Search

We study the backscattering of solar wind protons from the lunar regolith using the Solar Wind Monitor of the Sub keV Atom Reflecting Analyzer on Chandrayaan 1. Our study focuses on the component of the backscattered particles that leaves the regolith with a positive charge. We find that the fraction of the incident solar wind protons that backscatter as protons i.e. the proton backscattering efficiency has an exponential dependence on the solar wind speed that varies from 0.01 to 1 for solar wind speeds of 250 km/s to 550 km/s. We also study the speed distribution of the backscattered protons in the fast (550 km/s) solar wind case and find both a peak speed at 80 of the solar wind speed and a spread of 85 km/s. The observed flux variations and speed distribution of the backscattered protons can be explained by a speed dependent charge state of the backscattered particles.

Accepted: 2014-01-12, 資料番号: SA1140003000

Accepted: 2013-05-09, 資料番号: SA1004623000

The formation of electric potential over lunar magnetized regions is essential for understanding fundamental lunar science, for understanding the lunar environment, and for planning human exploration on the Moon. A large positive electric potential was predicted and detected from single point measurements. Here, we demonstrate a remote imaging technique of electric potential mapping at the lunar surface, making use of a new concept involving hydrogen neutral atoms derived from solar wind. We apply the technique to a lunar magnetized region using an existing dataset of the neutral atom energy spectrometer SARA/CENA on Chandrayaan-1. Electrostatic potential larger than +135 V inside the Gerasimovic anomaly is confirmed. This structure is found spreading all over the magnetized region. The widely spread electric potential can influence the local plasma and dust environment near the magnetic anomaly., 19 pages, 3 figures

We report the first observation of protons in the near (100--200 km from surface) and deeper (near anti-subsolar point) lunar plasma wake when the interplanetary magnetic field (IMF) and solar wind velocity ($v_{sw}$) are parallel (aligned flow, angle between IMF and ($v_{sw} \le 10^\circ$). More than 98% of the observations during aligned flow condition showed the presence of protons in the wake. These observations are obtained by the SWIM sensor of the SARA experiment on Chandrayaan-1. The observation cannot be explained by the conventional fluid models for aligned flow. Back-tracing of the observed protons suggests that their source is the solar wind. The larger gyro-radii of the wake protons compared to that of solar wind suggest that they were part of the tail of the solar wind velocity distribution function. Such protons could enter the wake due to their large gyro-radii even when the flow is aligned to IMF. However, the wake boundary electric field may also play a role in the entry of the protons in to the wake., Comment: 4 pages, 4 figures

We present first measurements of energetic neutral atoms that originate from solar wind plasma having interacted with the lunar nightside surface. We observe two distinct energetic neutral atom (ENA) distributions parallel to the terminator, the spectral shape, and the intensity of both of which indicate that the particles originate from the bulk solar wind flow. The first distribution modifies the dayside ENA flux to reach ~6° into the nightside and is well explained by the kinetic temperature of the solar wind protons. The second distribution, which was not predicted, reaches from the terminator to up to 30° beyond the terminator, with a maximum at ~102° in solar zenith angle. As most likely wake transport processes for this second distribution we identify acceleration by the ambipolar electric field and by the negatively charged lunar nightside surface. In addition, our data provide the first observation indicative of a global solar zenith angle dependence of positive dayside surface potentials.

The Sub keV Atom Reflecting Analyzer instrument on board the lunar orbiter Chandrayaan 1 provided a large number of measurements of lunar energetic neutral atoms (ENAs). These ENAs were formerly solar wind ions which were neutralized and backscattered from the lunar surface. The angles under which the ENAs are scattered strongly depend on the solar wind ions' incidence angle which corresponds to the solar zenith angle (SZA). Our large dataset provides us with a complete coverage of the SZA and almost complete coverage of the scattering angles. When combining all available measurements four distinct features are discernible with SZA increase: amplitude decrease less azimuthal uniformity bigger ratio of sunward versus anti sunward flux and shallower scattering. We analyzed more than 290'000 measurements and derived a mathematical description of the features and their dependencies on the SZA. Citation: Schaufelberger A. P. Wurz S. Barabash M. Wieser Y. Futaana M. Holmstrom A. Bhardwaj M. B. Dhanya R. Sridharan and K. Asamura (2011) Scattering function for energetic neutral hydrogen atoms off the lunar surface Geophys. Res. Lett. 38 L22202 doi:10.1029/2011GL049362.

