LHCb Trigger & DAQ Design technology and performance. Mika Vesterinen ECFA High Luminosity LHC Experiments Workshop 8/10/2016

Transcription

1 LHCb Trigger & DAQ Design technology and performance Mika Vesterinen ECFA High Luminosity LHC Experiments Workshop 8/10/2016

2 2 Introduction The LHCb upgrade will allow 5x higher luminosity and with greatly increased trigger efficiency. Underpinned by triggerless readout and the full software trigger. And by real time methods that are being pioneered in Run-II.

3 3 Heavy flavour signatures Beauty M 5 GeV ~10 mm Charm M 2 GeV ~4 mm

4 Heavy flavour signatures Beauty M 5 GeV ~10 mm Charm M 2 GeV ~4 mm Hardware trigger thresholds * Muon pt > 2 GeV Hadron ET > 4 GeV...,... *Very approximate Run-II values. They are still evolving since the LHC hasn t yet provided the complete number of colliding bunches that we can expect during Run-II. Mika Vesterinen 4

5 5 Heavy flavour signatures Beauty M 5 GeV ~10 mm Charm M 2 GeV ~4 mm At Run-II 45 khz 1 MHz luminosity in LHCb acceptance 4 x cm -2 s -1 in LHCb acceptance Inclusive High Level Triggering ~250 exclusive selections

6 6 Run-I/II and lumi levelling Luminosity levelled at 4 x cm -2 s -1 Lint [cm -2 s -1 ] L Run-I 4 x fb -1 Run-II 4 x fb -1 LHCb

7 7 Hardware trigger bottleneck CERN-LHCC Muonic Hadronic design Run-I/II

8 8 Hardware trigger bottleneck CERN-LHCC Muonic Triggerless readout in the upgrade allows 2x higher efficiency for hadronic b decays at 5x higher luminosity Hadronic Lint design [cm -2 s -1 ] Run-I/II L Run-I-II 4 x fb -1 Run-III-IV 2 x fb -1

9 9 Run-I Trigger 40 MHz bunch crossing rate L0 Hardware Trigger : 1 MHz readout, high ET/PT signatures 450 khz h ± 400 khz µ/µµ 150 khz e/γ Software High Level Trigger Introduce tracking/pid information, find displaced tracks/vertices Offline reconstruction tuned to trigger time constraints Mix of exclusive and inclusive selections 5 khz (0.3 GB/s) to storage 2 khz Inclusive beauty 2 khz Charm 1 khz Muons Alignment and calibration

10 10 Run-I Trigger 40 MHz bunch crossing rate L0 Hardware Trigger : 1 MHz readout, high ET/PT signatures 450 khz h ± 400 khz µ/µµ 150 khz e/γ Software High Level Trigger Introduce tracking/pid information, find displaced tracks/vertices Offline reconstruction tuned to trigger time constraints Mix of exclusive and inclusive selections 5 khz (0.3 GB/s) to storage 2 khz Inclusive beauty 2 khz Charm 1 khz Muons Alignment and calibration

11 11 Run-I to Run-II 40 MHz bunch crossing rate L0 Hardware Trigger : 1 MHz readout, high ET/PT signatures 450 khz h ± 400 khz µ/µµ 150 khz e/γ Software High Level Trigger Introduce tracking/pid information, find displaced tracks/vertices Offline reconstruction tuned to trigger time constraints Mix of exclusive and inclusive selections 5 khz (0.3 GB/s) to storage 2 khz Inclusive beauty 2 khz Charm 1 khz Muons Alignment and calibration

12 12 Run-I to Run-II 40 MHz bunch crossing rate L0 Hardware Trigger : 1 MHz readout, high ET/PT signatures Real time 450 khz h ± 400 khz µ/µµ 150 khz e/γ Sub detectors fully aligned and calibrated in real time Software High Level Trigger HLT performs offline quality Introduce tracking/pid information, find displaced tracks/vertices Offline reconstruction tuned to trigger time constraints Mix of exclusive and inclusive selections reconstruction, incl. RICH PID. 5 khz (0.3 GB/s) to storage 2 khz Inclusive beauty 2 khz Charm 1 khz Muons Alignment and calibration

