Production and decay of excited electrons at the LHC

The European Physical Journal C - We study single production of excited electrons at the CERN LHC through contact interactions of fermions. Subsequent decays of excited electrons to ordinary...     

Stroboscopic and acoustic measures of inspiratory phonation

Inspiratory phonation (IP) is the production of voice as air is taken into the lungs. Although IP is promoted as a laryngeal assessment and voice treatment technique, it has been described quantitatively in very few speakers. This study quantified changes in laryngeal adduction, fundamental frequency, and intensity during IP relative to expiratory phonation (EP). We hypothesized that IP would increase laryngeal abduction and fundamental frequency. The experiment was a within-subjects, repeated measures design with each subject serving as her own control. Participants were 10 females (ages 19-50 years) who underwent simultaneous transoral videostrobolaryngoscopy and acoustic voice recording. We found that membranous vocal fold contact decreased significantly during IP relative to EP, while the trends for change of ventricular fold squeeze during IP varied across individuals. Vocal fundamental frequency increased significantly during IP relative to EP, but intensity did not vary consistently across conditions. Without teaching or coaching, changes that occurred during IP did not carry over to EP produced immediately following IP within the same respiratory cycle.     

Focusing,collimation and flux throughput at the IMCA‐CAT bending‐magnet beamline at the Advanced Photon Source

The IMCA‐CAT bending‐magnet beamline was upgraded with a collimating mirror in order to achieve the energy resolution required to conduct high‐quality multi‐ and single‐wavelength anomalous diffraction (MAD/SAD) experiments without sacrificing beamline flux throughput. Following the upgrade, the bending‐magnet beamline achieves a flux of 8 × 10¹¹ photons s^?1 at 1 Å wavelength, at a beamline aperture of 1.5 mrad (horizontal) × 86 µrad (vertical), with energy resolution (limited mostly by the intrinsic resolution of the monochromator optics) δE/E = 1.5 × 10^?4 (at 10 kV). The beamline operates in a dynamic range of 7.5–17.5 keV and delivers to the sample focused beam of size (FWHM) 240 µm (horizontally) × 160 µm (vertically). The performance of the 17‐BM beamline optics and its deviation from ideally shaped optics is evaluated in the context of the requirements imposed by the needs of protein crystallography experiments. An assessment of flux losses is given in relation to the (geometric) properties of major beamline components.     

Tighter Bound of Entropic Uncertainty under the Unruh Effect

The uncertainty principle limits the ability to simultaneously predict measurement outcomes for two non-commuting observables of a quantum particle. However, the uncertainty can be violated by considering a particle as a quantum memory correlated with the primary particle. By modeling an Unruh–Dewitt detector coupled to a massless scalar field, it is explored how the Unruh effect affects the entropic uncertainty and the tighter lower bound for a pair of entangled detectors is probed when one of them is accelerated. It is found that Unruh thermal noise really gives rise to an increase of entropic uncertainty for the given conditions since the correlation between quantum memory and the measured system is decreased. It is shown that the bound of the entropic uncertainty relations, in the presence of memory, can be formulated by introducing the Holevo quantity and mutual information. It is also noticed that Adabi's lower bound is tighter than that of Berta, and just the optimal bound under the Unruh effect. Moreover, it is shown that Berta's lower bound is unrelated to the choice of complementary observables, while the optimal Adabi's lower bound is dependent on the measurement choice. It is worth mentioning that the investigations may offer a better understanding of the entropic uncertainty in a relativistic motion.     

An integrable noncommutative version of the sine-Gordon system

Using the bicomplex approach we discuss an integrable noncommutative system in two-dimensional Euclidean space. It is described by an equation of motion which reduces to the ordinary sine-Gordon equation when the noncommutation parameter is removed, plus a constraint equation which is nontrivial only in the noncommutative case. The implications of this constraint, which is required by integrability but seems to reduce the space of classical solutions, remain to be understood. We show that the system has an infinite number of conserved currents and we give the general recursive relation for constructing them. For the particular cases of lower spin nontrivial currents we work out the explicit expressions and perform a direct check of their conservation. These currents reduce to the usual sine-Gordon currents in the commutative limit. We find classical “localized” solutions to first order in the noncommutativity parameter and describe the Backlund transformations for our system. Finally, we comment on the relation of our noncommutative system to the commutative sine-Gordon system.     

Single‐Electron Pumps and Quantum Current Metrology in the Revised SI

The consequences of the revision of the International System of Units for electrical quantum metrology are discussed herein. Possible applications of single‐electron transport pump devices and other topical state‐of‐the‐art metrology methodologies based on quantum electrical effects are reviewed, with a focus on their potential for and implications on electrical metrology in the future.     

