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Future Heavy Flavor Program at STAR

Future Heavy Flavor Program at STAR. Xin Dong for the STAR Collaboration Lawrence Berkeley National Lab. LHC. Heavy Ion Frontiers. 1 Quantify the medium properties. Outline. Physics Motivations STAR Approach and Detector Upgrade Plans Physics Capabilities of Future HF Measurements

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Future Heavy Flavor Program at STAR

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  1. Future Heavy Flavor Programat STAR Xin Dong for the STAR Collaboration Lawrence Berkeley National Lab

  2. LHC Heavy Ion Frontiers 1 Quantify the medium properties

  3. Outline • Physics Motivations • STAR Approach and Detector Upgrade Plans • Physics Capabilities of Future HF Measurements • Summary

  4. What we’ve learned • High pT: • Jet quenching • Low pT: • Hydrodynamic behavior • Multi-strange hadrons flow • Intermediate pT: • Number of Constituent Quark scaling • Multi-strange hadrons flow as light hadrons A hot and dense matter with strong partonic collectivity has been formed at RHIC! STAR: NPA 757, 102 (2005); QM2009

  5. Heavy Quark E in hot QCD medium STAR PRL 98 (2007) 192301 • Heavy quark decay electrons - mixture of charm and bottom decays • RAA(e) ~ RAA(h) • Contradict to the naïve radiative energy loss mechanism • Re-visit the energy loss mechanisms • Require direct measurements of charm or bottom hadrons for clear understanding

  6. Heavy Quarks to Probe Early Thermalization B. Mueller, nucl-th/0404015 • Heavy quarks created at early stage of HIC, and sensitive to the partonic re-scatterings. • Heavy quark collectivity/flow to quantify the thermalization degree at the top energy. • Thermalization - essential to the RHIC Beam Energy Scan program. charm quarks

  7. T/TC 1/r[fm-1] (1S) 2 b(1P) 1.2 J/(1S) ’(2S) b’(2P) ’’(3S) TC c(1P) ’(2S) A. Mocsy & P.Petreczky, PRL 99 (2007) 211602 Heavy Quarkonia - QGP Thermometer • Quarkonia suppression due to color screening - a classic QGP signature • T. Matsui and H. Satz, PLB 178 (1986) 416 • Sequential dissociation - Quarkonia as a QGP thermometer • H. Satz, NPA 783 (2007) 249c; A. Mocsy & P. Petreczky, PRL 99 (2007) 211602 2-Flavor QCD O. Kaczmarek & F. Zantow, PRD 71 (2005) 114510

  8. STAR Approach • Detection capability at mid-rapidity, full azimuth • large and uniform acceptance • allowing precision correlation measurements • 1) Direct topological reconstruction of open charmed hadrons in HI collisions • No ambiguities in the charm hadron kinematics • No ambiguities in the charm/bottom hadron mixture • Significantly improved significance by reconstructing the secondary decay vertices. • 2) Quarkonia measurements via both di-electron/di-muon channels • Triggerable di-muon channel to sample full luminosity • No bremmestrahlung tail in di-muon channel so allow separation of three Upsilon states STAR Decadal Plan Documents: http://www.bnl.gov/npp/docs/STAR_Decadal_Plan_Final%5B1%5D.pdf

  9. STAR Detector

  10. |1/-1|<0.03 Full Barrel Time-Of-Flight • Full barrel completed for Run 10. • Extended hadron PID to intermediate pT • TOF/TPC allows electron PID down to very low momentum • Bring benefits to both open HF and quarkonia program in the future.

