WorldWideScience
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Quality Factor for the Hadronic Calorimeter in High Luminosity Conditions  

CERN Document Server

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. Currently, the OF measure for signal acceptance is implemented through a chi-square test. At a low luminosity scenario, such QF measure has been used as a way to describe how the acquired signal is compatible to the pulse shape pattern. However, at high-luminosity conditions, due to pile up, this QF acceptance is no longer possible when OF is employed, and the QF becomes a measure to indicate whether the reconstructed signal suffers or not from pile up. Methods are being developed in order to recover the superposed information, and the QF may be us...

Seixas, Jose; The ATLAS collaboration; Manhaes de Andrade Filho, Luciano; Sotto-Maior-Peralva, Bernardo

2014-01-01

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Quality Factor for the Hadronic Calorimeter in High Luminosity Conditions  

CERN Document Server

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...

Balabram, LE; The ATLAS collaboration; Filho, LM

2014-01-01

3

Luminosity and Redshift Dependence of the Covering Factor of AGNs viewed with WISE and SDSS  

CERN Document Server

In this work, we investigate the dependence of the covering factor (CF) of active galactic nuclei (AGNs) (i) on the mid-infrared (MIR) luminosity and (ii) on the redshift. We constructed 12- and 22-micron luminosity functions (LFs) at 0.006 < z < 0.3 using the Wide-field Infrared Survey Explorer} (WISE) data. Combining the WISE catalog with the Sloan Digital Sky Survey (SDSS) spectroscopic data, we selected 223,982 galaxies at 12 micron and 25,721 galaxies at 22 micron for spectroscopic classification. We then identified 16,355 AGNs at 12 micron and 4,683 AGNs at 22 micron by their optical emission lines and cataloged classifications in the SDSS. Following that, we estimated the CF as the fraction of type 2 AGN in all AGNs whose MIR emissions are dominated by the active nucleus (not their host galaxies) based on their MIR colors. We found that (i) the CF decreased with increasing MIR luminosity, regardless of the choice of type 2 AGN classification criteria, and (ii) the CF did not change significantly ...

Toba, Yoshiki; Matsuhara, Hideo; Malkan, Matthew A; Gandhi, Poshak; Nakagawa, Takao; Isobe, Naoki; Shirahata, Mai; Oi, Nagisa; Ohyama, Youichi; Takita, Satoshi; Yamauchi, Chisato; Yano, Kenichi

2014-01-01

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LORENTZ-FACTOR–ISOTROPIC-LUMINOSITY/ENERGY CORRELATIONS OF GAMMA-RAY BURSTS AND THEIR INTERPRETATION  

International Nuclear Information System (INIS)

The bulk Lorentz factor of the gamma-ray burst (GRB) ejecta (?0) is a key parameter to understanding GRB physics. Liang et al. have discovered a correlation between ?0 and isotropic ?-ray energy: ?0?E0.25?,iso,52. By including more GRBs with updated data and more methods to derive ?0, we confirm this correlation and obtain ?0 ? 91E0.29?,iso,52. Evaluating the mean isotropic ?-ray luminosities L?,iso of the GRBs in the same sample, we discover an even tighter correlation ?0 ? 249L0.30?,iso,52. We propose an interpretation to this later correlation. Invoking a neutrino-cooled hyperaccretion disk around a stellar mass black hole as the central engine of GRBs, we derive jet luminosity powered by neutrino annihilation and baryon loading from a neutrino-driven wind. Applying beaming correction, we finally derive ?0?L0.22?,iso, which is consistent with the data. This suggests that the central engine of long GRBs is likely a stellar mass black hole surrounded by a hyper-accreting disk.

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Lorentz-factor-Isotropic-luminosity/Energy Correlations of Gamma-Ray Bursts and Their Interpretation  

Science.gov (United States)

The bulk Lorentz factor of the gamma-ray burst (GRB) ejecta (?0) is a key parameter to understanding GRB physics. Liang et al. have discovered a correlation between ?0 and isotropic ?-ray energy: ?0vpropE 0.25 ?, iso, 52. By including more GRBs with updated data and more methods to derive ?0, we confirm this correlation and obtain ?0 ~= 91E 0.29 ?, iso, 52. Evaluating the mean isotropic ?-ray luminosities L ?, iso of the GRBs in the same sample, we discover an even tighter correlation ?0 ~= 249L 0.30 ?, iso, 52. We propose an interpretation to this later correlation. Invoking a neutrino-cooled hyperaccretion disk around a stellar mass black hole as the central engine of GRBs, we derive jet luminosity powered by neutrino annihilation and baryon loading from a neutrino-driven wind. Applying beaming correction, we finally derive ?0vpropL 0.22 ?, iso, which is consistent with the data. This suggests that the central engine of long GRBs is likely a stellar mass black hole surrounded by a hyper-accreting disk.

Lü, Jing; Zou, Yuan-Chuan; Lei, Wei-Hua; Zhang, Bing; Wu, Qingwen; Wang, Ding-Xiong; Liang, En-Wei; Lü, Hou-Jun

2012-05-01

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Lorentz Factor-Isotropic Luminosity/Energy Correlations of GRBS and Their Interpretation  

CERN Document Server

The bulk Lorentz factor of the gamma-ray burst (GRB) ejecta (Gamma_0) is a key parameter to understand the GRB physics. Liang et al. have discovered a correlation between Gamma_0 and isotropic gamma-ray energy: Gamma_0\\proptoE_{gamma,iso,52}^{0.25}. By including more GRBs with updated data and more methods to derive Gamma_0, we confirm this correlation and obtain Gamma_0~118E_{gamma,iso,52}^{0.26}. Evaluating the mean isotropic gamma-ray luminosities L_{gamma,iso} of the GRBs in the same sample, we discover an even tighter correlation Gamma_0~264 L_{gamma,iso,52}^{0.27}. We propose an interpretation to this later correlation. Invoking a neutrino-cooled hyperaccretion disk around a stellar mass black hole as the central engine of GRBs, we derive jet luminosity powered by neutrino annihilation and baryon loading from a neutrino-driven wind. Applying beaming correction, we finally derive Gamma_0\\proptoL_{gamma,iso}^{0.22}, which is well consistent with the data. This suggests that the central engine of long GRBs...

Lv, Jing; Lei, Wei-Hua; Zhang, Bing; Wu, Qing-Wen; Wang, Ding-Xiong; Liang, En-Wei; Lv, Hou-Jun

2011-01-01

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Luminosity calculation  

International Nuclear Information System (INIS)

The luminosity of the Tevatron collider was calculated. The data used for the calculation are the flying wire transverse beam profile and the SBD bunch profile. For the 900 GeV/c mini beta runs, the calculation was compared to the CDF luminosity monitor. The ratio of the calculation and C:BOLUMP is 0.95. 1 ref., 9 figs., 4 tabs

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Luminosity monitor  

International Nuclear Information System (INIS)

Luminosity monitors are needed in each experiment doing spin physics at RHIC. They concentrate on the luminosity aspects here because, for example, with a 10-3 raw asymmetry in an experiment, an error of 10-4 in the luminosity is as significant as a 10% polarization error. Because luminosity is a property of how two beams overlap, the luminosity at an interaction region must be measured at that interaction region in order to be relevant to the experiment at that interaction region. The authors will have to do the physics and the luminosity measurements by using labels on the event sums according to the polarization labels on the colliding bunches. Most likely they will not have independent polarization measurement on each bunch, but only on all the filled bunches in a ring, or perhaps all the bunches that are actually used in an experiment. Most analyses can then be handled by using the nine combinations gotten from three kinds of bunches in each ring, +, - and empty bunches. The empty bunches are needed to measure beam-gas background, (and some, like six in a row, are needed for the beam abort). Much of the difficulty comes from the fact that they must use a physics process to represent the luminosity. This process must have kinematic and geometric cuts both to reduce systematics such as beam-gas backgrounds, and to make it representative of the part of the interaction diamond from which the physics events come

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Luminosity Upgrades for ILC  

OpenAIRE

The possibility of increasing the luminosity for the ILC at Ecm < 350 GeV centre-of-mass by increasing the beam power are considered. It will be shown that an approximately constant luminosity can be achieved across the centre of mass energy range (250-500 GeV) without exceeding the installed AC power for 500 GeV operation. Overall a factor of four in luminosity over the published baseline could be achieved at 250 GeV resulting in 3*10**34 cm-2s-1. The implications for the d...

Harrison, Mike; Ross, Marc; Walker, Nicholas

2013-01-01

10

Light, Luminosity and the High Luminosity LHC  

CERN Multimedia

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.

2015-01-01

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Light, Luminosity and the High Luminosity LHC  

CERN Multimedia

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.

CERN Video Productions

2015-01-16

12

OLYMPUS luminosity monitoring  

International Nuclear Information System (INIS)

The OLYMPUS experiment at DESY has been measuring the ratio of positron-proton and electron-proton elastic scattering cross sections to quantify the effect of two-photon exchange, which is widely considered to be responsible for the discrepancy between measurements of the proton electric to magnetic form factor ratio with the Rosenbluth and polarization transfer methods. In order to control the systematic uncertainties to the percent level, the luminosities are monitored redundantly with high precision by measuring the rates for symmetric Moller and Bhabha scattering, and by measuring the ep-elastic count rates at forward angles and low momentum transfer with tracking telescopes based on GEM (Gas Electron Multiplier) and MWPC (Multi Wire Proportional Chamber) technology. During two data taking periods, performances of GEM and MWPC luminosity monitors are presented.

13

OLYMPUS luminosity monitoring  

International Nuclear Information System (INIS)

The OLYMPUS experiment at DESY will measure the ratio of positron-proton and electron-proton elastic scattering cross sections to quantify the effect of two-photon exchange, which is widely considered to be responsible for the discrepancy between measurements of the proton electric to magnetic form factor ratio with the Rosenbluth and polarization transfer methods. In order to control the systematic uncertainties to the percent level, the luminosities are monitored redundantly with high precision by measuring the rates for symmetric Moller and Bhabha scattering, and by measuring the ep-elastic count rates at forward angles and low momentum transfer with tracking telescopes based on GEM (Gas Electron Multiplier) and MWPC (Multi Wire Proportional Chamber) technology. The production, installation, and commissioning of the OLYMPUS GEM luminosity monitors are presented.

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ISR Superconducting High luminosity Insertion  

CERN Multimedia

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.

1981-01-01

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Luminosity monitor at PEP  

International Nuclear Information System (INIS)

The luminosity monitor system utilized by the MKII Detector and by the PEP operators is described. This system processes information from 56 photomultipliers and calculates independent luminosities for each of the 3 colliding bunches in PEP. Design considerations, measurement techniques, and sources of error in the luminosity measurement are discussed

16

Run II luminosity progress  

Energy Technology Data Exchange (ETDEWEB)

The Fermilab Tevatron Collider Run II program continues at the energy and luminosity frontier of high energy particle physics. To the collider experiments CDF and D0, over 3 fb{sup -1} of integrated luminosity has been delivered to each. Upgrades and improvements in the Antiproton Source of the production and collection of antiprotons have led to increased number of particles stored in the Recycler. Electron cooling and associated improvements have help make a brighter antiproton beam at collisions. Tevatron improvements to handle the increased number of particles and the beam lifetimes have resulted in an increase in luminosity.

Gollwitzer, K.; /Fermilab

2007-06-01

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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)

18

Satellite Luminosities in Galaxy Groups  

CERN Document Server

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 twenty. In contrast, the luminosity of the central object is predicted to increase approximately linearly with halo mass at low to intermediate masses, and logarithmically at high masses. We show that this almost non-existent mass-dependence of the satellites is in excellent agreement with the satellite population in group catalogs constructed by two different collaborations. This is remarkable because the halo model prediction was made without ever identifying groups and clusters. The halo model also predicts that the number of ...

Skibba, Ramin A; Martino, Matthew C

2007-01-01

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properties and luminosity functions  

Directory of Open Access Journals (Sweden)

Full Text Available In this article, we present an investigation of a sample of 1072 stars extracted from the Villanova Catalog of Spectroscopically Identified White Dwarfs (2005 on-line version, studying their distribution in the Galaxy, their physical properties and their luminosity functions. The distances and physical properties of the white dwarfs are determined through interpolation of their (B-V or (b-y colors in model grids. The solar position relative to the Galactic plane, luminosity function, as well as separate functions for each white dwarf spectral type are derived and discussed. We show that the binary fraction does not vary significantly as a function of distance from the Galactic disk out to 100 pc. We propose that the formation rates of DA and non-DAs have changed over time and/or that DAs evolve into non-DA types. The luminosity functions for DAs and DBs have peaks possibly related to a star burst event.

Hektor Monteiro

2007-01-01

20

Luminosity measurement at CMS  

CERN Document Server

The measurement of the luminosity delivered by the LHC is pivotal for several key physics analyses. During the first three years of running, tremendous steps forwards have been made in the comprehension of the subtleties related to luminosity monitoring and calibration, which led to an unprecedented accuracy at a hadron collider. The detectors and corresponding algorithms employed to estimate online and offline the luminosity in CMS are described. Details are given concerning the procedure based on the Van der Meer scan technique that allowed a very precise calibration of the luminometers from the determination of the LHC beams parameters. What is being prepared in terms of detector and online software upgrades for the next LHC run is also summarized.

Leonard, Jessica Lynn

2014-01-01

21

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

22

CLIC Luminosity Monitoring  

CERN Document Server

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 14 MW to the main beam dump. Luminosity monitoring for CLIC is based on high energy muons produced by beamstrahlung photons in the main dump. Threshold Cherenkov counters are proposed for the detection of these muons. The expected rates and layout for these detectors is presented. Another method for luminosity monitoring is to directly detect the beamstrahlung photons in the post-collision line. Full Monte Carlo simulation has been performed to address its feasibility.

Apyan, Armen; Gschwendtner, Edda; Lefevre, Thibault; Tygier, Sam; Appleby, Robert B

2012-01-01

23

Design and Principles of Synchrotrons and Circular Colliders: Concept of Luminosity  

CERN Document Server

This document is part of Subvolume C 'Accelerators and Colliders' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the the Section '6.4 Concept of Luminosity' of the Chapter '6 Design and Principles of Synchrotrons and Circular Colliders' with the content: 6.4 Concept of Luminosity 6.4.1 Introduction 6.4.2 Computation of Luminosity 6.4.3 Luminosity With Correction Factors 6.4.4 Integrated Luminosity 6.4.5 Measurement and Calibration of Luminosity 6.4.6 Absolute Luminosity - Lepton Colliders 6.4.7 Absolute Luminosity - Hadron Colliders

Herr, W; Muratori, B

2013-01-01

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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-, ?+?-) and photon-photon colliders. Technical problems in obtaining increased energy in each type of machine are presented. The machines relative size are also discussed

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Hydrogen-Ion Potential of Antibiotics According to the Environment Factors Temperature and Luminosity Potencial hidrogenionico de antimicrobianos, según los factores ambientales de temperatura y luminosidad Potencial hidrogeniônico de antimicrobianos, segundo os fatores ambientais temperatura e luminosidade  

Directory of Open Access Journals (Sweden)

Full Text Available The objective of this experimental study was to measure the pH of antibiotics administered by intravenous infusion - ceftriaxone sodium, vancomycin hydrochloride, metrodinazole, penicillin G potassium and amikacin sulfate - after reconstitution with sterile water and dilution with NaCl 0.9% or dextrose 5% in water, according to temperature and luminosity of the environment. The results showed that variation in the drugs' pH was less than 1.0 value and that some antibiotics remained acidic after dilution and maintained this chemical profile in all situations studied, suggesting that the studied environmental factors did not change the solutions' acid base characteristic. Some pH values measured characterize risk for the development of chemical phlebitis and infiltration, and it is important for clinical practice to emphasize the profile of intravenous solutions of antibiotics, considering method of dilution, and time to infusion.El objetivo de este estudio experimental fue medir el pH de los antibióticos de administración intravenosa ceftriaxona sódica, clorhidrato de vancomicina, metronidazol, penicilina G potásica y sulfato de amikacina, después de reconstitución con agua destilada y dilución con NaCl a 0,9%, o suero glucosado a 5%, considerando la influencia de la temperatura y luminosidad ambientales, así como el tiempo de exposición, en el comportamiento químico de esos fármacos. Los resultados demostraron variaciones que no ultrapasaron 1,0 (valor de pH y que algunos antimicrobianos, eminentemente ácidos después de la dilución, mantuvieron ese comportamiento en todas las situaciones estudiadas, no sugiriendo la influencia de factores ambientales en el comportamiento químico de las soluciones. Considerando que algunos valores de pH encontrados pueden contribuir para el desarrollo de flebitis química e infiltración, es importante enfatizar que para la práctica clínica en salud, existe la necesidad de conocer las características de las soluciones de infusión intravenosa, considerando el tipo de dilución y el tiempo de infusión.O objetivo deste estudo experimental foi medir o pH dos antibióticos de administração intravenosa ceftriaxona sódica, cloridrato de vancomicina, metronidazol, penicilina G potássica e sulfato de amicacina, após reconstituição com água destilada e diluição com NaCl 0,9%, ou soro glicosado 5%, considerando a influência da temperatura e luminosidade ambientais, assim como do tempo de exposição, no comportamento químico desses fármacos. Os resultados demonstraram variações que não ultrapassaram 1,0 valor de pH e que alguns antimicrobianos, eminentemente ácidos após a diluição, mantiveram esse comportamento em todas as situações estudadas, não sugerindo a influência de fatores ambientais no comportamento químico das soluções. Como alguns valores de pH encontrados podem contribuir para o desenvolvimento de flebite química e infiltração, é importante enfatizar para a prática clínica em saúde, a necessidade de conhecer as características das soluções de infusão intravenosa, considerando tipo de diluição e tempo de infusão.

Renata Maria Coelho Crepaldi

2010-04-01

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Hydrogen-Ion Potential of Antibiotics According to the Environment Factors Temperature and Luminosity / Potencial hidrogenionico de antimicrobianos, según los factores ambientales de temperatura y luminosidad / Potencial hidrogeniônico de antimicrobianos, segundo os fatores ambientais temperatura e luminosidade  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese O objetivo deste estudo experimental foi medir o pH dos antibióticos de administração intravenosa ceftriaxona sódica, cloridrato de vancomicina, metronidazol, penicilina G potássica e sulfato de amicacina, após reconstituição com água destilada e diluição com NaCl 0,9%, ou soro glicosado 5%, conside [...] rando a influência da temperatura e luminosidade ambientais, assim como do tempo de exposição, no comportamento químico desses fármacos. Os resultados demonstraram variações que não ultrapassaram 1,0 valor de pH e que alguns antimicrobianos, eminentemente ácidos após a diluição, mantiveram esse comportamento em todas as situações estudadas, não sugerindo a influência de fatores ambientais no comportamento químico das soluções. Como alguns valores de pH encontrados podem contribuir para o desenvolvimento de flebite química e infiltração, é importante enfatizar para a prática clínica em saúde, a necessidade de conhecer as características das soluções de infusão intravenosa, considerando tipo de diluição e tempo de infusão. Abstract in spanish El objetivo de este estudio experimental fue medir el pH de los antibióticos de administración intravenosa ceftriaxona sódica, clorhidrato de vancomicina, metronidazol, penicilina G potásica y sulfato de amikacina, después de reconstitución con agua destilada y dilución con NaCl a 0,9%, o suero gluc [...] osado a 5%, considerando la influencia de la temperatura y luminosidad ambientales, así como el tiempo de exposición, en el comportamiento químico de esos fármacos. Los resultados demostraron variaciones que no ultrapasaron 1,0 (valor de pH) y que algunos antimicrobianos, eminentemente ácidos después de la dilución, mantuvieron ese comportamiento en todas las situaciones estudiadas, no sugiriendo la influencia de factores ambientales en el comportamiento químico de las soluciones. Considerando que algunos valores de pH encontrados pueden contribuir para el desarrollo de flebitis química e infiltración, es importante enfatizar que para la práctica clínica en salud, existe la necesidad de conocer las características de las soluciones de infusión intravenosa, considerando el tipo de dilución y el tiempo de infusión. Abstract in english The objective of this experimental study was to measure the pH of antibiotics administered by intravenous infusion - ceftriaxone sodium, vancomycin hydrochloride, metrodinazole, penicillin G potassium and amikacin sulfate - after reconstitution with sterile water and dilution with NaCl 0.9% or dextr [...] ose 5% in water, according to temperature and luminosity of the environment. The results showed that variation in the drugs' pH was less than 1.0 value and that some antibiotics remained acidic after dilution and maintained this chemical profile in all situations studied, suggesting that the studied environmental factors did not change the solutions' acid base characteristic. Some pH values measured characterize risk for the development of chemical phlebitis and infiltration, and it is important for clinical practice to emphasize the profile of intravenous solutions of antibiotics, considering method of dilution, and time to infusion.

Renata Maria Coelho, Crepaldi; Cíntia, Monteiro; Maria Angélica Sorgini, Peterlini; Mavilde da Luz Gonçalves, Pedreira.

2010-04-01

27

Achieving high luminosity in the Fermilab Tevatron  

International Nuclear Information System (INIS)

Fermilab has embarked upon a program, christened Fermilab III, to raise the luminosity in the Tevatron proton-antiproton collider over the next five years by at least a factor of thirty beyond the currently achieved level of 1.6x1030cm-2sec-1. Components of the program include implementation of electrostatic separators, Antiproton Source improvements, installation of cold compressors, doubling the existing linac output energy, and the construction of a new accelerator--the Fermilab Main Injector. Basic limitations in the achievement of higher luminosity in the Tevatron, the strategy developed to achieve the Fermilab III goals, and the evolution of luminosity throughout the period will be discussed. 1 fig., 2 tabs

28

Evolution of the luminosity function  

Science.gov (United States)

In this review, the currently published, complete, spectroscopically identified samples of quasars are assembled to produce a composite luminosity function, independent of evolutionary assumptions. Two interpretations of the change with cosmic time provide reasonable fits to the data. Luminosity evolution implies a fixed population of host objects, with nuclear luminosity that fades with advancing cosmic time; some dependence of the timescale on intrinsic luminosity is required. Density evolution traces objects of comparable luminosity to find the change in space density, without a requirement of long lifetime. The change in co-moving volume density depends on luminosity; newer data suggest that somewhat stronger evolution is required at the low luminosity end than the models of Schmidt and Green allowed. Caution is advised in drawing direct physical conclusions about the evolution of individual quasars from mathematical representations of ensemble properties.

Green, Richard F.

29

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

30

Supernova type I luminosity  

International Nuclear Information System (INIS)

The full time-dependent radiation spectrum of a supernova starts when the explosion shock wave reaches the surface of the presupernova envelope. An early radiation spectrum emitted by the expanded and cooling shock-ejected outer layers of an initially compact (R = 108 cm) type I supernova is derived. The relativistically ejected matter is presumably cosmic rays. The Doppler shifted and relativistically time contracted Planck radiation emitted from the expanding surface layers results in an emitted radiation associated with the cooling corresponding to an energy flux of 1.3 x 1043 t-1.05 ergs sec-1 with a spectrum I(h?) dh? = 1.5 x 1043 (h?)-0.92 ergs eV-1 and time behavior (h?)/sub eff/ = 108 t-0.61 eV. The optical luminosity from the shock is thus low congruent to 1040 ergs sec-1 and 1043 ergs total so that it would not be seen as a precursor to the main optical outburst occurring several days later. The x-ray luminosity (several x 1043 ergs in milliseconds) is observable but small compared to extended envelope models. The later optical light curve is then interpreted in terms of radioactive heating, ionization and excitation by 0.2 M/sub solar/ of 56Ni decaying via 56Co to 56Fe. Van Hise (1974) has already pointed out that the two optical decay constants are closely given by the respective radioactive decay constants multiplied by 3/4. This is interpreted as requiring efficiency to produce optical radiation, the Fe+blend, proportional to the (decay rate)/sup 1/3/. It is further noted that when the two optical decay rates are extrapolated to zero time, the intercepts agree with the predicted ratio of deposited energy from 56Ni ? 56Co, and from 56Co ? 56Fe when the appropriate fractional absorption of gamma rays and beta particles is included. The width and magnitude of the peak luminosity has already been calculated by Colgate and McKee

31

Luminosity determination at COMPASS  

Energy Technology Data Exchange (ETDEWEB)

In 2009, a Deep Virtual Compton Scattering test run with a 160 GeV muon beam impinging on a liquid hydrogen target was performed at the COMPASS experiment at CERN. The data were acquired using a system of inclusive muon triggers, consisting of scintillator hodoscopes. As a first step of the analysis the inclusive cross section will be extracted. To achieve this aim, the luminosity is needed which is proportional to the beam flux in a fixed-target experiment. The flux is determined by two methodes: counting tracks using a random trigger or using the Scaler information of the scintillating fibre station in the beam telescope of the experiment. By calculating the cross section for Deep Inelastic Scattering and the structure function F{sub 2}{sup p}, the results are cross checked with results from NMC which cover a similar kinematic range.

Du Fresne von Hohenesche, Nicolas [Mainz Univ. (Germany). Inst. fuer Kernphysik; European Organization for Nuclear Research (CERN), Geneva (Switzerland)

2012-07-01

32

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)

33

Luminosity function of GRBs  

CERN Document Server

The luminosity function (LF) statistics applied to the BATSE GRBs (sources of GUSBAD catalog) is the theme approached in this work. The LF is a strong statistical tool to extract useful information from astrophysical samples, where 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. One of the main differences between the Fireshell and Fireball models is the explanation of the GRB prompt emission, where the first claims that it is divided in two physical processes: 1) transparency of a optically thick Freshell producing the P-GRB emission and 2) interaction of a relativistic shell (composed by baryons electron-positron-photon) against the CBM (circumburst medium), producing the emission so-called extended afterglow peak (EAP). However, the Fireball model, the most quoted one, claims that the prompt emission is caused by interactions among several rela...

Lemos, L J Rangel; Ruffini, R; Malheiro, M

2013-01-01

34

Luminosity tuning at KEKB-2  

International Nuclear Information System (INIS)

We routinely make tuning on machine parameters related to beam collision at KEKB even during the physics experiment. The purpose of this adjustment called 'knob tuning' is to maintain the high luminosity by optimizing the collision parameters and to obtain an even higher luminosity. We installed crab cavities in February 2007. The method of luminosity tuning changed to some extent and some new tuning method were introduced. In this report, we describe the developments after the 2nd annual meeting of particle accelerator society of Japan 2005. (author)

35

Luminosity monitor studies for TESLA  

Energy Technology Data Exchange (ETDEWEB)

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{sup +}e{sup -} 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) 8 refs.

Napoly, O. [CEA Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l`Instrumentation Associee; Schulte, D. [European Organization for Nuclear Research CERN, Geneva (Switzerland)

1997-11-01

36

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%

37

Luminosity function of Seyfert galaxies  

International Nuclear Information System (INIS)

The sample of 121 Seyfert galaxies in an area covering 15 000 square degrees is formed. The space density (6.3x10-5 Mpc-3) and the luminosity distribution of these galaxies are determined. Mean (in the range -18.5 >= Msub(p) >= -23.5) absolute magnitude of Seyfert galaxies (Msub(p))=-19.74+-0.08. A parameter n in the relation between space density and photographic luminosity phi approximately Lsub(p)sup(-n) is found to be equal to 1.6 at the low-luminosity end (Msub(p)>-21.0) and 3.5 - at the bright one. To the class of Seyfert galaxies belongs 1/250 of all galaxies in the range -19 >=Msub(p) >= -23. Sy2 galaxies comprise no less than a quarter of Seyfert galaxies and their distribution of absolute magnitudes is slightly shifted to the low-luminosity end

38

Precision luminosity measurements at LHCb  

Science.gov (United States)

Measuring cross-sections at the LHC requires the luminosity to be determined accurately at each centre-of-mass energy ?s. In this paper results are reported from the luminosity calibrations carried out at the LHC interaction point 8 with the LHCb detector for ?s = 2.76, 7 and 8 TeV (proton-proton collisions) and for ?sNN = 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 ?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 determines the luminosity with a precision of 1.16%. This represents the most precise luminosity measurement achieved so far at a bunched-beam hadron collider.

The LHCb collaboration

2014-12-01

39

Emittance preservation and luminosity tuning in future linear colliders  

OpenAIRE

The future International Linear Collider (ILC) and Compact Linear Collider (CLIC) are intended for precision measurements of phenomena discovered at the Large Hadron Collider (LHC) and also for the discovery of new physics. In order to offer optimal conditions for such experiments, the new colliders must produce very-high-luminosity collisions at energies in the TeV regime. Emittance growth caused by imperfections in the main linacs is one of the factors limiting the luminosity of CLIC and IL...

Eliasson, Peder

2008-01-01

40

Sub-L* Galaxies at Redshifts z~4, 3, and 2: Their UV Luminosity Function and Luminosity Density  

OpenAIRE

We use very deep (R_lim=27) UGRI imaging to study the evolution of the faint end of the UV-selected galaxy luminosity function from z~4 to z~2. We find that the luminosity function evolves with time and that this evolution is differential with luminosity: the number of sub-L* galaxies increases from z~4 to z~3 by at least a factor of 2.3, while the bright end of the LF remains unchanged. Potential systematic biases restrict our ability to draw strong conclusions at lower red...

Sawicki, Marcin; Thompson, David

2005-01-01

41

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)

42

EVOLUTION OF THE H? LUMINOSITY FUNCTION  

International Nuclear Information System (INIS)

The Smithsonian Hectospec Lensing Survey (SHELS) is a window on the star formation history over the last 4 Gyr. SHELS is a spectroscopically complete survey for Rtot 0. We use the 10k spectra to select a sample of pure star-forming galaxies based on their H? emission line. We use the spectroscopy to determine extinction corrections for individual galaxies and to remove active galaxies in order to reduce systematic uncertainties. We use the large volume of SHELS with the depth of a narrowband survey for H? galaxies at z ? 0.24 to make a combined determination of the H? luminosity function at z ? 0.24. The large area covered by SHELS yields a survey volume big enough to determine the bright end of the H? luminosity function from redshift 0.100 to 0.377 for an assumed fixed faint-end slope ? = -1.20. The bright end evolves: the characteristic luminosity L* increases by 0.84 dex over this redshift range. Similarly, the star formation density increases by 0.11 dex. The fraction of galaxies with a close neighbor increases by a factor of 2-5 for LH? ?> L* in each of the redshift bins. We conclude that triggered star formation is an important influence for star-forming galaxies with H? emission.

43

Technology of high luminosity detectors  

International Nuclear Information System (INIS)

The Workshop on Collider Detectors: Present Capabilities and Future Possibilities focused on the problems posed by high luminosity and high energy at hadron colliders. Four working groups considered problems in individual detector elements, tracking chambers, calorimeters, triggers and particle identification devices. A fifth group reviewed the general problems of detector systems. The working groups concluded that there are technical solutions for the problems of a luminosity of 1033 cm-2 sec-1. Everything is difficult and continued R and D is necessary to improve detectors

44

Precision luminosity measurements at LHCb  

CERN Document Server

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...

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

45

The SDSS DR6 Luminosity Functions of Galaxies  

OpenAIRE

We present number counts, luminosity functions (LFs) and luminosity densities of galaxies obtained using the Sloan Digital Sky Survey Sixth Data Release in all SDSS photometric bands. Thanks to the SDSS DR6, galaxy statistics have increased by a factor of ~9 in the u-band and by a factor of ~4-5 in the rest of the SDSS bands with respect to the previous work of Blanton et al. (2003b). In addition, we have achieved a high redshift completeness in our galaxy samples. Firstly, ...

Montero-dorta, Antonio D.; Prada, Francisco

2008-01-01

46

The Planetary Nebula Luminosity Function  

OpenAIRE

The [O III] 5007 planetary nebula luminosity function (PNLF) occupies an important place on the extragalactic distance ladder: it is the only standard candle that can be applied to all the large galaxies of the Local Supercluster. We review the method's precision, and use it to show that the distance scale defined by Cepheids and the Surface Brightness Fluctuation method is likely too large by ~ 7%. We also discuss some of the physics underlying the phenomenon, and present c...

Ciardullo, Robin

2004-01-01

47

Periods, amplitudes, and luminosities of red supergiants  

Energy Technology Data Exchange (ETDEWEB)

The periods of 22 red supergiants have been determined using the results of electrophotometric observations. The period-luminosity-spectrum and amplitude-luminosity-spectrum dependences for the red supergiants have been obtained. The masses and luminosities of these stars are estimated.

Abramian, G.V.

1984-09-01

48

Periods, amplitudes, and luminosities of red supergiants  

International Nuclear Information System (INIS)

The periods of 22 red supergiants have been determined using the results of electrophotometric observations. The period-luminosity-spectrum and amplitude-luminosity-spectrum dependences for the red supergiants have been obtained. The masses and luminosities of these stars are estimated

49

The first high-luminosity insertion in the ISR  

CERN Document Server

One of the means proposed to increase the luminosity in storage rings, a so-called low- beta insertion, has been put successfully into operation in the Intersecting Storage Rings (ISR). By installing five quadrupoles in each ring around one intersection, a reduction of beam height by a factor 2.3 has been measured, and, with proper matching, the perturbation to the rest of the machine was found to be negligible. With circulating beams of 20 A and 24 A a luminosity of 2.11*10/sup 31/ cm/sup -2/ s/sup -1/ has been achieved. This paper reports the results of tests conducted. (8 refs).

Gourber, J P; Pichler, S

1975-01-01

50

Prospects for the ATLAS upgrade for the high luminosity LHC  

CERN Document Server

The Large Hadron Collider (LHC) will continue to be the main infrastructure for experimental High Energy Physics. To maintain the physics potential of LHC, a series of upgrade will be required to increase the yearly integrated luminosity by a factor 10 compared to the original design value. ATLAS will need to correspondingly upgrade its detectors, triggers and data acquisition systems. The aim is to be able to maintain a high efficiency for Standard Model and Beyond Standard Model signals despite a much difficult environment caused by the increasing number of pileup from the high luminosity. This presentation will cover the prospects for the ATLAS upgrade for the high luminosity LHC and present the various planned detector upgrades and their effect on the performance.

Brenner, R; The ATLAS collaboration

2013-01-01

51

Luminosities of recycled radio pulsars in globular clusters  

CERN Document Server

Using Monte Carlo simulations, we model the luminosity distribution of recycled pulsars in globular clusters as the brighter, observable part of an intrinsic distribution and find that the observed luminosities can be reproduced using either log-normal or power-law distributions as the underlying luminosity function. For both distributions, a wide range of model parameters provide an acceptable match to the observed sample, with the log-normal function providing statistically better agreement in general than the power-law models. Moreover, the power-law models predict a parent population size that is a factor of between two and ten times higher than for the log-normal models. We note that the log-normal luminosity distribution found for the normal pulsar population by Faucher-Gigu\\`ere and Kaspi is consistent with the observed luminosities of globular cluster pulsars. For Terzan~5, our simulations show that the sample of detectable radio pulsars, and the diffuse radio flux measurement, can be explained using ...

Bagchi, Manjari; Chennamangalam, Jayanth

2011-01-01

52

The Intrinsic Quasar Luminosity Function: Accounting for Accretion Disk Anisotropy  

Science.gov (United States)

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.

DiPompeo, M. A.; Myers, A. D.; Brotherton, M. S.; Runnoe, J. C.; Green, R. F.

2014-05-01

53

Deriving the Quasar Luminosity Function from Accretion Disk Instabilities  

CERN Document Server

We have derived the quasar luminosity function assuming that the quasar activity is driven by a thermal-viscous unstable accretion disk around a supermassive black hole. The instabilities produce large amplitude, long-term variability of a single source. We take a light curve of a single source and calculate the luminosity function, from the function of time it spends at each luminosity. Convolving this with an assumed mass distribution we fit well the observed optical luminosity function of quasars at four redshifts. As a result we obtain the evolution of the mass distribution between redshifts 2.5 and 0.5. The maximum of the active black hole mass function moves towards lower mass by a factor ~10 at the low redshift. The number of high mass sources declines rapidly, and so low mass sources become dominant at lower redshift. The main conclusions are following: 1) The quasar long-term variability due to the disk thermal-viscous instabilities provides a natural explanation for the observed quasar luminosity fu...

Siemiginowska, A L; Siemiginowska, Aneta; Elvis, Martin

1997-01-01

54

Reduced Wolf-Rayet Line Luminosities at Low Metallicity  

CERN Document Server

New NTT/EMMI spectrophotometry of single WN2-5 stars in the Magellanic Clouds are presented, from which HeII 4686 line luminosities have been derived, and compared with observations of other Magellanic Cloud WR stars. SMC WN3-4 stars possess line luminosities which are a factor of 4 times lower than LMC counterparts, incorporating several binary SMC WN3-4 stars. Similar results are found for WN5-6 stars, despite reduced statistics, incorporating observations of single LMC WN5-9 stars. CIV 5808 line luminosities of carbon sequence WR stars in the SMC and IC1613 (both WO subtypes) are a factor of 3 lower than LMC WC stars from Mt Stromlo/DBS spectrophotometry, although similar results are also obtained for the sole LMC WO star. We demonstrate how reduced line luminosities at low metallicity follow naturally if WR winds are Z-dependent, as recent results suggest. We apply mass loss-Z scalings to atmospheric non-LTE models of Milky Way and LMC WR stars to predict the wind signatures of WR stars in the metal-poor ...

