1. 1 Heavy flavor physics and  Vertex detector

2. 2 People involved RNC Group Howard Wieman Hans-Georg Ritter Fred Bieser (Lead Electronic Engineer) Howard Matis Leo Greiner Fabrice Retiere Eugene Yamamoto Kai Schweda Markus Oldenburg Robin Gareus (Univ. of Heidelberg) LEPSI/IReS (Strasbourg) Claude Colledani, Michel Pellicioli, Christian Olivetto, Christine Hu, Grzegorz Deptuch Jerome Baudot, Fouad Rami, Wojciech Dulinski, Marc Winter UCIrvine Stuart Kleinfelder + students LBNL Mechanical Engineering Eric Anderssen (consultation – ATLAS Pixels) Design works BNL Instrumentation Div (consulting) Ohio State U Ivan Kotov

3. 3 Heavy flavor in ultra-relativistic heavy-ion collisions Heavy Q pair formation How many? c/b quarks in matter Thermalization? Coalescence? Flow? Heavy flavor hadrons to detectors Heavy quark energy loss High p T Low Intermediate p T

4. 4 Measuring yields Large uncertainties In data In theory Way to improve Measure and identify all charm hadrons Measure precise spectra STAR preliminary

5. 5 Heavy-quark energy loss p + p d + Au p + p d + Au p + p d + Au Heavy quarks radiate less energy than light quarks (prediction) Yield of charm and beauty (leading) hadrons less suppressed May be measured by D → X+e- and B → X+e- Without vertex information systematic error from background substraction STAR preliminary

6. 6 Flow and thermalization Flow: spectra and v 2 Charm thermalization by chemistry J. Nagle, S. Kelly, M. Gyulassy, S.B. JN, Phys. Lett. B 557, pp 26-32 e-p & e + e - Thermal f(c→D 0 )0.5570.483 f(c→D + )0.2320.21 f(c→D s + )0.1010.182 f(c→  c + ) 0.0760.080

7. 7 Measuring heavy flavor with the  Vertex detector Goals Heavy flavor energy loss Remove background Charm flow Precise D 0 spectra D 0 v 2 Charm thermalization Yield of D +, D s +,  c + (challenging 3 body decays)  Vertex strategy Separate charm and beauty decay product from primary tracks Typically D 0 c  = 124  m  Vertex requirement: a very good vertex resolution Position resolution < 10  m Thickness < 0.2% of rad length to limit multiple scattering

8. 8 STAR  Vertex Detector Two layers 1.5 cm radius 4 cm radius 24 ladders 2 cm by 20 cm each < 0.2% X 0 ~ 100 Mega Pixels

9. 9 Charm hadron reconstruction performances System N events for 3  D 0 signal N events for 3  D + s signal In progress TPC+SVT12.6 M~500 M (K 0 s + K + ) TPC+SVT+TOF2.6 M ~1,000 M (  +  + ) TPC+SVT+  Vertex100 K ~100 M (  +  + ) TPC+SVT+  Vertex+TOF10 K ~1 M (  +  + )

10. 10 STAR  Vertex Detector New vertex detector centered in existing SVT, supported one end only End view showing 3 of 6 ladder modules

11. 11 Support: thin stiff ladder concept Under development Will be tested for vibration in our wind tunnel carbon composite (75  m) Young’s modulus 3-4 times steel aluminum kapton cable (100  m) silicon chips (50  m) 21.6 mm 254 mm

12. 12 Sensors: Active Pixel Sensors Advantages Precise Can be thin Rather fast Low power Disadvantages Small signal Not that fast New Need R&D p-well n-well p-epi p-substrate 5-20  m CMOS electronic Analog & digital

13. 13 Sensors: 2 generations 1 st Generation: 5-10 ms readout time MIMOSTAR1 designed by LEPSI/IRES (Strasbourg) 640*640 pixel of 30*30  m 2 pitch Purely analog Parallel readout on-chip multiplexed to 2 kind of outputs 1 * 100MHz driver 10 * 10 MHz drivers 2 nd Generation: Faster but need more R&D R&D with UCIrvine and LEPSI/IRES Improve charge collection and remove need for CDS Photogate, Active reset, … Some digital processing Up to cluster-finder?

14. 14 Readout Analog to end of the ladder (~1 m away) Challenge to drive analog signal at 100 MHz over 1m Piggy back chip ADC and memory on a chip bounded to the pixel chip On-chip processing in 2 nd generation Data reduction at the end of the ladder Hardware reduction (zero suppression) Single board computer

15. 15 Budget FY02-FY04 LBNL LDRD (total 375K$) FY04 RHIC R&D (200 K$ through Brookhaven) Expected to continue until project is funded Preparing a strategic LDRD fund request geared towards the development of future tracking apparatus with the Physics Division (Linear Collider)

16. 16 The time-scale Proposal in April 2004 1 st ladder prototype this fall (2004) Investigate mechanical support, cabling and some readout issues Sensor: MIMOSA5 large but slow and “noisy” 2 nd ladder prototype next year (fall 2005) Sensor: MIMOSTAR1 (submitted in July) R.Gareus’s Readout chip (submitted in July) The real thing starting in 2006 Pending funding and success of prototypes

17. 17 Summary A lot of work ahead of us!