13338492
DAQ Architecture Design of Daya Bay Reactor Neutrino Experiment
The Daya Bay Reactor Neutrino Experiment consists of seventeen detectors distributed in three underground experimental halls. Each detector has a separate VME readout crate that contains the trigger and electronics modules. The data acquisition (DAQ) system reads data fragments from electronics and trigger modules and concatenates them into an event in each crate. The DAQ monitors the data quality, merges the event streams from each hall, and records these data to disk. The DAQ architecture is designed as a multi-level system based on the BESIII DAQ and ATLAS TDAQ systems using embedded Linux, VME bus system, advanced commercial computers and distributed network technologies. This paper presents the main DAQ design requirements, and the hardware and software architectures.
12149444
Observation of a Near-Threshold Enhancement in the p-anti-p Mass Spectrum from Radiative J/psi --> gamma-p-anti-p Decays
We observe a narrow enhancement near 2m{sub p} in the invariant mass spectrum of p{bar p} pairs from radiative J/{psi} {yields} {gamma}p{bar p} decays. No similar structure is seen in J/{psi} {yields} {pi}{sup 0} p{bar p} decays. The results are based on an analysis of a 58 million event sample of J/{psi} decays accumulated with the BESII detector at the Beijing electron-positron collider. The enhancement can be fit with either an S- or P-wave Breit Wigner resonance function. In the case of the S-wave fit, the peak mass is below 2m{sup p} at M = 1859{sub -10}{sup +3} (stat){sub -25}{sup +5} (sys) MeV/c{sup 2} and the total width is {Lambda} < 30 MeV/c{sup 2} at the 90 percent confidence level. These mass and width values are not consistent with the properties of any known particle.
7127495
Precision measurement of the mass of the tau lepton
An energy scan near the tau pair production threshold has been performed using the BESIII detector. About 24 pb(-1) of data, distributed over four scan points, were collected. This analysis is based on t pair decays to ee, e mu, eh, h, hh, e.,. and p. final states, where h denotes a charged p or K. The mass of the t lepton is measured from a maximum likelihood fit to the t pair production cross- section data to be m(tau) = 1776.91 +/- 0.12_0.10 - 0.13 _ MeV/c(2), which is currently the most precise value in a single measurement.
123325671
BESIII track fitting algorithm
A track fitting algorithm based on the Kalman filter method has been developed for BESⅢ of BEPCⅡ. The effects of multiple scattering and energy loss when the charged particles go through the detector, non-uniformity of magnetic field (NUMF) and wire sag, etc., have been carefully handled. This algor...
116994417
Measurement of $\eta^\prime\rightarrow \pi^+\pi^- e^+e^-$ and $\eta^\prime\rightarrow \pi^+\pi^-\mu^+\mu^-$
Based on a sample of 225.3 million J/\psi events accumulated with the BESIII detector at the BEPCII, the decays of \eta' to pi+pi-l+l- are studied via J/\psi to \gamma\eta'. A clear \eta' signal is observed in the pi+pi-e+e- mass spectrum, and the branching fraction is measured to be \BR(\eta' to pi+pi-e+e-) = (2.11\pm0.12 (stat.)\pm0.15 (syst.))\times10^{-3}, which is in good agreement with theoretical predictions and the previous measurement, but is determined with much higher precision. No \eta' signal is found in the pi+ pi- mu+ mu- mass spectrum, and the upper limit is determined to be \BR(\eta' to pi+ pi- mu+ mu-)<2.9\times10^{-5} at the 90% confidence level.
36972437
The architecture of BESIII offline database
This paper presents the BESIII Offline Database for use in the current BESIII experiment at IHEP. The database can be used for the purpose of offline and physical analysis. It manages the history status data of detectors, electronics, slow control subsystem, and online subsystem. These are the data necessary for the online DQM monitor, reconstruction, calibration and data analysis. BESIII offline database also be used to manage calibration data, DQM data and Monte Carlo data. These are also the data necessary for the data analysis. The BESIII database also provide user with web services to make it possible to monitor the status of detectors, slow control subsystem, and online subsystem locally or remotely. The database engine is MySQL server. The database technology route and the database services for the distributed application environment are also presented in this paper.
120311240
Observation of $J/\psi \rightarrow p\bar{p}a_{0}(980)$ at BESIII
Using $2.25\times10^{8}$ $J/\psi$ events collected with the BESIII detector at the BEPCII storage rings, we observe for the first time the process $J/\psi\rightarrow p\bar{p}a_{0}(980)$, $a_{0}(980)\rightarrow \pi^{0}\eta$ with a significance of $6.5\sigma$ ($3.2\sigma$ including systematic uncertainties). The product branching fraction of $J/\psi\rightarrow p\bar{p}a_{0}(980)\rightarrow p\bar{p}\pi^{0}\eta$ is measured to be $(6.8\pm1.2\pm1.3)\times 10^{-5}$, where the first error is statistical and the second is systematic. This measurement provides information on the $a_{0}$ production near threshold coupling to $p\bar{p}$ and improves the understanding of the dynamics of $J/\psi$ decays to four body processes.
119262603
Charmonium and Light Meson Spectroscopy
This talk reviews recent experimental results on selected topics in the spectroscopy of charmonia, charmonium-like states and light mesons.
118967353
Exotic in Leptonic Machines
Selected topics of exotics in leptonic machines are presented, including recent discovery of abnormal structures around the ppbar threshold and new information of the XYZ (charmonium-like) states.