1. Level-1 Trigger CMS Week, Brussels 14 Sep. 2011 C.-E. Wulz Deputy Trigger Project Manager Institute of High Energy Physics, Vienna Prepared with slides/material from: L. Guiducci, M. Jeitler, P. Klabbers, M. Konecki, A. Kropivnitskaya, E. Perez, A. Tapper

2. CMS Week, Sep. 2011C.-E. Wulz Trigger menu development  currently running with “3e33 menu” −menu designed for instantaneous luminosity of 3×10 33 cm -2 s -1 −small updates applied last week  one more menu planned for 2011 proton run 1

3. CMS Week, Sep. 2011C.-E. Wulz Recent L1 trigger developments  new muon combination scheme proposed in GMT −instead of taking minimum P T of two systems take the one with the higher rank −will lead to a few percent better efficiency −influence on rates has to be tested −new LUTs and configuration key made −currently being analyzed  new CSC P T assignment −based on CLCT in ME1  new features in RPC PACT −changed algorithm, to increase efficiency −HSCP trigger: 2 BX wide and 1 BX delayed wrt DT and CSC 2

4. CMS Week, Sep. 2011C.-E. Wulz Golden eta region: 1.2 < η < 2.1 2 or 3 station tracks with ME1 Improved ME1 CLCT patterns for 2 station tracks: - curves P T ≥ 5 GeV the same for PTLUT2010 and PTLUT2011 as expected; CLCT pattern starts to work from P T > 5 GeV - Efficiency below threshold drops from 5-10% (2010) to ~2% (2011) for P T thresholds ≥ 7 GeV and up - Significant improvement in 2011 compared to the 2010 P T assignment, especially for P T ≥ 7 GeV, lowering the trigger rate CSCTF P T assignment 3

5. CMS Week, Sep. 2011C.-E. Wulz I n 2011 the RPC PAC trigger algorithm was changed: in the barrel it requires at least 3 layers fired (out of 6 available) to generate a muon candidate. 4 layers were required in 2010. It was possible since the chamber noise is lower than expected.  efficiency in the barrel increased The optical links were arranged to obtain better geometrical coverage in the region between wheels 0 and +/- 1  additional increase of the efficiency in |  | ~0.3 Offline muon p T > 8GeV/c Offline muon p T > 8GeV/c Offline muon p T > 7GeV/c Offline muon p T > 7GeV/c The PAC is now able to trigger on “slow” particles, which reach the muon system in the next BX: it looks for the coincidence of hits in two consecutive BXs, the candidate BX is determined by the BPTX trigger veto. L1 RPC Trigger Efficiency including detector geometrical acceptance and hit efficiency vs L1 CSC or DT trigger RPC PAC trigger improvements in 2011 4 CMS Week, Sep. 2011

6. C.-E. Wulz Stability of L1RPC after automatic HV versus pressure correction Variation of chamber efficiency affects the absolute trigger efficiency (difficult to follow) and p T spectrum check fraction of L1RPC candidates with given p T Code vs all. after applied modifications RPC trigger p T spectrum stable vs pressure stability better in barrel than in endcaps HV(p) corrections no corrections from pressure changes at the beginning of each fill 5

7. CMS Week, Sep. 2011C.-E. Wulz RPC data synchronisation Only small modification of timing settings done in 2011 6

8. CMS Week, Sep. 2011C.-E. Wulz Recent L1 trigger developments (continued)  new jet energy corrections have been developed −had only been applied up to 92 GeV −1-hour test run with new corrections has been taken −modifications to be applied for next menu (“2011, version 7”) 7

9. CMS Week, Sep. 2011C.-E. Wulz L1 jet energy calibration 2011 SO FAR CORRECTED 2011 DATA UNCORRECTED 2011 DATA Uncorr In 2010 running no jet energy corrections Jet energy corrections were derived from Monte Carlo for 2011 and tested with data (Brown University) Corrections tested up to 130 GeV (saturation value in 2010) For higher luminosity need to extend corrections up to higher P T ΔR<0.5 match between L1 and RECO jets 8

10. CMS Week, Sep. 2011C.-E. Wulz L1 jet energy calibration 9 New jet energy corrections derived from Monte Carlo using JetMET code Tests on existing data and Monte Carlo Extends high-P T region and improves low-P T region a little Test run taken and validated ➔ ready for physics NEW CORRECTIONS 2011 DATA New corrections Old corrections Monte Carlo ±10%

