Global Track Trigger Technical

1. Global Track TriggerTechnical James Ferrando Glasgow For the GTT group J.Ferrando

2. Outline • Latency and deadtime in 2004 • Component data sizes in 2004 • Component data latency in 2004 • Trigger significance • Hardware modifications • Software plans and studies • Summary and Outlook J.Ferrando

3. GTT latency and deadtime in 2004 • Latency at GSLT is: • stable for GFLT output rates seen, • within CTD-SLT latency envelope, and • has a lower mean latency than the CTD-SLT • Deadtime does not appear to be introduced by the GTT, but… • Further study needs, per run, component GFLT deadtime numbers excluding external vetos. • Data source naming convention: • CTD = CTD axial+stereo data • CTDZ = CTD z-bz-time data • MVD= MVD data • MVD0,1, and 2 = upper, lower, and wheels • STT = STT data J.Ferrando

4. GTT component data sizes in 2004 • Data size cut at component interface used to control latency. If size exceeds cut, no data sent for event. • CTD and CTDZ both cut at 10kB • No event data is lost. • CTDZ data size not shown. • MVD cuts at 2kB • not all data sent - cut defined during bad background running in 2002. • renewed efforts to include MVD hits into barrel and forward algorithms mean: • the cut will gradually be increased, and • the MVD group will have to control bad channel readout. • STT cut at 6kB • more problematic than MVD as peak of distribution is not at low end. J.Ferrando

5. GTT component data latency in 2004 • Data ready latency at GTT • CTD and CTDZ latencies driven by CTD side TP data transfer and not by the GTT interface transfer. • MVD is usually quick, but tails driven by handling other triggers on the VME readout machines are evident. • STT latency should improve after the shutdown when more STT side TP readout links are used. J.Ferrando

6. Trigger significance • GTT currently working as an improved CTD-SLT • CTD and CTDZ data used, but MVD hits are not yet integrated into algorithms. • Z-vertex from initial forward algorithm showed no difference between NC and GSLT pass through events - use of MVD hits should improve this. • GTT quantities available and being studied by Physics groups: • Primary Z-vertex, • background rejection, and • J/Ψ selection J.Ferrando

7. GTT hardware modifications CTD stereo-axial • Separate CTDZ (z-by-time) component interface installed. • CTDZ tests made using the STT component interface crate. • Run# < 49376: MVD+CTD • 49376 < Run# < 49859: MVD+CTD+STT • Run# > 49860: MVD+CTD+CTDZ CTD z-by-time GSLT interface STT J.Ferrando

8. Software plans and studies • Started: • Improvement of the primary vertex finding algorithm which is currently based on the CTD-SLT algorithm - M.Bell. • Fill MVLDAQ bank allowing tie in with absolute timing at interfaces - A.Polini. • Split MVD data processing into 2 threads: barrel and forward - C.Youngman. • Starting Jan 2005 when manpower available: • Inclusion of MVD hits into barrel and forward algorithms and other tracking improvements (split tracks, etc.) - V.Roberfroid, M.Sutton, B.Straub. Studies required: • Data size, cut setting, bad channels, effect on trigger result, etc. • MVD hit weighting w.r.t. CTD and STT hits. • Improvements to DQM needed - N.N. ! • Ongoing studies: • Finalize performance (GTENV+MVLDAQ) monitoring - M.Bell. • Z-vertex efficiency - M.Bell, P.Allfrey, B.Straub + Physics groups. • Background rejection - B.Straub + Physics groups. • J/Ψ finding - B.Dunne, J.Ferrando + Physics groups. J.Ferrando

9. Summary and outlook • GTT performing well • inside CTD-SLT GSLT latency envelope. • mean latency significantly better than CTD-SLT • improved trigger quantities w.r.t. CTD-SLT • Improvements expected • Including MVD hits will: • significantly improve Z-vertex and track resolutions. • Lead to a useable forward algorithm. J.Ferrando