Crowther, P A; Crowther, Paul A

2006-01-01

55

Luminosity Measurements with the ATLAS Detector  

CERN Document Server

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...

Maettig, Stefan; Pauly, T

56

Luminosity spectrum reconstruction at linear colliders  

International Nuclear Information System (INIS)

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. 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. (orig.)

57

The D0 Run IIb Luminosity Measurement  

OpenAIRE

An assessment of the recorded integrated luminosity is presented for data collected with the D0 detector at the Fermilab Tevatron Collider from June 2006 to September 2011 (Run IIb). In addition, a measurement of the effective cross section for inelastic interactions, also referred to as the luminosity constant, is reported. This measurement incorporates new features that lead to a substantial improvement in the precision of the result. A luminosity constant of \\sigma_{LM} =...

Casey, B. C. K.; Corcoran, M.; Devaughan, K.; Enari, Y.; Gallas, E.; Katsanos, I.; Linnemann, J.; Orduna, J.; Partridge, R.; Prewitt, M.; Schellman, H.; Snow, G. R.; Verzocchi, M.

2012-01-01

58

The AGN Contribution to Galaxy Merger Infrared Luminosities  

Science.gov (United States)

We investigate the contribution of AGN activity to the infrared luminosity of interacting galaxies by analyzing dust radiative transfer calculations of a hydrodynamically simulated merger, created with the code GADGET-2. We focus on emission in the mid-IR to far-IR wavelength ranges, and trace the luminosity density of an interacting gas-rich galaxy pair throughout its evolution. We find that the AGN contribution to IR luminosity is greatest during and immediately after coalescence of the galaxies' central black holes. This period lasts roughly 80 Myr, during which time the increased influx of gas to the center of the merger increases the total luminosity by a factor of a thousand or more due to both increased star formation rate (SFR) and black hole accretion. We compare different interstellar medium models used to describe sub-resolution gas and dust clouds in the radiative transfer calculations by studying the color evolution of our merger in the Herschel Space Observatory photometric filter bands, and compare the results to Herschel observations. We conclude that using infrared luminosity as a simple surrogate for SFR can overestimate the true rate, due to the contribution of AGN or other dust heating mechanisms. This conclusion has an especially significant impact in assessing the star formation activity in high-redshift galaxies for which luminosity (the best measured property) may not accurately measure the SFR, and in cases where the molecular gas content can differ from that of local systems. Further work will extend this analysis to simulations of mergers between late-type galaxies. This work was supported in part by the NSF REU and DOD ASSURE programs under NSF grant no. 1262851, by the Smithsonian Institution and by NASA grant NNX14AJ6IG.

Rosenthal, Lee; Hayward, Christopher C.; Smith, Howard; Ashby, Matthew; Hung, Chao-Ling; Martinez-Galarza, Rafael; Weiner, Aaron; Zezas, Andreas; Lanz, Lauranne

2015-01-01

59

ISR Superconducting High-Luminosity (low beta ) insertion  

CERN Multimedia

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.

1981-01-01

60

z~1 Lya Emitters I. The Luminosity Function  

CERN Document Server

We construct a flux-limited sample of 135 candidate z~1 Lya emitters (LAEs) from Galaxy Evolution Explorer (GALEX) grism data using a new data cube search method. These LAEs have luminosities comparable to those at high redshifts and lie within a 7 Gyr gap present in existing LAE samples. We use archival and newly obtained optical spectra to verify the UV redshifts of these LAEs. We use the combination of the GALEX UV spectra, optical spectra, and X-ray imaging data to estimate the active galactic nucleus (AGN) fraction and its dependence on Lya luminosity. We remove the AGNs and compute the luminosity function (LF) from 60 z~1 LAE galaxies. We find that the best fit LF implies a luminosity density increase by a factor of ~1.5 from z~0.3 to z~1 and ~20 from z~1 to z~2. We find a z~1 volumetric Lya escape fraction of 0.7+/-0.4%.

Wold, Isak G B; Cowie, Lennox L

2014-01-01

61

Missing mass from low-luminosity stars  

International Nuclear Information System (INIS)

Results from a deep photometric survey for low-luminosity stars show a turnup to the luminosity function at faint magnitudes, and reopen the possibility that the missing mass in the solar neighbourhood is made up of stars after all. (author)

62

Luminosity determination in ?s = 7 TeV proton collisions using the LHCf Front Counter at LHC  

International Nuclear Information System (INIS)

In the Large Hadron Collider forward (LHCf) experiment, the luminosity is determined with the counting rates of detectors called Front Counter. During the LHCf physics operation at ?s = 7 TeV in 2010, two series of calibration run in the conversion factors from the counting rate to the luminosity were carried out on 26th of April and 9th of May. Using the luminosities determined in the April and May scans with 5 % and 4 % accuracy, the conversion factors were determined with 5.0 % accuracy, providing the luminosity determination at the LHCf experiment with this accuracy.

63

Luminosity determination in $\\sqrt{s}$ = 7 TeV proton collisions using the LHCf Front Counter at LHC  

CERN Document Server

In the Large Hadron Collider forward (LHCf) experiment, the luminosity is determined with the counting rates of detectors called Front Counter. During the LHCf physics operation at ?s = 7 TeV in 2010, two series of calibration run in the conversion factors from the counting rate to the luminosity were carried out on 26th of April and 9th of May. Using the luminosities determined in the April and May scans with 5 % and 4 % accuracy, the conversion factors were determined with 5.0 % accuracy, providing the luminosity determination at the LHCf experiment with this accuracy.

Taki, K; Bonechi, L; Bongi, M; Castellini, G; D'Alessandro, R; Fukatsu, K; Haguenauer, M; Itow, Y; Kasahara, K; Mase, T; Kawade, K; Ricciarini, S; Macina, D; Masuda, K; Menjo, H; Mitsuka, G; Muraki, Y; Noda, K; Papini, P; Perrot, A L; Sako, T; Shimizu, Y; Suzuki, K; Suzuki, T; Tamura, T; Torii, S; Tricomi, A; Turner, W C

2012-01-01

64

The QSO variability-luminosity-redshift relation  

CERN Document Server

The relationship between variability, luminosity and redshift in the South Galactic Pole QSO sample is examined in an effort to disentangle the effects of luminosity and redshift in the amplitude of the optical variations. The anticorrelation between variability and luminosity found by other authors is confirmed. Our analysis also supports claims that variability increases with redshift, most likely due to an anticorrelation between variability and wavelength. In particular, our parametric fits show that the QSO variability-wavelength relation is consistent with that observed in low-luminosity nearby active galactic nuclei. The results are used to constrain Poissonian-type models. We find that if QSO variability results from a random superposition of pulses, then the individual events must have B-band energies between $\\sim 10^{50}$ and a few times $10^{51}$ erg and time-scales of $\\sim 2$ yr. Generalized Poissonian models in which the pulse energy and lifetime scale with luminosity are also discussed.

Fernandes, R C; Terlevich, R J

1996-01-01

65

Operational Results from the LHC Luminosity Monitors  

CERN Document Server

The Luminosity Monitors for the high luminosity regions in the LHC have been operating to monitor and optimize the luminosity since the beginning of the 2009 run. The device is a gas ionization chamber, which has the ability to resolve bunch-by-bunch luminosity as well as survive the extreme levels of radiation at nominal high intensity LHC operations. The chambers are installed at the zero degree collision angle inside the neutral absorbers 140 m from the interaction point and monitor showers produced by high energy neutral particles from the collisions. A second device, a photo-multiplier based system (PMT) located directly behind the gas ionization chamber, has been also used at low luminosities. We will present operational results for the ionization chambers for both pp and Pb-Pb collisions. These measurements include signal, noise and background studies, and correlation between the gas ionization detector and the PMT. Also, comparison with ongoing modeling efforts will be included.

Miyamoto, R; Matis, H S; Ratti, A; Turner, W C; Yaver, H; Stezelberger, T

2011-01-01

66

Luminosity Monitoring in ATLAS with MPX Detectors  

Science.gov (United States)

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.

Asbah, Nedaa

2014-06-01

67

Luminosity Monitoring in ATLAS with MPX Detectors  

CERN Document Server

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 sqrt(s)=8 TeV proton-proton collisions.

Sopczak, Andre

2014-01-01

68

Luminosity Monitoring in ATLAS with MPX Detectors  

CERN Document Server

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 $\\sqrt{s}=8$ TeV proton-proton collisions.

The ATLAS collaboration

2013-01-01

69

THE z = 5 QUASAR LUMINOSITY FUNCTION FROM SDSS STRIPE 82  

Energy Technology Data Exchange (ETDEWEB)

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.

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

70

The Environmental Dependence of the Luminosity-Size Relation for Galaxies  

CERN Document Server

We have examined the luminosity-size relationship as a function of environment for 12150 SDSS galaxies with precise visual classifications from the catalog of Nair & Abraham (2010a). Our analysis is subdivided into investigations of early-type galaxies and late-type galaxies. Early-type galaxies reveal a surprisingly tight luminosity-size relation. The dispersion in luminosity about the fiducial relation is only ~0.14 dex (0.35 mag), even though the sample contains galaxies which differ by a factor of almost 100 in luminosity. The dispersion about the luminosity-size relation is comparable to the dispersion about the fundamental plane, even though the luminosity-size relation is fundamentally simpler and computed using purely photometric parameters. The key contributors to the dispersion about the luminosity-size relation are found to be color and central concentration. Expanding our analysis to the full range of morphological types, we show that the slope, zero point, and scatter about the luminosity-siz...

Nair, Preethi B; Abraham, Roberto G

2010-01-01

71

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

72

Luminosity determination at HERA-B  

CERN Document Server

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.

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

73

BDS tuning and luminosity monitoring in CLIC  

CERN Document Server

The emittance preservation in the Beam Delivery System (BDS) is one of the major challenges in CLIC. The fast detuning of the final focus optics requires an on-­line tuning procedure in order to keep luminosity close to the maximum. Different tuning techniques have been applied to the CLIC BDS and in particular to the Final Focus System (FFS) in order to mitigate static and dynamic imperfections. Some of them require a fast luminosity measurement. Here we study the possibility to use beam-­beam backgrounds processes at CLIC 3 TeV CM energy as fast luminosity signal. In particular the hadrons multiplicity in the detector region is investigated.

Dalena, Barbara; Latina, Andrea; Marin, Eduardo; Pfingstner, Jurgen; Schulte, Daniel; Snuverink, Jochem; Tomas, Rogelio; Zamudio, Guillermo

2011-01-01

74

Prospects for the high-luminosity LHC  

Energy Technology Data Exchange (ETDEWEB)

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{sup ?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.

Jezequel, S.

2013-12-15

75

Luminosity determination at HERA-B  

Energy Technology Data Exchange (ETDEWEB)

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.)

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

76

SLC-2000: A luminosity upgrade for the SLC  

International Nuclear Information System (INIS)

The authors discuss a possible upgrade to the Stanford Linear Collider (SLC), whose objective is to increase the SLC luminosity by at least a factor 7, to an average Z production rate of more than 35,000 per week. The centerpiece of the upgrade is the installation of a new superconducting final doublet with a field gradient of 240 T/m, which will be placed at a distance of only 70 cm from the interaction point. In addition, several bending magnet in each final focus will be lengthened and two octupole correctors are added. A complementary upgrade of damping rings and bunch compressors will allow optimum use of the modified final focus and can deliver, or exceed, the targeted luminosity. The proposed upgrade will place the SLC physics program in a very competitive position, and will also enable it to pursue its pioneering role as the first and only linear collider

77

Luminosity function of contact binaries based on the ASAS survey  

CERN Document Server

The luminosity function for contact binary stars of the W~UMa-type is evaluated on the basis of the ASAS photometric project covering all stars south of delta= +28 within a magnitude range 8luminosity function required a correction for missed systems with small amplitudes and with orbital periods longer than 0.562 days; the correction, by a factor of 3 times, carries an uncertainty of about 30%.

Rucinski, S M

2006-01-01

78

Simulations of luminosity monitor for PANDA experiment  

International Nuclear Information System (INIS)

The Panda experiment at the future GSI facility FAIR (Facility of Antiprotons Research) is designed to address broad physics programs in hadron physics using the antiproton beam. The physics program includes, among other things, the study of charmonium spectrum and open charm states with high precision and search of exotic hybrids and glueballs in the charmonium mass region. While in some measurements, such as, the resonance scans to determine the resonance widths and mass, only a relative measurement of luminosity may be sufficient, the measurement of the time integrated luminosity at the interaction point is essential in most of the cases to determine the cross section for physical processes. A luminosity monitor based on Si-strip detectors is planned for the PANDA experiment. In the present work, initial simulation studies that have been started at NPD, BARC on the design and optimization of the Si-strip based luminosity monitor for the PANDA experiment have been reported

79

LHC beam and luminosity lifetimes revisited  

CERN Document Server

The single beam lifetimes and luminosity lifetime during LHC Stable Beams in 2012 for a large number of fills are considered. The evolution of single beam lifetime through a given fill is obtained from fits to BCT data and from the combination of luminosity losses and calibrated beam loss to collimation. A breakdown of the single beam lifetime into principle components is performed allowing a quantitative picture of component lifetime evolution during Stable Beams. The situation before and after the octupole polarity change and concomitant increase in chromaticity in August 2012 are compared. The analysis is extended to the luminosity lifetime and an attempt to made to evaluate emittance growth from the luminous region size and luminosity evolution through the fill.

Lamont, M

2014-01-01

80

The D0 Run IIb luminosity measurement  

International Nuclear Information System (INIS)

An assessment of the recorded integrated luminosity is presented for data collected with the D0 detector at the Fermilab Tevatron Collider from June 2006 to September 2011 (Run IIb). In addition, a measurement of the effective cross-section for inelastic interactions, also referred to as the luminosity constant, is reported. This measurement incorporates new features that lead to a substantial improvement in the precision of the result. A luminosity constant of ?LM=48.3±1.9±0.6mb is obtained, where the first uncertainty is due to the accuracy of the inelastic cross-section used by both CDF and D0, and the second uncertainty is due to D0 sources. The recorded luminosity for the highest ET jet trigger is Lrec=9.2±0.4fb?1, with a relative uncertainty of 4.3%.

81

The D0 Run IIb luminosity measurement  

Energy Technology Data Exchange (ETDEWEB)

An assessment of the recorded integrated luminosity is presented for data collected with the D0 detector at the Fermilab Tevatron Collider from June 2006 to September 2011 (Run IIb). In addition, a measurement of the effective cross-section for inelastic interactions, also referred to as the luminosity constant, is reported. This measurement incorporates new features that lead to a substantial improvement in the precision of the result. A luminosity constant of ?{sub LM}=48.3±1.9±0.6mb is obtained, where the first uncertainty is due to the accuracy of the inelastic cross-section used by both CDF and D0, and the second uncertainty is due to D0 sources. The recorded luminosity for the highest E{sub T} jet trigger is L{sub rec}=9.2±0.4fb{sup ?1}, with a relative uncertainty of 4.3%.

Casey, B.C.K. [Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States); Corcoran, M. [Rice University, Houston, Texas 77005 (United States); DeVaughan, K. [University of Nebraska, Lincoln, Nebraska 68588 (United States); Enari, Y. [LPNHE, Universités Paris VI and VII, CNRS/IN2P3, Paris (France); Gallas, E. [Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States); Katsanos, I., E-mail: katsanos@fnal.gov [University of Nebraska, Lincoln, Nebraska 68588 (United States); Linnemann, J. [Michigan State University, East Lansing, Michigan 48824 (United States); Orduna, J. [Rice University, Houston, Texas 77005 (United States); Partridge, R. [Brown University, Providence, Rhode Island 02912 (United States); Prewitt, M. [Rice University, Houston, Texas 77005 (United States); Schellman, H. [Northwestern University, Evanston, Illinois 60208 (United States); Snow, G.R. [University of Nebraska, Lincoln, Nebraska 68588 (United States); Verzocchi, M. [Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States)

2013-01-11

82

Luminosity Monitoring in ATLAS with MPX Detectors  

OpenAIRE

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...

Sopczak, Andre

2013-01-01

83

Magnetic activity and variations in solar luminosity  

International Nuclear Information System (INIS)

The cause of luminosity variations over sunspot cycles has been investigated. Intense magnetic fields in sunspots hamper convection locally and a model is proposed here which indicates how strong magnetic fields at the base of the convective zone can alter the local convection. The resulting changes in thermal energy are large enough to produce variations of order 0.1% in the solar luminosity over the 11-yr sunspot cycle. (U.K.)

84

BDS tuning and Luminosity Monitoring in CLIC  

OpenAIRE

The emittance preservation in the Beam Delivery System (BDS) is one of the major challenges in CLIC. The fast detuning of the final focus optics requires an on-line tuning procedure in order to keep luminosity close to the maximum. Different tuning techniques have been applied to the CLIC BDS and in particular to the Final Focus System (FFS) in order to mitigate static and dynamic imperfections. Some of them require a fast luminosity measurement. Here we study the possibilit...

Dalena, B.; Barranco, J.; Latina, A.; Marin, E.; Pfingstner, J.; Schulte, D.; Snuverink, J.; Tomas, R.; Zamudio, G.

2012-01-01

85

Luminosity increasing in the PETRA storage ring  

International Nuclear Information System (INIS)

To improve the beam luminosity of PETRA storage ring, introduced are sections with the minimal #betta#-function value of the focusing quadrupoles. The sections are intended for compressing the beam in four regions of interaction. The beam lifetime has not shortened, other parameters have remained the same, whereas the luminosity has in-- creased three times. The solution found allowed one to completely exclude the compensating coils and install new quadrupoles

86

The luminosity constraint on solar neutrino fluxes  

OpenAIRE

A specific linear combination of the total solar neutrino fluxes must equal the measured solar photon luminosity if nuclear fusion reactions among light elements are responsible for solar energy generation. This luminosity constraint, previously used in a limited form in testing the no neutrino oscillation hypothesis, is derived in a generality that includes all of the relevant solar neutrino fluxes and which is suitable for analyzing the results of many different solar neut...

Bahcall, John N.

2001-01-01

87

Detectors for absolute luminosity measurement at DAFNE  

International Nuclear Information System (INIS)

Since the second half of year 2007, the Frascati ?- factory DAFNE has been running with an upgraded interaction region in order to test the crabbed waist collision scheme. The aim is to reach a large improvement of the specific luminosity of the accelerator. We describe the various detectors realized to have a reliable and fast absolute luminosity measurement, the on-line analysis in order to get rid of the machine background contribution, and the performances of the system.

88

Detectors for absolute luminosity measurement at DAFNE  

Energy Technology Data Exchange (ETDEWEB)

Since the second half of year 2007, the Frascati {Phi}- factory DAFNE has been running with an upgraded interaction region in order to test the crabbed waist collision scheme. The aim is to reach a large improvement of the specific luminosity of the accelerator. We describe the various detectors realized to have a reliable and fast absolute luminosity measurement, the on-line analysis in order to get rid of the machine background contribution, and the performances of the system.

Valente, P., E-mail: paolo.valente@roma1.infn.i [INFN Roma, Rome (Italy); Boscolo, M.; Bossi, F.; Buonomo, B.; Mazzitelli, G.; Murtas, F.; Sensolini, G.; Raimondi, P. [INFN LNF, Frascati (Italy); Arnaud, N.; Breton, D.; Burmistrov, L.; Stocchi, A.; Variola, A.; Viaud, B. [LAL, Orsay (France); Branchini, P. [INFN Roma Tre, Rome (Italy); Schioppa, M. [INFN Cosenza, Rende (Italy)

2010-05-21

89

Black Hole Jets at the Lowest Luminosities  

Science.gov (United States)

Both transient stellar mass black hole X-ray binaries (BHXBs) and supermassive black holes (SMBHs) spend the majority of their lives accreting at very low rates relative to their Eddington luminosities, in the so-called quiescent regime (Eddington ratios lxlow-luminosity end of black hole accretion (which is arguably the most common accretion regime), and thereby improve the utility of using radiative signatures to learn about highly sub-Eddington black holes across the entire black hole mass scale.

Plotkin, Richard; Gallo, Elena; Jonker, Peter G; Markoff, Sera; Homan, Jeroen; Miler-Jones, James; Russell, David M; Drappeau, Samia

2014-08-01

90

Luminosity spectrum reconstruction at linear colliders  

Energy Technology Data Exchange (ETDEWEB)

A good knowledge of the luminosity spectrum is mandatory for many measurements at future e{sup +}e{sup -} 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. 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. (orig.)

Poss, Stephane; Sailer, Andre [CERN, Geneva 23 (Switzerland)

2014-04-15

91

The D0 experiment's integrated luminosity for Tevatron Run IIa  

Energy Technology Data Exchange (ETDEWEB)

An essential ingredient in all cross section measurements is the luminosity used to normalize the data sample. In this note, we present the final assessment of the integrated luminosity recorded by the D0 experiment during Tevatron Run IIa. The luminosity measurement is derived from hit rates from the products of inelastic proton-antiproton collisions registered in two arrays of scintillation counters called the luminosity monitor (LM) detectors. Measured LM rates are converted to absolute luminosity using a normalization procedure that is based on previously measured inelastic cross sections and the geometric acceptance and efficiency of the LM detectors for registering inelastic events. During Run IIa, the LM detector performance was improved by a sequence of upgrades to the electronic readout system and other factors summarized in this note. The effects of these changes on the reported luminosity were tracked carefully during the run. Due to the changes, we partition the run into periods for which different conversions from measured LM rates to absolute luminosity apply. The primary upgrade to the readout system late in Run IIa facilitated a reevaluation of the overall normalization of the luminosity measurement for the full data sample. In this note, we first review the luminosity measurement technique employed by D0. We then summarize the changes to the LM system during Run IIa and the corresponding normalization adjustments. The effect of the adjustments is to increase D0's assessment of its recorded integrated luminosity compared to what was initially reported during Run IIa. The overall increase is 13.4% for data collected between April 20, 2002 (the beginning of Run IIa data used for physics analysis) and February 22, 2006 (the end of Run IIa).

Andeen, T.; Casey, B.C.K.; DeVaughan, K.; Enari, Y.; Gallas, E.; Krop, D.; Partridge, R.; Schellman, H.; Snow, G.R.; Yacoob, S.; Yoo, H.D.; /Brown U. /Fermilab /Indiana

2007-04-01

92

Dependence of Fanaroff-Riley break of radio galaxies on luminosity and redshift  

Science.gov (United States)

We investigate the dependence of the Fanaroff-Riley (FR) 1/2 dichotomy of radio galaxies on their luminosities and redshifts. Because of a very strong redshift-luminosity correlation (Malmquist bias) in a flux-limited sample, any redshift-dependent effect could appear as a luminosity-related effect and vice versa. A question could then arise—do all the morphological differences seen in the two classes (FR 1 and 2 types) of sources, usually attributed to the differences in their luminosities, could as well be primarily a redshift-dependent effect? A sharp break in luminosity, seen among the two classes, could after all reflect a sharp redshift dependence due to a rather critical ambient density value at some cosmic epoch. A doubt on these lines does not seem to have been raised in past and things have never been examined with this particular aspect in mind. We want to ascertain the customary prevalent view in the literature that the systematic differences in the two broad morphology types of FR 1 and 2 radio galaxies are indeed due to the differences in their luminosities, and not due to a change in redshift. Here we investigate the dependence of FR 1/2 dichotomy of radio galaxies on luminosity and redshift by using the 3CR sample, where the FR 1/2 dichotomy was first seen, supplemented by data from an additional sample (MRC), that goes about a factor of 5 or more deeper in flux-density than the original 3CR sample. This lets us compare sources with similar luminosities but at different redshifts as well as examine sources at similar redshifts but with different luminosities, thereby allowing us a successful separation of the otherwise two intricately entangled effects. We find that the morphology type is not directly related to redshift and the break between the two types of morphologies seems to depend only upon the radio luminosity.

Singal, Ashok K.; Rajpurohit, Kamlesh

2014-09-01

93

Cosmological simulations of black hole growth: AGN luminosities and downsizing  

Science.gov (United States)

In this study, we present a detailed, statistical analysis of black hole 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, black hole growth and associated feedback processes from both Type II/Ia supernovae and AGN. We consider two simulation runs, one with a large comoving volume of (500 Mpc)3 and one with a smaller volume of (68 Mpc)3 but with a factor of almost 20 higher mass resolution. We compare the predicted statistical properties of AGN with results from large observational surveys. Consistently with previous results, our simulations can widely match observed black hole properties of the local Universe. Furthermore, our simulations can successfully reproduce the evolution of the bolometric AGN luminosity function for both the low-luminosity and the high-luminosity end up to z = 3.0, only at z = 1.5-2.5, the low-luminosity end is overestimated by up to 1 dex. In addition, the smaller but higher resolution run is able to match the observational data of the low bolometric luminosity end at higher redshifts z = 3-4. We also perform a direct comparison with the observed soft and hard X-ray luminosity functions of AGN, including an empirical correction for a torus-level obscuration, and find a similarly good agreement. These results nicely demonstrate that the observed `antihierarchical' trend in the AGN number density evolution (i.e. the number densities of luminous AGN peak at higher redshifts than those of faint AGN) is self-consistently predicted by our simulations. Implications of this downsizing behaviour on active black holes, their masses and Eddington ratios are discussed. Overall, the downsizing behaviour in the AGN number density as a function of redshift can be mainly attributed to the evolution of the gas density in the resolved vicinity of a (massive) black hole (which is depleted with evolving time as a consequence of star formation and AGN feedback).

Hirschmann, Michaela; Dolag, Klaus; Saro, Alexandro; Bachmann, Lisa; Borgani, Stefano; Burkert, Andreas

2014-08-01

94

Luminosity evolution in gamma-ray bursts  

International Nuclear Information System (INIS)

We estimate the luminosity evolution and formation rate for over a 900 BATSE GRBs by using redshift and luminosity data calculated by Band, Norris, and Bonnell (Apj, 613 (2004) 484B) 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 far beaming angle evolution in the current sample of GRBs with known redshift, suggesting that this increase in luminosity cannot be due to an evolution or the collimation of gamma-ray emission. The resulting luminosity function is well fit with a single power law of index L'-1.5, which is intermediate between the values predicted by the k = 2 power law and Gaussian structured jet models. We also find that the GRB comoving rate density rises steeply with a broad peak between 1 3. This rate density qualitatively matches the current estimates of the star formation rate at high redshifts, favoring a short lived mashigh redshifts, favoring a short lived massive star progenitor model, or a binary model with a short delay between the formation of the compact object and the eventual merger

95

Luminosity of serendipitous x-ray QSOs  

International Nuclear Information System (INIS)

We have identified the optical counterparts of 47 serendipitously discovered Einstein Observatory X-ray sources with previously unreported quasi-stellar objects. The mean ratio of X-ray to optical luminosity of this sample agrees reasonably well with that derived from X-ray observations of previously known QSOs. However, despite the fact that our limiting magnitude V = 18.5 should permit detection of typical QSOs (i.e., M/sub c/ = -26) to z = 0.9, the mean redshift of our sample is only z = 0.42 Thus the mean luminosity of these objects, M/sub c/ = -24, differs significantly from that of previous QSO surveys with similar optical thresholds. The existence of large numbers of these lower luminosity QSOs which are difficult to discover by previous selection techniques, provides observational confirmation of the steep luminosity function inferred indirectly from optical counts. However, possible explanations for the lack of higher luminosity QSOs in our sample prove even more interesting. If one accepts the global value of the X-ray to optical luminosity ratio proposed by Zamorani et al, and Ku, Helfand, and Lucy, then reconciliation of this ratio with our observations severely constrains the QSO space density and luminosity functions. Alternatively, the ''typical'' QSO-a radio quiet, high redshift (z>1), optically luminous but not superluminous (M/sub c/> or =-27) object-may not be a strong X-ray source. This inference is not in conflict with existing results from Einsteconflict with existing results from Einstein X-ray surveys of preselected QSOs, which also fail to detect such objects. The contribution of QSOs to the diffuse X-ray background radiation is therefore highly uncertain, but may be quite small. Current X-ray data probably do not place significant constraints on the optical number counts of faint QSOs

96

Using Spectral Flux Ratios to Standardize SN Ia Luminosities  

CERN Document Server

We present a new method to standardize Type Ia supernova (SN Ia) luminosities to ~<0.13 magnitudes using flux ratios from a single flux-calibrated spectrum per SN. Using Nearby Supernova Factory spectrophotomery of 58 SNe Ia, we performed an unbiased search for flux ratios which correlate with SN Ia luminosity. After developing the method and selecting the best ratios from a training sample, we verified the results on a separate validation sample and with data from the literature. We identified multiple flux ratios whose correlations with luminosity are stronger than those of light curve shape and color, previously identified spectral feature ratios, or equivalent width measurements. In particular, the flux ratio R(642/443) = F(642 nm) / F(443 nm) has a correlation of 0.95 with SN Ia absolute magnitudes. Using this single ratio as a correction factor produces a Hubble diagram with a residual scatter standard deviation of 0.125 +- 0.011 mag, compared with 0.161 +- 0.015 mag when fit with the SALT2 light cur...

Bailey, S; Antilogus, P; Aragon, C; Baltay, C; Bongard, S; Buton, C; Childress, M; Chotard, N; Copin, Y; Gangler, E; Loken, S; Nugent, P; Pain, R; Pécontal, E; Pereira, R; Perlmutter, S; Rabinowitz, D; Rigaudier, G; Runge, K; Scalzo, R; Smadja, G; Swift, H; Tao, C; Thomas, R C; Wu, C

2009-01-01

97

EU supports the LHC high-luminosity study  

CERN Multimedia

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...

CERN Bulletin

2011-01-01

98

Luminosity-Distances of IUE observed Active Galaxies  

Science.gov (United States)

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.

Doddamani, Vijayakumar H.; Vedavathi, P.

2014-07-01

99

Intrinsic ?-ray luminosity, black hole mass, jet and accretion in Fermi blazars  

Science.gov (United States)

We have analysed a large sample of clean blazars detected by Fermi Large Area Telescope (LAT). Using the literature and calculation, we obtained intrinsic ?-ray luminosity excluding beaming effect, black hole mass, broad-line luminosity (used as a proxy for disc luminosity), jet kinetic power from `cavity' power and bulk Lorentz factor for parsec-scale radio emission, and studied the distributions of these parameters and relations between them. Our main results are as follows. (i) After excluding beaming effect and redshift effect, intrinsic ?-ray luminosity with broad-line luminosity, black hole mass and Eddington ratio have significant correlations. Our results confirm the physical distinction between BL Lacs and FSRQs. (ii) The correlation between broad-line luminosity and jet power is significant which supports that jet power has a close link with accretion. Jet power depends on both the Eddington ratio and black hole mass. We also obtain logLBLR ˜ (0.98 ± 0.07)logPjet for all blazars, which is consistent with the theoretical predicted coefficient. These results support that jets are powered by energy extraction from both accretion and black hole spin (i.e. not by accretion only). (iii) For almost all BL Lacs, Pjet > Ldisc; for most of FSRQs, Pjet < Ldisc. The `jet-dominance' (parametrized as P_jet/L_disc) is mainly controlled by the bolometric luminosity. Finally, the radiative efficiency of ?-ray and properties of TeV blazars detected by Fermi LAT were discussed.

Xiong, D. R.; Zhang, X.

2014-07-01

100

ATLAS Upgrades Towards the High Luminosity LHC  

CERN Document Server

After successful LHC operation at the center-of-mass energy of 7 TeV in 2011, the LHC is scheduled to deliver even more data in 2012 at 8 TeV. Meanwhile, plans are actively advancing for a series of upgrades, culminating roughly 10 years from now in the high luminosity LHC (HL-LHC) project, delivering of order five times the LHC nominal instantaneous luminosity along with luminosity levelling. The final goal is to extend the data set from about 300fb-1 expected for LHC running to 3000 fb-1 by around 2030. Current planning in ATLAS also has significant upgrades to the detector during the consolidation of the LHC to reach full LHC energy and further upgrades to accommodate running already beyond nominal luminosity this decade. The challenge of coping with HL-LHC instantaneous and integrated luminosity, along with the associated radiation levels, requires further major changes to the ATLAS detector. The designs are developing rapidly for an all-new inner-tracker, significant upgrades in the calorimeter and muon ...

Zhu, H; The ATLAS collaboration

2012-01-01

101

The K-Band Galaxy Luminosity Function  

CERN Document Server

We measured the K-band luminosity function using a complete sample of 4192 morphologically-typed 2MASS galaxies with 7 -0.5) galaxies have similarly shaped luminosity functions, alpha_e=-0.92+/-0.10 and alpha_l=-0.87+/-0.09. The early-type galaxies are brighter, M_*e=-23.53+/-0.06 mag compared to M_*l=-22.98\\pm0.06 mag, but less numerous, n_*e=(0.0045+/-0.0006)h^3/Mpc^3 compared to n_*l=(0.0101+/-0.0013)h^3/Mpc^3 for H_0=100h km/s Mpc, such that the late-type galaxies slightly dominate the K-band luminosity density, j_late/j_early=1.17+/-0.12. Our morphological classifications are internally consistent, consistent with previous classifications and lead to luminosity functions unaffected by the estimated uncertainties in the classifications. These luminosity functions accurately predict the K-band number counts and redshift distributions for K < 18 mag, beyond which the results depend on galaxy evolution and merger histories.

Kochanek, C S; Falco, E E; Huchra, J P; Mader, J; Jarrett, T H; Chester, T J; Cutri, R M; Schneider, S E

2000-01-01

102

ATLAS Upgrades Towards the High Luminosity LHC  

CERN Document Server

After successful LHC operation at the center-of-mass energy of 7 and 8 TeV in 2011 and 2012, plans are actively advancing for a series of upgrades, culminating roughly 10 years from now in the high luminosity LHC (HL-LHC) project, delivering of order five times the LHC nominal instantaneous luminosity along with luminosity levelling. The final goal is to extend the data set from about few hundred fb?1 expected for LHC running to 3000 fb?1 by around 2030. Current planning in ATLAS also has significant upgrades to the detector during the consolidation of the LHC to reach full LHC energy and further upgrades to accommodate running already beyond nominal luminosity this decade. The challenge of coping with HL-LHC instantaneous and integrated luminosity, along with the associated radiation levels, requires further major changes to the ATLAS detector. The designs are developing rapidly for an all-new inner-tracker, significant upgrades in the calorimeter and muon systems, as well as improved triggers and data a...

Cinca, D; The ATLAS collaboration

2014-01-01

103

ATLAS Upgrades Towards the High Luminosity LHC  

CERN Document Server

After successful LHC operation at 7 TeV in 2011, the LHC is scheduled to deliver even more data in 2012. Meanwhile, plans are actively advancing for a series of upgrades, culminating roughly 10 years from now in the high luminosity LHC (HL-LHC) project, delivering of order five times the LHC nominal instantaneous luminosity along with luminosity levelling. The final goal is to extend the data set from about 300 fb-1 expected for LHC running to 3000 fb-1 by around 2030. Current planning in ATLAS also has significant upgrades to the detector during the consolidation of the LHC to reach full LHC energy and further upgrades to accommodate running already beyond nominal luminosity this decade. The challenge of coping with HL-LHC instantaneous and integrated luminosity, along with the associated radiation levels, requires further major changes to the ATLAS detector. The designs are developing rapidly for an all-new inner-tracker, significant upgrades in the calorimeter and muon systems, as well as improved triggers...

Elsing, M; The ATLAS collaboration

2012-01-01

104

The stellar mass function at low luminosities  

International Nuclear Information System (INIS)

The author has combined the most recent studies of the stellar luminosity function to derive the mass function for stars in the mass range 1.0 > M/M solar mass > 0.08. The analysis shows the importance of using bolometric magnitudes in investigations of cool, late-type stars. The well established 'Wielen dip' at Msub(V) approx. = + 7 carries over into the bolometric function, which peaks at Msub(bol) approx. = + 9.5. However evidence is found for a second minimum at Msub(bol) approx. = + 12.5 and a subsequent rise to fainter luminosities. The stellar mass-luminosity relation is poorly defined at these luminosities, but the continuity of the HR diagram provides a strong argument that none of the isolated low-luminosity stars found to date are brown dwarfs. Under this interpretation, the observed mass density locally is approx. 0.09 M solar mass pc-3 and the missing mass remains unfound. (author)

105

CLIC Post-Collision Line Luminosity Monitoring  

CERN Document Server

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.

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

2011-01-01

106

ATLAS Upgrades Towards the High Luminosity LHC  

CERN Document Server

With the LHC having successfully collected data at center-of-mass energies of sqrt{s} = 7/8 TeV, plans are actively advancing for a series of upgrades leading eventually to about five times the LHC design luminosity some 10-years from now in the High-Luminosity LHC (HL-LHC) project. Coping with the high luminosity and the corresponding very high particle density will require significant changes to the ATLAS detector. Designs are developing rapidly for a replacement for the inner tracker, great changes in the calorimeter and muon systems, as well as improved triggers. This article summarizes the environment expected at the HL-LHC and the status of various improvements to the ATLAS detector.

