Status of R&D on a TPC/HBD for PHENIX Craig Woody BNL DC Upgrades Meeting December 12, 2001

C.Woody, DC Upgrades Meeting,12/14/012

3 Tracking in the Central Region in PHENIX Field Integral Momentum resolution in TPC 300 mm single point resolution in x,y,z (Simulation by N. Smirnoff) dp T /p T =0.02 PHENIX ± Field Configuration Z (m)

C.Woody, DC Upgrades Meeting,12/14/014 R&D Topics Study the electronic and optical properties of gases (CF 4, CH 4, …) Detector design (field cage, readout plane, construct prototype) Investigate readout detector options (GEM, mMega, MWPC w/pads) Design of integrated readout electronics Monte Carlo simulation studies

C.Woody, DC Upgrades Meeting,12/14/015 Initial Measurements with a Micromegas at BNL November 2001 I. Giomataris, CEA-Saclay, France G.C.Smith, B. Yu, BNL

C.Woody, DC Upgrades Meeting,12/14/016 Experimental set-up I.Giomataris,G.Smith,B.Yu

C.Woody, DC Upgrades Meeting,12/14/017 Micro-photograph of Micromegas 50  m tall Kapton pillar 50  m 5  m copper, 25  m diameter holes, 50  m pitch Pillar spacing normally 1mm ( 2mm on test sample) I.Giomataris,G.Smith,B.Yu

C.Woody, DC Upgrades Meeting,12/14/018 Anode plane: Al strips with pitch 0.95 mm Center 12 strips bussed together, to preamplifier. Load  150 pF. Rest of strips grounded for present measurements. 152 mm Active area of micromegas mesh Section used for measurements (12 mm wide by 70mm) I.Giomataris,G.Smith,B.Yu

C.Woody, DC Upgrades Meeting,12/14/019 Measurement instrumentation Collimator (25  m, 100  m, 1 mm) Monochromator Energized X-ray source Detector I.Giomataris,G.Smith,B.Yu

C.Woody, DC Upgrades Meeting,12/14/0110 Charge and Gain vs HT I.Giomataris,G.Smith,B.Yu

C.Woody, DC Upgrades Meeting,12/14/0111 +ve ion transmission I.Giomataris,G.Smith,B.Yu

C.Woody, DC Upgrades Meeting,12/14/0112 Anode Pulse Height Distribution – Ar / 20% CO 2 Linear Scale Energy Resolution = 16% FWHM (Equivalent to 15.3% for 55 Fe) Logarithmic Scale Highest amplitude peak? Collimated Cr K , 5.4 keV Gain  1000 I.Giomataris,G.Smith,B.Yu

C.Woody, DC Upgrades Meeting,12/14/0113 Anode Pulse Height Distribution – CF 4 Collimated Cr K , 5.4 keV Gain  300 (V micromegas = 570 ) Linear Scale Energy Resolution = 27% FWHM (Equivalent to 26% for 55 Fe) I.Giomataris,G.Smith,B.Yu

C.Woody, DC Upgrades Meeting,12/14/0114 Comments Micromegas mesh tested in Ar/20%CO 2 and pure CF 4 Gas gain ~ 7,000 achieved in Ar/20%CO 2 and ~ 300 in CF 4 2mm post spacing may limit upper voltage, and hence gain, with CF 4 Resn of 16% and 27% FWHM in Ar/20%CO 2 and pure CF 4 at 5.4 keV Positive ion feedthrough ~ 1% with E D = 200 V cm -1 Collimated beam  cyclic gain change (~ 3%) across mesh holes Tests continue: Ar/10%CH 4, Ar/20%DME, ~ 10ns shaping, ion drift velocity, local gain variation, lateral diffusion…. I.Giomataris,G.Smith,B.Yu

C.Woody, DC Upgrades Meeting,12/14/0115 GEM Detector Courtesy of F. Sauli (CERN) Additional GEM foils will be used to construct readout detector for TPC Drift Cell

C.Woody, DC Upgrades Meeting,12/14/0116 GEM TPC Fast signals (no ion tail)  T~20 ns : Narrow pad response function (  s ~ 1 mm): Intrinsic multi-track resolution  V ~ 1 mm 3 (Standard MWPC TPC ~ 1 cm 3 )  Improved multi-track resolution F.Sauli (CERN)

C.Woody, DC Upgrades Meeting,12/14/0117 M.Dixit (Carleton)

C.Woody, DC Upgrades Meeting,12/14/0118 Negligible effects GEM TPC Strong positive ion feedback suppression Electrons Ions With a standard Double GEM, in normal operating conditions (E DRIFT =200 V/cm), the Ion Feedback is ~ 1.5% Improve GEM geometry to reduce FB (---> ?) Gated operation easy! S. Bachmann et al, Nucl. Instr. and Meth. A 438(1999)376 F.Sauli (CERN)

C.Woody, DC Upgrades Meeting,12/14/0119 VUV Spectrometer Measures optical transmission down to 120 nm Correlate with drift measurements C.Lu & K.T. McDonald, NIM A343(1994)

