1 / 34

A Fast, Compact TPC for Dalitz Rejection and Inner Tracking in PHENIX

A Fast, Compact TPC for Dalitz Rejection and Inner Tracking in PHENIX. Craig Woody BNL. RHIC Detector Advisory Committee Review December 19, 2002. Outline. Physics goals Description of the combined TPC/HBD detector Main R&D Issues Goals, milestones, funding.

elda
Download Presentation

A Fast, Compact TPC for Dalitz Rejection and Inner Tracking in PHENIX

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. A Fast, Compact TPC for Dalitz Rejection and Inner Tracking in PHENIX Craig Woody BNL RHIC Detector Advisory Committee Review December 19, 2002

  2. Outline • Physics goals • Description of the combined TPC/HBD detector • Main R&D Issues • Goals, milestones, funding C.Woody RHIC Detector Advisory Committee Review 12/19/02

  3. Physics measurements addressed by this detector • Low mass lepton pairs and vector mesons • Charm and B physics with resolved secondary verticies • - low mass tracking just outside vertex detector • - allows measurement in both heavy ion and pp running • Improved inner tracking for PHENIX • - increased h and f coverage • (needed for jet and g-jet physics) • - tracking through the magnetic field • (improves momentum resolution, the ability to measure • real low pT tracks, and to reject high pT background tracks) C.Woody RHIC Detector Advisory Committee Review 12/19/02

  4. e- p e+ p V0 e- TPC / HBD p measured in outer PHENIX detectors (Pe> 200 MeV/c) e+ Strategy for Low Mass Pair Measurement • Operate PHENIX with low inner B field • to optimize measurement of low • momentum tracks • Identify signal electrons (low mass pairs, • r,w,f, …) with p>200 MeV in outer • PHENIX detectors • Identify low momentum electrons • (p<200 MeV) using Cherenkov light from • HBD and/or dE/dx from TPC • Calculate effective mass between all • opposite sign tracks identified as electrons • (eelectron> 0.9, prej> 1:200) • Reject pair if mass < 130 MeV Must provide sufficient Dalitz rejection (>90%) while preserving the true signal C.Woody RHIC Detector Advisory Committee Review 12/19/02

  5. Dalitz Rejection and Vector Meson Survival Probability Survival probability ofr,w,f is ~85% for Dalitz rejection ratio of 90%. Central Au+Au collisions ee = 100%, prej = 1:200 (HBD,RICH) K. Ozawa C.Woody RHIC Detector Advisory Committee Review 12/19/02

  6. decays a conversions DC B PHENIX Tracking PHENIX presently has no tracking inside magnetic field Drift Chamber Momentum determined by measuring a angle PT distribution of charged tracks - DC only - PC1-PC3 matching - Random background Tracking through the magnetic field will help eliminate backgrounds from decays and conversion which are problematic at high PT C.Woody RHIC Detector Advisory Committee Review 12/19/02

  7. Field Integrals PHENIX Inner Magnetic Field ±Configuration Inner field itself is non-uniform BR z=20cm BZ Inner Coil creates a “field free” (∫Bdl=0) region inside the Central Magnet Tracking with TPC will aid in electron id in HBD C.Woody RHIC Detector Advisory Committee Review 12/19/02

  8. Tracking at High Field and Vertex Resolution ++ Configuration B = 9 KG V. Rykov Momentum resolution Impact parameter resolution C.Woody RHIC Detector Advisory Committee Review 12/19/02

  9. TPC/HBD Detector • Fast, compact TPC • R<70 cm, L< 80 cm, Tdrift4 msec • Serves as an inner tracking detector • in both HI and pp, providing tracking • through the central magnetic field • Df = 2p, |h| 1.0 • Dp/p ~ .02p • Provides electron id by dE/dx •  e/p separation below 200 MeV • HBD is a proximity focused Cherenkov • detector with a ~ 50 cm radiator length • Provides electron id with minimal signals • for charged particles •  “Hadron Blind Detector” CsI Readout Plane TPC Readout Plane Drift regions Readout Pads GEMs are used for both TPC and HBD C.Woody RHIC Detector Advisory Committee Review 12/19/02

  10. Rates and Occupancy Requirement: The TPC should work at the highest HI and pp luminosities Au-Au : L ~ 8 x 1027 cm-2s-1 L x s = 8 x 1027 x 7.2 b = 58 kHz dNch/dy = 150 (min.bias)  ~ 250 trks/evt, 15 trks/msec Nhits/evt ~ 100K  occupancy ~ 1% 100 MeV e- Innermost pad row ~ 3%occupancy C.Aidala p-p : L ~ 2 x 1032 cm-2s-1 L x s = 2 x 1032 x 60 mb (Ss = 500 GeV) = 12MHz  ~ 50 events in 4 msec drift time dNch/dy = 2.6  ~ 5 trks/evt, 52 trks/msec 35 pad rows, 80K channels DR ~ 1 cm, RDf ~ 2 mm DZ ~ 2.5 mm (140 samples) 11M voxels C.Woody RHIC Detector Advisory Committee Review 12/19/02

