2,381 research outputs found

    Relieving tensions related to the lensing of CMB temperature power spectra

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    The angular power spectra of the cosmic microwave background (CMB) temperature anisotropies reconstructed from Planck data seem to present too much gravitational lensing distortion. This is quantified by the control parameter ALA_L that should be compatible with unity for a standard cosmology. With the Class Boltzmann solver and the profile-likelihood method, for this parameter we measure a 2.6σ\sigma shift from 1 using the Planck public likelihoods. We show that, owing to strong correlations with the reionization optical depth τ\tau and the primordial perturbation amplitude AsA_s, a 2σ\sim2\sigma tension on τ\tau also appears between the results obtained with the low (30\ell\leq 30) and high (30<250030<\ell\lesssim 2500) multipoles likelihoods. With Hillipop, another high-\ell likelihood built from Planck data, this difference is lowered to 1.3σ1.3\sigma. In this case, the ALA_L value is still in disagreement with unity by 2.2σ2.2\sigma, suggesting a non-trivial effect of the correlations between cosmological and nuisance parameters. To better constrain the nuisance foregrounds parameters, we include the very high \ell measurements of the Atacama Cosmology Telescope (ACT) and South Pole Telescope (SPT) experiments and obtain AL=1.03±0.08A_L = 1.03 \pm 0.08. The Hillipop+ACT+SPT likelihood estimate of the optical depth is τ=0.052±0.035,\tau=0.052\pm{0.035,} which is now fully compatible with the low \ell likelihood determination. After showing the robustness of our results with various combinations, we investigate the reasons for this improvement that results from a better determination of the whole set of foregrounds parameters. We finally provide estimates of the Λ\LambdaCDM parameters with our combined CMB data likelihood.Comment: accepted by A&

    Agnostic cosmology in the CAMEL framework

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    Cosmological parameter estimation is traditionally performed in the Bayesian context. By adopting an "agnostic" statistical point of view, we show the interest of confronting the Bayesian results to a frequentist approach based on profile-likelihoods. To this purpose, we have developed the Cosmological Analysis with a Minuit Exploration of the Likelihood ("CAMEL") software. Written from scratch in pure C++, emphasis was put in building a clean and carefully-designed project where new data and/or cosmological computations can be easily included. CAMEL incorporates the latest cosmological likelihoods and gives access from the very same input file to several estimation methods: (i) A high quality Maximum Likelihood Estimate (a.k.a "best fit") using MINUIT ; (ii) profile likelihoods, (iii) a new implementation of an Adaptive Metropolis MCMC algorithm that relieves the burden of reconstructing the proposal distribution. We present here those various statistical techniques and roll out a full use-case that can then used as a tutorial. We revisit the Λ\LambdaCDM parameters determination with the latest Planck data and give results with both methodologies. Furthermore, by comparing the Bayesian and frequentist approaches, we discuss a "likelihood volume effect" that affects the optical reionization depth when analyzing the high multipoles part of the Planck data. The software, used in several Planck data analyzes, is available from http://camel.in2p3.fr. Using it does not require advanced C++ skills.Comment: Typeset in Authorea. Online version available at: https://www.authorea.com/users/90225/articles/104431/_show_articl

    Semiconductor resonator solitons above band gap

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    We show experimentally the existence of bright and dark spatial solitons in semiconductor resonators for excitation above the band gap energy. These solitons can be switched on, both spontaneously and with address pulses, without the thermal delay found for solitons below the band gap which is unfavorable for applications. The differences between soliton properties above and below gap energy are discussed.Comment: 4 pages, 7 figure

    Whalesong

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    Vice chancellor speaks out: Beeton reviews year at university -- APEA employees nearly walk out -- Opinion -- Physical education facility planned for area near UAJ student housing -- Campus update -- Chess club holds tourneys -- Classified -- Arts -- The sports page: Ostling overall ski champ at Alyeska Ski Area -- Student government....: News and views from the United Students of UAJ -- F.Y.I. -- Suicide: a crisis of emotion -- Tel-med a free service for student

    Benchmarking Technical and Cost Factors in Forest Felling and Processing Operations in Different Global Regions during the Period 2013-2014

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    In a global bioeconomy, benchmarking costs is essential in the evaluation of current forest harvesting systems and addressing decisions on the most efficient supply chains for available forest resources. Benchmarking cost rates in forestry is challenging, due to a lack of harmonized terminology and difficulties in collecting information on comparable forest technologies. This study provides a first-time series of cost factors to be used when modeling and evaluating the cost competitiveness of forest felling and processing operations on a global scale. It is based on an expert survey using a standardized method of data collection. This benchmarking identifies and updates the knowledge of technical and socio-economic factors capable of influencing the cost rates of forest felling and processing operations across different regions. This study is expected to act as a reference for larger investigations, and for regular updates, with the aim to provide current data that can be used by forest practitioners and decision makers for improving their cost efficiency and for designing future supply systems more effectively