  11. Heavy Flavor Tracker (HFT) HFT SSD IST PXL Inner Field Cage Magnet Return Iron FGT Outer Field Cage TPC Volume Solenoid EAST WEST

  12. Heavy Flavor Tracker • SSD existing single layer detector, double side strips (electronic upgrade) • IST one layer of silicon strips along beam direction, guiding tracks from the SSD through PIXEL detector. - proven strip technology • PIXEL double layers, 18.4x18.4 m pixel pitch, 2 cm x 20 cm each ladder, 10 ladders, delivering ultimate pointing resolution. - new active pixel technology HFT consists of 3 sub-detector systems inside the STAR Inner Field Cage (IFC)

  13. Pixel Geometry End view 8 cm radius 20 cm 2.5 cm radius Inner layer Outer layer total 40 ladders  coverage +-1 One of two half cylinders

  14. Some pixel features and specifications critical and difficult more than a factor of 3 better than other vertex detectors (ATLAS, ALICE and PHENIX)

  15. Muon Telescope Detector (MTD) A detectorwith long-MRPCs covers the whole iron bars and leave the gaps in- between uncovered. Acceptance: ||<0.5 and 45% in azimuth 118 modules, 1416 readout strips, 2832 readout channels Long-MRPC detector technology, HPTDC electronics (same as STAR-TOF)

  16. MTD (Run 10 Prototype) Performance pure muons pT: ~6 GeV/c σ: 109 ps • Total resolution: 109 ps • MTD intrinsic resolution: 96 ps • satisfying the design goal • System spatial resolution: 2.5 cm, dominated by multiple scattering • expected from simulation σ: 2.5 cm position difference (cm)

  17. MTD Detecting Probes • di-muon pairs from heavy quarkonia decays • single muons from thesemi-leptonic decays of heavy flavor hadrons • e-mu correlations to distinguish HF production from initial di-lepton production • Advantages over electron channels: • no  conversion, much less Dalitz decay contribution • Much less combinatorial background • less affected by radiative losses in the detector materials • excellent mass resolution, allowing separation of three Upsilon states • triggerable in Au+Au • sample full luminosity from low to high pT for J/ in central AA collisions

  18. 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 … DAQ1k TOF HFT MTD RHIC II Upgrade Schedule

  19. Future Open HF Measurements HFT + TPC + TOF topological reconstruction of all ground state charmed hadrons HFT + TPC + TOF + EMC/MTD single electron/muon from semi-leptonic decays of charm/bottom hadrons - with HFT allows to separate charm/bottom contributions e or mu induced correlation measurements

  20. Physics Projections RCP=a*N10%/N(60-80)% Assuming D0 v2 distribution from quark coalescence. 500M Au+Au m.b. events at 200 GeV. - Charm v2 Thermalization degree! Drag coefficients! • Assuming D0 Rcp distribution as charged hadron • 500M Au+Au m.b. events at 200 GeV. • Charm RAA • Energy loss mechanism! • Interaction with QCD matter!

  21. Charm Baryons • cpK Lowest mass charm baryons c = 60 m • c/D enhancement? • 0.11 (pp PYTHIA)  0.4-0.9 (Di-quark correlation in QGP) S.H. Lee etc. PRL 100 (2008) 222301 • Total charm yield in heavy ion collisions

  22. HQ decay electrons spectra/v2 Charm hadron spectra/v2 Charm decay electron spectra/v2 Bottom decay electron spectra / v2 Access Bottom Production via Electrons (b) (a) Two approaches: Statistical fit with model assumptions With known charm hadron spectrum to constrain or be used in subtraction

  23. Statistical Projections on eB Spectra / v2 Curves:  H. van Hees et al. Eur. Phys. J. C 61 (2009) 799 • (Be) spectra obtained via the subtraction of charm decay electrons from inclusive NPEs: no model dependence, reduced systematic errors.

