Monday, March 11, 2002 - DPG-Tagungen

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Nuclear Physics Tuesday In this talk we discuss the possible application of new reconstruction techniques in nuclear physics experiments. Furthermore the problem of generalisation and implementation in other fields such as medical imaging will be discussed. As an application we present the status of ongoing work with planar low energy x-ray images obtained at small stereo angles. HK 14.24 Tue 10:30 Foyer Chemie Performance of the CERES TPC — •H. Appelshaeuser 1 and A. Marin 2 for the CEREScollaboration — 1 Physikalisches Institut der Universität Heidelberg — 2 Gesellschaft für Schwerionenforschung mbH In 1998 the CERESspectrometer was upgraded by the addition of a large cylindrical Time Projection Chamber (TPC) operated inside the field of a new magnet system to provide momentum measurement. Key issue is the improvement in mass resolution in the ρ/ω/φ region to ∆m/m < 2%. The TPC adds also to the electron identification capability via dE/dx. Furthermore, the TPC opens the possibility of reconstructing the φ meson through its K + K − decay channel. The operation of a radial drift TPC inside an inhomogeneous magnetic field requires a very detailed understanding of the underlying electric and magnetic field configurations, drift properties for the Ne:CO2 (80:20) gas mixture, and detector geometry. We present the status of the TPC calibration and discuss the present performance. HK 14.25 Tue 10:30 Foyer Chemie Laboratory High Speed DAQ — •F. Karstens, A. Danasino, H. Fischer, J. Franz, A. Günemeier, S. Hedicke, F.H. Heinsius, M. v. Hodenberg, W. Kastaun, K. Königsmann, J. Reymann, T. Schmidt, H. Schmitt, andJ. Worch —Fakultät für Physik der Universität Freiburg, Hermann-Herder-Str. 3, D-79104 Freiburg. Hitherto data acquisition systems in laboratories were characterized by flexible setups, but slow data rates. High data rates are mainly realized in fixed setups at large accelerator experiments. This poster presents a solution, which involves both - high data rates and flexible usability. The DAQ of the COMPASS-Experiment at CERN has been adapted for laboratory purpose with two additional modules - a trigger-logiccontroller and a trigger-distributor - substituting the sophisticated trigger system. In our system trigger signals are generated by a programmable combinatoric logic in a VME-module using modern FPGA technology. Alternatively the module can be used as a programmable prescaler. The second module, realized in NIM-standard, provides a fan out for the trigger signals and the experiment clock. It interfaces to the existing DAQ, in particular to the Freiburg CATCH-module. The DAQ system is scalable and conveniently adjustable to different inputs due to exchangeable mezzanine cards, what makes it interesting for a variety of experiments. For further information: http://hpfr02.physik.uni-freiburg.de/projects/compass/electronics This project is supported by BMBF. HK 14.26 Tue 10:30 Foyer Chemie Development of the ALICE TRD Radiator — •Damian Bucher for the ALICE-TRD collaboration — Institut für Kernphysik, Westfälische Wilhelms-Universität, Münster, Germany In this poster we present the design and tests of the radiator for the ALICE Transition Radiation Detector (TRD). The ALICE TRD consists of 540 individual detector modules which cover an overall area of about 750 m 2 . Individual modules, which consist out of a radiator followed by a drift chamber, have entrance windows with a maximum size of about 1.2 ∗ 1.6 m 2 which are covered by the radiators. The radiator for this detector not only has to give a very good transition radiation yield but also acts as one of the main mechanical supporting structures of the detector modules. The crucial goal is to keep the entrance windows, which serve as the cathodes of the drift chambers, within the tolerated deflection of 1 mm. To achieve this, various materials were evaluated during several test beamtimes and checked for their mechanical properties. The requirements for the radiator resulting from the detector design as well as the final foam/fibre sandwich construction are presented. HK 14.27 Tue 10:30 Foyer Chemie A new Data Acquisition System for COSY TOF ∗ — •A. Erhardt 1 , M. Drochner 2 , T. Sefzick 2 ,andP. Wuestner 2 for the COSY-TOF collaboration — 1 Physikalisches