute luminosity measurements are of general interest for colliding-beam experiments at storage rings. These measurements are necessary to determine the absolute cross-sections of reaction processes and are valuable to quantify the performance of the accelerator. LHCb has applied two methods to determine the absolute scale of its luminosity measurements for proton-proton collisions at the LHC with a centre-of-mass energy of 7 TeV. In addition to the classic ``van der Meer scan'' method a novel technique has been developed which makes use of direct imaging of the individual beams using beam-gas and beam-beam interactions. This beam imaging method is made possible by the high resolution of the LHCb vertex detector and the close proximity of the detector to the beams, and allows beam parameters such as positions, angles and widths to be determined. The results of the two methods have comparable precision and are in good agreement. Combining the two methods, an overall precision of 3.5\\% in the absolute lumi...

  3. Topological and Central Trigger Processor for 2014 LHC luminosities

    CERN Document Server

    Simioni, E; The ATLAS collaboration; Bauss, B; Berge, D; B\\"{u}scher, V; Childers, T; Degele, R; Dobson, E; Ebling, A; Ellis, N; Farthouat, P; Gabaldon, C; Gorini, B; Haas, S; Ji, W; Kaneda, M; M\\"{a}ttig, S; Messina, A; Meyer, C; Moritz, S; Pauly, T; Pottgen, R; Sch\\"{a}fer, U; Spiwoks, R; Tapprogge, S; Wengler, T; Wenzel, V

    2012-01-01

    The ATLAS experiment is located at the European Center for Nu- clear Research (CERN) in Switzerland. It is designed to observe phe- nomena that involve highly massive particles produced in the collisions at the Large Hadron Collider (LHC): the world’s largest and highest-energy particle accelerator. Event triggering and Data Acquisition is one of the extraordinary challenges faced by the detectors at the high luminosity LHC collider. During 2011, the LHC reached instantaneous luminosities of 4×10^33 cm−1 s−1 and produced events with up to 24 interactions per colliding proton bunch. This places stringent operational and physical requirements on the AT- LAS Trigger in order to reduce the 40MHz collision rate to a manageable event storage rate of 400Hz and, at the same time, selecting those events considered interesting. The Level-1 Trigger is the first rate-reducing step in the ATLAS Trigger, with an output rate of 75kHz and decision latency of less than 2.5μs. It is primarily composed of the Calorimete...

  4. Low extreme-ultraviolet luminosities impinging on protoplanetary disks

    Energy Technology Data Exchange (ETDEWEB)

    Pascucci, I.; Hendler, N. P. [Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ 85721 (United States); Ricci, L. [Department of Astronomy, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Gorti, U.; Hollenbach, D. [SETI Institute, 189 Bernardo Ave., Mountain View, CA 94043 (United States); Brooks, K. J.; Contreras, Y., E-mail: pascucci@lpl.arizona.edu [Australia Telescope National Facility, P.O. Box 76, Epping, NSW 1710 (Australia)

    2014-11-01

    The amount of high-energy stellar radiation reaching the surface of protoplanetary disks is essential to determine their chemistry and physical evolution. Here, we use millimetric and centimetric radio data to constrain the extreme-ultraviolet (EUV) luminosity impinging on 14 disks around young (∼2-10 Myr) sun-like stars. For each object we identify the long-wavelength emission in excess to the dust thermal emission, attribute that to free-free disk emission, and thereby compute an upper limit to the EUV reaching the disk. We find upper limits lower than 10{sup 42} photons s{sup –1} for all sources without jets and lower than 5 × 10{sup 40} photons s{sup –1} for the three older sources in our sample. These latter values are low for EUV-driven photoevaporation alone to clear out protoplanetary material in the timescale inferred by observations. In addition, our EUV upper limits are too low to reproduce the [Ne II] 12.81 μm luminosities from three disks with slow [Ne II]-detected winds. This indicates that the [Ne II] line in these sources primarily traces a mostly neutral wind where Ne is ionized by 1 keV X-ray photons, implying higher photoevaporative mass loss rates than those predicted by EUV-driven models alone. In summary, our results suggest that high-energy stellar photons other than EUV may dominate the dispersal of protoplanetary disks around sun-like stars.

  5. Low extreme-ultraviolet luminosities impinging on protoplanetary disks

    International Nuclear Information System (INIS)

    The amount of high-energy stellar radiation reaching the surface of protoplanetary disks is essential to determine their chemistry and physical evolution. Here, we use millimetric and centimetric radio data to constrain the extreme-ultraviolet (EUV) luminosity impinging on 14 disks around young (∼2-10 Myr) sun-like stars. For each object we identify the long-wavelength emission in excess to the dust thermal emission, attribute that to free-free disk emission, and thereby compute an upper limit to the EUV reaching the disk. We find upper limits lower than 1042 photons s–1 for all sources without jets and lower than 5 × 1040 photons s–1 for the three older sources in our sample. These latter values are low for EUV-driven photoevaporation alone to clear out protoplanetary material in the timescale inferred by observations. In addition, our EUV upper limits are too low to reproduce the [Ne II] 12.81 μm luminosities from three disks with slow [Ne II]-detected winds. This indicates that the [Ne II] line in these sources primarily traces a mostly neutral wind where Ne is ionized by 1 keV X-ray photons, implying higher photoevaporative mass loss rates than those predicted by EUV-driven models alone. In summary, our results suggest that high-energy stellar photons other than EUV may dominate the dispersal of protoplanetary disks around sun-like stars.

  6. LHC Report: spring cleaning over, bunches of luminosity

    CERN Multimedia

    CERN Bulletin

    2011-01-01

    Scrubbing was completed on Wednesday 13 April. The run had seen over 1000 bunches per beam successfully circulating at 450 GeV. Measurements showed that electron cloud activity in the cold regions had been suppressed. A decrease of vacuum activity in the warm regions demonstrated that the cleaning had also achieved the required results there. As discussed in the last Bulletin, the scrubbing was performed with high intensity bunches with 50 nanosecond spacing. Given the potential luminosity performance with this spacing (more bunches, higher bunch intensity from the injectors) and in the light of the results of the scrubbing run, the decision was taken to continue the 2011 physics run with this bunch spacing.   A few issues with 50 nanosecond spacing had to be resolved when standard operations for luminosity production resumed. Once things had been tidied up, stable beams were provided for the experiments, firstly with 228 bunches per beam and then with 336 bunches per beam. The 336 bunch fill that w...

  7. Luminosity and tune shift in e+e- storage rings

    International Nuclear Information System (INIS)

    Luminosity and tune shift have been the subject of numerous papers and talks since the invention of electron-positron storage rings. This paper derives an equation for luminosity and one for the linear tune shift based upon two simple assumptions. The first assumption is that the storage ring be designed such that the linear tune shifts in the two transverse planes, x and y, are equal; i.e., that ?nu/sub x/ = ?nu/sub y/. The second assumption is that the maximum acceptable disruption angle, ?/sub D/, of the colliding beams is approximately equal to the ''natural'' beam spread, ?/sub B/, of the stored colliding beams at the interaction point. First derived is the results for round beams having transverse gaussian distribution functions and then extend the derivation to beams having elliptical cross sections. Then compared are theoretical results with the observed results in several operating machines and with the ''design'' parameters of three new machines; namely KEK, BEPC, and LEP

  8. Extra-galactic high-energy transients: event rate densities and luminosity functions

    CERN Document Server

    Sun, Hui; Li, Zhuo

    2015-01-01

    Several types of extra-galactic high-energy transients have been discovered, which include high-luminosity and low-luminosity long-duration gamma-ray bursts (GRBs), short-duration GRBs, supernova shock breakouts (SBOs), and tidal disruption events (TDEs) without or with an associated relativistic jet. In this paper, we apply a unified method to systematically study the redshift-dependent event rate densities and the global luminosity functions (ignoring redshift evolution) of these transients. We introduce some empirical formulae for the redshift-dependent event rate densities for different types of transients, and derive the local specific event rate density, which also represents its global luminosity function. Long GRBs have a large enough sample to reveal features in the global luminosity function, which is best characterized as a triple power law. All the other transients are consistent with having a single power law luminosity function. The total event rate density depends on the minimum luminosity, and...

  9. Does nest luminosity play a role in recognition of parasitic eggs in domed nests? A case study of the red bishop

    Czech Academy of Sciences Publication Activity Database

    Honza, Marcel; Šulc, Michal; Cherry, M. I.

    2014-01-01

    Roč. 101, č. 12 (2014), s. 1009-1015. ISSN 0028-1042 Institutional support: RVO:68081766 Keywords : Brood parasitism * Domed nest * Egg discrimination * Light conditions * Nest luminosity Subject RIV: EG - Zoology Impact factor: 2.098, year: 2014

  10. High luminosity IRAS galaxies - I. The proportion of IRAS galaxies in interacting systems

    International Nuclear Information System (INIS)

    We report CCD imaging of a complete sample of 60 high-luminosity IRAS galaxies and of a control sample of 87 optically selected galaxies. The galaxies have been grouped in seven classes depending on the presence or absence of faint or bright, nearby or distant, companions, and signs of interaction or mergers such as tidal arms or disturbed structure. We find that 185 per cent of optically selected galaxies are in interacting or merging systems. The excess of interacting pairs over those which we would expect to find by chance is about 30 per cent. Many of the pairs are unresolved by the IRAS beam, but we demonstrate that this cannot explain the enhanced fraction of pairs. These results indicate that galaxy interaction is a common causal factor in luminous IR activity. (author)

  11. Levitating atmospheres of Eddington-luminosity neutron stars

    Science.gov (United States)

    Wielgus, Maciek; Sądowski, Aleksander; Kluźniak, Włodek; Abramowicz, Marek; Narayan, Ramesh

    2016-03-01

    We construct models of static, spherically symmetric shells supported by the radiation flux of a luminous neutron star in the Schwarzschild metric. The atmospheres are disconnected from the star and levitate above its surface. Gas pressure and density inversion appear in the inner region of these atmospheres, which is a purely relativistic phenomenon. We account for the scattering opacity dependence on temperature green by using the Klein-Nishina formula. The relativistic M1 closure scheme for the radiation tensor provides a GR-consistent treatment of the photon flux and radiation tensor anisotropy. In this way we are able to address atmospheres of both large and moderate/low optical depths with the same set of equations. We discuss properties of the levitating atmospheres and find that they may indeed be optically thick, with the distance between star surface and the photosphere expanding as luminosity increases. These results may be relevant for the photosphereric radius expansion X-ray bursts.

  12. NGC 5548 in a Low-Luminosity State

    DEFF Research Database (Denmark)

    Bentz, Misty C.; Denney, Kelly D.; Cackett, Edward M.; Dietrich, Matthias; Fogel, Jeffrey K. J.; Ghosh, Himel; Horne, Keith D.; Kuehn, Charles; Minezaki, Takeo; Onken, Christopher A.; Peterson, Bradley M.; Pogge, Richard W.; Pronik, Vladimir I.; Richstone, Douglas O.; Sergeev, Sergey G.; Vestergaard, Marianne; Walker, Matthew G.; Yoshii, Yuzuru

    2007-01-01

    We describe results from a new ground-based monitoring campaign on NGC 5548, the best studied reverberation-mapped AGN. We find that it was in the lowest luminosity state yet recorded during a monitoring program, namely L(5100) = 4.7 x 10^42 ergs s^-1. We determine a rest-frame time lag between...... flux variations in the continuum and the Hbeta line of 6.3 (+2.6/-2.3) days. Combining our measurements with those of previous campaigns, we determine a weighted black hole mass of M_BH = 6.54 (+0.26/-0.25) x 10^7 M_sun based on all broad emission lines with suitable variability data. We confirm the...... reverberation-mapped AGNs as a whole....

  13. Levitating atmospheres of Eddington-luminosity neutron stars

    CERN Document Server

    Wielgus, Maciek; Kluzniak, Wlodek; Abramowicz, Marek; Narayan, Ramesh

    2015-01-01

    We construct models of static, spherically symmetric shells supported by the radiation flux of a luminous neutron star in the Schwarzschild metric. The atmospheres are disconnected from the star and levitate above its surface. Gas pressure and density inversion appear in the inner region of these atmospheres, which is a purely relativistic phenomenon. We account for the scattering opacity dependence on temperature and utilize the relativistic M1 closure scheme for the radiation tensor, hence allowing for a fully GR-consistent treatment of the photon flux and radiation tensor anisotropy. In this way we are able to address atmospheres of both large and moderate/low optical depths with the same set of equations. We discuss properties of the levitating atmospheres and find that they may indeed be optically thick, with the distance between star surface and the photosphere expanding as luminosity increases. These results may be relevant for the photosphereric radius expansion X-ray bursts.

  14. EGS4 calculations for a PEP-II luminosity monitor

    International Nuclear Information System (INIS)

    The Asymmetric B-Factory currently being built at SLAC consists of a 9 GeV electron storage ring and a 3 GeV positron storage ring, known as PEP-II, and a large detector called BABAR. Because the commissioning of PEP-II starts approximately one year ahead of the installation of BABAR, it is desirable to have a dedicated system in place beforehand for measuring and optimizing the luminosity of the colliding beams. Accordingly, the EGS4 Code System has been used in the design of a quartz-glass Cherenkov hodoscope that monitors high-energy showers, initiated by photons emanating from radiative-Bhabba interactions at the Interaction Point located 8.5 meters upbeam. In this paper the authors present the results of a series of EGS4 calculations to determine the spatial resolution of such a detector, as well as to determine if there will be any serious limitations caused by radiation damage

  15. Toward better simulations of planetary nebulae luminosity functions

    CERN Document Server

    Méndez, R H; Schönberner, D; Jacob, R; Steffen, M

    2008-01-01

    We describe a procedure for the numerical simulation of the planetary nebulae luminosity function (PNLF), improving on previous work (Mendez & Soffner 1997). Earlier PNLF simulations were based on an imitation of the observed distribution of the intensities of [O III] 5007 relative to Hbeta, generated predominantly using random numbers. We are now able to replace this by a distribution derived from the predictions of hydrodynamical PN models (Schoenberner et al. 2007), which are made to evolve as the central star moves across the HR diagram, using proper initial and boundary conditions. In this way we move one step closer to a physically consistent procedure for the generation of a PNLF. As an example of these new simulations, we have been able to reproduce the observed PNLF in the Small Magellanic Cloud.

  16. Fast Frontend Electronics for high luminosity particle detectors

    CERN Document Server

    Cardinali, M; Bondy, M I Ferretti; Hoek, M; Lauth, W; Rosner, C; Sfienti, C; Thiel, M

    2015-01-01

    Future experiments of nuclear and particle physics are moving towards the high luminosity regime, in order to access suppressed processes like rare B decays or exotic charmonium resonances. In this scenario, high rate capability is a key requirement for electronics instrumentation, together with excellent timing resolution for precise event reconstruction. The development of dedicated FrontEnd Electronics (FEE) for detectors has become increasingly challenging. A current trend in R&D is towards multipurpose FEE which can be easily adapted to a great variety of detectors, without impairing the required high performance. We report on high-precision timing solutions which utilise high-bandwidth preamplifiers and fast discriminators providing Time-over-Threshold information, which can be used for charge measurements or walk corrections thus improving the obtainable timing resolution. The output signal are LVDS and can be directly fed into a multi-hit TDC readout. The performance of the electronics was investi...

  17. New ATLAS pixel Front-End chip for upgraded luminosity

    Energy Technology Data Exchange (ETDEWEB)

    Hemperek, Tomasz; Arutinov, David; Barbero, Marlon; Karagounis, Michael; Wermes, Norbert [Physikalisches Institut, Universitaet Bonn (Germany)

    2009-07-01

    Motivated by the upcoming upgrades of the ATLAS hybrid pixel detector at CERN (Insertable B-Layer project 2012 and super-LHC upgrade 2017), a new Front-End IC (FE-I4) is being developed in a 130 nm technology to face the tightened requirements of the upgraded pixel system. The design goals are to reduce the pixel size, reduce material, improve powering scheme, and cope with the much higher hit rate coming from both the increased luminosity and the potential smaller radius of the innermost pixel layer. New technology features are being used like higher integration density for digital circuits, better radiation tolerance and triple-well transistors. The digital readout has been completely redesigned to achieve low inefficiencies with increased hit rates and provide higher output data bandwidth. A description of the FE-I4 design is given, focusing on the digital and data processing blocks.

  18. Intermediate luminosity optical transients during the grazing envelope evolution (GEE)

    CERN Document Server

    Soker, Noam

    2016-01-01

    By comparing photon diffusion time with gas outflow time, I argue that a large fraction of the energy carried by the jets during the grazing envelope evolution (GEE) might end in radiation, hence leading to an intermediate luminosity optical transient (ILOT). In the GEE a companion orbiting near the outskirts of the larger primary star accretes mass through an accretion disk, and launches jets that efficiently remove the envelope gas in the vicinity of the secondary star. In cases of high mass accretion rates onto the stellar companion the energy carried by the jets surpass the recombination energy from the ejected mass, and when the primary star is a giant this energy surpasses also the gravitational energy of the binary system. Some future ILOTs of giant stars might be better explained by the GEE than by merger and common envelope evolution without jets.

  19. Preliminary accelerator plans for maximizing the integrated LHC luminosity

    CERN Document Server

    Benedikt, Michael; Ruggiero, F; Ostojic, R; Scandale, Walter; Shaposhnikova, Elena; Wenninger, J

    2006-01-01

    A working group on "Proton Accelerators for the Future" (PAF) has been created in May 2005 by the CERN direction to elaborate a baseline scenario of the possible development and upgrade of the present Proton Accelerator Complex. This report is the result of the investigation conducted until the end of 2005, in close connection with the working group on "Physics Opportunities with Future Proton Accelerators" (POFPA) and is consistent with their recommendations. Focused on the goal of maximizing the integrated luminosity for the LHC experiments, a scenario of evolution is proposed, subject to further refinement using the future experience of commissioning and running-in the collider and its injector complex. The actions to be taken in terms of consolidation, R & D and improvement are outlined. The benefits for other types of physics are mentioned and will be investigated in more detail in the future.

  20. Models of hydrostatic magnetar atmospheres at high luminosities

    CERN Document Server

    van Putten, T; D'Angelo, C R; Baring, M G; Kouveliotou, C

    2012-01-01

    We investigate the possibility of Photospheric Radius Expansion (PRE) during magnetar bursts. Identification of PRE would enable a determination of the magnetic Eddington limit (which depends on field strength and neutron star mass and radius), and shed light on the burst mechanism. To do this we model hydrostatic atmospheres in a strong radial magnetic field, determining both their maximum extent and photospheric temperatures. We find that spatially-extended atmospheres cannot exist in such a field configuration: typical maximum extent for magnetar-strength fields is ~ 10m (as compared to 200 km in the non-magnetic case). Achieving balance of gravitational and radiative forces over a large range of radii, which is critical to the existence of extended atmospheres, is rendered impossible in strong fields due to the dependence of opacities on temperature and field strength. We conclude that high luminosity bursts in magnetars do not lead to expansion and cooling of the photosphere, as in the non-magnetic case....

  1. New ATLAS pixel Front-End chip for upgraded luminosity

    International Nuclear Information System (INIS)

    Motivated by the upcoming upgrades of the ATLAS hybrid pixel detector at CERN (Insertable B-Layer project 2012 and super-LHC upgrade 2017), a new Front-End IC (FE-I4) is being developed in a 130 nm technology to face the tightened requirements of the upgraded pixel system. The design goals are to reduce the pixel size, reduce material, improve powering scheme, and cope with the much higher hit rate coming from both the increased luminosity and the potential smaller radius of the innermost pixel layer. New technology features are being used like higher integration density for digital circuits, better radiation tolerance and triple-well transistors. The digital readout has been completely redesigned to achieve low inefficiencies with increased hit rates and provide higher output data bandwidth. A description of the FE-I4 design is given, focusing on the digital and data processing blocks

  2. The Physics Landscape of the High Luminosity LHC

    CERN Document Server

    Mangano, M

    2015-01-01

    We review the status of HEP after the first run of the LHC and discuss the opportunities offered by the HL-LHC, in light of the needs for future progress that are emerging from the data. The HL-LHC will push to the systematic limit the precision of most measurements of the Higgs boson, and will be necessary to firmly establish some of the more rare decays foreseen by the Standard Model, such as the decays to dimuons and to a Z+ photon pair. The HL-LHC luminosity will provide additional statistics required by the quantitative study of any discovery the LHC may achieve during the first 300 inverse femtobarn, and will further extend the discovery potential of the LHC, particularly for rare, elusive or low-sensitivity processes.

