Samuel Silverstein Stockholm University L1Calo upgrade discussion Overview Issues  Latency  Rates  Schedule Proposed upgrade strategy R&D

2 Upgrade phases (for this talk) Phase I (before calorimeter upgrades):  Two projects  FPGA-based MCM replacement for PPr  CMM++ in CP and JEP, options for Limited topo algorithms in CMM++ modules Topological processing in separate TP Phase II (digital calorimeter readout to USA15)  "Level 0": topological algorithms on finer-granularity "mini towers" built in RODs, plus muon objects  Fixed, low latency (< 3.2  s)  "Level 1": full calorimeter resolution, plus objects from muon and ID triggers  Longer latency, possibly asynchronous

3 SNAP12 CP 0 SNAP12 CP 2 Phase I with CMM++ (one example) 160 Mbit/s To CTP 12 To CTP 160 Mbit/s SNAP12 CP 1 SNAP12 CP 3 SNAP12 Jet 0 SNAP12 Jet Can use half of CP ROIs 1 of 2 Run faster? Quadrant border data

4 Topo Processor Jet /  E T (JEP) 0.2 x 0.2 E/   /had clusters (CP) 0.1 x 0.1 High-speed optical links Jets Clusters To CTP Energies Muons

5 Phase II concept Latency and rates  Fast L0 (40 MHz in, up to 500 kHz out, <3.2  s)  Slower L1 (500 kHz in, 9.6  s) Level 0:  Finer-granularity "mini towers" with e.g. Et, fine-location of shower maxima, longitudinal profiles, quality flags, etc.  Multi-crate L0Calo processor: sliding-window algorithms to identify features  L0Topo: trigger algorithms using calo and muon objects  L0 ROIs sent to L1Track to gather track candidates Level 1:  Refined L0 algorithms with full calorimeter data  L1Topo: trigger algorithms using calo, muon, track objects

6 Phase II concept (Murrough)

7 Latency issues Phase I:  Latency envelope 2.5  s  May currently be as few as 10 BCs from limits Phase II:  L0 trigger limited to 3.2  s (by muons)  Tile and (esp) LAr digital processing add additional latency  At least three sequential multi-Gbit links in L0 RTDP  Need to evaluate and limit all potential sources of latency

8 Latency issues Sources of additional latency:  Link choice (SerDes latency)  GBT: 8-10 BC if optimised (S. Muschter), 16 BC (GBT group)  8b/10b: 5 BC (3.2 Gbit), 3 BC (6.4 Gbit)  Upgraded firmware  CPM and JEM merger encoding (and decoding): ~ BC  CTP upgrade to 80 MHz: 2-3 BC  Topological algorithms themselves Possible latency savings  Faster FPGAs in upgraded hardware  CMM++ (Virtex E  Virtex 6)  PPr MCM upgrade from ASIC to Spartan 6

9 Rate issues Conflicting demands at sLHC  L1 tracker concept relies on high L0 trigger rate  Richard Brenner: >500 kHz  Muon detector cannot handle high L0 trigger rate  < 200 kHz No obvious options  Upgrade muon electronics  Many inaccessible boards. Years to disassemble and replace  Muon system ignores L0A, reads out after L1A  L1A latency too long. Data lost  "Private trigger" for muons?  Won't work....how do we decide which L0A will be accepted by L1? Data lost. How do we proceed?

10 Schedule issues Phase I:  CMM++ should be ready for deployment by 2015  Need to start Phase I soon  May be needed before calorimeter upgrade ( )  but discarded when calorimeters are upgraded Phase II:  Large, completely new system!  Concurrent with calorimeter upgrade ( )  Need to start Phase II soon Problem: Phase I and II development in parallel  conflicting demands on manpower, organisation, etc

11 Proposed strategy Focus on Phase II  "Staged" deployment:  L0Calo/L0Topo in time for calo upgrades timescale Fixed latency, maximum 3.2  s Run at <75 kHz until L1 is ready L0Topo compatible with CMM++ outputs –Usable as TP in Phase-1 system (see next slide)  L1 trigger ready for ID upgrade Increase L0 rate to 500 kHz Asynchronous processing?

12 Phase-II "staging" Install with calorimeter upgrades ( ) Install with ID upgrade (2020-)

13 Proposed strategy Phase-I development in parallel  Lower initial ambition level  Build and deploy CMM++ as soon as possible  Limited topo algorithms in CMM++  Muon ROIs not included?  L0Topo compatible with CMM++ outputs?  Use as TP if Phase I delayed, or too much pileup  Early, parasitic testing/integration of L0Topo before rest of L0Calo is ready?  Possible to include muon ROIs?

14 R&D results MCM replacement design is progressing well  Spartan 6 FPGA could be used to improve pileup performance, maybe lower latency. Encouraging work on CPM merger  Readout scheme makes better use of bandwidth, small cost in latency and design size  Use same format for Jets? Maybe add jet ROI energies to threshold bits New ideas for CMM++  Virtex 6 HXT adds more logic, plus up to 72 multi-Gbit transceivers (from half that on LXT device)  More optical links open new possibilities for merger topology

15 R&D results New results from GOLD  Encouraging link latency results  Experience with new HXT FPGAs  Understanding of phase II HW issues, including power, board density, etc Stockholm link test board  High-speed links can be run with TTC  Latency results compatible with GOLD 8b/10b measurements  IPG during empty LHC BCs  Similar scheme needed for any 8b/10b link. New algorithm studies  Many algorithms possible with CMM++ only  Interesting idea to combine jet and energy  transverse mass  Need to focus on questions of bandwidth (vs. processing power): how much information is needed, and where?

16 Discussion?