  11. R & D Issues for the TPC • Performance of GEM detectors • Stability, gain uniformity, aging • Studiesof fast drift gases (CF4, CH4, mixtures…) • - Drift velocities, drift lengths, diffusion parameters, dE/dx, ion feedback,… • - Optical transmission into the VUV for use with HBD • Optimize spatial resolution • Detector component design • Readout plane • Field cage • Understand E x B effects for drifting charge in non-uniform magnetic field • Understand space charge effects (do we need gating ?) • Electronics • Infrastructure issues • Requires engineering and integration study (additional manpower needed) C.Woody RHIC Detector Advisory Committee Review 12/19/02

  12. GEM Detectors at BNL Several multistage GEM detectors have been obtained from Sauli’s group at CERN and are currently being used for detector studies at BNL High precision (100 mm) scanning x-raysource B. Yu C.Woody RHIC Detector Advisory Committee Review 12/19/02

  13. miniTPC 35 pad rows CH4 p k dE/dx (keV/cm) p e 0.2 1.0 P (GeV/c) Double GEM Gas Gain Uniformity B. Yu N. Smirnov 5.4keV collimated x-rays (~1mm2) scanned with a 1mmx1mm grid over 9cmx9cm area. e/p separation below 200 MeV Good gain uniformity and energy resolution is important for particle id using dE/dx Relative Amplitude C.Woody RHIC Detector Advisory Committee Review 12/19/02

  14. GEM Spatial Resolution GEM’s produce inherently good spatial resolution due to direct collection of electron signal J.Va’vra et.al., NIM A324 (1993) 113-126 Diffusion Limit sL~ 80 mm/35cm  ~ 500 mm Must keep channel count low C.Woody RHIC Detector Advisory Committee Review 12/19/02

  15. Fine “Zigzag” pattern Interpolating Pad Readout Two Intermediate Strips Overall position error: 93µm rms Including ~ 100µm fwhm x-ray p.e. range, 100µm beam width, alignment errors Single Intermediate Zigzag B. Yu C.Woody RHIC Detector Advisory Committee Review 12/19/02

  16. Test Drift Cell C. Thorn Joint R&D with LEGS Drift Stack E-Field calculation • Will be used to study • Drift velocities • Drift lengths • Diffusion parameters • Energy loss (dE/dx) • Study impurities • Readout structures • Field cage design C.Woody RHIC Detector Advisory Committee Review 12/19/02

  17. 5 cm 200 ch readout card 15 cm TPC Readout Readout features Readout Pads 35 pad rows, 5K ch/plane DR ~ 1 cm, RDf ~ 2 mm • R&D Issues • Need to minimize power • Distribution of analog and digital signals • Low noise, zero suppression • Data volume (triggering) C.Woody RHIC Detector Advisory Committee Review 12/19/02

  18. TPC Readout Electronics • Considerations • Speed (need ~ 40 Mhz) • Power (< 100 mW/ch total) • Compatibility w/PHENIX readout • Cost and availability ADC each channel AD9289 Serial ADC 4 ch / 65MHz / 8 bit AMU/ADC C-Y. Chi • Options • Commercial ADC + FPGA • ALICE ALTRO chip • Custom ASIC • (may only need for preamp/shaper) C.Woody RHIC Detector Advisory Committee Review 12/19/02

  19. HBD Readout Electronics • Considerations • Low noise (signal ~ 40 p.e.’s) • Low mass (inside PHENIX accept.) • (signals brought to edge of detector) • ~ 5K channels - too few for ASIC • Needs time measurement ~ few ns C-Y. Chi • Options • Separate (slow) ADC + TDC • Fast ADC used to • extrapolate T0 measurement C.Woody RHIC Detector Advisory Committee Review 12/19/02

  20. FY03 R&D Goals • Complete TPC test cell • Carry out gas studies of TPC with GEM readout • Preliminary design of TPC field cage & readout plane • Carry out CsI photocathode studies with GEMs • Measure CF4 scintillation (NSLS Feb ’03) • Carry out aging studies (GEMs, CsI, CF4) • Measure HBD response to hadrons and electrons • Define HBD detector configuration • Preliminary engineering design and integration study • Preliminary design of TPC and HBD electronics • Build test setup for TPC and HBD electronic components • Improved Monte Carlo simulations C.Woody RHIC Detector Advisory Committee Review 12/19/02

  21. FY03 R&D Milestones • Demonstrate proof of principle of TPC with GEM readout • Demonstrate proof of principle of CsI + GEM operation • Determine feasibility of operation in pure CF4(or choose alternative gas) • Demonstrate feasibility of combined TPC/HBD detector concept • Decide on ALICE ALTRO chip, commercial ADC+FPGA or ASIC for TPC • Decide on slow ADC+ TDC or fast ADC for HBD readout C.Woody RHIC Detector Advisory Committee Review 12/19/02

