66 research outputs found
Taxonomy of the extrasolar planet
When a star is described as a spectral class G2V, we know that the star is
similar to our Sun. We know its approximate mass, temperature, age, and size.
When working with an extra-solar planet database, it is very useful to have a
taxonomy scale (classification) such as, for example, the Harvard
classification for stars. The taxonomy has to be easily interpreted and present
the most relevant information about extra-solar planets. I propose the
following the extra-solar planet taxonomy scale with four parameters. The first
parameter concerns the mass of an extra-solar planet in the form of the units
of the mass of other known planets, where M represents the mass of Mercury, E
that of Earth, N Neptune, and J Jupiter. The second parameter is the planet's
distance from its parent star (semi-major axis) described in logarithm with
base 10. The third parameter is the mean Dyson temperature of the extra-solar
planet, for which I established four main temperature classes; F represents the
Freezing class, W the Water Class, G the Gaseous Class, and R the Roasters
Class. I devised one additional class, however: P, the Pulsar Class, which
concerns extra-solar planets orbiting pulsar stars. The fourth parameter is
eccentricity. If the attributes of the surface of the extra-solar planet are
known, we are able to establish this additional parameter where t represents a
terrestrial planet, g a gaseous planet, and i an ice planet. According to this
taxonomy scale, for example, Earth is 1E0W0t, Neptune is 1N1.5F0i, and
extra-solar planet 55 Cnc e is 9E-1.8R1. Key words: Catalogues - Extra-solar
planet - Habitable zone - PlanetsComment: 11 pages, 1 figure, 4 table
The trigger system of the NOMAD experiment
The NOMAD trigger system is described in the present paper. It is made up of a largearea plastic scintillator veto system, two trigger scintillator planes inside a 0.4~Tmagnetic field and their associated trigger electronics. Special features of the systemconsist of the use of proximity mesh photomultipliers which allow the trigger scintillators to operate in the magnetic field, and the use of custom-built VME moduleswhich perform the trigger logic decisions, the signal synchronisation and gate generation,event counting and livetime calculations. This paper also includes a description of each of the NOMAD triggers, with their calculated and measured rates, efficiencies and livetimes
Scan Free GEXRF in the Soft X ray Range for the Investigation of Structured Nanosamples
Scan free grazing emission X ray fluorescence spectroscopy GEXRF is an established technique for the investigation of the elemental depth profiles of various samples. Recently it has been applied to investigating structured nanosamples in the tender X ray range. However, lighter elements such as oxygen, nitrogen or carbon cannot be efficiently investigated in this energy range, because of the ineffective excitation. Moreover, common CCD detectors are not able to discriminate between fluorescence lines below 1 keV. Oxygen and nitrogen are important components of insulation and passivation layers, for example, in silicon oxide or silicon nitride. In this work, scan free GEXRF is applied in proof of concept measurements for the investigation of lateral ordered 2D nanostructures in the soft X ray range. The sample investigated is a Si3N4 lamellar grating, which represents 2D periodic nanostructures as used in the semiconductor industry. The emerging two dimensional fluorescence patterns are recorded with a CMOS detector. To this end, energy dispersive spectra are obtained via single photon event evaluation. In this way, spatial and therefore angular information is obtained, while discrimination between different photon energies is enabled. The results are compared to calculations of the sample model performed by a Maxwell solver based on the finite elements method. A first measurement is carried out at the UE56 2 PGM 2 beamline at the BESSY II synchrotron radiation facility to demonstrate the feasibility of the method in the soft X ray range. Furthermore, a laser produced plasma source LPP is utilized to investigate the feasibility of this technique in the laboratory. The results from the BESSY II measurements are in good agreement with the simulations and prove the applicability of scan free GEXRF in the soft X ray range for quality control and process engineering of 2D nanostructures. The LPP results illustrate the chances and challenges concerning a transfer of the methodology to the laborator
Potential Output and Fiscal Rules in a Monetary Union Under Asymmetric Information 2nd Ed
Shape and element sensitive reconstruction of periodic nanostructures with grazing incidence x ray fluorescence analysis and machine learning
The characterization of nanostructured surfaces with sensitivity in the sub nm range is of high importance for the development of current and next generation integrated electronic circuits. Modern transistor architectures for, e.g., FinFETs are realized by lithographic fabrication of complex, well ordered nanostructures. Recently, a novel characterization technique based on X ray fluorescence measurements in grazing incidence geometry was proposed for such applications. This technique uses the X ray standing wave field, arising from an interference between incident and the reflected radiation, as a nanoscale sensor for the dimensional and compositional parameters of the nanostructure. The element sensitivity of the X ray fluorescence technique allows for a reconstruction of the spatial element distribution using a finite element method. Due to a high computational time, intelligent optimization methods employing machine learning algorithms are essential for timely provision of results. Here, a sampling of the probability distributions by Bayesian optimization is not only fast, but it also provides an initial estimate of the parameter uncertainties and sensitivities. The high sensitivity of the method requires a precise knowledge of the material parameters in the modeling of the dimensional shape provided that some physical properties of the material are known or determined beforehand. The unknown optical constants were extracted from an unstructured but otherwise identical layer system by means of soft X ray reflectometry. The spatial distribution profiles of the different elements contained in the grating structure were compared to scanning electron and atomic force microscopy and the influence of carbon surface contamination on the modeling results were discussed. This novel approach enables the element sensitive and destruction free characterization of nanostructures made of silicon nitride and silicon oxide with sub nm resolutio
Grazing incidence X ray fluorescence based characterization of nanostructures for element sensitive profile reconstruction
The anisotropy in the optical constants of quartz crystals for soft Xârays
The refractive index of a yâcut SiO2 crystal surface is reconstructed from orientationâdependent soft Xâray reflectometry measurements in the energy range from 45 to 620â
eV. Owing to the anisotropy of the crystal structure in the (100) and (001) directions, a significant deviation of the measured reflectance at the Si L2,3 and O K absorption edges is observed. The anisotropy in the optical constants reconstructed from these data is also confirmed by ab initio BetheâSalpeter equation calculations for the O K edge. This new experimental data set expands the existing literature data for quartz crystal optical constants significantly, particularly in the nearâedge regions.The refractive index of a yâcut SiO2 crystal surface is reconstructed from polarizationâdependent soft Xâray reflectometry measurements in the energy range from 45 to 620â
eV. The reconstructed anisotropy in the optical constants is also confirmed by ab initio BetheâSalpeter equation calculations of the O K edge.
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