Zhu, H; The ATLAS collaboration

2013-01-01

107

X-ray spectral state is not correlated with luminosity in Holmberg II X-1  

CERN Document Server

The ultraluminous X-ray source (ULX) Holmberg II X-1 has been observed over 4 months in 2009/2010 by the Swift observatory. The source luminosity varied by a factor of up to 14, reaching a maximum 0.3-10 keV luminosity of ~3.0E40 erg/s. The spectral properties do not vary much over these 4 months, with only a slight monotonic increase of the hardness ratio with the count rate. This means that the erratic flaring activity of the source is not associated with spectral changes, as seen in other ULXs. Conversely, comparison with data obtained by Swift in 2006 shows a completely different picture: while at a luminosity also seen in the 2009/2010 data, the source appears with a hard spectrum. Thus, it appears that, as in Galactic black hole binaries, spectral states in this ULX are not determined only by the X-ray luminosity.

Grisé, Fabien; Feng, Hua; Kajava, Jari; Farrell, Sean; 10.1088/2041-8205/724/2/L148

2010-01-01

108

Description of nuclear interaction in Keldysh diagram technique and neutrino luminosity of neutron stars  

International Nuclear Information System (INIS)

Keldysh's diagram technique is formulated for description of equilibrium and nonequilibrium nuclear systems. Nuclear interaction is built within the theory of finite Fermi systems. The formalism is applied to calculating probabilities of various processes. Possibilities of the approach are shown in the calculation of the luminosity of the main reactions which contribute to cooling of neutron stars. The luminosity is calculated produced by the process nn ? npe?-bar which proceeds essentially differently in dense and dilute nucleon medium. The dependence of the luminosity upon the nucleon-nucleon correlation factor is analyzed. The formalism is applied to systems with pairing. Contributions is calculated introduced to the luminosity by reactions npaired ? n??-bar and ppaired ? p??-bar which proceed only in the presence of nucleon pairing. Consequences of the results are discussed in the scenario of cooling of the neutron stars

109

Extinction in Nebular Luminosities & Star Formation Rate of Disk Galaxies: Inclination Correction  

CERN Document Server

Star formation is one of the most important processes in galaxy formation. The luminosity of Halpha recombination and [OII] forbidden emissions remain to be most used in measuring formation rate of massive stars in galaxies. Here we report the inclination dependency of continuum-subtracted and aperture-corrected nebular luminosities, including Halpha, Hbeta, Hgamma, [OII], [NII], of disk-dominated galaxies in the local universe. Their luminosities decrease by a factor of three from face-on to edge-on (axis ratio limit = 0.17) orientations. This dependence is deduced to be caused by extinction due to diffuse dust within the disks with an amplitude of 1.2 mag. The line-luminosity--inclination relation provides a novel way to remove extinction in emission lines and present star formation rate of disk galaxies out to redshift of 1.6.

Yip, Ching-Wa

2011-01-01

110

Offline Software for the PANDA Luminosity Detector  

Science.gov (United States)

In 2018 data taking for hadronphysics facility PANDA is planned to commence. It will be build at the antiproton accelerator HESR, which itself is a part of the FAIR complex (GSI, Darmstadt, Germany). The luminosity at PANDA will be measured by a dedicated sub-detector, which will register scattered antiproton tracks from pp elastic scattering. From a software point of view, the Luminosity Detector is a tracking system. Therefore the most of its offline software parts are typical for a track reconstruction. The basic concept and Monte Carlo based performance studies of each reconstruction step is presented in this paper.

Karavdina, A.; Denig, A.; Feldbauer, F.; Jasinski, P.; Leithoff, H.; Michel, M.; Motzko, C.; Pflüger, S.; Weber, T.; Fritsch, M.

2014-06-01

111

Luminosity levelling techniques for the LHC  

CERN Document Server

We present the possibilities for doing luminosity levelling at the LHC. We explore the merits and drawbacks of each option and briefly discuss the operational implications. The simplest option is levelling with an offset between the two beams. Crab cavities may also be used for levelling, as may a squeezing of the beam. There is also the possibility of using the crossing angle in order to do luminosity levelling. All of these options are explored, for the LHC and other possible new projects, together with their benefits and drawbacks.

Muratori, B

2014-01-01

112

The Local Luminosity Function at 25 Microns  

OpenAIRE

The local luminosity function at 25 $\\mu$m provides the basis for interpreting the results of deep mid-infrared surveys planned or in progress with space astrophysics missions including ISO, WIRE and SIRTF. We have selected a sample of 1458 galaxies from the IRAS Faint Source Survey with a flux density limit of 250 mJy at 25 $\\mu$m. The local luminosity function is derived using both parametric and non-parametric maximum-likelihood techniques, and the classical $1/V_{max}$ e...

Shupe, David L.; Fang, Fan; Hacking, Perry B.; Huchra, John P.

1998-01-01

113

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.)

114

Academic Training - LHC luminosity upgrade: detector challenges  

CERN Multimedia

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 ...

Françoise Benz

2006-01-01

115

Phase Space Constraints on Neutrino Luminosities  

CERN Document Server

While the importance of phase space constraints for gravitational clustering of neutrinos (which are fermions) is well recognized, the explicit use of such constraints to limit neutrino emission from ultra energetic sources has not been stressed. Special and general relativistic phase space constraints are shown to limit neutrino luminosities in compact sources in various situations.

Sivaram, C; Samartha, C A

2007-01-01

116

Funnel stability and VLBI-jet luminosity  

International Nuclear Information System (INIS)

The stability of the jet-funnel interface in thick disc models is investigated. In particular an analysis is made of the circumstances in which the growth of Kelvin-Helmholtz instabilities can destroy the jet-funnel configuration, and the expected luminosity emitted at the top of the funnel from conversion of bulk kinetic energy into radiation via turbulent cascade processes. (author)

117

Jet spectrometer for SSC energies and luminosities  

International Nuclear Information System (INIS)

A limited solid angle (?theta = ?phi = +-0.8 radians) spectrometer designed to study high transverse momentum (p/sub T/) jets at SSC energies and luminosities are described. The reasoning for its overall size and the particular type of each detector component is explained. Trigger rates for two jet production, expected from QCD, as well as number of electronic channels are listed

118

Spatial and luminosity distributions of galactic satellites  

CERN Document Server

We investigate the luminosity functions (LFs) and projected number density profiles of galactic satellites around isolated primaries of different luminosities. We measure these quantities for model satellites placed into the Millennium and Millennium II dark matter simulations by the GALFORM semi-analytic galaxy formation model for different bins of primary galaxy magnitude and we investigate their dependence on satellite luminosity. We compare our model predictions to the data of Guo et al. from the Sloan Digital Sky Survey Data Release 8 (SDSS DR8). First, we use a mock light-cone catalogue to verify that the method we used to count satellites in the SDSS DR8 is unbiased. We find that the radial distributions of model satellites are similar to those around comparable primary galaxies in the SDSS DR8, with only slight differences at low luminosities and small projected radii. However, when splitting the satellites by colour, the model and SDSS satellite systems no longer resemble one another, with many red m...

Guo, Quan; Eke, Vincent; Frenk, Carlos; Helly, John

2013-01-01

119

Intrinsic $\\gamma$-ray luminosity, black hole mass, jet and accretion in Fermi blazars  

CERN Document Server

We have analyzed a large sample of clean blazars detected by Fermi Large Area Telescope (LAT). Using literature and calculation, we obtained intrinsic $\\gamma$-ray luminosity excluding beaming effect, black hole mass, broad-line luminosity (used as a proxy for disk luminosity), jet kinetic power from "cavity" power and bulk Lorentz factor for parsec-scale radio emission, and studied the distributions of these parameters and relations between them. Our main results are as follows. (i) After excluding beaming effect and redshift effect, intrinsic $\\gamma$-ray luminosity with broad line luminosity, black hole mass and Eddington ratio have significant correlations. Our results confirm the physical distinction between BL Lacs and FSRQs. (ii) The correlation between broad line luminosity and jet power is significant which supports that jet power has a close link with accretion. Jet power depends on both the Eddington ratio and black hole mass. We also obtain $LogL_{\\rm BLR}\\sim(0.98\\pm0.07)Log P_{\\rm jet}$ for all ...

Xiong, Dingrong

2014-01-01

120

The cross-correlation between galaxies of different luminosities and Colors  

CERN Document Server

We study the cross-correlation between galaxies of different luminosities and colors, using a sample selected from the SDSS Dr 4. Galaxies are divided into 6 samples according to luminosity, and each of these samples is divided into red and blue subsamples. Projected auto-correlation and cross-correlation is estimated for these subsample. At projected separations r_p > 1\\mpch, all correlation functions are roughly parallel, although the correlation amplitude depends systematically on luminosity and color. On r_p 1\\mpch for each subsample using its auto-correlation function and cross-correlation functions. The relative bias factors obtained from different methods are similar. For blue galaxies the luminosity-dependence of the relative bias is strong over the luminosity range probed (-23.0luminosities below L^*. To examine whether a significant stochastic/nonlinear component exists in the bias relation, we study the...

Wang, Y; Mo, H J; Van den Bosch, F C; Wang, Yu; Yang, Xiaohu; Bosch, Frank C. van den

2007-01-01

121

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

International Nuclear Information System (INIS)

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+e? 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=1033s?1cm?2 value. Two ways extending the method to the large pile-up periods corresponding to higher instantaneous luminosities are proposed

122

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

123

LIGHT and LUMINOSITY, from Einstein to LHC  

CERN Document Server

After an introduction on the concept of light in physics, this talk will focus on CERN’s High Luminosity LHC project, aiming at extending the discovery potential of CERN’s 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.

CERN. Geneva; Prof. ROSSI, Lucio

2015-01-01

124

LHC operation at higher energy and luminosity  

CERN Document Server

The Large Hadron Collider (LHC) at CERN (Geneva) was commissioned and operated in the years 2009-2013 up to a beam energy of 4 TeV. A peak luminosity of 0.77 · 1034 cm?2s?1 was reached and an integrated luminosity of around 29 fb?1 was delivered to both ATLAS and CMS. This performance allowed the discovery of a scalar boson. The LHC is presently in a shutdown phase dedicated to consolidation and maintenance that will allow the restart of beam operation in early 2015 at an increased beam energy of 6.5 to 7TeV. Maximum acceptable pileup, effectiveness of electron-cloud scrubbing, and fast loss events are some of the issues that will shape the choice of operational parameters, cycle setup, and the commissioning strategy. The baseline choices and options for the restart after the shutdown are presented. In addition the roadmap for future performance upgrades is sketched.

Papotti, G

2013-01-01

125

Solar gravitational energy and luminosity variations  

CERN Document Server

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...

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

2009-01-01

126

Luminosity functions for asymptotic giant branch stars  

International Nuclear Information System (INIS)

To understand the evolution of carbon and oxygen rich asymptotic giant branch (AGB) stars it is important to observationally establish the relations between parameters such as luminosity, age and metallicity. The existence of luminous (brighter than the top of the first giant branch) AGB stars in clusters in the Magellanic Clouds provides a nearly ideal situation in which these relations can be determined. Although metallicities and main sequence turn-off ages are known for only a fraction of the clusters, the ranking scheme devised by Searle, et al. (1980) indicates that age and metallicity are closely related to one another. A search has been completed and infrared photometry obtained for luminous AGB stars in 35 clusters. This paper discusses the bolometric luminosities of the C and M stars found. (Auth.)

127

Luminosity indicators in dusty photoionized environments  

CERN Document Server

The luminosity of the central source in ionizing radiation is an essential parameter in a photoionized environment, and one of the most fundamental physical quantities one can measure. We outline a method of determining luminosity for any emission-line region using only infrared data. In dusty environments, grains compete with hydrogen in absorbing continuum radiation. Grains produce infrared emission, and hydrogen produces recombination lines. We have computed a very large variety of photoionization models, using ranges of abundances, grain mixtures, ionizing continua, densities, and ionization parameters. The conditions were appropriate for such diverse objects as H II regions, planetary nebulae, starburst galaxies, and the narrow and broad line regions of active nuclei. The ratio of the total thermal grain emission relative to H$\\beta$ (IR/H$\\beta$) is the primary indicator of whether the cloud behaves as a classical Strömgren sphere (a hydrogen-bounded nebula) or whether grains absorb most of the inciden...

Bottorff, M C; Momjian, E; Verner, E M; Vinkovic, D; Ferland, G J; Bottorff, Mark; Mothe, Joseph La; Momjian, Emmanuel; Verner, Ekaterina; Vinkovic', Dejan; Ferland, Gary

1998-01-01

128

RF TECHNIQUES FOR IMPROVED LUMINOSITY IN RHIC.  

Energy Technology Data Exchange (ETDEWEB)

The luminosity of the Relativistic Heavy Ion Collider has improved significantly [1] over the first three physics runs. A number of special rf techniques have been developed to facilitate higher luminosity. The techniques described herein include: an ultra low-noise rf source for the 197 MHz storage rf system, a frequency shift switch-on technique for transferring bunches from the acceleration to the storage system, synchronizing the rings during the energy ramp (including crossing the transition energy) to avoid incidental collisions, installation of dedicated 200 MHZ cavities to provide longitudinal Landau damping on the ramp, and the development of a bunch merging scheme in the Booster to increase the available bunch intensity from the injectors.

BRENNAN,J.M.BLASKIEWICZ,J.BUTLER,J.DELONG,J.FISCHER,W.HAYES,T.

2004-07-05

129

Shedding Light on the Galaxy Luminosity Function  

CERN Document Server

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 ...

Johnston, Russell

2011-01-01

130

Optimization of integrated luminosity in the Tevatron  

Energy Technology Data Exchange (ETDEWEB)

We present the strategy which has been used recently to optimize the performance of the Fermilab Tevatron proton-antiproton collider. We use a relatively simple heuristic model based on the antiproton production rate, which optimizes the number of antiprotons in a store in order to maximize the integrated luminosity. A store is terminated as soon as the target number of antiprotons is reached and the Tevatron quickly resets to load another store. Since this procedure was implemented, the integrated luminosity has improved by {approx} 35%. Other recent operational improvements include decreasing the shot setup time, and reducing beam-beam effects by making the proton and antiproton brightness more compatible, for example by scraping protons to smaller emittances.

Gattuso, C.; Convery, M.; Syphers, M.; /Fermilab

2009-04-01

131

Low luminosity galactic X-ray sources  

Science.gov (United States)

Models of soft X-ray emission from low-luminosity galactic X-ray sources are compared with currently available data. Emphasis is placed on disk population stars, irrespective of source temperatures spectral type, luminosity class, and age; and predictions of source temperatures and variability have been used to distinguish between the various models. It is tentatively found that the X-ray emission characteristics of late and early spectral types, and young and old stars, share many similarities; an economical explanation for this is the manifestation of coronal surface activity modulated by the stellar parameters that govern stellar magnetic activity (e.g., rotation). In some cases (such as for OB stars), a proper theory accounting for the heating of the coronal plasma does not exist.

Vaiana, G. S.

1981-01-01

132

Search for low-luminosity pulsars  

International Nuclear Information System (INIS)

We present the results of Phase I of the Princeton-NRAO pulsar survey, carried out at 390 MHz using the 92 m telescope at Green Bank, West Virginia. This search discovered 34 new pulsars and detected 49 previously known ones. As has been the case with all previous surveys, we found no pulsars with intrinsic luminosities less than 0.3 mJy kpc2. Because of the high sensitivity of the survey and its coverage of nearly 2 sr of sky, our results imply that such low-luminosity pulsars do not constitute a large portion of the total active pulsar population in the Galaxy. Also in common with previous surveys, the sensitivity of this one deteriorates rather quickly for pulse periods less than a few tenths of a second. We dicuss the extent to which this loss of sensitivity has biased the period distribution of known pulsars

133

Low-luminosity active galactic nuclei  

International Nuclear Information System (INIS)

The properties of low-luminosity active nuclei are summarized in an effort to determine the continuities which exist among classes of objects exhibiting nonstellar energy input. Questions are addressed which deal with the relations among the classes of active nuclei (low-ionization nuclei, weak Seyfert nuclei, composite objects and starbursts), their relation to star-forming nuclei, and how these objects differ from the high-luminosity classical Seyfert nuclei, radio galaxies and QSOs. It is suggested that starburst nuclei may evolve rapidly into compact configurations of collapsed remnants, which might further collapse into massive accretors. In contrast, some luminous active nuclei show surrounding star formation, indicating that nuclear activity may induce star formation in its environs. 129 references

134

Alternative high luminosity LHC matching section layout  

CERN Document Server

In the framework of the HL-LHC Upgrade project possible variants for the layout of the LHC matching section located in the high luminosity insertions are investigated. This layout is optimized to reduce the demand on the voltage of the crab cavities, it also improves the optics squeeze-ability, both in ATS [1] and non-ATS mode. Moreover the injection and transitions to collision optics are also discussed.

Dalena, B; Chancé, A; De Maria, R

2014-01-01

135

New luminosity component in 3c 48  

International Nuclear Information System (INIS)

The infrared emission from the quasar 3C 48 has a luminosity Lroughly-equal5 x 1012L/sub sun/ and dominates the power output of the quasar system. It is shown that the infrared emission, unlike that of most radio-loud quasars, is most likely not an extension of the radio emission of the quasar. It is argued that the infrared emission in 3C 48 is probably thermal radiation arising in a highly luminous galaxy surrounding the quasar

136

Verifying the Planetary Nebula Luminosity Function Method  

OpenAIRE

The planetary nebula luminosity function (PNLF) technique for determining distances to galaxies now has been applied to 34 galaxies, including 6 in the Virgo cluster and 3 in the Fornax cluster. Of these, 16 galaxies are late-type or spirals and presumably contain Cepheid variables useful for verifying the PNLF method. For 7 of these galaxies, Cepheid distances exist; the PNLF distances agree with the Cepheid distances within the dispersion of 8% and within a zero-point offs...

Jacoby, George

1996-01-01

137

Low EUV Luminosities Impinging on Protoplanetary Disks  

OpenAIRE

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 ...

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

2014-01-01

138

Luminosity measurements in ATLAS with MPX detectors  

International Nuclear Information System (INIS)

The ATLAS-MPX detectors are based on Medipix2 silicon devices designed by CERN for the detection of different types of radiation. These detectors are successfully operating in the ATLAS detector at 16 places and collect data independent of the ATLAS data-recording chain. Recently it has been recognized that these detectors are well suited for luminosity measurements. Results from these studies are presented.

139

A star of very low luminosity  

International Nuclear Information System (INIS)

The method of photometric parallax (Msub(V)/V-I relation) has been applied to a UK Schmidt Telescope field towards the South Galactic Pole to derive a kinematically unbiased luminosity function for low mass stars. The discovery of one such star, RG 0050-2722, which has an absolute magnitude Msub(V) approximately +19, and is 25 +- 6 pc from the Sun, is presented here. This is only the second star known to have Msub(V) >= +18. (author)

140

Axions and the white dwarf luminosity function  

Energy Technology Data Exchange (ETDEWEB)

The evolution of white dwarfs can be described as a simple cooling process. Recently, it has been possible to determine with an unprecedented precision their luminosity function, that is, the number of stars per unit volume and luminosity interval. Since the shape of the bright branch of this function is only sensitive to the average cooling rate, we use this property to check the possible existence of axions, a proposed but not yet detected weakly interacting particle. We show here that the inclusion of the axion emissivity in the evolutionary models of white dwarfs noticeably improves the agreement between the theoretical calculations and the observational white dwarf luminosity function, thus providing the first positive indication that axions could exist. Our results indicate that the best fit is obtained for m{sub a}cos{sup 2}beta approx = 2-6 meV, where m{sub a} is the mass of the axion and cos{sup 2}beta is a free parameter, and that values larger than 10 meV are clearly excluded.

Isern, J; Catalan, S [Institut de Ciencies de l' Espai (CSIC), Facultat de Ciencies, Campus UAB, 08193 Bellaterra (Spain); GarcIa-Berro, E; Torres, S, E-mail: isern@ieec.ca, E-mail: catalan@ieec.ca, E-mail: garcia@fa.upc.ed, E-mail: santi@fa.upc.ed [Institut d' Estudis Espacials de Catalunya (IEEC), c/Gran Capita 2-4, 08034 Barcelona (Spain)

2009-06-01

141

Axions and the white dwarf luminosity function  

International Nuclear Information System (INIS)

The evolution of white dwarfs can be described as a simple cooling process. Recently, it has been possible to determine with an unprecedented precision their luminosity function, that is, the number of stars per unit volume and luminosity interval. Since the shape of the bright branch of this function is only sensitive to the average cooling rate, we use this property to check the possible existence of axions, a proposed but not yet detected weakly interacting particle. We show here that the inclusion of the axion emissivity in the evolutionary models of white dwarfs noticeably improves the agreement between the theoretical calculations and the observational white dwarf luminosity function, thus providing the first positive indication that axions could exist. Our results indicate that the best fit is obtained for macos2? ? 2-6 meV, where ma is the mass of the axion and cos2? is a free parameter, and that values larger than 10 meV are clearly excluded.

142

Axions and the white dwarf luminosity function  

CERN Document Server

The evolution of white dwarfs can be described as a simple cooling process. Recently, it has been possible to determine with an unprecedented precision their luminosity function, that is, the number of stars per unit volume and luminosity interval. Since the shape of the bright branch of this function is only sensitive to the average cooling rate, we use this property to check the possible existence of axions, a proposed but not yet detected weakly interacting particle. We show here that the inclusion of the axion emissivity in the evolutionary models of white dwarfs noticeably improves the agreement between the theoretical calculations and the observational white dwarf luminosity function, thus providing the first positive indication that axions could exist. Our results indicate that the best fit is obtained for m_a cos^2beta ~ 2-6 meV, where m_a is the mass of the axion and cos^2beta is a free parameter, and that values larger than 10 meV are clearly excluded.

Isern, J; García-Berro, E; Torres, S

2008-01-01

143

K0 finding efficiencies in increasing luminosities  

International Nuclear Information System (INIS)

In early LHC running it is anticipated that experiments will obtain luminosities of 1032 cm-2sec-1, during which typically only one interaction per event will be obtained. But at higher luminosities, necessary for any Higgs and myriad other searches, experiments will have to deal with up to 50 distinct primary processes. Most will be minimum bias, and easily distinguished in terms of trigger. They can still, of course, confuse analysis of high PT events. When it comes to B events, the confusion even from minimum bias events becomes more acute, since B events are not open-quotes high PTclose quotes in this environment. The need for vertex discrimination, particularly in z, is well understood; however, a collateral effect - the increasing difficulty in finding tracks at all - has received little attention. The authors show the distribution of the K0 in the Pythia process B ? J/?K0 in the space ? vs. ?. Confusion in reconstructing the K0 is acute for many reasons, not the least of which is the way their pions are boosted forward, and even out of acceptance. Extra luminosity merely increases the problems in finding K0 's, so it must not be assumed that 1033 cm-2sec-1 is ten times better than 1032 cm-2sec-1

144

Ideas for a high luminosity muon physics detector with complete particle identification  

International Nuclear Information System (INIS)

Modifications of the existing EMC-NA9 spectrometer at the SPS muon beam by using a Time Projection Chamber (TPC) as vertex-detector and Ring Mage Cerenkov (RICH) counters allow at least a factor 5 increase in luminosity and provide complete hadron identification. The compactness of the new detectors gives space for future 4? coverage for neutral particle detection. (orig.)

145

Mini-? insertion and luminosity for the RHIC lattice  

International Nuclear Information System (INIS)

Requirement and implication of the mini-? insertion, where a pair of common quadrupoles are inserted between the interaction point and the frist beam crossing dipole, in RHIC lattice is studied. For the heavy ion operation, we find that ? = 1m can be achieved with a +-5m free space for experimental setup and /cflx /beta// = 500m. The beam size limitation is located at the second beam crossing dipole BC2, where 8cm coil i.d. is considered. When the machine is operating at the proton-heavy ion collision mode, these common quadrupoles should be removed physically in order to let both beams crossing the center line at 3.4 mrad. These mini-? insertion can increase the luminosity by a factor of 2 /approximately/ 3. For the proton-proton collision mode, we find that ? = 0.5m is also operable without the mini-? quadrupoles due to smaller emittance for the proton beam. The corresponding /cflx /beta// is 2400m. When the mini-? quads are used, ? = 0.25m can be achieved. The ultimate luminosity for the proton-proton collision is of the order of 1033/cm2 sec, which may be useful in the quest of the B physics studies. 3 refs., 3 figs., 3 tabs

146

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

International Nuclear Information System (INIS)

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. 67 references

147

Luminosity Lifetime at the LHC in 2012 Proton Physics  

CERN Document Server

In 2012, the LHC was operated at 4 TeV at top energy with beam parameters that allowed exceeding a peak instantaneous luminosity of 7500 µb^-1 s^-1 and a total of 23 fb^-1 integrated luminosity in the ATLAS and CMS experiments. This paper elaborates on the evolution of the LHC luminosity and luminosity lifetime during proton physics fills and through the year 2012. Bunch to bunch differences and the impact of different machine settings are highlighted.

Hostettler, M

2013-01-01

148

NLC Luminosity as a Function of Beam Parameters  

CERN Document Server

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.

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

2002-01-01

149

High-energy gamma-ray afterglows from low-luminosity gamma-ray bursts  

OpenAIRE

The observations of gamma-ray bursts (GRBs) such as 980425, 031203 and 060218, with luminosities much lower than those of other classic bursts, lead to the definition of a new class of GRBs -- low-luminosity GRBs. The nature of the outflow responsible for them is not clear yet. Two scenarios have been suggested: one is the conventional relativistic outflow with initial Lorentz factor of order of $\\Gamma_0\\ga 10$ and the other is a trans-relativistic outflow with $\\Gamma_0\\si...

He, Hao-ning; Wang, Xiang-yu; Yu, Yun-wei; Meszaros, Peter

2009-01-01

150

The Contribution of Normal, Dim, and Dwarf Galaxies to the Local Luminosity Density.  

Science.gov (United States)

From the Hubble Deep Field catalog recently presented by Driver et al., we derive the local (0.3low-luminosity low surface brightness galaxies outnumber Hubble types by a factor of approximately 1.4; however, their space density is not sufficient to explain the faint blue excess either by themselves or as faded remnants. In terms of the local luminosity density and galaxy dynamical mass budget, normal galaxies (i.e., the Hubble tuning fork) contribute 88% and 72%, respectively. This compares to 7% and 12% for dim galaxies and 5% and 16% for dwarf galaxies (within the above specified limits). PMID:10550280

Driver

1999-12-01

151

Upgrade of RHIC Vacuum Systems for High Luminosity Operation  

CERN Document Server

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...

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

2005-01-01

152

Faint-end Quasar Luminosity Functions from Cosmological Hydrodynamic Simulations  

CERN Document Server

We investigate the predictions for the faint-end quasar luminosity function (QLF) and its evolution using fully cosmological hydrodynamic simulations which self-consistently follow star formation, black hole growth and associated feedback processes. We find remarkably good agreement between predicted and observed faint end of the optical and X-ray QLFs (the bright end is not accessible in our simulated volumes) at z = 2 does not lead to an overestimate to the total X-ray background and its contribution is at most a factor of two larger than the unresolved fraction of the 2-8 keV background. Eve n though this could be explained by some yet undetected, perhaps heavily obscured faint quasar population, we show that our predictions for the faint sources at high redshifts (which are dominated by the low mass black holes) in the simulations are likely affected by resolution effects.

DeGraf, Colin; Springel, Volker

2009-01-01

153

Limitation of the luminosity by satellite resonances  

International Nuclear Information System (INIS)

Experimental and theoretical investigations have shown that the luminosity of the storage ring DORIS is limited by betatron-synchrotron resonances which are produced by the beam-beam interaction. The resonance frequencies are given by Qsub(?) = (p+rQsub(s))/q, where p, q, r are integers and Qsub(?) and Qsub(s) are the betatron and synchrotron wave numbers, respectively. It is shown that these resonances are caused by the crossing angle. Analytical investigations as well as computer simulations are in good agreement with measurements made at DORIS. The analytical investigation further shows that also a dispersion at the interaction point will produce these satellite resonances. (orig.)

154

Galaxy luminosity function: a new analytic expression  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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.

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

2004-06-01

155

The Luminosity Function of IRAS PSCz Galaxies  

OpenAIRE

We estimated the luminosity function (LF) of IRAS galaxies in the PSCz catalogue. The faint end of the PSCz LF is slightly steeper than that of the LF derived by Saunders et al. (1990; S90). Using an analytical form for the LF used by S90, we obtain the following parameters: \\alpha = 1.23 \\pm 0.04, L_*=(8.85 \\pm 1.75) \\times 10^8 h^{-2} L_\\odot, \\sigma =0.724 \\pm 0.010, and \\phi_* = (2.34 \\pm 0.30) \\times 10^{-2} h^3 Mpc^{-3}. We also examined the evolution in the sample by ...

Takeuchi, Tsutomu T.; Yoshikawa, Kohji; Ishii, Takako T.

2003-01-01

156

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

CERN Multimedia

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.

1977-01-01

157

Magnet Design of the 150 mm Aperture Low-? Quadrupoles for the High Luminosity LHC  

CERN Document Server

The High Luminosity LHC (HL-LHC) project is aimed at studying and implementing the necessary changes in the LHC to increase its luminosity by a factor five. Among the magnets that will be upgraded are the 16 superconducting low-? quadrupoles placed around the two high luminosity interaction regions (ATLAS and CMS experiments). In the current baseline scenario, these quadrupole magnets will have to generate a gradient of 140 T/m in a coil aperture of 150 mm. The resulting conductor peak field of more than 12 T will require the use of Nb3Sn superconducting coils. We present in this paper the HL-LHC low-? quadrupole design, based on the experience gathered by the US LARP program, and, in particular, we describe the support structure components to pre-load the coils, withstand the electro-magnetic forces, provide alignment and LHe containment, and integrate the cold mass in the LHC IRs.

Ferracin, P; Anerella, M; Borgnolutti, F; Bossert, R; Cheng, D; Dietderich, D R; Felice, H; Ghosh , A; Godeke, A; Izquierdo Bermudez, S; Fessia, P; Krave, S; Juchno, M; Perez, J C; Oberli, L; Sabbi, G; Todesco, E; Yu, M

2014-01-01

158

Quantifying the Luminosity Evolution in Gamma-ray Bursts  

CERN Document Server

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...

Kocevski, D; Kocevski, Daniel; Liang, Edison

2006-01-01

159

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

Science.gov (United States)

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 Pégase2 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 ˜0.5-0.9 mag. Based on observations obtained at the ESO VLT, Paranal, Chile; ESO programs 67.A-0175, 68.B-0088, and 69.A-0266.

Maier, C.; Meisenheimer, K.; Hippelein, H.

2004-05-01

160

LHC Report: A new luminosity record  

CERN Multimedia

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...

CERN Bulletin

2011-01-01

161

Short GRBs: Rates and luminosity function implications  

CERN Document Server

We compare the luminosity function and rate inferred from the BATSE short hard bursts (SHBs) peak flux distribution with the redshift and luminosity distributions of SHBs observed by Swift/HETE II. The Swift/HETE II SHB sample is incompatible with SHB population that follows the star formation rate. However, it is compatible with a distribution of delay times after the SFR. This would be the case if SHBs are associated with the mergers of double neutron star (DNS) systems. DNS may be ``primordial'' or can form dynamically by binary exchange interaction in globular clusters during core collapse. The implied SHB rates that we find range from \\sim 8 to \\sim 30h_(70)^3 Gpc^(-3)yr^(-1). This rate is a much higher than what was previously estimated and, when beaming is taken into account, it is comparable to the rate of neutron star mergers estimated from statistics of binary pulsars. If GRBs are produced in mergers the implied rate practically guarantees detection by LIGO II and possibly even by LIGO I.

Guetta, D

2006-01-01

162

Low EUV Luminosities Impinging on Protoplanetary Disks  

CERN Document Server

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...

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

2014-01-01

163

Avoiding spurious breaks in binned luminosity functions  

CERN Document Server

We show that using either the method of Page & Carrera or the well-known $1/V_a$ method to construct the binned luminosity function (LF) of a flux limited sample of Active Galactic Nuclei (AGN) can produce an artificial flattening (or steepening in the case of negative evolution) of the binned LF for bins intersected by the flux cutoff of the sample. This effect is more pronounced for samples with steep and strongly evolving parent LFs but is still present even for non-evolving LFs. As a result of this distortion of the true LF, fitting a model LF to binned data may lead to errors in the estimation of the parameters and may even prompt the erroneous use of broken power law functions. We compute the expected positions of apparent breaks in the binned LF. We show that these spurious breaks in the binned LFs can be avoided if the binning is done in the flux--redshift plane instead of the typically used luminosity--redshift plane. Binning in the flux--redshift plane can be used in conjunction with the binning...

Cara, Mihai

2008-01-01

164

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)

165

ROB performance in a high luminosity scenario  

CERN Document Server

The first layer of the CMS (Compact Muon Solenoid) DT (Drift Tube) readout system is built around the ROBs (Read Out Boards), which are responsible for the time measurement of the chamber signals to allow reconstruction of charged particle tracks with a resolution of 250 $\\mu m$ per cell. ROB boards have shown an excellent performance during LHC operation and are expected to continue their operation safely during all LHC Phase 1 up to 2022. Present LHC upgrades for Phase 2 foresee an increase of instantaneous luminosity up to $5 \\cdot 10^{34} ~ cm^{-2} \\cdot s^{-1}$ which will increase significantly the expected hit rate. Moreover, CMS is studying to increase the Level 1 Accept (\\emph{L1A}) latency of the trigger signal from 3.2 $\\mu s$ to 20 $\\mu s$ to allow including tracking subdetector information into the Level 1 trigger decision and also the \\emph{L1A} frequency from 100 kHz maximum to up to 1 MHz, in order to accommodate the increase of trigger rate due to the higher luminosity. ROB operation under suc...

Cela Ruiz, Jose Manuel

2014-01-01

166

The Low-Luminosity End of the Radius-Luminosity Relationship for Active Galactic Nuclei  

CERN Document Server

We present an updated and revised analysis of the relationship between the Hbeta 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 9 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 Hbeta time lag, which is assumed to yield the average Hbeta 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-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of alpha = 0.533 (+0.035/-0.033), consistent ...

Bentz, Misty C; Grier, Catherine J; Barth, Aaron J; Peterson, Bradley M; Vestergaard, Marianne; Bennert, Vardha N; Canalizo, Gabriela; De Rosa, Gisella; Filippenko, Alexei V; Gates, Elinor L; Greene, Jenny E; Li, Weidong; Malkan, Matthew A; Pogge, Richard W; Stern, Daniel; Treu, Tommaso; Woo, Jong-Hak

2013-01-01

167

The Galaxy Luminosity Function and Luminosity Density at Redshift z=0.1  

CERN Document Server

Using a catalog of 147,986 galaxy redshifts and fluxes from the Sloan Digital Sky Survey (SDSS) we measure the galaxy luminosity density at z=0.1 in five optical bandpasses corresponding to the SDSS bandpasses shifted to match their restframe shape at z=0.1. We denote the bands {0.1}{u}, {0.1}{g}, {0.1}{r}, {0.1}{i}, {0.1}{z}, with \\lambda_{eff} = [3216, 4240, 5595, 6792, 8111] Angstroms respectively. We use a maximum likelihood method which allows for a general form for the shape of the luminosity function, simple luminosity and number evolution, incorporates flux uncertainties, and accounts for the flux limits of the survey. We find luminosity densities at z=0.1 in absolute AB magnitudes in a Mpc^3 of [-14.10 \\pm 0.15, -15.18 \\pm 0.03, -15.90 \\pm 0.03, -16.24 \\pm 0.03, -16.56 \\pm 0.02] in [{0.1}{u}, {0.1}{g}, {0.1}{r}, {0.1}{i}, {0.1}{z}], respectively, using \\Omega_0 =0.3, \\Omega_\\Lambda=0.7, and h=1, and using Petrosian magnitudes. Similar results are obtained using Sersic model magnitudes, suggesting tha...

Blanton, M R; Brinkmann, J; Connolly, A J; Csabai, I; Bahcall, Neta A; Fukugita, M; Loveday, J; Meiksin, A; Munn, J A; Nichol, R C; Okamura, S; Quinn, T; Schneider, D P; Shimasaku, K; Strauss, M A; Tegmark, M; Vogeley, M S; Weinberg, D H; Blanton, Michael R.; Hogg, David W.; Connolly, Andrew J.; Csabai, Istvan; Bahcall, Neta A.; Fukugita, Masataka; Loveday, Jon; Meiksin, Avery; Munn, Jeffrey A.; Okamura, Sadanori; Quinn, Thomas; Schneider, Donald P.; Shimasaku, Kazuhiro; Strauss, Michael A.; Tegmark, Max; Vogeley, Michael S.; Weinberg, David H.

2003-01-01

168

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

International Nuclear Information System (INIS)

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 ?eff = 48.3 ± 1.9 ± 0.6 mb, which reduces the D0 contribution to the luminosity measurement uncertainty by almost 3%.

169

A New Analytic Galactic Luminosity Profile Function  

CERN Document Server

In 2010 Spergel introduced an alternative to the traditional Sersic form for galactic luminosity profiles based on modified Bessel functions of the second kind. His motivation was the desire for an accurate one-parameter profile form with a simple Fourier transform (in contrast to the Fourier transform of the Sersic profile which can't be written in closed form), but we have found that the Spergel profile almost universally makes integrals easier when it replaces the Sersic profile in the integrand. In the original paper on the subject Spergel noted that his profile seems to fit galaxies on average just as well as Sersic's. Here we make this observation quantitative by comparing the residuals from fitting Sersic and Spergel forms to data. We find that the Spergel profile actually fits better than the Sersic for a random sample of 16 galaxies.