  3. The evolution of solar ultraviolet luminosity. [influence on planetary atmospheres

    Science.gov (United States)

    Zahnle, K. J.; Walker, J. C. G.

    1982-01-01

    Astronomical observations of stars analogous to the sun are used to construct a tentative account of the evolution of solar UV luminosity. Evidence exists that the young sun was a much more powerful source of energetic particles and radiation than it is today, and while on the main sequence, solar activity has declined as an inverse power law of age as a consequence of angular momentum loss to the solar wind. Observations of pre-main sequence stars indicate that before the sun reached the main sequence, it may have emitted as much as ten thousand times the amount of ultraviolet radiation that it does today. The impact of the results on knowledge of photochemistry and escape of constituents of primordial planetary atmospheres is discussed.

  4. The infrared luminosity function for low-mass stars

    International Nuclear Information System (INIS)

    The first infrared observational luminosity functions (LFs) for M dwarfs towards the South Galactic Pole (SGP) and the Hyades cluster are presented. We also give a definitive compilation of new and published VRIJHK data for 200 parallax stars, for deriving photometric parallaxes in such studies. Two-colour near-infrared/infrared diagrams of these data are used to demonstrate metallicity and gravity effects, and show that I-J is the purest temperature colour index. An MJ:I-J relation is given using high-quality trigonometric parallaxes from the new Yale catalogue. We describe the corrections to the LFs that are necessary to allow for magnitude errors (Malmquist effects), which have been incorrectly applied in recent determinations. (author)

  5. Preliminary study of a high luminosity e+ e- storage ring at a C.M. energy of 5 GeV

    International Nuclear Information System (INIS)

    The design of a facility for the study of tau-charm interactions, with 5 GeV C.M. energy and a luminosity of 1033/sqcm.s is investigated. The performances of some known storage rings are underlined. The influence of the emittances, space charge and collision rate limit, and the design constraints of the micro beta quadrupoles are discussed. Design examples and considerations of the sloping parts are included. The analysis shows that the round beam scheme saves a factor 2 on the stored current for a given luminosity, is very demanding in terms of tolerances for superconducting quadrupoles and requires one crossing point

  6. Luminosity function of faint Galactic sources in the Chandra bulge field

    CERN Document Server

    Revnivtsev, M; Forman, W; Churazov, E; Sunyaev, R

    2011-01-01

    We study the statistical properties of faint X-ray sources detected in the Chandra Bulge Field. The unprecedented sensitivity of the Chandra observations allows us to probe the population of faint Galactic X-ray sources down to luminosities L(2-10 keV)~1e30 erg/sec at the Galactic Center distance. We show that the luminosity function of these CBF sources agrees well with the luminosity function of sources in the Solar vicinity (Sazonov et al. 2006). The cumulative luminosity density of sources detected in the CBF in the luminosity range 1e30-1e32 erg/sec per unit stellar mass is L(2-10 keV)/M*=(1.7+/-0.3)e27 erg/sec/Msun. Taking into account sources in the luminosity range 1e32-1e34 erg/sec from Sazonov et al. (2006), the cumulative luminosity density in the broad luminosity range 1e30-1e34 erg/sec becomes L(2-10 keV)/M*=(2.4+/-0.4)e27 erg/sec/Msun. The majority of sources with the faintest luminosities should be active binary stars with hot coronae based on the available luminosity function of X-ray sources ...

  7. Silicon sensors for trackers at high-luminosity environment

    International Nuclear Information System (INIS)

    The planned upgrade of the LHC accelerator at CERN, namely the high luminosity (HL) phase of the LHC (HL-LHC foreseen for 2023), will result in a more intense radiation environment than the present tracking system that was designed for. The required upgrade of the all-silicon central trackers at the ALICE, ATLAS, CMS and LHCb experiments will include higher granularity and radiation hard sensors. The radiation hardness of the new sensors must be roughly an order of magnitude higher than in the current LHC detectors. To address this, a massive R&D program is underway within the CERN RD50 Collaboration “Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders” to develop silicon sensors with sufficient radiation tolerance. Research topics include the improvement of the intrinsic radiation tolerance of the sensor material and novel detector designs with benefits like reduced trapping probability (thinned and 3D sensors), maximized sensitive area (active edge sensors) and enhanced charge carrier generation (sensors with intrinsic gain). A review of the recent results from both measurements and TCAD simulations of several detector technologies and silicon materials at radiation levels expected for HL-LHC will be presented. - Highlights: • An overview of the recent results from the RD50 collaboration. • Accuracy of TCAD simulations increased by including both bulk and surface damage. • Sensors with n-electrode readout and MCz material offer higher radiation hardness. • 3D detectors are a promising choice for the extremely high fluence environments. • Detectors with an enhanced charge carrier generation under systematic investigation

  8. The Galaxy UV Luminosity Function before the Epoch of Reionization

    Science.gov (United States)

    Mason, Charlotte A.; Trenti, Michele; Treu, Tommaso

    2015-11-01

    We present a model for the evolution of the galaxy ultraviolet (UV) luminosity function (LF) across cosmic time where star formation is linked to the assembly of dark matter halos under the assumption of a mass-dependent, but redshift-independent, efficiency. We introduce a new self-consistent treatment of the halo star formation history, which allows us to make predictions at z > 10 (lookback time ?500 Myr), when growth is rapid. With a calibration at a single redshift to set the stellar-to-halo mass ratio, and no further degrees of freedom, our model captures the evolution of the UV LF over all available observations (0 ? z ? 10). The significant drop in luminosity density of currently detectable galaxies beyond z 8 is explained by a shift of star formation toward less massive, fainter galaxies. Assuming that star formation proceeds down to atomic cooling halos, we derive a reionization optical depth ? ={0.056}-0.010+0.007, fully consistent with the latest Planck measurement, implying that the universe is fully reionized at z={7.84}-0.98+0.65. In addition, our model naturally produces smoothly rising star formation histories for galaxies with L ? L* in agreement with observations and hydrodynamical simulations. Before the epoch of reionization at z > 10 we predict the LF to remain well-described by a Schechter function, but with an increasingly steep faint-end slope (? -3.5 at z 16). Finally, we construct forecasts for surveys with James Webb Space Telescope (JWST) and Wide-field Infrared Survey Telescope (WFIRST) and predict that galaxies out to z 14 will be observed. Galaxies at z > 15 will likely be accessible to JWST and WFIRST only through the assistance of strong lensing magnification.

  9. Silicon sensors for trackers at high-luminosity environment

    Energy Technology Data Exchange (ETDEWEB)

    Peltola, Timo, E-mail: timo.peltola@helsinki.fi

    2015-10-01

    The planned upgrade of the LHC accelerator at CERN, namely the high luminosity (HL) phase of the LHC (HL-LHC foreseen for 2023), will result in a more intense radiation environment than the present tracking system that was designed for. The required upgrade of the all-silicon central trackers at the ALICE, ATLAS, CMS and LHCb experiments will include higher granularity and radiation hard sensors. The radiation hardness of the new sensors must be roughly an order of magnitude higher than in the current LHC detectors. To address this, a massive R&D program is underway within the CERN RD50 Collaboration “Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders” to develop silicon sensors with sufficient radiation tolerance. Research topics include the improvement of the intrinsic radiation tolerance of the sensor material and novel detector designs with benefits like reduced trapping probability (thinned and 3D sensors), maximized sensitive area (active edge sensors) and enhanced charge carrier generation (sensors with intrinsic gain). A review of the recent results from both measurements and TCAD simulations of several detector technologies and silicon materials at radiation levels expected for HL-LHC will be presented. - Highlights: • An overview of the recent results from the RD50 collaboration. • Accuracy of TCAD simulations increased by including both bulk and surface damage. • Sensors with n-electrode readout and MCz material offer higher radiation hardness. • 3D detectors are a promising choice for the extremely high fluence environments. • Detectors with an enhanced charge carrier generation under systematic investigation.

  10. Jet or Shock Breakout? The Low-Luminosity GRB 060218

    Science.gov (United States)

    Irwin, Christopher; Chevalier, Roger

    2016-01-01

    We consider a model for the long-duration, low-luminosity gamma-ray burst GRB 060218 that plausibly accounts for multiwavelength observations to day 20. The components of our model are: (1) a long-lived (tj ~ 3000 s) central engine and accompanying low-luminosity (Lj ~ 1045 erg s-1), mildly relativistic jet; (2) a low-mass (~ 10-2 Msun) envelope surrounding the progenitor star; and (3) a modest amount of dust (AV ~ 0.1) in the circumstellar or interstellar environment. Blackbody emission from the transparency radius in a low-power jet outflow can fit the prompt thermal X-ray emission, and the prompt nonthermal X-rays and ?-rays may be produced via Compton scattering of thermal photons from hot leptons in the jet interior or the external shocks. The later mildly relativistic phase of this outflow can produce the radio emission via synchrotron radiation from the forward shock. Meanwhile, interaction of the associated SN 2006aj with a circumstellar envelope extending to ~ 1013 cm can explain the early optical peak. The X-ray afterglow can be interpreted as a light echo of the prompt emission from dust at ~ 30 pc. Our model is a plausible alternative to that of Nakar, who recently proposed shock breakout of a jet smothered by an extended envelope as the source of prompt emission. Both our results and Nakar's suggest that ultra-long bursts such as GRB 060218 and GRB 100316D may originate from unusual progenitors with extended circumstellar envelopes, and that a jet is necessary to decouple the prompt high-energy emission from the supernova.

  11. Jet or Shock Breakout? The Low-Luminosity GRB 060218

    Science.gov (United States)

    Irwin, Christopher M.; Chevalier, Roger A.

    2016-05-01

    We consider a model for the low-luminosity gamma-ray burst GRB 060218 that plausibly accounts for multiwavelength observations to day 20. The model components are: (1) a long-lived (tj ˜ 3000 s) central engine and accompanying low-luminosity (Lj ˜ 1047 erg s-1), mildly relativistic (γ ˜ 10) jet; (2) a low-mass (˜4 × 10-3M⊙) envelope surrounding the progenitor star; and (3) a modest amount of dust (AV ˜ 0.1 mag) in the circumstellar or interstellar environment. Blackbody emission from the transparency radius in a low-power jet outflow can fit the prompt thermal X-ray emission, and the nonthermal X-rays and γ-rays may be produced via Compton scattering of thermal photons from hot leptons in the jet interior or the external shocks. The later mildly relativistic phase of this outflow can produce the radio emission via synchrotron radiation from the forward shock. Meanwhile, interaction of the associated SN 2006aj with a circumstellar envelope extending to ˜1013 cm can explain the early optical emission. The X-ray afterglow can be interpreted as a light echo of the prompt emission from dust at ˜30 pc. Our model is a plausible alternative to that of Nakar, who recently proposed shock breakout of a jet smothered by an extended envelope as the source of prompt emission. Both our results and Nakar's suggest that bursts such as GRB 060218 may originate from unusual progenitors with extended circumstellar envelopes, and that a jet is necessary to decouple the prompt emission from the supernova.

  12. A Spitzer Comparison of Protostellar Luminosity Functions Across Diverse Star Forming Enviornments

    Science.gov (United States)

    Kryukova, Erin; Megeath, S.

    2011-01-01

    We approach the fundamental question "How does environment affect star formation and the properties of nascent stars? by comparing populations of protostars in diverse environments. In our study, we present a sample of over 900 Spitzer-identified protostars from the nearby (within 1 kpc) star forming clouds Orion A & B, Cep OB3, Serpens, Perseus, Ophiuchus, Taurus, Lupus, Chamaeleon, and Mon R2, and the more distant massive star forming region Cyg X (at 1700 pc); these encompass a range of cloud environments including regions of clustered and isolated star formation and regions of low and high mass star formation. Using Spitzer 3 to 24 micron photometry combined with 2MASS J, H, and K photometry we calculate SED slope and mid-IR luminosities for each of our protostars. We then use a sample of c2d protostars with known bolometric luminosities to create an empirical mid-IR/bolometric luminosity relationship, and determine bolometric luminosities for our protostars. Luminosity functions are then created for each cloud and corrected for contamination due to background galaxies, edge-on Class II YSOs, and reddened Class II YSOs. In each cloud, the luminosity function peaks near 1 Lsun, and in the more massive clouds that form higher mass stars, the luminosity functions show a tail extending up towards 1000 Lsun. We compare the luminosity functions in the different clouds and identify significant differences between the functions in different clouds, demonstrating that the luminosity function depends on the host cloud. We examine luminosity functions as a function of the surrounding density of young stars, and find that in Orion and Cyg X, and to some extent Ophiuchus, the luminosity functions of protostars in dense environments are statistically different than those in more isolated environments, with the luminosity function in dense environments in Orion and Cyg X extending to higher luminosities.

  13. Virial and Jet-induced Velocities in Seyfert Galaxies. III. Galaxy Luminosity as Virial Parameter

    Science.gov (United States)

    Whittle, Mark

    1992-03-01

    This is the third paper in a series which aims to identify the acceleration mechanisms acting on the ionized gas in the narrow line region (NLR) of Seyfert galaxies. Using the sample and approach described in Papers I and II, galaxy luminosity, M_tot_, and bulge luminosity, M_bul_, are taken as the principal parameters describing nuclear virial speeds, while radio luminosity and morphology are used to track possible nuclear perturbations. The fundamental conclusions from Paper II are confirmed. Plots of [O III] FWHM versus M_tot_ or M_bul_ show strong correlations (R ~ 0.6, P_null_~10^-8^) indicating that gravity plays a key role in defining the NLR velocity field. However, Seyfert galaxies with linear radio morphology and high radio luminosity (L_1415_>=10^22.5^ W Hz^-1^) have systematically broader lines, suggesting that acceleration of NLR gas by outflowing jets is also important in some Seyferts. For Seyfert galaxies without linear radio sources, [O III] FWHM is more fundamentally related to M_bul_ than M_tot_. Indeed, the scatter in the M_tot_ versus [O III] FWHM relation has a Hubble-type dependence which is identical to the Hubble-type dependence of the bulge/total ratio used in the evaluation of M_bul_ from M_tot_. This agreement between photometrically defined bulge/total ratio for normal spirals and kinematically defined bulge/total ratio for Seyfert galaxies lends powerful support to the argument that M_bul_ is playing the fundamental role. A fit to the M_bul_ versus [O III] FWHM relation of the form L_bul_ is proportional to (FWHM)^n^ gives gradient n ~ 2.2, zero point FWHM_20_~ 250 km s^-1^ (where FWHM_20_ = FWHM at M_bul_ = -20), and ~1 mag scatter. This is compared to the Faber-Jackson relation for normal galaxies, L_bul_ is proportional to (FWHM_stars_)^n^, where n ~ 3.2 and FWHM_20_~360 km s^-1^. The overall similarity of these two relations supports the virial origin of [O III] FWHM. In detail, however, the Seyferts appear offset from the Faber-Jackson relation. The offset may be viewed in two ways. Either FWHM_[O III]~ 0.7 x FWHM_stars_, or Seyfert galaxies are ~1 mag more luminous than normal spirals for a given bulge (or total) mass. The possibility that Seyfert galaxies are overluminous is investigated using the Tully-Fisher relation, M_tot_ versus {DELTA}V^c^_rot_. There is some indication that Seyfert galaxies, particularly those of early type, are offset, although the effect is confused by the underlying Hubble-type dependence of the Tully-Fisher relation. The situation is clarified using a normalized Tully-Fisher plot in which this type dependence is removed. It seems that Seyfert galaxies are indeed offset relative to normal spirals (P_null_ ~ 10^-5^), implying M/L ratios lower by a factor ~1.5-2.0. Both the Faber-Jackson and Tully-Fisher offsets for Seyfert galaxies are compared to similar offsets found previously for peculiar radio galaxies and spirals in compact groups. It is possible that enhanced star formation causes lower M/L ratios in Seyfert galaxies, although the absence of a correlation between offset and galaxy color excess fails to support this possibility. Offsets on the M_bul_ versus [O III] FWHM plot are further analyzed by introducing additional variables. There is no dependence on Seyfert type, inclination, Hubble type, or redshift. Unbarred Seyfert galaxies show a tighter correlation than barred Seyfert galaxies (P_null_ ~ 0.04) suggesting that bars can modify the NLR velocity field. The strongest result, however, is that disturbed and interacting Seyfert galaxies have significantly broader lines (P_null_ ~ 10^-4^), showing that external perturbations can influence nuclear gas. A plot of Faber-Jackson offsets against perturbation class (a 1-6 ranking scale based on Dahari's IAC parameter) shows a positive correlation which converges on zero offset for maximally disturbed galaxies. If offsets reflect dissipational settling of gas into a soft nuclear potential, then external perturbations may act to reestablish overall virial equilibrium. The historically significant correlations between [O III] FWHM and radio luminosity, L_1415_, and [O III] luminosity, L_5007_, are reanalyzed in the light of jet perturbations and the virial relations. Although the [O III] FWHM versus L_1415_ correlation is very strong (R ~ 0.6, P_null_~ 10^-10^), removing the luminous linear radio sources merely weakens the correlation but does not destroy it. The remaining correlation is indirect and exists principally because L_1415_ is itself tied to the virial parameter M_bul_ in a relation of the form L_radio_ is proportional to L^2.6^_bul_ (R~ 0.6, P_null_~10^- 7^). Interestingly, similar correlations with M_tot_ or M_disk_ are significantly weaker, suggesting that development of the nuclear radio source depends on the bulge potential, although the origin of this dependence is not yet clear. The relation between [O III] FWHM and [O III] luminosity (R~0.4, P_null_~10^-6^) is probably of indirect origin, since L_5007_ correlates very strongly with L_1415_(L_5007_ is proportional to L^1.1^_1415_,R~0.7,P_null_~10^-16^) and also with M_bul_(L_5007_ is proportional to L^2.5^_bul_, R~0.5,P_null_~10^-7^ both of which share direct causal ties to [O III] FWHM. Interestingly, the correlation between L_5007_ and M_bul_ is stronger than with either M_tot_ or M_disk_. This reinforces the suggestion that the spheroidal mass plays an important role in defining not only NLR kinematics but also NLR luminosities, both radio and emission line.

  14. Measurement of the luminosity in the ZEUS experiment at HERA II

    Energy Technology Data Exchange (ETDEWEB)

    Adamczyk, L.; Bold, T. [AGH Univ. of Science and Technology, Cracow (Poland); Andruszkow, J. [Polish Academy of Sciences, Cracow (Poland). Inst. of Nuclear Physics] [and others

    2013-06-15

    The luminosity in the ZEUS detector was measured using photons from electron bremsstrahlung. In 2001 the HERA collider was upgraded for operation at higher luminosity. At the same time the luminosity-measuring system of the ZEUS experiment was modified to tackle the expected higher photon rate and synchrotron radiation. The existing lead-scintillator calorimeter was equipped with radiation hard scintillator tiles and shielded against synchrotron radiation. In addition, a magnetic spectrometer was installed to measure the luminosity independently using photons converted in the beam-pipe exit window. The redundancy provided a reliable and robust luminosity determination with a systematic uncertainty of 1.7%. The experimental setup, the techniques used for luminosity determination and the estimate of the systematic uncertainty are reported.

  15. Perfomance of novel and upgraded instrumentation for luminosity and beam conditions measurements in CMS

    CERN Document Server

    Leonard, Jessica Lynn

    2015-01-01

    The beam monitoring and luminosity systems of the CMS experiment are enhanced by several new and upgraded sub-detectors to match the challenges of the LHC operation and physics program at increased energy and higher luminosity. A dedicated pixelated luminosity telescope is installed for a fast and precise luminosity measurement. This detector measures coincidences between several three-layer telescopes of silicon pixel detectors to arrive at luminosity for each colliding LHC bunch pair. An upgraded fast beam conditions monitor measures the particle flux using single crystalline diamond sensors. It is equipped with a dedicated front-end ASIC produced in 130 nm CMOS technology. The excellent time resolution is used to separate collision products from machine induced background, thus serving as online luminosity measurement. A new beam-halo monitor at larger radius exploits Cerenkov light from fused silica to provide direction sensitivity and excellent time resolution to separate incoming and outgoing particles....

  16. The GALEX Ultraviolet Luminosity Function of the Cluster of Galaxies A1367

    Science.gov (United States)

    Cortese, L.; Boselli, A.; Gavazzi, G.; Iglesias-Paramo, J.; Madore, B. F.; Barlow, T.; Bianchi, L.; Byun, Y.-I.; Donas, J.; Forster, K.; Friedman, P. G.; Heckman, T. M.; Jelinsky, P.; Lee, Y.-W.; Malina, R.; Martin, D. C.; Milliard, B.; Morrissey, P.; Neff, S.; Rich, R. M.; Schiminovich, D.; Siegmund, O.; Small, T.; Szalay, A. S.; Treyer, M. A.; Welsh, B.; Wyder, T. K.

