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Some thoughts on the New Small Wheel Trigger Issues

Some thoughts on the New Small Wheel Trigger Issues. V. Polychronakos, BNL 10 May, 2011. The Problem with High pT Triggers. Current Endcap Trigger Only a vector BC at the Big Wheels is measured Momentum defined by implicit assumption that track originated at IP

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Some thoughts on the New Small Wheel Trigger Issues

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  1. Some thoughts on the New Small Wheel Trigger Issues V. Polychronakos, BNL 10 May, 2011

  2. The Problem with High pT Triggers • Current Endcap Trigger • Only a vector BC at the Big Wheels is measured • Momentum defined by implicit assumption that track originated at IP • Random background tracks can easily fake this • ProposedTrigger • Provide vector A at Small Wheel • Powerful constraint for real tracks • With pointing resolution of 1 mradit will also improve pT resolution • Currently 96% of High pT triggers have no track associated with them

  3. Toy Monte Carlo • Generate track at a given angle • Track crosses a strip at a random position • Generate primary ionization clusters Poisson distributed • Generate number of electrons for each cluster • Take strip with earliest time and charge over a certain threshold as the track’s coordinate Strip pitch = 0.5 mm Reconstruct track and compare slope with the generated one No transverse diffusion considered but effect is negligible for the first arriving cluster

  4. Sanity CheckDistributions of MC generated Events 10o tracks Earliest arrival 10o tracks

  5. Position and Timing Resolution as a function of incidence angle 40 deg 40 deg 30 deg 30 deg 20 deg 20 deg 10 deg 10 deg • Average spatial resolution below 0.5 mm for all angles in Small Wheel acceptance • Time of first cluster above threshold mostly below 25 nsec • Requiring, e.g, 3 out of 4 detectors to be within a BC should result in ~100% efficiency • Address of strips can be directly used in a lookup table (e.g. Content addressable memories similar to FTK

  6. Slope Resolution L= 10 cm L= 20 cm L= 25 cm

  7. Trigger/DAQ Block Diagram

  8. Block Diagram of the IC being designed To SRS For TGC there will be fewer (16 or 32) channels with LVDS outputs of individual discriminators All other features remain the same

  9. Timing Diagram Fine Time to next BC 40 MHz BC clock convenient for LHC but any clock can be used to related hit with trigger accept

  10. Small Wheel Counting Rates in kHz/cm2Radiation flux maps from GCALOR  (M.Shupe) Z1 Z2 R1 R2 Rate Z1 Z2 R1 R2 Rate 750.0 760.0 300.0 310.0 0.861459E-01 750.0 760.0 310.0 320.0 0.870514E-01 750.0 760.0 320.0 330.0 0.797542E-01 750.0 760.0 330.0 340.0 0.706889E-01 750.0 760.0 340.0 350.0 0.703702E-01 750.0 760.0 350.0 360.0 0.565054E-01 750.0 760.0 360.0 370.0 0.543138E-01 750.0 760.0 370.0 380.0 0.434476E-01 750.0 760.0 380.0 390.0 0.457534E-01 750.0 760.0 390.0 400.0 0.433348E-01 750.0 760.0 400.0 410.0 0.469865E-01 750.0 760.0 410.0 420.0 0.401987E-01 750.0 760.0 420.0 430.0 0.341343E-01 750.0 760.0 430.0 440.0 0.326369E-01 750.0 760.0 440.0 450.0 0.302566E-01 750.0 760.0 450.0 460.0 0.287393E-01 750.0 760.0 460.0 470.0 0.285842E-01 750.0 760.0 470.0 480.0 0.278045E-01 750.0 760.0 480.0 490.0 0.206697E-01 750.0 760.0 490.0 500.0 0.187729E-01 750.0 760.0 500.0 510.0 0.245147E-01 750.0 760.0 90.0 100.0 0.676965 750.0 760.0 100.0 110.0 0.531924 750.0 760.0 110.0 120.0 0.462974 750.0 760.0 120.0 130.0 0.428746 750.0 760.0 130.0 140.0 0.372947 750.0 760.0 140.0 150.0 0.353284 750.0 760.0 150.0 160.0 0.293642 750.0 760.0 160.0 170.0 0.262680 750.0 760.0 170.0 180.0 0.226831 750.0 760.0 180.0 190.0 0.188895 750.0 760.0 190.0 200.0 0.186949 750.0 760.0 200.0 210.0 0.185153 750.0 760.0 210.0 220.0 0.158295 750.0 760.0 220.0 230.0 0.134239 750.0 760.0 230.0 240.0 0.128854 750.0 760.0 240.0 250.0 0.113969 750.0 760.0 250.0 260.0 0.103517 750.0 760.0 260.0 270.0 0.102746 750.0 760.0 270.0 280.0 0.100118 750.0 760.0 280.0 290.0 0.840098E-01 750.0 760.0 290.0 300.0 0.954108E-01 EIL0 (CSC) EIL2 Trigger EIL3 EIL1

  11. Taking ONLY the first arriving hit per 64-Channel IC reduces the number of Channels used for Trigger from 2M  ~30,000, while maintaining spatial resolution <0.5 mm But are we paying a price for this? i.e. efficiency loss? Consider worst case at h= 2.4: Rate r = 10 kHz/cm2, strip length l = 50 cm, strip width w = 0.5 mm Occupancy/BC = rlwt = 6.25x10-4

  12. Can transfer 2 addresses in 1 BC • If 2 parallel paths each handling 16 chips then 4 hits can be moved in 1 BC • Is 200 MHz clock too aggressive? (long ~0.5 m connections) • Develop custom digital ASIC?

  13. GBTx (Gigabit tranceiver) Chipset, being developed at CERN • Will combine bidirectional data transfer, TTC, and DCS • 4.8 Gbps (2.56 Gbps data, 160 Mbps DCS, 640 MBps TTC), + (1.28 Gbps FEC, 160 Mbps Header) • First generation prototypes exist, a clock driver error resulted inreduced bandwidth • Production estimated by the end of 2012

  14. An Example

  15. Existing chip developed by the CDF Pisa group

  16. Time Required (BC) Muon TOF 1 Detector Response (drift time) 1 Front End Response (peaking time) 2 -- 3 Front End to GBTx 2 To USA15 (80 m fiber) 15 GBTx FPGA to CAM (up to 5 addresses per BCID) 1 – 2 CAM Read (160 MHz clock) 2 – 3 To Sector Logic 1 – 5* Total 25 – 32 * Assumes that existing sector logic clocked @ 40 MHz

  17. Summary/Work needed • Readout and Trigger concept that seems feasible • MOST of the electronics processing is for the trigger • Concept reduces the 2M channels to ~30,000 – eliminates argument that Mmegas will be much more expensive because of channel cnt. • One optical fiber per layer (GBTx assumed) • Need development of one or two digital custom Ics • Probably can piggy-back on front end development • Need extensive electronics engineering effort (U. Az already on board, Saclay is very much interested • Need extensive simulation work • Need demonstration prototype with existing CDF CAM or FPGAsasap hopefully by October test beam?

  18. Additional Slides

  19. VMM1 IC Schedule and Status Analog section: transistor-level simulations power ≈ 4 mW Charge Resolution 5k Qmax = 330 fC Pulse Response 1.2 Qin = 300 fC peaktime25ns ENC (e-) Amplitude [V] 50ns 100ns 200ns 0 0 150 time [ns] 0 0 200 CIN [pF]

  20. TTC Specs

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