Status of BESIII Weidong Li IHEP, CAS, Beijing Nanchang 17th April, 2010

17/04/2010Weidong Li2 RF SR IP Beam energy: GeV Luminosity: 3~10×10 32 cm -2 s -1 Optimum energy: 1.89 GeV Energy spread: 5.16 ×10 -4 No. of bunches: 93 Bunch length: 1.5 cm Total current: 0.91 A SR mode: 2.5 GeV BEPCII Storage Ring

17/04/2010Weidong Li3 BESIII Detector μCounter 8- 9 layers  R  =1.4 cm~1.7 cm Time Of Flight (TOF)  T (ps)= ps Barrel ps endcap Mian Drift Chamber (MDC)  P/P ( 0 / 0 ) = % (1 GeV ）  dE/dx ( 0 / 0 ) = 6-8% EMC ：  E/√E( 0 / 0 ) = % (1 GeV)  z,  (cm) = 0.5cm-0.7 cm/√E Super-conducting magnet 1.0 tesla

17/04/2010Weidong Li4 BEPCII/BESIII Commissioning milestones Oct , 2007: accumulation of electron/positron beams Nov. 18, 2007: first e+e- collision without BESIII detector Mar. 2008: Collision at 500 mA × 500 mA, Lumi.: 1 ×10 32 cm -2 s -1 Mar. 2008: first full cosmic-ray event in BESIII April 30, 2008: Move the BESIII to IP July 18, 2008: First e+e- collision event in BESIII Nov. 2008: Lumi. ~1.2  cm -2 s -1, BESIII ~ 10M  (2S) events April 14, 2009 BESIII ~100M  (2S) events (~40 days) May 14, 2009 BEPCII Lumi. ~ 3  cm -2 s -1 July 28 th, 2009 BESIII ~200M J/ Ψevents (41 days)

17/04/2010Weidong Li5 First Hadronic Event

17/04/2010Weidong Li6 Main Drift Chamber (MDC)  43 ( ) sense wire layers group to 11 superlayer  Cell is nearly square in shape  cos  from to 0.93  He + C3H8 (60%+40%) Interaction point Cosθ=0.83 Cosθ=0.93

17/04/2010Weidong Li7 MDC Calibration  T0 (Time offset) calibration: T0 is determined cell by cell using the difference between measurement drift distance and doca (distance of closest approach)  Calibration of Time-to-distance relation (X-T relation) Use Bhabha events to do initial calibration Use pion sample to calibrate X-T functions with large entrance angle  Calibration of Q-T function: to calibrate the correlation between timing difference and pulse height of the signal X-T functions of different entrance angle in layer 40 Q-T function (layer 29)

17/04/2010Weidong Li8   = 135  m    For Bhabha from  2s) data, spatial resolution is 136  m and  P is 14.7MeV/c   For Bhabha from J/  data, spatial resolution is 135  m and  P is 11.3MeV/c   For Bhabha from  data, spatial resolution is 138  m and  P is 15.7MeV/c Performance from Bhabha events

17/04/2010Weidong Li9 Run Peak value of Bhabha momentum distribution (GeV/c) Spatial resolution (  m) Calibration Monitoring J/  scan

17/04/2010Weidong Li10 MDC M.C. Tuning (1)

17/04/2010Weidong Li11 MDC M.C. Tuning (2)

e μπ p dEdx Measurement raw ADC 6% e/π K/π p/π p/K 3σ separation resolution for minimum ionization particles separation power as a function of momentum ADC comparison between MC and data MC and data dE/dx energy loss curve y≡βγ=p/m

17/04/2010Weidong Li13 Time of Flight The Geometry of TOF  Measure the time of flight charged particles  Solid coverage Barrel 0~0.83 End-cap 0.85~0.95  Barrel: 2*88 BC408, 2.4 m long, 5cm thick  Endcap ： 2* 48 BC 408  PMT: Hamamatzu R5942

17/04/2010Weidong Li14 Time Resolution and Efficiency (1) Barrel Single End Barrel Single Layer Barrel Double Layer 141ps98ps79ps Time Resolution versus TOF Counter Number Barrel Efficiency vs TOF Counter Number

17/04/2010Weidong Li15 Endcap 98ps Time Resolution versus TOF Counter Number Endcap Efficiency vs TOF Counter Number Time Resolution and Efficiency (2)

17/04/2010Weidong Li16 Kaon and Pion Separation Capability Barrel Designed Target Barrel Data  (0) = 105ps  (0) = 2  (C.L. 95.5%) separation corresponds to ΔT>3.38  ; The momentum of 2  K/  separation achieved 0.96GeV/c for barrel double layers TOF

17/04/2010Weidong Li17 Time resolution and rec. efficiency Barrel bhabhaBarrel pion Endcap bhabha

17/04/2010Weidong Li18 TOF Q distribution Bhabha Sample Dimu Sample Barrel Endcap

