74 research outputs found
Polarization elements for controlling of a beam of the compact discharge X-ray laser
No full textThe high average power of the compact discharge X-ray laser makes feasible various applications in optical instrumentation and material science. Among them there are polarization measurements that are especially important for optical element characterization and investigation of material properties. An accuracy of polarization measurements strongly depends on a quality of polarizes and phase shifters that are used to change the polarization state of a beam. In this work several types of polarizing elements for the wavelength 46.9 nm are considered. The main attention is paid to those (based on Si/3d-transition metal) multilayer structures that were shown to provide high performance mirrors in this spectral range
The prospects of reflectometry and ellipsometry with Colorado State University tabletop XUV laser
No full textThe capillary discharge ArIX laser (wavelength 46.9nm) is a new device attractive for various applications due to its unique for XUV lasers properties: high average power and compactness. Reflectometry and ellipsometry are among them. The first is capable to provide fundamental data on optical constants of solids, which are still rather limited. Reflection coefficient in this spectral range is highly sensitive to the presence of an over layer at the surface of a sample. This hinders bulk optical constants determination, but offers the possibility to study chemical contamination by ambience. The theory of reflection from a surface with a thin overlayer is developed. It enables to rigorously include overlayer into reflectometry data processing and derive separately the parameters of bulk and overlayer. Ellipsometry in general is more powerful than reflectometry method to measure optical constants. In addition it offers the accurate methods to measure film thickness and properties of magnetic materials. Unfortunately high quality analyzers and polarizers are not available in this spectral range, which requires specific approach to ellipsometric measurements. We discuss and use for this purpose Sc/Si multilayer structures
The prospects of reflectometry and ellipsometry with Colorado State University tabletop XUV laser
No full textThe capillary discharge ArIX laser (wavelength 46.9nm) is a new device attractive for various applications due to its unique for XUV lasers properties : high average power and compactness. Reflectometry and ellipsometry are among them. The first is capable to provide fundamental data on optical constants of solids, which are still rather limited. Reflection coefficient in this spectral range is highly sensitive to the presence of an overlayer at the surface of a sample. This hinders bulk optical constants determination, but offers the possibility to study chemical contamination by ambience. The theory of reflection from a surface with a thin overlayer is developed. It enables to rigorously include overlayer into reflectometry data processing and derive separately the parameters of bulk and overlayer. Ellipsometry in general is more powerful than reflectometry method to measure optical constants. In addition it offers the accurate methods to measure film thickness and properties of magnetic materials. Unfortunately high quality analyzers and polarizers are not available in this spectral range, which requires specific approach to ellipsometric measurements. We discuss and use for this purpose Sc/Si multilayer structures
Study of doubly strange systems using stored antiprotons
No full textBound nuclear systems with two units of strangeness are still poorly known despite their importance for many strong interaction phenomena. Stored antiprotons beams in the GeV range represent an unparalleled factory for various hyperon–antihyperon pairs. Their outstanding large production probability in antiproton collisions will open the floodgates for a series of new studies of systems which contain two or even more units of strangeness at the View the MathML sourceP‾ANDA experiment at FAIR. For the first time, high resolution γ -spectroscopy of doubly strange ΛΛ-hypernuclei will be performed, thus complementing measurements of ground state decays of ΛΛ-hypernuclei at J-PARC or possible decays of particle unstable hypernuclei in heavy ion reactions. High resolution spectroscopy of multistrange Ξ−Ξ−-atoms will be feasible and even the production of Ω−Ω−-atoms will be within reach. The latter might open the door to the |S|=3|S|=3 world in strangeness nuclear physics, by the study of the hadronic Ω−Ω−-nucleus interaction. For the first time it will be possible to study the behavior of View the MathML sourceΞ‾+ in nuclear systems under well controlled conditions
Proposal of a compact repetitive dichromatic x-ray generator with millisecond duty cycle for medical applications
No full textFeasibility studies for the measurement of time-like proton electromagnetic form factors from p ̄ p→ μ+μ- at P ̄ ANDA at FAIR
No full textThis paper reports on Monte Carlo simulation results for future measurements of the moduli of time-like proton electromagnetic form factors, | GE| and | GM| , using the p ̄ p→ μ+μ- reaction at P ̄ ANDA (FAIR). The electromagnetic form factors are fundamental quantities parameterizing the electric and magnetic structure of hadrons. This work estimates the statistical and total accuracy with which the form factors can be measured at P ̄ ANDA , using an analysis of simulated data within the PandaRoot software framework. The most crucial background channel is p ̄ p→ π+π-, due to the very similar behavior of muons and pions in the detector. The suppression factors are evaluated for this and all other relevant background channels at different values of antiproton beam momentum. The signal/background separation is based on a multivariate analysis, using the Boosted Decision Trees method. An expected background subtraction is included in this study, based on realistic angular distributions of the background contribution. Systematic uncertainties are considered and the relative total uncertainties of the form factor measurements are presented
Study of excited Ξ baryons with the P ̄ ANDA detector
No full textThe study of baryon excitation spectra provides insight into the inner structure of baryons. So far, most of the world-wide efforts have been directed towards N∗ and Δ spectroscopy. Nevertheless, the study of the double and triple strange baryon spectrum provides independent information to the N∗ and Δ spectra. The future antiproton experiment P ̄ANDA will provide direct access to final states containing a Ξ ̄ Ξ pair, for which production cross sections up to μb are expected in p ̄p reactions. With a luminosity of L= 10 31 cm- 2 s- 1 in the first phase of the experiment, the expected cross sections correspond to a production rate of ∼106events/day. With a nearly 4 π detector acceptance, P ̄ANDA will thus be a hyperon factory. In this study, reactions of the type p ̄p → Ξ ̄ +Ξ∗ - as well as p ̄p → Ξ ̄ ∗ +Ξ- with various decay modes are investigated. For the exclusive reconstruction of the signal events a full decay tree fit is used, resulting in reconstruction efficiencies between 3 and 5%. This allows high statistics data to be collected within a few weeks of data taking
Proposal of a compact repetitive dichromatic x-ray generator with millisecond duty cycle for medical applications
No full textPrecision resonance energy scans with the PANDA experiment at FAIR
No full textThis paper summarises a comprehensive Monte Carlo simulation study for precision resonance energy scan measurements. Apart from the proof of principle for natural width and line shape measurements of very narrow resonances with PANDA, the achievable sensitivities are quantified for the concrete example of the charmonium-like X(3872) state discussed to be exotic, and for a larger parameter space of various assumed signal cross-sections, input widths and luminosity combinations. PANDA is the only experiment that will be able to perform precision resonance energy scans of such narrow states with quantum numbers of spin and parities that differ from {} J^{{}PC{}} = 1^{{}--{}}{}JPC=1--
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