January 7th, USTC, Hefei 1 A CGEM Prototype for BESIII Inner Drift Chamber Upgrade R. Baldini Ferroli, (INFN-LNF) for a China-Italy Collaboration Project Co-financed by the Italian Ministry for Foreign Affairs (MAE) January 7th, USTC, Hefei 2 Outline BESIII requirements for a CGEM Inner Tracker Prototype targets LNF CGEM miniworkshop Assembling a KLOE2 CGEM GASTONE32 analog readout Possible improvements January 7th, USTC, Hefei 3 QUN OUYAN at the CGEM workshop January 7th, USTC, Hefei 4 GEM: principle of operation By applying V between the two copper sides, an electric field as high as ~100 kV/cm is produced into the holes which act as multiplication channels for electrons produced in the gas by a ionizing particle. Gains up to 1000 can be easily reached with a single GEM foil. Higher gains (and/or safer working conditions) are usually obtained by cascading two or three GEM foils. A Triple-GEM detector is built by inserting three GEM foils between two planar electrodes, which act as the cathode and the anode. LHCb geom The GEM (Gas Electron Multiplier) [F.Sauli, NIM A386 (1997) 531] is a thin (50 m) metal coated by a kapton foil perforated by a high density of holes (70 m diameter, pitch of 140 m) standard photo-lithographic technology. January 7th, USTC, Hefei GEM detector features flexible geometry arbitrary shape: rectangular, cylindrical ultra-light structure very low material budget: 50 MHz/cm2 high safe gains: > 10 4 high reliability: low discharge, P d < per incoming particle rad hard: up to 2.2 C/cm 2 integrated over the whole active area without permanent damages (corresponding to 10 years of operation at LHCb1) high spatial resolution: down to 60m ( COMPASS with analog readout Nucl.Phys.Proc.Suppl. 125 (2003) ) good time resolution: down to 3 ns (with CF 4 ) 5 January 7th, USTC, Hefei 6 6 m 7m7m Lead/scintillating fiber 98% coverage of solid angle 88 modules (barrel + end-caps) 4880 PMTs (two side read-out) Lead/scintillating fiber 98% coverage of solid angle 88 modules (barrel + end-caps) 4880 PMTs (two side read-out) 4 m diameter 3.3 m length 90% helium, 10% isobutane 12582/52140 sense/tot wires All-stereo geometry 4 m diameter 3.3 m length 90% helium, 10% isobutane 12582/52140 sense/tot wires All-stereo geometry Electromagnetic Calorimeter Drift Chamber r = 150 m z = 2 mm V = 3 mm p /p = 0.4 % r = 150 m z = 2 mm V = 3 mm p /p = 0.4 % E /E =5.4%/ t = 54 ps/ E /E =5.4%/ t = 54 ps/ 100 ps(calib) 100 ps(calib) B = 0.52 T KS = 0.6 cm KL = 340 cm K = 95 cm January 7th, USTC, Hefei 7 To improve vertex reconstruction of K s, and and K s - K L interference measurements: 1. r 200 m and z 350m 2. low material budget: < 2% X 0 K S vertex resolution will improve of about a factor 3 from present 6mm 4 CGEM layers :from IP to DC Inner wall 700 mm active length XV strips-pads readout (~40 o stereo angle) no molds, no glue A new proposal (Rui de Oliveira and G. Bencivenni) January 7th, USTC, Hefei Summary CGEM could be a solution for a new Inner Tracker A relevant gain is achieved in the longitudinal view Transverse momentum resolution worsening (?) at low momenta only A prototype with analog readout in two years, if: more people join this project January 7th, USTC, Hefei 41 Thank you for your attention