Atmospheric muon background in the ANTARES detector

An evaluation of the background due to atmospheric muons in the ANTARES high energy neutrino telescope is presented. Two different codes for atmospheric shower simulation have been used. Results from comparisons between these codes at sea level and detector level are presented. The first results on the capability of ANTARES to reject this class of background are given.Comment: 4 pages, 4 figures, To appear in Proceedings of the 29th International Cosmic Ray Conference (ICRC 2005), Pune, India, 3 - 10 Aug 200

Nuclear Track Detectors for Environmental Studies and Radiation Monitoring

Several improvements were made for Nuclear Track Detectors (NTDs) used for environmental studies and for particle searches. A new method was used to determine the bulk etch rate of CR39 and Makrofol NTDs. It is based on the simultaneous measurement of the diameter and of the height of etch-pit cones caused by relativistic heavy ions (158 A GeV Pb(82+) and In(49+) ions) and their fragments. The use of alcohol in the etching solution improves the surface quality of NTDs and it raises their thresholds. The detectors were used for the determination of nuclear fragmentation cross sections of Iron and Silicon ions of 1.0 and 0.41 GeV/nucleon. These measurements are important for the determination of doses in hadron therapy and for doses received by astronauts. The detectors were also used in the search of massive particles in the cosmic radiation, for the determination of the mass spectrum of cosmic rays and for the evaluation of Po(210) alpha decay and of natural radon concentrations.Comment: 7 pages, 5 EPS figures. Presented at the 10th Topical Seminar on Innovative Particle and Radiation Detectors, 1-5 October 2006, Siena, Ital

Triboelectric characterization of colloidal TiO2 for energy harvesting applications

Nowadays, energy-related issues are of paramount importance. Every energy transformation process results in the production of waste heat that can be harvested and reused, representing an ecological and economic opportunity. Waste heat to power (WHP) is the process of converting the waste heat into electricity. A novel approach is proposed based on the employment of liquid nano colloids. In this work, the triboelectric characterization of TiO2 nanoparticles dispersed in pure water and flowing in a fluorinated ethylene propylene (FEP) pipe was conducted. The idea is to exploit the waste heat to generate the motion of colloidal TiO2 through a FEP pipe. By placing an Al ring electrode in contact with the pipe, it was possible to accumulate electrostatic charges due to the triboelectric effect between the fluid and the inner pipe walls. A peristaltic pump was used to drive and control the flow in order to evaluate the performances in a broad fluid dynamic spectrum. The system generated as output relatively high voltages and low currents, resulting in extracted power ranging between 0.4 and 0.6 nW. By comparing the power of pressure loss due to friction with the extracted power, the electro-kinetic efficiency was estimated to be 20%

On the Pyroelectric and Triboelectric Phenomena in Ferrofluids

Owing to the waste of energy originated by any physical or chemical process, approaches for reducing the energy losses have been conceived and, nowadays, energy recovery and conversion systems represent a worldwide-recognized solution. The advent of colloidal-based cybernetic systems highlights the essential role of energy harvesting, storage, and management capabilities coped by colloidal energetic systems. In this work, an alternative to thermoelectricity generation is demonstrated by means of a magnetic colloid based on Fe3O4 nanoparticles (NPs). The ferrofluid (FF) tribo- and pyroelectric features are explored in order to increase the amount of harvested energy. The findings suggest that the FF shows both triboelectric and pyroelectric charge displacement. A capacitive electrode is more efficient for accumulating potentials up to 48 V developed by triboelectricity while a resistive one is essential to collect pyroelectric charges up to 22 nA, which helped to estimate the FF pyroelectric coefficient, reaching the remarkable value of 25.2 μCm−2 K−1. A simplified equivalent model of the inductive setup is proposed, suggesting that increasing the fluid temperature a reduction of FF inductance due to demagnetization effects occurs

Liquid-state pyroelectric energy harvesting

Increasing the sustainability of energy generation can be pursued by harvesting extremely low enthalpy sources: low temperature differences between cold and hot reservoirs are easily achieved in every industrial process, both at large and small scales, in plants as well as in small appliances, vehicles, natural environments, and human bodies. This paper presents the assessment and efficiency estimate of a liquid-state pyroelectric energy harvester, based on a colloid containing barium titanate nanoparticles and ferrofluid as a stabilizer. The liquid is set in motion by an external pump to control velocity, in a range similar to the one achieved by Rayleigh–Bénard convection, and the colloid reservoir is heated. The colloid is injected into a Fluorinated Ethylene Propylene pipe where titanium electrodes are placed to collect electrical charges generated by pyroelectricity on the surface of the nanoparticles, reaching 22.4% of the ideal Carnot efficiency of a thermal machine working on the same temperature drop. The maximum extracted electrical power per unit of volume is above 7 mW/m3 with a ΔT between electrodes of 3.9 K

