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LAV contribution to the NA62 trigger

LAV contribution to the NA62 trigger. Mauro Raggi, LNF ONLINE WG CERN 9/2/2011. LAV can help rejecting photons from p + p 0 decay and m LAV can provide Time ( Dt 500ps), Energy (20%), f position The LAV detector is able to provide all its information directly @ L0TP

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LAV contribution to the NA62 trigger

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  1. LAV contribution to the NA62 trigger Mauro Raggi, LNF ONLINE WG CERN 9/2/2011

  2. LAV can help rejecting photons from p+p0 decay and m LAV can provide Time (Dt 500ps), Energy (20%), f position The LAV detector is able to provide all its information directly @ L0TP The LAV it’s able to send all it’s data to L1 PCs following L0TP request We have the possibility to choose in which trigger level we use the LAV information LAV in the L0 or L1 trigger?

  3. Why the LAV in LVL0?

  4. Identify MIPs (μ or π) and to distinguish them from photons and electrons: • N blocks per ring ≤ 2 for each involved ring • 3 ≤ N firingblocks≤ 6 • E_bl< 200 MeVforeach block over threshold • E_ring(i) /E_ring(i+1) < 2 foreach pair of rings • N_cl= 1, one cluster (only) in the LAV station • The LAV MIP trigger canbematchedwith a MUV hit todistinguish pions frommuons LAV MIP primitives to L0

  5. MIP single block efficiency of the LAV is >95% at the foreseen thr 7mV We will have >3 blocks per MIP in each LAV so the efficiency will rise well above 99% Can LAV12 be used, in absence of the CHOD, to compensate the geometrical inefficiency of MUV in covering the RICH triggered muons? L0 algorithm efficiency to be studied! LAV MIP efficiency test beam

  6. Not necessary very efficient for very low energy particles @ L0? • All conditions can be used in or or and • Ntot> 10 OR Etot > 1 GeV • Ering> 0.1 GeVx Nringfor al least 2 rings • E_ring(i) /E_ring(i+1)> 2 forat least a pair of rings • The real algorithmwillbetunedusing the LAV MC for L0 • Purityfor low energy photon is an issue EM showers trigger

  7. Not trivial to distinguish low energy photons form muons Muon 1 GeV Electron 1 GeV P. Massarottiform LAV MC MC multiplicity MIP showers

  8. ANTI-A12 • STEP I: only ANTI-A12 in L0: • Compute only ANTI-12 primitives and send to L0TP • Receive the L0TP response and send all hits to L1 PCs • Reconstruct the whole detector information in PCs Producing the L0 LAV STEP I

  9. Advantages of having only ANTI-A12 in the L0 • Only needs firmware development • The algorithm only involves 1 ANTI • Don’t require TEL62 communication & LAV data condensation • Save a lot of man power (good for the synchronization or early run) • Disadvantages • Lose ~ 50% of LAV rejection capability in L0 • Lose some muon discrimination capability • All the rejection is recovered in L1 Producing the L0 LAV STEP I

  10. Producing the L0 LAV STEP II

  11. Scenario n 2 all the 12 LAV directly in LvL0 (as in the TDR) • Compute local primitives into single ANTI and send to concentrator • Condensate all the 12 station’s primitives into a LAV primitive • Send the LAV primitive to L0TP and receive the response • Distribute the L0TP response to all the LAV’s TEL62 • All the TEL62 send the data to L1 PC’s using remaining eth interface • Advantages • Full LAV rejection capability @L0 (50% better rejection p+p0) • No need of having the LAV in the L1 trigger (only integrity checks) • Disadvantages • Need to project and build 4Gbit Eth receiver for TEL62 mezzanine • Can a commercial 24x1Gbit Eth switch be enough? • Need 1 more dedicated TEL62 • Need to develop a dedicated firmware for the concentrator TEL62 What we need for step II

