The experiment BESIII, running at the accelerator BEPCII in Beijing (P.R.C.), is going to be updated with the replacement of the Inner Drift Chamber with a Cylindrical triple-GEM Inner Tracker ...(CGEM-IT). In the R&D stage, two standalone C++ codes were implemented: GTS (Garfield-based Triple-GEM Simulator), for digitization and tuning of simulated data to the experimental ones, and GRAAL (GEM Reconstruction And Analysis Library), for the reconstruction and analysis of the experimental events collected in testbeams. GTS simulates the triple-GEM response to the particle passage, treating each stage separately: ionization, GEM properties, gas mixture, magnetic field and finally the induction of the signal on the anode. The necessary information was extracted by GARFIELD++ simulations, parametrized and used as input in GTS. This speeds up the simulation, since GTS performs only samplings instead of the full digitization chain. The simulated events were reconstructed with the same procedure used for experimental data and tuning factors were evaluated to obtain a satisfactory match. GRAAL is used in the analysis of the testbeam experimental data. It provides several levels of reconstruction: from the cluster formation, gathering contiguous firing strips, to the spatial position and the signal time reconstruciton. Two algorithms are used: the charge centroid and the micro-TPC, which exploit the charge deposition on the strips and the time information. Also a merging of the two algorithms is available to efficiently weight the two outcomes and obtain the best estimate of the spatial coordinate. Moreover, GRAAL performs tracking and alignment. Both codes are going to be made available also for other MPGDs simulation and reconstruction.
The zero degree detector at BESIII Anelli, M.; Baldini Ferroli, R.; Bertani, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2013, Letnik:
718
Journal Article
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A small-size calorimeter has been built in the Frascati National Laboratory of INFN for BESIII detector based on the BEPCII storage ring of the Institute of High Energy Physics in Beijing. It has ...been installed in one of the two small-theta angle regions of BEPCII to measure the energy of photons from Initial State Radiation events and is currently taking data together with BESIII. The detector is a sandwich of Pb and scintillating fibers, the same technique employed for the KLOE calorimeter at the DAΦNE accelerator, but the readout is actuated by way of bundles of clear plastic fibers. We describe here the fabrication, present results from tests with cosmic rays and at the Frascati Beam Test Facility, the installation in BESIII, and preliminary luminosity measurements.
This paper examines individuals’ reactions to the prospect of gaining or losing status in groups. The results of three experiments provide evidence that individuals attach greater value to status ...when recalling the risk of status loss than when recalling the potential for status gain (Experiment 1), are willing to pay more to avoid a status loss than to achieve a status gain (Experiment 1), and put forth greater effort when striving to prevent status loss than when striving to gain status (Experiment 2). Finally, individuals who risk losing status allocate more resources toward personal status concerns (and away from group interests and potential monetary gain) than do individuals who have a chance of gaining status (Experiment 3). We discuss the implications of this research both in terms of individuals’ psychological experience of their status, as well as status attainment and maintenance concerns in groups.
The PANDA detector will be located at the future GSI accelerator FAIR. Its primary objective is the investigation of strong interaction with anti-proton beams, in the range up to 15 GeV/c as momentum ...of the incoming anti-proton. The PANDA offline simulation framework is called PandaRoot , as it is based upon the ROOT 5.14 package. It is characterized by a high versatility; it allows to perform simulation and analysis, to run different event generators (EvtGen, Pluto, UrQmd), different transport models (Geant3, Geant4, Fluka) with the same code, thus to compare the results simply by changing few macro lines without recompiling at all. Moreover auto-configuration scripts allow installing the full framework easily in different Linux distributions and with different compilers (the framework was installed and tested in more than 10 Linux platforms) without further manipulation. The final data are in a tree format, easily accessible and readable through simple clicks on the root browsers. The presentation will report on the actual status of the computing development inside the PandaRoot framework, in terms of detector implementation and event reconstruction.
We present a search for the e+e− decay of a hypothetical dark photon, also named U vector boson, in inclusive dielectron spectra measured by HADES in the p(3.5 GeV) + p, Nb reactions, as well as the ...Ar (1.756 GeV/u) + KCl reaction. An upper limit on the kinetic mixing parameter squared ϵ2 at 90% CL has been obtained for the mass range MU=0.02–0.55 GeV/c2 and is compared with the present world data set. For masses 0.03–0.1 GeV/c2, the limit has been lowered with respect to previous results, allowing now to exclude a large part of the parameter region favored by the muon g−2 anomaly. Furthermore, an improved upper limit on the branching ratio of 2.3×10−6 has been set on the helicity-suppressed direct decay of the eta meson, η→e+e−, at 90% CL.