1 Jim Thomas - LBL STAR Inner Tracking Upgrades with an emphasis on the Heavy Flavor Tracker presented by Jim Thomas Lawrence Berkeley Laboratory 11 / 08 / 2006

2 Jim Thomas - LBL The Light Quark Program at STAR is Compelling Lattice results Its hot Its dense and it flows at the partonic scale  and , too! Spectra VnVn Jets & R cp Now we can make these measurements in the charm sector

3 Jim Thomas - LBL Heavy Flavor Energy Loss … R AA for Charm Heavy Flavor energy loss is uncertain –Gluon densities up to 3500 are insufficient to describe the data –~ 1000 from light quark data Beauty dominates single electron spectra above 5 GeV and makes the model worse M. Djordjevic, et. al. nucl-th/ Current energy loss mechanisms can only account for part of the strong suppression of R AA for electrons

4 Jim Thomas - LBL Flow: Constituent Quark Number Scaling In the recombination regime, meson and baryon v 2 can be obtained from the quark v 2 : Does it work in the Charm Sector? A strong test of the theory

5 Jim Thomas - LBL Elliptic Flow with Charm M. Kaneta (PHENIX), J. Phys. G: Nucl. Part. Phys. 30, S1217 (2004). D  e +X Single electron spectra from PHENIX show hints of elliptic flow The HFT will cut out large photonic backgrounds:   e+e- and reduce other large statistical and systematic uncertainties STAR can make this measurement with 50 M Au+Au events in the HFT Smoking gun for thermalization at RHIC! Better if we can do direct topological identification of Charm

6 Jim Thomas - LBL Single Electron Spectra … are not sufficient Hydro and Pythia are extreme models on opposite ends of the model spectrum –Charm in red, Beauty in Blue … Hydro is the solid line, Pythia is dashed Single electron spectra are not sufficient to distinguish hard and soft physics below 3 GeV –We will also see this in the R AA measurements The decayed spectra are shown in black and are nearly indistinguishable We heard this message many times at QM05 and will hear it again at QM06 S. Batsouli et al., Phys. Lett. B 557 (2003) 26. We need direct topological identification of Charm

7 Jim Thomas - LBL Direct Topological Identification of Open Charm The STAR Inner Tracking Upgrades will identify the daughters in the decay and do a direct topological reconstruction of the open charm hadrons. No Mixed events, no random background subtraction. Goal: Put a high precision detector near the IP to extend the TPC tracks to small radius

8 Jim Thomas - LBL A new detector –30  m silicon pixels to yield 10  m space point resolution Direct Topological reconstruction of Charm –Detect charm decays with small c , including D 0  K  New physics –Charm collectivity and flow to test thermalization at RHIC –Charm Energy Loss to test pQCD in a hot and dense medium at RHIC R&D with HFT + SSD A proposal has been submitted and a TDR is in preparation The Heavy Flavor Tracker The HFT: 2 layers of Si at mid rapidity

9 Jim Thomas - LBL Inner & Forward Tracking Upgrades The Inner Tracking Upgrade include –HPD (1 layer) –IST (2 layers) The ITUp will add high quality space points to tracks in the TPC –Si at  = 0 The FTUp will add high quality space points at forward η –1 < η < 2 High Rate tracking for heavy flavor physics and W production 3 or more layers of Si & GEMs at forward  2 or more layers of Si at  = 0

10 Jim Thomas - LBL 2 options for the location of Triple-GEM detectors (Barrel or Disk configuration) B. Surrow et al., Nucl. Instr. and Meth. B241 (2005) 293. e + /e - Forward Tracking Upgrade Polarized pp program at √s = 500 GeV at RHIC at BNL: –Study the proton spin flavor structure of the proton spin W detection via W   e  decay –identification of the e  charge sign is critical Employ triple-GEM detectors as part of STAR tracking upgrade –Low dead material, fast time response, precise hit determination, cost effective –Barrel or Disk configuration With 4 conventional silicon disks in the forward direction

11 Jim Thomas - LBL Surround the Vertex with Si The HFT is a thin detector using 50  m Si to finesse the limitations imposed by MCS Add the HPD, IST, and SSD to form the STAR Inner Tracking Upgrade ( ITUp )

12 Jim Thomas - LBL ~ 1 m Inside the IFC –Goal: graded resolution from the outside – in –TPC – IST – HPD – HFT –TPC pointing resolution at the SSD is ~ 1 mm –SSD pointing at the IST is ~ 300  m –IST pointing at the HPD is ~ 150  m –HPD pointing at the HFT is ~ 100  m –HFT pointing at the VTX is ~ 50  m