資料番号: PAIS08049000

Context. The Rosetta spacecraft is escorting comet 67P/Churyumov-Gerasimenko from a heliocentric distance of >3.6 AU, where the comet activity was low, until perihelion at 1.24 AU. Initially, the solar wind permeates the thin comet atmosphere formed from sublimation. Aims. Using the Rosetta Plasma Consortium Ion Composition Analyzer (RPC-ICA), we study the gradual evolution of the comet ion environment, from the first detectable traces of water ions to the stage where cometary water ions accelerated to about 1 keV energy are abundant. We compare ion fluxes of solar wind and cometary origin. Methods. RPC-ICA is an ion mass spectrometer measuring ions of solar wind and cometary origins in the 10 eV–40 keV energy range. Results. We show how the flux of accelerated water ions with energies above 120 eV increases between 3.6 and 2.0 AU. The 24 h average increases by 4 orders of magnitude, mainly because high-flux periods become more common. The water ion energy spectra also become broader with time. This may indicate a larger and more uniform source region. At 2.0 AU the accelerated water ion flux is frequently of the same order as the solar wind proton flux. Water ions of 120 eV–few keV energy may thus constitute a significant part of the ions sputtering the nucleus surface. The ion density and mass in the comet vicinity is dominated by ions of cometary origin. The solar wind is deflected and the energy spectra broadened compared to an undisturbed solar wind. Conclusions. The flux of accelerated water ions moving from the upstream direction back toward the nucleus is a strongly nonlinear function of the heliocentric distance.

The goal of molecular electronics is the realization of integrated molecular circuits. For this purpose reliable contacts to single molecules have to be built and the characteristics of those junctions need to be investigated. We have demonstrated that the mechanically controllable break junction (MCBJ) technique is a suitable tool to study the electrical transport through molecular junctions and to analyze the electronic structure of the molecules. Furthermore, based on the use of complex molecules, we are able to control the conductance of single molecular junctions. On the one hand, molecular switches are transformed in-situ from a non-conductive “off”- to a conductive ”on”-state via light-irradiation of a well-defined wavelength. On the other hand molecule-metal complexes are turned from an isolating to a conductive state by introducing metal centers into the molecular structures. The findings provide a significant contribution to the development of functional molecular junctions.

In this paper we present the results of the last stage of the research project Empower Daphne that involved the participation of six countries belonging to the EU in two phases: I) validation of the theoretical model on which basis rests the construct of well-being and spontaneity; II) analysis of Morenian psychodrama intervention efficacy. 407 university students were part of the non-clinical sample in the first phase and 136 women victims of domestic violence made up the clinical sample for the second phase. During the six month the women took part in psychodramatic sessions, together with individual interviews. At the beginning and the end of the six month, a questionnaire was administered consisting of a well-being and a spontaneity scales. In the article we present the results that compare well-being and spontaneity between clinical and non-clinical samples, and between the clinical cut-off scores highlighted in the literature and the scores of clinical sample. The findings demonstrate interesting differences between two sample: observed lower levels of spontaneity and well-being in women victims of domestic violence, both before and after the psychodramatic intervention., La camera blu, Vol 10, N° 11 (2014): Against gender-based violence: from Italian debate to intercultural dialogue