Institut der Universität Tübingen — 2 Forschungszentrum Jülich Driven by the need for a faster data acquisition and implementation of the delayed-pulse technique for π + identification by use of multihit TDCs, the TOF collaboration decided to build a new data acquisition system. The experiment messaging system (EMS) has been chosen for several reasons: The system is successfully in use at several other experiments at COSY and the know-how is nearby since the system has been designed by people working at the Forschungszentrum Jülich. The new DAQ has been installed before the August 2001 beamtime and has been successfully used in that beamtime. This contribution shows how the different components cooperate, how compatibility with the collaborations’ data analysis demands will be assured, and which further developments are planned. ∗ supported by BMBF (06 TÜ 987) and DFG (European Graduate School) HK 14.28 Tue 10:30 Foyer Chemie LED-Flashers for the TOF detectors — •I. Martin, P. Grabmayr, T. Hehl, andJ. Heim — Physikalisches Institut, Univ. Tübingen For the detection of neutrons at intermediate energies the time-of-flight method employing fast scintillation counters is the only one which provides sufficient resolution for precision studies. A pulser system with Light Emitting Diodes has been developed for calibration, adjustment and surveillance during data taking. This system has been improved recently with blue ultra-bright LEDs. The electronic and mechanical redesign will be presented. Results from bench test will be shown as well as the performance during data taking at the (γ,NN) experiments at MAMI will be discussed. [1] T. Hehl al., Nucl. Instr. Meth. A354 (1995) 505 This work is supported by the DFG (European Graduate School Basel- Tübingen and SPP 1034) HK 14.29 Tue 10:30 Foyer Chemie The Nuclear Polarization of Molecules from Recombined Polarized Hydrogen and Deuterium Gas Atoms — •Hellmut Seyfarth 1 , Ralf Engels 2 , Peter Kravtsov 3 , Bernd Lorentz 1 , Maxim Mikirtytchiants 1,3 , Hans Paetz gen. Schieck 2 , Frank Rathmann 1 , Hans Ströher 1 , Nikolay Tchernov 3 ,andAlexandre Vassiliev 3 — 1 Institut für Kernphysik, Forschungszentrum Jülich, 52425 Jülich, Germany — 2 Institut für Kernphysik, Universität zu Köln, 50937 Köln, Germany — 3 High Energy Physics Department, St. Petersburg Nuclear Physics Institute, 188300 Gatchina, Russia During the past decade, polarized atomic H and D storage-cell gas targets have been successfully applied at storage rings. However, a fraction of the polarized atoms recombines in wall collisions. The nuclear polarization, of the molecules is not directly accessible with a Breit-Rabi polarimeter (as used at HERMES), only the polarization of the atoms extracted from the cell can be measured. In order to overcome the resulting systematic uncertainty in the total overall nuclear polarization of the target gas, the nuclear polarization of recombined H2 molecules was recently studied in a separate experiment [1]. A high value has been found for a strong external magnetic holding field. In the framework of an ISTC project [2], additional investigations of polarized hydrogen and new studies of polarized deuterium molecules are being prepared. These will also include different hyperfine state compositions and variation of the storing conditions like material and dimensions of the cell walls. [1] T. Wise et al., Phys. Rev. Lett. 87, 042701 (2001). [2] International Science and Technology Center, project no. 1861. HK 14.30 Tue 10:30 Foyer Chemie Study of the liquid hydrogen jet properties at the ANKE pellet target — •P. Fedorets 1 , V. Balanutsa 1 , W. Borgs 2 , M. Büscher 2 , A. Bukharov 3 , V. Chernetsky 1 , V. Chernyshov 1 , M. Chumakov 1 , A. Gerasimov 1 , V. Goryachev 1 , L. Gusev 1 , Z. Khorguashvili 4 , and S. Podchasky 1 for the ANKE collaboration — 1 ITEP, Moscow — 2 Forschungszentrum Jülich — 3 MPEI, Moscow — 4 IPH GAS, Tbilisi A pellet target will be utilized at the ANKE spectrometer to reach highest luminosities with a hydrogen pellet jet crossing the stored, circulating COSY beam. One of the main experimental tasks is to produce a stable liquid hydrogen jet, which will further be broken into microdroplets of about 50 µm diameter by acoustic excitation and finally freeze into pellets. Special care has to be taken about the jet-production boundary conditions. For this purpose jet modifications close to the triple-point (T =14K,p = 100 mbar) were studied, since only there stable jet can be generated. The status of the ANKE pellet target and the results of
