126253177
Experimental measurement of the mass of the tau lepton at the Beijing Electron Positron Collider (BEPC)
122659739
The BES upgrade
Abstract The Beijing Spectrometer (BES) detector is a general purpose solenoid detector at the Beijing Electron Positron Collider (BEPC) in Beijing, China, that has collected large numbers of J/ψ, ψ′, D s , D and τ events. In this paper, we describe the recent upgrade of the initial BES detector (BESI) to the improved BESII detector.
125302092
Measurements of the line shapes of D anti-D production and the ratio of the production rates of D+ D- and D0 anti-D0 in e+ e- annihilation at psi(3770) resonance
Abstract We report measurements of the line shapes of D + D − , D 0 D ¯ 0 and D D ¯ production as well as the line shape of the ratio of the production rates of D + D − and D 0 D ¯ 0 in e + e − annihilation at ψ ( 3770 ) resonance. We find that the line shapes of D + D − , D 0 D ¯ 0 and D D ¯ production are similar to an anomalous line shape of cross sections for e + e − → hadrons observed in the center-of-mass energy range from 3.70 to 3.87 GeV.
126124755
Measurement of the internal spin structure of the proton
Our final results of measurements at SLAC of the spin dependent asymmetry in the deep inelastic scattering of longitudinally polarized electrons by longitudinally polarized protons are presented. Data were obtained at a scattering angle of 10° and for incident energies of 16.2 and 22.7 GeV, which cover the kinematic range 0.18<x<0.70 and 3.5<Q2<10.0 (GeV/c)2. We compare our results with various models of proton spin structure and with the Bjorken and Ellis‐Jaffe sum rules.
19719907
Trigger System of BESIII
The trigger system of Beijing Spectrometer III, part of the upgrade of Beijing Electron Positron Collider, has been designed and implemented, and is ready for installation. This paper describes briefly the system components, its characteristics, and some technical issues. The system consists mainly of four parts: MDC (drift chamber) tracking subsystem, EMC (electromagnetic calorimeter) subsystem, TOF (time of flight) subsystem and global trigger. Some highlights in designing of this system includes: trigger scheme optimization with software simulation; optical transmission between trigger and FEEs to realize isolation with FEEs to avoid ground loop current interference; designed with most latest FPGA (Xilinx Spartan 3, VirtexII Pro...) for simplicity, high reliability and easy maintenance and hence smaller system; FPGA in-system programming or firmware online downloadable via onboard, panel connector and/or VME bus for modification flexibility during commissioning. Different from the usual fix delay data transmission from FEE to trigger, the RocketIO has been used as SEDES.
182722222
First Level Trigger in the GEM Muon System
118582101
Fostering the adoption of GRID techniques: The case of the astroparticle physics experiment ARGO
The EUChinaGRID project is a FIX-funded initiative within the 6th Framework Programme, aiming at, disseminating advanced knowledge in Grid technologies, interconnecting the European and Chinese e-Infrastructures, and deploying existing and new Grid applications: the astroparticle physics experiment ARGO is One such application. This document will describe the strategy for the adoption of Grid techniques for data-manipulation activities within the ARGO experiment.
