Extension of charge-state-distribution calculations for ion-solid collisions towards low velocities and many-electron ions

Knowledge of the detailed evolution of the whole charge-state distribution of projectile ions colliding with targets is required in several fields of research such as material science and atomic and nuclear physics but also in accelerator physics, and in particular in regard to the several foreseen large-scale facilities. However, there is a lack of data for collisions in the nonperturbative energy domain and that involve many-electron projectiles. Starting from the etacha model we developed [Rozet, Nucl. Instrum. Methods Phys. Res., Sect. B 107, 67 (1996)10.1016/0168-583X(95)00800-4], we present an extension of its validity domain towards lower velocities and larger distortions. Moreover, the system of rate equations is able to take into account ions with up to 60 orbital states of electrons. The computed data from the different new versions of the etacha code are compared to some test collision systems. The improvements made are clearly illustrated by 28.9MeVu-1Pb56+ ions, and laser-generated carbon ion beams of 0.045 to 0.5MeVu-1, passing through carbon or aluminum targets, respectively. Hence, those new developments can efficiently sustain the experimental programs that are currently in progress on the "next-generation" accelerators or laser facilities.Fil: Lamour, E.. Centre National de la Recherche Scientifique; Francia. Universite de Paris; FranciaFil: Fainstein, Pablo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Galassi, Mariel Elisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Prigent, C.. Centre National de la Recherche Scientifique; Francia. Universite de Paris; FranciaFil: Ramirez, C. A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Rivarola, Roberto Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Rozet, J. P.. Centre National de la Recherche Scientifique; Francia. Universite de Paris; FranciaFil: Trassinelli, M.. Centre National de la Recherche Scientifique; Francia. Universite de Paris; FranciaFil: Vernhet, D.. Centre National de la Recherche Scientifique; Francia. Universite de Paris; Franci

Modulating the phase transition temperature of giant magnetocaloric thin films by ion irradiation

Magnetic refrigeration based on the magnetocaloric effect at room temperature is one of the most attractive alternative to the current gas compression/expansion method routinely employed. Nevertheless, in giant magnetocaloric materials, optimal refrigeration is restricted to the narrow temperature window of the phase transition (Tc). In this work, we present the possibility of varying this transition temperature into a same giant magnetocaloric material by ion irradiation. We demonstrate that the transition temperature of iron rhodium thin films can be tuned by the bombardment of ions of Ne 5+ with varying fluences up to 10 14 ions cm --2 , leading to optimal refrigeration over a large 270--380 K temperature window. The Tc modification is found to be due to the ion-induced disorder and to the density of new point-like defects. The variation of the phase transition temperature with the number of incident ions opens new perspectives in the conception of devices using giant magnetocaloric materials

How can video feedback be used in physical education to support novice learning in gymnastics? Effects on motor learning, self-assessment and motivation

Background: Much of the existing research concerning the use of video feedback (VFB) to enhance motor learning has been undertaken under strictly controlled experimental conditions. Few studies have sought to explore the impact of VFB on the skill learning experience of the students in a structured, school-based physical education (PE) setting. Most of those studies have only used qualitative approaches to implicate the potential value of VFB to enhance skill acquisition, students ’ engagement or self- assessment ability. Using a quantitative approach, the aim of this study was to investigate effects of using VFB on motor skill acquisition, self- assessment ability and motivation in a school-based learning environment (structured PE programme) with novice children learning a gymnastic skill. Method: Two French classes of beginners took part in a typical five-week learning programme in gymnastics. During each of the five, weekly lessons participants carried out the same warm-up routine and exercises. The experimental group (10 girls – 8 boys, 12.4 ± 0.5 years) received VFB intermittently when learning a front handstand to flat back landing. VFB was given after every five attempts, combined with self-assessment and verbal instructions from the teacher. The control group (12 girls – 13 boys, 12.6 ± 0.4 years) received exactly the same training but was not given VFB. In order to assess progress in motor skills, the arm-trunk angle (hand- shoulder-hip) was measured in the sagittal plane just as the hips formed a vertical line with the shoulders. Motivation was assessed using the Situational Motivation Scale questionnaire (Guay, F., R. J. Vallerand, and C. Blanchard. 2000. “ On the Assessment of Situational Intrinsic and Extrinsic Motivation: The Situational Motivation Scale (SIMS). ” Motivation and Emotion 24 (3): 175 – 213), and self-assessment ability was measured by self-perception task scores. Results: Statistical analysis of arm-trunk angle values showed significant differences only for the VFB group between the fifth lesson and all other lessons. Between lessons 4 and 5, the arm-trunk angle value increased significantly from 146.6 ± 16.9 degrees to 161.2 ± 14.2 degrees ( p < .001; ES = 0.94). Self-assessment scores improved significantly for the VFB group between lesson 1 and lesson 2 ( p < 0.01, ES = 1.79) and between lesson 4 to lesson 5 ( p < .01, ES = 0.94). Amotivation decreased significantly for the VFB group between lesson 1 and lesson 5 (3.06 ± 1.42 vs. 2.12 ± 0.62, p < .001, ES = − 0.89). Discussion/conclusion: Our quantitative data, identifying key movement changes as a function of experience in a structured PE programme, were congruent with outcomes of previous qualitative research supporting the role of VFB. This study highlights the potential relevance of using VFB in fostering motor learning, motivation and self-assessment during a PE programme with young children. Future pedagogical research is needed to examine the ways students could use VFB technology for greater self- regulation, with the potential to deliver appropriate movement feedback, based on different levels of experience in students

