Monday, March 11, 2002 - DPG-Tagungen

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Nuclear Physics Tuesday tigated for several reaction systems studied at beam energies between 40 and 150 AMeV during the INDRA@GSI campaign. The observed dependence of the source size on the impact parameter and on the collision partners agree well with the expectations for the reaction geometry. HK 13.4 Tue 10:30 Foyer Chemie Pions in Spectator Fragmentation Induced by Relativistic 12 C Projectiles — •Ketel Turzó for the ALADIN-INDRA collaboration — GSI Darmstadt, Planckstr. 1, D-64291 Darmstadt As part of the INDRA@GSI campaign in 1998/1999, fragmentation in asymmetric systems like 12 C+ 197 Au and 12 C+ <strong>11</strong>2,124 Sn was studied at bombarding energies ranging from 95 to 1800 AMeV. At angles θlab ≥ 45 ◦ , particle detection and identification with high resolution was achieved with the Si-Si-CsI(Tl) calibration telescopes of the INDRA multidetector system, including the identification of charged pions. Delta and pion production and absorption represent an efficient heating mechanism in collisions at relativistic energies. The present data permit the study of correlations between pion and fragment emissions, i.e. between emissions reflecting properties of the primary heating phase of the collision and of the subsequent decay of a highly equilibrated spectator system. First results, indicating an anticorrelation between the multiplicities of pions and intermediate-mass fragments for lower spectator excitations, will be presented. HK 13.5 Tue 10:30 Foyer Chemie Particle Intensities at the GSI Secondary Beam Facility — •M. Ardid 1 , J. Diaz 1 , A. Andronic 2 , A. Banu 2 , O. Busch 2 , M. Gersabeck 2 ,andR.S. Simon 2 — 1 Institut de Física Corpuscular, Universitat de València and Centro Superior de Investigaciones Científicas, E-46071 València, Spain — 2 Gesellschaft für Schwerionenforschung, D- 64291 Darmstadt, Germany Using protons and 12 Cand 14 N ions from the 18 Tm heavy–ion synchrotron SIS, secondary beams of electrons and pions are produced and delivered to the experimental areas in the SIS target hall. We discuss the production mechanism in the pencil–like thick target rods and address the transport performance of the beam lines as well as the impact of diagnostic detectors for monitoring and precise momentum definition. Mixed π − /e − beams with momenta between 0.5 and 2.0 GeV/c have been extensively used for prototype tests of the ALICE Transition Radiation Detector, while π + beams around 1 GeV/c with maximum intensity and optimal π + /p ratio are required for physics runs at the HADESand Kaon Spectrometer. HK 13.6 Tue 10:30 Foyer Chemie Λ - Production in C+C Reactions at 158 AGeV* — •I. Kraus 1 , L. Betev 2 , A. Billmeier 1 , C. Blume 1 , R. Bramm 2 , P. Buncic 2 , P. Dinkelaker 2 , M. Ga´zdzicki 2 , T. Kollegger 2 , C. Markert 3 , R. Renfordt 2 , A. Sandoval 1 , R. Stock 2 , H. Ströbele 2 , D. Vranić 1 , A. Wetzler 2 ,andJ. Zaranek 2 for the NA49 collaboration — 1 GSI, Darmstadt — 2 Institut für Kernphysik, Frankfurt — 3 Yale, New Haven, USA The number of hyperons (Λ) per participating nucleon is higher in A+A than in p+p collisions [1]. It is interesting to measure the detailed behavior of hyperon production as a function of the system size in order to determine the onset of this type of strangeness enhancement. NA49 has taken data not only on Pb+Pb but also C+C collisions. The results from the light C+C system are compared to earlier measurements of Λ hyperons in central S+S (NA35), central Pb+Pb and p+p interactions. [1] A.Mischke et al. (NA49 Collab.), Proceedings of the 6th International Conference on Strangeness in Quark Matter 2001 * Supported by GSI and BMBF HK 13.7 Tue 10:30 Foyer Chemie Production of φ → e + e − in central Pb+Pb collisions at 158AGeV ∗ — •Peter Dinkelaker 1 , L. Betev 1 , C. Blume 2 , R. Bramm 1 , P. Buncic 1 , M. Ga´zdzicki 1 , T. Kollegger 1 , I. Kraus 2 , A. Mischke 2 , R. Renfordt 1 , A. Sandoval 2 , R. Stock 1 , H. Ströebele 1 , D. Vranic 1 , A. Wetzler 1 ,andJ. Zaranek 1 for the NA49 collaboration — 1 Institut für Kernphysik, Universität Frankfurt — 2 Gesellschaft für