1 Jim Thomas - LBL HFT Issues that may Bear on the Fate of the SSD & SVT presented by Jim Thomas 07/07/2006

2 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 Desirable to have it in time for the next long Au-Au run Proposal moving forward The Heavy Flavor Tracker The HFT: 2 layers of Si at mid rapidity

3 Jim Thomas - LBL Direct Topological Identification of Open Charm The STAR HFT 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

4 Jim Thomas - LBL Surround the vertex with Si A thin detector using 50  m Si to finesse the limitations imposed by MCS

5 Jim Thomas - LBL The HFT has a Distinguished R&D Heritage Driven by the availability of CMOS Active Pixel Sensors Mimosa-1Mimosa-4Mimosa-8MimoSTAR-1MimoSTAR-2MimoSTAR-3MimoSTAR-4UltraSTAR Build a full detector with each

6 Jim Thomas - LBL The Need for Substantial R&D Challenging HFT technologies –The Silicon Chips –Further refinement of on-chip electronics –Readout Electronics –speed, heat dissipation, compatibility with STAR DAQ –The Mechanical Arms to insert the detector –Alignment and stability –Calibration, Tracking & Software –New levels of precision –The beam pipe –Smaller than ever before … Operation and robustness

7 Jim Thomas - LBL Schedule for R&D and Construction of the HFT

8 Jim Thomas - LBL HFT R&D Installation for the Summer of 2006 A Three Layer Telescope with MimoSTAR II Chips. A full system test from pixel to DAQ.

9 Jim Thomas - LBL Beam pipe The exo-skeleton for the new beam pipe is incompatible with inner radius of the SVT. This conflict determines the final date when the SVT must be moved.

10 Jim Thomas - LBL HFT Timeline vis a vis the SVT 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. Highly desirable to install and test with reduced diameter BP Reduced diameter BP is required. SVT must be out of the way

11 Jim Thomas - LBL SVT Detail – beam pipe size & mounting issues …

12 Jim Thomas - LBL

13 Jim Thomas - LBL SVT Recommendations It would be fun to do HFT R&D with the SVT. Ideally, we would remove the first layer of the SVT and install HFT chips inside this region. –Long, difficult task but there do not appear to be the human resources to do it (nor financial). Therefore I recommend: Remove the SVT in the summer of 2008 so we can do HFT prototype detector tests at the IP –This ensures a success scenario for the HFT If this is not possible, the SVT must come out in the summer of 2009 so we can install the reduced diameter BP and a full version of the MimoSTAR IV detector

14 Jim Thomas - LBL The SSD is a Beautiful Detector The SSD is thin –1% - double sided Si The SSD lies at an ideal radius –23 cm - midway between IP and IFC The SSD has excellent resolution –(rumor says better than design) The SSD is too large to be replaced –The money is better spent, elsewhere

15 Jim Thomas - LBL A Toy Model for Pointing at the HFT including P T and DCA Resolution Jim Thomas Lawrence Berkeley National Laboratory November 29 th, 2005

16 Jim Thomas - LBL To Make a Long Story Short … Covariance matrix equations from the particle handbook Include errors due to finite spectrometer resolution Include errors due to Multiple Coulomb Scattering –Due to MCS limitations, it is the previous two layers that determine the pointing resolution on the current layer – so a 2 layer approximation is a very good approximation for extremely high resolution detectors.

17 Jim Thomas - LBL TPC p T Resolution in 2001 (Half field data) Pions in the TPC without the SSD or SVT p-bars in the TPC without the SSD or SVTAdd the SSD and the SVT; resolution improves but MCS gets worse Add a 350  m vertex constraint

18 Jim Thomas - LBL Pointing resolution at the next Detector TPC Pointing at the SSD TPC Pointing at the SSD with 350  m Vertex Constraint TPC & SSD Pointing at the HFT TPC & SSD Pointing at the HFT with 100  m Vertex Constraint

19 Jim Thomas - LBL SSD Issues & Recommendation Positives The HFT needs the SSD (or something equivalent) as part of the pointing package. It points at the intermediate tracker and reduces the search radius for finding hits. It is the third layer in the pointing system. Very important for overall tracking efficiency because any given layer is only ~90% efficient. –Two layers are 80% efficient –But three layers are 97% efficient for having two hits A third layer provides badly needed redundancy and insurance that we are successful in putting data on tape Negatives It will have to be remounted on a new ‘cone’ It will need new electronics to keep up with DAQ 1000 These appear to be good investments SSD Recommendation: Keep It!