HFT Trigger Needs for the Next 3-5 Years presented by Jim Thomas 09/14/2006

1. HFT Trigger Needs for the Next 3-5 Years presented by Jim Thomas 09/14/2006

2. The HFT: 2 layers of Si at mid rapidity The Heavy Flavor Tracker • A new detector • 30 mm silicon pixels to yield 10 mm space point resolution • Direct Topological reconstruction of Charm • Detect charm decays with small ct, including D0 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 • Physics Triggers closely associated with TPC tracking

3. 2 or more layers of Si at  = 0 3 or more layers of Si & GEMs at forward  Inner & Forward Tracking Upgrades • The ITUp will add high quality space points to tracks in the TPC • Si at h = 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 • Physics triggers associated with: • TPC tracks for HI • EEMC and BEMC towers for pp running

4. 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 )

5. Direct Topological Identification of Open Charm Goal: Put a high precision detector near the IP to extend the TPC tracks to small radius 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.

6. Triggers for HI Collisions • As appealing as it may sound, we probably won’t try to develop a level one (or two) trigger for D0’s (unless we can find someone who is very very clever …) • The MimoSTAR IV chip has a (dead-timeless) scan rate of 4 msec • The UltraSTAR chip can be triggered every 200 sec but is dead during the read cycle • The level 0 and level 1 working-times will expire before the data is ready. • Level III is a possibility. Will we have a level III trigger in the future? • And due to track/hit multiplicity considerations in HI collisions, we must have a TPC track to point at the ITUp and HFT detectors before we can associate hits with a track We need a TPC track to point at the Si detectors in order to associate hits from the HFT with a track

7. Triggers for HI Collisions • Two major themes when triggering on HI collisions with the HFT • We would like to trigger on (nearly) every physics event taken by the TPC. • The HFT physics triggers and TPC triggers are coupled • We will run calibration triggers and so would like a separate TCD unit • Testing of the HFT when the TPC is not running (or operational) • Cosmic muons with the beam off for calibration & alignment • Random triggers to see background events in the Si detectors Logically, the HFT trigger requires a TPC trigger for physics events. Electronically, we would like separate hardware for test and calibration.

8. Vertex Position Detector • We would like to see the collaboration invest in a high resolution VPD connection to the trigger • The HFT has a sweet spot in Z and so we would like to trigger on events with Z < 10 cm • A level II generated Z vertex position is a good idea, too, but it is better to have it at level 0 • The installation of the VPD does not have to wait for the HFT or the other ITUp detectors A high resolution VPD will benefit many different physics analyses and STAR sub-systems; including the TOF and the SVT

9. R&D is Driven by the Fabrication Schedule Driven by the availability of CMOS Active Pixel Sensors Build a full detector with each

10. HFT 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.

11. Install and run MimoSTAR IV Detector (Full) Install MimoSTAR III Ladder Install MimoSTAR IV Prototype Detector Install UltraSTAR Detector (Full) X X X X X 06 07 08 09 10 Install and test Prototype detector. Reduced diameter BP is required. HFT R&D and Installation Timeline Install MimoSTAR II Telescope R&D needs triggers, too. The full detector will arrive near the end of the 5 year timeline covered by this workshop. X marks the installation dates. Running comes after installation.

12. Addition Detail for the Trigger Group • The HFT electronics are concentrated in one small area near the beam pipe. We will probably only need one trigger and clock line from the trigger electronics. The fan-out can be done locally. • This will not be the case for the other ITUp detectors. Their electronics will be more distributed and so the trigger and clock fan-out should probably be done in the conventional way.

13. p-p Collisions • The forward tracking detectors may wish to participate in a fast trigger in p-p collisions • Intrinsically fast detectors • This will require additional thought when the design for the detectors is more fully developed • pp collisions present a lower multiplicity and occupancy in the detectors at large radius • So it may be possible to do a fast vertex trigger with the outer ITUp detectors (HPD, IST, SSD) in combination with the calorimeters • This will require additional thought when the design for the detectors is more fully developed

14. Summary • For HI collisions, the HFT is an extension of the TPC trigger as far as the trigger logic is concerned. • The HFT would like to have independent trigger hardware and trigger & clock lines • The outer Si detectors (HPD, IST, SSD) may wish to participate in a fast trigger in pp collisions • Homework

15. Supplementary slides

16. HFT Acceptance • Rapidity Bite is flat and ~ 2 units across the full Z of the detector • The Symmetric Acceptance is a function of Z • A symmetric acceptance of  0.4 units extends out beyond 7 cm • Thus we probably want to trigger on all events within 10 cm

17. Beam pipe

18. The SSD • 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