    Patterns and localized structures in bistable semiconductor resonators

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    We report experiments on spatial switching dynamics and steady state structures of passive nonlinear semiconductor resonators of large Fresnel number. Extended patterns and switching front dynamics are observed and investigated. Evidence of localization of structures is given.Comment: 5 pages with 9 figure

    Muon Energy Estimate Through Multiple Scattering with the Macro Detector

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    Muon energy measurement represents an important issue for any experiment addressing neutrino induced upgoing muon studies. Since the neutrino oscillation probability depends on the neutrino energy, a measurement of the muon energy adds an important piece of information concerning the neutrino system. We show in this paper how the MACRO limited streamer tube system can be operated in drift mode by using the TDC's included in the QTPs, an electronics designed for magnetic monopole search. An improvement of the space resolution is obtained, through an analysis of the multiple scattering of muon tracks as they pass through our detector. This information can be used further to obtain an estimate of the energy of muons crossing the detector. Here we present the results of two dedicated tests, performed at CERN PS-T9 and SPS-X7 beam lines, to provide a full check of the electronics and to exploit the feasibility of such a multiple scattering analysis. We show that by using a neural network approach, we are able to reconstruct the muon energy for Eμ<E_\mu<40 GeV. The test beam data provide an absolute energy calibration, which allows us to apply this method to MACRO data.Comment: 25 pages, 11 figures, Submitted to Nucl. Instr. & Meth.

    The primary cosmic ray composition between 10**15 and 10**16 eV from Extensive Air Showers electromagnetic and TeV muon data

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    The cosmic ray primary composition in the energy range between 10**15 and 10**16 eV, i.e., around the "knee" of the primary spectrum, has been studied through the combined measurements of the EAS-TOP air shower array (2005 m a.s.l., 10**5 m**2 collecting area) and the MACRO underground detector (963 m a.s.l., 3100 m w.e. of minimum rock overburden, 920 m**2 effective area) at the National Gran Sasso Laboratories. The used observables are the air shower size (Ne) measured by EAS-TOP and the muon number (Nmu) recorded by MACRO. The two detectors are separated on average by 1200 m of rock, and located at a respective zenith angle of about 30 degrees. The energy threshold at the surface for muons reaching the MACRO depth is approximately 1.3 TeV. Such muons are produced in the early stages of the shower development and in a kinematic region quite different from the one relevant for the usual Nmu-Ne studies. The measurement leads to a primary composition becoming heavier at the knee of the primary spectrum, the knee itself resulting from the steepening of the spectrum of a primary light component (p, He). The result confirms the ones reported from the observation of the low energy muons at the surface (typically in the GeV energy range), showing that the conclusions do not depend on the production region kinematics. Thus, the hadronic interaction model used (CORSIKA/QGSJET) provides consistent composition results from data related to secondaries produced in a rapidity region exceeding the central one. Such an evolution of the composition in the knee region supports the "standard" galactic acceleration/propagation models that imply rigidity dependent breaks of the different components, and therefore breaks occurring at lower energies in the spectra of the light nuclei.Comment: Submitted to Astroparticle Physic

    The Observation of Up-going Charged Particles Produced by High Energy Muons in Underground Detectors

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    An experimental study of the production of up-going charged particles in inelastic interactions of down-going underground muons is reported, using data obtained from the MACRO detector at the Gran Sasso Laboratory. In a sample of 12.2 10^6 single muons, corresponding to a detector livetime of 1.55 y, 243 events are observed having an up-going particle associated with a down-going muon. These events are analysed to determine the range and emission angle distributions of the up-going particle, corrected for detection and reconstruction efficiency. Measurements of the muon neutrino flux by underground detectors are often based on the observation of through-going and stopping muons produced in νμ\nu_\mu interactions in the rock below the detector. Up-going particles produced by an undetected down-going muon are a potential background source in these measurements. The implications of this background for neutrino studies using MACRO are discussed.Comment: 18 pages, 9 figures. Accepted by Astrop. Physic

    Measurement of the residual energy of muons in the Gran Sasso underground Laboratories

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    The MACRO detector was located in the Hall B of the Gran Sasso underground Laboratories under an average rock overburden of 3700 hg/cm^2. A transition radiation detector composed of three identical modules, covering a total horizontal area of 36 m^2, was installed inside the empty upper part of the detector in order to measure the residual energy of muons. This paper presents the measurement of the residual energy of single and double muons crossing the apparatus. Our data show that double muons are more energetic than single ones. This measurement is performed over a standard rock depth range from 3000 to 6500 hg/cm^2.Comment: 28 pages, 9 figure
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