Based on real data, a new parameterized model of the main drift chamber response is proposed. In this model, we tune the ratio of good hits and the residual distribution separately. By data quality checking, the diference between simulation and data in track reconstruction efciency reduces from 1% to 0.5% averagely for the pion in J/ψ→π＋π π0, and the momentum resolution agreement improves significantly for the proton in J/ψ→ppˉ.
Data sets were collected with the BESⅢ detector at the BEPCⅡ collider at the center-of-mass energy of √s=3.650 GeV during May 2009 and at √s=3.773 GeV from January 2010 to May 2011. By analyzing the large angle Bhabha scattering events, the integrated luminosities of the two data sets are measured to be （44.49±0.02±0.44） pb-1 and （2916.94±0.18±29.17） pb-1, respectively, where the first error is statistical and the second error is systematic.
A pattern matching based tracking algorithm, named MdcPatRec, is used for the reconstruction of charged tracks in the drift chamber of the BESIII detector. This paper addresses the shortage of segment finding in the MdcPatRec algorithm. An extended segment construction scheme and the corresponding pattern dictionary are presented. Evaluation with Monte-Carlo and experimental data show that the new method can achieve higher efficiency for low transverse momentum tracks.
The number of J/ψ events collected with the BES detector at the BEPC from June 12 to July 28, 2009 is determined to be （225.3 ± 2.8） × 10^ 6 using J/ψ→inclusive events, where the uncertainty is the systematic error and the statistical one is negligible.
麦迪娜M. N. AchasovD. J. Ambrose安芬芬安琪安正华白景芝班勇J. BeckerN. BergerM. Bertani边渐鸣E. BogerO. BondarenkoI. BoykoR. A. BriereV. Bytev蔡啸A. Calcaterra曹国富常劲帆G. Chelkov陈刚陈和生陈江川陈玛丽陈申见陈晔陈元柏程和平初元萍D. Cronin-Hennessy代洪亮代建平D. Dedovich邓子艳A. DenigI. DenysenkoM. Destefanis丁伟民丁勇董燎原董明义杜书先方建房双世L. FavaF. Feldbauer封常青R. B. Ferroli傅成栋傅金林高原宁耿聪K. Goetzen龚文煊W. GradlM. Greco顾旻皓顾运厅管颖慧郭爱强郭立波郭玉萍韩艳良郝喜庆F. A. Harris何康林何苗何振亚T. Held衡月昆侯治龙胡海明胡继峰胡涛黄彬黄光明黄金书黄性涛黄燕萍T. Hussain姬长胜纪全季晓斌季筱璐贾卢魁姜丽丽江晓山焦健斌焦铮金大鹏金山景繁凡N. Kalantar-NayestanakiM. KavatsyukW. Kuehn赖蔚J. S. Lange潘振声李春花李澄李翠李德民李飞李刚李海波李家才李康李蕾李宁博李秋菊李绍莉李卫东李卫国李晓玲李小男李学潜李秀荣李志兵梁昊梁勇飞梁羽铁廖广瑞廖小涛刘北江C. L. Liu刘春秀刘春燕刘福虎刘芳刘峰刘虎刘宏邦刘汇慧刘怀民刘红薇刘觉平刘魁勇刘凯刘坤刘佩莲刘树彬刘翔刘晓海刘勇刘豫斌刘振安刘志强刘智青H. Loehner鲁公儒吕海江吕军光
The numbers of ψ（3686） events accumulated by the BESⅢ detector for the data taken during 2009 and 2012 are determined to be（107.0±0.8）×10^6 and（341.1±2.1）×10^6, respectively, by counting inclusive hadronic events,where the uncertainties are systematic and the statistical uncertainties are negligible. The number of events for the sample taken in 2009 is consistent with that of the previous measurement. The total number of ψ（3686） events for the two data taking periods is（448.1±2.9）×10^6.
Data quality monitoring （DQM） plays an important role in data taking at the BESⅢ experiments.DQM is used to monitor detector status and data quality.A DQM framework （DQMF） has been developed to make it possible to reuse the BESⅢ offline reconstruction system in the online environment.In this framework,the DQMF can also simulate a virtual data taking environment,transfer events to the event display,publish histograms to a histogram presenter in a fixed interval,and dump histograms into a ROOT file.The DQMF has been stably running throughout BESⅢ data taking.
We developed a least squares fitter used for extracting expected physics parameters from the correlated experimental data in high energy physics. This fitter considers the correlations among the observables and handles the nonlinearity using linearization during the X2 minimization. This method can naturally be extended to the analysis with external inputs. By incorporating with Lagrange multipliers, the fitter includes constraints among the measured observables and the parameters of interest. We applied this fitter to the study of the D^-D~ mixing parameters as the test-bed based on MC simulation. The test results show that the fitter gives unbiased estimators with correct uncertainties and the approach is credible.
A method to estimate the efficiency of event start time determination at BESIII is developed. This method estimates the efficiency at the event level by combining the efficiencies of various tracks （e, μ, π, K, p, y） in a Bayesian way. Efficiencies results and the difference between data and MC at the track level are presented in this paper. For a given physics channel, event start time efficiency and systematic error can be estimated following this method.
Using data samples collected at center-of-mass energies of √s=4.009, 4.230, 4.260, and 4.360 GeV with the BES0 detector operating at the BEPC/ collider, we perform a search for the process e＋e-→γχc,j （J =0, 1, 2） and find evidence for e＋e-→γχc1 and e＋e-→γχc2 with statistical significances of 3.0σ and 3.4σ, respectively. The Born cross sections σB（e＋e-→γχc,j）, as well as their upper limits at the 90% con dence level （C.L.） are determined at each center-of-mass energy.