52994935
Identification of the TeV Gamma-ray Source ARGO J2031+4157 with the Cygnus Cocoon
The extended TeV gamma-ray source ARGO J2031+4157 (or MGRO J2031+41) is positionally consistent with the Cygnus Cocoon discovered by Fermi-LAT at GeV energies in the Cygnus superbubble. Reanalyzing the ARGO-YBJ data collected from 2007 November to 2013 January, the angular extension and energy spectrum of ARGO J2031+4157 are evaluated. After subtracting the contribution of the overlapping TeV sources, the ARGO-YBJ excess map is fitted with a two-dimensional Gaussian function in a square region of 10° × 10°, finding a source extension σ{sub ext}= 1.°8 ± 0.°5. The observed differential energy spectrum is dN/dE = (2.5 ± 0.4) × 10{sup –11}(E/1 TeV){sup –2.6±0.3} photons cm{sup –2} s{sup –1} TeV{sup –1}, in the energy range 0.2-10 TeV. The angular extension is consistent with that of the Cygnus Cocoon as measured by Fermi-LAT and the spectrum also shows a good connection with the one measured in the 1-100 GeV energy range. These features suggest to identify ARGO J2031+4157 as the counterpart of the Cygnus Cocoon at TeV energies. The Cygnus Cocoon, located in the star-forming region of Cygnus X, is interpreted as a cocoon of freshly accelerated cosmic rays related to the Cygnus superbubble. The spectral similarity with supernova remnants (SNRs) indicates thatmore » the particle acceleration inside a superbubble is similar to that in an SNR. The spectral measurements from 1 GeV to 10 TeV allows for the first time to determine the possible spectrum slope of the underlying particle distribution. A hadronic model is adopted to explain the spectral energy distribution.« less
118750093
Implications of the AMS-02 positron fraction in cosmic rays
The AMS-02 collaboration has just released its first result of the cosmic positron fraction e(+)/(e(-) + e(+)) with high precision up to similar to 350 GeV. The AMS-02 result shows the same trend with the previous PAMELA result, which requires extra electron/positron sources on top of the conventional cosmic ray background, either from astrophysical sources or from dark matter annihilation/decay. In this paper we try to figure out the nature of the extra sources by fitting to the AMS-02 e(+)/(e(-) + e(+)) data, as well as the electron and proton spectra by PAMELA and the (e(-) + e(+)) spectrum by Fermi and HESS. We adopt the GALPROP package to calculate the propagation of the Galactic cosmic rays and the Markov Chain Monte Carlo sampler to do the fit. We find that under the conventional assumptions about the background and the extra source of the e(-) + e(+), we cannot fit the AMS-02 and Fermi/HESS data well simultaneously. The AMS-02 data require less electrons/positrons from the extra sources than that required by Fermi/HESS. It may indicate that the model needs to be refined or the data between these experiments have systematic uncertainties. The pulsar scenario generally fits the data better than the DM scenario. Furthermore, the constraints from gamma-rays also disfavor the DM scenario to explain the cosmic ray lepton data. (C) 2014 Elsevier B.V. All rights reserved.
56081006
MEAN INTERPLANETARY MAGNETIC FIELD MEASUREMENT USING THE ARGO-YBJ EXPERIMENT
The Sun blocks cosmic-ray particles from outside the solar system, forming a detectable shadow in the sky map of cosmic rays detected by the ARGO-YBJ experiment in Tibet. Because the cosmic-ray particles are positively charged, the magnetic field between the Sun and the Earth deflects them from straight trajectories and results in a shift of the shadow from the true location of the Sun. Here, we show that the shift measures the intensity of the field that is transported by the solar wind from the Sun to the Earth.
52249775
Medium scale anisotropy in the TeV cosmic ray flux observed by ARGO-YBJ
B. Bartoli, P. Bernardini, X. J. Bi, I. Bolognino, P. Branchini, A. Budano, A.K. Calabrese Melcarne, P. Camarri, Z. Cao, R. Cardarelli, S. Catalanotti, S. Z. Chen, T. L. Chen, P. Creti, S.W. Cui, B. Z. Dai, A. D’Amone, Danzengluobu, I. De Mitri, B. D’Ettorre Piazzoli, T. Di Girolamo, G. Di Sciascio,* C. F. Feng, Zhaoyang Feng, Zhenyong Feng, Q. B. Gou, Y.Q. Guo, H. H. He, Haibing Hu, Hongbo Hu, M. Iacovacci, R. Iuppa, H.Y. Jia, Labaciren, H. J. Li, G. Liguori, C. Liu, J. Liu, M.Y. Liu, H. Lu, X. H. Ma, G. Mancarella, S.M. Mari, G. Marsella, D. Martello, S. Mastroianni, P. Montini, C. C. Ning, M. Panareo, B. Panico, L. Perrone, P. Pistilli, F. Ruggieri, P. Salvini, R. Santonico, S. N. Sbano, P. R. Shen, X.D. Sheng, F. Shi, A. Surdo, Y. H. Tan, P. Vallania, S. Vernetto, C. Vigorito, H. Wang, C. Y. Wu, H. R. Wu, L. Xue, Y.X. Yan, Q.Y. Yang, X. C. Yang, Z. G. Yao, A. F. Yuan, M. Zha, H.M. Zhang, L. Zhang, X.Y. Zhang, Y. Zhang, Zhaxiciren, Zhaxisangzhu, X.X. Zhou, F. R. Zhu, Q.Q. Zhu, and G. Zizzi