C.Woody, DC Upgrades Meeting,12/14/0120 Measurements by Bob Azmoun, Stony Brook Set up to measure VUV transmission of gases Construct gas cell with MgF 2 or LiF 2 window Measure transmission of CF 4 down to ~ 1150 angstroms

C.Woody, DC Upgrades Meeting,12/14/0121 Monte Carlo Simulations Detailed TPC/HBD detector Monte Carlo already exists which is being used to optimize geometry, pad size, etc (N. Smirnoff) - study two track resolution, multihit resolution, diffusion limits, etc. - will also run GARFIELD to study field cage configurations TPC/HBD geometry is now in full PHENIX simulation package PISA (C. Aidala) Note: New proposed silicon pixel detectors have also been added to PISA; will use this together with TPC/HBD to study the effect on tracking and momentum resolution Studies are currently under way of to study electron pair signals (e.g., r,w,f, low mass pairs) in heavy ion events using EXODUS Monte Carlo (K. Ozawa) Next step will be to incorporate all three Monte Carlos programs together into PISA to do full event simulation of electron pair signals, Dalitz pairs, conversions and other background sources, combined with studies of tracking and momentum resolution, using the full PHENIX detector simulation package.

C.Woody, DC Upgrades Meeting,12/14/0122 Using the TPC to measure Low Mass Lepton Pairs and Vector Mesons in PHENIX e+e+ e-e- TPC e-e- e+e+ p p p V0V0 measured in outer PHENIX detectors (P e > 200 MeV/c) Operate PHENIX with low inner B field to optimize measurement of low momentum tracks Identify signal electrons ( r,w,f, …) and background electrons with p>200 MeV in outer PHENIX detectors Identify low momentum electrons (p<200 MeV) using dE/dx from TPC and/or Cherenkov light in HBD Calculate effective mass between all opposite sign tracks identified as electrons ( e electron > 0.9, p rej > 1:200) Reject pair if mass < 140 MeV Must provide sufficient Dalitz rejection (>90%) while preserving the true signal

C.Woody, DC Upgrades Meeting,12/14/0123 Signal survival probability Signal survival rates for several kind of Dalitz rejection ratio were calculated. Dalitz rejection ratio were calculated as a fraction of Dalitz rejected events on the invariant mass histogram. It was depends on mass cut parameter. Calculations were done for Dalitz rejection ratio of 50%, 60%, 70%, 80%, 90%, 95%, and 100%. K.Ozawa (U.Tokyo)

C.Woody, DC Upgrades Meeting,12/14/0124 Results    J/  Y Survival probability of  is 70% for dN/dy = 650, when we keep 90% Dalitz rejection ratio. Results K.Ozawa (U.Tokyo)

C.Woody, DC Upgrades Meeting,12/14/0125 TPC/HBD Detector in PISA 80 cm 70 cm 20 cm C.Aidala 55 cm CsI Readout Plane

C.Woody, DC Upgrades Meeting,12/14/0126 TPC Detector with HBD Radiator CsI Readout Plane Readout Pads DR ~ 1 cm f ~ 2 mm 20 cm 55 cm 70 cm C.Aidala

C.Woody, DC Upgrades Meeting,12/14/0127 C.Aidala EXODUS Event in TPCPISA Simulation

C.Woody, DC Upgrades Meeting,12/14/0128 Electronics Development Investigate requirements for integrated TPC readout electronics Assuming pad size of ~ 1.0 x 0.2 cm and an area of 0.8 m 2 per readout plane: 80K channels => 40K channels per readout plane (25 pads/cm 2 ) Power, cooling, services are a major design consideration assume 25 mW/ch => 4.0x10 4 x.025 = 1 kW/plane (not too bad!) Data volume is high (16 Mb unsuppressed) => need to do zero suppression in FEE Even with zero suppression, data transfer rate must be high 160 Gbit/sec => 80 Gbit/side (2-8 Gbit G-links in the future ?) What will be the cost per channel ? ($40/ch?, STAR: $25/ch) Hopefully will save in cost/channel by doing highly integrated design (but then need good estimate of design costs) Readout requirements for HBD will be different than TPC May need to operate at higher gain Channel count will be lower (depending on segmentation) Electronics will be in the PHENIX acceptance => low mass Readout must function in the existing PHENIX system readout architecture Buffer size < 4.0(6.4) msec (5 event buffer) Readout speed of 40 MHz (40 words/msec) Readout time < 40 msec (DCM speed = 25kHz) High luminosity pp running probably requires a level 3 trigger

C.Woody, DC Upgrades Meeting,12/14/0129 TPC Readout Plane and Electonics Readout Pads D R ~ 1 cm f ~ 2 mm Segmentation driven largely by resolution P.O’Connor & Bo Yu (BNL)

C.Woody, DC Upgrades Meeting,12/14/0130 Possible TPC Readout Electronics Chain P.O’Connor (BNL)

C.Woody, DC Upgrades Meeting,12/14/0131 Cost and Schedule Estimate R&D (2 years) HBD Detector Design: $250K TPC Detector Design: $500K Electronic Design: $1M (5 FTEs x 2 yrs) Total: $1.75M Construction (2 years) Detector: $100K Gas System: $100 K Detector mounted electronics: $3.2M (80K Readout $40/ch) Other readout electronics: $300K Total: $3.7 M