1. Many LAV stations in digital trigger Francesco Gonnella Photon-Veto Working Group CERN – 03/02/2015

2. LAV primitives working principles  Up to 256 lead-glass blocks  2 threshold for each block: Up to 512 channels into one TEL62 PP firmware  Seeks coincidences (~6 ns programmable) between high and low threshold  Coincidence => slewing correction, hit production  Possibility of asking a trailing on high and/or threshold crossing and a minimum ToT value to produce a hit  No coincidence => discard the hit SL Firmware  Sorts and merges hits  Merges any hits within up to 25 ns (programmable)  Outputs the L0 primitives to Gigabit Ethernet 03/02/2015Francesco Gonnella - Laboratori Nazionali di Frascati

3. The InterTEL boards  InterTEL boards are plugged on top of the TEL62 and communicate with the SL FPGA through a16-bit 40MHz bus  They were tested by Perugia (Matteo & Mattia) and are now ready 03/02/2015Francesco Gonnella - Laboratori Nazionali di Frascati

4. LAV SL firmware  Merge physical hit times from the 4 PPs  Group together hits within a given cluster (5 ns window)  Evaluate the average of the clusters, obtaining primitive times  Sort primitive times  Produce a trigger primitive  Error on primitive lost 03/02/2015 Cluster hit number Francesco Gonnella - Laboratori Nazionali di Frascati

5. Daisy-chain connection topology  Every Tel62 is connected to the next Tel62  The last Tel62 (LAV12) produces trigger primitives and sends them through its Gigabit Ethernet to L0TP 03/02/2015 TEL62 PP SL TDCB GbEth TDCB LAV2 TEL62 PP SL TDCB GbEth TDCB LAV… TEL62 PP SL TDCB GbEth TDCB LAV12 Inter-TEL bus L0TP Trigger to all TEL62s from other L0 detectors InterTEL TEL62 PP SL TDCB GbEth TDCB LAV1 InterTEL Inter-TEL bus Francesco Gonnella - Laboratori Nazionali di Frascati

6. Star connection topology  Every Tel62 is connected to an additional “concentrator” Tel62 equipped with TELDES boards instead of TDCBs  The connection InterTEL to TELDES is viable as they use the same serializer/deserializer chip. 03/02/2015 TEL62 PP SL GbEth TELDES TEL62 PP SL TDCB GbEth TDCB LAV2 TEL62 PP SL TDCB GbEth TDCB LAV… TEL62 PP SL TDCB GbEth TDCB LAV12 Inter-TEL bus L0TP Trigger to all TEL62s from other L0 detectors InterTEL TEL62 PP SL TDCB GbEth TDCB LAV1 InterTEL Francesco Gonnella - Laboratori Nazionali di Frascati

7. InterTEL connection  Where to take data from?  Where to send data to? 03/02/2015 Cluster hit number Before merging and sorting Before sending to Ethernet  Try to send it as soon as possible  Try to send as few data as possible Francesco Gonnella - Laboratori Nazionali di Frascati

8. Daisy-chain topology (1/2)  Facts:  PP and SL clock frequency: 160 MHz  InterTEL clock frequency: 40 MHz  InterTEL word length = 16 bit  Time frame duration 6.4 us i.e. 1024 clock cycles @ 160 MHz  Assumptions:  Hit rate on LAV single station: 2MHz ~12 Hit over a Time Frame 6.4 us  Cable length between two adjacent LAV stations: 15m Delay in clock cycles = (40 + (Nhit – 1) * Words * 4) * (Nlav -1) Words = 3 (40-bit absolute times require 3 16-bit words) with some effort data could be compressed 03/02/2015Francesco Gonnella - Laboratori Nazionali di Frascati

9. Daisy-chain topology (2/2)  With all the 12 LAV we obtain: 2024 clock cycle > 1024 so cannot bit done within one time frame  With 6 LAV we obtain: 920 < 1024: but a little bit at the limit  With 3 or 4 LAVs we could try to implement multiple LAV primitive generation with minimal effort Solutions:  Use less LAVs (to be done as a first step)  Add a delay and buffer data (100 us is the limit imposed by L0TP)  Send data in a smarter way (e.g. split into timestamp and fine time and send the TS only once)  Divide the 12 LAVs into 2 or 3 sub-groups and connect them to L0TP  No information about the hit-station cannot be propagated in daisy-chain topology, without major modification in firmware logic. 03/02/2015Francesco Gonnella - Laboratori Nazionali di Frascati

10. Star topology Connect many stations to one concentrator  We add an additional TEL62 board equipped with TELDES board that can receive data from all the 12 InterTEL  All the LAV can use the same firmware  We have data coming from all the LAV station all at once  Complex trigger decision can be taken  Whole new PP firmware must be written  For data receiving, modules already exist to in LKr L0 firmware  For data sending to SL, LAV firmware modules could be used  SL firmware could be the LAV one as a start and could be rewritten in order to perform complex trigger algorithm 03/02/2015Francesco Gonnella - Laboratori Nazionali di Frascati

11. Conclusions  Daisy-chain topology: CONS:  Cannot connect all LAV stations, at least with small effort  Cannot keep track of the hit station  Cannot do complex trigger algorithm PROS:  Small effort is required  Star topology: CONS:  One more TEL62 and one TELDES are needed  A serious effort is required PROS:  Could use a not-perfectly-working TEL62  Very refined triggering e.g. distinguish between muons and photons.  We could use LAV trigger since the beginning of the run in “tagging mode” 03/02/2015Francesco Gonnella - Laboratori Nazionali di Frascati

12. Thanks for your attention francesco.gonnella@lnf.infn.it 03/02/2015