Nuclear Physics Tuesday the hydrogen jet investigations will be presented. HK 14.31 Tue 10:30 Foyer Chemie Beam Properties of the ANKE Atomic Beam Source — •Alexandre Vassiliev1 , Reinhard Emmerich2 , Ralf Engels2 , Vladimir Koptev1 , Peter Kravtsov1 , Jürgen Ley2 , Bernd Lorentz3 , Stefan Lorenz4 , Maxim Mikirtytchiants1,3 , Mikhail Nekipelov1,3 , Hans Paetz gen. Schieck2 , Frank Rathmann3 , Hellmut Seyfarth3 , Erhard Steffens4 , and Hans Ströher3 — 1High Energy Physics Department, Petersburg Nuclear Physics Institute, 188300 Gatchina, Russia — 2Institut für Kernphysik, Universität zu Köln, 50937 Köln, Germany — 3Institut für Kernphysik, Forschungszentrum Jülich, 52425 Jülich, Germany — 4Physikalisches Institut II, Friedrich-Alexander Universität, 91058 Erlangen, Germany The polarized atomic beam source (ABS) will be utilized to feed the storage-cell gas target in future experiments at the magnetic spectrometer ANKE. The ABSproduces an intensity of (6.9 ± 0.3) · 1016 hydrogen atoms/s in two hyperfine substates, measured with a compression tube having the dimensions of the feeding tube of the storage-cell and installed at its position. For future polarization studies and experiments with polarized internal gas targets a Lamb-shift polarimeter, built at the University of Cologne, has been installed at the ABS. First measurements of the nuclear polarization of the atomic hydrogen beam yield Pz =0.889 ± 0.009. In addition, measurements of the degree of dissociation and of the beam profile at the position of the storage cell feeding tube will be discussed. HK 14.32 Tue 10:30 Foyer Chemie Calibration of a Compton polarimeter in a wide energy range∗ — C. Hutter1 , •D. Galaviz1 , K. Sonnabend1 , T. Hartmann1 , P. Mohr1 , W. Rochow2 , K. Vogt1 , S . Volz1 , and A. Zilges1 — 1Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstraße 9, D-64289 Darmstadt — 2Physikalisches Institut, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen A fourfold segmented High Purity Germanium detector can be used as Compton-polarimeter [1] in order to derive parities from photon scattering experiments. In order to calibrate the analyzing power of the polarimeter, (p, pγ), (p, αγ), and (α, γ) reactions have been studied in detail. We present a complete set of results up to a γ energy of 10 MeV. [1] B. Schlitt et al., Nucl. Instr. and Meth. in Phys. Res. A337 (1994) 416 ∗ supported by DFG (Zi 510/2-1 und FOR 272/2-1) HK 14.33 Tue 10:30 Foyer Chemie Ergebnisse der Streukorrektur für die PET bei der Schwerionentherapie — •Falk Pönisch und Wolfgang Enghardt — Forschungszentrum Rossendorf e.V., Postfach 510<strong>11</strong>9, 01314 Dresden Die Behandlung von Tumourpatienten mit 12 C-IonenwirdanderGSI Darmstadt seit Dezember 1997 durchgeführt. Bei der Dosisapplikation entstehen durch Wechselwirkung des Therapiestrahls mit dem bestrahlten Gewebe β + -emittierende Nuklide. Ihre räumliche Verteilung kann online mit dem am Strahl befindlichen Doppelkopf PET Scanner nachgewiesen werden. Voraussetzung für eine retrospektive Kontrolle der Dosislokalisation ist die Rekonstruktion der Radioaktivitätsverteilung aus den Messdaten mit Hilfe eines Maximum Likelihood Expectation Maximization (MLEM) Algorithmus. Die Comptonstreuung der Annihilationsphotonen im Gewebe des Patienten beeinträchtigt die Abbildungstreue der rekonstruierten Verteilung erheblich; deshalb sind die Messdaten dagegen zu korrigieren. Die vom Strahlentherapeuten verordnete Dosis bestimmt die Zählstatistik der PET-Studien. Die Zahl der registrierten Ereignisse liegt 2 bis 3 Grössenordnungen unter der in der Nuklearmedizin üblichen. Deswegen sind die dort ausgearbeiteten Verfahren der Streukorrektur auf PET bei der Schwerionentherapie nicht anwendbar und so wurde ein Verfahren der Streukorrektur in den MLEM-Rekonstruktionsalgorithmus integriert. Anhand der Rekonstruktionen von Phantom- und Patientenmessungen konnte die Richtigkeit der Methode bestätigt werden. HK 14.34 Tue 10:30 Foyer Chemie BunchlengthmeasurementsatELBE— •Pavel Evtushenko, Ulf Lehnert, Peter Michel, and Jochen Teichert — Forschungszentrum Rossendorf (FZR),Institut fuer Kern und Hadronenphysik,Postfach 