1 / 24

FGT Layout Simulation Results

 =1.0.  =1.5.  =2.0. 1 2 3 4 5 6  FGT disks. e+ shower E T =40 GeV. FGT Layout Simulation Results. Detector requirements Optimal location *) Ability of e+/e- separation Simu GEM response Strip layout *) , occupancy e/h discrimination To-do list

sharne
Download Presentation

FGT Layout Simulation Results

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. =1.0 =1.5 =2.0 1 2 3 4 5 6  FGT disks e+ shower ET=40 GeV FGT Layout Simulation Results • Detector requirements • Optimal location *) • Ability of e+/e- separation • Simu GEM response • Strip layout *), occupancy • e/h discrimination • To-do list • Summary Jan Balewski, MIT FGT Project Review January 7-8, 2008 *) still being finalized

  2. FGT Requirements • Reconstruct charge of e+, e- from W decay for PT up to 40 GeV/c • Aid electrons / hadrons discrimination • Allow for uniform performance for z-vertex spread over [-30,+30] cm • Fit in geometrical envelope vacated by the West Forward TPC • Benefit from other ‘central’ trackers: IST, SSD • Relay on vertex reconstruction and Endcap shower-max hit • Relay on Endcap towers for energy reconstruction • Minimize amount of material on the path of tracks • Align FGT segmentation with TPC sector boundaries and Endcap halves • Assure relative alignment vs. TPC is double with real particles

  3. Optimization of FGT Disks Location in Z a) Barrel EMC Used TPC volume nHits>=5 Endcap EMC =1.0 Zvertex=0cm =1.5 =2.0 SSD IST1,2 beam  1 2 3 4 5 6  R-‘unconstrained’ FGT disks Zvertex=+30cm Zvertex=-30cm c) b) 1 2 3 4 5 6 1 2 3 4 5 6 FGT disks geometry: Rin=7.5cm, Rout=41cm, Z1…Z6=60…150cm, Z=18cm • 5 hits required for helix reco • FGT sustains tracking if TPC provides below 5 hits • use TPC, SSD,IST for • Zvertex <~0 and <~1.3 • displaced • -30< Z_vertex < +30 cm

  4. Optimization of FGT Disk Radii Rxy –  representation Endcap Used TPC volume nHits>=5 track = 1.7  =1.0 Zver=0cm =1.5 =2.0 TPC If nHit>5 Endcap SMD FGT  1 2 3 4 5 6 1 2 3 4 5 6  FGT SSD IST1,2 =1.7  ‘generous’ FGT disks geometry : Rin=7.5cm, Rout=41cm, Z1…Z6=60…150cm, Z=18cm Rxy – Z representation • Optimization Criteria • Each track must cross the vertex and Endcap EMC • 6 FGT disk are needed to provide enough hits for tracks at all  and all z-vertex • Single track crosses less than 6 FGT disks • Relay on TPC & SSD at ~1 Vertex 

  5. Revised Compact FGTevery disk plays a role Critical FGT coverage depends on Z-vertex Rin=18cm, Rout=37.6cm, Z1=70cm, …,Z6=120cm, Z=10 cm ZVERTEX=-30cm ZVERTEX= 0cm ZVERTEX=+30cm Rxy (cm)  Endcap TPC FGT Vertex track  

  6. FGT Enables Reco of Sign of e+,e- 2mm Sagitta (cm) Sagitta (cm) 2mm Endcap SMD hit =1.5mm Y/cm Good Q-sign Wrong Q-sign 100cm reco track  1  of reco track Sagitta=2mm Limit for  pT track Tracks uniform in  and pT 40cm 3 FGT hits =70m 20cm X/mm Vertex =200m 1.0 2.0 mm 0

  7. Track & Charge Sign Reco Efficiency FGT geometry: Rin=18cm, Rout=37.6cm, Z1=70cm, …,Z6=120cm, Z=10 cm • N0 – thrown electrons, ET=30 GeV • N1 – reco tracks (<3 mrad) • N2 – reco tracks w/ correct charge sign • (pT from 2D circle fit, ET constrain not used, 1 track/event) • Track reco efficiency >~80% for  up to 2.0 • Wrong charge reco <~20% only for  > 1.5

  8. Large A(W-) for >1.5, FGT Essential W- PT>20 GeV/c Charge Reco Efficiency Using: TPC+vertex+ESMD+SSD+IST+FGT *) Reasonable yield Largest A 2008 Configuration TPC+vertex+ESMD  low efficiency  *) geometry : Rin=7.5cm, Rout=41cm, Z1…Z6=60…150cm, Z=18cm

  9. Detailed Simulation of GEM Response R-axis strip 2 mm phi-axis strip 1 mm (R*) 40m • ionization and charge amplification • spatial quantization on GEM foil grid • charge collection by strip planes • 1D cluster reconstruction • Add: time dependence  pileup simu Realistic MIP charge profile collected by R- and -strips 1D Cluster finder resolution similar to Ferm-Lab test beam results