Schwerionenforschung, Darmstadt The first results on φ → e + e − production in central Pb+Pb collisions at 158 AGeV are presented. They are based on the NA49 data (3 million events) taken in the dedicated run in 2000. The obtained upper limit estimate for the φ yield is compared with the results for the hadronic decay channel φ → K + K − measured in NA49 and for the leptonic decay channel φ → µ + µ − measured in NA50. A review of models concerning φ production and possible differences between results obtained from leptonic and hadronic decay channels is given. ∗ supported by BMBF and GSI HK 13.8 Tue 10:30 Foyer Chemie Calibration and charged particle distributions of the Forward- TPCs in the STAR Experiment — •Jörn Putschke, Volker Eckardt, Andreas Gärtner, Gaspare Lo Curto, Markus Oldenburg, Patrizia Krok, Maria Mora, Andreas Schüttauf, Norbert Schmitz, Janet Seyboth, Peter Seyboth, Frank Simon, and Michael Vidal — Max-Planck-Institut für Physik, Föhringer Ring 6, 80805 München The two Forward-TPCs, designed and constructed at the Max-Planck- Institut für Physik in Munich, expand the overall acceptance of the STAR detector at the Relativistic Heavy Ion Collider (RHIC) to the pseudorapidity region 2.5 < |η| < 4. Due to the high multiplicity of approximatly 500 charged particle in each Forward-TPC in a central Au+Au collisions at √ sNN = 200 GeV, a radial drift configuration perpendicular to the magnetic field was choosen to improve the two-track separation. To calibrate the drift velocity and the � E × � B corrections in the nonuniform radial drift field a laser calibration system was used. In contrast to a standard configuration TPC a good measurement of the drift velocity is essential to accurately determine the spatial positions of the hit clusters and to precisely determine the momenta of the charged particles. Preliminary results will be discussed on the charged particle distributions and the baryon number flow as difference in the distributions of positively and negatively charged particle as a function of η. HK 13.9 Tue 10:30 Foyer Chemie The role of three-body collisions in φ mesonproduction processes near threshold in heavy-ion reactions — •H.W. Barz 1 , B. Kämpfer 1 , M. Zetenyi 2 ,andGy. Wolf 2 — 1 FZ Rossendorf, D-01314 Dresden — 2 KFKI Budapest, H-1525 Budapest The amplitude of subthreshold φ meson production is calculated using dominant tree-level diagrams for three-body collision. It is shown that the production can overwhelmingly be described by two consecutive twostep processes, i.e. the cross section factorises in two sub-cross-sections with an intermediate on-shell particle. As a consequence to desribe the production of heavy mesons within transport models all intermediate particles have to be included in the calculations. The effect is demonstrated in calculating φ production in heavy-ion collisions at bombarding energies around 2 GeV per nucleon as recently measured by the FOPI collaboration. Including elementary ρ − N, ρ − ∆andπ − ρ collisions the calculated production rates increase by about a factor of three compared to earlier calculations which do not include these channels. Momentum spectra of φ mesons and dilepton spectra which are accessible in future HADESand FOPI experiments are given. HK14 Poster Session: Instrumentation and Applications Time: Tuesday 10:30–12:45 Room: Foyer Chemie HK 14.1 Tue 10:30 Foyer Chemie Quantitative analysis of lepton induced Cherenkov rings in a CsI based RICH — •L. Fabbietti, T. Eberl, J. Friese, R. Gernhäuser, J. Homolka, H.-J. Körner, M. Münch, B. Sailer, and S. Winkler for the HADEScollaboration — Technische Universität München, James-Franck-Strasse 1,D-85748 Garching A Monte-Carlo based understanding of the lepton induced Cherenkov ring recognition in the RICH detector is crucial for the whole lepton identification in the HADESspectrometer. A dedicated measurement was performed which allows to study the response of the RICH detector to the photon signal. The results of these studies were used to optimize the digitasation procedure for the RICH detector, in order to achieve a good agreement between real and simulated data for the heavy ion reaction environment.