510<strong>11</strong>9,01314 Dresden Last year the first ELBE accelerating module was commissioned. During the commissioning the electron beam parameters such as transverse emittance, energy spread and bunch length were measured. Each of them was studied at different bunch charges as a function of RF field phase in the first accelerating cavity. Especially for an accelerator like ELBE, which is intended to be a driver for free electron laser (FEL), bunch length measurement in picosecond range becomes very important and impose some challenge. Coherent transition radiation (CTR) technique was used to measure bunch length. This technique uses the Martin-Puplett interferometer to measure the autocorrelation of the CTR pulse yielding a minimum 2 ps RMSbunch length at 77pC bunch charge. Short description of the method, experimental setup, data evaluation procedure and results of the measurements will be presented. HK 14.35 Tue 10:30 Foyer Chemie Investigation of light spots and related field emission at the S–DALINAC ⋆ — •M. Gopych, W. Beinhauer, M. Brunken, H.- D. Gräf, T. Hartmann, M. Hertling, S.Kostial, U. Laier, A. Lenhardt, M. Platz, A. Richter, B. Schweizer, A. Stascheck, O. Titze, andS.Watzlawik—Inst.für Kernphysik, TU Darmstadt, Schlossgartenstr. 9, 64289 Darmstadt Above certain field thresholds spots of light associated with field emission have been observed on the surface of an RF niobium superconducting cavity at the S–DALINAC. The spectrum of the optical radiation has been measured by an spectrometer set up on axis at the beam line exit of the accelerator. It shows a sharp peak at 693 nm and three small ones at about 670 nm, 705 nm, and 714 nm. Measurements of field dependence and intensity of the light spots revealed a behaviour similar to the electroluminescence phenomenon. Additional results of measurements aiming at the investigation of the emission of light and related field emission performed at the superconducting cavities will be presented. ⋆ Supported by the DFG (FOR 272/2-1 and GRK 410/2) HK 14.36 Tue 10:30 Foyer Chemie Trigger and Readout for the Auger-Fluorescence telescopes — •Andreas Kopmann, Hermann-Josef Mathes, Hartmut Gemmeke, Matthias Kleifges, Alexandre Menshikov, and Denis Tcherniakhovski — Institut f”ur Prozessdatenverarbeitung und Elektronik, Forschungszentrum Karlsruhe The Pierre Auger Collaboration started with the construction of the first hybrid detector in Argentina. In the final state this experiment will consist of a large array of Cerenkov water detectors and 30 fluorescence telescopes to observe fluorescence light of EAS(Extensive air shower) with energies above 10 18 eV. Each telescope will be equipped with an independent trigger and readout system. The combination of fast hardware based pattern recognition and special software algorithms provide a trigger rate of a few events per hour. Since October 2001 two of this camera systems are operational. They demonstrate the power of the realized concept. The actual implemented trigger algorithms and their efficiency as well as the first data are presented. HK 14.37 Tue 10:30 Foyer Chemie ROOT-based off-line and on-line analysis of COSY-TOF data ∗ — •Martin Schulte-Wissermann and Leonhard Karsch for the COSY-TOF collaboration — Institut für Kern- und Teilchenphysik, TU Dresden, Germany The COSY-TOF spectrometer is used to study proton-proton collisions with up to 2.5 GeV kinetic energy. During an experiment which lasts typically several weeks data in the order of 100 GB are stored on tape. Due to the modular setup of the detector, which is optimized for each individual experiment, the data analysis software has to be adapted accordingly. Using ROOT as the fundamental framework, we have developed a strategy (set of rules) how to efficiently combine the contributions of all collaborators involved in the data analysis. We provide interfaces, data containers, and function libraries which are easy to use, robust, and well documented. The application of these tools in the analysis of COSY- TOF data will be demonstrated. The usefullness of the whole concept in the on-line supervision and calibration was shown during a recent run. ∗ Supported by BMBF and FZJ.
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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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