Azimuthal Angular Distributions in EDDE as Spin-Parity Analyser and Glueball Filter for LHC

Exclusive Double Diffractive Events (EDDE) are analysed as the source of information about the central system. Experimental possibilities for exotic particles searches are considered. From the reggeized tensor current picture some azimuthal angle dependences were obtained to fit the data from WA102 experiment and to make predictions for LHC collider.Comment: LaTeX, 20 pages, 7 figures, references are adde

Case Study of Non-Isolated MMC DC-DC Converter in HVDC Grids

Peer reviewedPublisher PD

Antimatter and Matter Production in Heavy Ion Collisions at CERN (The NEWMASS Experiment NA52)

Besides the dedicated search for strangelets NA52 measures light (anti)particle and (anti)nuclei production over a wide range of rapidity. Compared to previous runs the statistics has been increased in the 1998 run by more than one order of magnitude for negatively charged objects at different spectrometer rigidities. Together with previous data taking at a rigidity of -20 GeV/c we obtained 10^6 antiprotons 10^3 antideuterons and two antihelium3 without centrality requirements. We measured nuclei and antinuclei (p,d,antiprotons, antideuterons) near midrapidity covering an impact parameter range of b=2-12 fm. Our results strongly indicate that nuclei and antinuclei are mainly produced via the coalescence mechanism. However the centrality dependence of the antibaryon to baryon ratios show that antibaryons are diminished due to annihilation and breakup reactions in the hadron dense environment. The volume of the particle source extracted from coalescence models agrees with results from pion interferometry for an expanding source. The chemical and thermal freeze-out of nuclei and antinuclei appear to coincide with each other and with the thermal freeze-out of hadrons.Comment: 12 pages, 8 figures, to appear in the proceedings of the conference on 'Fundamental Issues in Elementary Matter' Bad Honnef, Germany, Sept. 25-29, 200

Modular modelling of combined AC and DC systems in dynamic simulations

A formulation is proposed in which an AC-DC system is modeled as a combination of AC grids, DC grids, injectors, AC two-ports and AC/DC converters, respectively. This modular modelling facilitates the dynamic simulation of future complex AC/DC systems. Furthermore, it can be exploited by the solver, which performs less operations on components with lower dynamic activity, and offers parallel processing of the time simulation. This approach is illustrated on a test system in which a multi-terminal DC grid connects two asynchronous AC systems, allows frequency support between them, and acts as emergency control against AC voltage instability

Assessment of interoperability in multi-vendor VSC-HVDC systems : interim results of the Best Paths DEMO #2

This paper describes the methodology and interim results from the ongoing European project Best Paths DEMO #2, which is the first attempt to undertake systematic investigation on interoperability in multi-vendor VSC-HVDC systems. The study is based on state-of-the-art technologies provided by three world-class HVDC vendors and involves TSOs and academics for investigations covering various HVDC layouts, from point-to-point to radial and meshed multi-terminal structures. The paper describes the methodology used to assess and maximize interoperability, which comprises two stages: the first one relies on electromagnetic transient (EMT) simulation tools, while the second and ongoing one relies on real-time simulation with actual control cubicles provided by HVDC vendors. The paper mainly reports on the different tasks which were carried out during the first stage (EMT simulations) and exhibits the results observed. The main tasks and results are listed as follows: - Commonly agreed definition of interoperability - Definition of common converter specifications for all involved HVDC vendors, based on the ENTSO-E Network Code for realism and replicability - Definition of 5 different DC systems (including DC grids) on which interoperability should be assessed - Provision of detailed vendor-specific EMT converter models, and their individual validation - Assessment of interoperability on more than 1.000 realistic scenarios, from which 15% are representative of actual interoperability issues between the vendors - First set of recommendations to maximize interoperability Finally, the paper provides insights on the second and ongoing stage of the project based on real-time simulation using actual vendor control cubicles for deeper investigations

Charged pion production in fixed target Pb + Pb collisions at 158 GeV per nucleon

Changes in pion production as a function of the impact parameter of the collision or the incident energy, may reveal characteristics of a possible first-order phase transition from nuclear to quark matter, as predicted by lattice quantum chromodynamics. In this paper we investigate charged pion production in Pb+Pb collisions at 158 GeV/nucleon near 0° production angle and at forward rapidity $(4.3\leq y \leq 6.3)$. The centrality dependence of pion production is shown in the impact parameter range ~ 2-12 fm at the rapidities y = 5.7 and 6.3. An enhancement in the pi-/pi+ ratio has been measured near beam rapidity, indicating Coulomb interaction of charged pions with the spectator protons. The charged pion yield per nucleon participating in the collision (N_p) at y = 5.7 increases faster than linearly with N_p, up to N_p~100 and then it saturates, while at y = 6.3 it does not exhibit any sudden change as a function of N_p