The lunar surface is very efficient in reflecting impinging solar wind ions as energetic neutral atoms (ENAs). A global analysis of lunar hydrogen ENAs showed that on average 16% of the solar wind protons are reflected, and that the reflected fraction can range from less than 8% to more than 24%, depending on location. It is established that magnetic anomalies reduce the flux of backscattered hydrogen ENAs by screening-off a fraction of the impinging solar wind. The effects of the surface properties, such as porosity, roughness, chemical composition, and extent of weathering, were not known. In this paper, we conduct an in-depth analysis of ENA observations of the South Pole-Aitken basin to determine which of the surface properties might be responsible for the observed variation in the integral ENA flux. The South Pole-Aitken basin with its highly variable surface properties is an ideal object for such studies. It is very deep, possesses strikingly elevated concentrations in iron and thorium, has a low albedo and coincides with a cluster of strong magnetic anomalies located on the northern rim of the basin. Our analysis shows that whereas, as expected, the magnetic anomalies can account well for the observed ENA depletion at the South Pole-Aitken basin, none of the other surface properties seem to influence the ENA reflection efficiency. Therefore, the integral flux of backscattered hydrogen ENAs is mainly determined by the impinging plasma flux and ENA imaging of backscattered hydrogen captures the electrodynamics of the plasma at the surface. We cannot exclude minor effects by surface features. (C) 2015 Elsevier Ltd. All rights reserved.

Der unter dem Namen Social Construction of Technology oder kurz „SCOT“ bekannt gewordene Ansatz wurde in den 1980er und frühen 1990er Jahren gemeinsam von dem britischen Soziologien Trevor Pinch und dem niederländischen Technikforscher Wiebe Bijker entwickelt. In Absetzung von den bis dahin dominierenden internalistisch-technikhistorischen oder innovationsökonomisch orientierten Arbeiten zur Technikentwicklung, plädierten die beiden Autoren für eine kontextualistische Betrachtungsweise, die technische Artefakte sowohl als Erzeugnisse wie als Erzeuger kontingenter sozialer Handlungs- und Deutungszusammenhänge interpretiert. Kennzeichnend für diesen Ansatz war ein Analysestil der detaillierte, meist historische, Fallstudien exemplarischer technischer Artefakte, mit der Entwicklung allgemeiner theoretischer Kategorien verband. Durch die Kumulation und vergleichende Kontrastierung solcher Fallstudien sollten nicht nur Einsichten in die soziale und politische Dynamik technischer Innovationsprozesse gewinnon werden, sondern ein auch angemesseneres Verständnis entwickelter Gesellschaften als „technologischer Kulturen“ (Bijker 1995: 288). Das Kapitel beschreibt und diskutiert die Entwicklung des SCOT-Ansatzes von seiner ersten Formulierung durch Bijker und Pinch im Jahre 1987 bis hin zu seiner Weiterentwicklung in einer Reihe technikspezifischer Fallstudien.

A major goal of molecular electronics is the development and implementation of molecular electronic devices such as single molecular switches. In this work we present a detailed study of single diarylethene molecules that were in situ switched from their non-conductive to conductive state in the presence of gold nanoelectrodes via controlled light irradiation. The molecules were dissolved in two different solvents and measured with two different side-groups. Histograms of conductance traces were taken and complemented by extracting the relative position of the current carrying molecular level and its level broadening from current-voltage characteristics by means of the single level transport model. The obtained results show a clear light-induced ring forming isomerization, which is almost independent of the side-groups, while electron withdrawing side groups lead to a reduction of conductance, a decrease of the level broadening and an increased difference between the molecular level and the Fermi energy of the metals. Quantum chemical calculations of the light-induced switching processes correlate these observations with the fundamentally different low-lying electronic states of the opened and closed forms and their comparably small modification by the electron-withdrawing substituents.

Molecular electronics has been a eld of big interest for the last years. Using the technique of mechanically controllable break junctions we characterize the Switchable Molecular Wire Oligo(phenylene ethynylene)-embedded Difurylperuorocyclopentenes (SMW) in liquid environment. Via light irradiation the SMW can be switched between two well-defined conductance states. Conductance and hysteresis measurements allow us to identify the two states providing the basis for a comprehensive study of the in situ switching process. Based on the analysis with the transport model assuming transport through a single molecular level, we confirm that a reliable contact of the molecules to the gold contacts is formed and extract the energy of the molecular levels and the coupling constants between molecule and electrodes.