A 35 GHz solid state transmitter/driver

Solid state transmitter/driver /multiplier/ signal source has been designed and fabricated to produce a stable crystal-controlled CW power output of 100 mw at 35 GHz

Data Management and Mining in Astrophysical Databases

We analyse the issues involved in the management and mining of astrophysical data. The traditional approach to data management in the astrophysical field is not able to keep up with the increasing size of the data gathered by modern detectors. An essential role in the astrophysical research will be assumed by automatic tools for information extraction from large datasets, i.e. data mining techniques, such as clustering and classification algorithms. This asks for an approach to data management based on data warehousing, emphasizing the efficiency and simplicity of data access; efficiency is obtained using multidimensional access methods and simplicity is achieved by properly handling metadata. Clustering and classification techniques, on large datasets, pose additional requirements: computational and memory scalability with respect to the data size, interpretability and objectivity of clustering or classification results. In this study we address some possible solutions.Comment: 10 pages, Late

Light quark hadrons in hadronic Z decays

The results on the inclusive production of light quark hadrons in the hadronic decays of the Z are reviewed. Particular attention is paid to the new results on the inclusive production in Z -> bbbar events

Two topics in multiparticle dynamics at LEP: multiplicity in bb events and screwiness at the end of the QCD cascade

This talk deals with two topics in multiparticle dynamics investigated by means of the DELPHI detector at LEP. Related to the first topic, we have used the data collected at 183 GeV to measure the average charged particle multiplicity in e/sup +/e/sup -/ to bb events. The result is remarkably in agreement with QCD predictions, while it is more than two standard deviations larger than calculations assuming that the multiplicity accompanying the decay of a heavy quark is independent of the mass of the quark itself. The second topic deals with a recent theoretical model by Andersson et al. (1998), in which soft gluons order themselves in the form of a helix at the end of the QCD cascades. In our data at the Z peak, we have found no evidence for such an effect. (26 refs)

Very-high-energy gamma astrophysics

High-energy photons are a powerful probe for astrophysics and for fundamental physics under extreme conditions. During the recent years, our knowledge of the most violent phenomena in the Universe has impressively progressed thanks to the advent of new detectors for very-high-energy γ-rays. Ground-based detectors like the Cherenkov telescopes (H.E.S.S. and MAGIC in particular) recently discovered more than 70 new very-high-energy sources. This article reviews the present status of very-high-energy gamma astrophysics, with emphasis on the results related to fundamental physics and on the experimental developments

Neural networks for gamma-hadron separation in MAGIC

Neural networks have proved to be versatile and robust for particle separation in many experiments related to particle astrophysics. We apply these techniques to separate gamma rays from hadrons for the MAGIC Cerenkov Telescope. Two types of neural network architectures have been used for the classi cation task: one is the MultiLayer Perceptron (MLP) based on supervised learning, and the other is the Self-Organising Tree Algorithm (SOTA), which is based on unsupervised learning. We propose a new architecture by combining these two neural networks types to yield better and faster classi cation results for our classi cation problem.Comment: 6 pages, 4 figures, to be published in the Proceedings of the 6th International Symposium ''Frontiers of Fundamental and Computational Physics'' (FFP6), Udine (Italy), Sep. 26-29, 200