Katz, Daniel; Lenthall, Matthew; Merousis, Alex; Sundaramurthy, Navin; Kim, Jeongki

2014-01-01

170

Unbeamed ?-rays from low luminosity AGNs  

International Nuclear Information System (INIS)

Proton-proton collisions in two-temperature accretion flows may lead to substantial ?-ray emission through neutral pion production and decay. We present preliminary results of our study of such a hadronic ?-ray emission. We find that radiatively inefficient flows around rapidly rotating black holes can produce the MeV/GeV luminosities up to ? 1044 erg s-1. The hot-flow model predictions for the hadronic and the Comptonization components can put interesting constraints on the properties of the source of high-energy radiation in AGNs. As an example, we compare our model with X/?-ray observations of Centaurus A and we find that the model with a maximally rotating black hole strongly overpredicts the ?-ray flux.

171

The radio luminosity function of cluster radio halos  

OpenAIRE

A significant fraction of galaxy clusters exhibits cluster wide radio halos. We give a simple prediction of the local and higher redshift radio halo luminosity function (RHLF) on the basis of (i) an observed and a theoretical X-ray cluster luminosity function (XCLF) (ii) the observed radio--X-ray luminosity correlation (RXLC) of galaxy clusters with radio halos (iii) an assumed fraction of 1/3 galaxy clusters to have radio halos as supported by observations. We then find 300...

Enßlin, T. A.; Ro?ttgering, H. J. A.

2002-01-01

172

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

173

The Galaxy Luminosity Function during the Reionization Epoch  

OpenAIRE

The new Wide Field Camera 3/IR observations on the Hubble Ultra-Deep Field started investigating the properties of galaxies during the reionization epoch. To interpret these observations, we present a novel approach inspired by the conditional luminosity function method. We calibrate our model to observations at z=6 and assume a non-evolving galaxy luminosity versus halo mass relation. We first compare model predictions against the luminosity function measured at z=5 and z=4...

Trenti, M.; Stiavelli, M.; Bouwens, R. J.; Oesch, P.; Shull, J. M.; Illingworth, G. D.; Bradley, L. D.; Carollo, C. M.

2010-01-01

174

The luminosity function of diverse satellite galaxy systems  

OpenAIRE

The high-resolution, SPH galaxies of the McMaster Unbiased Galaxy Survey (MUGS) are used to examine the satellite systems of sixteen model host galaxies. Each galaxy has a different mass, angular momentum and merger history that yield a rich set of satellite luminosity functions. With new observations of distant satellite systems, we can compare these luminosity functions to satellite systems beyond the Local Group. We find that the luminosity functions of our simulations co...

Nickerson, S.; Stinson, G.; Couchman, H. M. P.; Bailin, J.; Wadsley, J.

2012-01-01

175

de Sitter's model and luminosity - distance in cosmology  

International Nuclear Information System (INIS)

The behaviour of luminosity-distance with redshift is analysed within the framework of homogeneous zero-pressure relativistic cosmology. de Sitter's model is shown to have the most redshift sensitive luminosity-distance function of all cosmologies which have q0>= -1. Quasar data which suggest a cut-off in absolute luminosity are reanalysed and the cut-off disappears if either de Sitter's model or the assumption L(L?) = 3L(H?) is used. (author)

176

The Morphological Type Dependence of K-band Luminosity Functions  

OpenAIRE

Differential 2.2um (K-band) luminosity functions are presented for a complete sample of 1570 nearby Vgsr < 3000 km/s, where Vgsr is the velocity measured with respect to the Galactic standard of rest), bright (K < 10 mag), galaxies segregated by visible morphology. The K-band luminosity function for late-type spirals follows a power law that rises towards low luminosities whereas the K-band luminosity functions for ellipticals, lenticulars and bulge-dominated spirals are pea...

Devereux, Nick; Hriljac, Paul; Willner, S. P.; Ashby, M. L. N.; Willmer, C. N. A.

2009-01-01

177

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

DEFF Research Database (Denmark)

We present an updated and revised analysis of the relationship between the Hß 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 Hß time lag, which is assumed to yield the average Hß 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 BLR-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of , 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-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. © 2013. The American Astronomical Society. All rights reserved.

Bentz, M.C.; Denney, K.D.

2013-01-01

178

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 reon 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.

179

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

180

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

181

Higher luminosities via alternative incident channels  

Energy Technology Data Exchange (ETDEWEB)

We show that PEP provides some unique opportunities for one and two photon physics with real photons as well as for QCD studies with internal targets. Photon beams would avoid the major limitation on the luminosity of present machines and could provide PEP an ideal b-physics factory producing the full range of J/sub c//sup PC/ and J/sub b//sup PC/ states that may not be observable otherwise as well as allow a whole new class of ''missing-mass'' experiments. These latter particles are the pseudo-Goldstone bosons and their supersymmetric counterparts. These and related possibilities like a single-pass, ''free electron laser'' facility or even synchrotron radiation beam lines all favor a mini-maxi configuration for the low-beta insertions in PEP. This allows more diverse experiments without excluding any ongoing experimental programs. Such possibilities have interesting implications for a number of proposed facilities including the SSC. Some systematic machine physics studies over a range of energies are suggested. 24 refs., 6 figs.

Spencer, J.E.

1985-04-01

182

ATLAS gets its own luminosity detector  

CERN Multimedia

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...

CERN Bulletin

2011-01-01

183

The Luminosities of the Coldest Brown Dwarfs  

CERN Document Server

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 ...

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

2014-01-01

184

Higher luminosities via alternative incident channels  

International Nuclear Information System (INIS)

We show that PEP provides some unique opportunities for one and two photon physics with real photons as well as for QCD studies with internal targets. Photon beams would avoid the major limitation on the luminosity of present machines and could provide PEP an ideal b-physics factory producing the full range of J/sub c//sup PC/ and J/sub b//sup PC/ states that may not be observable otherwise as well as allow a whole new class of ''missing-mass'' experiments. These latter particles are the pseudo-Goldstone bosons and their supersymmetric counterparts. These and related possibilities like a single-pass, ''free electron laser'' facility or even synchrotron radiation beam lines all favor a mini-maxi configuration for the low-beta insertions in PEP. This allows more diverse experiments without excluding any ongoing experimental programs. Such possibilities have interesting implications for a number of proposed facilities including the SSC. Some systematic machine physics studies over a range of energies are suggested. 24 refs., 6 figs

185

The IR Luminosity Functions of Rich Clusters  

CERN Document Server

We present MIPS observations of the cluster A3266. About 100 spectroscopic cluster members have been detected at 24 micron. The IR luminosity function in A3266 is very similar to that in the Coma cluster down to the detection limit L_IR~10^43 ergs/s, suggesting a universal form of the bright end IR LF for local rich clusters with M~10^15 M_sun. The shape of the bright end of the A3266-Coma composite IR LF is not significantly different from that of nearby field galaxies, but the fraction of IR-bright galaxies (SFR > 0.2M_sun/yr) in both clusters increases with cluster-centric radius. The decrease of the blue galaxy fraction toward the high density cores only accounts for part of the trend; the fraction of red galaxies with moderate SFRs (0.2 < SFR < 1 M_sun/yr) also decreases with increasing galaxy density. These results suggest that for the IR bright galaxies, nearby rich clusters are distinguished from the field by a lower star-forming galaxy fraction, but not by a change in L*_IR. The composite IR LF...

Bai, Lei; Rieke, Marcia J; Christlein, Daniel; Zabludoff, Ann I

2008-01-01

186

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.

187

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 ? 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 ?-ray luminosity. Engine-driven GRBs likely have a luminosity above ?1048 erg s–1.

188

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

Energy Technology Data Exchange (ETDEWEB)

GRB 120422A is a low-luminosity gamma-ray burst (GRB) associated with a bright supernova, which distinguishes itself by its relatively short T{sub 90} ({approx}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 {approx}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 {Gamma} 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 {gamma}-ray luminosity. Engine-driven GRBs likely have a luminosity above {approx}10{sup 48} erg s{sup -1}.

Zhang Binbin; Burrows, David N. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Fan Yizhong; Wei Daming [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Shen, Rong-Feng [Department of Astronomy and Astrophysics, University of Toronto, M5S 3H4 (Canada); Xu Dong [Benoziyo Center for Astrophysics, Faculty of Physics, The Weizmann Institute of Science, Rehovot 76100 (Israel); Zhang Fuwen [College of Science, Guilin University of Technology, Guilin, Guangxi 541004 (China); Zhang Bing [Department of Physics and Astronomy, University of Nevada Las Vegas, Las Vegas, NV 89154 (United States); Gehrels, Neil, E-mail: bbzhang@psu.edu, E-mail: yzfan@pmo.ac.cn, E-mail: zhang@physics.unlv.edu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2012-09-10

189

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

CERN Document Server

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...

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

2008-01-01

190

The Metallicity-Luminosity Relation, Effective Yields, and Metal Loss in Spiral and Irregular Galaxies  

CERN Document Server

I present results on the correlation between galaxy mass, luminosity, and metallicity for a sample of spiral and irregular galaxies having well-measured abundance profiles, distances, and rotation speeds. Additional data for low surface brightness galaxies from the literature are also included for comparison. These data are combined to study the metallicity-luminosity and metallicity-rotation speed correlations for spiral and irregular galaxies. The metallicity luminosity correlation shows its familiar form for these galaxies, a roughly uniform change in the average present-day O/H abundance of about a factor 100 over 11 magnitudes in B luminosity. However, the O/H - V(rot) relation shows a change in slope at a rotation speed of about 125 km/sec. At faster V(rot), there appears to be no relation between average metallicity and rotation speed. At lower V(rot), the metallicity correlates with rotation speed. This change in behavior could be the result of increasing loss of metals from the smaller galaxies in su...

Garnett, D R

2002-01-01

191

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

192

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

Science.gov (United States)

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).

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

193

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, ?W, ?Z, ??, 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

194

Measuring luminosity at LHCb using elastic diphoton dimuon production  

CERN Document Server

We report on an indirect method being used to measure luminosity at LHCb. It involves recording the event rate of elastic diphoton dimuon production. Preliminary MC studies suggest that with 1 fb^{-1} of data this method could provide a luminosity measurement with a precision of better than 2%

Moran, Dermot

2011-01-01

195

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

CERN Document Server

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. Combined with the halo mass function, this description reproduces the observed characteristics of the galaxy LF, including a shape consistent with the Schechter function. When all galaxies are included, regardless of the environment or the Hubble type, the Schechter L* is the luminosity scale above which the central galaxy luminosity-halo mass relation flattens; L* corresponds to ~10^{13}Msun on the halo mass scale. In surveys where central galaxies in massive clusters are neglected, either by design or because of the cosmic...

Cooray, A R; Cooray, Asantha; Milosavljevic, Milos

2005-01-01

196

ISOTROPIC LUMINOSITY INDICATORS IN A COMPLETE AGN SAMPLE  

International Nuclear Information System (INIS)

The [O IV] ?25.89 ?m line has been shown to be an accurate indicator of active galactic nucleus (AGN) intrinsic luminosity in that it correlates well with hard (10-200 keV) X-ray emission. We present measurements of [O IV] for 89 Seyfert galaxies from the unbiased revised Shapley-Ames (RSA) sample. The [O IV] luminosity distributions of obscured and unobscured Seyferts are indistinguishable, indicating that their intrinsic AGN luminosities are quite similar and that the RSA sample is well suited for tests of the unified model. In addition, we analyze several commonly used proxies for AGN luminosity, including [O III] ?5007 A, 6 cm radio, and 2-10 keV X-ray emission. We find that the radio luminosity distributions of obscured and unobscured AGNs show no significant difference, indicating that radio luminosity is a useful isotropic luminosity indicator. However, the observed [O III] and 2-10 keV luminosities are systematically smaller for obscured Seyferts, indicating that they are not emitted isotropically.

197

Observations of low-luminosity radio galaxies at 102 MHz  

International Nuclear Information System (INIS)

This paper presents results given of the observations of 38 low-luminosity radio galaxies at 102 MHz by the method of interplanetary scintillation. The authors give a detailed analysis of the observational data for the objects. Low-luminosity radio galaxies with upper limits of the flux densities at 102 MHz are shown

198

ATLAS Future Plans: Upgrade and the Physics with High Luminosity  

CERN Document Server

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.

Rajagopalan, Srini; The ATLAS collaboration

2012-01-01

199

Luminosity and Beam Spot Determination Using the ATLAS Detector  

CERN Document Server

We present the algorithms and results of the reconstruction of the luminous region (also known as beam spot) and measurement of the luminosity in the ATLAS experiment during the first LHC run at energies between sqrt(s) = 900 GeV (in 2009) and sqrt(s) = 7 TeV (in 2010). The LHC luminosity is determined in real time approximately once per second using a number of detectors and algorithms, each having different acceptances, systematic uncertainties and sensitivity to background. These results are displayed in the ATLAS control room and archived every two minutes; a single "preferred" measurement is reported to the LHC. During offline analysis, additional luminosity algorithms are studied and are compared to online results to further constrain systematic uncertainties on the measurement. Relative luminosities between detectors and methods agree to within a few per cent. Determination of the absolute luminosity using Monte Carlo calibrations is limited by a ~20% systematic uncertainty from the modeling of diffrac...

Miller, D W; The ATLAS collaboration

2010-01-01

200

Luminosity for electron-positron collision in TRISTAN  

International Nuclear Information System (INIS)

Preliminary considerations on the luminosity for electron-positron collision in the TRISTAN electron ring are presented. It is shown that luminosity of 1032 cm-2s-1 can be achieved at 15 GeV with a beam current of 100 mA (each beam) and an RF power of 3.2 -- 4.1 MW (each beam). In the lower energy region, the luminosity is tune-shift limited and decreases as E2. In the higher energy region, the luminosity is RF power limited and decreases as 1/E3 or faster. The energy region above 5 GeV can be used for physics experiments with a luminosity over 1031 cm-2s-1. The maximum operating energy should be determined by the detailed investigation on the properties of the RF system. (auth.)

201

A Comparison of [OIII] and Mid-Infrared Luminosity Indicators In Optically-Selected Type I and Type II Quasars  

Science.gov (United States)

Quasars, the most luminous active galactic nuclei, are excellent probes for relating the growth of supermassive black holes to galaxy evolution. Quasars are often separated into Type I, or unobscured quasars and Type II, or obscured quasars, and the difference is often attributed to dust obscuration along our line of sight. To compare samples of quasars in an unbiased way, it is vital to estimate accurate quasar luminosities. Here, we compare the luminosities for two samples of optically-selected Type I and Type II quasars derived using two common indicators: [OIII]5007 emission-line flux and mid-IR continuum emission. While we observe a trend between the two indicators across two orders of magnitude, we find that at a given [OIII] luminosity, Type I quasars have a larger mid-IR luminosity than Type II quasars by a factor of 2-3. We explore this difference using SED template fitting to estimate the effects of dust obscuration on the mid-IR continuum, and find that our dust-corrected mid IR luminosities are similar for Type I and Type II quasars. These results indicate the importance in accounting for obscuration of mid-IR flux by cool dust in Type II quasars to properly estimate mid-IR luminosities.

Hainline, Kevin N.; Hickox, Ryan C.; Carroll, Christopher M.

2015-01-01

202

Simulation of the LHC BRAN luminosity monitor for high luminosity interaction regions  

Energy Technology Data Exchange (ETDEWEB)

The BRAN (Beam RAte of Neutrals) detector monitors the collision rates in the high luminosity interaction regions of LHC (ATLAS and CMS). This Argon gas ionization detector measures the forward neutral particles from collisions at the interaction point. To predict and improve the understanding of the detector's performance, we produced a detailed model of the detector and its surroundings in Fluka. In this paper, we present the model and results of our simulations including the detectors estimated response to interactions for beam energies of 3.5, 5, and 7 TeV.

Miyamoto, R.; Matis, H.; Ratti, A.; Stiller, J.; White, S.M.

2010-05-23

203

Evolution of Galaxy Luminosity Function Using Photometric Redshifts  

CERN Document Server

We examine the impact of using photometric redshifts for studying the evolution of both the global galaxy luminosity function (LF) and that for different galaxy types. To this end we compare LFs obtained using photometric redshifts from the CFHT Legacy Survey (CFHTLS) D1 field with those from the spectroscopic survey VIMOS VLT Deep Survey (VVDS) comprising ~4800 galaxies. We find that for z<2, in the interval of magnitudes considered by this survey, the LFs obtained using photometric and spectroscopic redshifts show a remarkable agreement. This good agreement led us to use all four Deep fields of CFHTLS comprising ~386000 galaxies to compute the LF of the combined fields and estimate directly the error in the parameters based on field-to-field variation. We find that the characteristic absolute magnitude M* of Schechter fits fades by ~0.7mag from z~1.8 to z~0.3, while the characteristic density phi* increases by a factor of ~4 in the same redshift bin. We use the galaxy classification provided by the templ...

Ramos, B H F; Benoist, C; da Costa, L N; Maia, M A G; Makler, M; Ogando, R L C; de Simoni, F; Mesquita, A A

2011-01-01

204

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 s–1 in both old field populations and GCs.

205

Galactic Ultracompact X-ray Binaries: Empirical Luminosities  

CERN Document Server

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 PCA 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 X-ray luminosity functions in other galaxies cannot be explained by an increased fraction of UCXBs in globular clusters. Instead, our measured luminosity function suggests that UCXBs only make up a small fraction of the X-ray binaries above a few times 10^36 ergs/s in both old field p...

Cartwright, T F; Heinke, C O; Sivakoff, G R; Berger, J J; Gladstone, J C; Ivanova, N

2013-01-01

206

GALACTIC ULTRACOMPACT X-RAY BINARIES: EMPIRICAL LUMINOSITIES  

Energy Technology Data Exchange (ETDEWEB)

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 Multiplication-Sign 10{sup 36} erg s{sup -1} in both old field populations and GCs.

Cartwright, T. F.; Engel, M. C.; Heinke, C. O.; Sivakoff, G. R.; Berger, J. J.; Gladstone, J. C.; Ivanova, N., E-mail: heinke@ualberta.ca [Physics Department, 4-183 CCIS, University of Alberta, Edmonton, AB T6G 2E1 (Canada)

2013-05-10

207

Precision luminosity measurement with the OPAL silicon-tungsten calorimeters  

CERN Document Server

A preliminary, high precision measurement of the luminosity of the LEP colliding beams for the LEP I data recorded between 1993 and 1995 with the OPAL experiment is presented, the measurement is based on the OPAL Silicon-Tungten luminosity monitor, which detects electrons from small-angle Bhabha scattering at angles between approximately 25 and 58 mrad. The overall experimental uncertainty on the measured luminosity is 3.3*10/sup -4/. Such uncertainty contributes negligibly to the uncertainty on the OPAL cross section measurements near the Z /sup 0/ resonance. (3 refs).

Arcelli, S

1999-01-01

208

Change to the D0 luminosity monitor constant  

International Nuclear Information System (INIS)

The D0 experiment has previously calculated its luminosities using a visible cross section (luminosity monitor constant) for its Level 0 trigger, ?L0 = 42.9 mb based on the E710 inelastic cross section measurements. Recently, CDF has also published inelastic cross section measurements markedly different from E710. The D0 experiment has moved to world average inelastic cross sections at ?s = 1.8 TeV. The result changes the D0 visible cross section to ?L0 = 48.2 mb which is an increase of 12.4% in the visible cross section value. The error on luminosity has been left unchanged at 12%

209

Deriving an X-ray luminosity function of dwarf novae  

International Nuclear Information System (INIS)

Current measurements of X-ray luminosity functions of dwarf novae contain biases due to high X-ray flux sources. We have obtained Suzaku, XMM-Newton and ASCA observations of nearby DNe which have parallax-based distance measurements, and carried out X-ray spectral analysis for these sources. Our primary goal is to derive a reliable X-ray luminosity function for this sample, and to compare it with existing X-ray luminosity functions. We briefly introduce the source sample and preliminary results.

210

Computation of the TEVATRON luminosity using measured machine parameters  

International Nuclear Information System (INIS)

In order to extract the cross section from a measured reaction rate an experimenter needs to know the incident flux. At a collider the flux is referred to as the luminosity L. The luminosity can be determined in an experiment by measuring the rate of a reaction with a known cross section. This paper describes an alternative calculation of the luminosity based on measurements made on the stored beam in the TEVATRON. The measurements necessary for the calculation, which must be made on each of the p and bar p bunches, are the intensity and the transverse and longitudinal extent of each of the bunches

211

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

212

Line excess in low-luminosity young stellar objects  

International Nuclear Information System (INIS)

Infrared spectra of 13 low-luminosity young stellar objects (YSOs) indicate that a majority have excess hydrogen line emission. This is in contradiction to a simple model of excess recombination line emission due to ionization from the first excited level of hydrogen. Thermal neutral atomic emission models do not violate energy conservation but require a few percent of the total luminosity utilized in heating an extended emission region. Whether there is a similar line excess emission mechanism for low- and high-luminosity YSOs is still open to question. 21 references

213

The Luminosities of Protostars in the Spitzer c2d and Gould Belt Legacy Clouds  

CERN Document Server

Motivated by the long-standing "luminosity problem" in low-mass star formation whereby protostars are underluminous compared to theoretical expectations, we identify 230 protostars in 18 molecular clouds observed by two Spitzer Space Telescope Legacy surveys of nearby star-forming regions. We compile complete spectral energy distributions, calculate Lbol for each source, and study the protostellar luminosity distribution. This distribution extends over three orders of magnitude, from 0.01 Lsun - 69 Lsun, and has a mean and median of 4.3 Lsun and 1.3 Lsun, respectively. The distributions are very similar for Class 0 and Class I sources except for an excess of low luminosity (Lbol < 0.5 Lsun) Class I sources compared to Class 0. 100 out of the 230 protostars (43%) lack any available data in the far-infrared and submillimeter (70 um < wavelength < 850 um) and have Lbol underestimated by factors of 2.5 on average, and up to factors of 8-10 in extreme cases. Correcting these underestimates for each source...

Dunham, Michael M; Allen, Lori E; Evans, Neal J; Broekhoven-Fiene, Hannah; Chapman, Nicholas L; Cieza, Lucas A; Gutermuth, Robert A; Harvey, Paul M; Hatchell, Jennifer; Huard, Tracy L; Kirk, Jason M; Matthews, Brenda C; Merin, Bruno; Miller, Jennifer F; Peterson, Dawn E; Spezzi, Loredana

2013-01-01

214

A novel method for an absolute luminosity measurement at LHCb with beam-gas imaging  

International Nuclear Information System (INIS)

A novel technique to measure the absolute luminosity at the Large Hadron Collider (LHC) using beam-gas interactions has been successfully used in the LHCb experiment. A gas injection device (SMOG) has been installed in the LHCb experiment to increase the pressure around the interaction point during dedicated fills. The Beam-Gas Imaging method (BGI) has now the potential to surpass the accuracy of the commonly used *van der Meer scan* method (VDM). The technique has been used in 10 LHC fills during 2012 including and also provided a first luminosity measurement for proton-lead collisions. This talk presents the principles of the gas injection and the improvements reached with the increased pressure. Furthermore the gas injection increased the accuracy measurement of the so-called ghost charges and also intensities per bunch. Those uncertainties are becoming the dominating factor because the uncertainty on the total beam current have been reduced.

215

Higgs boson mass and high-luminosity LHC probes of supersymmetry with vectorlike top quark  

CERN Document Server

We consider an extension of the MSSM with an added vectorlike top partner. Our aim is to revisit to what extent such an extension can raise the Higgs boson mass through radiative corrections and help ameliorate the MSSM hierarchy problem, and to specify what experimental probes at the LHC will find or exclude this possibility during the high-luminosity phase. Direct detection, precision electroweak and precision Higgs analyses are all commissioned to this end. To achieve the $ 125 \\, \\textrm{GeV} \\ $ Higgs boson mass, we find that superpartner masses can be reduced by a factor of more than three in this scenario compared to the MSSM without the extra vectorlike top quark, and that during the high-luminosity phase of the LHC precision Higgs analysis is expected to become the most powerful experimental probe of the scenario.

Lalak, Zygmunt; Wells, James D

2015-01-01

216

A novel method for an absolute luminosity measurement at LHCb with beam-gas imaging  

Energy Technology Data Exchange (ETDEWEB)

A novel technique to measure the absolute luminosity at the Large Hadron Collider (LHC) using beam-gas interactions has been successfully used in the LHCb experiment. A gas injection device (SMOG) has been installed in the LHCb experiment to increase the pressure around the interaction point during dedicated fills. The Beam-Gas Imaging method (BGI) has now the potential to surpass the accuracy of the commonly used *van der Meer scan* method (VDM). The technique has been used in 10 LHC fills during 2012 including and also provided a first luminosity measurement for proton-lead collisions. This talk presents the principles of the gas injection and the improvements reached with the increased pressure. Furthermore the gas injection increased the accuracy measurement of the so-called ghost charges and also intensities per bunch. Those uncertainties are becoming the dominating factor because the uncertainty on the total beam current have been reduced.

Barschel, Colin [RWTH Aachen, III. Physikalisches Institut A (Germany)

2013-07-01

217

Gas dynamics in high-luminosity polarized He-3 targets using diffusion and convection  

CERN Document Server

The dynamics of the movement of gas is discussed for two-chambered polarized He-3 target cells of the sort that have been used successfully for many electron scattering experiments. A detailed analysis is presented showing that diffusion presents a limiting factor in target performance, particularly as these targets are run at increasingly high luminosities. Measurements are presented on a new prototype polarized He-3 target cell in which the movement of gas is due largely to convection instead of diffusion. NMR tagging techniques have been used to visualize the gas flow, showing velocities along a cylindrically-shaped target of between 5-80 cm/min. The new target design addresses one of the principle obstacles to running polarized He-3 targets at substantially higher luminosities while simultaneously providing new flexibility in target geometry.

Dolph, P A M; Averett, T; Kelleher, A; Mooney, K E; Nelyubin, V; Tobias, W A; Wojsekhowski, B; Cates, G D

2011-01-01

218

THE LUMINOSITIES OF PROTOSTARS IN THE SPITZER c2d AND GOULD BELT LEGACY CLOUDS  

Energy Technology Data Exchange (ETDEWEB)

Motivated by the long-standing 'luminosity problem' in low-mass star formation whereby protostars are underluminous compared to theoretical expectations, we identify 230 protostars in 18 molecular clouds observed by two Spitzer Space Telescope Legacy surveys of nearby star-forming regions. We compile complete spectral energy distributions, calculate L{sub bol} for each source, and study the protostellar luminosity distribution. This distribution extends over three orders of magnitude, from 0.01 L{sub Sun} to 69 L{sub Sun }, and has a mean and median of 4.3 L{sub Sun} and 1.3 L{sub Sun }, respectively. The distributions are very similar for Class 0 and Class I sources except for an excess of low luminosity (L{sub bol} {approx}< 0.5 L{sub Sun }) Class I sources compared to Class 0. 100 out of the 230 protostars (43%) lack any available data in the far-infrared and submillimeter (70 {mu}m <{lambda} < 850 {mu}m) and have L{sub bol} underestimated by factors of 2.5 on average, and up to factors of 8-10 in extreme cases. Correcting these underestimates for each source individually once additional data becomes available will likely increase both the mean and median of the sample by 35%-40%. We discuss and compare our results to several recent theoretical studies of protostellar luminosities and show that our new results do not invalidate the conclusions of any of these studies. As these studies demonstrate that there is more than one plausible accretion scenario that can match observations, future attention is clearly needed. The better statistics provided by our increased data set should aid such future work.

Dunham, Michael M.; Arce, Hector G. [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520 (United States); Allen, Lori E. [National Optical Astronomy Observatories, Tucson, AZ (United States); Evans II, Neal J.; Harvey, Paul M. [Department of Astronomy, University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, TX 78712-1205 (United States); Broekhoven-Fiene, Hannah; Matthews, Brenda C. [Herzberg Institute, National Research Council of Canada, 5071 W. Saanich Road, Victoria, BC V9E 2E7 (Canada); Chapman, Nicholas L. [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), Department of Physics and Astronomy, 2145 Sheridan Road, Evanston, IL 60208 (United States); Cieza, Lucas A. [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); Gutermuth, Robert A. [Department of Astronomy, University of Massachusetts, Amherst, MA (United States); Hatchell, Jennifer [Astrophysics Group, Physics, University of Exeter, Exeter EX4 4QL (United Kingdom); Huard, Tracy L.; Miller, Jennifer F. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Kirk, Jason M. [School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff CF24 3AA (United Kingdom); Merin, Bruno [Herschel Science Centre, ESAC-ESA, P.O. Box 78, E-28691 Villanueva de la Canada, Madrid (Spain); Peterson, Dawn E. [Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301 (United States); Spezzi, Loredana, E-mail: michael.dunham@yale.edu [European Southern Observatory (ESO), Karl-Schwarzschild-Strasse 2, D-85748 Garching bei Muenchen (Germany)

2013-04-15

219

The Kinematics of the Lag-Luminosity Relationship  

Energy Technology Data Exchange (ETDEWEB)

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.

Salmonson, J D

2004-03-17

220

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, ?L0 = 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, ?L0 = 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

221

Estimating the Prompt Electromagnetic Luminosity of a Black Hole Merger  

CERN Document Server

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 gravitati...

Krolik, Julian H

2009-01-01

222

The Intrinsic Quasar Luminosity Function: Accounting for Accretion Disk Anisotropy  

CERN Document Server

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 l...

DiPompeo, M A; Brotherton, M S; Runnoe, J C; Green, R F

2014-01-01

223

Galaxy morphology, luminosity and environment in the SDSS DR7  

CERN Document Server

We study the influence of the environment on the evolution of galaxies by investigating the luminosity function (LF) of galaxies of different morphological types at different environmental density levels. We construct the LFs separately for spiral and elliptical galaxies using data from the Sloan Digital Sky Survey (SDSS), correcting the luminosities for the intrinsic absorption. We use the global luminosity density field to define different environments. The smoothed bootstrap method is used to calculate confidence regions of the derived luminosity functions. We find a strong environmental dependency for the LF of elliptical galaxies. The LF of spiral galaxies is almost environment independent, suggesting that spiral galaxy formation mechanisms are similar in different environments. Absorption by the intrinsic dust influences the bright-end of the LF of spiral galaxies. After attenuation correction, the brightest spiral galaxies are still about 0.5 mag less luminous than the brightest elliptical galaxies. De...

Tempel, E; Liivamägi, L J; Tamm, A; Einasto, J; Einasto, M; Müller, V

2010-01-01

224

Collider physics at high energies and low luminosities  

Science.gov (United States)

While very high acceleration gradients are expected in novel accelerating schemes such as those discussed by IZEST, generating high luminosities will be extremely challenging and will likely require a separate technology revolution. It is important to determine if a low-luminosity but high energy collider would have serious interest from a particle physics perspective. We consider a process involving physics beyond the Standard Model that would be detectable at high energies without requiring the types of luminosities normally quoted for future colliders, "classicalization". In this example, scattering cross sections grow with a power of the center-of-mass energy, thereby reducing the luminosity requirement at high energies. Another process discussed is deep-inelastic-scattering of electrons on protons, where a precision measurement of the energy dependence of the scattering cross section could yield information about physics processes at much higher scales.

Caldwell, A.

2014-05-01

225

Collider physics at high energies and low luminosities  

International Nuclear Information System (INIS)

While very high acceleration gradients are expected in novel accelerating schemes such as those discussed by IZEST, generating high luminosities will be extremely challenging and will likely require a separate technology revolution. It is important to determine if a low-luminosity but high energy collider would have serious interest from a particle physics perspective. We consider a process involving physics beyond the Standard Model that would be detectable at high energies without requiring the types of luminosities normally quoted for future colliders. In this example, scattering cross sections grow with a power of the center-of-mass energy, thereby reducing the luminosity requirement at high energies. Another process discussed is deep-inelastic-scattering of electrons on protons, where a precision measurement of the energy dependence of the scattering cross section could yield information about physics processes at much higher scales. (author)

226

The Luminosity Function of the Milky Way Satellites  

OpenAIRE

We quantify the detectability of stellar Milky Way satellites in the Sloan Digital Sky Survey (SDSS) Data Release 5. We show that the effective search volumes for the recently discovered SDSS--satellites depend strongly on their luminosity, with their maximum distance, $D_{max}$, substantially smaller than the Milky Way halo's virial radius. Calculating the maximum accessible volume, $V_{max}$, for all faint detected satellites, allows the calculation of the luminosity funct...

Koposov, S.; Belokurov, V.; Evans, N. W.; Hewett, P. C.; Irwin, M. J.; Gilmore, G.; Zucker, D. B.; Rix, H. -w; Fellhauer, M.; Bell, E. F.; Glushkova, E. V.

2007-01-01

227

Physics at a High-Luminosity LHC with ATLAS  

OpenAIRE

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...

Atlas, The Collaboration; Desy, Forschung Hochenergiephysik

2013-01-01

228

The luminosity function of Swift long gamma-ray bursts  

OpenAIRE

The accumulation of {\\it Swift} observed gamma-ray bursts (GRBs) gradually makes it possible to directly derive a GRB luminosity function (LF) from observational luminosity distribution, where however two complexities must be involved as (i) the evolving connection between GRB rate and cosmic star formation rate and (ii) observational selection effects due to telescope thresholds and redshift measurements. With a phenomenological investigation on these two complexities, we c...

Cheng, Ks; Zheng, Xp; Cao, Xf; Yu, Yw

2011-01-01

229

The Planetary Nebula Luminosity Function at the Dawn of Gaia  

OpenAIRE

The [O III] 5007 Planetary Nebula Luminosity Function (PNLF) is an excellent extragalactic standard candle. In theory, the PNLF method should not work at all, since the luminosities of the brightest planetary nebulae (PNe) should be highly sensitive to the age of their host stellar population. Yet the method appears robust, as it consistently produces < 10% distances to galaxies of all Hubble types, from the earliest ellipticals to the latest-type spirals and irregulars. It ...

Ciardullo, Robin

2012-01-01

230

A bimodal model for the galaxy luminosity function  

Science.gov (United States)

The galaxy luminosity function in the Virgo cluster has been recently found to show a clear separation between bright galaxies and dwarf galaxies. Here, consideration is given to the effect on the luminosity function of galaxy binding energy which allows gas to be retained and star formation to proceed over about 1 Gyr in massive galaxies, but implies wind-driven mass loss and inefficient star formation in dwarf galaxies.

Schaeffer, R.; Silk, J.

1988-01-01

231

Experience with high luminosity running at the CERN ISR  

International Nuclear Information System (INIS)

Discussed is the experience of the CCOR and COR collaborations at the ISR at the steel low ? intersection region, with luminosities up to 6 x 1031 cm-2s-1. In general, this luminosity level has caused only minor inconvenience for a detector covering polar angles 45 to 135 degrees in the center of mass, except for a special unrestrictive trigger on total transverse energy

232

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.

233

Toward a galaxian luminosity-metallicity relation spanning ten magnitudes  

OpenAIRE

We describe the two projects by which we are assembling a database of near-IR luminosities and direct oxygen abundances for both high- and low-mass star-forming galaxies in the nearby Universe. This will eventually allow us to construct the first reliable and homogeneous luminosity-metallicity relation, to be compared to theoretical models of galactic evolution, and to the relations for galaxies at higher redshifts.

Saviane, Ivo; Bresolin, Fabio; Salzer, John

2007-01-01

234

On the Luminosity Distance and the Hubble Constant  

Directory of Open Access Journals (Sweden)

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.

Yuri Heymann

2013-07-01

235

Summary Of Working Group On Single Beam High Luminosity Issues  

CERN Document Server

The aim of the Working Group on Single Beam Behaviour was to concentrate on the items limiting the achievement of high luminosity. Some are related to high current and short bunch distance, as electron cloud instability (ECI), the others to the lattice design, as Dynamic Aperture (DA), wigglers, Interaction Region (IR) design, lifetime and background. These arguments have been discussed to explore the feasibility of a very high luminosity Phi-factory.

Guiducci, S

2004-01-01

236

The Morphology Dependence of Luminosity Segregation in the Coma Cluster  

CERN Document Server

We carry out CCD photometry of galaxies in the 5.25 square region centered on Coma cluster down to $M_R=-16.0$, beyond the limit of conventional morphological classification. We use the angular two-point correlation function as well as radial profiles in order to characterize the luminosity segregation. We find strong luminosity segregation for our total sample over the magnitude range of $-20 \\leq M_R \\leq -16$, which is not entirely accounted for in terms of the morphology-density relation that is known to exist only for bright galaxies. We use a single consistent parameter, the degree of luminosity concentration, to parameterize the morphology of galaxies over the wide magnitude range, where both giant and dwarf galaxies are included. Galaxies with high central concentration (HCC) show strong luminosity segregation, i.e. their clustering strength depends strongly on luminosity while those with low central concentration (LCC) show almost no luminosity segregation. Radial density profile shows that brighter ...