    2005-04-01

    We present the Galaxy Evolution Exlorer (GALEX) near-ultraviolet (2310 ) and far-ultraviolet (1530 ) galaxy luminosity functions of the nearby cluster of galaxies A1367 in the magnitude range -20.3FOCA and FAUST experiments, but they display a steeper faint-end slope than the GALEX luminosity function for local field galaxies. Using spectrophotometric optical data, we select star-forming systems from quiescent galaxies and study their separate contributions to the cluster luminosity function. We find that the UV luminosity function of cluster star-forming galaxies is consistent with the field. The difference between the cluster and field luminosity functions is entirely due to the contribution at low luminosities (MAB>-16 mag) of non-star-forming, early-type galaxies that are significantly overdense in clusters.

  17. Measurement of the luminosity in the ZEUS experiment at HERA II

    International Nuclear Information System (INIS)

    The luminosity in the ZEUS detector was measured using photons from electron bremsstrahlung off protons. In 2001 the HERA collider was upgraded for operation at higher luminosity. At the same time the luminosity-measuring system of the ZEUS experiment was modified to tackle the expected higher photon rate and synchrotron radiation. The existing lead-scintillator calorimeter was equipped with radiation hard scintillator tiles and shielded against synchrotron radiation. In addition, a magnetic spectrometer was installed to measure the luminosity independently using photons converted in the beam-pipe exit window. The redundancy provided a reliable and robust luminosity determination with a systematic uncertainty of 1.7%. The experimental setup, the techniques used for luminosity determination and the estimate of the systematic uncertainty are reported

  18. On the core-mass-shell-luminosity relation for shell-burning stars

    International Nuclear Information System (INIS)

    Core-mass-shell-luminosity relations for several types of shell-burning star have been calculated using simultaneous differential equations derived from simple homology approximations. The principal objective of obtaining a mass-luminosity relation for helium giants was achieved. This relation gives substantially higher luminosities than the equivalent relation for H-shell stars with core masses greater than 1 solar mass. The algorithm for calculating mass-luminosity relations in this fashion was investigated in detail. Most of the assumptions regarding the physics in the shell do not play a critical role in determining the core-mass-shell-luminosity relation. The behaviour of the core-mass-core-radius relation for a growing degenerate core as a single unique function of mass and growth rate needs to be defined before a single core-mass-shell-luminosity relation for all H-shell stars can be obtained directly from the homology approximations. (author)

  19. Infrared observations of NGC 3603. I. New constraints on cluster radius and Ks-band luminosity function

    Science.gov (United States)

    Nürnberger, D. E. A.; Petr-Gotzens, M. G.

    2002-02-01

    We have performed deep K_s-band observations of the starburst region NGC 3603 with the infrared camera ISAAC mounted on the VLT Antu. The total area covered by our data stretches from the NGC 3603 starburst cluster towards the south up to a maximal distance of about 370'' ( ~ 12 pc). This enables us to reconsider and redetermine the radial extent of the cluster which is found to be about 150'' +/- 15'' ( ~ 5 pc), exceeding previous estimates by a factor of 2.5. King model fits are used to disentangle the count statistics of cluster stars from those of field stars. With knowledge of the cluster radius we then construct and analyze the Ks-band luminosity function (KLF) of the NGC 3603 starburst cluster. The KLF for cluster radii >30'' is rising down to the completeness limit of our study at Ks ~ 17m- 17.5m, corresponding to 1 Myr old cluster members of M ~ 0.5 Msolar. For the range of intermediate luminosity stars we obtain a KLF slope of alpha = 0.35 +/- 0.02 which is consistent with a Miller-Scalo type initial mass function (IMF) of a ~ 1 Myr old stellar cluster if one assumes a power-law index of beta ~ 2 for the mass-luminosity relation of both intermediate mass main sequence stars and low mass pre-main sequence stars. At the high luminosity end the observed KLF likely flattens (alpha ~ 0.2), being consistent with a Salpeter type IMF for NGC 3603's massive main sequence stars. Based on observations obtained at the European Southern Observatory, Paranal, Chile under proposal number 63.I-0608A.

  20. The luminosity function for the CfA redshift survey slices

    Science.gov (United States)

    De Lapparent, Valerie; Geller, Margaret J.; Huchra, John P.

    1989-01-01

    The luminosity function for two complete slices of the extension of the CfA redshift survey is calculated. The nonparametric technique of Lynden-Bell (1971) and Turner (1979) is used to determine the shape for the luminosity function of the 12 deg slice of the redshift survey. The amplitude of the luminosity function is determined, taking large-scale inhomogeneities into account. The effects of the Malmquist bias on a magnitude-limited redshift survey are examined, showing that the random errors in the magnitudes for the 12 deg slice affect both the determination of the luminosity function and the spatial density constrast of large scale structures.

  1. A composite HII region luminosity function in H alpha of unprecedented statistical weight

    CERN Document Server

    Bradley, T R; Beckman, J E; Folkes, S L

    2006-01-01

    Context. Statistical properties of HII region populations in disk galaxies yield important clues to the physics of massive star formation. Aims. We present a set of HII region catalogues and luminosity functions for a sample of 56 spiral galaxies in order to derive the most general form of their luminosity function. Methods. HII region luminosity functions are derived for individual galaxies which, after photometric calibration, are summed to form a total luminosity function comprising 17,797 HII regions from 53 galaxies. Results. The total luminosity function, above its lower limit of completeness, is clearly best fitted by a double power law with a significantly steeper slope for the high luminosity portion of the function. This change of slope has been reported in the literature for individual galaxies, and occurs at a luminosity of log L = 38.6\\pm0.1 (L in erg/s) which has been termed the Stromgren luminosity. A steep fall off in the luminosity function above log L = 40 is also noted, and is related to an...

  2. Energy and Beam-Offset dependence of the Luminosity weighted depolarization for CLIC

    CERN Document Server

    Esberg, Jakob; Uggerhoj, Ulrik; Dalena, Barbara

    2011-01-01

    We report on simulations of e+e- depolarization due to beam-beam effects. These effects are studied for CLIC at 3 TeV, using GUINEA PIG++. We find a strong energy dependence of the luminosity weighted depolarization. In the luminosity peak at CLIC the total luminosity weighted depolarization remains below the one per-mil level. The effect of a vertical offset on the energy dependent depolarization is investigated. The depolarization in the luminosity peak remains below per-cent level even for 5sy offsets.

  3. The Herschel ATLAS: Evolution of the 250 Micrometer Luminosity Function Out to z = 0.5

    Science.gov (United States)

    Dye, S.; Dunne, L.; Eales, S.; Smith, D. J. B.; Amblard, A.; Auld, R.; Baes, M.; Baldry, I. K.; Bamford, S.; Blain, A. W.; Bonfield, D. G.; Bremer, M.; Burgarella, D.; Buttiglione, S.; Cameron, E.; Cava, A.; Clements, D. L.; Cooray, A.; Croom, S.; Dariush, A.; de Zotti, G.; Driver, S.; Dunlop, J. S.; Frayer, D.; Leeuw, L.

    2010-01-01

    We have determined the luminosity function of 250 micrometer-selected galaxies detected in the approximately equal to 14 deg(sup 2) science demonstration region of the Herschel-ATLAS project out to a redshift of z = 0.5. Our findings very clearly show that the luminosity function evolves steadily out to this redshift. By selecting a sub-group of sources within a fixed luminosity interval where incompleteness effects are minimal, we have measured a smooth increase in the comoving 250 micrometer luminosity density out to z = 0.2 where it is 3.6(sup +1.4) (sub -0.9) times higher than the local value.

  4. Estimating active region luminosity using EVE/SDO observations

    Science.gov (United States)

    Kazachenko, Maria D.; Hudson, H. S.; Fisher, G. H.; Canfield, R. C.

    2013-07-01

    Do solar active regions typically radiate more coronal energy during flares than the quiescent periods between them? This is a fundamental question for storage and release models of flares and active regions, yet it is presently poorly answered by observations. The EUV Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO) provides spectrally resolved observations of the Sun in the "Sun-as-a-point source" mode. It covers a wide range of temperatures and thus allows a detailed study of thermal emissions. Here we present two approaches for computing the active region luminosity, using EVE observations of fourteen Fe lines (FeIX-FeXXIV). In the first approach, we analyze EVE data in a time-series sense, when only one active region is present on the disk; this allows us to subtract the background due to the quiet sun and get the contribution from the active region alone. In the second approach, we analyze correlations of the radiative signatures with proxy indices (total solar magnetic and Poynting fluxes) during several months of data, when multiple active regions are present on the solar disk. We discuss capabilities of the two approaches, and what we can learn from them.Abstract (2,250 Maximum Characters): Do solar active regions typically radiate more coronal energy during flares than the quiescent periods between them? This is a fundamental question for storage and release models of flares and active regions, yet it is presently poorly answered by observations. The EUV Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO) provides spectrally resolved observations of the Sun in the "Sun-as-a-point source" mode. It covers a wide range of temperatures and thus allows a detailed study of thermal emissions. Here we present two approaches for computing the active region luminosity, using EVE observations of fourteen Fe lines (FeIX-FeXXIV). In the first approach, we analyze EVE data in a time-series sense, when only one active region is present on the disk; this allows us to subtract the background due to the quiet sun and get the contribution from the active region alone. In the second approach, we analyze correlations of the radiative signatures with proxy indices (total solar magnetic and Poynting fluxes) during several months of data, when multiple active regions are present on the solar disk. We discuss capabilities of the two approaches, and what we can learn from them.

  5. Near-infrared luminosity function in the Coma cluster

    Science.gov (United States)

    Andreon, S.; Pell, R.

    2000-01-01

    We present the near-infrared H band luminosity function (hereafter LF) of the Coma cluster of galaxies. It is the deepest ever computed in the near-infrared, for any type of environment, extending over 7 magnitudes, down to ~ M_H*+6. The LF was computed on a near-infrared selected sample of galaxies whose photometry, complete down to the typical dwarf luminosity, is presented in a companion paper. The Coma LF can be described by a Schechter function with intermediate slope (alpha ~ -1.3), plus a dip at M_H ~ -22 mag. The shape of the Coma LF in H band is quite similar to the one found in the B band and, with less confidence, to the R band LF as well. The similarity of the LF in the optical and H bands implies that in the central region of Coma there is no new population of galaxies which is too faint to be observed in the optical band (because dust enshrouded, for instance), down to the magnitudes of dwarfs. The exponential cut of the LF at the bright end is in good agreement with the one derived from shallower near-infrared samples of galaxies, both in clusters and in the field. This fact is suggestive of a similarity of the tip of the mass function of galaxies, irrespective of the environment where they are found. The dip at M_H ~ -22 mag is instead unique among all the so far measured near-infrared LF, although several published observations are not deep enough or spanning a suitable wide field to distinctly detect this feature. The faint end of the LF, reaching M_H ~ -19 mag (roughly M_B ~ -15), is steep, but less than previously suggested from shallower near-infrared observations of an adjacent region in the Coma cluster. The differences between our measured LF and that measured previously in other regions suggest a dependency on environment of the faint end of the mass function (below M*+2.5). Based on observations collected with the Tlescope Bernard Lyot, at the Pic du Midi Observatory, operated by INSU (CNRS).

  6. L1Track: a Fast Level 1 Track Trigger for the ATLAS High Luminosity Upgrade

    CERN Document Server

    Cerri, Alessandro; The ATLAS collaboration

    2015-01-01

    With the planned high-luminosity upgrade of the LHC, the ATLAS detector will see its collision rate increased by approximately a factor of 5 with respect to the current LHC design. Due to this the pile-up collisions will increase by a similar factor. The earliest, hardware based, ATLAS trigger stage ("Level 1") will have to provide an higher rejection factor in a more difficult environment. The Level 1 trigger architecture needs therefore to be improved. A new Level 1 trigger architecture is under study, which, in addition of the “regions of interest” identified by the calorimetry and the muon chambers, also includes the possibility of extracting tracking information and use it for the decision taking process. The expected trigger rates at HL-LHC and the available latency are the key ingredients that will drive the new design. A low-latency and accurate tracking trigger system is being developed in the context of this additional trigger refinement. The design results in a substantial modification of the A...

  7. Field Tolerances for the Triplet Quadrupoles of the LHC High Luminosity Lattice

    Energy Technology Data Exchange (ETDEWEB)

    Nosochkov, Yuri; Cai, Y.; Jiao, Y.; Wang, M-H.; /SLAC; Fartoukh, S.; Giovannozzi, M.; Maria, R.de; McIntosh, E.

    2012-06-25

    It has been proposed to implement the so-called Achromatic Telescopic Squeezing (ATS) scheme in the LHC high luminosity (HL) lattice to reduce beta functions at the Interaction Points (IP) up to a factor of 8. As a result, the nominal 4.5 km peak beta functions reached in the Inner Triplets (IT) at collision will be increased by the same factor. This, therefore, justifies the installation of new, larger aperture, superconducting IT quadrupoles. The higher beta functions will enhance the effects of the triplet quadrupole field errors leading to smaller beam dynamic aperture (DA). To maintain the acceptable DA, the effects of the triplet field errors must be re-evaluated, thus specifying new tolerances. Such a study has been performed for the so-called '4444' collision option of the HL-LHC layout version SLHCV3.01, where the IP beta functions are reduced by a factor of 4 in both planes with respect to a pre-squeezed value of 60 cm at two collision points. The dynamic aperture calculations were performed using SixTrack. The impact on the triplet field quality is presented.

  8. Constraining the minimum luminosity of high redshift galaxies through gravitational lensing

    International Nuclear Information System (INIS)

    We simulate the effects of gravitational lensing on the source count of high redshift galaxies as projected to be observed by the Hubble Frontier Fields program and the James Webb Space Telescope (JWST) in the near future. Taking the mass density profile of the lensing object to be the singular isothermal sphere (SIS) or the Navarro-Frenk-White (NFW) profile, we model a lens residing at a redshift of zL = 0.5 and explore the radial dependence of the resulting magnification bias and its variability with the velocity dispersion of the lens, the photometric sensitivity of the instrument, the redshift of the background source population, and the intrinsic maximum absolute magnitude (Mmax) of the sources. We find that gravitational lensing enhances the number of galaxies with redshifts z?> 13 detected in the angular region ?E/2 ? ? ? 2?E (where ?E is the Einstein angle) by a factor of ? 3 and 1.5 in the HUDF (df/d?0 ? 9 nJy) and medium-deep JWST surveys (df/d?0 ? 6 nJy). Furthermore, we find that even in cases where a negative magnification bias reduces the observed number count of background sources, the lensing effect improves the sensitivity of the count to the intrinsic faint-magnitude cut-off of the Schechter luminosity function. In a field centered on a strong lensing cluster, observations of z?> 6 and z?> 13 galaxies with JWST can be used to infer this cut-off magnitude for values as faint as Mmax ? -14.4 and -16.1 mag (Lmin ? 2.5 1026 and 1.2 1027 erg s?1 Hz?1) respectively, within the range bracketed by existing theoretical models. Gravitational lensing may therefore offer an effective way of constraining the low-luminosity cut-off of high-redshift galaxies

  9. Correlated fluctuations in luminosity distance and the importance of peculiar motion in supernova surveys

    International Nuclear Information System (INIS)

    Large scale structure introduces two different kinds of errors in the luminosity distance estimates from standardizable candles such as supernovae Ia (SNe)--a Poissonian scatter for each SN and a coherent component due to correlated fluctuations between different SNe. Increasing the number of SNe helps reduce the first type of error but not the second. The coherent component has been largely ignored in forecasts of dark energy parameter estimation from upcoming SN surveys. For instance it is commonly thought, based on Poissonian considerations, that peculiar motion is unimportant, even for a low redshift SN survey such as the Nearby Supernova Factory (SNfactory; z=0.03-0.08), which provides a useful anchor for future high redshift surveys by determining the SN zero point. We show that ignoring coherent peculiar motion leads to an underestimate of the zero-point error by about a factor of 2, despite the fact that SNfactory covers almost half of the sky. More generally, there are four types of fluctuations: peculiar motion, gravitational lensing, gravitational redshift and what is akin to the integrated Sachs-Wolfe effect. Peculiar motion and lensing dominates at low and high redshifts, respectively. Taking into account all significant luminosity distance fluctuations due to large scale structure leads to a degradation of up to 60% in the determination of the dark energy equation of state from upcoming high redshift SN surveys, when used in conjunction with a low redshift anchor such as the SNfactory. The most relevant fluctuations are the coherent ones due to peculiar motion and the Poissonian ones due to lensing, with peculiar motion playing the dominant role. We also discuss to what extent the noise here can be viewed as a useful signal, and whether corrections can be made to reduce the degradation

  10. PHOTOMETRIC PROPERTIES AND LUMINOSITY FUNCTION OF NEARBY MASSIVE EARLY-TYPE GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    He, Y. Q. [University of Chinese Academy of Sciences, Beijing 100049 (China); Xia, X. Y.; Hao, C. N. [Tianjin Astrophysics Center, Tianjin Normal University, Tianjin 300387 (China); Jing, Y. P. [Center for Astronomy and Astrophysics, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Mao, S. [National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012 (China); Li, Cheng, E-mail: xyxia@bao.ac.cn [Partner Group of the Max Planck Institute for Astrophysics at the Shanghai Astronomical Observatory and Key Laboratory for Research in Galaxies and Cosmology of Chinese Academy of Sciences, Nandan Road 80, Shanghai 200030 (China)

    2013-08-10

    We perform photometric analyses of a bright early-type galaxy sample with 2949 galaxies (M{sub r} < -22.5 mag) in the redshift range of 0.05-0.15, drawn from the Sloan Digital Sky Survey (SDSS) DR7 with morphological classification from Galaxy Zoo 1. We measure the Petrosian and isophotal magnitudes, as well as the corresponding half-light radius for each galaxy. We find that for the brightest galaxies (M{sub r} < -23 mag), our Petrosian magnitudes and isophotal magnitudes to 25 mag arcsec{sup -2} and 1% of the sky brightness are on average 0.16 mag, 0.20 mag, and 0.26 mag brighter than the SDSS Petrosian values, respectively. In the first case, the underestimations are caused by overestimations in the sky background by the SDSS PHOTO algorithm, while the latter two are also due to deeper photometry. Similarly, the typical half-light radii (r{sub 50}) measured by the SDSS algorithm are smaller than our measurements. As a result, the bright end of the r-band luminosity function is found to decline more slowly than previous works. Our measured luminosity densities at the bright end are more than one order of magnitude higher than those of Blanton et al., and the stellar mass densities at M{sub *} {approx} 5 Multiplication-Sign 10{sup 11} M{sub Sun} and M{sub *} {approx} 10{sup 12} M{sub Sun} are a few tenths and a factor of a few higher than those of Bernardi et al. These results may significantly alleviate the tension in the assembly of massive galaxies between observations and predictions of the hierarchical structure formation model.

  11. Variability Selected Low-Luminosity Active Galactic Nuclei in the 4 Ms Chandra Deep Field-South

    Science.gov (United States)

    Young, M.; Brandt, W. N.; Xue, Y. Q.; Paolillo, D. M.; Alexander, F. E.; Bauer, F. E.; Lehmer, B. D.; Luo, B.; Shemmer, O.; Schneider, D. P.; Vignail, C.

    2012-01-01

    The 4 Ms Chandra Deep Field-South (CDF-S) and other deep X-ray surveys have been highly effective at selecting active galactic nuclei (AGN). However, cosmologically distant low-luminosity AGN (LLAGN) have remained a challenge to identify due to significant contribution from the host galaxy. We identify long-term X ray variability (approx. month years, observed frame) in 20 of 92 CDF-S galaxies spanning redshifts approx equals 00.8 - 1.02 that do not meet other AGN selection criteria. We show that the observed variability cannot be explained by X-ray binary populations or ultraluminous X-ray sources, so the variability is most likely caused by accretion onto a supermassive black hole. The variable galaxies are not heavily obscured in general, with a stacked effective power-law photon index of Gamma(sub Stack) approx equals 1.93 +/- 0.13, and arc therefore likely LLAGN. The LLAGN tend to lie it factor of approx equal 6-89 below the extrapolated linear variability-luminosity relation measured for luminous AGN. This may he explained by their lower accretion rates. Variability-independent black-hole mass and accretion-rate estimates for variable galaxies show that they sample a significantly different black hole mass-accretion-rate space, with masses a factor of 2.4 lower and accretion rates a factor of 22.5 lower than variable luminous AGNs at the same redshift. We find that an empirical model based on a universal broken power-law power spectral density function, where the break frequency depends on SMBH mass and accretion rate, roughly reproduces the shape, but not the normalization, of the variability-luminosity trends measured for variable galaxies and more luminous AGNs.