Stroboscopic study of flux dynamics in superconductors during current-induced breakdown

We have studied current-induced breakdown in type-I superconducting films at time resolutions of 100 nsec by combining a laser stroboscope with magneto-optical flux detection. We find that breakdown occurs through the regular, periodic generation of multiquanta flux tubes whose size is determined by properties intrinsic to the sample. Also, a measurement of flux-tube velocity as a function of penetration distance has been performed and compared with a recent theoretical model.     

Stroboscopic analysis of quasi-periodic anomalies in the pluviometric series of Rome

Summary The hystorical series of meteorological data were often studied in order to detect climatological cycles, usually with some kind of harmonic analysis. Several cycles were detected, but the results were not satisfying, because the component waves show often abrupt variations in amplitude and phase. More recently, a different approach, was introduced considering the series of data as a stochastic sequence, in which quasi-periodic positive or negative anomalies are embedded. This paper deals with the hystorical series of yearly rainfall values at Collegio Romano from 1782 to 1981. First the randomness of the series was tested by comparing the Hurst exponents of the series and of an equally long series of random numbers. Then the series was analysed by a stroboscopic method. The ?speeds? of the strobing window that minimize the second moments of the distribution yield an indication of anomalies periods. Being the time step of the original series 1 year, best results are obtained with a width of the strobing window of 3 years. In order to avoid truncation errors, the maximum period is 1/4 of the duration of the series, namely 50 y. Among the periods detected are the cycles of Wagner (15 y), luni-solar Toaldian (18 y), the double solar cycle of Hale (22 y), the cycle of Brukner (30 y) and a cycle of about 44 y detected by Vercelli. All those periods correspond to those calculated by Njau from orbital considerations.     

Geodesics on extensions of Lie groups and stability: the superconductivity equation

The equations of motion of an ideal charged fluid, respectively the superconductivity equation (both in a given magnetic field) are showed to be geodesic equations of a general, respectively a central extension of the group of volume preserving diffeomorphisms with right invariant metrics. For this, quantization of the magnetic flux is required. We do curvature computations in both cases in order to get informations about the stability.     

Stroboscopic XMCD-PEEM imaging of standing and propagating spinwave modes in permalloy thin-film structures

Using synchrotron-based stroboscopic photoemission electron microscopy with X-ray circular dichroism as contrast method, we have investigated the high-frequency response of permalloy thin-film structures. Standing precessional modes have been studied in rectangular elements (16 × 32 μm², 10 nm thick) with a high time resolution of about 15 ps in the low-α mode of BESSY. With increasing amplitude of the applied magnetic AC field the particle is driven from an initial symmetric Landau flux-closure state into an asymmetric state and finally into a single-domain state magnetized perpendicular to the applied field H_AC. The electromagnetic microwave field thus can induces a net magnetization in a small particle. This behaviour is a result of the constant throughput of energy (open system) that allows for an increase of local order, contrary to the usual increase on entropy in closed systems. A propagating spinwave in an ultrathin elliptical particle (semi axes 6 × 12 μm², 3 nm thick) was observed in a snapshot series with 25 ps time increment. The phase front of the spinwave with large precessional angle (bright contrast) propagates with a velocity of 8100 m/s, i.e. much faster than typical domain wall velocities in permalloy.     

Performance studies of a full-length prototype for the CASTOR forward calorimeter at the CMS experiment

The Time-Of-Flight detector (TOF) of the ALICE experiment at the CERN LHC is based on Multi-gap Resistive Plate Chambers (MRPCs). The TOF detector consists of 152928 readout channels covering a total area of 141 m². In this paper the results of the calibration with cosmic-ray data collected during 2009 are presented.     

X‐ray absorption study of the local structure at the NiO/oxide interfaces

This work reports an X‐ray absorption near‐edge structure (XANES) spectroscopy study at the Ni K‐edge in the early stages of growth of NiO on non‐ordered SiO₂, Al₂O₃ and MgO thin films substrates. Two different coverages of NiO on the substrates have been studied. The analysis of the XANES region shows that for high coverages (80 Eq‐ML) the spectra are similar to that of bulk NiO, being identical for all substrates. In contrast, for low coverages (1 Eq‐ML) the spectra differ from that of large coverages indicating that the local order around Ni is limited to the first two coordination shells. In addition, the results also suggest the formation of cross‐linking bonds Ni—O—M (M = Si, Al, Mg) at the interface.