Kashikawa, N; Doi, M; Komiyama, Yu; Okamura, S; Shimasaku, K; Yagi, M; Yasuda, N

1998-01-01

237

Luminosity function and jet structure of Gamma-Ray Burst  

Science.gov (United States)

The structure of gamma-ray burst (GRB) jets impacts on their prompt and afterglow emission properties. The jet of GRBs could be uniform, with constant energy per unit solid angle within the jet aperture, or it could be structured, namely with energy and velocity that depend on the angular distance from the axis of the jet. We try to get some insight about the still unknown structure of GRBs by studying their luminosity function. We show that low (1046-48 erg s-1) and high (i.e. with L ? 1050 erg s-1) luminosity GRBs can be described by a unique luminosity function, which is also consistent with current lower limits in the intermediate luminosity range (1048-50 erg s-1). We derive analytical expressions for the luminosity function of GRBs in uniform and structured jet models and compare them with the data. Uniform jets can reproduce the entire luminosity function with reasonable values of the free parameters. A structured jet can also fit adequately the current data, provided that the energy within the jet is relatively strongly structured, i.e. E ? ?-k with k ? 4. The classical E ? ?-2 structured jet model is excluded by the current data.

Pescalli, A.; Ghirlanda, G.; Salafia, O. S.; Ghisellini, G.; Nappo, F.; Salvaterra, R.

2015-02-01

238

The luminosity function of diverse satellite galaxy systems  

CERN Document Server

The high-resolution, SPH galaxies of the McMaster Unbiased Galaxy Survey (MUGS) are used to examine the satellite systems of sixteen model host galaxies. Each galaxy has a different mass, angular momentum and merger history that yield a rich set of satellite luminosity functions. With new observations of distant satellite systems, we can compare these luminosity functions to satellite systems beyond the Local Group. We find that the luminosity functions of our simulations compare well to observations when the luminosity functions are scaled according to host mass. We use the recently-found relationship between dwarf satellites and host mass in distant satellite systems (Trentham & Tully 2009) to normalize a theoretical, complete luminosity function for the Milky Way (Koposov et al. 2008). The luminosity function of satellites, expressed as a function of the host mass, is given by dN/dM_V= 3.5 x M_host^(0.91) x 10^(0.1 x M_V-10.2), where host mass is given in M_sun. The mass of a host galaxy can be used to...

Nickerson, S; Couchman, H M P; Bailin, J; Wadsley, J

2012-01-01

239

The local radio luminosity function of galaxies at 843 MHz  

International Nuclear Information System (INIS)

Following a previous investigation of the radio luminosity function, two samples of galaxies have been observed with the Molonglo Observatory Synthesis Telescope at 843 MHz. These comprise 176 E and SO galaxies, and 21 galaxies with delta 0. The resulting local radio luminosity function (LRLF) has been extended to radio powers of approx. 1018 WHz-1 sr-1. At such low luminosities, the irregular galaxies apparently begin to dominate the LRLF. Spirals on the other hand, continue to be confined to radio powers in the range 10sup(19-22) W Hz-1 sr-1. E and SO galaxies appear unimportant to the LRLF at low radio luminosities but behave like similar standard candles above powers of approx. 10sub(22.5) WHz-1 sr-1. The most massive SO galaxies appear similar to radio ellipticals, but at lower optical luminosities comparable to those of spirals. In addition SO galaxies resemble early-type spirals closely both in their detection rate and correlation between radio and optical luminosities. (author)

240

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

CERN Document Server

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...

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

241

The Radius-Luminosity Relationship for Active Galactic Nuclei : The Effect of Host-Galaxy Starlight on Luminosity Measurements  

DEFF Research Database (Denmark)

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 host-galaxy starlight contribution to the continuum luminosity at 5100 A through the typical ground-based slit position and geometry used in the reverberation-mapping campaigns. We find that removing the starlight contribution results in a significant correction to the luminosity of each AGN, both for lower luminosity sources, as expected, but also for the higher luminosity sources such as the PG quasars. After accounting for the host galaxy starlight, we revisit the well-known broad-line region radius--luminosity relationship for nearby AGN. We find the power-law slope of the relationship for the H beta line to be 0.518 +/- 0.039, shallower than previously reported and consistent with the slope of 0.5 expected fromthe naive theoretical assumption that all AGN have, on average, the same ionizing spectrum and the same ionization parameter and gas density in the H beta line-emitting region.

Bentz, Misty C.; Peterson, Bradley M.

2006-01-01

242

The Luminosity Function at z ~ 8 from 97 Y-band Dropouts: Inferences about Reionization  

Science.gov (United States)

We present the largest search to date for Y-band dropout galaxies (z ~ 8 Lyman break galaxies, LBGs) based on 350 arcmin2 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 arcmin2 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 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^\\star = -20.15^{+0.29}_{-0.38}, a faint-end slope of \\alpha = -1.87^{+0.26}_{-0.26}, and a number density of log _{10} \\phi ^\\star [{Mpc}^{-3}] = -3.24^{+0.25}_{-0.24}. Integrated down to M = -17.7, this luminosity function yields a luminosity density log _{10} \\epsilon [erg\\, s^{-1\\, Hz^{-1}\\, Mpc^{-3}}] = 25.52^{+0.05}_{-0.05}. Our luminosity function analysis is consistent with previously published determinations within 1?. 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.

Schmidt, Kasper B.; Treu, Tommaso; Trenti, Michele; Bradley, Larry D.; Kelly, Brandon C.; Oesch, Pascal A.; Holwerda, Benne W.; Shull, J. Michael; Stiavelli, Massimo

2014-05-01

243

A luminosity measurement at LEP using the L3 detector  

Energy Technology Data Exchange (ETDEWEB)

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.).

Koffeman, E.N.

1996-06-25

244

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.)

245

The critical accretion luminosity for magnetized neutron stars  

Science.gov (United States)

The accretion flow around X-ray pulsars with a strong magnetic field is funnelled by the field to relatively small regions close to the magnetic poles of the neutron star (NS), the hotspots. During strong outbursts regularly observed from some X-ray pulsars, the X-ray luminosity can be so high that the emerging radiation is able to stop the accreting matter above the surface via radiation-dominated shock, and the accretion column begins to rise. This border luminosity is usually called the `critical luminosity'. Here we calculate the critical luminosity as a function of the NS magnetic field strength B using the exact Compton scattering cross-section in a strong magnetic field. Influence of the resonant scattering and photon polarization is taken into account for the first time. We show that the critical luminosity is not a monotonic function of the B-field. It reaches a minimum of a few 1036 erg s-1 when the cyclotron energy is about 10 keV and a considerable amount of photons from a hotspot have energy close to the cyclotron resonance. For small B, this luminosity is about 1037 erg s-1, nearly independent of the parameters. It grows for the B-field in excess of 1012 G because of the drop in the effective cross-section of interaction below the cyclotron energy. We investigate how different types of the accretion flow and geometries of the accretion channel affect the results and demonstrate that the general behaviour of the critical luminosity on the B-field is very robust. The obtained results are shown to be in good agreement with the available observational data and provide a necessary ground for the interpretation of upcoming high-quality data from the currently operating and planned X-ray telescopes.

Mushtukov, Alexander A.; Suleimanov, Valery F.; Tsygankov, Sergey S.; Poutanen, Juri

2015-02-01

246

On the Radio and Optical Luminosity Evolution of Quasars  

Energy Technology Data Exchange (ETDEWEB)

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.

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

247

The GOODS-MUSIC Sample: Evolution of the Luminosity Function of Red and Blue Galaxies  

Science.gov (United States)

Using data from the GOODS public survey we analysed the galaxy properties in terms of the colour and specific star formation rate (SSFR) distributions. More specifically we analysed the galaxy bimodal distribution up to relatively high redshift (z ?q 3). We used these properties to separate the galaxy sample in two populations (red-blue using colour; early-late using SSFR). We have then studied the evolution of the red/early and blue/late luminosity function (LF) and of the luminosity density. For the blue galaxies we find a luminosity evolution with a brightening of M^* in the z=0.2-1 interval and at higher redshift a constant LF. For the red sample, we find at the bright-end of the LF a constant density in the range 0.2-0.67 and a density reduction by a factor 5 up to redshift 3.5. For the red population we also find a characteristic shape for the LF, with a minimum around M_B(AB)=-18 and with a turn up at fainter magnitude. This shape has been represented by a double Schechter function.

Salimbeni, S.; Giallongo, E.; Grazian, A.

2007-12-01

248

The Dependence of Type Ia Supernova Luminosities on their Host Galaxies  

CERN Document Server

(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...

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

249

Mid-infrared properties of nearby low-luminosity AGN at high angular resolution  

CERN Document Server

High spatial resolution mid-infrared (MIR) 12 \\mum continuum imaging of low-luminosity active galactic nuclei (LLAGN) obtained by VLT/VISIR is presented. The goal of this investigation is to determine if the nuclear MIR emission of LLAGN is consistent with the existence of a dusty obscuring torus. A sample of 17 nearby LLAGN was selected and combined with archival VISIR data of 9 additional LLAGN with available X-ray measurements. Of the 17 observed LLAGN, 7 are detected, while upper limits are derived for the 10 non-detections. All detections except NGC 3125 appear point-like on a spatial scale of \\sim 0.35". The detections do not significantly deviate from the known MIR-X-ray correlation but extend it by a factor of \\sim 10 down to luminosities < 10^41 erg/s with a narrow scatter. The latter is dominated by the uncertainties in the X-ray luminosity. Interestingly, a similar correlation with comparable slope but with a normalization differing by \\sim 2.6 orders of magnitude has been found for local starbu...

Asmus, D; Smette, A; Hönig, S F; Duschl, W J

2011-01-01

250

Low-luminosity X-ray sources and the Galactic ridge X-ray emission  

CERN Document Server

Using the XMM-Newton Slew Survey, we construct a hard-band selected sample of low-luminosity Galactic X-ray sources. Two source populations are represented, namely coronally-active stars and binaries (ASBs) and cataclysmic variables (CVs), with X-ray luminosities collectively spanning the range 10^(28-34) erg/s (2-10 keV). We derive the 2-10 keV X-ray luminosity function (XLF) and volume emissivity of each population. Scaled to the local stellar mass density, the latter is found to be 1.08 +/- 0.16 x 10^28 erg/s/M and 2.5 +/- 0.6 x 10^27 erg/s/M, for the ASBs and CVs respectively, which in total is a factor 2 higher than previous estimates. We employ the new XLFs to predict the X-ray source counts on the Galactic plane at l = 28.5 deg and show that the result is consistent with current observational constraints. The X-ray emission of faint, unresolved ASBs and CVs can account for a substantial fraction of the Galactic ridge X-ray emission (GRXE). We discuss a model in which roughly 80 per cent of the 6-10 keV...

Warwick, R S

2014-01-01

251

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

Science.gov (United States)

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.

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

2011-01-01

252

An early separation scheme for the LHC luminosity upgrade  

CERN Document Server

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...

Sterbini, G

2010-01-01

253

Performance evaluation and optimization of the luminosity detector ALFA  

CERN Document Server

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...

Jakobsen, Sune; Grafström, P; Joram, C

2010-01-01

254

LHCb: LHCb Muon System Performance at High Luminosity  

CERN Multimedia

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...

Pinci, D

2013-01-01

255

The HerMES SPIRE submillimeter local luminosity function  

CERN Document Server

Local luminosity functions are fundamental benchmarks for high-redshift galaxy formation and evolution studies as well as for models describing these processes. Determining the local luminosity function in the submillimeter range can help to better constrain in particular the bolometric luminosity density in the local Universe, and Herschel offers the first opportunity to do so in an unbiased way by imaging large sky areas at several submillimeter wavelengths. We present the first Herschel measurement of the submillimeter 0luminosity function and infrared bolometric (8-1000 $\\mu$m) local luminosity density based on SPIRE data from the HerMES Herschel Key Program over 14.7 deg^2. Flux measurements in the three SPIRE channels at 250, 350 and 500 \\mum are combined with Spitzer photometry and archival data. We fit the observed optical-to-submillimeter spectral energy distribution of SPIRE sources and use the 1/V_{max} estimator to provide the first constraints on the monochromatic 250, 350 and ...

Vaccari, M; Franceschini, A; Altieri, B; Amblard, A; Arumugam, V; Auld, R; Aussel, H; Babbedge, T; Blain, A; Bock, J; Boselli, A; Buat, V; Burgarella, D; Castro-Rodriguez, N; Cava, A; Chanial, P; Clements, D L; Conley, A; Conversi, L; Cooray, A; Dowell, C D; Dwek, E; Dye, S; Eales, S; Elbaz, D; Farrah, D; Fox, M; Gear, W; Glenn, J; Solares, E A Gonzalez; Griffin, M; Halpern, M; Hatziminaoglou, E; Huang, J; Ibar, E; Isaak, K; Ivison, R J; Lagache, G; Levenson, L; Lu, N; Madden, S; Maffei, B; Mainetti, G; Mortier, A M J; Nguyen, H T; O'Halloran, B; Oliver, S J; Omont, A; Page, M J; Panuzzo, P; Papageorgiou, A; Pearson, C P; Perez-Fournon, I; Pohlen, M; Rawlings, J I; Raymond, G; Rigopoulou, D; Rizzo, D; Rodighiero, G; Roseboom, I G; Rowan-Robinson, M; Portal, M Sanchez; Schulz, B; Scott, Douglas; Seymour, N; Shupe, D L; Smith, A J; Stevens, J A; Symeonidis, M; Trichas, M; Tugwell, K E; Valiante, E; Valtchanov, I; Vigroux, L; Wang, L; Ward, R; Wright, G; Xu, C K; Zemcov, M

2010-01-01

256

Very high-luminosity infrared galaxies - are they very young?  

International Nuclear Information System (INIS)

It is proposed that most of the very high-luminosity IRAS galaxies, those which emit greater than or equal to 10 to the 12th solar luminosities nearly all in the far infrared out to 100 microns, are very young systems with ages less than or equal to 10 to the 9th years. The luminosity comes largely from stars with masses near 100 solar masses which evolve rapidly, ejecting much of their mass as elements heavier than hydrogen. The gas ejected condenses into dust in circumstellar shells. The prototype star in the Galaxy which shows all of these attributes is Eta Car. It is shown that total masses of order 10 to the 7th-10 to the 8th solar masses condensed into such stars can produce the observed luminosities, and that 10-100 generations of such stars will produce enough dust (about 10 to the 8th solar masses) to explain the observed infrared luminosities. If this hypothesis is correct the composition of gas and dust may well be highly anomalous, and there should be no old stars with ages about 10 to the 10th years present. Initial star formation is probably triggered by interactions with close companion galaxies. 40 references

257

The Luminosity Function of Galaxies in SDSS Commissioning Data  

CERN Document Server

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...

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

258

The critical accretion luminosity for magnetized neutron stars  

CERN Document Server

The accretion flow around X-ray pulsars with a strong magnetic field is funnelled by the field to relatively small regions close to the magnetic poles of the neutron star (NS), the hotspots. During strong outbursts regularly observed from some X-ray pulsars, the X-ray luminosity can be so high, that the emerging radiation is able to stop the accreting matter above the surface via radiation-dominated shock, and the accretion column begins to rise. This border luminosity is usually called the "critical luminosity". Here we calculate the critical luminosity as a function of the NS magnetic field strength $B$ using exact Compton scattering cross section in strong magnetic field. Influence of the resonant scattering and photon polarization is taken into account for the first time. We show that the critical luminosity is not a monotonic function of the B-field. It reaches a minimum of a few 10^{36} erg s^{-1} when the cyclotron energy is about 10 keV and a considerable amount of photons from a hotspot have energy c...

Mushtukov, Alexander A; Tsygankov, Sergey S; Poutanen, Juri

2014-01-01

259

ATLAS Phase II for the High Luminosity Upgrade  

CERN Document Server

After successful LHC operation at the center-of-mass energy of 7 and 8 TeV in 2011 and 2012, plans are actively advancing for a series of upgrades, culminating roughly 10 years from now in the high luminosity LHC (HL-LHC) project, delivering of order five times the LHC nominal instantaneous luminosity along with luminosity levelling. The final goal is to extend the data set from about few hundred fb-1 expected for LHC running to 3000 fb-1 by around 2030. Current planning in ATLAS also has significant upgrades to the detector during the consolidation of the LHC to reach full LHC energy and further upgrades to accommodate running already beyond nominal luminosity this decade. The challenge of coping with HL-LHC instantaneous and integrated luminosity, along with the associated radiation levels, requires further major changes to the ATLAS detector. The designs are developing rapidly for an all-new inner-tracker, significant upgrades in the calorimeter and muon systems, as well as improved triggers and data acqui...

Huffman, B T; The ATLAS collaboration

2013-01-01

260

Transient 42 second X-ray pulsar EXO 2030+375. II. The luminosity dependence of the pulse profile  

International Nuclear Information System (INIS)

During an outburst from the transient, 42 s, X-ray pulsar EXO 2030+375, marked luminosity-dependent changes in pulsar profile were observed. At high luminosities the pulse profile consisted of a smooth asymmetric main pulse separated by about 180 deg in phase from a small interpulse. As the luminosity decreased by a factor of about 100, the relative strength of the two pulses reversed. During a second outburst, the phase-averaged X-ray light curve was punctuated by a series of flares that repeated about every four hours and involved a factor of six increase in intensity. The observed pulse profile is modeled using a simple geometric model where axially symmetric fan and pencil-beams of emission are emitted from two magnetic poles on a rotating neutron star. The profile shows a marked asymmetry which is modeled by offsetting the magnetic dipole axis from the rotation axis of the neutron star. The modeling indicates that, as the luminosity decreased, the dominant beam changed from a fan beam to a pencil-beam configuration. 27 refs

261

Jet Luminosity from Neutrino-Dominated Accretion Flows in GRBs  

CERN Document Server

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 than the energy deposition rate through neutrino annihilation provided that the black hole is spinning rapidly enough. Also, we find a significant jump in the jet luminosity at the transition mass accretion rate between the advection dominated accretion flow (ADAF) regime and the neutrino-dominated accretion flow (NDAF) regime. This may cause the large variability observed in the prompt emission of GRBs.

Kawanaka, Norita

2013-01-01

262

ATLAS Future Plans: Upgrade and the Physics with High Luminosity  

CERN Document Server

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 $\\rm 5x10^{34}\\ cm^{-2}s^{-1}$. 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.

Rajagopalan, S; The ATLAS collaboration

2013-01-01

263

Analysis of Luminosity Data in BaBar  

International Nuclear Information System (INIS)

Luminosity is a value describing the number of interactions between particles when their respective beams collide. The BaBar (B and B-bar) ambient database and the Oracle server contain archived measurements of instantaneous luminosity from two separate detectors. It is important to understand these data to describe the performance of the B-Factory. Extracting these data, the more reliable PEP-II (Positron Electron Two) luminosity detector can be calibrated to the data collected by the more accurate BaBar L3 (Level 3) detector. Using the ROOT programming language and standard BaBar tools for data extraction, graphs and statistics are generated. Some logistical errors contained in the logbook are also corrected. These programs help aid in understanding both what is happening within the B-Factory, as well as the correlations between the interrelationship of detector data and the information recorded in the logbook

264

Variability of the Galactic X-ray binary luminosity function  

Science.gov (United States)

We investigate the effects of variability of Galactic X-ray binaries on the shape of their luminosity function, based on 8-year long monitoring of Galactic X-ray binaries with the RXTE All-Sky Monitor. From these data we construct luminosity functions for timescales from days to weeks, taking into account completeness effects as discussed in Grimm et al. 2002. We study the effects of variability on the shape of the Galactic XRB luminosity function for the whole sample and separately for high-mass and low-mass X-ray binaries. Finally, we discuss the application of these results to Chandra observations of X-ray binaries in other galaxies. We acknowledge support by NASA grant GO2-3135X and NASA LTSA grant NAG5-13056.

Grimm, H.-J.; Zezas, A.; Fabbiano, G.

2004-08-01

265

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.

266

Mass and luminosity evolution of young stellar objects  

CERN Document Server

A model of protostar mass and luminosity evolution in clusters gives new estimates of cluster age, protostar birthrate, accretion rate and mean accretion time. The model assumes constant protostar birthrate, core-clump accretion, and equally likely accretion stopping. Its parameters are set to reproduce the initial mass function, and to match protostar luminosity distributions in nearby star-forming regions. It obtains cluster ages and birthrates from the observed numbers of protostars and pre-main sequence (PMS) stars, and from the modal value of the protostar luminosity. In 31 embedded clusters and complexes the global cluster age is 1-3 Myr, matching available estimates based on optical spectroscopy and evolutionary tracks. This method of age estimation is simpler than optical spectroscopy, and is more useful for young embedded clusters where optical spectrocopy is not possible. In the youngest clusters, the protostar fraction decreases outward from the densest gas, indicating that the local star-forming a...

Myers, Philip C

2012-01-01

267

Reduction of beta* and increase of luminosity at RHIC  

Energy Technology Data Exchange (ETDEWEB)

The reduction of {beta}* beyond the 1m design value at RHIC has been consistently achieved over the last 6 years of RHIC operations, resulting in an increase of luminosity for different running modes and species. During the recent 2007-08 deuteron-gold run the reduction to 0.70 from the design 1m achieved a 30% increase in delivered luminosity. The key ingredients allowing the reduction have been the capability of efficiently developing ramps with tune and coupling feedback, orbit corrections on the ramp, and collimation, to minimize beam losses in the final focus triplets, the main aperture limitations for the collision optics. We will describe the operational strategy used to reduce the {beta}*, at first squeezing the beam at store, to test feasibility, followed by the operationally preferred option of squeezing the beam during acceleration, and the resulting luminosity increase. We will conclude with future plans for the beta squeeze.

Pilat,F.; Bai, M.; Bruno, D.; Cameron, P.; Della Penna, A.; Drees, A.; Litvinenko, V.; Luo, Y.; Malitsky, N.; Marr, G.; Ptitsyn, V.; Satogata, T.; Tepikian, S.; Trbojevic, D.

2009-05-04

268

Cosmicflows-2: I-band Luminosity - HI Linewidth Calibration  

CERN Document Server

In order to measure distances with minimal systematics using the correlation between galaxy luminosities and rotation rates it is necessary to adhere to a strict and tested recipe. We now derive a measure of rotation from a new characterization of the width of a neutral Hydrogen line profile. Additionally, new photometry and zero point calibration data are available. Particularly the introduction of a new linewidth parameter necessitates the reconstruction and absolute calibration of the luminosity-linewidth template. The slope of the new template is set by 267 galaxies in 13 clusters. The zero point is set by 36 galaxies with Cepheid or Tip of the Red Giant Branch distances. Tentatively, we determine H0 = 75 km s-1 Mpc-1. Distances determined using the luminosity-linewidth calibration will contribute to the distance compendium Cosmicflows-2.

Tully, R Brent

2012-01-01

269

RHIC PERFORMANCE AND PLANS TOWARDS HIGHER LUMINOSITY AND HIGHER POLARIZATION  

International Nuclear Information System (INIS)

The Relativistic Heavy Ion Collider (RHIC), the first hadron accelerator and collider consisting of two independent rings, has completed its fourth year of operation since commissioning in 1999. RHIC is designed to provide luminosity over a wide range of beam energies and species, including heavy ions, polarized protons, and asymmetric beam collisions. RHIC has produced physics data at four experiments in runs that include gold-on-gold collisions at various beam energies (9.8, 31, 65, and 100 GeV/u), high-energy polarized proton-proton collisions (100 GeV), and deuteron-gold collisions (100 GeV/u). We review recent machine performance for high-luminosity gold-gold operations and polarized proton operations, including causes and solutions for known operational limits. Plans and progress for luminosity and polarization improvements, electron cooling, and the electron-ion collider eRHIC are discussed

270

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.)

271

Luminosity function of faint galaxies with ultraviolet continuum  

International Nuclear Information System (INIS)

The spatial density of faint galaxies with ultraviolet continuum in the Second Survey of the Byurakan Astrophysical Observatory is determined. The luminosity function of galaxies with ultraviolet continuum can be extended to objects fainter by 1-1.5 magnitudes. The spatial density of such galaxies in the interval of luminosities -16 /sup m/ .5 to -21 /sup m/ .5 is on the average 0.08 of the total density of field galaxies in the same interval of absolute magnitudes. The spatial density of low-luminosity galaxies with ultraviolet continuum is very high. In the interval from -12 /sup m/ .5 to -15 /sup m/ .5 it is 0.23 Mpc-3

272

The ATLAS and CMS Plans for the LHC Luminosity Upgrade  

OpenAIRE

In January 2007 the CERN director general announced the plan for the staged upgrade of the LHC luminosity. The plan foresees a phase 1 upgrade reaching a peak luminosity of $3 \\times 10^{34}$ cm$^{-2}$s$^{-1}$ followed by phase reaching up to $ 10^{35}$ cm$^{-2}$s$^{-1}$. We discuss the physics potential and the experimental challenges of an upgraded LHC running. The detector R&D needed to operate ATLAS and CMS in a very high radiation environment and the expected detector p...

Bortoletto, Daniela

2008-01-01

273

Parallax and Luminosity Measurements of an L Subdwarf  

OpenAIRE

We present the first parallax and luminosity measurements for an L subdwarf, the sdL7 2MASS J05325346+8246465. Observations conducted over three years by the USNO infrared astrometry program yield an astrometric distance of 26.7+/-1.2 pc and a proper motion of 2.6241+/-0.0018"/yr. Combined with broadband spectral and photometric measurements, we determine a luminosity of log(Lbol/Lsun) = -4.24+/-0.06 and Teff = 1730+/-90 K (the latter assuming an age of 5-10 Gyr), comparable...

Burgasser, Adam J.; Vrba, Frederick J.; Le?pine, Se?bastien; Munn, Jeffrey A.; Luginbuhl, Christian B.; Henden, Arne A.; Guetter, Harry H.; Canzian, Blaise C.

2007-01-01

274

The mass-luminosity relationship for solar-type stars  

International Nuclear Information System (INIS)

The mass-luminosity relationship for solar-type stars has been reinvestigated using data from the new edition of the Yale Parallax Catalogue and recently published orbits and mass ratios for the relevant visual double stars. The results of this investigation confirm that to within the errors of the data, the sun lies essentially on the mean relationship for the nearby stars. If there is to be further progress in the definition of the mass-luminosity relationship, then the accuracy of the trigonometric parallaxes must be improved substantially

275

Fast and precise luminosity measurement at the international linear collider  

International Nuclear Information System (INIS)

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. The studies are carried out within the FCAL collaboration. (author)

276

Calibrating Type Ia SNe Using the Planetary Nebula Luminosity Function  

Science.gov (United States)

Using the [O III] 5007 Planetary Nebula Luminosity Function (PNLF) distance indicator, we can double the number of known distances to nearby Type Ia SNe, and hence improve their zero point calibration while searching for systematic offsets in SN Ia luminosities between young populations (spiral galaxy) and old populations (ellipticals). We report three new PNLF distances and two new lower limits for five galaxies (NGC 524, 1316, 1380, 1448, & 4526) that have hosted well-observed Type Ia SNe. From the PNLF, we find a Hubble constant of 75 km/s/Mpc, whereas we derive H_0=72 from Cepheids and H_0=73 from SBF.

Jacoby, G. H.; Phillips, M. M.; Feldmeier, J. J.

277

UV Luminosity Function at z~4, 3, and 2  

OpenAIRE

We use very deep (R_lim=27) UGRI imaging to study the evolution of the faint end of the UV-selected galaxy luminosity function from z~4 to z~2. We find that the number of sub-L* galaxies increases from z~4 to z~3 while the number of bright ones appears to remain constant. We find no evidence for continued evolution to lower redshift, z~2. If real, this differential evolution of the luminosity function suggests that differentially comparing key diagnostics of dust, stellar po...

Sawicki, Marcin; Thomson, David

2005-01-01

278

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

Science.gov (United States)

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.

Rakshit, Suvendu; Petrov, Romain G.

2014-07-01

279

Towards a Precise Parton Luminosity Determination at the CERN LHC  

CERN Document Server

A new approach to determine the LHC luminosity is investigated. Instead of employing the proton-proton luminosity measurement, we suggest to measure directly the parton-parton luminosity. It is shown that the electron and muon pseudorapidity distributions, originating from the decay of W+, W- and Z0 bosons produced at 14 TeV pp collisions (LHC), constrain the x distributions of sea and valence quarks and antiquarks in the range from about 3 x 10**-4 to about 10**-1 at a Q**2 of about 10**4 GeV**2. Furthermore, it is demonstrated that, once the quark and antiquark structure functions are constrained from the W+,W- and Z0 production dynamics, other quark-antiquark related scattering processes at the LHC like q-qbar --> W+W- can be predicted accurately. Thus, the lepton pseudorapidity distributions provide the key to a precise parton luminosity monitor at the LHC, with accuracies of about +-1% compared to the so far considered goal of +-5%.

Dittmar, Michael; Zürcher, D

1997-01-01

280

High Luminosity Issues for DAPhNE Upgrade  

OpenAIRE

We give an overview of presentations and discussions during the Accelerator Working Group Session dedicated to High Luminosity Issues for a future upgrade of the Frascati e+e- Phi-Factory DAPhNE at the Workshop "e+e- in the 1-2 GeV range: Physics and Accelerator Prospects" held at Alghero (Italy) on 10-13 September 2003.

Ruggierocern, F.; Zobovlnf Infn, M.

2004-01-01

281

An asymmetric muon-proton Collider: Luminosity Consideration  

International Nuclear Information System (INIS)

An asymmetric muon-proton collider is proposed as an instrument for possible quark structure search. Energy of proton beam is supposed to be some 5-6 times of muon energy. Estimated luminosity of the collider with two rings--the Tevatron accelerator and ?-ring--is found to be of the order of 1033 s-1 cm-2

282

A scheme to improve the low energy luminosity in LEP  

International Nuclear Information System (INIS)

In the design of large electron positron colliding beam facilities, it has become customary to use a certain optimization procedure to establish desired beam performance. The results of this procedure are the minimum requirements in terms of RF-power, bending radius and focusing to achieve a desired luminosity at a given energy. This procedure, however, neglects the optimization of the storage ring performance below and above that design energy. Below the design energy the luminosity is optimized by lowering the tune or by use of wiggler magnets. Both methods result in a luminosity scaling like L /approximately/ E2. To improve the luminosity expectation above the design energy, the optimized lattice design has to be changed as has been done in the design of PETRA and PEP. In these designs the cell length was chosen to be only half as long as the optimized cell which requires twice as many quadrupoles. With the reduced cell length it is possible to increase the tune of the storage ring by a much larger amount than it would be possible with a larger lattice cell

283

Luminosity Variations Along Bunch Trains in PEP-II  

Energy Technology Data Exchange (ETDEWEB)

In the spring of 2005 after a long shut-down, the luminosity of the B-Factory PEP-II decreased along the bunch trains by about 25-30%. There were many reasons studied which could have caused this performance degradation, like a bigger phase transient due to an additional RF station in the Low-Energy-Ring (LER), bad initial vacuum, electron cloud, chromaticity, steering, dispersion in cavities, beam optics, etc. The initial specific luminosity of 4.2 sloped down to 3.2 and even 2.8 for a long train (typical: 130 of 144), later in the run with higher currents and shorter trains (65 of 72) the numbers were more like 3.2 down to 2.6. Finally after steering the interaction region for an unrelated reason (overheated BPM buttons) and the consequential lower luminosity for two weeks, the luminosity slope problem was mysteriously gone. Several parameters got changed and there is still some discussion about which one finally fixed the problem. Among others, likely candidates are: the LER betatron function in x at the interaction point got reduced, making the LER x stronger, dispersion reduction in the cavities, and finding and fixing a partially shorted magnet.

Decker, F.J.; Boyes, M.; Colocho, W.S.; Novokhatski, A.; Sullivan, M.K.; Turner, J.L.; Weathersby, S.P.; Wienands, U.; Yocky, G.; /SLAC

2007-05-18

284

The luminosity function and formation rate history of GRBs  

International Nuclear Information System (INIS)

The isotropic luminosity function (LF) and formation rate history (FRH) of long GRBs is by the first time constrained by using jointly both the observed GRB peak-flux and redshift distributions. Our results support an evolving LF and a FRH that keeps increasing after z = 2. We discuss some interesting implications related to these results

285

Finding and characterising WHIM structures using the luminosity density method  

CERN Document Server

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...

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

286

Vertex, Track Reconstruction and Luminosity Monitoring at LHCb  

Science.gov (United States)

The VELO detector plays a key role in the LHCb experiment. It is essential in vertex and track reconstruction. It can also be used to monitor luminosity. A brief description on the track reconstruction algorithm and application are given. A subset of the final VELO detector has been tested in a pion beam at CERN. Some preliminary results are presented.

Wang, J.

287

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 ?*; 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

288

LHC Report: Boost in bunches brings record luminosity  

CERN Multimedia

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...

2011-01-01

289

Potential for luminosity improvement for low-energy RHIC operation  

Energy Technology Data Exchange (ETDEWEB)

At the Brookhaven National Laboratory, a physics program, motivated by the search of the QCD phase transition critical point, requires operation of the Relativistic Heavy Ion Collider (RHIC) with heavy ions at very low beam energies corresponding to 2.5-20 GeV/n. Several physics runs were already successfully performed at these low energies. However, the luminosity is very low at lowest energies of interest (< 10 GeV/n) limited by the intra-beam scattering and space-charge, as well as by machine nonlinearities. At these low energies, electron cooling could be very effective in counteracting luminosity degradation due to the IBS, while it is less effective against other limitations. Overall potential luminosity improvement for low-energy RHIC operation from cooling is summarized for various energies, taking into account all these limitations as well as beam lifetime measured during the low-energy RHIC runs. We also explore a possibility of further luminosity improvement under the space-charge limitation.

Fedotov A. V.

2012-05-20

290

Physics of a high-luminosity Tau-Charm Factory  

International Nuclear Information System (INIS)

This paper highlights the physics capabilities of a Tau-Charm Factory; i.e., high luminosity (?1033cm-2s-1) e+e- collider operating in the center-of-mass energy range of 3-5 GeV, with a high-precision, general-purpose detector. Recent developments in ? and charm physics are emphasized

291

Direct Oxygen Abundances for Low Luminosity LVL Galaxies  

CERN Document Server

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....

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

292

A new record peak luminosity for the LHC  

CERN Multimedia

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...

CERN Bulletin

2010-01-01

293

Calorimeters for absolute luminosity at upgraded DA?NE  

International Nuclear Information System (INIS)

This paper describes the LUMI project which aims at providing fast, reliable and absolute luminosity measurements at the modified DA?NE interaction point in Frascati for testing the new 'crabbed waist' scheme. We present a description of the experimental setup (two luminometers, LUMI1 and LUMI2), the simulation framework developed for this project and summarize the results and performances.

294

Review of mini beta luminosities in PETRA at different energies  

International Nuclear Information System (INIS)

The mini beta operation with PETRA started in March 1981. Since that time many data were taken at 17, 11 and 7 GeV. The maximum luminosities, tune shifts, limitations etc. are summarized and compared in this note. (orig./HSI)

295

Status of studies for luminosity measurement at PANDA detector  

Energy Technology Data Exchange (ETDEWEB)

A good luminosity monitoring is crucial for the PANDA experiment at the planned antiproton accelerator HESR (FAIR, Darmstadt, Germany). For the measurement of the luminosity one can use the elastic antiproton-proton scattering at extreme forward angles. This exploits the fact that the elastic scattering in the range of very small momentum transfer (and thus very small scattering angle) can be calculated exactly from QED. At larger scattering angles the hadronic component of the elastic scattering dominates and this has to be taken from models based on measurements. The current design for the luminosity monitor are four planes of eight thin double-sided silicon microstrip detectors with trapezoidal shape. The detector itself has an angular acceptance from 3 to 8 mrad and good spatial resolution due to using sensors with high resolution (50 {mu}m pitch). There is no particle identification foreseen yet. In this talk an overview of the basic concept and Monte Carlo based performance studies is presented. In more detail studies we show which number of ghost tracks and tracks from inelastic reactions are expected in the luminosity monitor and how they can be reduced or suppressed.

Karavdina, Anastasia [Institut fuer Kernphysik, Universitaet Mainz (Germany); Denig, Achim; Fritsch, Miriam [Institut fuer Kernphysik, Universitaet Mainz (Germany); Helmholtz-Institut Mainz (Germany); Jasinski, Prometeusz; Michel, Mathias; Weber, Tobias [Helmholtz-Institut Mainz (Germany); Collaboration: PANDA-Collaboration

2012-07-01

296

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

297

ON THE RADIO AND OPTICAL LUMINOSITY EVOLUTION OF QUASARS  

International Nuclear Information System (INIS)

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 multi-variate 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 the population of quasars exhibits strong positive correlation between the radio and optical luminosities. With this correlation, whether intrinsic or observationally induced accounted for, we 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 careio-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 for the range of R values considered. 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 sample considered.

298

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] ?4363 line at a strength of 4? 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 ?m 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 ?m 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 ? = 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 probtionships 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 (? = 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 ?m 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 ? = 0.14, which is in agreement with previous studies.

299

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

CERN Document Server

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...

Rakshit, Suvendu

2014-01-01

300

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

Energy Technology Data Exchange (ETDEWEB)

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: L{sub 15{mu}m}{proportional_to}L{sup 0.74{+-}0.06}{sub HX}. 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{sub Disk}, is approximately proportional to the luminosity of the corona in the 2-300 keV energy band, L{sub Corona}, with the L{sub Disk}/L{sub Corona} ratio varying by a factor of 2.1 around a mean value of 1.6. This ratio is a factor of {approx}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 {approx}(1-3) Multiplication-Sign 10{sup 40} erg s{sup -1} Mpc{sup -3}. Finally, the Compton temperature ranges between kT{sub c} Almost-Equal-To 2 and Almost-Equal-To 6 keV for nearby AGNs, compared to kT{sub c} Almost-Equal-To 2 keV for typical quasars, confirming that radiative heating of interstellar gas can play an important role in regulating SMBH growth.

