3,079 research outputs found
HESS J1641-463, a very hard spectrum TeV gamma-ray source in the Galactic plane
HESS J1641-463 is a unique source discovered by the High Energy Stereoscopic
System (H.E.S.S.) telescope array in the multi-TeV domain. The source had been
previously hidden in the extended tail of emission from the bright nearby
source HESS J1640-465. However, the analysis of the very-high-energy (VHE) data
from the region at energies above 4 TeV revealed this new source at a
significance level of 8.5. HESS J1641-463 showed a moderate flux level
F(E > 1 TeV) = (3.64 +/- 0.44_stat +/- 0.73_sys) 10^-13 cm^-2s^-1,
corresponding to 1.8% of the Crab Nebula flux above the same energy, and a hard
spectrum with a photon index Gamma = 2.07 +/- 0.1_stat +/- 0.20_sys. The light
curve was investigated for evidence of variability, but none was found on both
short (28-min observation) and long (yearly) timescales. HESS J1641-463 is
positionally coincident with the radio supernova remnant (SNR) G338.5+0.1.
There is no clear X-ray counterpart of the SNR, although Chandra and XMM-Newton
data reveal some weak emission that may be associated. If the emission from
HESS J1641-463 is produced by cosmic ray protons colliding with the ambient
gas, then the proton spectrum extends up to 0.1 PeV (99% confidence level) and
likely to higher energies, > 0.27 PeV (90% confidence level). If this is the
case, then HESS J1641-463 may be a member of a larger source population
contributing to the Galactic cosmic-ray flux around the knee.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherland
The impact of EU enlargement on migration flows
This document is a report commissioned by the Home Office in order to assess the magnitude of potential migration flows to the UK after the enlargement of the European Union (EU). The countries which are expected to join the EU on 1 May 2004 are Cyprus, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia and Slovenia. The aim of the report is to provide extensive information that will be helpful in evaluating the migration potential from
these countries to the UK. This is done by (i) describing the socio-economic situation of the accession countries nowadays and since the early 1990s and comparing it to that of the UK and Germany, (ii) critically reviewing the existing literature that attempts to predict the effects of the current EU enlargement on migration flows, (iii) analysing the so-called Southern enlargement (the accessions of Greece, Portugal and Spain) and comparing it to the current one, and (iv) presenting a quantitative analysis of the effect of the current enlargement on migration to the UK
Assessing the potentiality of Romanian surface waters to produce hydroxyl and nitrite radicals
Quantum Simulation of Quantum Field Theories in Trapped Ions
We propose the quantum simulation of a fermion and an antifermion field modes
interacting via a bosonic field mode, and present a possible implementation
with two trapped ions. This quantum platform allows for the scalable add-up of
bosonic and fermionic modes, and represents an avenue towards quantum
simulations of quantum field theories in perturbative and nonperturbative
regimes.Comment: To be published in Physical Review Letter
Literacidad en refugiados y solicitantes de protección internacional: Factores determinantes de la escritura en español como segunda lengua
El presente estudio se enfoca en la literacidad de refugiados y solicitantes de protección internacional procedentes de China, Ucrania, Eritrea y Siria. En concreto, persigue analizar los factores determinantes de la producción escrita en español de este colectivo. Para ello, se utilizaron dos tareas escritas que se evaluaron en términos de calidad global del texto y de la cantidad y tipo de errores cometidos. Los datos fueron analizados mediante estadÃstica descriptiva, coeficientes de correlación y pruebas de comparación de medias. En lÃneas generales, los resultados revelaron una influencia del género, la asistencia a clase, el nivel educativo y la edad de los participantes en su competencia escrita
Characterisation of AMS H35 HV-CMOS monolithic active pixel sensor prototypes for HEP applications
Monolithic active pixel sensors produced in High Voltage CMOS (HV-CMOS)
technology are being considered for High Energy Physics applications due to the
ease of production and the reduced costs. Such technology is especially
appealing when large areas to be covered and material budget are concerned.
This is the case of the outermost pixel layers of the future ATLAS tracking
detector for the HL-LHC. For experiments at hadron colliders, radiation
hardness is a key requirement which is not fulfilled by standard CMOS sensor
designs that collect charge by diffusion. This issue has been addressed by
depleted active pixel sensors in which electronics are embedded into a large
deep implantation ensuring uniform charge collection by drift. Very first small
prototypes of hybrid depleted active pixel sensors have already shown a
radiation hardness compatible with the ATLAS requirements. Nevertheless, to
compete with the present hybrid solutions a further reduction in costs
achievable by a fully monolithic design is desirable. The H35DEMO is a large
electrode full reticle demonstrator chip produced in AMS 350 nm HV-CMOS
technology by the collaboration of Karlsruher Institut f\"ur Technologie (KIT),
Institut de F\'isica d'Altes Energies (IFAE), University of Liverpool and
University of Geneva. It includes two large monolithic pixel matrices which can
be operated standalone. One of these two matrices has been characterised at
beam test before and after irradiation with protons and neutrons. Results
demonstrated the feasibility of producing radiation hard large area fully
monolithic pixel sensors in HV-CMOS technology. H35DEMO chips with a substrate
resistivity of 200 cm irradiated with neutrons showed a radiation
hardness up to a fluence of ncm with a hit efficiency of
about 99% and a noise occupancy lower than hits in a LHC bunch
crossing of 25ns at 150V
La Trigonometria en els inicis de la matemà tica xinesa : algunes idees per treballar a l'aula
The Nine Chapters is the most important old Chinese mathematical text. It
contains a chapter devoted to solving problems of triangles (chapter 9). The analysis
of the method for solving problems—using the «base and height procedure» or «Gougu
» procedure— together with the comprehension of later contributions of commentators
led us to use old Chinese conceptions for training the XXI century students
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