  12. VARIABILITY-SELECTED LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI IN THE 4 Ms CHANDRA DEEP FIELD-SOUTH

    International Nuclear Information System (INIS)

    The 4 Ms Chandra Deep Field-South (CDF-S) and other deep X-ray surveys have been highly effective at selecting active galactic nuclei (AGNs). However, cosmologically distant low-luminosity AGNs (LLAGNs) have remained a challenge to identify due to significant contribution from the host galaxy. We identify long-term X-ray variability (∼month-years, observed frame) in 20 of 92 CDF-S galaxies spanning redshifts z ≈ 0.08-1.02 that do not meet other AGN selection criteria. We show that the observed variability cannot be explained by X-ray binary populations or ultraluminous X-ray sources, so the variability is most likely caused by accretion onto a supermassive black hole (SMBH). The variable galaxies are not heavily obscured in general, with a stacked effective power-law photon index of Γstack ≈ 1.93 ± 0.13, and are therefore likely LLAGNs. The LLAGNs tend to lie a factor of ≈6-80 below the extrapolated linear variability-luminosity relation measured for luminous AGNs. This may be explained by their lower accretion rates. Variability-independent black hole mass and accretion-rate estimates for variable galaxies show that they sample a significantly different black hole mass-accretion-rate space, with masses a factor of 2.4 lower and accretion rates a factor of 22.5 lower than variable luminous AGNs at the same redshift. We find that an empirical model based on a universal broken power-law power spectral density function, where the break frequency depends on SMBH mass and accretion rate, roughly reproduces the shape, but not the normalization, of the variability-luminosity trends measured for variable galaxies and more luminous AGNs.

  13. Galaxies with a Central Minimum in Stellar Luminosity Density

    CERN Document Server

    Lauer, T R; Richstone, D O; Tremaine, S; Bender, R; Bower, G; Dressler, A; Faber, S M; Filippenko, A V; Green, R; Grillmair, C J; Ho, L C; Kormendy, J; Magorrian, J; Pinkney, J C; Laine, S; Postman, M; Van der Marel, R P; Lauer, Tod R.; Gebhardt, Karl; Richstone, Douglas; Tremaine, Scott; Bender, Ralf; Bower, Gary; Dressler, Alan; Filippenko, Alexei V.; Green, Richard; Grillmair, Carl J.; Ho, Luis C.; Kormendy, John; Magorrian, John; Pinkney, Jason; Postman, Marc; Marel, Roeland P. van der

    2002-01-01

    We used HST WFPC2 images to identify six early-type galaxies with surface- brightness profiles that decrease inward over a limited range of radii near their centers. The implied luminosity density profiles of these galaxies have local minima interior to their core break radii. NGC 3706 harbors a high surface brightness ring of starlight with radius ~20 pc. Its central structure may be related to that in the double-nucleus galaxies M31 and NGC 4486B. NGC 4406 and NGC 6876 have nearly flat cores that on close inspection are centrally depressed. Colors for both galaxies imply that this is not due to dust absorption. The surface brightness distributions of both galaxies are consistent with stellar tori that are more diffuse than the sharply defined system in NGC 3706. The remaining three galaxies are the brightest cluster galaxies in A260, A347, and A3574. Color information is not available for these objects, but they strongly resemble NGC 4406 and NGC 6876 in their cores. The thin ring in NGC 3706 may have forme...

  14. The Luminosity Function of Star Clusters in Spiral Galaxies

    CERN Document Server

    Larsen, S S

    2002-01-01

    Star clusters in 6 nearby spiral galaxies are examined using archive images from HST/WFPC2. The galaxies have previously been studied from the ground and some of them are known to possess rich populations of "young massive clusters" (YMCs). Comparison with the HST images indicates a success-rate of about 75% for the ground-based cluster detections, with typical contaminants being blends or loose groupings of several stars in crowded regions. The luminosity functions (LFs) of cluster candidates identified on the HST images are analyzed and compared with existing data for the Milky Way and the LMC. The LFs are well approximated by power-laws of the form dN(L)/dL ~ L^alpha, with slopes in the range -2.4

  15. High-luminosity LHC prospects with the upgraded ATLAS detector

    CERN Document Server

    Slawinska, Magdalena; The ATLAS collaboration

    2016-01-01

    Run-I at the LHC was very successful with the discovery of a new boson with properties compatible with those of the Higgs boson predicted by Standard Model. Precise measurements of the boson properties, and the discovery of physics beyond the Standard Model, are primary goals of the just restarted LHC running at 13 TeV collision energy and all future running at the LHC. The physics prospects with a pp centre-of-mass energy of 14 TeV are presented for 300 and 3000 fb-1 at the high-luminosity LHC. The ultimate precision attainable on measurements of the couplings of the 125 GeV boson to elementary fermions and bosons is discussed, as well as perspectives on the searches for partners associated with it. Supersymmetry is one of the best motivated extensions of the Standard Model. The current searches at the LHC have yielded sensitivity to TeV scale gluinos and 1st and 2nd generation squarks, as well as to 3rd generation squarks and electro-weakinos in the hundreds of GeV mass range. Benchmark studies are presente...

  16. Isochrones and Luminosity Functions for Old White Dwarfs

    CERN Document Server

    Richer, H B; Limongi, M; Chieffi, A; Straniero, O; Fahlman, G G; Richer, Harvey B.; Hansen, Brad; Limongi, Marco; Chieffi, Alessandro; Straniero, Oscar; Fahlman, Gregory G.

    1999-01-01

    Using a new grid of models of cooling white dwarfs, we calculate isochrones and luminosity functions in the Johnson-Kron/Cousins and HST filter sets for systems containing old white dwarfs. These new models incorporate a non-grey atmosphere which is necessary to properly describe the effects of molecular opacity at the cool temperatures of old white dwarfs. The various functions calculated and extensively tabulated and plotted are meant to be as utilitarian as possible for observers so all results are listed in quantities that observers will obtain. The tables and plots developed should eventually prove critical in interpreting the results of HST's Advanced Camera observations of the oldest white dwarfs in nearby globular clusters, in understanding the results of searches for old white dwarfs in the Galactic halo, and in determining ages for star clusters of all ages using white dwarfs. As a practical application we demonstrate the use of these results by deriving the white dwarf cooling age of the old Galact...

  17. ESTIMATING LUMINOSITY FUNCTION CONSTRAINTS FROM HIGH-REDSHIFT GALAXY SURVEYS

    International Nuclear Information System (INIS)

    The installation of the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) will revolutionize the study of high-redshift galaxy populations. Initial observations of the HST Ultra Deep Field (UDF) have yielded multiple z ?> 7 dropout candidates. Supplemented by the GOODS Early Release Science (ERS) and further UDF pointings, these data will provide crucial information about the most distant known galaxies. However, achieving tight constraints on the z ? 7 galaxy luminosity function (LF) will require even more ambitious photometric surveys. Using a Fisher matrix approach to fully account for Poisson and cosmic sample variance, as well as covariances in the data, we estimate the uncertainties on LF parameters achieved by surveys of a given area and depth. Applying this method to WFC3 z ? 7 dropout galaxy samples, we forecast the LF parameter uncertainties for a variety of model surveys. We demonstrate that performing a wide area (?1 deg2) survey to HAB ? 27 depth or increasing the UDF depth to HAB ? 30 provides excellent constraints on the high-z LF when combined with the existing Ultradeep Field Guest Observation and GOODS ERS data. We also show that the shape of the matter power spectrum may limit the possible gain of splitting wide area (?>0.5 deg2) high-redshift surveys into multiple fields to probe statistically independent regions; the increased rms density fluctuations in smaller volumes mostly offset the improved variance gained from independent samples.

  18. Jet and disk luminosities in tidal disruption events

    CERN Document Server

    Piran, Tsvi; Tchekhovskoy, Alexander

    2015-01-01

    Tidal disruption events (TDE) in which a star is devoured by a massive black hole at a galac- tic center pose a challenge to our understanding of accretion processes. Within a month the accretion rate reaches super-Eddington levels. It then drops gradually over a time scale of a year to sub-Eddington regimes. The initially geometrically thick disk becomes a thin one and eventually an ADAF at very low accretion rates. As such, TDEs explore the whole range of accretion rates and configurations. A challenging question is what the corresponding light curves of these events are. We explore numerically the disk luminosity and the conditions within the inner region of the disk using a fully general relativistic slim disk model. Those conditions determine the magnitude of the magnetic field that engulfs the black hole and this, in turn, determines the Blandford-Znajek jet power. We estimate this power in two different ways and show that they are self-consistent. We find, as expected earlier from analytic argu- ments ...

  19. Luminosity measurements with the LUCID detector in the ATLAS experiment

    CERN Document Server

    Valentinetti, Sara

    La misura della luminosità è un obiettivo importante per tutta la fisica del modello standard e per la scoperta di nuova fisica, poiché è legata alla sezione d'urto (σ) e al rate di produzione (R) di un determinato processo dalla relazione L = R*σ. Nell'eserimento ATLAS a LHC è installato un monitor di luminosità dedicato chiamato LUCID (Luminosity measurements Using Cherenkov Integrating Detector). Grazie ai dati acquisiti durante il 2010 la valutazione off-line delle performances del LUCID e l'implementazione di controlli on-line sulla qualità dei dati raccolti è stata possibile. I dati reali sono stati confrontati con i dati Monte Carlo e le simulazioni sono state opportunamente aggiustate per ottimizzare l'accordo tra i due. La calibrazione della luminosità relativa che permette di ottenere una valutazione della luminosità assoluta è stata possibile grazie ai cosiddetti Van der Meer scan, grazie ai quale è stata ottenuta una precisione dell'11%. L'analisi della fisica del decadimento della Z...

  20. Galaxy and Mass Assembly (GAMA): ugriz galaxy luminosity functions

    CERN Document Server

    Loveday, J; Baldry, I K; Driver, S P; Hopkins, A M; Peacock, J A; Bamford, S P; Liske, J; Bland-Hawthorn, J; Brough, S; Brown, M J I; Cameron, E; Conselice, C J; Croom, S M; Frenk, C S; Gunawardhana, M; Hill, D T; Jones, D H; Kelvin, L S; Kuijken, K; Nichol, R C; Parkinson, H R; Phillipps, S; Pimbblet, K A; Popescu, C C; Prescott, M; Robotham, A S G; Sharp, R G; Sutherland, W J; Taylor, E N; Thomas, D; Tuffs, R J; van Kampen, E; Wijesinghe, D

    2011-01-01

    Galaxy and Mass Assembly (GAMA) is a project to study galaxy formation and evolution, combining imaging data from ultraviolet to radio with spectroscopic data from the AAOmega spectrograph on the Anglo-Australian Telescope. Using data from phase 1 of GAMA, taken over three observing seasons, and correcting for various minor sources of incompleteness, we calculate galaxy luminosity functions (LFs) and their evolution in the ugriz passbands. At low redshift, z < 0.1, we find that blue galaxies, defined according to a magnitude-dependent but non-evolving colour cut, are reasonably well fit over a range of more than ten magnitudes by simple Schechter functions in all bands. Red galaxies, and the combined blue-plus-red sample, require double power-law Schechter functions to fit a dip in their LF faintward of the characteristic magnitude M* before a steepening faint end. This upturn is at least partly due to dust-reddened disk galaxies. We measure evolution of the galaxy LF over the redshift range 0.002 < z &...

  1. EVN observations of low-luminosity flat-spectrum AGNs

    CERN Document Server

    Caccianiga, A; Thean, A; Dennett-Thorpe, J

    2001-01-01

    We present and discuss the results of VLBI (EVN) observations of three low-luminosity (P(5 GHz)<10^25 W/Hz) Broad Emission Line AGNs carefully selected from a sample of flat spectrum radio sources (CLASS). Based on the total and the extended radio power at 5 GHz and at 1.4 GHz respectively, these objects should be technically classified as radio-quiet AGN and thus the origin of their radio emission is not clearly understood. The VLBI observations presented in this paper have revealed compact radio cores which imply a lower limit on the brightness temperature of about 3X10^8 K. This result rules out a thermal origin for the radio emission and strongly suggests an emission mechanism similar to that observed in more powerful radio-loud AGNs. Since, by definition, the three objects show a flat (or inverted) radio spectrum between 1.4 GHz and 8.4 GHz, the observed radio emission could be relativistically beamed. Multi-epoch VLBI observations can confirm this possibility in two years time.

  2. The slope of the GRB Variability/Peak Luminosity Correlation

    CERN Document Server

    Guidorzi, C; Montanari, E; Rossi, F; Amati, L; Gomboc, A; Mundell, C G

    2006-01-01

    From a sample of 32 GRBs with known redshift (Guidorzi et al. 2005) and then a sample of 551 BATSE GRBs with derived pseudo-redshift (Guidorzi 2005), the time variability/peak luminosity correlation (V vs. L) found by Reichart et al. (2001) was tested. For both samples the correlation is still found but less relevant due to a much higher spread of the data. Assuming a straight line in the logL-logV plane (logL = m logV + b), as done by Reichart et al., the slope was found lower than that derived by Reichart et al.: m = 1.3_{-0.4}^{+0.8} (Guidorzi et al. 2005), m = 0.85 +- 0.02 (Guidorzi 2005), to be compared with m = 3.3^{+1.1}_{-0.9} (Reichart et al. 2001). Reichart & Nysewander (2005) attribute the different slope to the fact we do not take into account in the fit the variance of the sample, and demonstrate that, using the method by Reichart (2001), the data set of Guidorzi et al. (2005) in logL-logV plane is still well described with slope m = 3.4^{+0.9}_{-0.6}. Here we compare the results of two metho...

  3. Estimating Luminosity Function Constraints from High-Redshift Galaxy Surveys

    CERN Document Server

    Robertson, Brant E

    2010-01-01

    The installation of the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) will revolutionize the study of high-redshift galaxy populations. Initial observations of the HST Ultra Deep Field (UDF) have yielded multiple z>~7 dropout candidates. Supplemented by the Great Observatory Origins Deep Survey (GOODS) Early Release Science (ERS) and further UDF pointings, these data will provide crucial information about the most distant known galaxies. However, achieving tight constraints on the z~7 galaxy luminosity function (LF) will require even more ambitious photometric surveys. Using a Fisher matrix approach to fully account for Poisson and cosmic sample variance, as well as covariances in the data, we estimate the uncertainties on LF parameters achieved by surveys of a given area and depth. Applying this method to WFC3 z~7 dropout galaxy samples, we forecast the LF parameter uncertainties for a variety of model surveys. We demonstrate that performing a wide area (~1 deg^2) survey to H_AB~27 depth or ...

  4. The dust grain size - stellar luminosity trend in debris discs

    CERN Document Server

    Pawellek, Nicole

    2015-01-01

    The cross section of material in debris discs is thought to be dominated by the smallest grains that can still stay in bound orbits despite the repelling action of stellar radiation pressure. Thus the minimum (and typical) grain size $s_\\text{min}$ is expected to be close to the radiation pressure blowout size $s_\\text{blow}$. Yet a recent analysis of a sample of Herschel-resolved debris discs showed the ratio $s_\\text{min}/s_\\text{blow}$ to systematically decrease with the stellar luminosity from about ten for solar-type stars to nearly unity in the discs around the most luminous A-type stars. Here we explore this trend in more detail, checking how significant it is and seeking to find possible explanations. We show that the trend is robust to variation of the composition and porosity of dust particles. For any assumed grain properties and stellar parameters, we suggest a recipe of how to estimate the "true" radius of a spatially unresolved debris disc, based solely on its spectral energy distribution. The r...

  5. On the luminosity distance and the epoch of acceleration

    CERN Document Server

    Sutherland, Will

    2015-01-01

    Standard cosmological models based on general relativity (GR) with dark energy predict that the Universe underwent a transition from decelerating to accelerating expansion at a moderate redshift $z_{acc} \\sim 0.7$. Clearly, it is of great interest to directly measure this transition in a model-independent way, without the assumption that GR is the correct theory of gravity. We explore to what extent supernova (SN) luminosity distance measurements provide evidence for such a transition: we show that, contrary to intuition, the well-known "turnover" in the SN distance residuals $\\Delta\\mu$ relative to an empty (Milne) model does not give firm evidence for such a transition within the redshift range spanned by SN data. The observed turnover in that diagram is predominantly due to the negative curvature in the Milne model, {\\em not} the deceleration predicted by $\\Lambda$CDM and relatives. We show that there are several advantages in plotting distance residuals against a flat, non-accelerating model $(w = -1/3)$,...

  6. The Luminosity Function of Low-Redshift Abell Galaxy Clusters

    CERN Document Server

    Barkhouse, Wayne A; López-Cruz, Omar

    2007-01-01

    We present the results from a survey of 57 low-redshift Abell galaxy clusters to study the radial dependence of the luminosity function (LF). The dynamical radius of each cluster, r200, was estimated from the photometric measurement of cluster richness, Bgc. The shape of the LFs are found to correlate with radius such that the faint-end slope, alpha, is generally steeper on the cluster outskirts. The sum of two Schechter functions provides a more adequate fit to the composite LFs than a single Schechter function. LFs based on the selection of red and blue galaxies are bimodal in appearance. The red LFs are generally flat for -22 -18. The blue LFs contain a larger contribution from faint galaxies than the red LFs. The blue LFs have a rising faint-end component (alpha ~ -1.7) for M_Rc > -21, with a weaker dependence on radius than the red LFs. The dispersion of M* was determined to be 0.31 mag, which is comparable to the median measurement uncertainty of 0.38 mag. This suggests that the bright-end of the LF is...

  7. On the luminosity distance and the epoch of acceleration

    Science.gov (United States)

    Sutherland, Will; Rothnie, Paul

    2015-02-01

    Standard cosmological models based on general relativity (GR) with dark energy predict that the Universe underwent a transition from decelerating to accelerating expansion at a moderate redshift zacc ˜ 0.7. Clearly, it is of great interest to directly measure this transition in a model-independent way, without the assumption that GR is the correct theory of gravity. We explore to what extent supernova (SN) luminosity distance measurements provide evidence for such a transition: we show that, contrary to intuition, the well-known `turnover' in the SN distance residuals Δμ relative to an empty (Milne) model does not give firm evidence for such a transition within the redshift range spanned by SN data. The observed turnover in that diagram is predominantly due to the negative curvature in the Milne model, not the deceleration predicted by Λ cold dark matter and relatives. We show that there are several advantages in plotting distance residuals against a flat, non-accelerating model (w = -1/3), and also remapping the z-axis to u = ln (1 + z); we outline a number of useful and intuitive properties of this presentation. We conclude that there are significant complementarities between SNe and baryon acoustic oscillations (BAOs): SNe offer high precision at low redshifts and give good constraints on the net amount of acceleration since z ˜ 0.7, but are weak at constraining zacc; while radial BAO measurements are probably superior for placing direct constraints on zacc.

  8. Luminosity Functions of Spitzer-identified Protostars in Nine Nearby Molecular Clouds

    Science.gov (United States)

    Kryukova, E.; Megeath, S. T.; Gutermuth, R. A.; Pipher, J.; Allen, T. S.; Allen, L. E.; Myers, P. C.; Muzerolle, J.

    2012-08-01

    We identify protostars in Spitzer surveys of nine star-forming (SF) molecular clouds within 1 kpc: Serpens, Perseus, Ophiuchus, Chamaeleon, Lupus, Taurus, Orion, Cep OB3, and Mon R2, which combined host over 700 protostar candidates. These clouds encompass a variety of SF environments, including both low-mass and high-mass SF regions, as well as dense clusters and regions of sparsely distributed star formation. Our diverse cloud sample allows us to compare protostar luminosity functions in these varied environments. We combine near- and mid-infrared photometry from the Two Micron All Sky Survey and Spitzer to create 1-24 ?m spectral energy distributions (SEDs). Using protostars from the c2d survey with well-determined bolometric luminosities, we derive a relationship between bolometric luminosity, mid-IR luminosity (integrated from 1-24 ?m), and SED slope. Estimations of the bolometric luminosities for protostar candidates are combined to create luminosity functions for each cloud. Contamination due to edge-on disks, reddened Class II sources, and galaxies is estimated and removed from the luminosity functions. We find that luminosity functions for high-mass SF clouds (Orion, Mon R2, and Cep OB3) peak near 1 L ? and show a tail extending toward luminosities above 100 L ?. The luminosity functions of the low-mass SF clouds (Serpens, Perseus, Ophiuchus, Taurus, Lupus, and Chamaeleon) do not exhibit a common peak, however the combined luminosity function of these regions peaks below 1 L ?. Finally, we examine the luminosity functions as a function of the local surface density of young stellar objects. In the Orion molecular clouds, we find a significant difference between the luminosity functions of protostars in regions of high and low stellar density, the former of which is biased toward more luminous sources. This may be the result of primordial mass segregation, although this interpretation is not unique. We compare our luminosity functions to those predicted by models and find that our observed luminosity functions are best matched by models that invoke competitive accretion, although we do not find strong agreement between the high-mass SF clouds and any of the models.