Nuclear Physics Tuesday A set of full GEANT simulations of the HADESspectrometer, using UrQMD and thermal sources as input, was analysed and compared to the experimental data for the reaction C+C@1.5AGeV and Cr+Al@1.5AGeV. The quantitative evaluation of these comparisons will be presented. ∗ supported by BMBF (6TM970I) and GSI (TM-FR1). HK 14.2 Tue 10:30 Foyer Chemie Impact of the calibration of the HADES drift chambers on the quality of the tracking — •Peter Zumbruch for the HADEScollaboration — GSI, Gesellschaft für Schwerionenforschung, Darmstadt, Germany HADES, a High Acceptance DiElectron Spectrometer, is a second generation experiment at the GSI SIS facility in Darmstadt. Its scientific program includes studies of in-medium properties of hadrons in hadronic matter and the electromagnetic structure of hadrons. High quality tracking is needed to provide a high invariant mass resolution (1 background. In the HADESsetup a high precision tracking is performed by two pairs of two multiwire drift chamber (MDC) modules in front and behind of the toroidial magnet field. The quality of the tracking is mainly affected by the performance and the alignment of the individual chambers as well as the accuracy of the drift time measurements. Hence, precise time calibration strategies - developed with data and simulation - are essential to meet the ambitious design goals of HADES. supported by GSI, BMBF, DFG, INTAS, EC HK 14.3 Tue 10:30 Foyer Chemie The HADES Run Control ∗ — •B. Sailer, T. Eberl, L. Fabbietti, J. Friese, R. Gernhäuser, J. Homolka, H.-J. Körner, M. Münch, andS. Winkler — Technische Universität München, James- Franck-Strasse 1, D-85748 Garching The new High Acceptance DiElectron Spectrometer HADES has been setup at GSI Darmstadt and is now ready to take data. The ATM-based data aquisition together with a multilevel trigger system will be able to read out 70 000 channels with a first level trigger rate of 10 5 Hz with zero supression and transport 1−2×10 3 events to mass storage every second. To operate this complex system consists of more than 1 000 frontend and over 100 VME boards with a large number of different tasks and layouts, a run control system based on the EPICSpackage has been developed making use of its network communication layer, monitoring capabilities and sequencing. In particular an interface has been developed that allows to bring several thousand parameters from different sources to the run control system and to write back status information to a database. The layout of the system will be presented. ∗ supported by BMBF (6TM970I) and GSI (TM-FR1). HK 14.4 Tue 10:30 Foyer Chemie Programmable Downscalers and Dead-Time Measurement for HADES — •D. Schäfer, I. Fröhlich, A. Gabriel, D. Kirschner, W. Kühn, J. Lehnert, M. Petri, J. Ritman, A. Toia, andM. Traxler for the HADEScollaboration — II. Physikalisches Institut Universität Giessen, Heinrich-Buff-Ring 14, 35392 Giessen The HADES-Spectrometer at GSI Darmstadt allows the production of dilepton pairs in hadron and heavy ion induced reactions up to 2 AGeV to be investigated. The trigger system (raw event rate 100 kHz) is designed to reduce the event rate by a factor of 100. The HADESTrigger system is a distributed modular system. It includes dedicated Detector Trigger Units for each detector subsystem which all communicate with the Central Trigger Unit (CTU) via the first and second level trigger bus. In order to accomodate a large variety of experiments the functionality of the CTU will be extended by an additional module. This module provides programmable downscaling and dead time measurement for each of the individual inputs. Dead-time measurements will be made by determining the rates before and after the downscaling for each input. The add-on will be implemented into a Field Programmable Gate Array (FPGA) to allow flexible configuration. HK 14.5 Tue 10:30 Foyer Chemie Concept for a Dedicated Multi-Node Data Processing System for Realtime Trigger and Analysis Applications — •D. Kirschner, I. Fröhlich, A. Gabriel, W. Kühn, J. Lehnert, M. Petri, J. Ritman, D. Schäfer, A. Toia, andM. Traxler —II. Phys. Inst. Giessen,, Heinrich-Buff-Ring 14, 35392 Giessen Modern Experiments in hadron physics like the HADESdetector at GSI-Darmstadt produce a large amount of