Sazonov, S.; Churazov, E.; Krivonos, R.; Revnivtsev, M.; Sunyaev, R.; Vikhlinin, A. [Space Research Institute, Russian Academy of Sciences, Profsoyuznaya 84/32, Moscow 117997 (Russian Federation); Willner, S. P.; Goulding, A. D.; Jones, C.; Murray, S. S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Hickox, R. C. [Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, NH 03755 (United States); Gorjian, V.; Werner, M. W. [Jet Propulsion Laboratory, California Institute of Technology, MS 169-327, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Fabian, A. C. [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom); Forman, W. R. [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching (Germany)

2012-10-01

301

Low-luminosity X-ray sources and the Galactic ridge X-ray emission  

Science.gov (United States)

Using the XMM-Newton slew survey, we construct a hard-band selected sample of low-luminosity Galactic X-ray sources. Two source populations are represented, namely coronally active stars and binaries (ASBs) and cataclysmic variables (CVs), with X-ray luminosities collectively spanning the range 1028-34 erg s-1 (2-10 keV). We derive the 2-10 keV X-ray luminosity function (XLF) and volume emissivity of each population. Scaled to the local stellar mass density, the latter is found to be 1.08 ± 0.16 × 1028 and 2.5 ± 0.6 × 10^{27} {erg s}^{-1} M_{{?}}^{-1}, for the ASBs and CVs, respectively, which in total is a factor of 2 higher than previous estimates. We employ the new XLFs to predict the X-ray source counts on the Galactic plane at l = 28.5° and show that the result is consistent with current observational constraints. The X-ray emission of faint, unresolved ASBs and CVs can account for a substantial fraction of the Galactic ridge X-ray emission (GRXE). We discuss a model in which ˜80 per cent of the 6-10 keV GRXE intensity is produced in this way, with the remainder attributable to X-ray scattering in the interstellar medium and/or young Galactic source populations. Much of the hard X-ray emission attributed to the ASBs is likely to be produced during flaring episodes.

Warwick, R. S.

2014-11-01

302

Luminosity Measurement at ATLAS with a Scintillating Fiber Tracker  

CERN Document Server

We are reporting about a scintillating fiber tracking detector which is proposed for a precise determination of the absolute luminosity of the CERN LHC at interaction point 1 where the ATLAS experiment is located. The detector needs to track protons elastically scattered under micro-radian angles in direct vicinity to the LHC beam. It is based on square shaped scintillating plastic fibers read out by multi-anode photomultiplier tubes and is housed in Roman Pots. We describe the design and construction of prototype detectors and the results of two beam test experiments carried out at DESY and at CERN. The excellent detector performance established in these tests validates the detector design and supports the feasibility of the proposed challenging method of luminosity measurement. All results from the CERN beam test should be considered as preliminary.

Ask, S

2007-01-01

303

Intermediate-Band Photometric Luminosity Descrimination for M Stars  

Science.gov (United States)

Synthetic photometry has been used to design an intermediate-band filter to be used with CCD cameras to facilitate the luminosity classification of M stars. Spectrophotometric data published by Gunn & Stryker (1983) were used to test various bandwidths and centers. Based on these calculations an intermediate-band filter has been purchased. This filter is being used in conjunction with standard BVRI filters to test its effectiveness in luminosity classification of M stars having a wide range of temperatures and different chemical compositions. The results of the theoretical calculations, filter design specifications and preliminary results of the testing program are presented. This research is supported in part by funds provided by Ball State University, The Fund for Astrophysical Research and the Indiana Academy of Science.

Robertson, T. H.; Furiak, N. M.

1995-12-01

304

Silicon Sensors for Trackers at High-Luminosity Environment  

CERN Document Server

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 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 the one of 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 ...

Peltola, Timo

2014-01-01

305

L1 track triggering at CMS for High Luminosity LHC  

Science.gov (United States)

The High Luminosity LHC (HL-LHC) is expected to deliver luminosities of 5 × 1034 c -2 -1, with an average number of overlapping proton-proton collisions per bunch crossing (pileup) of about 140. These extreme pileup conditions place stringent requirements on the experiments' trigger systems to cope with the resulting event rates. For the CMS experiment, a key component of the detector upgrade for the HL-LHC is a track-trigger system which would identify tracks with transverse momentum above 2 GeV already at the first-level (L1) trigger. Here, a proposal for implementing L1 tracking using ``tracklets" is presented. The expected performance of the L1 tracking from simulation studies and the use of L1 tracks to define trigger objects are discussed.

Skinnari, L.

2014-10-01

306

Offline software for the luminosity detector at PANDA  

International Nuclear Information System (INIS)

The precise determination of the luminosity is crucial for the PANDA experiment which will be built at the new antiproton accelerator HESR (FAIR, Darmstadt, Germany). For this measurement elastic antiproton-proton scattering can be used. In the range of very small momentum transfer this process can be calculated exactly from QED. Therefore we are going to perform measurements at very small momentum transfer (and thus very small scattering angle). The current design for the detector has four planes (10/20 cm in between). It is located outside the magnetic field, 11 m behind the interaction point. Our reconstruction software includes standard parts as hit reconstruction, track finding and track fitting and specific procedures for luminosity extraction and background treatment. Beside these algorithms we developed a software alignment procedure based on reconstructed tracks by using the Millipede algorithm. In this talk an overview of the basic concept and Monte Carlo based performance studies is presented.

307

Can C IV emission be used as a luminosity indicator  

International Nuclear Information System (INIS)

A careful examination is made of the claims of previous authors that the equivalent width of emission lines such as CIV in QSOs can be used as an indicator of the luminosity of the QSO, and also of the alternative claim that the line flux may be useful as a 'standard candle'. It is shown that the competing claims arise from different approaches to the statistical analysis. It is also shown that the observed correlation between emission-line equivalent width Wsub(lambda) and continuum luminosity L may be chiefly due to the variability of QSOs with flat radio spectra, for which the correlation is most pronounced. Objects so prone to vary hardly make the best 'standard candles'. (author)

308

Fast Polycrystalline-CdTe Detectors for LHC Luminosity Measurements  

CERN Document Server

Beam diagnostics in future high-energy accelerators will require long lived instrumentation in highly hostile radiation environments. A research program aiming at individuating new solutions and testing them under extreme operational conditions has been launched at CERN in the framework of developments for the LHC instrumentation. Its outcome might be used in future accelerator projects, in industry or in physics applications. The detectors which will be adopted for the LHC luminosity monitoring and optimization will be installed close to or inside copper absorbers specifically designed for radiation protection of the accelerator magnetic elements in the interaction regions. These detectors will have to withstand extreme radiation levels and their long-term operation has to be assured without requiring human intervention. Polycrystalline-CdTe detectors have demonstrated their radiation hardness against extreme doses of X-ray exposure in the LEP collider and are considered as good candidates for LHC luminosity...

Rossa, E; Placidi, Massimo; Schmickler, Hermann; Brambilla, A; Mongellaz, F; Verger, L; Cindro, V; Mikuz, M; Moritz, P

2002-01-01

309

Luminosity variations in several parallel auroral arcs before auroral breakup  

Directory of Open Access Journals (Sweden)

Full Text Available Variation of the luminosity in two parallel auroral arcs before auroral breakup has been studied by using digitised TV-data with high temporal and spatial resolution. The intervals when a new arc appears near already existing one were chosen for analysis. It is shown, for all cases, that the appearance of a new arc is accompanied by fading or disappearance of another arc. We have named these events out-of-phase events, OP. Another type of luminosity variation is characterised by almost simultaneous enhancement of intensity in the both arcs (in-phase event, IP. The characteristic time of IP events is 10–20 s, whereas OP events last about one minute. Sometimes out-of-phase events begin as IP events. The possible mechanisms for OP and IP events are discussed.

V. Safargaleev

310

A practical high-energy high-luminosity ?+ - ?- collider  

International Nuclear Information System (INIS)

We present a candidate design for a high-energy high-luminosity ?+-? collider, with Ecm = 4 TeV, L = 3 x 104cm-2s-1, using only existing technology. The design uses a rapid-cycling medium-energy proton synchrotron, which produces proton beam pulses which are focused onto two ?-producing targets, with two ?-decay transport lines producing ?+'s. The ?'s are collected, rf-rotated, cooled and compressed into a recirculating linac for acceleration, and then transferred into a storage ring collider. The keys to high luminosity are maximal ? collection and cooling; innovations with these goals are presented, and future plans for collider development are discussed. This example demonstrates a novel high-energy collider type, which will permit exploration of elementary particle physics at energy frontiers beyond the reach of currently existing and proposed electron and hadron colliders

311

Using Micromegas in ATLAS to Monitor the Luminosity  

CERN Document Server

Five small prototype micromegas detectors were positioned in the ATLAS detector during LHC running at $\\sqrt{s} = 8\\, \\mathrm{TeV}$. A $9\\times 4.5\\, \\mathrm{cm^2}$ two-gap detector was placed in front of the electromagnetic calorimeter and four $9\\times 10\\, \\mathrm{cm^2}$ detectors on the ATLAS Small Wheels, the first station of the forward muon spectrometer. The one attached to the calorimeter was exposed to interaction rates of about $70\\,\\mathrm{kHz/cm^2}$ at ATLAS luminosity $\\mathcal{L}=5\\times 10^{33}\\,\\mathrm{cm^{-2}s^{-1}}$ two orders of magnitude higher than the rates in the Small Wheel. We compare the currents drawn by the detector installed in front of the electromagnetic calorimeter with the luminosity measurement in ATLAS experiment.

The ATLAS collaboration

2013-01-01

312

L1 Track Triggering at CMS for High Luminosity LHC  

CERN Document Server

The High Luminosity LHC (HL-LHC) is expected to deliver luminosities of $5 \\times 10^{34}$~cm$^{-2}$s$^{-1}$, with an average number of overlapping proton-proton collisions per bunch crossing (pileup) of about 140. These extreme pileup conditions place stringent requirements on the experiments' trigger systems to cope with the resulting event rates. For the CMS experiment, a key component of the detector upgrade for the HL-LHC is a track-trigger system which would identify tracks with transverse momentum above 2 GeV already at the first-level (L1) trigger. Here, a proposal for implementing L1 tracking using "tracklets" is presented. The expected performance of the L1 tracking from simulation studies and the use of L1 tracks to define trigger objects are discussed.

Skinnari, Louise

2014-01-01

313

Offline software for the luminosity detector at PANDA  

Energy Technology Data Exchange (ETDEWEB)

The precise determination of the luminosity is crucial for the PANDA experiment which will be built at the new antiproton accelerator HESR (FAIR, Darmstadt, Germany). For this measurement elastic antiproton-proton scattering can be used. In the range of very small momentum transfer this process can be calculated exactly from QED. Therefore we are going to perform measurements at very small momentum transfer (and thus very small scattering angle). The current design for the detector has four planes (10/20 cm in between). It is located outside the magnetic field, 11 m behind the interaction point. Our reconstruction software includes standard parts as hit reconstruction, track finding and track fitting and specific procedures for luminosity extraction and background treatment. Beside these algorithms we developed a software alignment procedure based on reconstructed tracks by using the Millipede algorithm. In this talk an overview of the basic concept and Monte Carlo based performance studies is presented.

Karavdina, Anastasia [Mainz Univ. (Germany). Inst. fuer Kernphysik; Denig, Achim; Feldbauer, Florian; Fritsch, Miriam; Jasinski, Prometeusz; Leithoff, Heinrich; Michel, Mathias; Pflueger, Stefan; Weber, Tobias [Mainz Univ. (Germany). Inst. fuer Kernphysik; Helmholtz-Institut Mainz (Germany); Collaboration: PANDA-Collaboration

2013-07-01

314

Low-Luminosity embedded sources and their environs  

Science.gov (United States)

A far-infrared and submillimeter study of regions within 0.03 pc of the low-luminosity sources embedded in the clouds B335, L723, B361, L1455, and L1551 is presented along with CO molecular line results on the extended environments of these sources out to 0.3 pc. Three of the embedded objects are definite bipolar outflow sources, one may be associated with an observed outflow, and one has no observable outflow. Data on the outflows are combined with determination of the luminosity of the embedded objects, and of the temperature and matter distribution about the sources, to infer the evolutionary stage of the embedded sources.

Davidson, J. A.

1987-01-01

315

Infrared line observations of low-luminosity outflow sources  

International Nuclear Information System (INIS)

The present model for an ionized wing, with constant or accelerating velocity and an optical depth in the observed lines of the order of unity, leads to an identification of B5 IRS 1 as the source of an outflow as well as to an estimation of its mass loss rate. This model also furnishes a consistent picture for the sources L1262, L1489, L1536, and L1582, which have only limits to their IR line emission. The data, and their analyses, indicate that the class of outflow objects with low luminosities shows a relatively complex range of outflow parameters and local conditions; this makes the sources qualitatively different from the usual, high luminosity counterparts. 61 references

316

Differential Density Statistics of Galaxy Distribution and the Luminosity Function  

OpenAIRE

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 $dN/dz$ ...

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

2006-01-01

317

Relativistic Cosmology Number Densities and the Luminosity Function  

OpenAIRE

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:astro-ph/0611032) where the galaxy distribution was studied out to z=1. Observational inhomogeneities were detected at this range. This research al...

Iribarrem, Alvaro S.; Lopes, Amanda R.; Ribeiro, Marcelo B.; Stoeger, William R.

2012-01-01

318

Physics potential and experimental challenges of the LHC luminosity upgrade  

OpenAIRE

We discuss the physics potential and the experimental challenges of an upgraded LHC running at an instantaneous luminosity of 10**35 cm-2s-1. The detector R&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 Ne...

Pittau, Roberto

2005-01-01

319

Jet Luminosity from Neutrino-Dominated Accretion Flows in GRBs  

OpenAIRE

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 luminosi...

Kawanaka, Norita

2013-01-01

320

RESOLVING THE LUMINOSITY PROBLEM IN LOW-MASS STAR FORMATION  

International Nuclear Information System (INIS)

We determine the observational signatures of protostellar cores by coupling two-dimensional radiative transfer calculations with numerical hydrodynamical simulations that predict accretion rates that both decline with time and feature short-term variability and episodic bursts caused by disk gravitational instability and fragmentation. We calculate the radiative transfer of the collapsing cores throughout the full duration of the collapse, using as inputs the core, disk, protostellar masses, radii, and mass accretion rates predicted by the hydrodynamical simulations. From the resulting spectral energy distributions, we calculate standard observational signatures (Lbol, Tbol, Lbol/Lsmm) to directly compare to observations. We show that the accretion process predicted by these models reproduces the full spread of observed protostars in both Lbol-Tbol and Lbol-Mcore space, including very low luminosity objects, provides a reasonable match to the observed protostellar luminosity distribution, and resolves the long-standing luminosity problem. These models predict an embedded phase duration shorter than recent observationally determined estimates (0.12 Myr versus 0.44 Myr), and a fraction of total time spent in Stage 0 of 23%, consistent with the range of values determined by observations. On average, the models spend 1.3% of their total time in accretion bursts, during which 5.3% of th accretion bursts, during which 5.3% of the final stellar mass accretes, with maximum values being 11.8% and 35.5% for the total time and accreted stellar mass, respectively. Time-averaged models that filter out the accretion variability and bursts do not provide as good of a match to the observed luminosity problem, suggesting that the bursts are required.

321

Close stars and accretion in Low Luminosity Active Galactic Nuclei  

OpenAIRE

Quasar accretion disks are believed to form stars by self-gravity. Low Luminosity Active Galactic Nuclei (LLAGN) are much dimmer galactic centers, and are often believed to be quasars that ran out of gaseous fuel. LLAGN accretion disks should thus co-exist with thousands to millions of stars or proto-stars left from the previous stronger accretion activity. In principle, these stars may produce several important effects: (i) contribute to the optical/UV spectra of some LLAGN...

Nayakshin, Sergei

2004-01-01

322

LHC abort gap cleaning studies during luminosity operation  

CERN Document Server

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.

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

323

Kinetic Luminosity and Composition of Active Galactic Nuclei Jets  

OpenAIRE

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...

Hirotani, Kouichi

2004-01-01

324

KEKB records 10^34/cm^2s luminosity  

CERN Multimedia

"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).

2003-01-01

325

A new maximum likelihood method for luminosity calibrations  

OpenAIRE

A new statistical parallax method using the Maximum Likelihood principle is presented, allowing the simultaneous determination of a luminosity calibration, kinematic characteristics and spatial distribution of a given sample. This method has been developed for the exploitation of the Hipparcos data and presents several improvements with respect to the previous ones: the effects of the selection of the sample, the observational errors, the galactic rotation and the interstellar absorption are ...

Luri Carrascoso, Xavier; Mennessier, M. O.; Torra Roca, Jorge; Figueras Sin?ol, Francesca

1996-01-01

326

Physics potential and experimental challenges of the LHC luminosity upgrade  

International Nuclear Information System (INIS)

We discuss the physics potential and the experimental challenges of an upgraded LHC running at an instantaneous luminosity of 1035 cm-2s-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.)

327

The optical alignment system for luminosity detector at ILC  

CERN Document Server

The possibility to use semi-transparent silicon detectors to measure the displacement detector luminosity LumiCal, planned for the future linear accelerator ILC / CLIC, was studied using an optical laser system based on these detectors. Preliminary results of measurements were achieved using the prototype of this system provided in the displacement measurement values of the X and Y directions with an accuracy of a few microns.

Banas, E; Kielar, E; Kotula, J; Krupa, B; Moszczynski, A; Oliwa, K; Pawlik, B; Wierba, W; Zawiejski, L

2015-01-01

328

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 d?/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

329

An absolute luminosity monitor for the LHCb experiment  

Science.gov (United States)

A novel method of measuring the absolute luminosity at colliding beam experiments is proposed. The method is based on a measurement of beam-gas interaction vertices to determine beam shapes and overlaps. This method can be applied at the LHCb experiment without the need for any modifications of existing sub-detectors and it is entirely based on the LHCb Vertex Locator (VELO) silicon tracker.

Laštovi?ka, Tomáš

2007-12-01

330

Operating microscope in Endodontics: visual magnification and luminosity  

OpenAIRE

Introduction: The surgical microscope has been used in Endodontics in order to minimize the obscurity of the surgical field, because it provides a high magnification and luminosity, thereby enhancing the procedures performed and providing a final result of higher quality. Objective and literature review: The objective of this study was to review the literature by addressing the current situation of the operating microscope in Endodontics, emphasizing its advantages and limitations. Despite be...

Letícia Moreira Feix; Daiana Boijink; Ronise Ferreira; Márcia Helena Wagner; Fernando Branco Barletta

2010-01-01

331

LHC Luminosity calibration using the Longitudinal Density Monitor  

CERN Document Server

The present note describes how data measured with the LHC Longitudinal Density Monitor (LDM) can contribute to the 2012-2013 LHC luminosity calibration experiments. More specifically, LDM data can provide an estimation of the ghost fraction fghost and satellite fraction fsat needed for the normalisation of bunch populations. After a concise description of the LDM data treatment, the key quantities of interest are derived and commented. Finally, a description of the LDM analysis products is given.

Boccardi, A; Ferro-Luzzi, M; Mazzoni, S; Palm, M

2013-01-01

332

LHC Abort Gap Cleaning Studies During Luminosity Operation  

Energy Technology Data Exchange (ETDEWEB)

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.

Gianfelice-Wendt, E.; /Fermilab; Bartmann, W.; Boccardi, A.; Bracco, C.; Bravin, E.; Goddard, B.; Hofle, W.; Jacquet, D.; Jeff, A.; Kain, V.; Meddahi, M.; /CERN

2012-05-11

333

Calorimeters for absolute luminosity at upgraded DAphiNE  

Energy Technology Data Exchange (ETDEWEB)

This paper describes the LUMI project which aims at providing fast, reliable and absolute luminosity measurements at the modified DAphiNE interaction point in Frascati for testing the new 'crabbed waist' scheme. We present a description of the experimental setup (two luminometers, LUMI1 and LUMI2), the simulation framework developed for this project and summarize the results and performances.

Romano, V; Schioppa, M [Universita della Calabria, Cosenza (Italy); Bossi, F; Buonomo, B; Mazzitelli, G; Murtas, F; Raimondi, P [Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); Arnaud, N; Breton, D; Roudeau, P; Stocchi, A; Variola, A; Viaud, B [LAL, Orsay (France); Valente, P [INFN Roma ' La Sapienza' , Roma (Italy); Branchini, P, E-mail: Paolo.Branchini@roma3.infn.i [Sez. INFN Roma Tre, Roma (Italy)

2009-04-01

334

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

335

ATLAS Inner Tracker Upgrade Simulation for High-Luminosity LHC  

CERN Document Server

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.

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

2013-01-01

336

Prospects for physics at high luminosity with CMS  

OpenAIRE

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 upg...

Varela João

2013-01-01

337

CP stars: Photometric calibrations of luminosity using Hipparcos data  

OpenAIRE

The application of the Stromgren photometric luminosity calibrations to different types of CP stars is reexamined in the light of the new Hipparcos data. A first attempt is made to use the LM statistical parallax method (Luri et al., 1996) -- based on the maximum likelihood principle -- to obtain a calibration of the absolute magnitude as a function of two Stromgren colour indices, thus reflecting effective temperature and evolution. Its application to a sample of Si stars a...

Figueras, F.; Luri, X.; Gomez, A. E.; Torra, J.; Jordi, C.; Mennessier, M. O.; Domingo, A.; Masana, E.; Grenier, S.; Blasi, F.

1998-01-01

338

Semiconductor materials and detectors for future very high luminosity colliders  

CERN Document Server

Recent results from the CERN RD50 Collaboration for the development of radiation-hard detectors for the LHC upgrade (Super-LHC) and in general for very high luminosity colliders are reviewed, summarized and discussed. Particularly, the attention is focused on emerging technologies (Czochralski and Magnetic Czochralski silicon, thinned detectors, highly doped thin epitaxial layer on Czochralski substrate, pre-irradiated silicon, p-type substrate devices) and new detector structures (3D, 3D-STC, Semi-3D, and Stripixel).

Candelori, A

2005-01-01

339

Status of the luminosity monitor for the PANDA experiment  

International Nuclear Information System (INIS)

A good luminosity monitoring is crucial for the PANDA experiment at the planned antiproton accelerator HESR (FAIR, Darmstadt, Germany). For the measurement of the luminosity one can use the elastic antiproton-proton scattering at extreme forward angles. This exploits the fact that the elastic scattering in the range of very small momentum transfer (and thus very small scattering angle) can be calculated exactly from QED. At larger scattering angles the hadronic component of the elastic scattering dominates and this has to be taken from measurements. Unfortunately there are no or only a few data with large uncertainties available in the momentum range we need for PANDA. The current design for the luminosity monitor are four planes of eight double-sided silicon microstrip detectors with trapezoidal shape. The detector itself has an angular acceptance from 3 to 8 mrad and good spatial resolution due to using sensors with high resolution (50 ?m pitch). An overview of the basic concept and Monte Carlo based performance studies within the PANDARoot framework are presented.

340

Precision luminosity measurement at LHCb with beam-gas imaging  

CERN Document Server

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...

Barschel, Colin

341

Luminosities of Barred and Unbarred S0 Galaxies  

CERN Document Server

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...

Bergh, Sidney van den

2012-01-01

342

Enhanced luminosity of young stellar objects in cometary globules  

Science.gov (United States)

In this study we investigated the effects of external trigger on the characteristics of young stellar objects (YSOs) associated with cometary globules (CGs). We made optical spectroscopy of stars associated with star-forming CGs. We find that the masses of the most massive stars associated with CGs are correlated with the masses of the parent cloud but they are systematically larger than expected for clouds of similar mass from the relation M max-star=0.33 M {cl/0.43} given by Larson (Mon. Not. R. Astron. Soc. 200:159, 1982). We have also estimated the luminosities of the IRAS sources found associated with CGs as a function of cloud mass and then compared them with those of the IRAS sources found associated with isolated opacity class 6 clouds (isolated and relatively away from large star forming regions). We find that the luminosities of IRAS sources associated with CGs are larger than those of the opacity class 6 clouds. These findings support results from recent simulations in which it was shown that the Radiation Driven Implosion (RDI) process, believed to be responsible for the cometary morphology and star formation, can increase the luminosity 1 2 orders of magnitudes higher than those of protostars formed without external triggering due to an increase in accretion rates. Thus implying that the massive stars can have profound influence on the star formation in clouds located in their vicinity.

Maheswar, G.; Bhatt, H. C.

2008-06-01

343

Luminosity measurement method for the LHC: The detector requirement studies  

International Nuclear Information System (INIS)

In our earlier paper [1] we have proposed a new luminosity measurement method for the LHC collider. It is based on the detection of lepton pairs produced in the peripheral collisions of the LHC beam particles and allows to reach better than 1% accuracy of the theoretical control of the event rate. In order to implement this method a new, specialized luminosity detector must be incorporated within the fiducial volume of one of the existing LHC detectors. In this paper the requirement studies for such a detector are presented. They are driven, almost exclusively, by its capacity to identify, within the level 1 trigger latency of the host detector, the bunch crossings with exclusive, coplanar pairs of opposite charge particles. It is shown that a tracking detector with the azimuthal hit resolution of 2 mrad allows us to reduce the rate of background events to the requisite O(1kHz) level while retaining a sufficiently large fraction of the signal events for the precise luminosity measurement

344

The rate and luminosity function of Short GRBs  

CERN Document Server

We compare the luminosity function and rate inferred from the BATSE short hard bursts (SHBs) peak flux distribution with the redshift and luminosity distributions of SHBs observed by Swift/HETE II. The Swift/HETE II SHB sample is incompatible with SHB population that follows the star formation rate. However, it is compatible with a distribution of delay times after the SFR. This would be the case if SHBs are associated with binary neutron star mergers. The implied SHB rates that we find range from \\sim 8 to \\sim 30h_{70}^3 Gpc^{-3}yr^{-1}. This rate is a much higher than what was previously estimated and it is comparable to the rate of neutron star mergers estimated from statistics of binary pulsars. If GRBs are produced in mergers the implied rate practically guarantees detection by LIGO II and possibly even by LIGO I, if we are lucky. Our analysis, which is based on observed short hard burst is limited to bursts with luminosities above 10^{49}erg/sec. Weaker bursts may exist but if so they are hardly detect...

Piran, T; Piran, Tsvi; Guetta, Dafne

2006-01-01

345

The Black Hole Mass - Galaxy Luminosity Relationship for SDSS Quasars  

CERN Document Server

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...

Salviander, S; Bonning, E W

2014-01-01

346

Photometric observations of SARS clusters: Galaxy Luminosity Profiles  

CERN Document Server

We have analyzed CCD images of 14 Abell clusters in the R filter of the SARS survey (Way et al 2004), with cz<40000kms^{-1}. We have obtained the luminosity profiles for 507 galaxies of which 232 (46%) have known redshifts. In order to fit the luminosity profiles we used the de Vaucouleurs law for bulge systems, an exponential profile for disk systems and we have also fitted the Sersic's law (r^n) to all galaxy profiles. We have found that 162 (32%) galaxies in the sample have pure r^{1/4} profiles, 168 (33%) have pure exponential profiles, while 93 (18%) galaxies have luminosity profiles that are well fitted by a combination of both bulge and disk profiles. On the other hand, we could not fit the classical bulge + disk profile to the remaining 84 (17%) galaxies of the sample. For such cases we have only used the Sersic law. We have also analyzed how seeing and sky cleaning affect the structural and photometric parameters obtained through profile fitting. In addition, we have studied several relations betw...

Coenda, V; Muriel, H; Quintana, H; Infante, L; Lambas, D G

2004-01-01

347

Molecular gas in nearby low-luminosity QSO host galaxies  

CERN Document Server

This paper addresses the global molecular gas properties of a representative sample of galaxies hosting low-luminosity quasistellar objects. An abundant supply of gas is necessary to fuel both the active galactic nucleus and any circum-nuclear starburst activity of QSOs. We selected a sample of nearby low-luminosity QSO host galaxies that is free of infrared excess biases. All objects are drawn from the Hamburg-ESO survey for bright UV-excess QSOs, have DEC>-30 degrees and redshifts that do not exceed z=0.06. The IRAM 30m telescope was used to measure the CO(1-0) and CO(2-1) transition in parallel. 27 out of 39 galaxies in the sample have been detected. The molecular gas masses of the detected sources range from 0.4E9 M_sun to 9.7E9 M_sun. We can confirm that the majority of galaxies hosting low-luminosity QSOs are rich in molecular gas. The properties of galaxies hosting brighter type I AGN and circumnuclear starformation regions differ from the properties of galaxies with fainter central regions. The overal...

Bertram, T; Fischer, S; Zuther, J; Straubmeier, C; Wisotzki, L; Krips, M

2007-01-01

348

Height distribution of luminosity of molecular nitrogen bands in aurorae  

International Nuclear Information System (INIS)

In rocket experiments performed on Keis island during the winter season of 1972-1973 by means of spectrophotometers intensities of auroral luminosity in the 3000-8000 A spectral range have been measured. The paper deals with the analysis of height distribution of luminosity of the first negative band N2+(0-0)lambda 3914 A and second positive band N2 (0-0)lambda 3371 A of molecular nitrogen in rocket experiments on 13 December 1972. 01.01 UT. and 10 January 1973, 18.34.UT. It is shown that relation volume emission velocities eta (3914)/eta(3371) at heights below 130 km can more than twice exceed the value calculated under the condition of collision interaction of precipitating electron flux with upper atmosphere. Such relatuion values can be satisfactorily explained with regard to collisionless processes in the ionosphere which are developed in bright auroral forms. By the data on auroral luminosity spectral distributions of secondary electron fluxes at different heights are plotted. It is shown that at collective interactions the N2+ lambda 3914 A by secondary electron flux can attain approximately 70%. It is shown that at the turbulent layer boundary (120 km) cobcentration growth of secondary electrons occurs

349

Infrared Luminosity Functions of AKARI-SDSS Galaxies  

CERN Document Server

By cross-correlating AKARI infrared (IR) sources with the SDSS galaxies, we identified 2357 infrared galaxies with a spectroscopic redshift. This is not just one of the largest samples of local IR galaxies, but AKARI provides crucial FIR bands (9, 18, 65, 90, 140, and 160um) in accurately measuring galaxy SED across the peak of the dust emission at ~100um. By fitting modern IR SED models to the AKARI photometry, we measured the total infrared luminosity (L_IR) of individual galaxies more accurately. Using this L_IR, we constructed luminosity functions of infrared galaxies at a median redshift of z=0.031, with 4 times larger sample than previous work. The LF agrees well with that at z=0.0082 (RBGS), showing smooth and continuous evolution toward higher redshift LFs measured in the AKARI NEP deep field. The derived local cosmic IR luminosity density is Omega_IR=3.8x10^8 LsunMpc^-3. We separate galaxies into AGN, star-forming, and composite by using the [NII]/Ha vs [OIII]/Hb line ratios. The fraction of AGN show...

Goto, Tomotsugu; Malkan, Matthew; Takagi, Toshinobu; Inami, Hanae; Pearson, Chris; Wada, Takehiko; Matsuhara, Hideo; Yamauchi, Chisato; Takeuchi, Tsutomu T; Nakagawa, Takao; Oyabu, Shinki; Ishihara, Daisuke; Sanders, David B; Floc'h, Emeric Le; Lee, Hyung Mok; Jeong, Woong-Seob; Serjeant, Stephen; Sedgwick, Chris

2011-01-01

350

Status of the luminosity monitor for the PANDA experiment  

Energy Technology Data Exchange (ETDEWEB)

A good luminosity monitoring is crucial for the PANDA experiment at the planned antiproton accelerator HESR (FAIR, Darmstadt, Germany). For the measurement of the luminosity one can use the elastic antiproton-proton scattering at extreme forward angles. This exploits the fact that the elastic scattering in the range of very small momentum transfer (and thus very small scattering angle) can be calculated exactly from QED. At larger scattering angles the hadronic component of the elastic scattering dominates and this has to be taken from measurements. Unfortunately there are no or only a few data with large uncertainties available in the momentum range we need for PANDA. The current design for the luminosity monitor are four planes of eight double-sided silicon microstrip detectors with trapezoidal shape. The detector itself has an angular acceptance from 3 to 8 mrad and good spatial resolution due to using sensors with high resolution (50 {mu}m pitch). An overview of the basic concept and Monte Carlo based performance studies within the PANDARoot framework are presented.

Karavdina, Anastasia; Denig, Achim; Fritsch, Miriam; Lauth, Werner; Michel, Mathias; Panzenboeck, Elisabeth; Weber, Tobias [Institut fuer Kernphysik, Universitaet Mainz (Germany); Collaboration: PANDA-Collaboration

2011-07-01

351

Infrared Luminosities and Dust Properties of z ~ 2 Dust-Obscured Galaxies  

CERN Document Server

We present SHARC-II 350um imaging of twelve 24um-bright (F_24um > 0.8 mJy) Dust-Obscured Galaxies (DOGs) and CARMA 1mm imaging of a subset of 2 DOGs, all selected from the Bootes field of the NOAO Deep Wide-Field Survey. Detections of 4 DOGs at 350um imply IR luminosities which are consistent within a factor of 2 of expectations based on a warm dust spectral energy distribution (SED) scaled to the observed 24um flux density. The 350um upper limits for the 8 non-detected DOGs are consistent with both Mrk231 and M82 (warm dust SEDs), but exclude cold dust (Arp220) SEDs. The two DOGs targeted at 1mm were not detected in our CARMA observations, placing strong constraints on the dust temperature: T_dust > 35-60 K. Assuming these dust properties apply to the entire sample, we find dust masses of ~3x10^8 M_sun. In comparison to other dusty z ~ 2 galaxy populations such as sub-millimeter galaxies (SMGs) and other Spitzer-selected high-redshift sources, this sample of DOGs has higher IR luminosities (2x10^13 L_sun vs....

Bussmann, R S; Borys, C; Desai, V; Jannuzi, B T; Le Floc'h, E; Melbourne, J; Sheth, K; Soifer, B T

2009-01-01

352

An analytical approximation of the luminosity distance in flat cosmologies with a cosmological constant  

CERN Document Server

We present an analytical approximation formula for the luminosity distance in spatially flat cosmologies with dust and a cosmological constant. Apart from the overall factor, the effect of non-zero cosmological constant in our formula is written simply in terms of a rational function. We also show the approximate formulae for the Dyer-Roeder distance (empty beam case) and the generalized angular diameter distance from redshift $z_1$ to $z_2$, which are particularly useful in analyzing the gravitational lens effects. Our formulae are widely applicable over the range of the density parameter and the redshift with sufficiently small uncertainties. In particular, in the range of density parameter $0.3 \\leq \\Omega_{\\rm m} \\leq 1$ and redshift $0.03 \\leq z \\leq 1000$, the relative error for the luminosity distance by our formula is always smaller than that of the recent work by Wickramasinghe and Ukwatta (2010). Hence, we hope that our formulae will be an efficient and useful tool for exploring various problems in ...

Adachi, Masaru

2011-01-01

353

Radiative Transfer Modeling of Lyman Alpha Emitters: I. Statistics of Spectra and Luminosity  

CERN Document Server

We combine a cosmological reionization simulation with box size of 100Mpc/h on a side and a Monte Carlo Lyman-alpha (Lya) radiative transfer code to model Lyman Alpha Emitters (LAEs) at z~5.7. The model introduces Lya radiative transfer as the single factor for transforming the intrinsic Lya emission properties into the observed ones. Spatial diffusion of Lya photons from radiative transfer results in extended Lya emission and only the central part with high surface brightness can be observed. Because of radiative transfer, the appearance of LAEs depends on density and velocity structures in circumgalactic and intergalactic media as well as the viewing angle, which leads to a broad distribution of apparent (observed) Lya luminosity for a given intrinsic Lya luminosity. Radiative transfer also causes frequency diffusion of Lya photons. The resultant Lya line is asymmetric with a red tail. The peak of the Lya line shifts towards longer wavelength and the shift is anti-correlated with the apparent to intrinsic L...

Zheng, Zheng; Trac, Hy; Miralda-Escude, Jordi

2009-01-01

354

A POPULATION OF METAL-POOR GALAXIES WITH ?L* LUMINOSITIES AT INTERMEDIATE REDSHIFTS  

International Nuclear Information System (INIS)

We present new spectroscopy and metallicity estimates for a sample of 15 star-forming galaxies with redshifts in the range 0.29-0.42. These objects were selected in the KPNO International Spectroscopic Survey via their strong emission lines seen in red objective-prism spectra. Originally thought to be intermediate-redshift Seyfert 2 galaxies, our new spectroscopy in the far red has revealed these objects to be metal-poor star-forming galaxies. These galaxies follow a luminosity-metallicity (L - Z) relation that parallels the one defined by low-redshift galaxies, but is offset by a factor of more than 10 to lower abundances. The amount of chemical and/or luminosity evolution required to place these galaxies on the local L-Z relation is extreme, suggesting that these galaxies are in a very special stage of their evolution. They may be late-forming massive systems, which would challenge the current paradigm of galaxy formation. Alternatively, they may represent intense starbursts in dwarf-dwarf mergers or a major infall episode of pristine gas into a pre-existing galaxy. In any case, these objects represent an extreme stage of galaxy evolution taking place at relatively low redshift.

