Alternatives for TileCal digital readout to FEX

1. Alternatives for TileCal digital readout to FEX Samuel Silverstein, Stockholm University

2. Background • Phase-1 eFEX and jFEX receive digital EM layer data from LAr DPS • But equivalent Tile data path not available before Phase 2 • So: need to extract digital hadronic tower sums produced from the current analog sums sent to L1Calo • Three points where this can be done • See next slide

3. Alternatives Barrel sector logic Muon Trigger MuCTPi • Can extract Tile tower sums from: • Tile receiver stations • PreProcessor modules • JEM modules in JEP Endcap sector logic Muon detector eFEX Central Trigger L1Topo CTP DPS EM calorimeter digital readout C O R E EM data to FEX jFEX Hadronic data to FEX Tile tower “DPS” 3 2 1 JEP PreProcessor C M X Analog sums from Tile/LAr Receiver stations JEM nMCM CP New/upgraded Hardware C M X CTP output L1Calo Trigger Topological info

4. Considerations • Latency • Dynamic range • Current L1Calo towers have 8 bit dynamic range with 1GeV/LSB • Would like 9 or 10 bits, if possible • Cost to implement • Risk of disruption to existing system

5. Option 1: Tile Rx stations • Signals extracted at arrival point in USA15, so latency cost is minimal • Must build a new system to digitize and process analog signals • No constraints on dynamic range • Cost is high – essentially need to build new receiver and PreProcessor systems • High risk of disruption to current L1Calo: • Analog data path ahead of L1Calo rearranged • Where do we fit the new systems that do this?

6. Option 2: PreProcessor • New MCM (Phase 0) • FPGA based tower processing • Can drive higher-speed data to the LVDS link driver card(blue arrows) • Replacement link card (Phase 1) • Send tower data electrically to CP and JEP (same as now) • An FPGA and parallel-optic transmitter (e.g. minipod) produce hadronic output to FEX • Fiber ribbon takes data from link card to an MTP/MPO output port (probably on front panel) nMCM prototype

7. Option 2: PreProcessor • Minimal latency: • Essentially equal to option 1; • Can extend dynamic range: • nMCM can drive outputs at higher rates, so more bits per tower possible • ‘Easy’ to get 9 bits, 10 bits probably possible • Relatively low cost • nMCM will already exist • A few (small) LVDS link boards • Possibly need to replace some PreProcessor mother boards (8 layers, low component count) • Low disruption: Only upgrading existing boards

8. Option 3: JEM Upgrade Upgraded input cards Double-ratetower data from upgraded PPM(960 Mbit/s) High-speed links to FEXfrom input cards to front panel (lowest latency) (hadronic tower sums)

9. Option 3: JEM upgrade • Higher latency: • Serial transmission from PPr to JEP adds multiple BCs to latency • Limited dynamic range: • BCMUX protocol consumes some bandwidth • 9 bits possible (by removing parity), 10 bits probably not possible • Similar cost to Option 2 • PreProcessornMCM and link cards still get replaced (but not PPr mother boards?) • Plans to upgrade JEM daughter boards anyway • Low disruption: Again, similar to Option 2

10. L1Calo does not favor option 1 • Significant risk of disrupting the current analog data path to L1Calo • The proposed new system would have essentially the same functinality as the existing L1Calo PreProcessor • And where does it all fit? • No latency advantage over the PreProcessor • And highest cost

11. Option 2 favored over 3 • Lower latency • Fewer boards in the hardware chain • Everything on the PreProcessor • Easier to expand/change dynamic range • When would we use option 3? • Only if we can’t get optical data out of the PreProcessor directly. • Options being considered…no show-stoppers seen yet