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A novel field-programmable gate array (FPGA)-based online tracking algorithm for helix track reconstruction in a solenoidal field, developed for the Antiproton Annihilations at Darmstadt spectrometer, is described. Employing the straw tube tracker detector with 4636 straw tubes, the algorithm includes a complex track finder and a track fitter. Implemented in VHDL, the algorithm is tested on a Xilinx Virtex-4 FX60 FPGA chip with different types of events, at different event rates. A processing time of 7~\mu \texts per event for an average of six charged tracks is obtained. The momentum resolution is about 3% (4%) for pt ( pz ) at 1 GeV/c. Comparing with the algorithm running on a CPU chip (single core Intel Xeon E5520 at 2.26 GHz), an improvement of three orders of magnitude in processing time is obtained. The algorithm can handle severe overlapping of events, which are typical for interaction rates above 10 MHz. [ABSTRACT FROM AUTHOR]

An Electron-ion collider in China (EicC) has recently been proposed, for imaging the precise and detailed internal structures of hadrons, understanding the emergent properties of nucleon (such as the nucleon mass and spin) and the emergence of nuclear medium effect, and studying the exotic hadronic states. By exploiting the abundant “pion cloud” around the proton, an experiment of measuring the pion structure is suggested, and it is one of the physics highlights at the EicC facility. In this paper, we present a simulation study of the proposed pion structure experiment. At EicC, the pion structure information is accessed via the leading-neutron tagged deep inelastic scattering—the widely acknowledged Sullivan process of pion exchange with small momentum transfer. We briefly discuss the theoretical framework of our event generator and the current design of the experimental setup for the experiment. We then evaluate the statistical errors of the pion structure function that would be extracted from the proposed measurement under the integrated luminosity of 50 fb - 1 . The sensitivity and precision to pion parton distribution functions are also demonstrated with a global fit. The precise quark distributions of the pion can be achieved at EicC in the range of 0.05 < x π < 0.95 , and the pion gluon distribution also can be constrained by the global fit of the pseudo-data at various Q 2 . [ABSTRACT FROM AUTHOR]

Abstract: The commissioning of the RPC-based muon detector in the BESIII experiment has been carried out. The RPC modules, front-end electronics, online and offline software of the muon system have been studied. The detector performances including efficiency, counting rate, noise ratio, spacial resolution, dark current, and muon charge ratio were obtained by cosmic ray data with and without magnetic field. The new operating high voltage and threshold were chosen after the scan experiment. The long-term stability of the BESIII RPCs made of bakelite without oil treatment was studied. [Copyright &y& Elsevier]