  10. FGT Strip Layout *) y Bottom R-layer pitch 800m x 326 R-strips X z 15 deg Endcap halves y Top -layer 949 -strips pitch 600m Essential for PT reco ~ 50% transparency x FGT quadrant boundaries match to Endcap segmentation  needed for 3D track recognition, resolving ambiguities Compact FGT Rin=18cm, Rout=37.6cm, Z1=70cm, …,Z6=120cm, Z=10 cm *) close to final

  11. Estimation of Strip Occupancy tracks 2 1 1 -strips 400 m pitch R-strips 45 deg long 0  1 track/strip per 1000 minB events tracks Track rate per strip for minB PYTHIA events @ s500 GeV Based on FGT geometry: Rin=15cm, Rout=41cm R=41cm R=15cm 0.8 0.4 0 =0 deg =90 • pileup from minB events dominates • 1.5 minB interactions/RHIC bXing • 300nsec response of APV •  3 bXings pile up • Total pileup of 5 minB events per trigger event • 1 track per FGT quadrant per minB event • (scaled from simu below) • Cluster size: 1mm along , 2mm along R • Cluster occupancy per triggered event per quadrant • -strips (span ~43cm)1.2% occupancy • R-strips (span 25cm)  4% occupancy • (uncertainty factor of 2) minB PYTHIA event @ s=500 GeV

  12. e/h Discrimination : PYTHIA Events Isolation & missing-PT cuts suppress hadrons by ~100 Hadrons from PYTHIA M-C QCD events e+, e- from PYTHIA M-C W-events

  13. e/h Endcap EMC  additional factor of 10 Pre Showers Shower Max Post Shower =2.0 30 GeV 0 GeV e+ =1.08 + GeV  Simu of Endcap response to Electrons (black) & charge pions (red) with ET of 30 GeV e+ + Endcap + e+ Projective tower Shower from electron E=30 GeV  ~15 GeV ET Trigger threshold

  14. Real Electrons Reconstructed in Endcapproof of principle Endcap-based cuts TPC 6<P<8 GeV/c TPC 10<P<14 GeV/c  e+, e- • MIP e+, e- • MIP Identified e+,e- in p+p 2006

  15. To-do List • completion of detailed (a.k.a. ‘slow’) simulator for GEM response • develop 3D tracking with pattern recognition, integrate w/ STAR tracking • include pileup from 3 events in reco of physics events • implement and optimize full array of e/h discrimination techniques • completion of full W event simulation and comparison to full hadronic QCD events simulation • determine background contribution from Z0 and heavy flavor processes, above pT>20 GeV/c

  16. FGT Simulation Summary • Will be able to reconstruct charge of e+, e- from W decay for PT up to 40 GeV/c with efficiency above 80% • There is enough information recorded to discriminate electrons against hadrons • Allow for uniform performance for z-vertex spread over [-30,+30] cm, OK • Will fit in geometrical space • Will use hits from IST, SSD • Will relay on vertex reconstruction and Endcap shower-max hit & energy • FGT quadrants are aligned with TPC sector boundaries and Endcap halves • FGT disks 1 & 2 overlap with TPC allowing relative calibration

  17. BACKUP

  18. Track Reco Strategy 1 2 3 4 5 6  FGT • Select EMC cluster with large energy (ET>15 GeV) • Find Endcap SMD cluster location ( x~y~5cm) • Find transverse vertex position (x~y~0.2mm) • Eliminate all FGT hits outside the cone: vertex SMD hit • Resolve remaining ambiguities (if any) by • comparing R vs.  charge 2 1 x 5 x 4 x 3

  19. TPC reco with 5 points ‘regular’ tracking 5-hits tracking ‘regular’ tracking 5-hits tracking

  20. Alternative Snow-flake Strip Layout 326 R-strips  12-fold local Cartesian ref frame Top -layer 949 -strips pitch 600m As in Proposal  Bottom R-layer pitch 800m

  21. FGT Material budget UPGR13, maxR=45 cm 0.5*Xo Z vert= - 30cm Z vert= 0cm Z vert= + 30cm Non-FGT material upfront Non-FGT material upfront Non-FGT material upfront 0 0.5*Xo 0

  22. Study of stability of efficiency • Studied variations of efficiency (shown in proposal): • degraded FGT cluster resolution (80m  120m, OK) • reduced # of FGT planes (6 4 , bad, too few hits/track) • degraded transverse vertex accuracy (200m 500m, OK) • FGT cluster finding efficiency (100%  90%, OK , details)

  23. Detailed Simulation of GEM Response (1) Latice attractors spaced 130 m Charge from this hexagon is attracted by the hole Hole in GEM foil amplifies charge cloud Primary ionization R-axis strip Pitch=800m xhit phi-axis strip pitch=600m Amplified signal is displaced best • ionization and charge amplification • spatial quantization on GEM grid • charge collection by strip planes • 1D cluster reconstruction

  24. Simulated FGT Response (2) 14 prim pairs/track 14 prim pairs/track 22 eV/pair 22 eV/pair (760 eV/ track) R* =40m 32 any pairs/track R=122m GEM response Test beam data 1D Cluster finder resolution

More Related