13 13 Run-I to Run-II 40 MHz bunch crossing rate L0 Hardware Trigger : 1 MHz readout, high ET/PT signatures Real time 450 khz h ± 400 khz µ/µµ 150 khz e/γ Sub detectors fully aligned and calibrated in real time Software High Level Trigger HLT performs offline quality Introduce tracking/pid information, find displaced tracks/vertices Offline reconstruction tuned to trigger time constraints Mix of exclusive and inclusive selections reconstruction, incl. RICH PID. 5 khz (0.3 GB/s) to storage Real time physics analysis 2 khz Inclusive beauty 2 khz Charm 1 khz Muons with the Turbo stream Comp. Phys. Com. 208, 35-42, (2016) Alignment and calibration

14 14 Run-I to Run-II 40 MHz bunch crossing rate L0 Hardware Trigger : 1 MHz readout, high ET/PT signatures 450 khz h ± 400 khz µ/µµ 150 khz e/γ Software High Level Trigger Introduce tracking/pid information, find displaced tracks/vertices Offline reconstruction tuned to trigger time constraints Mix of exclusive and inclusive selections 5 khz (0.3 GB/s) to storage 2 khz Inclusive beauty 2 khz Charm 1 khz Muons The fully deferred split HLT allows us to Alignment and calibration employ the HLT farm throughout the year

15 15 Run-II to Upgrade

16 16 Run-II to Upgrade

17 Triggerless readout Data network throughput [ Tbit / sec ] Figure courtesy of Niko Neufeld, based on presentations at DAQ@LHC 2016 Mika Vesterinen 17

18 18 LHCb upgrade DAQ Cavern Surface data center

19 19 Full software trigger

20 Track reconstruction Scintillating Fibre Tracker VELO Upstream Tracker LHCb Tracker Upgrade TDR, LHCB-TDR-015 Mika Vesterinen 20

21 Track reconstruction Scintillating Fibre Tracker VELO Upstream Tracker LHCb Tracker Upgrade TDR, LHCB-TDR-015 Mika Vesterinen 21

22 Physics performance The 30 MHz tracking sequence only compromises a few % in efficiency compared to the ideal version. LHCb Trigger and Online Upgrade TDR LHCB-TDR-016 Mika Vesterinen 22

23 Speed Reconstruction time for nominal LHCb upgrade conditions measured on a node 1 from the current LHCb EFF Algorithm Time [ms] VELO tracking 2.0 VELO-UT tracking 1.3 Forward tracking 1.9 Primary vertexing 0.4 Total 5.4 LHCB-TDR-016 Within estimated budget 2 of 13 ms, allowing for subsequent selection and reconstruction 1. Dual socket x86 server with Intel x physical cores + 12 hyper threads, and 24 GB RAM. 2. Based on CPU growth projections Mika Vesterinen 23

24 Speed Reconstruction time for nominal LHCb upgrade conditions measured on a node 1 from the current LHCb EFF Algorithm Time [ms] VELO tracking 2.0 VELO-UT tracking 1.3 Forward tracking 1.9 Primary vertexing 0.4 Total 5.4 LHCB-TDR-016 Ongoing effort to (i) adapt LHCb software to better exploit modern CPU architectures & (ii) evaluate use of co-processor technologies. Mika Vesterinen 24

25 25 How much signal do we need to record?

