Search results for "PARTICLES"
showing 10 items of 8085 documents
Nucleon mass and pion-nucleon sigma term from a chiral analysis of lattice QCD world data
2014
The chiral behavior of the nucleon mass is studied within the covariant SU(2) baryon chiral perturbation theory up to order p4. Lattice QCD data for the ensembles of 2 and 2 + 1 flavors are separately fitted, paying special attention to explicit Δ(1232) degrees of freedom, finite volume corrections and finite spacing effects. In the case of the 2 flavor ensemble, we fit simultaneously nucleon mass data together with new and updated data for the σπN term both in their dimensionless forms and determine a Sommer-scale of r0 = 0.493(23) fm. We obtain low-energy constants of natural size that are compatible with the rather linear pion-mass dependence observed in lattice QCD and report a prelimin…
APOGEE Data Releases 13 and 14: Data and Analysis
2018
Data and analysis methodology used for the SDSS/APOGEE Data Releases 13 and 14 are described, highlighting differences from the DR12 analysis presented in Holtzman (2015). Some improvement in the handling of telluric absorption and persistence is demonstrated. The derivation and calibration of stellar parameters, chemical abundances, and respective uncertainties are described, along with the ranges over which calibration was performed. Some known issues with the public data related to the calibration of the effective temperatures (DR13), surface gravity (DR13 and DR14), and C and N abundances for dwarfs (DR13 and DR14) are highlighted. We discuss how results from a data-driven technique, Th…
Neutron imaging and tomography: Applications in food science
2018
International audience; Neutron imaging and tomography allow observing the structure of large objects (from few to hundred centimeters) at a resolution around 100 μm. This non-destructive method is based on the detection of the transmission of a neutron beam through an object in 2D (imaging) or 3D after rotating the sample (tomography). The components of the object attenuate the neutron beam differently, depending on their composition, and produce accurate pictures of objects which give information about their structure. Neutron imaging has been used for quality control purposes in industries (aircraft, motor engineering...), but also find application from materials sciences (fuel cells, li…
Antineutrino monitoring of spent nuclear fuel
2016
Military and civilian applications of nuclear energy have left a significant amount of spent nuclear fuel over the past 70 years. Currently, in many countries world wide, the use of nuclear energy is on the rise. Therefore, the management of highly radioactive nuclear waste is a pressing issue. In this letter, we explore antineutrino detectors as a tool for monitoring and safeguarding nuclear waste material. We compute the flux and spectrum of antineutrinos emitted by spent nuclear fuel elements as a function of time, and we illustrate the usefulness of antineutrino detectors in several benchmark scenarios. In particular, we demonstrate how a measurement of the antineutrino flux can help to…
Model building on the non-factorisable type IIA T6/(Z4×ΩR) orientifold
2016
We construct global semi-realistic supersymmetric models with intersecting D6-branes on the non-factorisable orientifold . The non-factorisable structure gives rise to differences compared to the factorisable case: additional conditions for the three-cycles to be Lagrangian and extra constraints on the wrapping numbers for building fractional cycles.
High Gradient Performance of an S-Band Backward Traveling Wave Accelerating Structure for Medical Hadron Therapy Accelerators
2018
The high-gradient performance of an accelerating structure prototype for a medical proton linac is presented. The structure was designed and built using technology developed by the CLIC collaboration and the target application is the TULIP (Turning Linac for Proton therapy) proposal developed by the TERA foundation. The special feature of this design is to produce gradient of more than 50 MV /m in low-β accelerating structures (v/c=0.38). The structure was tested in an S-band test stand at CERN. During the tests, the structure reached over above 60 MV/m at 1.2 μs pulse length and breakdown rate of about 5x10⁻⁶ bpp. The results presented include ultimate performance, long term behaviour and …
Measurement of the laser resonance ionization efficiency for lutetium
2019
Abstract The development of a highly efficient resonance ionization scheme for lutetium is presented. A laser ion source, based on the all-solid-state Titanium:sapphire laser system, was used at the 30 keV RISIKO off-line mass separator to characterize different possible optical excitation schemes in respect to their ionization efficiency. The developed laser resonance ionization scheme can be directly applied to the use at radioactive ion beam facilities, e. g. at the CERN-MEDICIS facility, for large-scale production of medical radioisotopes.
Microbiology and atmospheric processes: biological, physical and chemical characterization of aerosol particles
2008
Abstract. The interest in bioaerosols has traditionally been linked to health hazards for humans, animals and plants. However, several components of bioaerosols exhibit physical properties of great significance for cloud processes, such as ice nucleation and cloud condensation. To gain a better understanding of their influence on climate, it is therefore important to determine the composition, concentration, seasonal fluctuation, regional diversity and evolution of bioaerosols. In this paper, we will review briefly the existing techniques for detection, quantification, physical and chemical analysis of biological particles, attempting to bridge physical, chemical and biological methods for …
Ray optics for absorbing particles with application to ice crystals at near-infrared wavelengths
2018
Abstract Light scattering by particles large compared to the wavelength of incident light is traditionally solved using ray optics which considers absorption inside the particle approximately, along the ray paths. To study the effects rising from this simplification, we have updated the ray-optics code SIRIS to take into account the propagation of light as inhomogeneous plane waves inside an absorbing particle. We investigate the impact of this correction on traditional ray-optics computations in the example case of light scattering by ice crystals through the extended near-infrared (NIR) wavelength regime. In this spectral range, ice changes from nearly transparent to opaque, and therefore…
The influence of the wind direction and plants on the variability of topsoil magnetic susceptibility in industrial and urban areas of southern Poland
2016
Volume magnetic susceptibility (κ) was measured on the soil surface and in the vertical topsoil profile within a 300 km2 area located in an urban-industrial conurbation. The results were compared to plant species compositions in the forest storeys, elevation above sea level, and terrain geomorphology. The content and mineral composition of the magnetic fraction were determined in the soil horizons. It was found that the extent of the area with enhanced topsoil magnetic susceptibility was similar to the dominant wind direction (south–west). Enhanced κ values were observed for the soil at the forest margin on the leeward side of the emitters as well as at sites located on exposed local elevat…