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We report on the results of the LISA Pathfinder (LPF) free-fall mode experiment, in which the control force needed to compensate the quasistatic differential force acting on two test masses is applied intermittently as a series of "impulse" forces lasting a few seconds and separated by roughly 350 s periods of true free fall. This represents an alternative to the normal LPF mode of operation in which this balancing force is applied continuously, with the advantage that the acceleration noise during free fall is measured in the absence of the actuation force, thus eliminating associated noise and force calibration errors. The differential acceleration noise measurement presented here with the free-fall mode agrees with noise measured with the continuous actuation scheme, representing an important and independent confirmation of the LPF result. An additional measurement with larger actuation forces also shows that the technique can be used to eliminate actuation noise when this is a dominant factor. © 2019 authors. Published by the American Physical Society.

The Earth's naturally occurring Schumann resonances (SR) are composed of a quasi-continuous background component and a larger-amplitude, short-duration transient component, otherwise called ‘Q-burst’ (Ogawa et al., 1967). Sprites in the mesosphere are also known to accompany the energetic positive ground flashes that launch the Q-bursts (Boccippio et al., 1995). Spectra of the background Schumann Resonances (SR) require a natural stabilization period of ~10–12 min for the three conspicuous modal parameters to be derived from Lorentzian fitting. Before the spectra are computed and the fitting process is initiated, the raw time series data need to be properly filtered for local cultural noise, narrow band interference as well as for large transients in the form of global Q-bursts. Mushtak and Williams (2009) describe an effective technique called Isolated Lorentzian (I-LOR), in which, the contributions from local cultural and various other noises are minimized to a great extent. An automated technique based on median filtering of time series data has been developed. These special lightning flashes are known to have greater contribution in the ELF range (below 1 kHz) compared to general negative CG strikes (Huang et al., 1999; Cummer et al., 2006). The global distributions of these Q-bursts have been studied by Huang et al. (1999) Rhode Island, USA by wave impedance methods from single station ELF measurements at Rhode Island, USA and from Japan Hobara et al. (2006). The present work aims to demonstrate the effect of Q- bursts on SR background spectra using GPS time-stamped observation of TLEs. It is observed that the Q-bursts selected for the present work do alias the background spectra over a 5-s period, though the amplitudes of these Q- bursts are far below the background threshold of 16 Core Standard Deviation (CSD) so that they do not strongly alias the background spectra of 10–12 min duration. The examination of one exceptional Q-burst shows that appreciable spectral aliasing can occur even when 12-min spectral integrations are considered. The statistical result shows that for a 12-min spectrum, events above 16 CSD are capable of producing significant frequency aliasing of the modal frequencies, although the intensity aliasing might have a negligible effect unless the events are exceptionally large (~200 CSD). The spectral CSD methodology may be used to extract the time of arrival of the Q-burst transients. This methodology may be combined with a hyperbolic ranging, thus becoming an effective tool to detect TLEs globally with a modest number of networked observational stations.

A questionnaire was developed by the members of WG12 of EURADOS in order to establish an overview of the current status of eye lens radiation dose monitoring in hospitals. The questionnaire was sent to medical physicists and radiation protection officers in hospitals across Europe. Specific topics were addressed in the questionnaire such as: knowledge of the proposed eye lens dose limit; monitoring and dosimetry issues; training and radiation protection measures. The results of the survey highlighted that the new eye lens dose limit can be exceeded in interventional radiology procedures and that eye lens protection is crucial. Personnel should be properly trained in how to use protective equipment in order to keep eye lens doses as low as reasonably achievable. Finally, the results also highlighted the need to improve the design of eye dosemeters in order to ensure satisfactory use by workers.