  24. e-mu correlations ccbar Drell-Yan Thermal radiation L. Ruan et al., JPG 36 (2009) 095001 e correlation with Muon Telescope Detector at STAR from ccbar: S/B=2 (Meu>3 GeV/c2 and pT(e)<2 GeV/c) S/B=8 with electron pairing and tof association

  25. Heavy Quarkonia Program A) Up to 2013 (TPC+TOF+EMC) Charmonia: low pT from minibias sample - limited statistics high pT from single electron HT trigger - efficient and can sample the full luminosity will carry on at RHIC II Bottomonia: di-electron channel - material effect from inner tracker / limited statistics B) 2014 and beyond (HFT+TPC+TOF+EMC+MTD) Charmonia: di-muon channel covers from low to high pT high pT from single electron HT trigger Bottomonia: di-muon channel - excellent in mass resolution and able to sample full luminosity di-electron channel within HFT acceptance - limited statistics

  26. Heavy Quarkonia via di-electrons STAR, PRC80 (2009) 041902(R) R. Reed, HP 2010  J/ Run7 AuAu 300 ub-1 Run 6 p+p 8 pb-1 Run 7 Au+Au 300 ub-1 Run 9 p+p 20 pb-1 Run 10 Au+Au 1.4 nb-1 Single electron HT trigger to reach high pT J/ Limited statistics -> Multi year physics program

  27. J/ with MTD J/ efficiency • muon efficiency at |η|<0.5: 36%, pion efficiency: 0.5-1% at pT>2 GeV/c • dimuon trigger enhancement factor from online trigger: 40-200 in central Au+Au collisions

  28. Upsilon Mass Resolution with MTD Di-electrons with material from inner tracker Di-electrons with no material from inner tracker Di-muons from any case 2008 to 2013: di-electrons are a good probe for Upsilons however, limited by statistics / luminosity 2014 - : di-electrons suffer from inner HFT material - hard to separate three states di-muons will be a great probe to measure different Upsilon states with RHIC II

  29. J/ Υ J/ Projections on Quarkonia Measurements J/ RAA and v2 ΥRAA vs. Npart

  30. BJ/ + X with HFT+TPC+MTD Prompt J/ J/ from B • HFT to separate B decay J/ from prompt J/ • MTD to reconstruct J/ from di-muon decays

  31. Charm to Probe Nucleon/Nucleus Structure K.Kurek, Spin Workshop @LBL 2009

  32. Summary Heavy flavor physics will be one of the key measurements in quantifying the medium properties at the RHIC II era. STAR HFT and MTD upgrades together with existing subsystems allow precision measurements on both open heavy flavor and quarkonia production at mid-rapidity with RHIC II luminosities. • STAR Decadal Plan: • http://www.bnl.gov/npp/docs/STAR_Decadal_Plan_Final%5B1%5D.pdf • Continue the ongoing heavy ion and spin programs with pp, pA and AA • Complement with ep and eA programs / evolve to eSTAR@eRHIC

  33. BACKUP SLIDES

  34. DOE milestone 2016 Measure production rates, high pT spectra, and correlations in heavy-ion collisions at sNN = 200 GeV for identified hadrons with heavy flavor valence quarks to constrains the mechanism for parton energy loss in the quark-gluon plasma

  35. Charm Quark Hadronization Direct (hard) fragmentation in elementary collisions. However, in heavy ion collisions … • Coalescence approach V. Greco et al., PLB 595(2004)202 Charm baryon enhancement ? - coalescence of c and di-quark Lee, et. al, PRL 100 (2008) 222301

  36. Charm cross section STAR, PRL 94 (2005) 062301, arXiv: 0805.0364, QM08 PHENIX, PRL 96 (2006) 032001, 96 (2006) 032301, 97 (2006) 252002, PRD 76 (2007) 092002, QM08 • Big experimental (statistical & systematical) uncertainties • Extrapolated from electron channel • Hadronic channel suffered huge combinatorial background • No knowledge about charm chemistry • Need precision measurements on various charm hadrons via displaced vertices

  37. Electrons - Incomplete Kinematics New micro-vertex detector is needed for precision measurements on charmed hadrons production in heavy ion collisions

  38. Summary MTD will advance our knowledge of Quark Gluon Plasma: trigger capability for low to high pT J/ in central Au+Au collsions excellent mass resolution, separate different upsilon states e-muon correlation to distinguish heavy flavor production from initial lepton pair production rare decay and exotics … different background contribution provides complementary measurements for dileptons The prototype of MTD works at STAR from Run 7 to Run 10. Results published at L. Ruan et al., Journal of Physics G: Nucl. Part. Phys. 36 (2009) 095001; 0904.3774; Y. Sun et al., NIMA 593 (2008) 430. muon purity>80%; the primary muon over secondary muon ratio: good for quarkonium program the trigger capability with L0 and L2: promising for dimuon program: Upsilon, J/ elliptic flow v2 and RAA at high pT The larger Run 11 modules with slightly wider readout strips show a comparable performance as the modules in Runs 7-10, based on cosmic ray tests at USTC and Tsinghua.

