Search

The PANDA (AntiProton Annihilations at Darmstadt) experiment is being built at the new Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany. PANDA will measure antiproton-proton annihilation reactions in the charm quark mass range to investigate the nature of the strong interaction. This particle physics experiment will run at very high reaction rates of 10–20 MHz. Our work is related to an ADC (analog-to-digital converter) based data acquisition system for the PANDA Straw Tube Tracker (STT). The STT will be able to deliver data rates up to 20 GByte/s through over 4600 signal channels and could require major efforts for the hardware implementation as well as high offline processing power. Test beam studies were carried out in order to specify a proper system architecture with feasible hardware and to reduce output data stream to a level suitable for offline processing. We analyze the straw tube response to both the proton beam and ^55Fe irradiation. Furthermore, we present real-time processing using the neighboring straw information and introduce the technique to reconstruct the tracks. [ABSTRACT FROM PUBLISHER]

Frozen microspheres of hydrogen (pellets) will be one of the target types for the future hadron physics experiment PANDA at FAIR (GSI, Darmstadt, Germany) []. Pellets with a diameter of 25- μm are generated about 3 meters above the interaction region, to which they travel with a velocity around 80 m/s inside a narrow pipe. The interaction region is defined by the overlap of the pellet stream and the accelerator beam and has a size of a few millimeters. One would like to know the interaction point more precisely, to have better possibilities to reconstruct particle tracks and events e.g. in charmonium decay studies. One would also like to suppress background events that do not originate in a pellet, but e.g. may occur in rest gas, that is present in the beam pipe. A solution is provided by the presented pellet tracking system together with a target operation mode that provides one and only one pellet in the interaction region most of the time. The goal is to track individual pellets in order to know their position with a resolution of a few tenths of a millimeter at the time of an interaction. The system must also be highly efficient and provide tracking information for essentially all pellets that pass the interaction region. Presented results from the design studies show that the goals can be fulfilled by this solution. [ABSTRACT FROM AUTHOR]

For the operation of the WASA (Wide Angle Shower Apparatus) detector system at the Cooler Synchrotron COSY in Forschungszentrum Julich (FZJ) a new DAQ system has been developed, which conforms to the third generation of the DAQ systems at COSY. This comprises new readout electronics based on an optimized parallel bus with LVDS technology and FPGA-controlled event and buffer management. The new DAQ system has been successfully commissioned in autumn 2006. Further developments aiming at performance optimizations are in progress. The implementation status is presented and performance issues are discussed. [ABSTRACT FROM AUTHOR]

Wide angle shower apparatus (WASA), a detector for charged and neutral particles is currently operated at the CELSIUS storage ring by TSL, Uppsala University. It shall be transferred to the Cooler Synchrotron (COSY) at Forschungszentrum Jülich (FZJ) after the anticipated shutdown of CELSIUS in summer 2005. For operation in Jülich a new DAQ system is being developed, which conforms to the third generation of the DAQ systems at COSY. This comprises new readout electronics based on an optimized parallel bus with LVDS technology and FPGA-controlled event and buffer management, a synchronization system and a high speed optical link to the readout computer. Architecture of the new DAQ system and the technical issues of subsystems are presented. [ABSTRACT FROM AUTHOR]

Exclusive measurements of the two-pion production channel pp → ppπ+π- have been carried out near threshold at CELSIUS with the PROMICE/WASA detector. They reveal pp → pp* (1440) → ppσ → pp(π+ π- as the dominant process at these energies, however, the data exhibit also significant contributions from p*(1440) → Δπ → p(π+π-)I=l=0. From the observed interference of these Roper decay routes their relative branching ratio is derived. The status on the search for NN-decoupled NNπ-resonances is reviewed with regard to recent experimental searches in the pionic double charge exchange in nuclei, the two-pion production in nucleon-nucleon collisions, the photo pion-production on the deuteron and the electro pion-production in nuclei. [ABSTRACT FROM AUTHOR]

Presents information on a study which investigated rare decays of light mesons using the Wide Angle Shower Apparatus Data Acquisition System. Description of the first and second level trigger; Details on the event-building; Focus of the third level triggers; Development of the slow control systems.

We report on the first exclusive measurement of the 2 π production in NN collisions at T =750 MeV using a H cluster jet target and the WASA/PROMICE detector at CELSIUS. In the invariant-mass spectrum $$M_{pp\pi ^ - } $$ we observe a narrow peak at 2.063(2) GeV with a 4 σ deviation relative to the MC simulations for the conventional nonresonant 2 π production process. The finding is in agreement with the hypothesis of a narrow πNN resonance with I(J)=even (0), called d′, postulated recently to describe the peculiar resonance-like behavior of the pionic double charge exchange on nuclei. [ABSTRACT FROM AUTHOR]

The ABC effect, a low-mass enhancement in the invariant ππ mass, is observed in double-pionic fusion reactions leading to a bound nuclear system in the final state. From previous measurements there have been indications that this phenomenon is resctricted to the σ channel of the ππ system. With exclusive measurements of the pp → dπ+π0 reaction at Tp = 1.1 GeV we demonstrate that, indeed, the ABC effect does not occur in the vector-isovector ππ channel (ρ channel) despite the fact that the ΔΔ excitation is oberved to be the dominant reaction process. We also show that this reaction is well described by a t-channel ΔΔ excitation with the subsequent decay into the vector-isovector ππ channel given by the ρ channel operator. [ABSTRACT FROM AUTHOR]