A phenomenological analysis of antiproton interactions at low energies

We present an optical potential analysis of the antiproton-proton interactions at low energies. Our optical potential is purely phenomenological, and has been parametrized on data recently obtained by the Obelix Collaboration at momenta below 180 MeV/c. It reasonably fits annihilation and elastic data below 600 MeV/c, and allows us for an evaluation of the elastic cross section and rho-parameter down to zero kinetic energy. Moreover we show that the mechanism that depresses antiproton-nucleus annihilation cross sections at low energies is present in antiproton-proton interactions too.Comment: 10 pages, 4 figure

The high-intensity hyperon beam at CERN

A high-intensity hyperon beam was constructed at CERN to deliver Sigma- to experiment WA89 at the Omega facility and operated from 1989 to 1994. The setup allowed rapid changeover between hyperon and conventional hadron beam configurations. The beam provided a Sigma-flux of 1.4 x 10^5 per burst at mean momenta between 330 and 345 Gev/c, produced by about 3 x 10^10 protons of 450 GeV/c . At the experiment target the beam had a Sigma-/pi- ratio close to 0.4 and a size of 1.6 x 3.7 cm^2. The beam particle trajectories and their momenta were measured with a scintillating fibre hodoscope in the beam channel and a silicon microstrip detector at the exit of the channel. A fast transition radiation detector was used to identify the pion component of the beam.Comment: 20 pages, 13 figures. Submitted to Nucl. Instr. Meth.

Measurement of the Omega_c Lifetime

We present the measurement of the lifetime of the Omega_c we have performed using three independent data samples from two different decay modes. Using a Sigma- beam of 340 GeV/c we have obtained clean signals for the Omega_c decaying into Xi- K- pi+ pi+ and Omega- pi+ pi- pi+, avoiding topological cuts normally used in charm analysis. The short but measurable lifetime of the Omega_c is demonstrated by a clear enhancement of the signals at short but finite decay lengths. Using a continuous maximum likelihood method we determined the lifetime to be tau(Omega_c) = 55 +13-11(stat) +18-23(syst) fs. This makes the Omega_c the shortest living weakly decaying particle observed so far. The short value of the lifetime confirms the predicted pattern of the charmed baryon lifetimes and demonstrates that the strong interaction plays a vital role in the lifetimes of charmed hadrons.Comment: 15 pages, including 7 figures; gzipped, uuencoded postscrip

Coulomb corrections to low energy antiproton annihilation cross sections on protons and nuclei

We calculate, in a systematic way, the enhancement effect on antiproton-proton and antiproton-nucleus annihilation cross sections at low energy due to the initial state electrostatic interaction between the projectile and the target nucleus. This calculation is aimed at future comparisons between antineutron and antiproton annihilation rates on different targets, for the extraction of pure isospin channels.Comment: 18 pages, 4 figures (latex format

Разработка информационной системы обеспечения мероприятий организации техническими средствами

Дипломная работа включает в себя: 125 с., 40 рис., 21 таблиц, 17 источников. Возрастающий объем поступающих данных и трудоемкость их обработки, возрастающая нагрузка на сотрудников, обусловили необходимость в информационной системе, позволяющей оперативно работать с поступающим потоком данных и осуществляющей поиск информации, хранящейся в базе данных. Данная работа посвящена проектированию и созданию информационной системы для проведения технических и организационных мероприятий в Администрации Томской Области. В рамках данной работы была создан программный продукт – информационная система по работе с базой данных для обеспечения и техническогоThesis consists of: 125, Figure 40, 21 tables, 17 sources... Increasing the volume of incoming data and the complexity of their treatment, increasing the load on the employees, led to the need for an information system allowing operatively to work with the incoming data stream and search for information stored in the database. This work is dedicated to the design and development of an information system for technical and organizational measures in the Tomsk Oblast Administration. As part of this work was to create a software product - information system for working with the database and to provide technical support for the activities

Elaia, Pergamon's maritime satellite:The rise and fall of an ancient harbour city shaped by shoreline migration