26 26 Anatomy of upgrade events LHCb-PUB Beauty Charm τ > 0.2 ps Hyperons

27 Anatomy of upgrade events The goal of the trigger is no longer to distinguish signal from background, but rather to distinguish different signals. Mika Vesterinen 27

28 Selectivity example 60M Right sign decays Candidates / (0.1 MeV/c 2 ) LHCb (a) D +! D D +! D 0 + Data Fit Background M (D 0 π s + ) [GeV/c 2 ] Candidates / (0.1 MeV/c 2 ) LHCb 50 (b) k Wrong sign decays Data Fit Background M (D 0 π s + ) [GeV/c 2 ] Figures correspond to full Run-II dataset PRL 111, , 2013 Mika Vesterinen 28

29 29 HLT output rate Beauty Charm Muons Other Run-II Approximate HLT output rate in khz

30 30 HLT output rate Beauty Charm Muons Other Run-II un-iii* Run-III Approximate HLT output rate in khz

31 31 HLT output rate Beauty Charm Muons Other Run-II un-iii* x5 luminosity Run-III Approximate HLT output rate in khz

32 32 HLT output rate Beauty Charm Muons Other Run-II un-iii* Run-III x5 luminosity No hardware trigger bottleneck Approximate HLT output rate in khz

33 HLT output rate Beauty Charm Muons Other Run-II un-iii* Run-III x5 luminosity No hardware trigger bottleneck Approximate HLT output rate in khz E.g., Triggerless readout provides great potential for kaon physics 1,2,3 1. LHCb-PUB LHCb-PUB KAON 2016 indigo link Mika Vesterinen 33

34 34 HLT output rate Beauty Charm Muons Other Run-II un-iii* Run-III Approximate HLT output rate in khz Real time physics analysis methods needed to manage these data

35 35 HLT output rate Beauty Charm Muons Other khz isn t the appropriate unit... Run-II un-iii* Run-III Approximate HLT output rate in khz Real time physics analysis methods needed to manage these data

36 36 The Turbo Stream Comp. Phys. Com. 208, 35-42, (2016) Run-II HLT already performs full offline reconstruction Charm analysis is mostly based on the signal candidate We can do real time physics analysis which discards the majority of the event. Stream Full Turbo Event size 70 kb 5 kb

37 37 The Turbo Stream JHEP10 (2015) 172 Comp. Phys. Com. 208, 35-42, (2016) 2015: 13 TeV J/ψ μμ cross section measurement presented within 1 week of recording the data! 2016: More than 200 Turbo HLT2 lines in operation.

38 Evolution of Turbo Example: What if, unlike the D-D mixing example, you want all of the favoured charm decays, and not just the candidate? E.g. D*X spectroscopy Mika Vesterinen 38

39 39 Evolution of Turbo Turbo in 2015 Appropriate for analyses with exclusively triggered candidate

40 40 Evolution of Turbo Turbo in 2015 Turbo in 2016 Appropriate for analyses with exclusively triggered candidate Applicable to most physics analyses

41 Evolution of Turbo Turbo in 2015 Turbo in 2016 Appropriate for analyses with exclusively triggered candidate Applicable to most physics analyses We approach the flexibility to perform any type of physics analysis in real time with the Turbo stream! Mika Vesterinen 41

42 42 Beyond 2 x cm -2 s -1? Proposed phase II LHCb upgrade in LS4 Record 300 fb -1 at 2 x cm -2 s -1 See Chris Parkes talk in this workshop (link).

43 43 Trigger considerations We wouldn t go back to a triggered readout. - Increased occupancy and #channels should easily be absorbed by a larger #links and technology evolution. The main constraint is likely to be offline computing. The real time approach will be key.

44 Summary The LHCb upgrade requires a revolutionary advance in trigger and DAQ which is needed to better exploit the LHC potential for HF physics. Good progress towards the triggerless readout and the full software trigger Real time methods are being proven in Run-II. Bold but realistic plans are taking shape for future upgrades. Mika Vesterinen 44

45 45 Backup slides

46 46 Anatomy of upgrade events

47 Output bandwidth LHCB-TDR-016 Consider 2, 5 and 10 GB/sec scenarios assuming 120 kb raw event size Mika Vesterinen 47

48 LHCB-TDR-016 Mika Vesterinen 48

49 49 HLT output rate More than 1 billion charm signal D 0 D+ Ds Approximate HLT output rate in khz D * Λc