355

Evolution of the Blue Luminosity-to-Baryon Mass Ratio of Clusters of Galaxies  

CERN Document Server

We derive the ratio of total blue luminosity to total baryon mass, LB/Mb, for massive (Mgas at the Abell radius is \\ge 1 \\times 10^{13} h^{-2.5} \\Msolar) clusters of galaxies up to z \\simeq 1 from the literature. Twenty-two clusters in our sample are at z > 0.1. Assuming that the relative mix of hot gas and galaxies in clusters does not change during cluster evolution, we use LB/Mb to probe the star formation history of the galaxy population as a whole in clusters. We find that LB/Mb of clusters increases with redshift from LB/Mb=0.024 (solar units) at z = 0 to \\simeq 0.06 at z=1, indicating a factor of 2-3 brightening (we assume H0=70 km/s/Mpc). This amount of brightening is almost identical to the brightening of the M/LB ratio of early-type galaxies in clusters at 0.02 \\le z \\le 0.83 reported by van Dokkum et al. (1998). We compare the observed brightening of LB/Mb with luminosity evolution models for the galaxy population as a whole, changing the e-folding time of star formation brightening, while models w...

Shimasaku, K

2000-01-01

356

Upgraded readout electronics for the ATLAS LAr Calorimeter at the High Luminosity LHC  

CERN Document Server

The ATLAS Liquid Argon (LAr) calorimeters produce a total of 182,486 signals which are digitized and processed by the front-end and back-end electronics at every triggered event. In addition, the front-end electronics is summing analog signals to provide coarsely grained energy sums, called trigger towers, to the first-level trigger system, which is optimized for nominal LHC luminosities. However, the pile-up noise expected during the High Luminosity phases of LHC will be increased by factors of 3 to 7. An improved spatial granularity of the trigger primitives is therefore proposed in order to improve the identification performance for trigger signatures, like electrons or photons, at high background ejection rates. For the first upgrade phase [1] in 2018, new digital tower builder boards (sTBB) are being designed to receive higher granularity signals, digitize them on detector and send them via fast optical links to a new digital processing system (DPS). The DPS applies a digital filtering and identifies sig...

Andeen, T; The ATLAS collaboration

2012-01-01

357

The Black Hole Mass-Bulge Luminosity Relationship for Active Galactic Nuclei from Reverberation Mapping and Hubble Space Telescope Imaging  

DEFF Research Database (Denmark)

We investigate the relationship between black hole mass and bulge luminosity for AGNs with reverberation-based black hole mass measurements and bulge luminosities from two-dimensional decompositions of Hubble Space Telescope host galaxy images. We find that the slope of the relationship for AGNs is 0.76-0.85 with an uncertainty of ~0.1, somewhat shallower than the M_BH \\propto L^{1.0+/-0.1} relationship that has been fit to nearby quiescent galaxies with dynamical black hole mass measurements. This is somewhat perplexing, as the AGN black hole masses include an overall scaling factor that brings the AGN M_BH-sigma relationship into agreement with that of quiescent galaxies. We discuss biases that may be inherent to the AGN and quiescent galaxy samples and could cause the apparent inconsistency in the forms of their M_BH-L_bulge relationships.

Bentz, Misty C.; Peterson, Bradley M.

2008-01-01

358

The X-ray luminosity function of Abell clusters at a redshift of 0.25  

Science.gov (United States)

The X-ray luminosity function of Abell clusters was determined from a sample with mean redshift 0.25. This luminosity function is the same within the errors to that at low redshift. The time scale for changes in the X-ray luminosity of clusters of galaxies is thus greater than 4.0 billion years.

Henry, J. P.; Lavery, R. J.

1984-01-01

359

Discovery of multiple low-luminosity X-ray sources in NGC 6397  

Science.gov (United States)

New low-luminosity X-ray sources have been discovered in NGC 6397 with the ROSAT High Resolution Imager. These sources have a total number, spatial distribution, and X-ray luminosities consistent with their being CVs. The findings supports the hypothesis that the low-luminosity X-ray sources in clusters are generally dominated by CVs.

Cool, Adrienne M.; Grindlay, Jonathan E.; Krockenberger, Martin; Bailyn, Charles D.

1993-01-01

360

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

361

LUMINOSITY-METALLICITY RELATIONS FOR BLUE COMPACT DWARF GALAXIES IN THE OPTICAL AND NEAR-INFRARED  

International Nuclear Information System (INIS)

In this paper, we present systematic studies on the B-, R- and Ks -band luminosity-metallicity (L-Z) relations for a set of metal-poor, blue compact dwarf galaxies (BCDs). Metallicity is derived by using both the empirical N2 and the direct Te methods. Our work reconciles contradictory results obtained by different authors and shows that the L-Z relationship does also hold for BCDs. The empirical N2-based slope of the L-Z relation, for each photometric band, is consistent with the Te -based one. We confirm that the slope of the L-Z relation is shallower in the near-infrared than that in the optical. Our investigations on the correlations between the LB -Z relation residuals and different galactic parameters show that the star formation activities could be a cause of the large scatter in the optical L-Z relationships, whereas the internal absorption might be another possible contributing factor.

362

Tolman's Luminosity-Distance, Poincare's Light-Distance and Cayley-Klein's Hyperbolic Distance  

CERN Document Server

We deduce Tolman's formula of luminosity-distance in Cosmology from Poincare's definition of light-distance with Lorentz Transformation (LT).In Minkowskian metric, if distance is proper time (as it is often argued) then light-distance must be also the shortest distance, like proper duration (unlike Einstein's longest length within rest system). By introducing Poincare's proper light-distance in Einstein's basic synchronization we deduce a dilated distance between observer and receding mirror (with relativistic Doppler factor). Such a distance corresponds not to an Euclidean distance (Einstein's rigid rod) but to an Hyperbolic distance (Cayley-Klein) with a Lobatchevskian Horizon. From a basic proportionality hyperbolic distance-velocity, we deduce the law of Hubble. By following Penrose's Lobatchevskian representation of LT, we transform Special Relativity (SR) into an Hyperbolic Cosmological Relativity (HCR). by using only the LT but the whole LT. In Hyperbolic Rotation motion (basic active LT or Einstein's ...

Pierseaux, Yves

2009-01-01

363

Progress on the design of a high luminosity ?+?- collider  

International Nuclear Information System (INIS)

Parameters are presented for a 2 + 2 TeV muon collider with a luminosity of L = 1035 cm-2 s-1. The design is not optimized for performance, neither for cost; however, it does suffice to allow one to make a credible case that a muon collider is a serious possibility for particle physics, that could open up the realm of physics above the 1 TeV scale, allowing, for example, copious production of supersymmetric particles or a detailed study of the strongly-interacting scenario of electroweak symmetry breaking

364

The Luminosity Function of Galaxies in the Hercules Cluster  

OpenAIRE

We have imaged $\\sim$ 1 deg$^{2}$ in the V-band in the direction of the Hercules Cluster (Abell 2151). The data are used to compute for the first time the luminosity function (LF) of galaxies in the cluster down to the dwarf regime (M$_{lim}$ $\\sim$ -13.85). The global LF is well described by a Schechter function (\\cite{schechter76}) with best-fit parameters $\\alpha$ = -1.30 $\\pm$ 0.06 and M$_V$$^*$ = -21.25 $\\pm$ 0.25. The radial dependence of the LF has also been studied, ...

Sa?nchez-janssen, R.; Iglesias-pa?ramo, J.; Mun?oz-tun?o?n, C.; Aguerri, J. A. L.; Vi?lchez, J. M.

2004-01-01

365

The X-Ray Luminosity Function of Active Galactic Nuclei  

CERN Document Server

We derive an X-ray luminosity function for active galactic nuclei (AGN) that accounts for the X-ray source counts in the 0.5-2.0 and 2-10 keV energy ranges, the redshift distribution of AGNs in the ROSAT Deep Survey (RDS), as well as the X-ray background (XRB) from 1-10 keV. We emphasize the role of X-ray absorption, which has a large effect on the faint end of the 2-10 keV source counts, as well as on the integrated X-ray background.

Schmidt, M; Hasinger, G; Trümper, J E; Zamorani, G

1999-01-01

366

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

367

Sky luminosity for Rio de Janeiro City - Brazil  

International Nuclear Information System (INIS)

This paper presents sky luminosity data for Rio de Janeiro City, useful to be used in daylighting design in architecture. The data are presented as monthly graphics that correlate sunshine-hours with the frequency of occurrence during the day of a specific type of sky, that would present one of five defined characteristics (among clear and overcast sky). These results were derived from the knowledge of daily solar radiation and sunshine-hours data, for every day for a twelve year period. (author). 10 refs, 13 figs, 16 tabs

368

LHCb VELO Closing Control, Vertex Resolution and Luminosity Measurement  

CERN Document Server

The LHCb Vertex Locator (VELO) surrounds the collision point at IP8 of the LHC ring and performs precise tracking and vertexing. This silicon micro-strip detector is built in two halves, which each move independently in the transverse plane so as to approach the collision region during data taking, but retract whilst the beams are injected and adjusted. The closing procedure of the VELO is detailed, along with an analysis of the primary vertex resolution and a description of the role of the VELO in the LHCb luminosity measurement.

Redford, S

2010-01-01

369

Low-beta Quadrupole Designs for the LHC Luminosity Upgrade  

CERN Document Server

Several scenarios are considered for the upgrade of the LHC insertions in view of increasing the luminosity beyond 1034 cm-2s-1. In the case of “quadrupole first” option, superconducting low-b quadrupoles with apertures in the range of 90-110 mm are required in view of increased heat loads and beam crossing angles. We present possible low-b quadrupole designs based on existing Nb3Sn and LHC NbTi superconductors, present scaling laws for the magnet parameters and discuss relative advantages of the underlying triplet layouts.

Ostojic, Ranko; Kirby, Glyn; Russenschuck, Stephan

2005-01-01

370

Physics potential of precision measurements of the LHC luminosity  

CERN Document Server

A precision measurement of the LHC luminosity is a key ingredient for its physics program. In this contribution first of all we review the theoretical accuracy in the computation of LHC benchmark processes. Then we discuss the impact of available and future LHC data in global analysis of parton distributions, with emphasis on the treatment of normalization uncertainties. Finally we present some suggestions for the physics opportunities that can become available by measuring ratios of cross sections between the 8 TeV and 7 TeV runs.

Rojo, Juan

2012-01-01

371

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.)

372

Physics potential and experimental challenges of the LHC luminosity upgrade  

Energy Technology Data Exchange (ETDEWEB)

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.)

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

373

The K-band luminosity function of nearby field galaxies  

OpenAIRE

We present a measurement of the K-band luminosity function (LF) of field galaxies obtained from near-infrared imaging of a sample of 345 galaxies selected from the Stromlo-APM Redshift Survey. The LF is well-fitted over the ten magnitude range -26 < M_K < -16 by a Schechter function with parameters alpha = -1.16 +- 0.19, M* = -23.58 +- 0.42, phi* = 0.012 +- 0.008 Mpc^-3 assuming a Hubble constant of H_0 = 100 km/s/Mpc. We have also estimated the LF for two subsets of galaxie...

Loveday, Jon

1999-01-01

374

Optical and Near-IR Field Luminosity Functions  

OpenAIRE

We present preliminary measurements of the b_J and K-band luminosity functions (LFs) of field galaxies obtained from optical and K-band imaging of a sample of galaxies selected from the Stromlo-APM Redshift Survey. The b_J LF is consistent with that previously published from photographic data. The K-band LF has been estimated over a range of 12 magnitudes and is reasonably well fit by a Schechter function with faint-end slope alpha = -1.2.

Loveday, Jon

1998-01-01

375

Radio galaxy host properties spanning three dex in radio luminosity  

OpenAIRE

We describe a major study of radio source host galaxies being carried out with the HST and ground-based facilities. Our sample is selected from 4 complete samples with different radio flux-density limits, giving a range of three orders of magnitude in radio luminosity at a fixed epoch (z=0.5). High-resolution HST WFPC2 imaging shows that all 44 radio galaxies have flux distributions well fit by an r1/4 law and lying on the Kormendy relation defined by lower redshift ellipticals with a shift i...

Willott, Cj; Mclure, Rj; Jarvis, Mj; Rawlings, S.; Hill, Gj; Mitchell, E.; Dunlop, Js

2003-01-01

376

Prospects for physics at high luminosity with CMS  

Directory of Open Access Journals (Sweden)

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.

Varela João

2013-05-01

377

Luminosity function of contact binaries based on the ASAS survey  

OpenAIRE

The luminosity function for contact binary stars of the W~UMa-type is evaluated on the basis of the ASAS photometric project covering all stars south of delta= +28 within a magnitude range 8

Rucinski, Slavek M.

2006-01-01

378

The luminosity function for late M-stars  

International Nuclear Information System (INIS)

A search for low luminosity M-stars is described. A sample is obtained on the basis of (R - I) colour which gives a space density distribution similar to earlier work for Msub(R) < 14, but shows a subsequent increase in space density for the faintest stars. The implications of these stars for the problem of missing mass in the neighbourhood of the sun is discussed. It is concluded that these stars form part of a population of substellar brown dwarfs which may make up the mass deficit in the solar neighbourhood. (author)

379

Cosmological evolution and luminosity function of x-ray selected active galactic nuclei  

International Nuclear Information System (INIS)

The cosmological evolution and the X-ray luminosity function of X-ray selected active galactic nuclei (AGNs) are derived and discussed.The sample used consists of 31 AGNs extracted from a fully identified sample of X-ray sources from the Einstein Observatory Medium Sensitivity Survey and is therefore exclusively defined by its X-ray properties. The distribution in space is found to be strongly nonuniform. The amount of cosmological evolution required by the X-ray data is derived in the framework of pure luminosity evolution and is found to be smaller than the amount determined from optically selected samples. The X-ray luminosity function is derived. It can be satisfactorily represented by a single power law only over a limited range of absolute luminosities. Evidence that the luminosity function flattens at low luminosity or steepens at high luminosity, or both, is presented and discussed

380

The Luminosity Function of the Milky Way Satellites  

CERN Document Server

We quantify the algorithmic detectability of stellar Milky Way satellites in data release 5 (DR5) of the Sloan Digital Sky Survey (SDSS), and use this to estimate the luminosity function of faint satellite galaxies in our halo. We develop a satellite detection algorithm based on the convolution of the DR5 star catalog with a kernel of zero net flux that is the difference of a narrow positive Gaussian and a much wider negative Gaussian, which removes the background star-count level. This permits us to assess the significance of any (positive) detection in terms of deviations of this map. The efficiency of this algorithm is tested by computing the recovery rate of a large set of mock objects added to SDSS DR5 as a function of their luminosity, size and distance from the Sun. Most of the recent Milky Way satellite discoveries, made by SDSS, are shown to lie very close to the survey's detection limits. Calculating the maximum accessible volume $V_{max}$ for all faint detected objects makes it possible for the fir...

Koposov, S; Evans, N W; Hewett, P C; Irwin, M J; Gilmore, G; Zucker, D B; Rix, H -W; Fellhauer, M; Bell, E F; Glushkova, E V

2007-01-01

381

Differential Density Statistics of Galaxy Distribution and the Luminosity Function  

CERN Document Server

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...

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

382

Relativistic Cosmology Number Densities and the Luminosity Function  

CERN Document Server

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

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

2012-01-01

383

Radio Variability Survey of Very Low Luminosity Protostars  

CERN Document Server

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 interstella...

Choi, Minho; Kang, Miju

2014-01-01

384

The faint end of the galaxy luminosity function  

CERN Document Server

We present and discuss optical measurements of the faint end of the galaxy luminosity function down to M_R = -10 in five different local environments of varying galaxy density and morphological content. The environments we studied, in order of decreasing galaxy density, are the Virgo Cluster, the NGC 1407 Group, the Coma I Group, the Leo Group and the NGC 1023 Group. Our results come from a deep wide-angle survey with the NAOJ Subaru 8 m Telescope on Mauna Kea and are sensitive down to very faint surface-brightness levels. Galaxies were identified as group or cluster members on the basis of their surface brightness and morphology. The faintest galaxies in our sample have R ~ 22.5. There were thousands of fainter galaxies but we cannot distinguish cluster members from background galaxies at these faint limits so do not attempt to determine a luminosity function fainter than M_R = -10. In all cases, there are far fewer dwarfs than the numbers of low mass halos anticipated by cold dark matter theory. The mean lo...

Trentham, N; Trentham, Neil

2002-01-01

385

Luminosity functions of LMXBs in different stellar environments  

CERN Document Server

Based on the archival data of Chandra observations of nearby galaxies we study different sub-populations of low-mass X-ray binaries -- dynamically formed systems in globular clusters, in the nucleus of M31 and (presumably primordial) X-ray binaries in the fields of galaxies. Our aim is to produce accurate luminosity distributions of X-ray binaries in different environments, suitable for quantitative comparison with each other and with the output of population synthesis calculations. Our sample includes seven nearby galaxies (M31, Maffei1, Centaurus A, M81, NGC 3379, NGC 4697 and NGC 4278) and the Milky Way, which together provide relatively uniform coverage down to the luminosity limit of e35 erg/s. In total we have detected 185 LMXBs associated with globular clusters, 35 X-ray sources in the nucleus of M31 and 998 field sources of which ~ 365 are expected to be background AGN. We combine these data, taking a special care of accurate incompleteness correction and removal of CXB contamination, and produce lumi...

Zhang, Zhongli; Voss, Rasmus; Sivakoff, Gregory R; Kraft, Ralph P; Brassington, Nicola J; Kundu, Arunav; Jordán, Andrés; Sarazin, Craig

2011-01-01

386

LHC Report: spring cleaning over, bunches of luminosity  

CERN Multimedia

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...

CERN Bulletin

2011-01-01

387

Luminous Satellites II: Spatial Distribution, Luminosity Function and Cosmic Evolution  

CERN Document Server

We infer the normalization and the radial and angular distributions of the number density of satellites of massive galaxies ($\\log_{10}[M_{h}^*/M\\odot]>10.5$) between redshifts 0.1 and 0.8 as a function of host stellar mass, redshift, morphology and satellite luminosity. Exploiting the depth and resolution of the COSMOS HST images, we detect satellites up to eight magnitudes fainter than the host galaxies and as close as 0.3 (1.4) arcseconds (kpc). Describing the number density profile of satellite galaxies to be a projected power law such that $P(R)\\propto R^{\\rpower}$, we find $\\rpower=-1.1\\pm 0.3$. We find no dependency of $\\rpower$ on host stellar mass, redshift, morphology or satellite luminosity. Satellites of early-type hosts have angular distributions that are more flattened than the host light profile and are aligned with its major axis. No significant average alignment is detected for satellites of late-type hosts. The number of satellites within a fixed magnitude contrast from a host galaxy is depe...

Nierenberg, A M; Treu, T; Marshall, P J; Fassnacht, C D; Busha, Michael T

2012-01-01

388

Low Extreme-ultraviolet Luminosities Impinging on Protoplanetary Disks  

Science.gov (United States)

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 ?m 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.

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

2014-11-01

389

The z=5 Quasar Luminosity Function from SDSS Stripe 82  

CERN Document Server

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_1450<-26) with Sloan Digital Sky Survey (SDSS) data covering ~6000 deg^2, then extend to lower luminosities (M_1450<-24) with newly discovered, faint z~5 quasars selected from 235 deg^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 (BOSS), and 59 quasars observed at the MMT and Magellan telescopes. We construct a well-defined sample of 4.7

McGreer, Ian D; Fan, Xiaohui; Richards, Gordon T; Strauss, Michael A; Ross, Nicholas P; White, Martin; Shen, Yue; Schneider, Donald P; Myers, Adam D; Brandt, W Niel; DeGraf, Colin; Glikman, Eilat; Ge, Jian; Streblyanska, Alina

2012-01-01

390

The metric of the cosmos from luminosity and age data  

International Nuclear Information System (INIS)

This paper presents the algorithm for determining the Lemaître-Tolman model that best fits given datasets for maximum stellar ages, and SNIa luminosities, both as functions of redshift. It then applies it to current cosmological data. Special attention must be given to the handling of the origin, and the region of the maximum diameter distances. As with a previous combination of datasets (galaxy number counts and luminosity distances versus redshift), there are relationships that must hold at the region of the maximum diameter distance, which are unlikely to be obeyed exactly by real data. We show how to make corrections that enable a self-consistent solution to be found. We address the questions of the best way to approximate discrete data with smooth functions, and how to estimate the uncertainties of the output — the 3 free functions that determine a specific Lemaître-Tolman metric. While current data does not permit any confidence in our results, we show that the method works well, and reasonable Lemaître-Tolman models do fit with or without a cosmological constant

391

High luminosity electron-hadron collider eRHIC  

Energy Technology Data Exchange (ETDEWEB)

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.

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

392

AGB Variables and the Mira Period-Luminosity Relation  

CERN Document Server

Published data for large amplitude asymptotic giant branch variables in the Large Magellanic Cloud are re-analysed to establish the constants for an infrared (K) period-luminosity relation of the form: Mk=rho[log P-2.38] + delta. A slope of rho=-3.51+/-0.20 and a zero point of delta=-7.15+/-0.06 are found for oxygen-rich Miras (if a distance modulus of 18.39+/-0.05 is used for the LMC). Assuming this slope is applicable to Galactic Miras we discuss the zero-point for these stars using the revised Hipparcos parallaxes together with published VLBI parallaxes for OH Masers and Miras in Globular Clusters. These result in a mean zero-point of delta=-7.25+/-0.07 for O-rich Galactic Miras. The zero-point for Miras in the Galactic Bulge is not significantly different from this value. Carbon-rich stars are also discussed and provide results that are consistent with the above numbers, but with higher uncertainties. Within the uncertainties there is no evidence for a significant difference between the period-luminosity ...

Whitelock, Patricia A; van Leeuwen, Floor

2008-01-01

393

The luminosities of type II Cepheids and RR Lyrae variables  

CERN Document Server

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 than the PL relation. The OGLEIII optical data for the LMC field variables show similar trends. Infrared colours of stars in the RV Tau period range show marked mean differences between three groupings; the Galactic field, the LMC field, and globular clusters. In the case of the Galactic field, at least, this may be strongly influenced by selection effects. In the period range about 4 to 20 days (the W Vir range) there are stars lying above the PL relation which may be recognized by their light curves and are all likely ...

Feast, Michael

2009-01-01

394

Low-luminosity stellar mass functions in globular clusters  

International Nuclear Information System (INIS)

New data are presented on cluster luminosity functions and mass functions for selected fields in the globular clusters M13 and M71, extending down the main sequence to at least 0.2 solar mass. In this experiment, CCD photometry data were obtained at the prime focus of the CFHT on the cluster fields that were far from the cluster center. Luminosity functions were constructed, using the ADDSTAR routine to correct for the background, and mass functions were derived using the available models. The mass functions obtained for M13 and M71 were compared to existing data for NGC 6397. Results show that (1) all three globular clusters display a marked change in slope at about 0.4 solar mass, with the slopes becoming considerably steeper toward lower masses; (2) there is no correlation between the slope of the mass function and metallicity; and (3) the low-mass slope of the mass function for M13 is much steeper than for NGC 6397 and M71. 22 refs

395

SDSS Galaxy Clustering: Luminosity & Color Dependence and Stochasticity  

CERN Document Server

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...

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

2007-01-01

396

An Upgraded ATLAS Central Trigger for 2015 LHC Luminosities  

CERN Document Server

The LHC collides protons at a rate of 40 MHz and each collision produces ?1.5~MB of data from the ATLAS detector. The ATLAS trigger system is implemented in three levels and selects only the most interesting collision events to reduce the event storage rate to about 400 Hz. The first level is implemented in custom electronics and reduces the input rate to ?75 kHz with a decision latency of ?2.5 us. It is also responsible for initiating the read-out of data from all the sub-detectors in ATLAS. Based primarily on information from calorimeters and muon trigger detectors, the Central Trigger Processor (CTP) produces the Level-­1 trigger decision. After a very successful first run, the LHC is now being upgraded to operate with increased luminosity and a center-of-mass energy of up to 14 TeV. To cope with the higher luminosities, the Level-1 trigger system will have to perform a more refined selection in order to not lose interesting physics data while keeping the total Level-1 rate below 100~kHz. In this pr...

Ohm, C; The ATLAS collaboration

2014-01-01

397

HERA+LC based ?p collider: Luminosity and physics  

International Nuclear Information System (INIS)

We discuss the possibility of constructing a Linac-Ring type ep collider and a ?p collider based on it at DESY, namely the HERA+LC proposal. Using the parameters of the proton ring of HERA and those of the proposed linear e+e- collider (LC), we expect a luminosity of L?p=(1-2)x1031 cm-2 s-1 due to reasonable improvement of the proton beam. In a ?p collider, high energy ? beam is produced by the Compton backscattering of laser photons off electron beam from linear accelerator. In the case of opposite choice of laser photon and electron beam helicities, the luminosity of ?p collisions still exceeds 1031 cm-2 s-1 up to a distance of 12 m between the conversion region and the collision point. We examine the physics research program for the HERA+LC ?p collider proposal. Search for the supersymmetric partners, leptoquark production as well as heavy quark investigation are considered in detail. The capacity of HERA+LC surpasses that of HERA and is comparable with LC. Polarization facilities of the gamma and proton beams, and the clearer background compared to the hadron colliders are stated as additional advantages of the proposed ?p collider. (orig.)

398

Biases in the quasar mass-luminosity plane  

Science.gov (United States)

We find that the recently reported departure from the Eddington luminosity limit for the highest quasar black hole masses at a given redshift is an artefact due to biases in black hole mass measurements. This sub-Eddington boundary (with non-unity slope) in the quasar mass-luminosity plane was initially reported by Steinhardt & Elvis using the full width at half-maximum (FWHM) based black hole mass catalogue of Shen et al. However, the significance of the boundary is reduced when the FWHM-based mass scaling relationship is recalibrated following Wang et al. and using the most updated reverberation mapping estimates of black hole masses. Furthermore, this boundary is not seen using mass estimates based on the line dispersion of the same quasars' Mg II emission lines. Thus, the initial report of a sub-Eddington boundary with non-unity slope was due to biases in estimating masses using the FWHM of a fit of one or two Gaussians to quasar Mg II emission lines. We provide evidence that using the line dispersion of the Mg II line produces less biased black hole mass estimates.

Rafiee, Alireza; Hall, Patrick B.

2011-08-01

399

The CLASS BL Lac sample: The Radio Luminosity Function  

CERN Document Server

This paper presents a new sample of BL Lac objects selected from a deep (30 mJy) radio survey of flat spectrum radio sources (the CLASS blazar survey, henceforth CBS). The sample is one of the largest well defined samples in the low power regime with a total of 130 sources of which 55 satisfy the 'classical' optical BL Lac selection criteria, and the rest have indistinguishable radio properties. The primary goal of this study is to establish the Radio Luminosity Function (RLF) on firm statistical ground at low radio luminosities where previous samples have not been able to investigate. The gain of taking a peek at lower powers is the possibility to search for the flattening of the LF which is a feature predicted by the beaming model but which has remained elusive to observational confirmation. In this study we extend for the first time the BL Lac RLF down to very low radio powers ~10^22 W/Hz, ie, two orders of magnitude below the RLF currently available in the literature. In the process we confirm the importa...

Marcha, M J M

2013-01-01

400

Weighing neutrinos using high redshift galaxy luminosity functions  

Science.gov (United States)

Laboratory experiments measuring neutrino oscillations indicate small mass differences between different mass eigenstates of neutrinos. The absolute mass scale is however not determined, with at present the strongest upper limits coming from astronomical observations rather than terrestrial experiments. The presence of massive neutrinos suppresses the growth of perturbations below a characteristic mass scale, thereby leading to a decreased abundance of collapsed dark matter halos. Here we show that this effect can significantly alter the predicted luminosity function (LF) of high redshift galaxies. In particular we demonstrate that a stringent constraint on the neutrino mass can be obtained using the well measured galaxy LF and our semianalytic structure formation models. Combining the constraints from the Wilkinson Microwave Anisotropy Probe 7 yr (WMAP7) data with the LF data at z˜4, we get a limit on the sum of the masses of 3 degenerate neutrinos ?m?different astronomical measurements may suffer from different set of biases, the method presented here provides a complementary probe of ?m?. We suggest that repeating this exercise on well measured luminosity functions over different redshift ranges can provide independent and tighter constraints on ?m?.

Jose, Charles; Samui, Saumyadip; Subramanian, Kandaswamy; Srianand, Raghunathan

2011-06-01

401

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

402

The dynamical state of galaxy groups and their luminosity content  

CERN Document Server

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...

Martinez, Hector J

2011-01-01

403

The Variation of the Galaxy Luminosity Function with Group Properties  

CERN Document Server

We explore the shape of the galaxy luminosity function (LF) in groups of different mass by creating composite LFs over large numbers of groups. Following previous work using total group luminosity as the mass indicator, here we split our groups by multiplicity and by estimated virial (group halo) mass, and consider red (passive) and blue (star forming) galaxies separately. In addition we utilise two different group catalogues (2PIGG and Yang et al.) in order to ascertain the impact of the specific grouping algorithm and further investigate the environmental effects via variations in the LF with position in groups. Our main results are that LFs show a steepening faint end for early type galaxies as a function of group mass/ multiplicity, with a much suppressed trend (evident only in high mass groups) for late type galaxies. Variations between LFs as a function of group mass are robust irrespective of which grouping catalogue is used, and broadly speaking what method for determining group `mass' is used. We fin...

Robotham, Aaron; de Propris, Roberto

2010-01-01

404

HII Region Luminosity Function of the Interacting Galaxy M51  

CERN Document Server

We present a study of HII regions in M51 using the Hubble Space Telescope ACS images taken as part of the Hubble Heritage Program. We have catalogued about 19,600 HII regions in M51 with Ha luminosity in the range of L = 10^{35.5} erg/s to 10^{39.0} erg/s. The Ha luminosity function of HII regions (HII LF) in M51 is well represented by a double power law with its index alpha=-2.25\\pm0.02 for the bright part and alpha=-1.42\\pm0.01 for the faint part, separated at a break point L= 10^{37.1} erg/s. This break was not found in previous studies of M51 HII regions. Comparison with simulated HII LFs suggests that this break is caused by the transition of HII region ionizing sources, from low mass clusters (with ~ 10^3 M_sun, including several OB stars) to more massive clusters (including several tens of OB stars). The HII LFs with L < 10^{37.1} erg/s are found to have different slopes for different parts in M51: the HII LF for the interarm region is steeper than those for the arm and the nuclear regions. This obs...

Lee, Jong Hwan; Lee, Myung Gyoon

2011-01-01

405

The X-ray luminosity function and gas mass function for optically-selected poor plus rich clusters of galaxies  

CERN Document Server

We present the first X-ray Luminosity Function (XLF) for an optically-selected sample of 49 nearby poor clusters of galaxies and a sample of 67 Abell clusters with z < 0.15. We have extended the measured cluster XLF by more than a factor of 10 in X-ray luminosity. Our poor cluster sample was drawn from an optical catalog of groups with 0.01luminosities from (1.7-65)x 10^{41} h^{-2} ergs/sec. These are among the X-ray brightest, optically-selected poor clusters in the northern hemisphere. For this sample, the poor cluster XLF was found to be smooth extrapolation of the rich cluster XLF. A new Hydro/N-body simulation of a Hot +Cold dark matter model with \\Omega_{total}=1, \\Omega_{\

Burns, J O; Loken, C; Klypin, A A; Voges, W; Bryan, G L; Norman, M L; White, A; Burns, Jack O; Ledlow, Michael J; Loken, Chris; Klypin, Anatoly; Voges, Wolfgang; Bryan, Greg L; Norman, Michael L

1996-01-01

406

A Systematic Search for Molecular Outflows Toward Candidate Low-Luminosity Protostars and Very Low Luminosity Objects  

CERN Document Server

We present a systematic single-dish search for molecular outflows toward a sample of 9 candidate low-luminosity protostars and 30 candidate Very Low Luminosity Objects (VeLLOs; L_int < 0.1 L_sun). The sources are identified using data from the Spitzer Space Telescope catalogued by Dunham et al. toward nearby (D < 400 pc) star forming regions. Each object was observed in 12CO and 13CO J = 2-1 simultaneously using the sideband separating ALMA Band-6 prototype receiver on the Heinrich Hertz Telescope at 30 arcsecond resolution. Using 5-point grid maps we identify five new potential outflow candidates and make on-the-fly maps of the regions surrounding sources in the dense cores B59, L1148, L1228, and L1165. Of these new outflow candidates, only the map of B59 shows a candidate blue outflow lobe associated with a source in our survey. We also present larger and more sensitive maps of the previously detected L673-7 and the L1251-A IRS4 outflows and analyze their properties in comparison to other outflows fro...

Schwarz, Kamber R; Dunham, Michael M

2012-01-01

407

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

Science.gov (United States)

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.

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

408

Deriving an X-ray luminosity function of dwarf novae based on parallax measurements  

CERN Document Server

We have derived an X-ray luminosity function using parallax-based distance measurements of a set of 12 dwarf novae, consisting of Suzaku, XMM-Newton and ASCA observations. The shape of the X-ray luminosity function obtained is the most accurate to date, and the luminosities of our sample are concentrated between ~10^{30}-10^{31} erg s^{-1}, lower than previous measurements of X-ray luminosity functions of dwarf novae. Based on the integrated X-ray luminosity function, the sample becomes more incomplete below ~3 x 10^{30} erg s^{-1} than it is above this luminosity limit, and the sample is dominated by X-ray bright dwarf novae. The total integrated luminosity within a radius of 200 pc is 1.48 x 10^{32} erg s^{-1} over the luminosity range of 1 x 10^{28} erg s^{-1} and the maximum luminosity of the sample (1.50 x 10^{32} erg s^{-1}). The total absolute lower limit for the normalised luminosity per solar mass is 1.81 x 10^{26} erg s^{-1} M^{-1}_{solar} which accounts for ~16 per cent of the total X-ray emissivit...

Byckling, Kristiina; Thorstensen, John; Osborne, Julian

2010-01-01

409

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

410

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

411

New ATLAS pixel Front-End chip for upgraded luminosity  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2009-07-01

412

An Upgraded ATLAS Central Trigger for 2015 Luminosities  

CERN Document Server

The Central Trigger Processor (CTP) is the core unit of the first of three levels that constitute the ATLAS trigger system. Based on information from calorimeter and muon trigger processors as well as from some additional systems it produces the level-1 trigger decision and prompts the read-out of the sub-detectors. The increase in luminosity at the LHC has pushed the CTP operation to its design limits. In order to still satisfy the physics goals of the experiment after the shutdown of the LHC of 2013/2014 the CTP will be upgraded during this period. This article discusses the current Central Trigger Processor, the motivation for the upgrade, and the changes foreseen to meet the requirements of the post-2014 physics runs at the LHC.

Poettgen, R; The ATLAS collaboration

2013-01-01

413

On the accretion luminosity of isolated neutron stars  

CERN Document Server

The accretion process onto a magnetized isolated neutron star, which captures material from the interstellar medium, is discussed. The evolutionary track of such a star can be presented as a sequence of four states: ejector, supersonic propeller, subsonic propeller, and steady accretor. I show that subsonic propeller - accretor transition does not occur as long as the magnetic field of the star is strong enough to control the accretion flow in the stellar vicinity. During the subsonic propeller state the accretion rate onto the stellar surface is limited to the rate of plasma diffusion into its magnetosphere. The diffusion rate is at least three orders of magnitude smaller than the maximum possible mass capture rate by the star. Therefore, the expected accretion luminosity of magnetized isolated neutron stars is at least three orders of magnitude smaller than that previously evaluated.

Ikhsanov, N R

2003-01-01

414

Fast Frontend Electronics for high luminosity particle detectors  

CERN Document Server

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...

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

2015-01-01

415

Luminosity distance and redshift in the Szekeres inhomogeneous cosmological models  

International Nuclear Information System (INIS)

The Szekeres inhomogeneous models can be used to model the true lumpy universe that we observe. This family of exact solutions to Einstein's equations was originally derived with a general metric that has no symmetries. In this work, we develop and use a framework to integrate the angular diameter and luminosity distances in the general Szekeres models. We use the affine null geodesic equations in order to derive a set of first-order ordinary differential equations that can be integrated numerically to calculate the partial derivatives of the null vector components. These equations allow the integration in all generality of the distances in the Szekeres models and some examples are given. The redshift is determined from simultaneous integration of the null geodesic equations. This work does not assume spherical or axial symmetry, and the results will be useful for comparisons of the general Szekeres inhomogeneous models to current and future cosmological data

416

Globular Clusters and the Mira Period-Luminosity Relation  

CERN Document Server

A globular cluster distance scale based on Hipparcos parallaxes of subdwarfs has been used to derive estimates of M_K for cluster Miras, including one in the SMC globular cluster NGC121. These lead to a zero-point of the Mira infrared period-luminosity relation, PL(K), in good agreement with that derived from Hipparcos parallaxes of nearby field Miras. The mean of these two estimates together with data on LMC Miras yields an LMC distance modulus of 18.60 +/- 0.10 in evident agreement with a metallicity corrected Cepheid modulus (18.59 +/- 0.10). The use of luminous AGB stars as extragalactic population indicators is also discussed.