  9. LUMINOSITY FUNCTIONS OF SPITZER-IDENTIFIED PROTOSTARS IN NINE NEARBY MOLECULAR CLOUDS

    International Nuclear Information System (INIS)

    We identify protostars in Spitzer surveys of nine star-forming (SF) molecular clouds within 1 kpc: Serpens, Perseus, Ophiuchus, Chamaeleon, Lupus, Taurus, Orion, Cep OB3, and Mon R2, which combined host over 700 protostar candidates. These clouds encompass a variety of SF environments, including both low-mass and high-mass SF regions, as well as dense clusters and regions of sparsely distributed star formation. Our diverse cloud sample allows us to compare protostar luminosity functions in these varied environments. We combine near- and mid-infrared photometry from the Two Micron All Sky Survey and Spitzer to create 1-24 ?m spectral energy distributions (SEDs). Using protostars from the c2d survey with well-determined bolometric luminosities, we derive a relationship between bolometric luminosity, mid-IR luminosity (integrated from 1-24 ?m), and SED slope. Estimations of the bolometric luminosities for protostar candidates are combined to create luminosity functions for each cloud. Contamination due to edge-on disks, reddened Class II sources, and galaxies is estimated and removed from the luminosity functions. We find that luminosity functions for high-mass SF clouds (Orion, Mon R2, and Cep OB3) peak near 1 L? and show a tail extending toward luminosities above 100 L?. The luminosity functions of the low-mass SF clouds (Serpens, Perseus, Ophiuchus, Taurus, Lupus, and Chamaeleon) do not exhibit a common peak, however the combined luminosity function of these regions peaks below 1 L?. Finally, we examine the luminosity functions as a function of the local surface density of young stellar objects. In the Orion molecular clouds, we find a significant difference between the luminosity functions of protostars in regions of high and low stellar density, the former of which is biased toward more luminous sources. This may be the result of primordial mass segregation, although this interpretation is not unique. We compare our luminosity functions to those predicted by models and find that our observed luminosity functions are best matched by models that invoke competitive accretion, although we do not find strong agreement between the high-mass SF clouds and any of the models.

  10. LUMINOSITY FUNCTIONS OF SPITZER-IDENTIFIED PROTOSTARS IN NINE NEARBY MOLECULAR CLOUDS

    Energy Technology Data Exchange (ETDEWEB)

    Kryukova, E.; Megeath, S. T.; Allen, T. S. [Department of Physics and Astronomy, University of Toledo, Toledo, OH (United States); Gutermuth, R. A. [Department of Astronomy, University of Massachusetts, Amherst, MA (United States); Pipher, J. [Department of Physics and Astronomy, University of Rochester, Rochester, NY (United States); Allen, L. E. [National Optical Astronomy Observatories, Tucson, AZ (United States); Myers, P. C. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Muzerolle, J. [Space Telescope Science Institute, Baltimore, MD (United States)

    2012-08-15

    We identify protostars in Spitzer surveys of nine star-forming (SF) molecular clouds within 1 kpc: Serpens, Perseus, Ophiuchus, Chamaeleon, Lupus, Taurus, Orion, Cep OB3, and Mon R2, which combined host over 700 protostar candidates. These clouds encompass a variety of SF environments, including both low-mass and high-mass SF regions, as well as dense clusters and regions of sparsely distributed star formation. Our diverse cloud sample allows us to compare protostar luminosity functions in these varied environments. We combine near- and mid-infrared photometry from the Two Micron All Sky Survey and Spitzer to create 1-24 {mu}m spectral energy distributions (SEDs). Using protostars from the c2d survey with well-determined bolometric luminosities, we derive a relationship between bolometric luminosity, mid-IR luminosity (integrated from 1-24 {mu}m), and SED slope. Estimations of the bolometric luminosities for protostar candidates are combined to create luminosity functions for each cloud. Contamination due to edge-on disks, reddened Class II sources, and galaxies is estimated and removed from the luminosity functions. We find that luminosity functions for high-mass SF clouds (Orion, Mon R2, and Cep OB3) peak near 1 L{sub Sun} and show a tail extending toward luminosities above 100 L{sub Sun }. The luminosity functions of the low-mass SF clouds (Serpens, Perseus, Ophiuchus, Taurus, Lupus, and Chamaeleon) do not exhibit a common peak, however the combined luminosity function of these regions peaks below 1 L{sub Sun }. Finally, we examine the luminosity functions as a function of the local surface density of young stellar objects. In the Orion molecular clouds, we find a significant difference between the luminosity functions of protostars in regions of high and low stellar density, the former of which is biased toward more luminous sources. This may be the result of primordial mass segregation, although this interpretation is not unique. We compare our luminosity functions to those predicted by models and find that our observed luminosity functions are best matched by models that invoke competitive accretion, although we do not find strong agreement between the high-mass SF clouds and any of the models.

  11. Lightning current and luminosity at and above channel bottom for return strokes and M-components

    Science.gov (United States)

    Carvalho, F. L.; Uman, M. A.; Jordan, D. M.; Ngin, T.

    2015-10-01

    We measured current and luminosity at the channel bottom of 12 triggered lightning discharges including 44 return strokes, 23 M-components, and 1 initial continuous current pulse. Combined current and luminosity data for impulse currents span a 10-90% risetime range from 0.15 to 192 s. Current risetime and luminosity risetime at the channel bottom are roughly linearly correlated (?r,I = 0.71?r,L1.08). We observed a time delay between current and the resultant luminosity at the channel bottom, both measured at 20% of peak amplitude, that is approximately linearly related to both the luminosity 10-90% risetime (?t20,b = 0.24?r,L1.12) and the current 10-90% risetime (?t20,b = 0.35?r,I1.03). At the channel bottom, the peak current is roughly proportional to the square root of the peak luminosity (IP = 21.89LP0.57) over the full range of current and luminosity risetimes. For two return strokes we provide measurements of stroke luminosity vs. time for 11 increasing heights to 115 m altitude. We assume that measurements above the channel bottom behave similarly to those at the bottom and find that (1) one return stroke current peak decayed at 115 m to about 47% of its peak value at channel bottom, while the luminosity peak at 115 m decayed to about 20%, and for the second stroke 38% and 12%, respectively; and (2) measured upward return stroke luminosity speeds of the two strokes of 1.10 108 and 9.7 107 ms-1 correspond to current speeds about 30% faster. These results represent the first determination of return stroke current speed and current peak value above ground derived from measured return stroke luminosity data.

  12. Dependences of the X-ray luminosity and pulsar wind nebula on different parameters of pulsars and the evolutionary effects

    CERN Document Server

    Guseinov, O H; Tagieva, S O; Taskin, M O

    2004-01-01

    Dependences of the X-ray luminosity (L$_x$) of single pulsars, due to ejection of relativistic particles, on electric field intensity, rate of rotational energy loss (\\.{E}), magnetic field, period, and the energy spectra of the ejected particles are discussed. Influence of the magnetic field and effects of some other parameters of neutron stars on the L$_x$-\\.{E} and the L$_x$-$\\tau$ (characteristic time) dependences are considered. Evolutionary factors also play an important role in our considerations. We find that only the pulsars with L$_{2-10keV}

  13. THE DEMOGRAPHICS OF BROAD-LINE QUASARS IN THE MASS-LUMINOSITY PLANE. I. TESTING FWHM-BASED VIRIAL BLACK HOLE MASSES

    International Nuclear Information System (INIS)

    We jointly constrain the luminosity function (LF) and black hole mass function (BHMF) of broad-line quasars with forward Bayesian modeling in the quasar mass-luminosity plane, based on a homogeneous sample of ∼58, 000 Sloan Digital Sky Survey (SDSS) Data Release 7 quasars at z ∼ 0.3-5. We take into account the selection effect of the sample flux limit; more importantly, we deal with the statistical scatter between true BH masses and FWHM-based single-epoch virial mass estimates, as well as potential luminosity-dependent biases of these mass estimates. The LF is tightly constrained in the regime sampled by SDSS and makes reasonable predictions when extrapolated to ∼3 mag fainter. Downsizing is seen in the model LF. On the other hand, we find it difficult to constrain the BHMF to within a factor of a few at z ∼> 0.7 (with Mg II and C IV-based virial BH masses). This is mainly driven by the unknown luminosity-dependent bias of these mass estimators and its degeneracy with other model parameters, and secondly driven by the fact that SDSS quasars only sample the tip of the active BH population at high redshift. Nevertheless, the most likely models favor a positive luminosity-dependent bias for Mg II and possibly for C IV, such that at fixed true BH mass, objects with higher-than-average luminosities have overestimated FWHM-based virial masses. There is tentative evidence that downsizing also manifests itself in the active BHMF, and the BH mass density in broad-line quasars contributes an insignificant amount to the total BH mass density at all times. Within our model uncertainties, we do not find a strong BH mass dependence of the mean Eddington ratio, but there is evidence that the mean Eddington ratio (at fixed BH mass) increases with redshift.

  14. The Demographics of Broad-line Quasars in the Mass-Luminosity Plane. I. Testing FWHM-based Virial Black Hole Masses

    Science.gov (United States)

    Shen, Yue; Kelly, Brandon C.

    2012-02-01

    We jointly constrain the luminosity function (LF) and black hole mass function (BHMF) of broad-line quasars with forward Bayesian modeling in the quasar mass-luminosity plane, based on a homogeneous sample of ~58, 000 Sloan Digital Sky Survey (SDSS) Data Release 7 quasars at z ~ 0.3-5. We take into account the selection effect of the sample flux limit; more importantly, we deal with the statistical scatter between true BH masses and FWHM-based single-epoch virial mass estimates, as well as potential luminosity-dependent biases of these mass estimates. The LF is tightly constrained in the regime sampled by SDSS and makes reasonable predictions when extrapolated to ~3 mag fainter. Downsizing is seen in the model LF. On the other hand, we find it difficult to constrain the BHMF to within a factor of a few at z >~ 0.7 (with Mg II and C IV-based virial BH masses). This is mainly driven by the unknown luminosity-dependent bias of these mass estimators and its degeneracy with other model parameters, and secondly driven by the fact that SDSS quasars only sample the tip of the active BH population at high redshift. Nevertheless, the most likely models favor a positive luminosity-dependent bias for Mg II and possibly for C IV, such that at fixed true BH mass, objects with higher-than-average luminosities have overestimated FWHM-based virial masses. There is tentative evidence that downsizing also manifests itself in the active BHMF, and the BH mass density in broad-line quasars contributes an insignificant amount to the total BH mass density at all times. Within our model uncertainties, we do not find a strong BH mass dependence of the mean Eddington ratio, but there is evidence that the mean Eddington ratio (at fixed BH mass) increases with redshift.

  15. Electron-electron luminosity in the Next Linear Collider -- a preliminary study

    International Nuclear Information System (INIS)

    In this paper, the authors discuss some operational aspects of electron-electron collisions at the Next Linear Collider (NLC) and estimate the luminosity attainable in such a machine. They also consider the use of two future technologies which could simplify the operation and improve the luminosity in an e-e- collider: polarized rf guns and plasma lenses

  16. Period--luminosity--color relations and pulsation modes of pulsating variable stars

    International Nuclear Information System (INIS)

    The periods of delta Scuti, RR Lyrae, dwarf Cepheid, and W Virginis variables have been investigated for their dependence on luminosity, color, mass, and pulsation modes. A maximum-likelihood method, which includes consideration of the observational errors in each coordinate, has been applied to obtain observational period-luminosity-color (P-L-C) relations

  17. Performance of the BGO luminosity monitor of the CMD-2 detector

    International Nuclear Information System (INIS)

    The luminosity monitor of the VEPP-2M collider at the CMD-2 detector is described. The monitor consists of two identical total absorption counters based on 9 X0 BGO crystal with phototriode readout. Double bremsstrahlung events are used for luminosity measurement. (orig.)

  18. Far-infrared luminosities of Markarian starburst galaxies. II - Individual galaxies

    Science.gov (United States)

    Deutsch, L. K.; Willner, S. P.

    1987-04-01

    IRAS observations of galaxies in the Balzano sample of optically selected starburst nuclei and of a comparison of Virgo spiral galaxies are used to derive far-infrared luminosities. Distances and blue and H? luminosities of the starburst galaxies are also tabulated.

  19. Far-infrared and accretion luminosities of the present-day active galactic nuclei

    CERN Document Server

    Matsuoka, Kenta

    2015-01-01

    We investigate the relation between star formation (SF) and black hole accretion luminosities, using a sample of 492 type-2 active galactic nuclei (AGNs) at z < 0.22, which are detected in the far-infrared (FIR) surveys with AKARI and Herschel. We adopt FIR luminosities at 90 and 100 um as SF luminosities, assuming the proposed linear proportionality of star formation rate with FIR luminosities. By estimating AGN luminosities from [OIII]5007 and [OI]6300 emission lines, we find a positive linear trend between FIR and AGN luminosities over a wide dynamical range. This result appears to be inconsistent with the recent reports that low-luminosity AGNs show essentially no correlation between FIR and X-ray luminosities, while the discrepancy is likely due to the Malmquist and sample selection biases. By analyzing the spectral energy distribution, we find that pure-AGN candidates, of which FIR radiation is thought to be AGN-dominated, show significantly low-SF activities. These AGNs hosted by low-SF galaxies are...

  20. The Relationship between Radio Luminosity and Core-Dominance Parameter for XBLs

    Indian Academy of Sciences (India)

    Yong-Xiang Wang; Y. Liu; Fei-Peng Pi; Jiang-He Yang

    2011-03-01

    In this work, we investigate the correlation between the luminosity and the core-dominance parameter for a sample of X-ray selected BL Lacertae objects (XBLs), and found that the extended luminosity is strongly anti-correlated with the core-dominance parameter while the core (or the total) luminosity is not correlated with the core-dominance parameter. If this is the case, then we can expect that the lower extended luminosity XBLs and their core luminosity is relatively higher. This can be explained by a relativistic beaming model since in this case, the viewing angle is smaller and the emissions dominate the extended emissions. Therefore, the anti-correlation is in fact the result of the relativistic beaming model.

  1. Galaxy luminosity function and Tully-Fisher relation: reconciled through rotation-curve studies

    Energy Technology Data Exchange (ETDEWEB)

    Cattaneo, Andrea [Laboratoire d' Astrophysique de Marseille, UMR 6110 CNRS, Universite d' Aix-Marseille, 38 Rue F. Joliot-Curie, F-13388 Marseille Cedex 13 (France); Salucci, Paolo [Department of Astrophysics, SISSA, Via Beirut, 2-4, I-34014 Trieste (Italy); Papastergis, Emmanouil, E-mail: andrea.cattaneo@oamp.fr, E-mail: salucci@sissa.it, E-mail: papastergis@astro.cornell.edu [Center for Radiophysics and Space Research, Space Sciences Building, Cornell University, Ithaca, NY 14853 (United States)

    2014-03-10

    The relation between galaxy luminosity L and halo virial velocity v {sub vir} required to fit the galaxy luminosity function differs from the observed Tully-Fisher relation between L and disk speed v {sub rot}. Because of this, the problem of reproducing the galaxy luminosity function and the Tully-Fisher relation simultaneously has plagued semianalytic models since their inception. Here we study the relation between v {sub rot} and v {sub vir} by fitting observational average rotation curves of disk galaxies binned in luminosity. We show that the v {sub rot}-v {sub vir} relation that we obtain in this way can fully account for this seeming inconsistency. Therefore, the reconciliation of the luminosity function with the Tully-Fisher relation rests on the complex dependence of v {sub rot} on v {sub vir}, which arises because the ratio of stellar mass to dark matter mass is a strong function of halo mass.

  2. Galaxy Luminosity Function and Tully-Fisher Relation: Reconciled through Rotation-curve Studies

    Science.gov (United States)

    Cattaneo, Andrea; Salucci, Paolo; Papastergis, Emmanouil

    2014-03-01

    The relation between galaxy luminosity L and halo virial velocity v vir required to fit the galaxy luminosity function differs from the observed Tully-Fisher relation between L and disk speed v rot. Because of this, the problem of reproducing the galaxy luminosity function and the Tully-Fisher relation simultaneously has plagued semianalytic models since their inception. Here we study the relation between v rot and v vir by fitting observational average rotation curves of disk galaxies binned in luminosity. We show that the v rot-v vir relation that we obtain in this way can fully account for this seeming inconsistency. Therefore, the reconciliation of the luminosity function with the Tully-Fisher relation rests on the complex dependence of v rot on v vir, which arises because the ratio of stellar mass to dark matter mass is a strong function of halo mass.

  3. Galaxy luminosity function and Tully-Fisher relation: reconciled through rotation-curve studies

    CERN Document Server

    Cattaneo, Andrea; Papastergis, Emmanouil

    2014-01-01

    The relation between galaxy luminosity L and halo virial velocity v_vir required to fit the galaxy luminosity function differs from the observed Tully-Fisher relation between L and disc speed v_rot. Hence the problem of reproducing the galaxy luminosity function and the Tully-Fisher relation simultaneously has plagued semianalytic models since their inception. Here we study the relation between v_rot and v_vir by fitting observational average rotation curves of disc galaxies binned in luminosity. We show that the v_rot - v_vir relation that we obtain in this way can fully account for this seeming inconsistency. Therefore, the reconciliation of the luminosity function with the Tully-Fisher relation rests on the complex dependence of v_rot on v_vir, which arises because the ratio of stellar mass to dark matter mass is a strong function of halo mass.

  4. Morphologies of low-redshift AGN host galaxies: what role does AGN luminosity play?

    CERN Document Server

    Villforth, Carolin; Koekemoer, Anton; Rosario, David; Hamilton, Timothy; McGrath, Elizabeth J; van der Wel, Arjen; Chang, YuYen; Guo, Yicheng

    2013-01-01

    Mergers of galaxies have been suspected to be a major trigger of AGN activity for many years. However, when compared to carefully matched control samples, AGN host galaxies often show no enhanced signs of interaction. A common explanation for this lack of observed association between AGN and mergers has often been that while mergers are of importance for triggering AGN, they only dominate at the very high luminosity end of the AGN population. In this study, we compare the morphologies of AGN hosts to a carefully matched control sample and particularly study the role of AGN luminosity. We find no enhanced merger rates in AGN hosts and also find no trend for stronger signs of disturbance at higher AGN luminosities. While this study does not cover very high luminosity AGN, we can exclude a strong connection between AGN and mergers over a wide range of AGN luminosities and therefore for a large part of the AGN population.

  5. Galaxy luminosity function and Tully-Fisher relation: reconciled through rotation-curve studies

    International Nuclear Information System (INIS)

    The relation between galaxy luminosity L and halo virial velocity v vir required to fit the galaxy luminosity function differs from the observed Tully-Fisher relation between L and disk speed v rot. Because of this, the problem of reproducing the galaxy luminosity function and the Tully-Fisher relation simultaneously has plagued semianalytic models since their inception. Here we study the relation between v rot and v vir by fitting observational average rotation curves of disk galaxies binned in luminosity. We show that the v rot-v vir relation that we obtain in this way can fully account for this seeming inconsistency. Therefore, the reconciliation of the luminosity function with the Tully-Fisher relation rests on the complex dependence of v rot on v vir, which arises because the ratio of stellar mass to dark matter mass is a strong function of halo mass.

  6. Infall-driven Protostellar Accretion and the Solution to the Luminosity Problem

    DEFF Research Database (Denmark)

    Padoan, Paolo; Haugbolle, Troels; Nordlund, Åke

    2014-01-01

    turbulent clouds are comparable to accretion rates inferred from protostellar luminosities or measured in pre-main-sequence stars. They should not be neglected in modeling the luminosity of protostars and the evolution of disks, even after the embedded protostellar phase. We find large variations of infall...... simulation reproduces well the observed characteristic values and scatter of protostellar luminosities and matches the observed protostellar luminosity function. The luminosity problem is therefore solved once realistic protostellar infall histories are accounted for, with no need for extreme accretion...... episodes. These results are based on a simulation of randomly driven magnetohydrodynamic turbulence on a scale of 4 pc, including self-gravity, adaptive-mesh refinement to a resolution of 50 AU, and accreting sink particles. The simulation yields a low star formation rate, consistent with the observations...

