Preshower Front-End Boards News LHCb group / LPC Clermont  News  TRIG-PGA Bit Flip Behaviour  Bit Flip Simulations  Conclusion

2 First Final Prototypes FE Boards received from Hitachi Fully LPC Test Bench = FUNCTIONNAL Production tests processes ready FEPGAs data processing path offsets Analogic and the DAQ parts by analogic injection with AWG and DAQ through the SEQPGA Power-up failure SEQ ?, ‘random’ Problematic with multiple Boards ‘sine’ injection with AWG Stable Offsets over 55 h 1. PS FEB Validation : Data Path

Functioning of the delay chips & Synchronisation ~OK, ongoing studies Connectivity on the trigger path: OK FEPGA-TRIGPGA inputs/outputs with memory boards Trigger algorithm: OK see also Combined Tests in Building 156 Manufacturer JTAG Tests for Production Basic tests on wires between PGAs, spot soldering defects Improved JTAG tests including most of the board I/Os with dedicated back-plane data conversion, access to individual 40 MHz, TTL levels internal buses, pga pins + links drivers and connectors Limitation : no JTAG access to analogue parts and ADCs 1. PS FEB Validation : Trigger Path

1. TRIG-PGA ISSUE We are in touch with ACTEL France No obvious problem from PGA code, implantation Internal to APA450, Noise handling issues suggested ? An issue was spotted with the APA450 TRIG-PGA Some input patterns lead to erroneous output Failure diagnostic : output values missing, then repeated TRIG-PGA enters a ‘Blocked’ status This failure can be correlated to inputs Bit Flip Rate ( BFR ) Meanwhile … … TRIG behaviour extensivelly LPC, Clermont Test Bench …

2. Bit Flip Generation Total Available BitsUsed with RAMsUsed with Memory Boards PS64 0 SPD64 ECAL2610* Neighbours34 0 Total188 ( 100 % )178 ( 95 % )74 ( 39 % ) Table 1: Bit usage for the TRIG bit flip tests. In the last raw are also indicated the fraction of the total 188 bits varied during the tests. (*) The BCID counters of ECAL bits have a particular status. Bit Flip Rate ( % )Maximal Run Duration ( cycles ) RAMs: PS & SPD random ∙10 6 Memory Boards: SPD random ∙10 8 SPD alternated & full flip ∙10 5 Table 2: Bit Flip Rate generation strategies. For the RAMs setup all data, except BCIDs were taken randomly at each cycle. In MB runs in order to finely investigate the problematic area of high BFR we used a combination of some bits being fully flipped while others were alternated with random patterns. 40 s 40 MHz = 2 days of injection 8 words of 8 bits Mask n/8 Monte-Carlo strategy to study BFR impact 2 Internal BCID counters [0; 255 ] Average BFR = 2 % BFR = flips / 188

2. TRIG-PGA Failure Distribution Figure 1: TRIG PGA failure in the RAM configuration for a mean BFR of ~47 %. The figure shows the distribution of cumulated flips in PS and SPD bits before failure occurs. The open circles stand for board P#8-01 and the plain dots for board P#8-02. Error bars are statistical. Statistical spread: Fluctuations in the BFR over time due to BCIDs, pattern randomization protocol Inherent. Even for same inputs few % spread Failure occurs on average when cumulating some amount of Bit Flip Board P#8-02 Board P#8-01

2. TRIG-PGA Failure as BFR There is a threshold BFR, f r,0, below which no failure occurs. Failure is not driven by a dynamical process. Below the threshold, the TRIG-PGA can re-generate. Postponed failure sequency Blocked fr,0 Additional cycles before failure Relax Relax BFR = 5 % Relax BFR = 16 %

2. TRIG-PGA Failure as T, Clock f Figure 4: TRIG PGA failure in the MB configuration for various temperatures and operating clock frequencies. On the left is shown the failure cycle number for different temperatures. The usual conditions encountered in the lab were of 30 ºC. The right figure shows the failure cycle number for various operating frequencies. The nominal frequency is 40 MHz. Below 25 MHz no failure occurs up to a maximal 39 % BFR. Failure depends on Temperature, Clock frequency No -55 ºC No failure below 25 MHz

2. TRIG-PGA Recovery Once blocked the TRIG-PGA can recover if BFR below threshold Full recovery is long … ~ 10 3 cycles Blocked 1 st load 2 nd load Relax Recovery Sequency ‘Exhausted’ plateau Full recovery Recovery litle depends on load and relax BFR values ( except threshold )  Suggests time driven mechanism

2. TRIG-PGA Failure Cost Model Failure cycle follows a simple ‘Cost’ model as BFR Assume cost is stationnary Blocked Cross-check sequency Fully random BFR in perfect agreement with data Cost modeled from data Cross-check model ~ 20 % bias when BFR varies in time ; BOOT ? Cost / cycle ( % )

3. TRIG-PGA Bit Flip Expected in LHCb Figure 9: Bit Flip Rate distribution for pp events at a luminosity of 5·10 32 cm -2 ·s -1 and for the two ‘hottest’ cells ( 82, 91 ) of the PS/SPD system. The SPD threshold was set as low as 0.3 MIP. Mean Bit Flip Rate ( % ) Contribution to BFR ( % ) BCIDs2.131 PS bits0.914 SPD bits2.029 ECAL addresses Total Table 3: Mean Bit Flip Rate for cells ( 82, 91 ) at a luminosity of 5·10 32 cm -2 ·s -1. The fractions at which the various bits contribute to the BFR are also indicated. Bit Flip simulated from DC 06 minimum bias pp events (10 3 events / cell) Set SPD threshold to 0.3 MIP = very low Select the 2 ‘hottest’ boards (close beam line) L = 5·10 32 cm -2 ·s -1 Average BFR well below failure Threshold But … Distribution extends well above ( ~ 3 % above ) Threshold BCID Counters

3. TRIG-PGA Failure LHCb Figure 10: Cost probabilities and TRIG-PGA failure as simulated. The left figure shows the maximal cost distribution within 65 k events runs. The right figure is the failure probability within 1 year of LHC operation and assuming various cost thresholds. MiniBias pattern injection 40 MHz over 1 day : No TRIG-PGA failure But always same pattern … 40 s LHC = 2 days tests Estimate failure from simulation / Cost model MHz simulated in Lyon batch farm 1 st : Bunchs of 65 k cycles  No faillure predicted 2 nd : Extrapolate to 1 yr LHCb ‘non-stop’ Cost Below 10 % Failure cost ~ 80 % SHOULD NOT HAPPEN in standard conditions

4. CONCLUSION THE PS FEB ARE WORKING PROPERLY fits our needs PS FEB BOARDS EXTENSIVELY LPC & ongoing in Building 156 Power-up SEQ ? TRIG-PGA ‘pathologic behaviour’ No problem expected in standard LHCb conditions Actel LPC Monday, December 4 th  Production Should Follow