  39. Monolithic Active Pixel Sensor (MAPS) from IPHC Commercial CMOS technology Thin - 50 m silicon Small pixels, high resolution Fast readout Air cooling Mechanical stability Pixel Technology pointing accuracy comparison Hybrid uncertainty area -------------------------------- MAPS uncertainty area Hybrid: 50 x 450 1.2% X0 MAPS: 18.4 x 18.4 0.37% X0

  40. Alternate Technologies Considered • Hybrid • X0 large (1.2%) • Pixel Size large (50 m x 450 m) • Specialized manufacturing - not readily available • CCDs • Limited radiation tolerance • Slow frame rate, pileup issues • Specialized manufacturing • DEPFET • Specialized manufacturing • very aggressive unproven technology

  41. Pointing Resolution Performance Mean pT 30 m 2 2 GEANT: Realistic detector geometry + Standard STAR tracking including the pixel pileup hits at RHIC-II luminosity Hand Calculation: Multiple Coulomb Scattering + Detector hit resolution PXL telescope limit: Two PIXEL layers only, hit resolution only

  42. Reconstruction of Displaced Vertices D0 decays Direct topological reconstruction of charm and bottom decays

  43. Efficiency / Significance Need New plots D0 spectrum covering 0.5 - ~10 GeV/c in one RHIC run

  44. Al vs. Cu Cable Thin: Aluminum (0.37% X0) Thick: Copper (0.52% X0) Aluminum cable will improve the low pT significance by ~ 1.5 - running time need to be ~ 2 times longer to achieve the same precision

  45. More Charm Hadrons D+K Mass = 1.869 MeV c=312m

  46. B capability -- electron channels B.R. = Branching Ratio F.R. = Fragmentation Ratio Pixel layers 1) Be = NPE  De 2) The distance of closest approach to primary vertex (dca): Due to larger c, B e has broader distribution than D  e Dca of D+ e is more close to that of B  e. need more constraint. dca: the distance of closest approach to primary vertex dca

  47. Statistical Projections on eB Spectra Need update Curves:  H. van Hees et al. Eur. Phys. J. C61, 799(2009). • (Be) spectra obtained via the subtraction of charm decay electrons from inclusive NPEs: no model dependence, reduced systematic errors.

  48. Statistical Projections on eB v2 Need update Assuming D meson v2 from quark coalescence (curves). r  v2(eB) + (1-r)  v2(eD) = v2(NPE) r is the eB/(eD+eB) ratio v2(eD) is D e v2 v2(eB) is B e v2 , which can be extracted from this equation. Dashed-curves: Assumed D0-mesom v2(pT) - in coalescence model Symbols: D decay e v2(pT) Vertical bars: errors for b decaye v2(pT) from 200 GeV 500M minimum bias Au + Au events

  49. Compelling Physics with HFT The STAR HFT measurements (p+p and Au+Au)(1) Heavy-quark cross sections: D0,±,*, DS, C , B… (2) Both spectra (RAA, RCP) and v2 in a wide pT region. (3) Charm hadron correlation functions (4) Full spectrum / v2 of the heavy quark hadron (separated) decay electrons 2) Compelling Physics Establish elementary charm and bottom cross sections Characterize the medium through parton energy loss Determine the degree of thermalization via heavy quark flows Analyze hadro-chemistry in the charm sector Study the bottom behavior in medium via the separation of charm contributions

  50. STAR HFT vs. PHENIX VTX

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