1. The STAR Upgrade Program Flemming Videbæk Brookhaven National Laboratory For the STAR collaboration Winter Workshop on Nuclear Dynamics, Feb 2013

2. Overview Introduction Near Term Upgrades – Muon Telescope Detector (MTD) – Realization & Planned Physics from MTD – Heavy Flavor Tracker (HFT) – Realization & Planned Physics from HFT Future Plans (STAR decadal Plan) – iTPC – Forward upgrades for pA and eRHIC Status and Summary 2/8/2013 2

3. Hot QCD matter: high luminosity RHIC II (fb -1 equivalent) – Heavy Flavor Tracker: precision charm and beauty – Muon Telescope Detector: e+μ and μ+μ at mid-rapidity – Trigger and DAQ upgrades to make full use of luminosity – Tools: jets combined with precision particle identification Phase structure of QCD matter: Beam Energy Scan Phase II – Fixed Target to access lowest energy at high luminosity – Low energy electron cooling to boost luminosity for √s NN <20 GeV – Inner TPC Upgrade to extend η coverage, improve PID Cold QCD matter: high precision p+A, followed by e+A – Major upgrade of capabilities in forward direction – Existing mid-rapidity detectors well suited for portions of e+A program 2/8/2013 3 How to explore QCD: from hot to cold

4. 2/8/2013 4 STAR: A Correlation Machine Tracking: TPC Particle ID: TOF Heavy Flavor Tracker (run 14) Electromagnetic Calorimetry: BEMC+EEMC+FMS (-1 ≤  ≤ 4) Muon Telescope Detector (runs 13/14) Plus upgrades to Trigger and DAQ Recent upgrades: DAQ1000 TOF Full azimuthal particle identification over a broad range in pseudorapidity Forward GEM Tracker (runs 12/13)

5. STAR near term upgrades Muon Telescope Detector (MTD) – Accessing muons at mid-rapidity – R&D since 2007, construction since 2010 – Significant contributions from China & India Heavy Flavor Tracker (HFT) – Precision vertex detector – Ongoing DOE MIE since 2010 – Significant sensor development by IPHC, Strasbourg 2/8/2013 5

6. 6 STAR-MTD physics motivation The large area of muon telescope detector (MTD) at mid-rapidity allows for the detection of Di-muon pairs from QGP thermal radiation, quarkonia, light vector mesons, resonances in QGP, and Drell-Yan production Single muons from the semi-leptonic decays of heavy flavor hadrons Advantages over electrons: no  conversion, much less Dalitz decay contribution, less affected by radiative losses in the detector materials, trigger capability in Au+Au collisions Trigger capability for low to high p T J/  in central Au+Au collisions and excellent mass resolution results in separation of different upsilon states e-muon correlation can distinguish heavy flavor production from initial lepton pair production

7. 2/8/2013 Concept of design of the STAR-MTD Multi-gap Resistive Plate Chamber (MRPC): gas detector, avalanche mode A detector with long-MRPCs covers the whole iron bars and leaves the gaps in- between uncovered. Acceptance: 45% at |  |<0.5 118 modules, 1416 readout strips, 2832 readout channels Long-MRPC detector technology, electronics same as used in STAR-TOF MTD 7

8. STAR-MTD 2/8/2013 8

9. MTD Performance from Run 12 Commissioned e-muon (coincidence of single MTD hit and BEMC energy deposition above a certain threshold) and di-muon triggers, event display for Cu+Au collisions shown above Determined the electronics threshold for the future runs, achieved 90% efficiency at threshold 24 mV Intrinsic spatial resolution: 2 cm 2/8/2013 e-muondi-muon p T (GeV/c) Y Resolution (cm) p T (GeV/c) Efficiency 9

10. Quarkonium from MTD 1.J/  : S/B=6 in d+Au and S/B=2 in central Au+Au collisions 2.Excellent mass resolution: separate different upsilon states 3.With HFT, study B  J/  X; J/    using displaced vertices Heavy flavor collectivity and color screening, quarkonia production mechanisms: J/  R AA and v 2 ; upsilon R AA … Z. Xu, BNL LDRD 07-007; L. Ruan et al., Journal of Physics G: Nucl. Part. Phys. 36 (2009) 095001 2/8/2013 10

11. Heavy Flavor Tracker (HFT) TPC Volume Outer Field Cage Inner Field Cage FGT 2/8/2013 11

12. Heavy Flavor Tracker (HFT) SSD IST PXL HFT Detector Radius (cm) Hit Resolution R/  - Z (  m -  m) Radiation length SSD2220 / 7401% X 0 IST14170 / 1800<1.5 %X 0 PIXEL 812/ 12~0.4 %X 0 2.512 / 12~0.4% X 0 SSD Existing single layer detector, double side strips (electronic upgrade) IST One layer of silicon strips along the beam direction (r-φ), guiding tracks from the SSD to PIXEL detector. - proven technology PIXEL two layers 18.4x18.4  m pixel pitch 10 sectors, delivering ultimate Pointing resolution that allows for direct topological identification of charm. New monolithic active pixel sensors (MAPS) technology 2/8/2013 12