  7. Redetermination of the luminosity, distance, and reddening of Beta Lyrae

    International Nuclear Information System (INIS)

    We have redetermined the distance to β Lyrae and found that it probably lies between 345 and 400 pc, with the most likely value being 370 pc. With the corresponding true distance modulus of 7.8 mag, we find that the eclipsing system of β Lyrae has a maximum absolute visual magnitude of -4.7 mag. Using Wilson's model, we conclude that the average absolute visual magnitude of the primary component is -4.1 mag, so that the star is best classified as B8.5 or B9 II-Ib. The visual absolute magnitude of the secondary component is -3.3 mag, but this figure cannot be used to derive its luminosity, since that object has a nonstellar energy distribution. The color excess is small, E(B-V) = 0.04 mag. These data are based on our optical and IUE scans of the brightest visual companion to β Lyrae, HD 174664, and on an analysis of the hydrogen line profiles in its spectrum. We find that the star is mildly evolved within the main-sequence band. Its effective temperature (14 250 K) and surface gravity (log gapprox. =4.0) correspond most closely to those of stars classified as B6 V. This conclusion creates a certain evolutionary dilemma, since the age of HD 174664 should not exceed 20--30 million years if the basic model of β Lyrae as an Algol-type binary is correct, while our result is 48 x 106 yr. We address this problem at the end of the paper and conclude that the discrepancy may well be due to uncertainties in observational data and theoretical models and in the various calibrations involved. Nevertheless, attention should be paid to this potential age dilemma for β Lyrae

  8. Study on high rate MRPC for high luminosity experiments

    Science.gov (United States)

    Wang, Y.; Huang, X.; Lv, P.; Zhu, W.; Shi, L.; Xie, B.; Cheng, J.; Li, Y.

    2014-08-01

    Multi-gap Resistive Plate Chambers (MRPC) has been used to construct time-of-flight system in the field of nuclear and particle physics, due to their high-precision timing properties, high efficiency, reliability and coverage of large area. With the increase of accelerator luminosity, MRPCs have to withstand particle fluxes up to several tens of kHz/cm2 in view of the next generation physics experiments, such as the SIS-100/300 at FAIR-CBM, SoLID at JLab and NICA at JINR. But the MRPC assembled with float glass has very low rate capability not exceeding some hundreds of Hz/cm2. Two possible solutions for increasing rate capability, one is to reduce the bulk resistivity of glass and the other is to reduce the electrode thickness. Tsinghua University has done R&D on high rate MRPC for many years. A special low resistive glass with bulk resistivity around 1010Ω.cm was developed. We also studied the rate capability changes with glass thickness. In this paper we describe the performance of low resistive glass and two kinds of high rate MRPC (Pad readout and Strip readout) tested by deuterium beams. The results show that the tolerable particle flux can reach 70 kHz/cm2. In the mean time, MRPCs assembled with three thickness (0.7 mm, 0.5 mm and 0.35 mm) of float glass were also tested with deuteron beams, the results show that the three detectors can afford particle rate up to 500 Hz/cm2, 0.75 kHz/cm2 and 3 kHz/cm2, respectively.

  9. Study on high rate MRPC for high luminosity experiments

    International Nuclear Information System (INIS)

    Multi-gap Resistive Plate Chambers (MRPC) has been used to construct time-of-flight system in the field of nuclear and particle physics, due to their high-precision timing properties, high efficiency, reliability and coverage of large area. With the increase of accelerator luminosity, MRPCs have to withstand particle fluxes up to several tens of kHz/cm2 in view of the next generation physics experiments, such as the SIS-100/300 at FAIR-CBM, SoLID at JLab and NICA at JINR. But the MRPC assembled with float glass has very low rate capability not exceeding some hundreds of Hz/cm2. Two possible solutions for increasing rate capability, one is to reduce the bulk resistivity of glass and the other is to reduce the electrode thickness. Tsinghua University has done R and D on high rate MRPC for many years. A special low resistive glass with bulk resistivity around 1010Ω.cm was developed. We also studied the rate capability changes with glass thickness. In this paper we describe the performance of low resistive glass and two kinds of high rate MRPC (Pad readout and Strip readout) tested by deuterium beams. The results show that the tolerable particle flux can reach 70 kHz/cm2. In the mean time, MRPCs assembled with three thickness (0.7 mm, 0.5 mm and 0.35 mm) of float glass were also tested with deuteron beams, the results show that the three detectors can afford particle rate up to 500 Hz/cm2, 0.75 kHz/cm2 and 3 kHz/cm2, respectively

  10. SuperB: a Linear High-Luminosity B Factory

    Energy Technology Data Exchange (ETDEWEB)

    Albert, J.; Bettarini, S.; Biagini, M.; Bonneaud, G.; Cai, Y.; Calderini, G.; Ciuchini, M.; Dubois-Felsmann, G.P.; Ecklund, S.; Forti, F.; Gershon, T.J.; Giorgi, M.A.; Hitlin, D.G.; Leith, D.W.G.S.; Lusiani, A.; MacFarlane, D.B.; Martinez-Vidal, F.; Neri, N.; Novokhatski, A.; Pierini, M.; Piredda, G.; /Caltech /Pisa U. /Pisa, Scuola Normale

    2006-02-08

    This paper is based on the outcome of the activity that has taken place during the recent workshop on ''SuperB in Italy'' held in Frascati on November 11-12, 2005. The workshop was opened by a theoretical introduction of Marco Ciuchini and was structured in two working groups. One focused on the machine and the other on the detector and experimental issues.. The present status on CP is mainly based on the results achieved by BABAR and Belle. Establishment of the indirect CP violation in B sector in 2001 and of the direct CP violation in 2004 thanks to the success of PEP-II and KEKB e{sup +}e{sup -} asymmetric B Factories operating at the center of mass energy corresponding to the mass of the {Upsilon}(4S ). With the two B Factories taking data, the Unitarity Triangle is now beginning to be over constrained by improving the measurements of the sides and now also of the angles {alpha}, and {gamma}. We are also in presence of the very intriguing results about the measurements of sin2{beta} in the time dependent analysis of decay channels via penguin loops, where b {yields} s{bar s}s and b {yields} s{bar d}d. {tau} physics, in particular LFV search, as well as charm and ISR physics are important parts of the scientific program of a SuperB Factory. The physics case together with possible scenarios for the high luminosity SuperB Factory based on the concepts of the Linear Collider and the related experimental issues are discussed.

  11. L1Track: a fast Level 1 track trigger for the ATLAS High Luminosity Upgrade

    CERN Document Server

    Cerri, Alessandro

    2015-01-01

    With the planned high-luminosity upgrade of the LHC (HL-LHC), the ATLAS detector will see its collision rate increase by approximately a factor of 5 with respect to the current LHC operation. The earliest hardware based ATLAS trigger stage ("Level 1") will have to provide an higher rejection factor in a more difficult environment: a new improved Level 1 trigger architecture is under study, which includes the possibility of extracting with low latency and hight accuracy tracking information on time for the decision taking process. The expected trigger rates at HL-LHC and the available latency are the key ingredients that will drive the new design. The Level 1 track trigger (L1Track) design requires substantial modification of the ATLAS silicon detector readout philosophy: a precursor of the potential merging of detector and trigger architectures in the future silicon detectors at particle colliders. We will discuss potential approaches that are being actively considered to fulfil the demanding HL-LHC constrain...

  12. The Environmental Dependence of the Galaxy Luminosity Function in the ECO Survey

    Science.gov (United States)

    Andrews, Hayley; Andreas A. Berlind, Victor Calderon, Kathleen D. Eckert, Sheila J. Kannappan, Amanda J. Moffett, David V. Stark

    2016-01-01

    We study the environmental dependence of the galaxy luminosity function in the ECO survey and compare it with models that associate galaxies with dark matter halos. Specifically, we quantify the environment of each galaxy in the ECO survey using an Nth nearest neighbor distance metric, and we measure how the galaxy luminosity distribution varies from low density to high density environments. As expected, we find that luminous galaxies preferentially populate high density regions, while low luminosity galaxies preferentially populate lower density environments. We investigate whether this trend can be explained simply by the correlation of galaxy luminosity and dark matter halo mass combined with the environmental dependence of the halo mass function. In other words, we test the hypothesis that the luminosity of a galaxy depends solely on the mass of its dark matter halo and does not exhibit a residual dependence on the halo's larger environment. To test this hypothesis, we first construct mock ECO catalogs by populating dark matter halos in an N-body simulation with galaxies using a model that preserves the overall clustering strength of the galaxy population. We then assign luminosities to the mock galaxies using physically motivated models that connect luminosity to halo mass and are constrained to match the global ECO luminosity function. Finally, we impose the radial and angular selection functions of the ECO survey and repeat our environmental analysis on the mock catalogs. Though our mock catalog luminosity functions display similar qualitative trends as those from the ECO data, the trends are not in agreement quantitatively. Our results thus suggest that the simple models used to build the mocks are incomplete and that galaxy luminosity is possibly correlated with the larger scale density field.

  13. Ultra-faint ultraviolet galaxies at z ? 2 behind the lensing cluster A1689: The luminosity function, dust extinction, and star formation rate density

    Energy Technology Data Exchange (ETDEWEB)

    Alavi, Anahita; Siana, Brian; Freeman, William R.; Dominguez, Alberto [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Richard, Johan [Centre de Recherche Astrophysique de Lyon, Universit Lyon 1, 9 Avenue Charles Andr, F-69561 Saint Genis Laval Cedex (France); Stark, Daniel P.; Robertson, Brant [Department of Astronomy, Steward Observatory, University of Arizona, 933 North Cherry Avenue, Rm N204, Tucson, AZ 85721 (United States); Scarlata, Claudia [Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, MN 55455 (United States); Teplitz, Harry I.; Rafelski, Marc [Infrared Processing and Analysis Center, Caltech, Pasadena, CA 91125 (United States); Kewley, Lisa, E-mail: anahita.alavi@email.ucr.edu [Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia)

    2014-01-10

    We have obtained deep ultraviolet imaging of the lensing cluster A1689 with the WFC3/UVIS camera onboard the Hubble Space Telescope in the F275W (30 orbits) and F336W (4 orbits) filters. These images are used to identify z ? 2 star-forming galaxies via their Lyman break, in the same manner that galaxies are typically selected at z ? 3. Because of the unprecedented depth of the images and the large magnification provided by the lensing cluster, we detect galaxies 100 fainter than previous surveys at this redshift. After removing all multiple images, we have 58 galaxies in our sample in the range 19.5 < M {sub 1500} < 13 AB mag. Because the mass distribution of A1689 is well constrained, we are able to calculate the intrinsic sensitivity of the observations as a function of source plane position, allowing for accurate determinations of effective volume as a function of luminosity. We fit the faint-end slope of the luminosity function to be ? = 1.74 0.08, which is consistent with the values obtained for 2.5 < z < 6. Notably, there is no turnover in the luminosity function down to M {sub 1500} = 13 AB mag. We fit the UV spectral slopes with photometry from existing Hubble optical imaging. The observed trend of increasingly redder slopes with luminosity at higher redshifts is observed in our sample, but with redder slopes at all luminosities and average reddening of (E(B V)) = 0.15 mag. We assume the stars in these galaxies are metal poor (0.2 Z {sub ?}) compared to their brighter counterparts (Z {sub ?}), resulting in bluer assumed intrinsic UV slopes and larger derived values for dust extinction. The total UV luminosity density at z ? 2 is 4.31{sub ?0.60}{sup +0.68}10{sup 26} erg s{sup 1} Hz{sup 1} Mpc{sup 3}, more than 70% of which is emitted by galaxies in the luminosity range of our sample. Finally, we determine the global star formation rate density from UV-selected galaxies at z ? 2 (assuming a constant dust extinction correction of 4.2 over all luminosities and a Kroupa initial mass function) of 0.148{sub ?0.020}{sup +0.023} M {sub ?} yr{sup 1} Mpc{sup 3}, significantly higher than previous determinations because of the additional population of fainter galaxies and the larger dust correction factors.

  14. Ultra-faint ultraviolet galaxies at z ∼ 2 behind the lensing cluster A1689: The luminosity function, dust extinction, and star formation rate density

    International Nuclear Information System (INIS)

    We have obtained deep ultraviolet imaging of the lensing cluster A1689 with the WFC3/UVIS camera onboard the Hubble Space Telescope in the F275W (30 orbits) and F336W (4 orbits) filters. These images are used to identify z ∼ 2 star-forming galaxies via their Lyman break, in the same manner that galaxies are typically selected at z ≥ 3. Because of the unprecedented depth of the images and the large magnification provided by the lensing cluster, we detect galaxies 100× fainter than previous surveys at this redshift. After removing all multiple images, we have 58 galaxies in our sample in the range –19.5 < M 1500 < –13 AB mag. Because the mass distribution of A1689 is well constrained, we are able to calculate the intrinsic sensitivity of the observations as a function of source plane position, allowing for accurate determinations of effective volume as a function of luminosity. We fit the faint-end slope of the luminosity function to be α = –1.74 ± 0.08, which is consistent with the values obtained for 2.5 < z < 6. Notably, there is no turnover in the luminosity function down to M 1500 = –13 AB mag. We fit the UV spectral slopes with photometry from existing Hubble optical imaging. The observed trend of increasingly redder slopes with luminosity at higher redshifts is observed in our sample, but with redder slopes at all luminosities and average reddening of (E(B – V)) = 0.15 mag. We assume the stars in these galaxies are metal poor (0.2 Z ☉) compared to their brighter counterparts (Z ☉), resulting in bluer assumed intrinsic UV slopes and larger derived values for dust extinction. The total UV luminosity density at z ∼ 2 is 4.31−0.60+0.68×1026 erg s–1 Hz–1 Mpc–3, more than 70% of which is emitted by galaxies in the luminosity range of our sample. Finally, we determine the global star formation rate density from UV-selected galaxies at z ∼ 2 (assuming a constant dust extinction correction of 4.2 over all luminosities and a Kroupa initial mass function) of 0.148−0.020+0.023 M ☉ yr–1 Mpc–3, significantly higher than previous determinations because of the additional population of fainter galaxies and the larger dust correction factors.

  15. On the variable nature of low luminosity AGN

    Science.gov (United States)

    Hernandez-Garcia, Lorena

    2015-09-01

    X-ray variability is very common in active galactic nuclei (AGN), but it is still unknown if these variations occur similarly in different families of AGN. The main purpose of this work is to disentangle the true structure of low ionization nuclear emission line regions (LINERs) compared to Seyfert 2s by the study of their X-ray variations. We assembled the X-ray spectral properties, as well as the X-ray variability pattern(s), which were obtained from simultaneous spectral fittings and letting different parameters to vary in the model, derived from our previous analyses (Hernández-García et al. 2013, 2014, 2015). We find that Seyfert 2s need more complex models to fit their spectra than LINERs. Among the spectral parameters, major differences are observed in the soft (0.5-2 keV) and hard (2-10 keV) X-ray luminosities, and the Eddington ratios, which are higher in Seyfert 2s. Differences are observed also in the hard column densities, temperatures, and black hole masses, although less significant. Short-term X-ray variations cannot be claimed, while long-term variability is very common in both families. An exception is found for Compton-thick sources, which do not vary, most probably because the AGN is not accesible in the 0.5--10 keV energy band. The changes are mostly related with variations in the nuclear continuum, but other patterns of variability show that variations in the absorbers (more common in Seyfert 2s) and at soft energies can be present in a few cases. Variations at UV frequencies are observed only in LINER nuclei. The X-ray variations occur similarly in LINERs and Seyfert 2s, i.e., they are related to the nuclear continuum, although they might have different accretion mechanisms, being more efficient in Seyfert 2s. Absorption variations and changing-look sources are not usually observed in LINERs. However, UV nuclear variations are common among LINERs, indicating an unobstructed view of the inner disc where the UV emission might take place. We suggest that this might indicate the disappeareance of the broad line region and the torus in at least some LINERs.

  16. Variations of cyclotron line energy with luminosity in accreting X-ray pulsars

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Osamu, E-mail: nishi@nagano-nct.ac.jp [Department of Electronics and Computer Science, Nagano National College of Technology, 716 Tokuma, Nagano 381-8550 (Japan)

    2014-01-20

    I develop a new model for changes of cyclotron line energy with luminosity based on changes in polar cap dimensions and the direction of photon propagation as well as a shock height. In X0115+63 and V0332+53, the fundamental cyclotron line energy has been observed to decrease with increasing luminosity. This phenomenon has been interpreted as a change of a shock height with luminosity. However, the rates of the observed changes are quite different, in which the line energy in V0332+53 varies slowly with luminosity compared with that in X0115+63. I demonstrate that a new model successfully reproduces the changes of the fundamental cyclotron line energies with luminosity in both X0115+63 and V0332+53. On the other hand, the cyclotron line energies in Her X1, GX3012, and GX3041 were reported to increase with increasing luminosity. I discuss the positive correlation between the cyclotron line energy and luminosity based on changes in a beam pattern for Her X1, GX3012, and GX3041. In addition, I discuss how a switch of the predominant, observed emission region from pole1 to pole2 influences cyclotron line energy for GX3041 and A0535+26.

  17. Is the dependence of spectral index on luminosity real in optically selected AGN samples?

    CERN Document Server

    Tang, Sumin; Hopkins, Philip F; 10.1111/j.1365-2966.2007.11589.x

    2008-01-01

    We critically examine the dependence of spectral index on luminosity in optically selected AGN samples. An analysis of optically selected high-redshift quasars showed an anti-correlation of $\\alpha_{OX}$, the spectral index between the rest-frame 2500 A and 2 keV, with optical luminosity (Miyaji et al. 2006). We examine this relationship by means of Monte Carlo simulations and conclude that a constant spectral index independent of optical luminosity is still consistent with this high-z sample. We further find that that contributions of large dispersions and narrow range of optical luminosity are most important for the apparent, yet artificial, $\\alpha_{OX} - l_o$ correlation reported. We also examine another, but more complete low-z optical selected AGN sub-sample from Steffen et al. (2006), and our analysis shows that a constant spectral index independent of optical luminosity is also consistent with the data. By comparing X-ray and optical luminosity functions, we find that a luminosity independent spectral...

  18. Cold Dust Emission from X-ray AGN in the SCUBA-2 Cosmology Legacy Survey: Dependence on Luminosity, Obscuration & AGN Activity

    CERN Document Server

    Banerji, Manda; Willott, C J; Geach, J E; Harrison, C M; Alaghband-Zadeh, S; Alexander, D M; Bourne, N; Coppin, K E K; Dunlop, J S; Farrah, D; Jarvis, M; Michalowski, M J; Page, M; Smith, D J B; Swinbank, A M; Symeonidis, M; Van der Werf, P P

    2015-01-01

    We study the 850um emission in X-ray selected AGN in the 2 sq-deg COSMOS field using new data from the SCUBA-2 Cosmology Legacy Survey. We find 19 850um bright X-ray AGN in a high-sensitivity region covering 0.89 sq-deg with flux densities of S850=4-10 mJy. The 19 AGN span the full range in redshift and hard X-ray luminosity covered by the sample - 0.71 X-ray AGN - S850=0.71+/-0.08mJy. We explore trends in the stacked 850um flux densities with redshift, finding no evolution in the average cold dust emission over the redshift range probed. For Type 1 AGN, there is no significant correlation between the stacked 850um flux and hard X-ray luminosity. However, in Type 2 AGN the stacked submm flux is a factor of 2 higher at high luminosities. When averaging over all X-ray luminosities, no significant differences are found in the stacked submm fluxes of Type 1 and Type 2 AGN as well as AGN separated on the basis of X-ray hardness ratios and optical-to-infrared colours. However, at log10(LX) >44.4, dependences in ave...

  19. The luminosity function of the Large Magellanic Cloud globular cluster NGC 1866

    OpenAIRE

    Brocato, E.; V. Castellani; E. Di Carlo; Raimondo, G.; Walker, A. R.