17/04/2010Weidong Li19 EMC Detector  Crystal CsI(Tl) Front face: ~5×5 cm 2 Rear face: ~6.5×6.5 cm 2 Length: 28 cm  Geometry 1 barrel + 2 endcaps Acceptance: 93%Х4π Total crystals: 6240 Barrel: 44 rings, 120 crystals each ring, No of crystals= 44*120=5280 Endcap: 6 rings in each endcap, No of crystals= 480*2=960

17/04/2010Weidong Li20 Energy Resolution in EMC at 1.843GeV 2Gamma : 2.7% Bhabha: 2.4%

17/04/2010Weidong Li21 φ, use digamma – – Δφ = r  (|φ 1 -φ 2 |-π ), r=distance from EMC shower to z-axis, photon position resolution is  Δ  /  2. θ, use bhabha with 0.8<e/kalp<1.0 – – Δx=l  (θ emc -θ ext ), l=distance from EMC shower to IP – – The error of MDC tracking and track extrapolation is included. Position resolution (boss6.5.1) Position correction was not done at Endcap 3.686GeV Bhabha θ 向位置分辨随 θ 的变化 Φ 向位置分辨随 θ 的变化 3.686GeV digamma 1.843GeV 位置分辨 (boss651) BarrelEast Endcap West Endcap  MC4.6mm5.6mm Data4.5mm6.0mm5.9mm  MC4.7mm6.8mm Data5.1mm7.6mm7.2mm

17/04/2010Weidong Li22 Muon Counter  One barrel (9 layers), two endcaps (8 layers each)  Coverage of the solid angle 0.9(4π)  9152 electronics channels  One dimensional readout

17/04/2010Weidong Li23 MUC Performance  Operating parameters: HV 7.2±0.2kV, threshold 100mV, gas Ar/F134a/ios-butane=50/42/8  Performance was checked with Dimu events: σ rφ ＝ mm σ z ＝ mm Data/MC comparison

17/04/2010Weidong Li24 BESIII Performance 子探测器设计指标测量值 主漂移室 动量分辨（ 1 GeV ） %0.58 % dE/dx 分辨 6-8% 6.0% （ hadron ） 5.3% (Bhabha) 量能器 能量分辨（ 1 GeV ） 2.5-3%2.5 % 位置分辨 5-7 mm6.0 mm 飞行时间时间分辨 桶部 ( 单层 ) ps98 ps (Bhabha) 端部 （单层） ps98 ps (dimuon)  子探测器  R  =1.4 cm~1.7 cm < 1.7 cm

17/04/2010Weidong Li25 Computing and Software Environment  Underlying framework GAUDI (originally developed by LHCb)  Simulation GEANT4  Other external LIBs: CERNLIB, CLHEP, ROOT, AIDA, XercesC, GDML …  Database: MySQL  Computer language: C++ (BESII legacy code written in Fortran )  Operation system: SLC4/ gcc3.4.6   Ethernet core network system with 10 Gbps bandwidth for both computing and storing data   several disk pools (~500 TB) distributed over around ~40 disk servers for data caching   a mass storage system with a tape library of ~5 PB capacity for storing raw data and reconstructed data.

BESIII Software Framework Physics Const. Svc Calib. Constant Service Detector Geom. Service Simulation Calib./Rec. Analysis BESIII Offline DB Event Data Store Raw Data Cnv Rec Data Cnv Rec.Data Event Data Flow Flow Detector Data Flow Flow Execution Sequence Sequence Navigation Svc Magnet Field Svc Particle Prop. Svc DST Data DST Data Cnv

17/04/2010Weidong Li27 BESIII Software Infrastructure  More than 250 BESIII packages, size of source code is ~180 MB  External libraries 2.7 GB  Package version management: CVS  Configuration management: CMT  Automatic software validation  Installation tool: Pacman

17/04/2010Weidong Li28 Data Management  Processing history of data files —— keep the related jobs’ information in the database together with the data files’ information Files: file location, file type, file size, event type, generated date, generated by which job, events number and file qualities. Jobs: the software version, submitted date, the location of its job options and logs.  Other interesting information: Data format vs package version Run information: trigger/event filter criteria, beam condition…… Calibration constants, dead channels/detection efficiencies….

17/04/2010Weidong Li29 Data Production  Data reconstruction Data ψ’ data （ run8093-run9025 ） Data taken at 3.65GeV (run ) J/ψ data (run9947-run10878) Time needed (1000 cores used) 3 days for all ψ’ data 1 days for 3.65 GeV 4 days for all J/ ψ’ data Data size RAW: 60TB REC: 133TB DST: 14TB  MC data production 300M psip inclusive MC 400M jpsi inclusive MC

17/04/2010Weidong Li30 Summary  The BESIII detector reached very good performance  Offline software works well MC tuning is in progress Low Pt tracking needs to be improved  We are expecting new physics results.

17/04/2010Weidong Li31