13. PXL Detector Design Aluminum conductor Ladder Flex Cable Ladder with 10 MAPS sensors (~ 2×2 cm each) Carbon fiber sector tubes (~ 200µm thick) 20 cm The ladders will be instrumented with sensors thinned down to 50 micron Si. Novel rapid insertion mechanism allows effective exchanges and repairs (~12 h) Precision kinematic mount guarantees reproducibility to < 20 microns 2/8/2013 13

14. Production sector Production sector on metrology stage

15. Intermediate Si Tracker 2/8/2013 Details of wire bonding 24 ladders, liquid cooling Prototype Ladder S:N > 20:1 >99.9% live and functioning channels 15

16. Silicon Strip Detector (SSD) 4.2 Meters ~ 1 Meter 44 cm 20 Ladders Ladder cards 16 2/8/2013

17. Physics of the Heavy Flavor Tracker at STAR Direct HF hadron measurements (p+p and Au+Au) (1) Heavy-quark cross sections: D 0± *, D S, Λ C, B, … (2) Both spectra (R AA, R CP ) and v 2 in a wide p T region: 0.5 - 10 GeV/c (3) Charm hadron correlation functions, heavy flavor jets (4) Full spectrum of the heavy quark hadron decay electrons Physics (1) Measure heavy-quark hadron v 2, heavy-quark collectivity, to study the medium properties e.g. light-quark thermalization (2) Measure heavy-quark energy loss to study pQCD in hot/dense medium e.g. energy loss mechanism (3) Analyze hadro-chemistry including heavy flavors 2/8/2013 17

18. GEANT: Realistic detector geometry + Standard STAR tracking including the pixel pileup hits at RHIC-II luminosity Goal with Al-based cable (Cu cable -> 55 micron for 750 MeV/c K) DCA resolution performance r-ϕ and z 18 2/8/2013 0.4% X0

19. 19 2/8/2013 Physics – Run-14,15 projections R CP =a*N10%/N(60-80)% Assuming D 0 v 2 distribution from quark coalescence. 500M Au+Au m.b. events at 200 GeV. - Charm v 2  Medium thermalization degree Drag coefficients! Assuming D 0 R cp distribution as charged hadron. 500M Au+Au m.b. events at 200 GeV. - Charm R AA  Energy loss mechanism! Color charge effect! Interaction with QCD matter!

20. 20 2/8/2013 B tagged J/  Prompt J/  from B  Current measurement via J/  -hadron correlation have large uncertainties.  Combine HFT+MTD in di-muon channel  Separate secondary J/  from promptJ/   Constrain the bottom production at RHIC STAR arXiv: 1208.2736.

21. HFT project status HFT upgrade was approved CD-2/3 October 2011 and is well into fabrication phase All detector components have passed the prototype phase successfully A PXL prototype with 3+ sectors instrumented is planned for an engineering run and data taking in STAR in mid to end March The full assembly including PXL, IST and SSD should be available for RHIC Run-14, which is planned to be a long Au-Au run 2/8/2013 21

22. Future Plans Beam Energy Scan II ( Hui’s talk Monday) Exploit pA physics Prepare STAR for eRHIC on 2020-2025 timescale (eSTAR) 2/8/2013 22

23. Better tracking and dE/dx PID capability  1.0-1.7 region -- broad physics impact on transverse spin physics program hyperon and exotic particle searches high p T identified particles BES Phase II+ Long range rapidity gap correlations. 2/8/2013 23 Inner TPC Upgrade Current pad plane layout. 13 rows and gaps. Fill all inner sector with active pads. Configuration still under discussion

24. Some planned p+A measurements Nuclear modifications of the gluon PDF – Correlated charm production Gluon saturation – Forward-forward correlations (extension of existing π 0 -π 0 ) h-h π 0 -π 0 γ-h γ-π 0 – Drell-Yan Able to reconstruct x 1, x 2, Q 2 event-by-event Can be compared directly to nuclear DIS True 2  1 provides model-independent access to x 2 < 0.001 polarized protons off nuclei can be studied at RHIC. Forward-forward correlations and Drell-Yan are also very powerful tools to unravel the dynamics of forward transverse spin asymmetries – Collins vs Sivers effects, TMDs or Twist-3, … 2/8/2013 24 Easier to measure Easier to interpret

25. 2/8/2013 25 Forward instrumentation optimized for p+A and transverse spin physics – Charged-particle tracking – e/h and γ/π 0 discrimination – Possibly baryon/meson separation FHC (E864) ~ 6 GEM disks Tracking: 2.5 < η < 4 RICH/Threshold Baryon/meson separation proton nucleus 2017+ W-Powder EMCal FHC (E864) Pb-Sc HCal Forward Calorimeter System (FCS) Forward Instrumentation Upgrade