    2003-01-01

    We present {\\it Hubble Space Telescope} {\\it V,I} photometry of the central region of the LMC cluster NGC 1866, reaching magnitudes as faint as V=27 mag. We find evidence that the cluster luminosity function shows a strong dependence on the distance from the cluster center, with a clear deficiency of low luminosity stars in the inner region. We discuss a {\\it global} cluster luminosity function as obtained from stars in all the investigated region, which appears in impressive agreement with t...

  20. Application of the Variability -> Luminosity Indicator to X-Ray Flashes

    OpenAIRE

    Reichart, D. E.; Lamb, D. Q.; Kippen, R. M.; Heise, J.; Zand, J.J.M. in't; Nysewander, M.

    2003-01-01

    We have applied the proposed variability -> luminosity indicator to ten "X-Ray Flashes" (XRFs) observed by the Wide-Field Cameras on BeppoSAX for which BATSE survey data exists. Our results suggest that the variability -> luminosity indicator probably works for XRFs. Assuming this to be so, we find that the luminosity and redshift distributions of XRFs are consistent with those of long-duration gamma-ray bursts (GRBs), and therefore most XRFs are probably not very high redshift GRBs. The fact...

  1. Experimental demonstration of interaction region beam waist position knob for luminosity leveling

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Yue [Brookhaven National Lab. (BNL), Upton, NY (United States); Bai, Mei [Inst. fuer Kernphysik, Juelich (Germany). Inst. for Advanced Simulation; Duan, Zhe [Inst. of High Energy Physics, Beijing (China); Luo, Yun [Brookhaven National Lab. (BNL), Upton, NY (United States); Marusic, Aljosa [Brookhaven National Lab. (BNL), Upton, NY (United States); Robert-Demolaize, Guillaume [Brookhaven National Lab. (BNL), Upton, NY (United States); Shen, Xiaozhe [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-05-03

    In this paper, we report the experimental implementation of the model-dependent control of the interaction region beam waist position (s* knob) at Relativistic Heavy Ion Collider (RHIC). The s* adjustment provides an alternative way of controlling the luminosity and is only known method to control the luminosity and reduce the pinch effect of the future eRHIC. In this paper, we will first demonstrate the effectiveness of the s* knob in luminosity controlling and its application in the future electron ion collider, eRHIC, followed by the detail experimental demonstration of such knob in RHIC.

  2. Gamma-Ray Burst Formation Rate Inferred from the Spectral Peak EnergyndashPeak Luminosity Relation

    OpenAIRE

    Yonetoku, D.; Murakami, T.; Nakamura, T; Yamazaki, Ryo; Inoue, A. K.; Ioka, K.

    2004-01-01

    We estimate a gamma-ray burst (GRB) formation rate based on the new relation between the spectral peak energy (Ep) and the peak luminosity. The new relation is derived by combining the data of Ep and the peak luminosities by BeppoSAX and BATSE, and it looks considerably tighter and more reliable than the relations suggested by the previous works. Using the new Ep-luminosity relation, we estimate redshifts of the 689 GRBs without known distances in the BATSE catalog and derive a GRB formation ...

  3. THE GALAXY OPTICAL LUMINOSITY FUNCTION FROM THE AGN AND GALAXY EVOLUTION SURVEY

    International Nuclear Information System (INIS)

    We present the galaxy optical luminosity function for the redshift range 0.05 2 in the Botes field of the NOAO Deep Wide-Field Survey. Our statistical sample is composed of 12,473 galaxies with known redshifts down to I = 20.4 (AB). Our results at low redshift are consistent with those from Sloan Digital Sky Survey; at higher redshift, we find strong evidence for evolution in the luminosity function, including differential evolution between blue and red galaxies. We find that the luminosity density evolves as (1 + z)(0.540.64) for red galaxies and (1 + z)(1.640.39) for blue galaxies.

  4. Luminosity Loss due to Beam Distortion and the Beam-Beam Instability

    CERN Document Server

    Wu, Juhao; Raubenheimer, Tor O; Seryi, Andrei; Sramek, Christopher K

    2005-01-01

    In a linear collider, sources of emittance dilution such as transverse wakefields or dispersive errors will couple the vertical phase space to the longitudinal position within the beam (the so-called ?banana effect'). When the Intersection Point (IP) disruption parameter is large, these beam distortions will be amplified by a single bunch kink instability which will lead to luminosity loss. We study this phenomena both analytically using linear theory and via numerical simulation. In particular, we examine the dependence of the luminosity loss on the wavelength of the beam distortions and the disruption parameter. This analysis may prove useful when optimizing the vertical disruption parameter for luminosity operation with given beam distortions.

  5. A Close Examination of the Measurement and Parametrization of Luminosity Functions in an Expanding Universe

    CERN Document Server

    Lake, S E; Tsai, C -W; Lam, A

    2016-01-01

    The astronomy community has at its disposal a large back catalog of public spectroscopic galaxy redshift surveys that can be used for the measurement of luminosity functions. Utilizing the back catalog with new photometric surveys to maximum efficiency requires modeling the color selection bias imposed on selection of target galaxies by flux limits at multiple wavelengths. The likelihood derived herein can address, in principle, all possible color selection biases through the use of a generalization of the luminosity function, $\\Phi(L)$, over the space of all spectra: the spectro-luminosity functional, $\\Psi[L_\

  6. Tile Calorimeter Upgrade Program for the Luminosity Increasing at the LHC

    OpenAIRE

    Cerqueira, A. S.(Universidade Federal do Rio De Janeiro COPPE/EE/IF, Rio de Janeiro, Brazil; Electrical Circuits Department, Federal University of Juiz de Fora (UFJF), Juiz de Fora, Brazil; Federal University of Sao Joao del Rei (UFSJ), Sao Joao del Rei, Brazil; Instituto de Fisica, Universidade de Sao Paulo, São Paulo, Brazil); System, for the ATLAS Tile Calorimeter

    2015-01-01

    The Tile Calorimeter (TileCal) is the central hadronic calorimeter of the ATLAS experiment at the Large Hadron Collider (LHC). The LHC is scheduled to undergo a major upgrade, in 2022, for the High Luminosity LHC (HL-LHC). The ATLAS upgrade program for high luminosity is split into three phases: Phase-0 occurred during $2013-2014$ and prepared the LHC for Run 2; Phase-I, foreseen for 2019, will prepare the LHC for Run 3, whereafter the peak luminosity reaches $2-3 \\times 10^{34}$ cm$^{2}s^{-1...

  7. The relationship between AGN accretion luminosity and host star formation in dusty AGNs

    Science.gov (United States)

    Dai, Yu Sophia; Wilkes, Belinda J.; Bergeron, Jacqueline; Teplitz, Harry I.; Kuraszkiewicz, Joanna

    2016-01-01

    We study the relationship between X-ray luminosity and the star formation rate (SFR) for a sample of dusty active galactic nuclei (AGNs) at 0.04 ratio. We study the dependence of the observed relation on luminosity, obscuration, supermassive black hole mass, Eddington ratio, and the fraction of AGN contribution to infrared luminosity. We also investigate the effect of binning choices on the observed trend. Comparing our results to those in the literature, we propose a unified physical scenario that explains the observed L_X-SFR connection once sample selection bias is accounted for.

  8. High luminosity, electron-positron colliders as strangeness, charm, and beauty factories

    International Nuclear Information System (INIS)

    This paper reports on high luminosity electron-positron colliders operating at the mass of the φ meson (1.02 GeV) that can produce copious K bar K0 pairs from a single quantum state. Temporal correlations in the decays of the K's provide a measure of the direct CP violating amplitude and also allow a high precision test of CPT invariance. A low energy collider with high luminosity can serve as a beam physics testbed to evaluate novel approaches to collider design that may be necessary for B factories to attain luminosities ≥ 1024 cm-2s-1

  9. Exploring Low Luminosity Quasar Diversity at z ~ 2.5 with the Gran Telescopio Canarias

    OpenAIRE

    J. W. Sulentic; Del Olmo, A.; Marziani, P

    2013-01-01

    We present preliminary results from a pencil-beam spectroscopic survey of low-luminosity quasars at z ~ 2.2-2.5. Our goal is to compare these sources with low redshift analogues of similar luminosity. High s/n and moderate resolution spectra were obtained for 15 sources using the faint object spectrograph Osiris on the 10m Gran Telescopio Canarias. The new data make possible an almost unprecedented comparison between sources with the same (moderate) luminosity at widely different cosmic epoch...

  10. Experimental demonstration of interaction region beam waist position knob for luminosity leveling

    International Nuclear Information System (INIS)

    In this paper, we report the experimental implementation of the model-dependent control of the interaction region beam waist position (s* knob) at Relativistic Heavy Ion Collider (RHIC). The s* adjustment provides an alternative way of controlling the luminosity and is only known method to control the luminosity and reduce the pinch effect of the future eRHIC. In this paper, we will first demonstrate the effectiveness of the s* knob in luminosity controlling and its application in the future electron ion collider, eRHIC, followed by the detail experimental demonstration of such knob in RHIC.

  11. Rest-frame UV Single-epoch Black Hole Mass Estimates of Low-luminosity AGNs at Intermediate Redshifts

    Science.gov (United States)

    Karouzos, Marios; Woo, Jong-Hak; Matsuoka, Kenta; Kochanek, Christopher S.; Onken, Christopher A.; Kollmeier, Juna A.; Park, Dawoo; Nagao, Tohru; Kim, Sang Chul

    2015-12-01

    The ability to accurately derive black hole (BH) masses at progressively higher redshifts and over a wide range of continuum luminosities has become indispensable in the era of large-area extragalactic spectroscopic surveys. In this paper, we present an extension of existing comparisons between rest-frame UV and optical virial BH mass estimators to intermediate redshifts and luminosities comparable to the local H? reverberation-mapped active galactic nuclei (AGNs). We focus on the Mg ii, C iv, and C iii] broad emission lines and compare them to both H? and H?. We use newly acquired near-infrared spectra from the Fiber-fed Multi-object Spectrograph instrument on the Subaru telescope for 89 broad-lined AGNs at redshifts between 0.3 and 3.5, complemented by data from the AGES survey. We employ two different prescriptions for measuring the emission line widths and compare the results. We confirm that Mg ii shows a tight correlation with H? and H?, with a scatter of ?0.25 dex. The C iv and C iii] estimators, while showing larger scatter, are viable virial mass estimators after accounting for a trend with the UV-to-optical luminosity ratio. We find an intrinsic scatter of ?0.37 dex between Balmer and carbon virial estimators by combining our data set with previous high redshift measurements. This updated comparison spans a total of three decades in BH mass. We calculate a virial factor for C iv/C iii] {log}{f}{{C}{{IV}}/{{C}}{{III}}]}=0.87 with an estimated systematic uncertainty of ?0.4 dex and find excellent agreement between the local reverberation mapped AGN sample and our high-z sample.

  12. The BH mass of nearby QSOs: a comparison of the bulge luminosity and virial methods

    CERN Document Server

    Labita, M; Falomo, R; Uslenghi, M; Labita, Marzia; Treves, Aldo; Falomo, Renato; Uslenghi, Michela

    2006-01-01

    We report on the analysis of the photometric and spectroscopic properties of a sample of 29 low redshift (z<0.6) QSOs for which both HST WFPC2 images and ultraviolet HST FOS spectra are available. For each object we measure the R band absolute magnitude of the host galaxy, the CIV (1550A) line width and the 1350A continuum luminosity. From these quantities we can estimate the black hole (BH) mass through the M(BH)-L(bulge) relation for inactive galaxies, and from the virial method based on the kinematics of the regions emitting the broad lines. The comparison of the masses derived from the two methods yields information on the geometry of the gas emitting regions bound to the massive BH. The cumulative distribution of the line widths is consistent with that produced by matter laying in planes with inclinations uniformly distributed between 10 and 50 deg, which corresponds to a geometrical factor f=1.3. Our results are compared with those of the literature and discussed within the unified model of AGN.

  13. Characterization of new ATLAS pixel Front-End prototype for upgraded luminosity

    Energy Technology Data Exchange (ETDEWEB)

    Junker, Hubertus; Barbero, Marlon; Karagounis, Michael; Wermes, Norbert [Physikalisches Institut, Universitaet Bonn (Germany)

    2009-07-01

    Around the year 2012, a first upgrade to the Large Hadron Collider (LHC) is scheduled which should enhance the luminosity by a factor 2-3. To cope with the increased hit rate, the Front-End of the ATLAS innermost pixel detector layer needs to be replaced. A new Front-End chip, called FE-I4, is presently under development in several laboratories around the world. FE-I4 is designed to cope with the higher hit rate and has an enhanced radiation tolerance. In the process of developing FE-I4, an intermediate test chip (FEI4-proto1) has been designed and produced in a 130 nm technology. Several independent blocks are implemented on this chip. The main block is an array of 61 by 14 pixel cells with associated configuration logic, bias circuits and DACs as needed for the new ATLAS pixel FE. To test this chip, a test setup consisting of two PCBs has been developed. The first PCB carries the FEI4-proto1 and routes the designated signals and supply voltages to the chip. The second PCB is a master FPGA board to control the FE, with a USB interface to connect to a PC and provide a user friendly interface. The hardware, software and firmware were developed in Bonn. Using this setup, the behavior and the characteristics of the new blocks were tested to feedback the designers of the FE-I4 and optimize the new chip.

  14. On the local radio luminosity function of galaxies; 2, environmental dependences among late-type galaxies

    CERN Document Server

    Gavazzi, G

    1999-01-01

    Using new extensive radio continuum surveys at 1.4 GHz (FIRST and NVSS), we derive the distribution of the radio/optical and radio/NIR luminosity (RLF) of late-type (Sa-Irr) galaxies (mp<15.7) in 5 nearby clusters of galaxies: A262, Cancer, A1367, Coma and Virgo. With the aim of discussing possible environmental dependences of the radio properties, we compare these results with those obtained for relatively isolated objects in the Coma supercluster. We find that the RLF of Cancer, A262 and Virgo are consistent with that of isolated galaxies. Conversely we confirm earlier claims that galaxies in A1367 and Coma have their radio emissivity enhanced by a factor of 5 with respect to isolated objects. We discuss this result in the framework of the dynamical pressure suffered by galaxies in motion through the intra-cluster gas (ram-pressure). We find that the radio excess is statistically larger for galaxies in fast transit motion. This is coherent with the idea that enhanced radio continuum activity is associate...

  15. Spin-orbit maps and electron spin dynamics for the luminosity upgrade project at HERA

    International Nuclear Information System (INIS)

    HERA is the high energy electron(positron)-proton collider at deutsches elektronen-synchrotron (DESY) in Hamburg. Following eight years of successful running, five of which were with a longitudinally spin polarized electron(positron) beam for the HERMES experiment, the rings have now been modified to increase the luminosity by a factor of about five and spin rotators have been installed for the H1 and ZEUS experiments. The modifications involve nonstandard configurations of overlapping magnetic fields and other aspects which have profound implications for the polarization. This thesis addresses the problem of calculating the polarization in the upgraded machine and the measures needed to maintain the polarization. A central topic is the construction of realistic spin-orbit transport maps for the regions of overlapping fields and their implementation in existing software. This is the first time that calculations with such fields have been possible. Using the upgraded software, calculations are presented for the polarization that can be expected in the upgraded machine and an analysis is made of the contributions to depolarization from the various parts of the machine. It is concluded that about 50% polarization should be possible. The key issues for tuning the machine are discussed. The last chapter deals with a separate topic, namely how to exploit a simple unitary model of spin motion to describe electron depolarization and thereby expose a misconception appearing in the literature. (orig.)

  16. Galaxy luminosity function per morphological type up to z=1.2

    CERN Document Server

    Ilbert, O; Tresse, L; Buat, V; Arnout, S; Lefvre, O; Burgarella, D; Zucca, E; Bardelli, S; Zamorani, G; Bottini, D; Garilli, B; Le Brun, V; MacCagni, D; Picat, J P; Scaramella, R; Scodeggio, M; Vettolani, G; Zanichelli, A; Adami, C; Arnaboldi, M; Bolzonella, M; Cappi, A; Charlot, S; Contini, T; Foucaud, S; Franzetti, P; Gavignaud, I; Guzzo, L; Iovino, A; McCracken, H J; Marano, B; Marinoni, C; Mathez, G; Mazure, A; Meneux, B; Merighi, R; Paltani, S; Pell, R; Pollo, A; Pozzetti, L; Radovich, M; Bondi, M; Bongiorno, A; Busarello, G; Ciliegi, P; Mellier, Y; Merluzzi, P; Ripepi, V; Rizzo, D

    2006-01-01

    We have computed the evolution of the rest-frame B-band luminosity function (LF) for bulge and disk-dominated galaxies since z=1.2. We use a sample of 605 spectroscopic redshifts with I_{AB}0.9 and bright galaxies showing a strongly decreasing LF slope \\alpha=+0.55 \\pm 0.21, and 32% of blue (B-I)_{AB}<0.9 and more compact galaxies which populate the LF faint-end. We observe that red bulge-dominated galaxies are already well in place at z~1, but the volume density of this population is increasing by a factor 2.7 between z~1 and z~0.6. It may be related to the building-up of massive elliptical galaxies in the hierarchical scenario. In addition, we observe that the blue bulge-dominated population is dimming by 0.7 magnitude between z~1 and z~0.6. Galaxies in this faint and more compact population could possibly be the progenitors of the local dwarf spheroidal galaxies.

  17. Evolution and the period-luminosity relation for red supergiants in the Magellanic Clouds

    CERN Document Server

    Fadeyev, Yuri A

    2013-01-01

    Excitation of radial pulsations in red supergiants of Magellanic Clouds is investigated using the stellar evolution calculations and the self-consistent solution of the equations of radiation hydrodynamics and turbulent convection. The stars with initial masses 6M_odot<=M_zams<=28 M_odot and the initial chemical composition X=0.7, 0.004<=Z<=0.008 are shown to be unstable against fundamental mode oscillations with periods from 17 to 1200 days as they become helium burning red supergiants. The period-luminosity relation slightly depends on the mass loss rate varying with a factor of three, whereas its dependence on the metal abundance is delta M_bol=0.89 delta log Z. In comparison with galactic red supergiants (Z=0.02) the low metal abundances in red supergiants of Magellanic Clouds are responsible for their higher effective temperatures and substantially narrower ranges of evolutionary stellar radius change during helium burning. Therefore on the period-mass diagram the red supergiants of Magellani...

  18. Characterization of new ATLAS pixel Front-End prototype for upgraded luminosity

    International Nuclear Information System (INIS)

    Around the year 2012, a first upgrade to the Large Hadron Collider (LHC) is scheduled which should enhance the luminosity by a factor 2-3. To cope with the increased hit rate, the Front-End of the ATLAS innermost pixel detector layer needs to be replaced. A new Front-End chip, called FE-I4, is presently under development in several laboratories around the world. FE-I4 is designed to cope with the higher hit rate and has an enhanced radiation tolerance. In the process of developing FE-I4, an intermediate test chip (FEI4-proto1) has been designed and produced in a 130 nm technology. Several independent blocks are implemented on this chip. The main block is an array of 61 by 14 pixel cells with associated configuration logic, bias circuits and DACs as needed for the new ATLAS pixel FE. To test this chip, a test setup consisting of two PCBs has been developed. The first PCB carries the FEI4-proto1 and routes the designated signals and supply voltages to the chip. The second PCB is a master FPGA board to control the FE, with a USB interface to connect to a PC and provide a user friendly interface. The hardware, software and firmware were developed in Bonn. Using this setup, the behavior and the characteristics of the new blocks were tested to feedback the designers of the FE-I4 and optimize the new chip

  19. Luminosity Function Constraints on the Evolution of Massive Red Galaxies Since z~0.9

    CERN Document Server

    Cool, Richard J; Fan, Xiaohui; Fukugita, Masataka; Jiang, Linhua; Maraston, Claudia; Meiksin, Avery; Schneider, Donald P; Wake, David A

    2008-01-01

    We measure the evolution of the luminous red galaxy (LRG) luminosity function in the redshift range 0.13L*) red galaxies have grown by less than 50% (at 99% confidence), since z=0.9, in stark contrast to the factor of 2-4 growth observed in the L* red galaxy population over the same epoch. We also investigate the evolution of the average LRG spectrum since z~0.9 and find the high-redshift composite to be well-described as a passively evolving example of the composite galaxy observed at low-redshift. From spectral fits to the composite spectra, we find at most 5% of the stellar mass in massive red galaxies may have formed within 1Gyr of z=0.9. While L* red galaxies are clearly assembled at z<1, 3L* galaxies appear to be largely in place and evolve little beyond the passive evolution of their stellar populations over the last half of c osmic history.