13 Jim Thomas - LBL SSD ~ 60 cm –Double sided Si wafers 300  m thick with 95  m x 4.2 cm strips –Crossed at 35 mrad – effectively 30  m x 900  m –One layer at 23 cm radius –20 ladders, 67 cm long –air cooled –  < 1.2 –1 % radiation  = 0

14 Jim Thomas - LBL IST ~ 36 cm –Singled sided Si wafers 300  m thick with 60  m x 4.0 cm strips –Si pads ~ 1 mm**2 on the other side of each ladder –Two layers at 17 & 12 cm radius –27 ladders, 52 cm long –19 ladders, 40 cm long –air cooled –  < 1.2 –1.5 % per  = 0

15 Jim Thomas - LBL HPD ~ 22 cm –ALICE Hybrid Pixels 350  m thick, with 250  m in the sensor and 150  m in the ASIC –50  m x 425  m strips –One layer at 9.1 cm radius –48 ladders, 28 cm long –C 6 F 14 Evaporative cooling –  < 1.2 –1.1 % radiation  = 0

16 Jim Thomas - LBL HFT ~ 17 cm –Active Pixel Sensors, thinned to 50  m thickness –30  m x 30  m pixels –Two layers at 7 & 2.5 cm radius –24 ladders, 19.2 cm long – 9 ladders, 19.2 cm long –air cooled –  < 1.2 –0.28 % radiation  = 0

17 Jim Thomas - LBL R&D in Run 7 A Three Layer Telescope with MimoSTAR II Chips. A full system test from pixel to DAQ using an extension of one TPC sector trigger line.

18 Jim Thomas - LBL HFT R&D and Installation Timeline Install MimoSTAR II Telescope XXXXX Install MimoSTAR IV Prototype Detector Install MimoSTAR III Ladder Install and run MimoSTAR IV Detector (Full) Install UltraSTAR Detector (Full) Install and test Prototype detector. Reduced diameter BP is required. X marks the installation dates. Running comes after installation. Proposed HFT Timeline – the HPD and IST come about 1 year later

19 Jim Thomas - LBL A Rich Physics Program There is a rich physics program when all of the STAR physics detectors are working together –Flow in the Charm sector –dE/dx in the Charm sector –Recombination and R AA in the Charm sector –Vector Mesons –Charm Angular Correlations –non-photonic electrons –…

20 Jim Thomas - LBL Working with the rest of STAR … ( ) n Combining the power of the STAR TOF barrel to identify electrons with the ability of the TPC and Inner Tracking Upgrades to identify and eliminate conversion electrons means we can execute a vigorous single electron and di-electron program of measurements

21 Jim Thomas - LBL Summary The STAR Inner Tracking Upgrade will explore the Charm sector We will do direct-topological-reconstruction of open Charm Our measurements will be unique at RHIC The key measurements include –V 2 –Energy Loss –Charm Spectra, R AA & R cp –Vector mesons –Angular Correlations The technology is available on an appropriate schedule

22 Jim Thomas - LBL Supplementary slides

23 Jim Thomas - LBL Si Pixel Developments in Strasbourg Mimosa – 1 –4k array of 20  m pixels with thick epi layer Mimosa – 4 –Introduce Forward Biased Diode Mimosa – 5 –1M array of pixels, 17  m pixels using AMS 0.6 process –4 msec readout scan rate Mimosa – 8 –Fast parallel column readout with internal data sparsification –200  sec readout scan rate –MimoSTAR – 1 128x128 pixels using TSMC 0.25 –MimoSTAR – 2 128x128 pixels using AMS 0.35 –Duct tape these to the STAR Beam Pipe for 07 run –MimoSTAR – 3320x640 pixels using AMS 0.35 –MimoSTAR – 4 640x640 pixels production run –Ultra – 1 –Ultra – 2

24 Jim Thomas - LBL Addition Detail

25 Jim Thomas - LBL Copy the Alice HPD using only one layer

26 Jim Thomas - LBL HPD Ladders - Sector Layout Image: INFN Padova HPD total ~ 1000 pixel chips, ≈ 10 7 pixels Kapton cables MCM RDO section active area

27 Jim Thomas - LBL HPD Ladder Cross-Section 7-layer Aluminum Kapton Flex 200  m 150  m M. Morel