26. 2/8/2013 26 Calorimeter: 1)EM: Pb-glass (FMS) augmented by Tungsten SPACAL 1)Smaller Moliere radius for better 2-γ separation 2)Keep high E resolution 2)Hadron calorimetry for e/h discrim., jet reconstruction Very Forward GEM Tracker (VFGT) 1)Likely GEM-based 2)Details of the design depend on experience with FGT Particle Identification RICH problematic with accessible p T resolution Threshold Cerenkov detector under consideration Detector will not be included in initial upgrade Schedule : proposal this year, construction start 2015+ Ready for data 2017 at the earliest Plans for Forward Upgrade

27. Summary STAR has an ongoing upgrade program that will enable significant physics measurements in 2013-1017 Further high precision Heavy Flavor measurements will be carried out to explore the sQGP HFT upgrades will provide direct topological reconstruction for charm MTD will provide precision Heavy Flavor measurements in muon channels Future upgrades for 2017+ Enhanced TPC capabilities for BES II (and eSTAR) Forward Upgrades to exploit a p+A program – Full calorimetry (EM+Hadronic) – Modern tracking technology to make most of existing magnetic field Strong set of measurements to be made. Both complementary to, and supporting, those at a future eRHIC 2/8/2013 27

28. 2/8/2013 28 Backup

29. 2/8/201329 TPC TOF EMC HFT Neutral particles e, μ π K p d TPC TOF TPC Log 10 (p) Multiple-fold correlations among the identified particles! Nearly perfect coverage at mid-rapidity Hyperons & Hyper-nuclei Jets Heavy-flavor hadrons MTD High p T muonsJets & Correlations Charged hadrons Particle Identification in STAR

30. 30 What are the properties of cold nuclear matter? Is there evidence for saturation of the gluon density? PHENIX, Phys. Rev. Lett. 107, 172301 (2011) RHIC may provide unique access to the onset of saturation –Complementarity: LHC likely probes deeply saturated regime Future questions for p+A –What is the gluon density in the (x,Q 2 ) range relevant at RHIC? –What role does saturation of gluon densities play at RHIC? –What is Q s at RHIC, and how does it scale with A and x? –What is the impact parameter dependence of the gluon density? Upgrades to both STAR and PHENIX to extend observables (focus on EM) Timescale: medium-term (~2017+) STAR preliminary 2/8/2013

31. Measure charm correlation with MTD upgrade: cc bar  e+  An unknown contribution to di-electron mass spectrum is from ccbar, which can be disentangled by measurements of e  correlation. Simulation with Muon Telescope Detector (MTD) at STAR from cc bar : S/B=2 (M eu >3 GeV/c 2 and p T (e  )<2 GeV/c) S/B=8 with electron pairing and tof association 2/8/2013 31

32. Also measured: 1.Uniformity of response across the towers. 2. Energy resolution with and without mirror. 3. Perform scans along the towers with electrons and muons. 4. Estimated effects of attenuation and towers non-uniformities on resolution. 2/8/2013 32 Viable EMC detector technology developed through EIC R&D A prototype hadron calorimeter module will be built in 2013 Calorimeter: SPACAL works

33. 2/8/2013 33 p+A: Where to measure? Most promising at RHIC energies: y ~ 3-4 Q 2 ~ few GeV 2 N.B. Lines only schematic, kinematic control limited in p+A From 2->2 parton scattering, many sources of smearing LHC mid-y ~ RHIC y=4

34. MSC Pixel Insertion Tube Pixel Support Tube IDS East Support Cylinder Outer Support Cylinder West Support Cylinder PIT PST ESC OSC WSC Shrouds Middle Support Cylinder Inner Detector Support Inner Detector Support (IDS) Carbon Fiber Structures provide support for 3 inner detector systems and FGT. All systems are highly integrated into IDS. Installed for run-12 34 2/8/2013

35. Insertion check setup Two sector only shown in D-Tube (sector holding part). Next slides shows how this will be moved into position around the beam pipe (test setup). 2/8/2013 35

36. 2/8/2013 36 Tracking: proof of principle P t Resolution in STAR Forward TPC J. Putschke, Thesis Charged hadron R cp at |η|~3.1 |η|~3.1 nucl-ex/0703016 STAR magnetic field allows for moderate p T resolution in forward direction e.g. FTPC, position resolution ~100 μm Some added momentum resolution can be garnered from radial magnetic field at poletip Likely insufficient for RICH particle identification, but sufficient for charge sign discrimination in Drell-Yan: detailed simulations underway

37. STAR inner detector Support 2/8/2013 37

38. 38 2/8/2013 Charmed baryons (Lambda c) – Run-16  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, 222301 (2008)  Total charm yield in heavy ion collisions 38

39. 39 2/8/2013 Access bottom production via electrons particl e c  (  m) Mas s q c,b →x (F.R.) x →e (B.R.) D0D0 1231.86 5 0.540.067 1 D±D± 3121.86 9 0.210.172 B0B0 4595.27 9 0.400.104 BB 4915.27 9 0.400.109 Two approaches:  Statistical fit with model assumptions Large systematic uncertainties  With known charm hadron spectrum to constrain or be used in subtraction 39

40. 40 2/8/2013 Statistic projection of e D, e B R CP & v 2 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.  Unique opportunity for bottom e-loss and flow. - Charm may not be heavy enough at RHIC, but how is bottom? 40