11. CMS Week, Sep. 2011C.-E. Wulz Recent L1 trigger developments (continued)  New beam gas triggers −triggers based on BSC not useable at current high luminosity  Present beam gas trigger based on HF, uses unpaired bunches  suffers from strong “albedo” after trains of colliding bunches −background from delayed nuclear reactions  New triggers use special BPTX signal after “quiet” period without collisions −500 ns, “post-quiet unpaired BPTX signal” −thanks to BRM group for supplying this signal 10

12. CMS Week, Sep. 2011C.-E. Wulz “post-quiet unpaired bunches” beam 1 11

13. CMS Week, Sep. 2011C.-E. Wulz Recent L1 trigger developments (continued)  new ideas for luminosity measurement −needed because of pileup effects distorting zero-counting method −proposed by Marco Zanetti and Nicola Bachetta  based on Pixel cluster counting  requires zero-bias trigger that is only active for a few bunch crossings in orbit −so that within rate budget (1 kHz at L1) each bunch crossing gets reasonable statistics within a lumi section (23 seconds) −luminosity depends strongly on bunch crossing −Global Trigger firmware update allows to select individual bunch crossings for a trigger algorithm 12

14. CMS Week, Sep. 2011C.-E. Wulz L1 trigger rate capability  rate limits at Level 1 have been rechecked with real data −by applying progressively lower prescales to L1_SingleEG5  CMS runs up to design value of 100 kHz without significant deadtime −deadtime problems sometimes observed were caused by beam conditions (PKAM events in Pixels) and not by high rate 13

15. CMS Week, Sep. 2011C.-E. Wulz - Cross-sections of selected (*) L1 triggers vs instantaneous luminosity - WBM fit is used to compute the “expected” cross-section - (*) single object triggers, with the lowest P T /E T cut which is unprescaled in all prescale columns of the menu L1 trigger cross section monitoring 14

16. CMS Week, Sep. 2011C.-E. Wulz - Measured/Expected cross-section vs lumi section number for certification - Currently used by shifters to fill Run Registry - Goal is to generate GOOD/BAD LS ranges automatically L1 trigger cross section monitoring 15

17. CMS Week, Sep. 2011C.-E. Wulz 3e33 (EG20) 3e33 (EG20) 2e33 (EG15) 2e33 (EG15) 1.4e33 (EG12) 1.4e33 (EG12) ~July ~August - Jumps due to the different selection of monitored trigger object - Can check stability of the triggers P. Musella, J. Pela 16 Trigger cross section history

18. CMS Week, Sep. 2011C.-E. Wulz Prediction based on 3e33 data (PU increase not included) Predictions for 5e33 based on the 3e33 data 17 Data from run 175921 (3e33) used to emulate the “5e33 column” of the current menu : lead to 80 kHz + 10% (PU from 3e33 to 5e33) = about 90 kHz Current plan for the 5e33 menu : - quite similar to the “5e33 column” that we are running currently : unprescaled: EG20, SingleMu16_Eta2p1, SingleJet128 - A new L1 menu will be deployed though, with : - L1_DoubleEG_15_5 (7 kHz) taking over from DoubleEG_12_5 - brings the expected rate to 75 kHz + 10% PU = 82 kHz - L1_Muxx_MuOpen - to be defined - SingleMu10_ETM20 (tiny rate) - DoubleJet36_Central prescaled by only 5 - will add ~ 3 kHz i.e. expect ~ 85 kHz which should be sustainable. Note that the rate in cross-triggers starts to be large.

19. CMS Week, Sep. 2011C.-E. Wulz Effect of Pile-Up on L1 rates : trigger x-sections in latest runs TripleJet_36_36_12 Xsection increased by 40% between 2e33 and 3e33 Example seeds (mostly unprescaled at 3e33) that are most sensitive to PU : EG18_ForJet16 Increase x 2 QuadJet20_Central +75% TripleEG_8_5_5 +20 % ETM_30 + 30% (finally p’ed a bit) 18 CMS Week, Sep. 2011C.-E. Wulz

20. CMS Week, Sep. 2011C.-E. Wulz SingleMu14_Eta2p1 19 Most seeds, especially the widely used higher thresholds seeds, behave better : SingleEG15 + 4 % SingleJet92 + 5% Roughly : Seeds that are sensitive to PU account for 25 - 30% of the rate. C.-E. Wulz Effect of Pile-Up on L1 rates : trigger x-sections in latest runs