  22. R&D Goals & Milestones for FY04 & FY05 • FY2004 • Construct TPC/HBD prototype detectors • Construct gas system for prototype detectors • Build prototype HBD and TPC electronics • Build test setup for TPC and HBD electronics • Carry out detailed engineering design and integration study • Carry out further detailed Monte Carlo simulations • FY2005 • Complete engineering and integration design • Complete TPC detector design • Complete design of TPC readout electronics C.Woody RHIC Detector Advisory Committee Review 12/19/02

  23. R&D Budget Request Additional institutional manpower contributions • Related R&D Efforts • Joint effort with STAR • (includes additional • equipment costs) • LEGS TPC • Detector R&D at FIT* • TPC w/GEM readout • for NLC/TESLA *Florida Institute of Technology - 2 physicists, 1 student interested C.Woody RHIC Detector Advisory Committee Review 12/19/02

  24. Additional Slides C.Woody RHIC Detector Advisory Committee Review 12/19/02

  25. CsI Photocathode 20 cm 55 cm 70 cm GEANT Simulation of TPC/HBD Single 100 MeV/c electron track C.Aidala TPC/HBD detector in PHENIX PISA simulation package C.Woody RHIC Detector Advisory Committee Review 12/19/02

  26. Fast drift gases - CH4 and CF4 40 cm drift ~ 3-4ms Requires high drift field 10 cm /ms 12 cm /ms CH4 CF4 -Ar C2 H6 CF4 P10 C2 H2 1 V / cm / Torr 1 KV / cm C.Woody RHIC Detector Advisory Committee Review 12/19/02

  27. Ions Electrons Ion Feedback in GEMs F.Sauli Triple GEM B.Yu C.Woody RHIC Detector Advisory Committee Review 12/19/02

  28. Space Charge Distortions Distortion field components in TPC volume. Emax ~ 1.4V/cm Emax ~ 1.7V/cm Radial Axial B. Yu 200 GeV Au+Au Ion feedback 10% G ~ 103 r ~ 10-8 C/m3 q ~ 2.5 x 10-3 rad Dx ~ 0.5 mm for 40 cm drift C.Woody RHIC Detector Advisory Committee Review 12/19/02

  29. GEM Aging and Discharge Rates • Experience from COMPASS • Triple GEM greatly reduces discharge • probability rate • no discharges over months of operation • no loss of gain or resolution due to aging S.Bachmann et.al., NIM A479 (2002) 294 Triple GEM • Aging rate at RHIC • Min bias  1.3 x 107 trks/sec • dE/dx = 80 ion pairs/cm (CH4) • Gain = 2 x 103 • dQ/dt = 64 C/yr, A= 8247 cm2 • dQ/dA = 0.08 mC/mm2/yr Triple GEM ArCO2, G~8.5x103 S.Kappler, 2001 International Workshop on Aging Phenomena in Gaseous Detectors http://www.desy.agingworkshop C.Woody RHIC Detector Advisory Committee Review 12/19/02

  30. VUV Spectrometer Used for measurements of VUV gas transmission and CsI quantum efficiency B.Azmoun C.Woody RHIC Detector Advisory Committee Review 12/19/02

  31. Commercial ADC C-Y. Chi C.Woody RHIC Detector Advisory Committee Review 12/19/02

  32. signal L2 trigger (keep the buffer) L1 trigger (write to buffer) Read or drop L2 events L1 (W) L2 (keep) L1 (W) L1 (W) L2 (keep) L1 (W) L1 (W) L2 (keep) L1 (W) L1 (W) L1 (W) L1 (W) Use of ALTRO Chip in PHENIX ALTRO’s event buffer could be divided to 8 * 512 word blocks or 4 * 1024 words blocks Backend of the ALTRO chip 15 write clocks Time Problem for PHENIX a) no overlapping event buffers (space between L1 triggers could be as short as 4 beam clocks) b) L1 trigger delay is too short (i.e., 15*25 ns = 375 ns) C-Y. Chi C.Woody RHIC Detector Advisory Committee Review 12/19/02

  33. Two overlapping TPC data block ALTRO 512 words buffers TPC data block PHENIX L1 Two PHENIX L1 Use of ALTRO Chip in PHENIX • We need to generate a fake L1 trigger every 512*25ns = 12.8 ms. ( used as L1 delay buffer) • Our L1 trigger will become ALTRO chip’s L2 trigger. • We read the L1 data buffers to a FPGA/ASIC. We will parse our data blocks from ALTRO data buffers C-Y. Chi C.Woody RHIC Detector Advisory Committee Review 12/19/02

  34. FY 2003 FY 2004 FY 2005 FY 2006 FY 2007 FY 2008 Implementation Plan HBD TPC R&D (3 years) Total: $1.4M (LDRD for $100K in FY 2001 & FY 2002) R&D R&D Construction • Construction (2 years) • Detector: $250K • Gas System: $250 K • Detector mounted electronics: $4.0M • (80K Readout Channels @ $50/ch) • Other readout electronics: $500K • Total: $5.0 M Construction Operation Operation C.Woody RHIC Detector Advisory Committee Review 12/19/02

More Related