data that has to be distributed, stored and analyzed. Analysis of this data is very time consuming due to the large amount of data and the complex algorithms needed. This problem can be addressed by a dedicated multi-node and multi- CPU computing architecture interconnected by Gigabit-Ethernet. Dedicated hardware has the advantages over “Grid-Computers” in skaleability, price per computational unit, predictability of time behavior (posibility of real time applications) and ease of administration. Gigabit- Ethernet provides an efficient and standardized infrastructure for data distribution. This infrastructure can be used to distribute data in an experiment as well as to distribute data in a multi-node computing environment. The concept of a prototype VME-Bus card for data distribution and analysis in a multi-node environment will be presented. The card will be divided into two major units: a network unit featuring two Gigabit Ethernet connections and a computational part featuring several Digital Signal Processors. HK 14.6 Tue 10:30 Foyer Chemie Status of the HADES detector alignment — •Alexandre Sadovski 1 , H. Agakichiev 2 , H. Alvarez-Pol 3 , I. Duran 3 , B. Fuentes 3 , J. A. Garzon 3 , W. König 2 , R. Kotte 1 , V. Pechenov 4 , M. Sanchez 3 ,andP. Zumbruch 2 for the HADEScollaboration — 1 Forschungszentrum Rossendorf, Institut für Kern- und Hadronenphysik, Dresden, Germany — 2 GSI Darmstadt, Germany — 3 Universidade de Santiago de Compostela, Spain — 4 Joint Institute of Nuclear Research, Dubna, Russia The accurate determination of the masses of various vector mesons decaying into e + e − pairs is among the physics goals of the starting HADES experiments at SIS/GSI Darmstadt. This requires an overall invariant mass resolution of about 1 %. To achieve the corresponding momentum resolution a precise knowledge of the detector position is needed. A common way to do this is to correct (align) for possible deviations from the nominal positions using calibration data and the knowledge of the detector’s geometry. Several alignment procedures have been developed and tested using tracks from data on heavy-ion collisions aquired during several data taking periods. Alignment corrections for the multiwire drift chamber (MDC) positions have been found. Checks for MDC alignments have been developed and successfully applied. The methods and results used will be presented and surveyed. HK 14.7 Tue 10:30 Foyer Chemie A client - server based online monitoring system based on ROOT,QT and OpenGL for the use in the HADES experiment. — •Jörn Wüstenfeld for the HADEScollaboration — Johann - Wolfgang Goethe Universität Frankfurt, Institut für Kernphysik August-Euler-Stra¨se 6 D-60486 Frankfurt / M Even though the prices for CPU’s and memory are low, no experiment has ever enought computing power available. Therefore new techniques for the online/offline analysis have to be developed. One possible way is to use a client - server model, where the computing intensive part is done on one central machine with fast CPU’s and big memory, while the displaying task is hosted by decentral machines with less computing power. Following this concept, a monitoring system has been implemented in the HADESanalysis framework. Besides basic functionalities it provides global detector performace monitoring and a 3D eventdisplay of HADES. The talk will present the conceptual design of the monitoring system and a demonstration of the achieved monitor capabilities. This work was supported by GSI, BMBF, DFG, INTAS, EC. HK 14.8 Tue 10:30 Foyer Chemie Datenaufbereitung und -analyse für das A4-Experiment an MAMI — •Sebastian Baunack für die A4-Kollaboration — Institut für Kernphysik, Johannes-Gutenberg-Universität Mainz, 55099 Mainz Das totalabsorbierenden Bleifluorid-Kalorimeter des A4-Experimentes an MAMI zur Messung der Paritätsverletzung in der elastischen Streu-
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Page 65 and 66: Nuclear Physics Friday HK49 Plenary
Page 67 and 68: M. Ding3 , M.O. Distler3 , P. Drago
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Page 75 and 76: Friese, J. . HK 14.1, HK 14.3, HK 4
Page 77 and 78: Rusev, G. ..................HK 10.1

Monday, March 11, 2002 - DPG-Tagungen

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