  12. LAV is able to send all it’s raw hits to LvL1 • Care should be taken to noisy channels • The LAV can produce 2 primitives @ L0 • MIP primitive (p or m) order 99% efficiency • Shower primitive (e or g) low E purity to be understood • LAV can have 2 approach to trigger • Participate to L0 with only ANTI-A12 50% rejection • Exploit the rest of the rejection at L1 • Use the full detector directly at L0 (all 12 stations) • The data load seems feasible • The computing required in the TEL62 has to be understood Conclusions

  13. NA62 trigger rates overview At which level is the LAV system able to send data? How many data will it send?

  14. From TDR LAV expected raw rates TDR Using an hit size of 192 bits and only 7 hits per event (MIP) In principle the TEL62 is able to transmit all the hits of the LAV using 3 Gbit eth interface leaving 1 free for the trigger.

  15. What is already done from Spasimir it’s more or less all • Assume that the LAV is efficient for all the impinging photons is a good approximation @ trigger level • The only upgrade could be to implement a thr at 50 MeV below which the detector is inefficient • Try to understand the L0 LAV algorithm efficiency for low energy gamma. Simulation of LAV rejection factors

  16. LAV maximum data volume revised Raw LAV rate computed assuming: 15 hits/station and 160bits per hit (included extra hits in the TDC)Due to the fact that the rate is MIP dominated we have more than a factor 2 safety factor (expected hits per MIP ~7 hits/station) * Assumes the station has data to send to LVL1 for each LVL0 request (pessimistic) ** Assumes 50% of the stations will respond to each LVL0 request (pessimistic) LAV system should be able to send all its data, without any reduction, to LvL1 following a LvL0 request!

  17. Each hit will produce 4 of this word • 2x32bit leading + 2x32bit trailing • Assuming to add a 32 bits time stamp to the hit • Total hit size is 160bits Hit size

  18. Assuming the highest rate ANTI-A1 1.77MHz • Assuming a factor 2 more hit 15/stat (refirings) • Total size of data produced by a single ANTI: • 15hits*160bit*2MHz = 4.8 Gbit/s • 600 Mbyte/s into TEL62 memories • TEL62 has 2Gbyte or 4Gbyte DDR memories • 2Gbyte means ~ 3.3 s ANTI data • 4Gbyte means ~ 6.6 s ANTI data Maximum latency in TEL62 DDR

  19. The concentrator will receive the primitives from the LAV stations with following information • Trig. type (muon or gamma) • Event time (Fine time + time stamp) 40 bits • Event Energy (most probably charge) • Event position (phi position of the seed in the LAV station) Data load to the concentrator Ev. type Ev. Energy Ev. Position • Assuming as rate the LAV total rate of 11MHz and data size 64bit • Total data load to concentrator= 11MHz*64bit = 704 Mbit/s • The rate divided over 12Gbit eth can be managed by 1 TEL62

  20. The concentrator task is to condensate the 12 station information in a single primitive message to L0TP The concentrator should reduce the total LAV rate 11MHz to the LAV OR rate of 4.5 MHz Data load from concentrator to L0TP For each local primitive the concentrator should send 2x32bit word to L0TP shown above: Data to L0TP=2x32x4.5E6 = 288 Mbit/s = 36MByte/s using the LAV OR rate 4.5MHzData to L0TP=2x32x11.5E6= 740 Mbit/s = 93MByte/s using the LAV tot rate 11.5MHz

  21. Reduce the number of extra hits • Define in the FPGA an algorithm which suppress extra hit in the same TDC channel • Reduce the size of the hit information • Transmit only hit charge and time. • Condensate the LAV information • Provide particle based info instead of hits Reducing the data volume @ LVL1

  22. HPTDC produces 4x32 bits word per hit • 2x32bit leading and 2x32bit trailing edge • 32bit time stamp • 160bit per hit • If compute a time and charge in the TEL62 or @ L1 • 1x12 bit charge + 1x8bit fine time + 12 bit channel • 1x32 bit time stamp • 64 bit per hit • Can gain more than a factor of 2 in hit size! Transmit only charge and time

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