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Micropattern Readout Development for Gas Detectors. R.Majka, N.Smirnov DoE review, WNSL, Sept. 15-16, 2003. To meet goals of “ STAR Future Physics White Paper ” need: (for p-p and A-A beams) high event statistics good event selection (trigger) with PID possibility
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Micropattern Readout Development for Gas Detectors. R.Majka, N.Smirnov DoE review, WNSL, Sept. 15-16, 2003
To meet goals of“STAR Future Physics White Paper” need: (for p-p and A-A beams) high event statistics good event selection (trigger) with PID possibility unique (beam-beam) vertex matching. This requires: RHIC upgrade up to 40 times luminosity STAR experimental upgrade to improve data rate (the speed of tracking detectors, DAQ) trigger performance particle identification Reduction of detector mass Maintenance of present capabilities R&D motivation
TPC Event pile up TPC Space Charge distortions Additional tracking, PID Detectors Trigger power improvement Increase data rate STAR tracking issues to address } - 2. m drift distance - No space available - needs “fast” detectors - DAQ, TPC, …. STAR TPCprovento be ahigh level3D tracking detector for “complicated” Au+Au events. • Today: • Careful calibration & distortion corrections (func. Luminosity, background…) • Tomorrow: • - RHIC luminosity upgrade • Increased event pile-up • larger “space charge” distortions • STAR MUST: Increase data rate and • Install new / additional tracking / PID detectors. Unacceptable!
If STAR is going to be a RHIC II Detector … 70 cm 2x55 cm A top priority in STAR : Eventual replacement of the STAR TPC with a fast, high luminosity and high resolution tracking set up. Requires development and testing: • fast, compact TPC using micropattern readout, • integrateddirect imaging Cherenkov detector used for tracking & powerful e+/e- identification • low mass, in-expensive Pad Detectors based on micropattern technology • Si-detectors This will create: new STAR tracking setup convenient both for relativistic heavy ion and p-p program. 20 cm 55 cm Pad Det. With CsI Photocathode 16 identical modules with 35 pad-rows, double (triple) GEM readout with pad size: 0.2x1. cm². Maximum drift: 40-45 cm. “Working” gas: fast, low diffusion, good UV transparency .
GEM Detector Low mass; fast; no “high” precision parts in construction and inexpensive; any shape and pad size; double, triple or more foils setup; checked and tested.
Additional tracking / calibration detectors inside and outside of TPC Pad Detectors (GEM) ideal: Required 3d- precision low mass, fast. Solves TPC space charge distortions correction problem { but, a precision ?..(“charge” value, model, fluctuations)}and more. Convenient to use same technology as additional tracking in front of EEMC (1<|η|<2) Improve track finding and momentum resolution for high Pt ( ~40 GeV/c) particles. Together with other “fast” detectors solves the “Event pile-up” problem. Near Term STAR Tracking Improvements
Additional tracking/calibration detectors Current TPC Rinner=50cm,Router = 180cm New GEM Detectors at R=36cm & R=200cm GEM Detectors behind TPC GEM Detectors inside of TPC Crystal EMC with tracking End View Side View Tracking detector in front of EEMC
Installed R&D Laboratory at BNL (with very low funding so far) joint activity ( Yale, BNL Instr. Division, PHENIX, LEGS.) Accomplishments: “working” gas (including UV transparency & scintillation properties) GEM pad structure ( TPC and Pad Detector) GEM mass prod. & dedicated Test Lab. (at Yale ?) UV photo-converters FEE, DAQ, …. (first prototype) full scale prototypes (E-field simulation, construction approaches ) simulation / reconstruction software STAR Detector R&D
Test Drift Cell C. Thorn Joint R&D with LEGS and PHENIX Drift Stack E-Field calculation • It is used to study • Drift velocities • Drift lengths • Diffusion parameters • Energy loss (dE/dx) • Study impurities • Readout structures • Field cage design R/A sources, Laser beams, Cosmic
Absolute Quantum Efficiency of CsI photocathodes Comparison of our CsI photocathodes with a calibrated CsI PMT VUV Spectrometer CsI PMT Stack with Au coated GEM foil for depositing CsI photocathode Good quality CsI photocathodes are now being made at Stony Brook
STAR Detector R&D Plan - Next 2-3 Years • Build andtestminiTPC & Cherenkov Detector prototypes • Locate and build a GEM foil testing & calibration facility • (at Yale?) (for many future applications and experiments). • Completedesign of a TPC readout electronics • ( “first prototype”; IC or …? ) • Start engineering design of TPC/Cherenkov Detector system • Continue software activity: • - E-field quality, field cage variants, distortions, ExB, “space charge”, mechanical stability, … • - Detector response simulation. • - New STAR set up(s) performance study for different Physics • goals
TPC Prototype - Starting Next Year • Full size module • Tests field cage design • Tests materials to be used in an actual construction • Allows testing with cosmic rays • Provides structure to design & study readout plane on • Provides excellent test bench for read-out electronics Autocad geometry 3d MAXWELL Not so easy…. Also try 2D calculation using GARFIELD