A high-speed optical star network using TDMA and all-optical demultiplexing techniques

The authors demonstrate the use of time-division multiplexing (TDM) to realize a high capacity optical star network. The fundamental element of the demonstration network is a 10 ps, wavelength tunable, low jitter, pulse source. Electrical data is encoded onto three optical pulse trains, and the resultant low duty cycle optical data channels are multiplexed together using 25 ps fiber delay lines. This gives an overall network capacity of 40 Gb/s. A nonlinear optical loop mirror (NOLM) is used to carry out the demultiplexing at the station receiver. The channel to be switched out can be selected by adjusting the phase of the electrical signal used to generate the control pulses for the NOLM. By using external injection into a gain-switched distributed feedback (DFB) laser we are able to obtain very low jitter control pulses of 4-ps duration (RMS jitter <1 ps) after compression of the highly chirped gain switched pulses in a normal dispersive fiber. This enables us to achieve excellent eye openings for the three demultiplexed channels. The difficulty in obtaining complete switching of the signal pulses is presented. This is shown to be due to the deformation of the control pulse in the NOLM (caused by the soliton effect compression). The use of optical time-division multiplexing (OTDM) with all-optical switching devices is shown to be an excellent method to allow us to exploit as efficiently as possible the available fiber bandwidth, and to achieve very high bit-rate optical networks

Final-Focus System for CLIC at 3 TeV

We describe a base-line optics for a 3-TeV final-focus system of the Compact Linear Collider (CLIC). The proposed system consists of an initial beta-matching region, two chromatic correction sections, and a final transformer, and it provides a total demagnification by a factor 90 horizontally and 346 vertically. The length per side amounts to 3.3 km. The effect of synchrotron radiation and higher-order aberrations is minimised by an odd dispersion function in the chromatic correction section. For a total flat energy spread of 1%, the system promises a luminosity of about 80% of the ideal. The 20-30% spot-size dilutions in the two transverse planes reflect a trade-off between the Oide effect and higher-order chromo-geometric aberrations

A time-Frequency Application with the Stokes-Woodward technique

In a recent paper, we have generalized Woodward's theorem and applied it to the case of random signals jointly modulated in amplitude and frequency. This generalization yields a new spectral technique to estimate the amount of energy due to mode coupling without calling for higher-order statistics. Two power spectra are detected; the first is related to the independent modes and the second contains extra energy caused by mode coupling. This detection is now extended from frequency to timefrequency domain. A comparison between a wavelet transform and our time-frequency technique shows good agreement along with new insight into the time occurrence of the nonlinearities or mode coupling. Application to water surface waves is given in this letter as an example

CLIC simulations from the start of the linac to the interaction point

Simulations for linear colliders are traditionally performed separately for the different sub-systems, like damping ring, bunch compressor, linac, and beam delivery. The beam properties are usually passed from one sub-system to the other via bunch charge, RMS transverse emittances, RMS bunch length, average energy and RMS energy spread. It is implicitly assumed that the detailed 6D correlations in the beam distribution are not relevant for the achievable luminosity. However, it has recently been shown that those correlations can have a strong effect on the beam-beam interaction. We present first results on CLIC simulations that integrate linac, beam delivery, and beam-beam interaction. These integrated simulations also allow a better simulation of time-dependent effects, like ground perturbations and interference between several beam-based feedbacks

Potential of herbariomics for studying repetitive DNA in angiosperms

Repetitive DNA has an important role in angiosperm genomes and is relevant to our understanding of genome size variation, polyploidisation and genome dynamics more broadly. Much recent work has harnessed the power of high-throughput sequencing (HTS) technologies to advance the study of repetitive DNA in flowering plants. Herbarium collections provide a useful historical perspective on genome diversity through time, but their value for the study of repetitive DNA has not yet been explored. We propose that herbarium DNA may prove as useful for studies of repetitive DNA content as it has for reconstructed organellar genomes and low-copy nuclear sequence data. Here we present a case study in the tobacco genus (Nicotiana; Solanaceae), showing that herbarium specimens can provide accurate estimates of the repetitive content of angiosperm genomes by direct comparison with recently-collected material. We show a strong correlation between the abundance of repeat clusters, e.g., different types of transposable elements and satellite DNA, in herbarium collections versus recent material for four sets of Nicotiana taxa. These results suggest that herbarium specimen genome sequencing (herbariomics) holds promise for both repeat discovery and analyses that aim to investigate the role of repetitive DNAs in genomic evolution, particularly genome size evolution and/or contributions of repeats to the regulation of gene space

Status of the CLIC study on magnet stabilisation and time-dependent luminosity

The nanometer beam size at the CLIC interaction point imposes magnet vibration tolerances that range from 0.2 nm to a few nanometers. This is well below the floor vibra-tion usually observed. A test stand for magnet stability was set-up at CERN in the immediate neighborhood of roads, operating accelerators, manual shops, and regular office space. It was equipped with modern stabilization tech-nology. First results are presented, demonstrating signif-icant damping of floor vibration. CLIC quadrupoles have been stabilized vertically to an rms motion of (0.9 ± 0.1) n above 4 Hz, or (1.3 ± 0.2) nm with a nominal flow of cooling water. For the horizontal and longitudinal directions respectively, a CLIC quadrupole was stabilized to (0.4 ± 0.1) nm and (3.2 ± 0.4) nm

Studies of New Vector Resonances at the CLIC Multi-TeV e+e- Collider

Several models predict the existence of new vector resonances in the multi-TeV region, which can be produced in high energy e+e- collisions in the s-channel. In this paper we review the existing limits on the masses of these resonances from LEP/SLC and TEVATRON data and from atomic parity violation in some specific models. We study the potential of a multi-TeV e+e- collider, such as CLIC, for the determination of their properties and nature.Comment: 17 pages, 16 EPS figures, uses JHEP3.cl

The CLIC Study of Magnet Stability and Time-dependent Luminosity Performance

The present parameters of the CLIC study require the collision of small emittance beams with a vertical spot size of 1 nm. The tolerances on vertical quadrupole vi-bration (above a few Hz) are as small as a few nm in the linac and most of the Final Focus. The final focusing quadrupole has a stability requirement of 4 nm in the horizontal and 0.2 nm in the vertical direction. Those tol-erances can only be achieved with the use of damped support structures for CLIC. A study has been set-up at CERN to explore the application of stabilization devices from specialized industry and to predict the time-dependent luminosity performance for CLIC. The results will guide the specification of required technological im-provements and will help to verify the feasibility of the present CLIC parameters