Feast, M W; Menzies, J; Feast, Michael; Whitelock, Patricia; Menzies, John

2002-01-01

417

Robust Constraint of Luminosity Function Evolution Through MCMC Sampling  

CERN Document Server

We present a new galaxy survey simulation package, which combines the power of Markov Chain Monte Carlo (MCMC) sampling with a robust and adaptable model of galaxy evolution. The aim of this code is to aid in the characterization and study of new and existing galaxy surveys. In this paper we briefly describe the MCMC implementation and the survey simulation methodology and associated tools. A test case of this full suite was to constrain the evolution of the IR Luminosity Function (LF) based on the HerMES (Herschel SPIRE) survey of the Spitzer First Look Survey field. The initial results are consistent with previous studies, but our more general approach should be of wider benefi?t to the community.

Kurinsky, Noah

2014-01-01

418

Weighing neutrinos using high redshift galaxy luminosity functions  

CERN Document Server

Laboratory experiments measuring neutrino oscillations, indicate small mass differences between different mass eigenstates of neutrinos. The absolute mass scale is however not determined, with at present the strongest upper limits coming from astronomical observations rather than terrestrial experiments. The presence of massive neutrinos suppresses the growth of perturbations below a characteristic mass scale, thereby leading to a decreased abundance of collapsed dark matter halos. Here we show that this effect can significantly alter the predicted luminosity function (LF) of high redshift galaxies. In particular we demonstrate that a stringent constraint on the neutrino mass can be obtained using the well measured galaxy LF and our semi-analytic structure formation models. Combining the constraints from the Wilkinson Microwave Anisotropy Probe 7 year (WMAP7) data with the LF data at z = 4, we get a limit on the sum of the masses of 3 degenerate neutrinos \\Sigma m_\

Jose, Charles; Subramanian, Kandaswamy; Srianand, Raghunathan

2011-01-01

419

CMS in the high luminosity era of the LHC  

CERN Document Server

In this presentation, the presentations and discussions of the workshop are summarized. LHC and CMS progress in physics thus far are covered along with the status of the Higgs and related new physics searches. The absence of new physics in any searches has created some stir in the theoretical community, emphasizing the need for greater input from the experimental side. Lessons for the near term are considered, followed by a look forward to potential future High Luminosity and High Energy eras of operation for the LHC. The potential new physics landscape to be explored remains fairly broad as presented in many talks at the workshop. Properties of a Higgs at 125–126 GeV could be studied in these future periods. In the Higgs sector the key items to be measured are delineated and related back to the needs of CMS upgrades. The opportunities and challenges are both very great.

Incandela, J

2013-01-01

420

The Herschel Virgo Cluster Survey: I. Luminosity functions  

CERN Document Server

We describe the Herschel Virgo Cluster Survey (HeViCS) and the first data obtained as part of the Science Demonstration Phase (SDP). The data cover a central 4x4 sq deg region of the cluster. We use SPIRE and PACS photometry data to produce 100, 160, 250, 350 and 500 micron luminosity functions (LFs) for optically bright galaxies that are selected at 500 micron and detected in all bands. We compare these LFs with those previously derived using IRAS, BLAST and Herschel-ATLAS data. The Virgo Cluster LFs do not have the large numbers of faint galaxies or examples of very luminous galaxies seen previously in surveys covering less dense environments.

Davies, J I; Bendo, G J; Bianchi, S; Bomans, D J; Boselli, A; Clemens, M; Corbelli, E; Cortese, L; Dariush, A; De Looze, I; Alighieri, S di Serego; Fadda, D; Fritz, J; Garcia-Appadoo, D A; Gavazzi, G; Giovanardi, C; Grossi, M; Hughes, T M; Hunt, L K; Jones, A P; Madden, S; Pierini, D; Pohlen, M; Sabatini, S; Smith, M W L; Verstappen, J; Vlahakis, C; Xilouris, E M; Zibetti, S

2010-01-01

421

The low-luminosity J-type carbon stars  

International Nuclear Information System (INIS)

The He shell flash mechanism does not account for the 13C-rich carbon stars (J stars) found on the lower fringe of the luminosity distribution of carbon stars in Magellanic Cloud clusters. Most cluster carbon stars have weak 13C, like most of the N-type carbon stars in the Galaxy. Galactic R stars almost all have enhanced 13C. They have normal abundances of s-process elements, whereas N stars have large overabundances. These differences suggest a real physical distinction in addition to the well-known difference in effective temperature between R and N stars. The colours of carbon stars depend systematically on the spectroscopic group and so cannot easily be used to compare the temperatures of stars in different groups. (author)

422

The Origin of Intermediate-Luminosity Red Transients  

Science.gov (United States)

Intermediate-luminosity red transients (ILRTs) are a new class of optical transients. They have maximum luminosities between novae and SNe, and outbursts lasting several months, becoming cool, dusty, and extremely red as the eruptions proceed. A prototype is V838 Mon, which illuminated a spectacular light echo. Their outbursts may be due to catastrophic stellar collisions and mergers. This is demonstrably true for V1309 Sco, which was a contact binary before its eruption and is now a single star. However, it is not yet clear whether all ILRTs are due to mergers.I propose WFC3 imaging of 3 ILRTs: (1) V4332 Sgr, which erupted in the Galactic bulge in 1994, is now a 19th-mag, very red remnant. Based on a high degree of linear polarization in ground-based measurements, it has been proposed that it is surrounded and obscured by a dusty, edge-on envelope, ejected during a stellar merger. If so, V4332 Sgr ought to display a dark lane at HST imaging resolution. (2) M31 RV is an ILRT that occurred in the bulge of M31 in 1988. HST images of the site taken between 1999 and 2010 failed to reveal a credible remnant of this event. However, models of expanding dusty envelopes predict that eventually, as the optical depth diminishes, the remnant should brighten. The passage of 5 years since the last HST observation of the field justifies another attempt to identify the putative merged binary. (3) CK Vul, the bright "nova" of 1670, is a candidate ILRT because of its red color and an outburst light curve resembling that of V838 Mon. A faint bipolar nebula lies at the site of CK Vul, but no credible remnant star has been found in ground-based images. HST resolution may reveal it.

Bond, Howard

2014-10-01

423

Upgraded Readout Electronics for the ATLAS Liquid Argon Calorimeters at the High Luminosity LHC  

International Nuclear Information System (INIS)

The ATLAS liquid-argon calorimeters produce a total of 182,486 signals which are digitized and processed by the front-end and back-end electronics at every triggered event. In addition, the front-end electronics sum analog signals to provide coarsely grained energy sums, called trigger towers, to the first-level trigger system, which is optimized for nominal LHC luminosities. However, the pile-up background expected during the high luminosity phases of the LHC will be increased by factors of 3 to 7. An improved spatial granularity of the trigger primitives is therefore proposed in order to improve the identification performance for trigger signatures, like electrons or photons, at high background rejection rates. For the first upgrade phase in 2018, new Liquid Argon Trigger Digitizer Boards are being designed to receive higher granularity signals, digitize them on detector and send them via fast optical links to a new, off-detector digital processing system. The digital processing system applies digital filtering and identifies significant energy depositions. The refined trigger primitives are then transmitted to the first level trigger system to extract improved trigger signatures. The general concept of the upgraded liquid-argon calorimeter readout together with the various electronics components to be developed for such a complex system is presented. The research activities and architectural studies undertaken by the ATLAS Liquid Argon Calorimeter Group are describLiquid Argon Calorimeter Group are described, particularly details of the on-going design of mixed-signal front-end electronics, of radiation tolerant optical-links, and of the high-speed off-detector digital processing system.

424

Measurement of the luminosity in the ZEUS experiment at HERA II  

Science.gov (United States)

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.

Adamczyk, L.; Andruszkow, J.; Bold, T.; Borzemski, P.; Buettner, C.; Caldwell, A.; Chwastowski, J.; Daniluk, W.; Drugakov, V.; Eskreys, A.; Figiel, J.; Galas, A.; Gil, M.; Helbich, M.; Januschek, F.; Jurkiewicz, P.; Kisielewska, D.; Klein, U.; Kotarba, A.; Lohmann, W.; Ning, Y.; Oliwa, K.; Olkiewicz, K.; Paganis, S.; Pieron, J.; Przybycien, M.; Ren, Z.; Ruchlewicz, W.; Schmidke, W.; Schneekloth, U.; Sciulli, F.; Stopa, P.; Sztuk-Dambietz, J.; Suszycki, L.; Sutiak, J.; Wierba, W.; Zawiejski, L.

2014-04-01

425

A reexamination of luminosity sources in T Tauri stars. I. Taurus-Auriga  

International Nuclear Information System (INIS)

An analysis is presented of 72 T Tau stars identified by IRAS in the Tau-Aur complex. The composite energy distributions of the stars are constructed to define bolometric luminosities and the luminosity components in different spectral regimes are separated. The near- to far-IR spectral indices of these stars are analyzed. It is shown that 2/3 of typical T Tau stars have a bolometric to stellar luminosity ratio of about 1.0, which implies no appreciable disks. The distribution is bimodal, however, with a second peak at about 2.0, suggesting that 1/3 of the stars have disks. The bolometric luminosities of the north and south components of T Tau are found to be in the range of 9-21 solar luminosities and 1.5-14 solar luminosities for T Tau N and T Tau S, respectively. 56 refs

426

The D0 luminosity monitor constant for ? s = 630 GeV  

International Nuclear Information System (INIS)

D0 has calculated the luminosity monitor constant for ?s= 630 GeV. The inelastic p anti p cross section was interpolated between measurements performed at ?s = 546 and 1800 GeV. The geometric acceptance, hardware efficiency, and luminosity-dependent corrections are similar to those previously published for the full Tevatron energy. We find a luminosity-weighted value of ?L0 = 34.04 ± 1.05 mb, yielding a precision of ± 3.08%

427

On the Origin of the Type Ia Supernova Width-Luminosity Relation  

OpenAIRE

Brighter Type Ia supernovae (SNe Ia) have broader, more slowly declining B-band light curves than dimmer SNe Ia. We study the physical origin of this width-luminosity relation (WLR) using detailed radiative transfer calculations of Chandrasekhar mass SN Ia models. We find that the luminosity dependence of the diffusion time (emphasized in previous studies) is in fact of secondary relevance in understanding the model WLR. Instead, the essential physics involves the luminosity...

Kasen, Daniel; Woosley, S. E.

2006-01-01

428

Ages of globular clusters: breaking the age-distance degeneracy with the luminosity function  

OpenAIRE

We extend our previous method to determine globular cluster ages using the luminosity function (Jimenez \\& Padoan 1996). We show that the luminosity function depends on both age and distance modulus and that it is possible to distinguish between the two. This method provides at the same time independent determinations of distance and age of a GC by simply counting the number of stars found inside specified luminosity bins. The main uncertainties in other traditional methods ...

Padoan, Paolo; Jimenez, Raul

1996-01-01

429

Effects of Age and Metallicity on the RGB and AGB Luminosity  

Science.gov (United States)

We look into the RGB and AGB luminosity as a function of age and metallicity of stellar populations. We also investigate the similarities and differences of RGB and AGB luminosity from several different isochrones and stellar evolutionary tracks. The outcome is of paramount importance in order to get the precise distance of galaxies using either the RGB tip luminosity or the Surface Brightness Fluctuation. We will present the uncertainties of distance measurements to the galaxies because of the significant disparities of RGB and AGB luminosity from several different isochrones and stellar evolutionary tracks.

Lee, Hyun-chul; Cartwright, Charles

2015-01-01

430

Luminosities of H alpha emitting regions in a pair of interacting galaxies in the Bootes void  

Science.gov (United States)

Luminosities of H alpha emission from a pair of interacting galaxies in the low density environment of the Bootes void are presented. CG 692 (IRAS 1519+5050) has an H alpha luminosity of 2 x 10(exp 42) ergs s(exp -1), indicating a star formation rate of 18.4 solar mass yr(exp -1). Individual extranuclear H alpha regions have luminosities of approximately 10(exp 40) ergs s(exp -1). These luminosities are similar to those found for H II regions in bright, late-type galaxies in more densely populated parts of the Universe.

Weistrop, D.; Hintzen, P.; Kennicutt, R.; Liu, C.; Lowenthal, J.; Cheng, K.-P.; Oliversen, R.; Woodgate, B.

1993-01-01

431

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

CERN Document Server

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.

Esberg, Jakob; Uggerhoj, Ulrik; Dalena, Barbara

2011-01-01

432

A non-parametric analysis of the luminosity function of cluster galaxies.  

Science.gov (United States)

Photographic F band photometry of a sample of 36 Abell clusters, has been used to study possible systematic differences between the luminosity functions of galaxies belonging to clusters of different Rood & Sastry type. A Kolmogorov-Smirnov two-sample test shows that the average luminosity functions of clusters of various type differ in a statistically significant way. In particular core and linear clusters appear intermediate between cD and flat or irregular clusters. The results appear consistent with the cannibalism model, where the luminosity function evolves through a merging process which affects preferentially the bright end of their luminosity function.

Trèvese, D.; Appodia, B.; Cenci, A.; Cirimele, G.

1996-02-01

433

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 luminosityeak, 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.

434

On the luminosity distance and the epoch of acceleration  

Science.gov (United States)

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 ?? 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 ? 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.

Sutherland, Will; Rothnie, Paul

2015-02-01

435

Calibration of Gamma-Ray Burst Luminosity Indicators  

CERN Document Server

Several gamma-ray burst (GRB) luminosity indicators (LIs)have been proposed. Unlike SNe Ia, calibration of GRB LIs using a low-redshift sample is difficult. Based on the Bayesian theory, here we propose an approach to calibrate these LIs without introducing a low-redshift GRB sample. The essential points of our approach include, (1) calibrate the power-law indices in the LIs with a sample of GRBs in a narrow redshift range (Delta z); and (2) marginalize the coefficient of the LIs over a reasonable range of cosmological parameters. We take our newly discovered multivariable GRB LIs as an example and test the validity of our approach through simulations. We show that while the coefficient strongly depends on the cosmological parameters, the power-law indices do not as long as Delta z is small enough. The selection of Delta z for a particular GRB sample could be judged according to the size and the observational uncertainty of the sample. There is no preferable redshift to perform the calibration of the indices,...

Liang, E; Liang, Enwei; Zhang, Bing

2005-01-01

436

The Fast Tracker Architecture for the LHC baseline luminosity  

CERN Document Server

Hadron collider experiments search for extremely rare processes hidden in much higher background levels. Only a tiny fraction of the produced collisions can be stored on tape and an enormous real-time data reduction is needed. This requires massive computing power to minimize the on-line execution time of complex algorithms. A multi-level trigger is an effective solution for an otherwise impossible problem. The Fast Tracker (FTK) [1, 2] has been proposed for high quality track finding at very high rates (Level-1 output rates) for the ATLAS experiment. FTK will use FPGA and ASIC devices in order to complement CPUs. FTK beats the combinatorial challenge with special associative memories, where parallelism is exploited to the maximum level. The associative memories compare the track detector hits to all pre-calculated track patterns at once. The system design is defined and proposed for high-luminosity studies including low-PT Bphysics and high-PT signatures for Level-2 selections: b-jets, tau-jets, and isolated...

Annovi, A.

2009-01-01

437

The Luminosity Function of Low-Redshift Abell Galaxy Clusters  

CERN Document Server

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...

Barkhouse, Wayne A; López-Cruz, Omar

2007-01-01

438

An Anthropology of Luminosity : the Agency of Light  

DEFF Research Database (Denmark)

This article addresses the relationship between light, material culture and social experiences. It argues that understanding light as a powerful social agent, in its relationship with people, things, colours, shininess and places, may facilitate an appreciation of the active social role of 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 studies it is argued that light may be used as a tool for exercising social intimacy and inclusion, of shaping moral spaces and hospitality, and orchestrating movement, while working as a metaphor as well as a material agent in these social negotiations. The social comprehension of light is a means of understanding social positions in ways that may be real or imagined, but are bound up on the social and cultural associations of certain lightscapes

Bille, Mikkel; SØrensen, Tim Flohr

2007-01-01

439

The winds of high luminosity late-type bright stars  

Science.gov (United States)

The occurrence and characteristics of the Fe II line asymmetries were studied to determine the radial dependence of the wind velocity for each star. The dependence of the Fe II profiles on spectral type and luminosity class and thus the variation of the velocity fields with stellar type was also investigated. This allows the generality of the results reported for alpha Ori by Carpenter (1984b) to be judged. In addition, new atomic data was used along with observations of the C II (UV 0.01) multiplet to estimate N(sub e) in the stellar winds. Measures of relative Fe II fluxes can be used in a probability-of-escape model to determine the opacity and hydrogen column density versus height in the chromosphere of each star. Finally, analysis of the fluorescent Fe II lines (pumped by Ly alpha) near 2507 A will yield estimates of the intrinsic stellar Ly alpha flux that cannot be measured directly because of interstellar and circumstellar absorption. One important goal of the effort was to acquire high resolution spectra of the whole 2300 to 3200 A region of 13 luminous K and M stars as a data base that will be enormously valuable in planning observations with the Hubble Space Telescope High Resolution Spectrograph. It is also proposed to follow up the recent discovery of significant variations in the Fe II chromospheric emission line profiles from the M-giant Gamma Cru for the purpose of determining the underlying cause of the variations.

Stencel, Robert E.; Carpenter, K. G.

1989-01-01

440

Bias in the Estimation of Global Luminosity Functions  

CERN Document Server

We discuss a bias present in the calculation of the global luminosity function (LF) which occurs when analysing faint galaxy samples. This effect exists because of the different spectral energy distributions of galaxies, which are in turn quantified by the k-corrections. We demonstrate that this bias occurs because not all galaxy types are visible in the same absolute magnitude range at a given redshift and it mainly arises at high redshift since it is related to large k-corrections. We use realistic simulations with observed LFs to investigate the amplitude of the bias. We also compare our results to the global LFs derived from Hubble Deep Field-North and -South (HDF) surveys. We conclude that, as expected, there is no bias in the global LF measured in the absolute magnitude range where all galaxy types are observable. Beyond this range the faint-end slope of the global LF can be over/under-estimated depending on the adopted LF estimator. The effect is larger when the reference filter in which the global LF ...

Ilbert, O; Arnouts, S; Zucca, E; Bardelli, S; Zamorani, G; Adami, C; Cappi, A; Garilli, B; Lefèvre, O; MacCagni, D; Meneux, B; Scaramella, R; Scodeggio, M; Vettolani, G; Zanichelli, A

2004-01-01

441

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 s in smaller volumes mostly offset the improved variance gained from independent samples.

442

Period-Luminosity Relation for Type II Cepheids  

CERN Document Server

We have estimated JHKs magnitudes corrected to mean intensity for LMC type II Cepheids found in the OGLE-III survey. Period-luminosity relations (PLRs) are derived in JHKs as well as in a reddening-free VI parameter. The BL Her stars (P<4d) and the W Vir stars (P=4 to 20d) are co-linear in these PLRs. The slopes of the infrared relations agree with those found previously for type II Cepheids in globular clusters within the uncertainties. Using the pulsation parallaxes of V553 Cen and SW Tau, the data lead to an LMC modulus of 18.46+-0.10 mag, uncorrected for any metallicity effects. We have now established the PLR of type II Cepheids as a distance indicator by confirming that (almost) the same PLR satisfies the distributions in the PL diagram of type II Cepheids in (at least) two different systems, i.e. the LMC and Galactic globular clusters, and by calibrating the zero point of the PLR. RV Tau stars in the LMC, as a group, are not co-linear with the shorter-period type II Cepheids in the infrared PLRs in ...

Matsunaga, Noriyuki; Menzies, John W

2009-01-01

443

Tevatron energy and luminosity upgrades beyond the Main Injector  

International Nuclear Information System (INIS)

The Fermilab Tevatron will be the world's highest energy hadron collider until the LHC is commissioned, it has the world's highest energy fixed target beams, and Fermilab will be the leading high energy physics laboratory in the US for the foreseeable future. Following the demise of the SSC, a number of possible upgrades to the Tevatron complex, beyond construction of the Main Injector, are being discussed. Using existing technology, it appears possible to increase the luminosity of the bar pp Collider to at least 1033cm-2sec-1 (Tevatron-Star) and to increase the beam energy to 2 TeV (DiTevatron). Fixed target beam of energy about 1.5 TeV could also be delivered. Leaving the existing Tevatron in the tunnel and constructing bypasses around the collider halls would allow simultaneous 800 GeV fixed target and ?s = 4 TeV collider operation. These upgrades would give Fermilab an exciting physics program which would be complementary to the LHC, and they would lay the groundwork for the construction of a possible post-LHC ultra-high energy hadron collider

444

Jet and disk luminosities in tidal disruption events  

CERN Document Server

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 ...

Piran, Tsvi; Tchekhovskoy, Alexander

2015-01-01

445

On the perturbation of the luminosity distance by peculiar motions  

CERN Document Server

We consider some aspects of the perturbation to the luminosity distance $d(z)$ that are of relevance for SN1a cosmology and for future peculiar velocity surveys at non-negligible redshifts. 1) Previous work has shown that the correction to the lowest order perturbation $\\delta d / d = -\\delta v / c z$ has the peculiar characteristic that it appears to depend on the absolute state of motion of sources, rather than on their motion relative to that of the observer. The resolution of this apparent violation of the equivalence principle is that it is necessary to allow for evolution of the velocities with time, and also, when considering perturbations on the scale of the observer-source separation, to include the gravitational redshift effect. We provide an expression for $\\delta d / d$ that provides a physically consistent way to compute the impact of peculiar motions for SN1a cosmology and peculiar velocity surveys. 2) We then calculate the perturbation to the redshift as a function of source flux density, which...

Kaiser, Nick

2014-01-01

446

Luminosity Function of The Galaxy Cluster Abell 85  

Science.gov (United States)

Using the photometric and spectroscopic data from the NASA/IPAC Extragalactic Database (NED) and the Eighth Data Release of Sloan Digital Sky Survey (SDSS-DR8), we have studied the luminosity function (LF) of the galaxy cluster Abell 85 within the double dynamical radius 2r200. It is shown that the LF of Abell 85 can be fitted very well with a Schechter function in all the 5 SDSS wavebands, and that the LF exhibits a dip in the u, g, and z bands, respectively. The best-fitting parameters (the characteristic absolute magnitude in the r band and the slope at the faint end of the LF) of the Schechter function are ? mag, and ? for the early-type galaxies, ? mag, and ? for the late-type galaxies, respectively. The LF of early-type galaxies shows a dip at ? mag. In addition, we have also investigated the LFs in the three concentric annuli within 1.5r200, and found that the closer the distance from the cluster center, the steeper the faint-end slope, and the brighter the characteristic magnitude.

Li, Feng; Yan, Peng-fei; Yuan, Qi-rong

2014-07-01

447

MULTI-WAVELENGTH CHARACTERISTICS OF PERIOD-LUMINOSITY RELATIONS  

International Nuclear Information System (INIS)

We present a physically motivated explanation for the observed, monotonic increase in slope, and the simultaneous (and also monotonic) decrease in the width/scatter of the Leavitt law (the Cepheid period-luminosity (PL) relation) as one systematically moves from the blue and visual into the near- and mid-infrared. We calibrate the wavelength-dependent, surface-brightness sensitivities to temperature using the observed slopes of PL relations from the optical through the mid-infrared and test the calibration by comparing the theoretical predictions with direct observations of the wavelength dependence of the scatter in the Large Magellanic Cloud Cepheid PL relation. In doing so we find the slope of the period-radius (PR) relation is c = 0.724 ± 0.006. Investigating the effect of differential reddening suggests that this value may be overestimated by as much as 10%; however, the same slope of the PR relation fits the (very much unreddened) Cepheids in IC 1613, albeit with lower precision. The discussion given is general and also applies to RR Lyrae stars, which also show similarly increasing PL slopes and decreasing scatter with increasing wavelength.

448

CONCERNING THE SLOPE OF THE CEPHEID PERIOD-LUMINOSITY RELATION  

International Nuclear Information System (INIS)

We discuss the impact of possible differences in the slope of the Cepheid period-luminosity (PL) relation on the determination of extragalactic distances in the context of recent studies that suggest changes in this slope. We show that the Wesenheit function W = V - R x (V - I), widely used for the determination of the Cepheid distances, is expected to be highly insensitive to changes in the slope of the underlying (monochromatic) PL relations. This occurs because the reddening trajectories in the color-magnitude plane are closely parallel to lines of constant period. As a result W-based PL relations have extremely low-residual dispersion, which is because differential (and the total line of sight) reddening is eliminated in the definition of W and the residual scatter due to a star's intrinsic color/position within the Cepheid is also largely insensitive to W. Basic equations are presented and graphically illustrated, showing the insensitivity of W to changes in the monochromatic PL relations.

449

Deprojection of luminosity functions of galaxies in the Coma cluster  

CERN Document Server

We use a simple analytic model to deproject 2-d luminosity functions (LF) of galaxies in the Coma cluster measured by Beijersbergen et al. 2002. We demonstrate that the shapes of the LFs change after deprojection. It is therefore essential to correct LFs for projection effects. The deprojected LFs of the central area have best-fitting Schechter parameters of M^{*}_U=-18.31^{+0.08}_{-0.08} and \\alpha_U=-1.27^{+0.018}_{-0.018}, M^{*}_B=-19.79^{+0.14}_{-0.15} and \\alpha_B=-1.44^{+0.016}_{-0.016} and M^{*}_r=-21.77^{+0.20}_{-0.28} and \\alpha_r=-1.27^{+0.012}_{-0.012}. The corrections are not significant enough to change the previously observed trend of increasing faint end slopes with increasing distance to the cluster center. The weighted U, B, and r band slopes of the deprojected LFs show a slightly weaker steepening with increasing projected cluster radius.

Beijersbergen, M; Van der Hulst, J M

2002-01-01

450

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

CERN Document Server

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 &...

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

451

Host galaxies of bright high redshift quasars: Luminosities and colours  

CERN Document Server

We present the results of a near-infrared imaging study of high redshift (z~3) quasars using the ESO-VLT. Our targets were selected to have luminosities among the highest known (absolute magnitude M_B <~ -28. We searched for resolved structures underlying the bright point-source nuclei by comparing the QSO images with stars located in the same fields. Two QSOs (HE2348-1444 at z=2.904 and HE2355-5457 at z=2.933) are clearly resolved in K_S, and with somewhat lower significance also in H; one object is resolved only in K_S. At these redshifts, H and K_S correspond almost exactlly to rest-frame B and V, respectively, with virtually no K-correction. We also report briefly the non-detection of some additional QSOs. The detected host galaxies are extremely luminous with M_V ~ -25. Their rest-frame B-V colours, however, are close to zero in the Vega system, indicating substantial contributions from young stars and a stellar mass-to-light ratio below 1 (in solar units). Tentatively converting M_V and B-V into roug...

Schramm, M; Jahnke, K

2007-01-01

452

THE DISK EVAPORATION MODEL FOR THE SPECTRAL FEATURES OF LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI  

International Nuclear Information System (INIS)

Observations show that the accretion flows in low-luminosity active galactic nuclei probably have a two-component structure with an inner, hot, optically thin, advection-dominated accretion flow (ADAF) and an outer, truncated, cool, optically thick accretion disk. As shown by Taam et al., the truncation radius as a function of mass accretion rate is strongly affected by including the magnetic field within the framework of disk evaporation model, i.e., an increase in the magnetic field results in a smaller truncation radius of the accretion disk. In this work, we calculate the emergent spectrum of an inner ADAF + an outer truncated accretion disk around a supermassive black hole based on the prediction by Taam et al.. It is found that an increase in the magnetic field from ? = 0.8 to ? = 0.5 (with magnetic pressure pm = B 2/8? = (1 – ?)ptot, ptot = pgas + pm) results in a factor of ?8.7 increase in the luminosity from the truncated accretion disk. Meanwhile, results of the peak emission of the truncated accretion disk shift toward a a factor of ?5 higher frequency. We found that the equipartition of gas pressure to magnetic pressure, i.e., ? = 0.5, failed to explain the observed anti-correlation between L2-10keV/LEdd and the bolometric correction ?2-10keV (with ?2-10keV = Lbol/L2-10keV). The emergent spectra for larger values of ? = 0.8 or ? = 0.95 can explain the observed L2-10keV/LEdd-?2-10keV correlation. We argue that in the disk evaporation model, the electrons in the corona are assumed to be heated only by a transfer of energy from the ions to electrons via Coulomb collisions, which is reasonable for accretion with a lower mass accretion rate. Coulomb heating is the dominated heating mechanism for the electrons only if the magnetic field is strongly sub-equipartition, which is roughly consistent with observations

453

THE DISK EVAPORATION MODEL FOR THE SPECTRAL FEATURES OF LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI  

Energy Technology Data Exchange (ETDEWEB)

Observations show that the accretion flows in low-luminosity active galactic nuclei probably have a two-component structure with an inner, hot, optically thin, advection-dominated accretion flow (ADAF) and an outer, truncated, cool, optically thick accretion disk. As shown by Taam et al., the truncation radius as a function of mass accretion rate is strongly affected by including the magnetic field within the framework of disk evaporation model, i.e., an increase in the magnetic field results in a smaller truncation radius of the accretion disk. In this work, we calculate the emergent spectrum of an inner ADAF + an outer truncated accretion disk around a supermassive black hole based on the prediction by Taam et al.. It is found that an increase in the magnetic field from ? = 0.8 to ? = 0.5 (with magnetic pressure p{sub m} = B {sup 2}/8? = (1 – ?)p{sub tot}, p{sub tot} = p{sub gas} + p{sub m}) results in a factor of ?8.7 increase in the luminosity from the truncated accretion disk. Meanwhile, results of the peak emission of the truncated accretion disk shift toward a a factor of ?5 higher frequency. We found that the equipartition of gas pressure to magnetic pressure, i.e., ? = 0.5, failed to explain the observed anti-correlation between L{sub 2-10{sub keV}}/L{sub Edd} and the bolometric correction ?{sub 2-10{sub keV}} (with ?{sub 2-10{sub keV}} = L{sub bol}/L{sub 2-10{sub keV}}). The emergent spectra for larger values of ? = 0.8 or ? = 0.95 can explain the observed L{sub 2-10{sub keV}}/L{sub Edd}-?{sub 2-10{sub keV}} correlation. We argue that in the disk evaporation model, the electrons in the corona are assumed to be heated only by a transfer of energy from the ions to electrons via Coulomb collisions, which is reasonable for accretion with a lower mass accretion rate. Coulomb heating is the dominated heating mechanism for the electrons only if the magnetic field is strongly sub-equipartition, which is roughly consistent with observations.

Qiao, Erlin; Liu, B. F. [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Panessa, Francesca [INAF-Istituto di Astrofisica e Planetologia Spaziali di Roma (IAPS), Via del Fosso del Cavaliere 100, I-00133 Roma (Italy); Liu, J. Y., E-mail: qiaoel@nao.cas.cn [Yunnan Observatories, Chinese Academy of Sciences, P.O. Box 110, Kunming 650011 (China)

2013-11-10

454

BSM prospects at the high-luminosity LHC with the ATLAS detector  

CERN Document Server

Prospects for the detection of physics beyond the Standard Model at the high-luminosity LHC with an upgraded ATLAS detector are presented. Both supersymmetric and exotic signals are considered, and limit prospects are compared to those obtained with lower integrated luminosity as well as current 8 TeV limits.

Bugge, M K; The ATLAS collaboration

2014-01-01

455

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

456

Bunch-by-bunch analysis of the LHC heavy-ion luminosity and potential future upgrades  

International Nuclear Information System (INIS)

The lead-ion bunches in the LHC are strongly influenced by intra-beam scattering, especially on the injection plateau of the LHC and even more of the SPS. In combination with the different times the bunches spend at each injection plateau, this results in a spread of the luminosity produced in each bunch crossing. The particle losses during collisions are dominated by nuclear electromagnetic processes, leading to a non-exponential intensity decay during the fill and short luminosity lifetime. The beam and luminosity evolution of the 2011 run was analysed bunch-by-bunch and compared with simulations. Based on this analysis, estimates of the potential luminosity performance at 6.5 Z TeV, after the present shutdown, and options to increase the luminosity are discussed.

457

An investigation of X-ray luminosity versus crystalline powder granularity  

International Nuclear Information System (INIS)

At the High-Throughput Discovery of Scintillator Materials Facility at Lawrence Berkeley National Laboratory, scintillators are synthesized by solid-state reaction or melt mixing, forming crystalline powders. These powders are formed in various granularity and the crystal grain size affects the apparent luminosity of the scintillator. To accurately predict a “full-size” scintillator's crystal luminosity, the crystal luminosity as a function of crystal granularity size has to be known. In this study, we examine Bi4Ge3O12 (BGO), Lu2SiO5:Ce3+ (LSO), YAlO3:Ce3+(YAP:Ce), and CsBa2I5:Eu2+ (CBI) luminosities as a function of crystalline grain size. The highest luminosities were measured for 600- to 1000-?m crystal grain sizes for BGO and LSO, for 310- to 600-?m crystal grain sizes for CBI, and for crystal grains larger than 165 ?m for YAP:Ce. Crystal grains that were larger than 1 mm had a lower packing fraction, and smaller grains were affected by internal scattering. We measured a 34% decrease in luminosity for BGO when decreasing from the 600- to 1000-?m crystal grain size range down to the 20- to 36-?m range. The corresponding luminosity decrease for LSO was 44% for the same grain size decrease. YAP:Ce exhibited a luminosity decrease of 47% when the grain size decreased from the 165- to 310-?m crystal grains to the 20- to 36-?m range, and CB the 20- to 36-?m range, and CBI exhibited a luminosity decrease of 98% when the grain size decreased from the 310- to 600-?m crystal grain range to the 36- to 50-?m range. We were able to very accurately estimate full-size crystal luminosities from crystalline grains that are larger than 90 ?m.

458

STATE TRANSITIONS IN BRIGHT GALACTIC X-RAY BINARIES: LUMINOSITIES SPAN BY TWO ORDERS OF MAGNITUDE  

International Nuclear Information System (INIS)

Using X-ray monitoring observations with the All-Sky Monitor on board the Rossi X-Ray Timing Explorer and the Burst Alert Telescope on board the Swift, we are able to study the spectral state transitions occurred in about 20 bright persistent and transient black hole and neutron star binaries. We have confirmed that there is a correlation between the X-ray luminosity corresponding to the hard-to-soft transition and the X-ray luminosity of the following soft state. This correlation holds over a luminosity range spanning by 2 orders of magnitude, with no indication of a flux saturation or cutoff. We have also found that the transition luminosity correlates with the rate of increase in the X-ray luminosity during the rising phase of an outburst or flare, implying that the origin of the variation of the transition luminosity is associated with non-stationary accretion in both transient sources and persistent sources. The correlation between the luminosity corresponding to the end of the soft-to-hard transition and the peak luminosity of the preceding soft state is found insignificant. The results suggest that the hysteresis effect of spectral state transitions is primarily driven by non-stationary accretion when the mass accretion rate increases rather than the mass accretion rate decreases. Our results also imply that Galactic X-ray binaries can reach more luminous hard states during outbursts of higher luminosities and of similar rise timescales as those observed. Basedr rise timescales as those observed. Based on the correlations, we speculate that bright hard state beyond the Eddington luminosity will be observed in Galactic binaries in the next century. We also suggest that some ultra-luminous X-ray sources in nearby galaxies, which stay in the hard states during bright, short flares, harbor stellar-mass compact stars.

459

SuperB: a Linear High-Luminosity B Factory  

Energy Technology Data Exchange (ETDEWEB)

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.

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

460

Beam dynamics issues of high-luminosity asymmetric collider rings  

International Nuclear Information System (INIS)

Machines for use in high-energy physics are advancing along two frontiers. First, there is the frontier of energy, currently being pressed by the Fermilab collider (p bar p), and SLC and LEP (e+e-) and in the near future by HERA (ep), the LHC, and the SSC (pp). Second, there is the frontier of intensity, currently being pressed by a variety of low-energy machines and, at higher energies, by various linacs such as those at KEK. Fermilab, GSI, and LAMPF (p) and CEBAF (e-). In the future there should be, along this frontier, various ''factories'' such as those for Kaons at TRIUMF, and those proposed for var-phi mesons, ?-charm particles, and B mesons. It is with the intensity frontier that these proceedings are concerned. The elementary particle motivation to study the nonconservation of PC in the B-stringB system (which topic is not covered in these Proceedings, but is treated extensively in the literature) has motivated the study of very high intensity asymmetric collider rings. It was for this purpose that a Workshop on Beam Dynamics Issues of High-Luminosity Asymmetric Collider Rings was held, in Berkeley, during February 12--16, 1990. A general introduction to the subject has been given in an article which is reprinted here as an Appendix. The nonexpert may wish to start there. The volume consists of four parts. The first part consists of Summaries; first an overall summary of the Workshop and then, second, more detailed summaries fd then, second, more detailed summaries from each of the working groups. The second part consists of the Invited Talks at the workshop. The third part contains various Contributed Papers, most of which represent work that came out of the workshop. Finally, there are, in the fourth part, brief Summaries of the Various Proposed B-Factory Projects in the world