Evaluation of a wind-tunnel gust response technique including correlations with analytical and flight test results

A wind tunnel technique for obtaining gust frequency response functions for use in predicting the response of flexible aircraft to atmospheric turbulence is evaluated. The tunnel test results for a dynamically scaled cable supported aeroelastic model are compared with analytical and flight data. The wind tunnel technique, which employs oscillating vanes in the tunnel throat section to generate a sinusoidally varying flow field around the model, was evaluated by use of a 1/30 scale model of the B-52E airplane. Correlation between the wind tunnel results, flight test results, and analytical predictions for response in the short period and wing first elastic modes of motion are presented

Spin filling of a quantum dot derived from excited-state spectroscopy

We study the spin filling of a semiconductor quantum dot using excited-state spectroscopy in a strong magnetic field. The field is oriented in the plane of the two-dimensional electron gas in which the dot is electrostatically defined. By combining the observation of Zeeman splitting with our knowledge of the absolute number of electrons, we are able to determine the ground state spin configuration for one to five electrons occupying the dot. For four electrons, we find a ground state spin configuration with total spin S=1, in agreement with Hund's first rule. The electron g-factor is observed to be independent of magnetic field and electron number.Comment: 11 pages, 7 figures, submitted to New Journal of Physics, focus issue on Solid State Quantum Informatio

Evaluation of expected solar flare neutrino events in the IceCube observatory

Since the end of the eighties and in response to a reported increase in the total neutrino flux in the Homestake experiment in coincidence with a solar flare, solar neutrino detectors have searched for solar flare signals. Neutrinos from the decay of mesons, which are themselves produced in collisions of accelerated protons with the solar atmosphere, would provide a novel window on the underlying physics of the acceleration process. For our studies we focus on the IceCube Neutrino Observatory, a cubic kilometer neutrino detector located at the geographical South Pole. Due to its Supernova data acquisition system and its DeepCore component, dedicated to low energy neutrinos, IceCube may be sensitive to solar flare neutrinos and thus permit either a measurement of the signal or the establishment of more stringent upper limits on the solar flare neutrino flux. We present an approach for a time profile analysis based on a stacking method and an evaluation of a possible solar flare signal in IceCube using the Geant4 toolkit.Comment: Paper submitted to the 34th International Cosmic Ray Conference, The Hague 201

Decomposition of NO studied by infrared emission and CO laser absorption

A diagnostic technique for monitoring the concentration of NO using absorption of CO laser radiation was developed and applied in a study of the decomposition kinetics of NO. Simultaneous measurements of infrared emission by NO at 5.3 microns were also made to validate the laser absorption technique. The data were obtained behind incident shocks in NO-N2O-Ar (or Kr) mixtures, with temperatures in the range 2400-4100 K. Rate constants for dominant reactions were inferred from comparisons with computer simulations of the reactive flow

Measurement efficiency and n-shot read out of spin qubits

We consider electron spin qubits in quantum dots and define a measurement efficiency e to characterize reliable measurements via n-shot read outs. We propose various implementations based on a double dot and quantum point contact (QPC) and show that the associated efficiencies e vary between 50% and 100%, allowing single-shot read out in the latter case. We model the read out microscopically and derive its time dynamics in terms of a generalized master equation, calculate the QPC current and show that it allows spin read out under realistic conditions.Comment: 5 pages, 1 figur

Energy Dependent Tunneling in a Quantum Dot

We present measurements of the rates for an electron to tunnel on and off a quantum dot, obtained using a quantum point contact charge sensor. The tunnel rates show exponential dependence on drain-source bias and plunger gate voltages. The tunneling process is shown to be elastic, and a model describing tunneling in terms of the dot energy relative to the height of the tunnel barrier quantitatively describes the measurements.Comment: 4 pages, 4 figure

Real-time detection of single electron tunneling using a quantum point contact

We observe individual tunnel events of a single electron between a quantum dot and a reservoir, using a nearby quantum point contact (QPC) as a charge meter. The QPC is capacitively coupled to the dot, and the QPC conductance changes by about 1% if the number of electrons on the dot changes by one. The QPC is voltage biased and the current is monitored with an IV-convertor at room temperature. We can resolve tunnel events separated by only 8 $\mu$s, limited by noise from the IV-convertor. Shot noise in the QPC sets a 25 ns lower bound on the accessible timescales.Comment: 3 pages, 3 figures, submitte