Ultra-Low-Power Superconductor Logic

We have developed a new superconducting digital technology, Reciprocal Quantum Logic, that uses AC power carried on a transmission line, which also serves as a clock. Using simple experiments we have demonstrated zero static power dissipation, thermally limited dynamic power dissipation, high clock stability, high operating margins and low BER. These features indicate that the technology is scalable to far more complex circuits at a significant level of integration. On the system level, Reciprocal Quantum Logic combines the high speed and low-power signal levels of Single-Flux- Quantum signals with the design methodology of CMOS, including low static power dissipation, low latency combinational logic, and efficient device count.Comment: 7 pages, 5 figure

Analytical calculation of the smear for long-range beam-beam interactions

The Lie-algebraic method is used to develop generalized Courant-Snyder invariant in the presence of an arbitrary number of beam-beam collisions, head-on or long-range, in a storage ring collider. The invariant is obtained by concatenating nonlinear beam-beam maps in the horizontal plane and to first order in the beam-beam parameter. Tracking evidence is presented to illustrate that with LHC parameters the invariant is indeed preserved and can be used to predict the smear of horizontal emittance observed in tracking simulations. We discuss the limits of applicability of this model for realistic LHC collision schemes

Results of dynamic aperture studies for increased beta* with beam-beam interactions

We have evaluated the dynamic aperture in the presence of beam-beam effects for alternative running scenarios, in particular for the commissioning and early operation of the LHC. For top energy of 7 TeV we have studied the effect of increased beta* up to beta* = 2 m and found the expected increase of dynamic aperture for a moderate loss of luminosity. We have further studied the possibility of head-on collisions with a small number of bunches at injection energy

Mode spectrum and temporal soliton formation in optical microresonators

The formation of temporal dissipative solitons in optical microresonators enables compact, high repetition rate sources of ultra-short pulses as well as low noise, broadband optical frequency combs with smooth spectral envelopes. Here we study the influence of the resonator mode spectrum on temporal soliton formation. Using frequency comb assisted diode laser spectroscopy, the measured mode structure of crystalline MgF2 resonators are correlated with temporal soliton formation. While an overal general anomalous dispersion is required, it is found that higher order dispersion can be tolerated as long as it does not dominate the resonator's mode structure. Mode coupling induced avoided crossings in the resonator mode spectrum are found to prevent soliton formation, when affecting resonator modes close to the pump laser. The experimental observations are in excellent agreement with numerical simulations based on the nonlinear coupled mode equations, which reveal the rich interplay of mode crossings and soliton formation

On the 2d Zakharov system with L^2 Schr\"odinger data

We prove local in time well-posedness for the Zakharov system in two space dimensions with large initial data in L^2 x H^{-1/2} x H^{-3/2}. This is the space of optimal regularity in the sense that the data-to-solution map fails to be smooth at the origin for any rougher pair of spaces in the L^2-based Sobolev scale. Moreover, it is a natural space for the Cauchy problem in view of the subsonic limit equation, namely the focusing cubic nonlinear Schroedinger equation. The existence time we obtain depends only upon the corresponding norms of the initial data - a result which is false for the cubic nonlinear Schroedinger equation in dimension two - and it is optimal because Glangetas-Merle's solutions blow up at that time.Comment: 30 pages, 2 figures. Minor revision. Title has been change

Large Scale Beam-beam Simulations for the CERN LHC using Distributed Computing

We report on a large scale simulation of beam-beam effects for the CERN Large Hadron Collider (LHC). The stability of particles which experience head-on and long-range beam-beam effects was investigated for different optical configurations and machine imperfections. To cover the interesting parameter space required computing resources not available at CERN. The necessary resources were available in the LHC@home project, based on the BOINC platform. At present, this project makes more than 60000 hosts available for distributed computing. We shall discuss our experience using this system during a simulation campaign of more than six months and describe the tools and procedures necessary to ensure consistent results. The results from this extended study are presented and future plans are discussed

Distribution and variability of dissolved hydrogen in the Mediterranean Sea

Hydrogen is one of the most interesting of the oceanic reduced gases because of its important role in both microbial nitrogen fixation and the anaerobic microbial food chain. A recent investigation in the Mediterranean Sea and Gulf of Cadiz on the USNS Bartlett has confirmed previous studies showing warm ocean waters to be supersaturated relative to atmospheric equilibrium in the mixed layer and undersaturated at depth...

LHC On-Line Model

The LHC machine will be a very demanding accelerator from a beam control perspective. There are tight constraints on the key beam parameters in the presence of large non-linearities and dynamic persistent current effects. Particle loss in the LHC must be actively minimized to avoid damage to the machine. Therefore any adjustment to the machine parameters would ideally be checked beforehand with a proper modeling tool. The LHC On-Line Model is an attempt to provide such an analysis tool based mainly on the MAD-X code. The goal is not to provide a real-time interactive system to control the LHC, but rather a way to speed up interaction with the power of MAD-X and to facilitate off-line analysis to give results within appropriate time constraints. There will be a rich spectrum of potential applications such as closed orbit correction, beta-beating analysis, optimization of non-linear correction and knob settings. We report the status of the on-line model software which is at present being developed for the beginning of the LHC commissioning