21. CMS Week, Sep. 2011C.-E. Wulz The L1 menu (L1Menu_Collisions2011_v5) deployed for the 3e33 menu 20 Measured rates (kHz) at 3e33 Prediction of rates and first definition of prescales based on earlier data ( ~ 1e33) : emulation of the total L1 rate for a given scenario at 3e33 was obtained from the earlier data, using the L1Accept stream (“nanoDST”, ~ 5 kHz of L1A events, with only the L1 information) neglecting the PU effect: total predicted rate at 3e33 was ~ 73 kHz. estimated PU effect from 1e33 to 3e33 : increase the total L1 rate by 10-15%. i.e. we were expecting a total rate of 80 kHz. Rates actually measured at 3e33: 80 kHz in run 176163 (Sept 12) at 2.9e33. i.e. the predictions were in the right ballpark see breakdown in the plot biggest are EG15 (16 kHz) SingleMu16 (13 kHz) DoubleJet44 (12 kHz)

22. CMS Week, Sep. 2011C.-E. Wulz PU effect on total L1 rate in recent runs 21 Compare rates of two runs taken with prescale index = 2 : run 176201, LS 135 – 145, lumi = 3e33 - correct for the deadtime of ~ 10% : L1A = 84 Hz run 175921, LS 400 – 420, lumi = 2.2e33 - correct for the fact that TripleJet seed was still unprescaled in that run, while it is prescaled in 176201 : L1A = 57 Hz PU effect on the total L1 rate, from 2.2e33 to 3e33 : + 8 %. Assuming a similar slope between 3e33 and 5e33 : - the PU would increase the L1 rate by about 10%. (Things are likely to be a bit worse though, because cross-trigger seeds (low PT objects, hence PU sensitivity) contribute more to the total rate at 5e33.)

23. CMS Week, Sep. 2011C.-E. Wulz - Study per P T cut between 10-20 GeV/c with data from 1-2e32 running - Preparation of the 5e33 menu - Turn-on positions and slopes are OK 22 Muon trigger P T cuts: turn-on curves

24. CMS Week, Sep. 2011C.-E. Wulz L=5E33 |eta|<2.4 |eta|<2.1 |eta|<2.4 |eta|<2.1 - Rate measured using NanoDST data, projected to 5E33 luminosity - >70% of total rate from |eta|>2.1 - Higher P T cuts less and less effective at high  - Introduced  cut at 2.1 - Keep lower L1 thresholds - Some gain in plateau efficiency L1 Eta cut 23 CMS Week, Sep. 2011C.-E. Wulz Muon trigger P T cuts: rates

25. CMS Week, Sep. 2011C.-E. Wulz Threshold101214161820 Eff loss for pt>30GeV 0% (*)0.3%1.1%1.4%1.6%2.0% Rate [kHz] (|eta|<2.4) 44.535.128.423.220.918.9 Rate [kHz] (|eta|<2.1) 16.011.78.226.485.654.86 (*) efficiency loss computed wrt L1_SingleMu10 L=5E33 24 Muon trigger: efficiency losses and rates

26. CMS Week, Sep. 2011C.-E. Wulz Total RPC trigger rate We do not expect significant non-linear effects in scaling from 3e33 cm -2 s -1 to 5e33 cm -2 s -1 RPC rate on plots below is doubled RUN 176201 (peak lumi: 3.1e33cm -2 s -1 ) 25

27. CMS Week, Sep. 2011C.-E. Wulz Conclusions 26  Improvements to most L1 trigger systems have been made.  Rate capability has been rechecked with data.  Predictions for rates at 5e33 have been made, taking into account pileup.  Preparations to run at 5e33 are well under way.

28. CMS Week, Sep. 2011C.-E. Wulz BACKUP 27

29. CMS Week, Sep. 2011C.-E. Wulz 28 These plots show the ratios of L1 rates measured In two runs with different PU conditions (see slide 21), normalized to the same luminosity.

30. CMS Week, Sep. 2011C.-E. Wulz 29

31. CMS Week, Sep. 2011C.-E. Wulz 30 Recent GMT changes increased the muon rates in latest runs. Hence the rate ratios do not correspond only to the PU effect.

32. CMS Week, Sep. 2011C.-E. Wulz 31

33. CMS Week, Sep. 2011C.-E. Wulz 32