El objetivo de este proyecto es dimensionar y optimizar el diseño del sistema de ultra alto vacío (UHV) de la nueva línea experimental de luz infrarroja, de nombre MIRAS, del sincrotrón ALBA. Para ello se utiliza el software MolFlow+, un software que utiliza el principio de Monte Carlo para simular el vacío del objeto de estudio y así obtener los perfiles de presión a lo largo del mismo. En primer lugar, mediante la reproducción con MolFlow+ del sector del anillo de almacenamiento (storage ring) donde se situará la nueva línea, se simula el sistema de vacío y se comparan los valores obtenidos con los datos experimentales disponibles, a fin de validar el software y su correcta utilización. Para ello, un estudio paramétrico de las variables más críticas se lleva a cabo, logrando calibrar el modelo de simulación. En base a los conocimientos adquiridos con esta simulación preliminar, se pasa a añadir al modelo la nueva línea experimental, para así reproducir el efecto de ésta sobre el vacío del acelerador y poder realizar el estudio de dimensionamiento y optimización. Concretamente se determina la configuración de bombas y componentes adecuada para obtener el perfil de presión requerido y asegurar una transición plana de forma que el vacío del acelerador no se vea afectado. De forma paralela, se redefine el sistema mecánico partiendo de un diseño preliminar facilitado por el sincrotrón SOLEIL, manteniendo la misma funcionalidad pero evitando alguna incidencia con el resto de componentes presentes en el storage ring y abaratando costes. El resultado de este estudio será la base de la implementación final de la línea, aportando la disposición y la capacidad adecuada de los componentes de bombeo acorde con los requisitos demandados y garantizando un óptimo diseño mecánico.

We study theoretically the Čerenkov-type second-harmonic generation by a Gaussian beam in quadratic nonlinear media with periodically reverted ferroelectric domains. In particular, we consider the role of fundamental beam width on the harmonic emission process. We show that varying the beam width of the fundamental wave not only affects the strength of the emitted Čerenkov harmonic signal but also changes the sensitivity of the emission process to wavelength tuning.

The purpose of this study was to develop an optical tomography to measure a gel dosimeter. The gel used was MAGIC and all the elements needed for its measurement were studied the measurement settings analyzed and optimized. The main part of this study was the realization of a data transformation code to reconstruct the dose distribution from experimental data. The results were compared with Monte Carlo simulations. The most important conclusion of the study is that the resulting 2D distributions show inhomogenties exceeding the quality assurance limits of radiation therapy necessitating further research. Outgoing

Paperboard is widely used in different applications, such as packaging and graphic printing, among others. Consumption of recycled paper is growing, which has led the paper-mill packaging industry to apply strict quality controls. This means that it is very important to develop methods to test the quality of recycled products. In this article, we focus on determining the recovered-fiber content of paperboard samples by applying Fourier transform mid-infrared (FT-MIR) spectroscopy in combination with multivariate statistical methods. To this end, two very fast, nondestructive approaches were applied: classification and quantification. The first approach is based on classifying unknown paperboard samples into two groups: high and low recovered-fiber content. Conversely, under the quantification approach, the content of recovered fiber in the incoming paperboard samples is determined. The experimental results presented in this article show that the classification approach, which classifies unknown incoming paperboard samples, is highly accurate and that the quantification approach has a root mean square error of prediction of about 4.1.

El present treball és un estudi sobre la possibilitat de l’anàlisi de vernissos antics aplicats en retaules i pintures mitjançant FTIR de transmissió i ATR. S’entén per vernissos antics tant aquells que van ser aplicats dins l’etapa final del procés de producció de l’obra, com els que van ser aplicats en intervencions posteriors. Els anàlisis s’han dut a terme dins la franja de l’infraroig mitjà: en primer lloc s’han seleccionat els materials de referència a utilitzar en base al seu ús al llarg de la història com a ingredients de vernissos i per la seva disponibilitat a l’hora d’adquirir-los, a continuació s’han analitzat mitjançant FTIR de transmissió i FTIR d’ATR, s’han classificat les substàncies i s’han estudiat els espectres obtinguts a fi de detectar les bandes que permeten distingir cada material. Les mostres reals s’han extret de la taula dreta del retaule de Martí Bernat “Flagel·lació, coronació d’espines i Crist davant Pilat” (1490) i del fragment del retaule de la Casa de la Ciutat de Tortosa (segona meitat del s. XVI), dissenyat per Martín García Mendoza, tallat per Joan Bellver i pintat i daurat per Joan Dessí: degut a la mida de les mostres extretes aquestes s’han analitzat amb microspectroscòpia de FTIR. En base als resultats obtinguts en l’anàlisi dels materials de referència s’han deduït els components principals del vernís.