Electronic temperatures, densities and plasma X-ray emission of a 14.5 GHz Electron-Cyclotron Resonance Ion Source

We have performed a systematic study of the Bremsstrahlung emission from the electrons in the plasma of a commercial 14.5 GHz Electron-Cyclotron Resonance Ion Source. The electronic spectral temperature and the product of ionic and electronic densities of the plasma are measured by analyzing the Bremsstrahlung spectra recorded for several rare gases (Ar, Kr, Xe) as a function of the injected power. Within our uncertainty, we find an average temperature of ? 48 keV above 100W, with a weak dependency on the injected power and gas composition. Charge state distributions of extracted ion beams have been determined as well, providing a way to disentangle the ionic density from the electronic density. Moreover X-ray emission from highly charged argon ions in the plasma has been observed with a high-resolution mosaic crystal spectrometer, demonstrating the feasibility for high-precision measurements of transition energies of highly charged ions, in particular of the magnetic dipole (M1) transition of He-like of argon ions

MAPAS DE PARÂMETROS TEXTURAIS DE SEDIMENTOS DE FUNDO DO COMPLEXO ESTUARINO DE PARANAGUÁ PR

This study aims to describe the bottom sediments distribution on the Paranaguá Bay Complex, a synthesizing of the available data. Between 1988 and 2001 1.187 samples were obtained, which were used in this analysis. The CEP is compose by two main axis denominated Laranjeiras bay (N-S) and Paranaguá bay (EW). The main results shown differences between bottom sediments characteristics of both bays, where the mean grain size on Laranjeiras bay is bigger than on Paranaguá bay, and selection coefficient is near to the same in both bays, except on Guaraqueçaba bay. The quantities of carbonate vary between 5 and 20%, and organic matter varies between 0 and 35% on the CEP.Este estudo tem por objetivo verificar a distribuição das características dos sedimentos de fundo do Complexo Estuarino de Paranaguá, fazendo uma síntese integrada dos dados. As análises foram embasadas em 1.187 amostras coletadas entre os anos de 1988 e 2001. Este Complexo Estuarino é composto por dois eixos principais, denominados baía das Laranjeiras (N-S) e de Paranaguá (L-O). Os resultados obtidos destacam diferenças entre as características dos sedimentos das referidas baías. O diâmetro médio granulométrico da baía das Laranjeiras é maior que na baía de Paranaguá, com grau de seleção semelhante em ambas, exceto a baía de Guaraqueçaba. A distribuição das porcentagens de carbonato biodetrítico (CaCO3) varia entre 5 e 20%, enquanto que a quantidade de matéria orgânica varia entre 0 e 35% no CEP

Measurement of the electric dipole moments for transitions to rubidium Rydberg states via Autler-Townes splitting

We present the direct measurements of electric-dipole moments for $5P_{3/2}\to nD_{5/2}$ transitions with $20<n<48$ for Rubidium atoms. The measurements were performed in an ultracold sample via observation of the Autler-Townes splitting in a three-level ladder scheme, commonly used for 2-photon excitation of Rydberg states. To the best of our knowledge, this is the first systematic measurement of the electric dipole moments for transitions from low excited states of rubidium to Rydberg states. Due to its simplicity and versatility, this method can be easily extended to other transitions and other atomic species with little constraints. Good agreement of the experimental results with theory proves the reliability of the measurement method.Comment: 12 pages, 6 figures; figure 6 replaced with correct versio

State selective measurements of HCI produced by strong ultrashort laser clusters interaction

International audienceWe have performed studies of keV x-ray production from (Ar)n , (Kr)n and (Xe)n rare gas clusters (with n between 104 and 106 atoms/cluster) submitted to intense (~10^18 W/cm2) infrared (790 nm) laser pulses. We have determined the photon energies and the absolute photon emission yields as a function of several physical parameters governing the interaction : size and atomic number of the clusters, peak intensity of the laser. Up to 10^6 3 keV photons per pulse at a moderate (10^15/cm3) atomic density have been observed. High resolution spectroscopy studies in the case of (Ar)n clusters have also been performed, giving unambiguous evidence of highly charged (up to heliumlike) ions with K vacancies production. The results obtained indicate that X-rays are emitted before cluster explosion on a subpicosecond time scale, and shed some light on the mechanisms involved in the first stage of the production of the nanoplasma induced from each cluster