  20. Ultraviolet Fe II Emission in Fainter Quasars: Luminosity Dependences, and the Influence of Environments

    CERN Document Server

    Clowes, Roger G; Raghunathan, Srinivasan; Williger, Gerard M; Mitchell, Sophia M; Soechting, Ilona K; Graham, Matthew J; Campusano, Luis E

    2016-01-01

    We investigate the strength of ultraviolet Fe II emission in fainter quasars compared with brighter quasars for 1.0 ~ 25 Ang. there is a universal (i.e. for quasars in general) strengthening of W2400 with decreasing intrinsic luminosity, L3000. (2) In conjunction with previous work by Clowes et al., we find that there is a further, differential, strengthening of W2400 with decreasing L3000 for those quasars that are members of Large Quasar Groups (LQGs). (3) We find that increasingly strong W2400 tends to be associated with decreasing FWHM of the neighbouring Mg II {\\lambda}2798 broad emission line. (4) We suggest that the dependence of W2400 on L3000 arises from Ly{\\alpha} fluorescence. (5) We find that stronger W2400 tends to be associated with smaller virial estimates from Shen et al. of the mass of the central black hole, by a factor ~ 2 between the ultrastrong emitters and the weak. Stronger W2400 emission would correspond to smaller black holes that are still growing. The differential effect for LQG mem...

  1. Design Of A Vacuum System For A Compact, High Luminosity Cesr Upgrade

    CERN Document Server

    Ormond, K W

    2001-01-01

    A design for a vacuum system for a possible compact high luminosity upgrade to CESR is presented. The vacuum chamber consists of an elliptical cross-section beam chamber connected to a pumping chamber through a screen containing holes recessed in several channels. The beam chamber has a very compact cross-section compatible with two-in-one quadrupole magnets and inexpensive compact dipole magnets. Pumping will be provided by a combination of non-evaporable getter and ion pumps. Calculations were made of the conductance of the pumping slots, the impedance and loss factor of the chamber, and the transmission of beam-induced RF power through the pumping slots. We have also calculated the linear power density of synchrotron radiation and the pressure profile and beam-gas lifetime for this chamber and pump configuration. We consider the time between necessary NEG pump reactivations and the total capacity of the pumps. Tests of a prototype ion pump and a prototype pumping screen are also presented.

  2. Constraining the minimum luminosity of high redshift galaxies through gravitational lensing

    Energy Technology Data Exchange (ETDEWEB)

    Mashian, Natalie; Loeb, Abraham, E-mail: nmashian@physics.harvard.edu, E-mail: aloeb@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2013-12-01

    We simulate the effects of gravitational lensing on the source count of high redshift galaxies as projected to be observed by the Hubble Frontier Fields program and the James Webb Space Telescope (JWST) in the near future. Taking the mass density profile of the lensing object to be the singular isothermal sphere (SIS) or the Navarro-Frenk-White (NFW) profile, we model a lens residing at a redshift of z{sub L} = 0.5 and explore the radial dependence of the resulting magnification bias and its variability with the velocity dispersion of the lens, the photometric sensitivity of the instrument, the redshift of the background source population, and the intrinsic maximum absolute magnitude (M{sub max}) of the sources. We find that gravitational lensing enhances the number of galaxies with redshifts z?> 13 detected in the angular region ?{sub E}/2 ? ? ? 2?{sub E} (where ?{sub E} is the Einstein angle) by a factor of ? 3 and 1.5 in the HUDF (df/d?{sub 0} ? 9 nJy) and medium-deep JWST surveys (df/d?{sub 0} ? 6 nJy). Furthermore, we find that even in cases where a negative magnification bias reduces the observed number count of background sources, the lensing effect improves the sensitivity of the count to the intrinsic faint-magnitude cut-off of the Schechter luminosity function. In a field centered on a strong lensing cluster, observations of z?> 6 and z?> 13 galaxies with JWST can be used to infer this cut-off magnitude for values as faint as M{sub max} ? -14.4 and -16.1 mag (L{sub min} ? 2.5 10{sup 26} and 1.2 10{sup 27} erg s{sup ?1} Hz{sup ?1}) respectively, within the range bracketed by existing theoretical models. Gravitational lensing may therefore offer an effective way of constraining the low-luminosity cut-off of high-redshift galaxies.

  3. Cosmic Variance and Its Effect on the Luminosity Function Determination in Deep High z Surveys

    CERN Document Server

    Trenti, M

    2007-01-01

    We study cosmic variance in deep high redshift surveys and its influence on the determination of the luminosity function for high redshift galaxies. For several survey geometries relevant for HST and JWST instruments, we characterize the distribution of the galaxy number counts. This is obtained by means of analytic estimates via the two point correlation function in extended Press-Schechter theory as well as by using synthetic catalogs extracted from N-body cosmological simulations of structure formation. We adopt a simple luminosity - dark halo mass relation to investigate the environment effects on the fitting of the luminosity function. We show that in addition to variations of the normalization of the luminosity function, a steepening of its slope is also expected in underdense fields, similarly to what is observed within voids in the local universe. Therefore, to avoid introducing artificial biases, caution must be taken when attempting to correct for field underdensity, such as in the case of HST UDF i...

  4. High luminosity interaction region design for collisions inside high field detector solenoid

    International Nuclear Information System (INIS)

    An innovative interaction region has been recently conceived and realized on the Frascati DAΦNE lepton collider. The concept of tight focusing and small crossing angle adopted to achieve high luminosity in multibunch collisions has evolved towards enhanced beam focusing at the interaction point with large horizontal crossing angle, thanks to a new compensation mechanism for the beam-beam resonances. The novel configuration has been tested with a small detector without solenoidal field yielding a remarkable improvement in terms of peak as well as integrated luminosity. The high luminosity interaction region has now been modified to host a large detector with a strong solenoidal field which significantly perturbs the beam optics introducing new design challenges in terms of interaction region optics design, beam transverse coupling control and beam stay clear requirements. Interaction region design criteria as well as the first luminosity results obtained with the beams in collision are presented and discussed.

  5. The GRB variability/peak luminosity correlation on a Swift/BAT homogeneous sample

    International Nuclear Information System (INIS)

    We test the correlation between temporal variability and peak luminosity of the gamma-ray profile on a homogeneous sample of 36 Swift/BAT GRBs with firm redshift determination. This is the first time that this correlation can be tested on a homogeneous data sample. The correlation is confirmed, as long as the 6 GRBs with low luminosity (50 erg s-1 in the rest-frame 100-1000 keV energy band) are ignored. We confirm that the considerable scatter of the correlation already known is not due to the combination of data from different instruments with different energy bands, but it is intrinsic to the correlation itself. Thanks to the unprecedented sensitivity of Swift/BKT, the variability/peak luminosity correlation is tested on low-luminosity GRBs. Our results show that these GRBs are outliers

  6. A surprising consistency between the far-infrared galaxy luminosity functions of the field and Coma

    CERN Document Server

    Hickinbottom, S; James, P A; Ibar, E; Carter, D; Boselli, A; Collins, C A; Davies, J I; Dunne, L; Eales, S; Fuller, C; Mobasher, B; Peletier, R F; Phillipps, S; Smith, D J B; Smith, R J; Valentijn, E A

    2014-01-01

    We present new deep images of the Coma Cluster from the ESA Herschel Space Observatory at wavelengths of 70, 100 and 160 microns, covering an area of 1.75 x 1.0 square degrees encompassing the core and southwest infall region. Our data display an excess of sources at flux densities above 100 mJy compared to blank-field surveys, as expected. We use extensive optical spectroscopy of this region to identify cluster members and hence produce cluster luminosity functions in all three photometric bands. We compare our results to the local field galaxy luminosity function, and the luminosity functions from the Herschel Virgo Cluster Survey (HeViCS). We find consistency between the shapes of the Coma and field galaxy luminosity functions at all three wavelengths, however we do not find the same level of agreement with that of the Virgo Cluster.

  7. The Properties of Low-Luminosity AGN: Variability, Accretion Rate, Black Hole Mass and Color

    Science.gov (United States)

    Oleas, Juan; Podjed, Stephanie; Sarajedini, Vicki

    2016-01-01

    We present the results from a study of ~5000 Broad-Line selected AGN from the Sloan Digital Sky Survey DR7. Galaxy and AGN templates have been fit to the SDSS spectra to isolate the AGN component. The sources have absolute magnitudes in the range -23 variability analysis reveals that the anti-correlation between luminosity and variability amplitude continues to the faintest AGN in our sample (Gallastegui-Aizpun & Sarajedini 2014), though the underlying cause of the relation is still poorly understood. To address this, we further explore the connection between AGN luminosity and variability through measurement of the Hβ line width to determine black hole mass and accretion rate. We find that AGN with the highest variability amplitudes at a given luminosity appear to have lower accretion rates compared to low amplitude variables. We also investigate correlations with AGN color and accretion rate among these low-luminosity AGN.

  8. Semi-empirical model for optimising future heavy-ion luminosity of the LHC

    CERN Document Server

    Schaumann, M

    2014-01-01

    The wide spectrum of intensities and emittances imprinted on the LHC Pb bunches during the accumulation of bunch trains in the injector chain result in a significant spread in the single bunch luminosities and lifetimes in collision. Based on the data collected in the 2011 Pb-Pb run, an empirical model is derived to predict the single-bunch peak luminosity depending on the bunch’s position within the beam. In combination with this model, simulations of representative bunches are used to estimate the luminosity evolution for the complete ensemble of bunches. Several options are being considered to improve the injector performance and to increase the number of bunches in the LHC, leading to several potential injection scenarios, resulting in different peak and integrated luminosities. The most important options for after the long shutdown (LS) 1 and 2 are evaluated and compared.

  9. Prospects for SUSY and BSM Physics at the High Luminosity LHC

    CERN Document Server

    Richman, Jeffrey

    2016-01-01

    elucidate the origin of a signal. A brief discussion is also given for exotic particle searches, illustrating how high-luminosity data samples can provide key information on the properties of discovered particles.

  10. The power of relativistic jets is larger than the luminosity of their accretion disks

    CERN Document Server

    Ghisellini, G; Maraschi, L; Celotti, A; Sbarrato, T

    2014-01-01

    Theoretical models for the production of relativistic jets from active galactic nuclei predict that jet power arises from the spin and mass of the central black hole, as well as the magnetic field near the event horizon. The physical mechanism mechanism underlying the contribution from the magnetic field is the torque exerted on the rotating black hole by the field amplified by the accreting material. If the squared magnetic field is proportional to the accretion rate, then there will be a correlation between jet power and accretion luminosity. There is evidence for such a correlation, but inadequate knowledge of the accretion luminosity of the limited and inhomogeneous used samples prevented a firm conclusion. Here we report an analysis of archival observations of a sample of blazars (quasars whose jets point towards Earth) that overcomes previous limitations. We find a clear correlation between jet power as measured through the gamma-ray luminosity, and accretion luminosity as measured by the broad emission...

  11. Analysis of luminosity distributions and shape parameters of strong gravitational lensing elliptical galaxies

    CERN Document Server

    Biernaux, J; Sluse, D; Chantry, V

    2016-01-01

    Luminosity profiles of galaxies acting as strong gravitational lenses can be tricky to study. Indeed, strong gravitational lensing images display several lensed components, both point-like and diffuse, around the lensing galaxy. Those objects limit the study of the galaxy luminosity to its inner parts. Therefore, the usual fitting methods perform rather badly on such images. Previous studies of strong lenses luminosity profiles using software such as GALFIT or IMFITFITS and various PSF-determining methods have resulted in discrepant results. The present work aims at investigating the causes of those discrepancies, as well as at designing more robust techniques for studying the morphology of early-type lensing galaxies with the ability to subtract a lensed signal from their luminosity profiles. We design a new method to independently measure each shape parameter, namely, the position angle, ellipticity, and half-light radius of the galaxy. Our half-light radius measurement method is based on an innovative sche...

  12. High voltage monolithic active pixel sensors for the PANDA luminosity detector

    International Nuclear Information System (INIS)

    The PANDA-Experiment will be part of the new FAIR accelerator center at Darmstadt, Germany. It is a fixed target experiment using a antiproton beam with very high resolution for precision measurements. For a variety of measurements like energy-scans the precise determination of the luminosity is needed. The luminosity detector will determine the luminosity by measuring the angular distribution of elastically scattered antiprotons very close to the beam axis (3-8 mrad). To reconstruct antiproton tracks four layers of thinned silicon sensors with smart pixel readout on chip (HV-MAPS) will be used. Those sensors are currently under development by the Mu3e-collaboration. In the talk the concept of the luminosity measurement is shortly introduced before a summary of the status of HV-MAP prototypes and recent test beam results are presented.

  13. The ATLAS liquid argon calorimeter high-voltage system: commissioning, optimisation and LHC relative luminosity measurement

    International Nuclear Information System (INIS)

    The main goals of the ATLAS scientific programme are the observation or exclusion of physics beyond the Standard Model (SM), as well as the measurement of production cross-sections of SM processes. In order to do so, it is important to measure the luminosity at the interaction point with great precision. The ATLAS luminosity is extracted using several detectors with varying efficiencies and acceptances. Different methods, such as inclusive - or coincidence - event counting and calorimeter integrated current measurements, are calibrated and cross-compared to provide the most accurate luminosity determination. In order to provide more cross-checks and a better control on the systematic uncertainties, an independent measurement using the liquid argon (LAr) forward calorimeter (FCal), based on the readout current of its high-voltage system, has been developed. This document describes how the LAr calorimeter high-voltage system has been installed and commissioned, as well as its application to a relative luminosity determination. (author)

  14. Redshift and luminosity evolution of the intrinsic alignments of galaxies in Horizon-AGN

    CERN Document Server

    Chisari, Nora Elisa; Codis, Sandrine; Dubois, Yohan; Devriendt, Julien; Miller, Lance; Benabed, Karim; Slyz, Adrianne; Gavazzi, Raphael; Pichon, Christophe

    2016-01-01

    Intrinsic galaxy shape and angular momentum alignments can arise in cosmological large-scale structure due to tidal interactions or galaxy formation processes. Cosmological hydrodynamical simulations have recently come of age as a tool to study these alignments and their contamination to weak gravitational lensing. We probe the redshift and luminosity evolution of intrinsic alignments in Horizon-AGN between $z=0$ and $z=3$ for galaxies with an $r$-band absolute magnitude of $M_r\\leq-20$. Alignments transition from being radial at low redshifts and high luminosities, dominated by the contribution of ellipticals, to being tangential at high redshift and low luminosities, where discs dominate the signal. This cannot be explained by the evolution of the fraction of ellipticals and discs alone: intrinsic evolution in the amplitude of alignments is necessary. We constrain the evolution of the alignment amplitude as a function of luminosity for elliptical galaxies alone and find it to be in good agreement with curre...

  15. The ATLAS liquid argon calorimeter high-voltage system: commissioning, optimisation, and LHC relative luminosity measurement.

    CERN Document Server

    Arfaoui, Samir; Monnier, E

    2011-01-01

    The main goals of the ATLAS scientific programme are the observation or exclusion of physics beyond the Standard Model (SM), as well as the measurement of production cross-sections of SM processes. In oder to do so,it is important to measure the luminosity at the interaction point with great precision. The ATLAS luminosity is extracted using several detectors with varying efficiencies and acceptances. Different methods, such as inclusive - or coincidence - event counting and calorimeter integrated current measurements, are calibrated and cross-compared to provide the most accurate luminosity determination. In order to provide more cross-checks and a better control on the systematic uncertainties, an independent measurement using the liquid argon (LAr) forward calorimeter (FCal), based on the readout current of its high-voltage system, has been developed. This document describes how the LAr calorimeter high-voltage system has been installed and commissioned, as well as its application to a relative luminosity ...

  16. Dependence of the bright end of galaxy luminosity function on cluster dynamical state

    CERN Document Server

    Wen, Z L

    2014-01-01

    Luminosity function of cluster galaxies provides a fundamental constraint on galaxy evolution in cluster environments. By using the bright member galaxies of a large sample of rich clusters identified from Sloan Digital Sky Survey, we obtain the bright end of composite luminosity functions of cluster galaxies, and study their dependence on cluster dynamical state. After a redshift-evolution correction of absolute magnitude, the luminosity function of member galaxies can be well fitted by a Schechter function when the brightest cluster galaxies (BCGs) are excluded. The absolute magnitudes of BCGs follow a Gaussian function with a characteristic width of about 0.36 mag. We find that the luminosity function of galaxies in more relaxed clusters has a fainter characteristic absolute magnitude (M_{\\ast}), and these clusters have fewer bright non-BCG member galaxies but a brighter BCG. Our results suggest the co-evolution of galaxy population with cluster dynamical state and somewhat support the hierarchical formati...

  17. Studies on the measurement of differential luminosity using Bhabha events at the International Linear Collider

    Energy Technology Data Exchange (ETDEWEB)

    Sailer, Andre Philippe

    2009-04-15

    The International Linear Collider (ILC) is an electron-positron-collider with a variable center-of-mass energy {radical}(2) between 200 and 500 GeV. The small bunch sizes needed to reach the design luminosity of L{sub Peak}=2.10{sup 34} cm{sup -2}s{sup -1} necessary for the physics goals of the ILC, cause the particles to radiate beamstrahlung during the bunch crossings. Beamstrahlung reduces the center-of-mass energy from its nominal value to the effective center-of-mass energy {radical}(2'). The spectrum of the effective center-of-mass energy {radical}(2') is the differential luminosity dL/d{radical}(2'), which has to be known to precisely measure particle masses through threshold scans. The differential luminosity can be measured by using Bhabha events. The real differential luminosity is simulated by the GuineaPig software. The energy spectrum of the Bhabha events is measured by the detector and compared to the energy spectrum of Monte Carlo (MC) Bhabha events with a known differential luminosity given by an approximate parameterization. The parameterization is used to assign each MC event a weight. By re-weighting the events, until the energy spectra from the real and the MC Bhabha events match, the differential luminosity can be measured. The approximate parameterization of the differential luminosity is given by the Circe parameterization introduced by T. Ohl (1997), which does not include the correlation between the particle energies due to beamstrahlung. The Circe parameterization is extended to include the correlation and better describe the differential luminosity. With this new parameterization of the differential luminosity it is possible to predict the observed production cross section of a MC toy particle with a mass of 250 GeV/c{sup 2} to a precision better than 0.2%. Using the re-weighting fit with the extended parameterization also allows the measurement of the beam energy spreads of {sigma}{sub E}=0.0014 for electrons and {sigma}{sub E}= 0.0010 for positrons with a precision of a few percent. The total error from the measured differential luminosity and beam energy spreads on the mass of a toy particle measured in a production threshold scan is found to be 7 MeV/c{sup 2} for a 250 GeV/c{sup 2} particle, with an integrated luminosity of 5fb{sup -1} per scanning point. (orig.)

  18. Abort Gap Cleaning tests performed on 13 October 2011 during luminosity operation

    CERN Document Server

    Boccardi, A; Jeff, A; Roncarolo, F; Höfle, W; Valuch, D; Kain, V; Goddard, B; Meddahi, M; Uythoven, J; Gianfelice-Wendt, E

    2012-01-01

    Following the abort gap cleaning tests performed on 7 October 2011 [1] additional tests were carried out on 13 October 2011 to further investigate the effects of the cleaning on the luminosity production. The abort gap cleaning parameters (strength and duration of the beam excitation kick) were varied and the cleaning effectiveness measured together with the change in luminosity. The outcome is summarised in this note.

  19. Optical spectral index - luminosity relation for the 17 mapped Palomar-Green quasars

    OpenAIRE

    Zhang, Xueguang

    2013-01-01

    In this paper, the optical spectra index - luminosity relationship is checked for the well-known 17 individual mapped QSOs, in order to give one more clearer conclusion on the so far conflicting dependence of the spectral index on the luminosity for AGN. Different from the global relationships based on the color difference (photometry parameters) for samples of AGN, the more reliable relationship is determined for the multi-epoch observed individual mapped QSOs with no contamination from the ...

  20. Search for new phenomena at the high luminosity LHC with ATLAS

    CERN Document Server

    Glaysher, Paul; The ATLAS collaboration

    2016-01-01

    ATLAS sensitivity studies into the prospects of measuring Higgs boson properties and performing searches for new phenomena are presented in the context of the High Luminosity LHC. Simulated data provides expected limits on Higgs self-coupling, coupling to dark matter and constraints on discovering further Higgs bosons, with a total integrated luminosity of 3000~$\\rm{fb^{-1}}$ and collisions at $\\sqrt{s}=$14~TeV. Likewise, prospects of Supersymmetry and Di-jet resonance searches are highlighted.