The accuracy of the motor imagery and the ball reception in children

Estudios recientes observaron que las imágenes motrices se desarrollan de forma entrelazada con el desarrollo de las habilidades motrices en niños. La finalidad de este estudio es analizar en qué medida la imagen motriz de los elementos necesarios para resolver un problema motor (la recepción de un balón), se relaciona con los niveles de habilidad en niños (3 - 9 años). La muestra estuvo formada por 215 participantes (87 chicos y 118 chicas), (M = 5,94, DT = 1,47). Se ha utilizado una metodología mixta: dibujos, indicaciones gestuales, verbalización del pensamiento y una prueba práctica de recepción de balón. El MANOVA reveló diferencias significativas en las capacidades meta-cognitivas y motrices en función de las etapas de desarrollo. Un análisis de ecuaciones estructurales reveló que las capacidades meta-cognitivas median la relación entre las etapas de desarrollo y la habilidad de recepción de móviles. Se discuten sus repercusiones en el aprendizaje motorRecent studies have found that motor imaginery is developed linked to the development of motor skills in children. The purpose of this study is to analyze how the motor imaginery of the principal elements to solve a motor problem (ball reception) relates to the motor skill levels in children (3-9 years). The sample consisted of 215 participants (87 boys and 118 girls), (M = 5.94, SD = 1.47).We used a mixed methodology: drawings, gestural prompts, verbalization of thought and a practical test of ball reception. The MANOVA revealed significant differences in the meta-cognitive abilities and motor function of the developmental stages. A structural equation analysis revealed that meta-cognitive abilities mediate the relationship between the stages of development and the ability in the reception of moving objects. Their implications in motor learning are discusse

Bulk Etch Rate Measurements and Calibrations of Plastic Nuclear Track Detectors

New calibrations of CR39 and Makrofol nuclear track detectors have been obtained using 158 A GeV Pb (82+) and In (49+) ions; a new method for the bulk etch rate determination, using both cone height and base diameter measurements was developed. The CR39 charge resolution based on the etch-pit base area measurement is adequate to identify nuclear fragments in the interval 7 <= Z/beta <= 49. For CR39 the detection threshold is at REL~50 MeV cm^2/g, corresponding to a nuclear fragment with Z/beta~7. Base cone area distributions for Makrofol foils exposed to Pb (82+) ions have shown for the first time all peaks due to nuclear fragments with Z > 50; the distribution of the etched cone heights shows well separated individual peaks for Z/beta = 78 - 83 (charge pickup). The Makrofol detection threshold is at REL 2700 MeV cm^2/g, corresponding to a nuclear fragment with Z/beta~50.Comment: 11 pages, 5 EPS figures. Submitted to Nucl. Instr. Meth.

Acoustic charge transport in n-i-n three terminal device

We present an unconventional approach to realize acoustic charge transport devices that takes advantage from an original input region geometry in place of standard Ohmic input contacts. Our scheme is based on a n-i-n lateral junction as electron injector, an etched intrinsic channel, a standard Ohmic output contact and a pair of in-plane gates. We show that surface acoustic waves are able to pick up electrons from a current flowing through the n-i-n junction and steer them toward the output contact. Acoustic charge transport was studied as a function of the injector current and bias, the SAW power and at various temperatures. The possibility to modulate the acoustoelectric current by means of lateral in-plane gates is also discussed. The main advantage of our approach relies on the possibility to drive the n-i-n injector by means of both voltage or current sources, thus allowing to sample and process voltage and current signals as well.Comment: 9 pages, 3 figures. Submitted to Applied Physics Letter

High frequency mechanical excitation of a silicon nanostring with piezoelectric aluminum nitride layers

A strong trend for quantum based technologies and applications follows the avenue of combining different platforms to exploit their complementary technological and functional advantages. Micro and nano-mechanical devices are particularly suitable for hybrid integration due to the easiness of fabrication at multi-scales and their pervasive coupling with electrons and photons. Here, we report on a nanomechanical technological platform where a silicon chip is combined with an aluminum nitride layer. Exploiting the AlN piezoelectricity, Surface Acoustic Waves are injected in the Si layer where the material has been localy patterned and etched to form a suspended nanostring. Characterizing the nanostring vertical displacement induced by the SAW, we found an external excitation peak efficiency in excess of 500 pm/V at 1 GHz mechanical frequency. Exploiting the long term expertise in silicon photonic and electronic devices as well as the SAW robustness and versatility, our technological platform represents a strong candidate for hybrid quantum systems