Throughout human history, communication and trade have been key to society. Because maritime trade facilitated the rapid transportation of passengers and freight at relatively low cost, harbours became hubs for traffic, trade and exchange. This general statement holds true for the Pergamenian kingdom, which ruled wide parts of today's western Turkey during Hellenistic times. Its harbour, located at the city of Elaia on the eastern Aegean shore, was used extensively for commercial and military purposes. This study reconstructs the coastal evolution in and around the ancient harbour of Elaia and compares the observed environmental modifications with archaeological and historical findings. We use micropalaeontological, sedimentological and geochemical proxies to reconstruct the palaeoenvironmental dynamics and evolution of the ancient harbour. The geoarchaeological results confirm the archaeological and historical evidence for Elaia's primacy during Hellenistic and early Roman times, and the city's gradual decline during the late Roman period. Furthermore, our study demonstrates that Elaia holds a unique position as a harbour city during ancient times in the eastern Aegean region, because it was not greatly influenced by the high sediment supply associated with river deltas. Consequently, no dredging of the harbour basins is documented, creating exceptional geo-bioarchives for palaeoenvironmental reconstructions

100% reflectivity from a monolithic dielectric microstructured surface

Here, we propose a new mirror architecture which is solely based upon a monolithic dielectric micro-structured surface. Hence, the mirror device, which consists of a possibly mono-crystalline bulk material, can in principle simultaneously provide perfect reflectivity and lowest mechanical loss. By specifically structuring the monolithic surface, resulting in T-shaped ridges of a subwavelength grating, a resonant behavior of light coupling can be realized, leading to theoretically 100% reflectivity

Monolithic dielectric surfaces as new low-loss light-matter interfaces

We propose a new mirror architecture, which is solely based upon structuring of the surface of a monolithic, possibly monocrystalline, bulk material. We found that a structure of T-shaped ridges of a subwavelength grating can theoretically provide 100% reflectivity. Since no material needs to be added to the mirror device, lowest mechanical loss can also be expected. Our approach might have compelling applications as a new light-matter interface

Telefoninterviews - ein alternatives Erhebungsverfahren? Ergebnisse einer Pilotstudie

Während in der Bundesrepublik telefonische Befragungen bislang nur selten zur sozialwissenschaftlichen Datenerhebung eingesetzt werden, ist in den USA schon seit einigen Jahren eine schrittweise Ablösung der mündlichen Befragungen mit persönlichen Interviews durch telefonische Erhebungen zu beobachten. Insbesondere die steigenden Kosten des persönlichen Interviews bedingen die wachsende Attraktivität der telefonischen Befragung. Um die Möglichkeiten eines verstärkten Einsatzes der neuen Methode unter den anderen Bedingungen der Bundesrepublik (geringere Telefondichte, anderes Tarifsystem als in den USA) zu ermitteln, führten die Verfasser im Januar 1981 in Mannheim eine Pilotstudie durch (standardisiertes Telefoninterview zu dem Thema der sozialen Konsequenzen eines Umzuges). Die Versuchsergebnisse (252 vollständige Interviews bei einer bereinigten Stichprobe von 600 Telefonteilnehmern) wurden mit den Ergebnissen einer amerikanischen Studie verglichen, bei der im August 1981 unter ähnlichen Bedingungen 250 Haushaltsvorstände telefonisch befragt worden waren. Der vorliegende Untersuchungsbericht beschreibt im einzelnen die Stichprobenziehung, die Arbeitsbedingungen der Interviewer, Interviewerauswahl und -schulung sowie Supervision und Feldkontrolle. Die wichtigsten Ergebnisse (Ausschöpfung der Stichprobe, soziodemographische Strukturmerkmale der Stichprobe, Einfluß der Erhebungszeit auf das Kontaktergebnis, Interviewerreaktionen) werden vorgestellt und in ihrer Unterschiedlichkeit gegenüber den amerikanischen Felddaten diskutiert. Besondere Berücksichtigung finden in dem Forschungsbericht die Spezialfragen Interviewereinflüsse und Zehner-Skala im Telefoninterview. In einer vorläufigen methodischen Beurteilung des neuen Verfahrens kommen die Verfasser durchweg zu ermutigenden Ergebnissen; sie weisen allerdings auf die Notwendigkeit hin, Probleme und Chancen näher zu erforschen. (JL