Level-1 Trigger

Level-1 TriggerCMS Week, Brussels

14 Sep. 2011

C.-E. WulzDeputy 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

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

Trigger menu development

currently running with “3e33 menu”

− menu designed for instantaneous luminosity of 3×1033 cm-2 s-1

− small updates applied last week

one more menu planned for 2011 proton run

2


Recent L1 trigger developments

new muon combination scheme proposed in GMT− instead of taking minimum PT 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 PT 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

3


Golden eta region: 1.2 < η < 2.12 or 3 station tracks with ME1

Improved ME1 CLCT patterns for 2 station tracks: - curves PT ≥ 5 GeV the same for PTLUT2010 and PTLUT2011 as expected; CLCT pattern starts to work from PT > 5 GeV - Efficiency below threshold drops from 5-10% (2010) to ~2% (2011) for PT thresholds ≥ 7 GeV and up - Significant improvement in 2011 compared to the 2010 PT assignment, especially for PT ≥ 7 GeV, lowering the trigger rate

CSCTF PT assignment

4


• In 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 pT > 8GeV/c

Offline muon pT > 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

5 CMS Week, Sep. 2011


Stability of L1RPC after automatic HV versus pressure correction

• Variation of chamber efficiency affects the absolute trigger efficiency (difficult to follow) and pT spectrum

• check fraction of L1RPC candidates with given pTCode vs all.

• after applied modifications RPC trigger pT 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

6


RPC data synchronisation

• Only small modification of timing settings done in 2011

7


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”)

8


L1 jet energy calibration

2011 SO FARCORRECTED

2011 DATA

UNCORRECTED

2011 DATA

Unco

rr

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 PT

ΔR<0

.5 m

atch

bet

ween

L1

and

REC

O je

ts

9


L1 jet energy calibration

10

New jet energy corrections derived from Monte Carlo using JetMET code Tests on existing data and Monte Carlo Extends high-PT region and improves low-PT region a little Test run taken and validated ready for physics ➔

NEW CORRECTIONS

2011 DATA

New corrections

Old corrections

Monte Carlo

±10%



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

11


“post-quiet unpaired bunches”

beam 1

beam 212



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

13


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

14


- 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 PT/ET cut which is unprescaled in all prescale columns of the menu

L1 trigger cross section monitoring

15


- 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

16


3e33(EG20)

2e33(EG15)

1.4e33(EG12)~J

uly

~Aug

ust

- Jumps due to the different selection of monitored trigger object- Can check stability of the triggers

P. Musella, J. Pela

17

Trigger cross section history

CMS Week, Sep. 2011C.-E. Wulz 18

Prediction based on3e33 data(PU increase not included)

Predictions for 5e33 based on the 3e33 dataData 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 besustainable.Note that the rate in cross-triggers starts to be large.


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)

19 CMS Week, Sep. 2011C.-E. Wulz


SingleMu14_Eta2p1

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


The L1 menu (L1Menu_Collisions2011_v5) deployed for the 3e33 menu

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)


PU effect on total L1 rate in recent runs

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.)


- Study per PT cut between 10-20 GeV/c with data from 1-2e32 running- Preparation of the 5e33 menu- Turn-on positions and slopes are OK

23

Muon trigger PT cuts: turn-on curves


L=5E33

|eta|<2.4|eta|<2.1

- Rate measured using NanoDST data, projected to 5E33 luminosity- >70% of total rate from |eta|>2.1- Higher PT cuts less and less effective at high - Introduced cut at 2.1- Keep lower L1 thresholds- Some gain in plateau efficiency

L1 Eta cut

2424 CMS Week, Sep. 2011C.-E. Wulz

Muon trigger PT cuts: rates


Threshold 10 12 14 16 18 20

Eff loss for pt>30GeV 0% (*) 0.3% 1.1% 1.4% 1.6% 2.0%

Rate [kHz](|eta|<2.4)

44.5 35.1 28.4 23.2 20.9 18.9

Rate [kHz] (|eta|<2.1)

16.0 11.7 8.22 6.48 5.65 4.86

(*) efficiency loss computed wrt L1_SingleMu10

L=5E33

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Muon trigger: efficiency losses and rates


Total RPC trigger rate • We do not expect significant non-linear effects in scaling from 3e33 cm-

2s-1 to 5e33 cm-2s-1

• RPC rate on plots below is doubled

RUN 176201 (peak lumi: 3.1e33cm-2s-1)

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Conclusions

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.


BACKUP


L1_SingleJet16L1_SingleJet36L1_SingleJet52

L1_SingleJet52_CentralL1_SingleJet68



L1_DoubleJet36_CentralL1_DoubleJet44_Central

L1_DoubleJet52L1_DoubleJet52_CentralL1_DoubleJet64_Central

L1_DoubleTauJet32_Eta2p17L1_DoubleTauJet40_Eta2p17L1_DoubleTauJet36_Eta2p17L1_DoubleTauJet44_Eta2p17

L1_TripleJet_36_36_12_CentralL1_TripleJet28_CentralL1_QuadJet20_CentralL1_QuadJet28_Central

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

PU effect from 2.2 to 3e33: Jet seeds

These plots show the ratios of L1 rates measured In two runs with different PU conditions (see slide 21),normalized to the same luminosity.


L1_SingleEG5

L1_SingleIsoEG12

L1_SingleIsoEG12_Eta2p17

L1_SingleEG18

L1_SingleEG22

L1_SingleEG12

L1_SingleEG15

L1_SingleEG20

L1_SingleEG30

L1_DoubleEG3

L1_DoubleEG5

L1_DoubleEG10

L1_DoubleIsoEG10

L1_DoubleEG_12_5

L1_DoubleEG_12_5_Eta1p39

L1_TripleEG5

L1_TripleEG7

L1_TripleEG_8_5_5

L1_TripleEG_8_8_5

0.9 0.95 1 1.05 1.1 1.15 1.2

PU effect from 2.2 to 3e33: EGamma seeds


Recent GMT changes increased the muon rates in latest runs.Hence the rate ratios do not correspond only to the PU effect.

L1_SingleMuOpen

L1_SingleMu3

L1_SingleMu5_Eta1p5_Q80

L1_SingleMu7

L1_SingleMu10

L1_SingleMu12

L1_SingleMu12_Debug

L1_SingleMu14_Eta2p1

L1_SingleMu16

L1_SingleMu16_Eta2p1

L1_SingleMu20

L1_SingleMu25

L1_DoubleMu0

L1_DoubleMu3

L1_DoubleMu3p5

L1_DoubleMu5

L1_DoubleMu0_HighQ

L1_DoubleMu0_HighQ_EtaCuts

L1_DoubleMu_5_Open

L1_TripleMu0

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

PU effect from 2.2 to 3e33: Muon seeds (note: also GMT changes)


L1_ETM100

L1_ETM20

L1_ETM30

L1_ETM50

L1_ETM70

L1_HTT50

L1_HTT100

L1_HTT150

L1_HTT75

L1_HTM50

L1_ETT220

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

PU effect from 2.2 to 3e33: Global Sums


L1_Mu3_EG5L1_MuOpen_EG12

L1_Mu5_EG12L1_Mu7_EG5

L1_Mu12_EG5L1_DoubleMuOpen_EG5L1_MuOpen_DoubleEG5

L1_EG18_ForJet16L1_EG5_DoubleJet20_Central

L1_EG5_HTT75L1_EG5_HTT100L1_EG5_HTT125

L1_DoubleEG5_HTT50L1_DoubleEG5_HTT75

L1_ETT300_EG5L1_Mu10_Eta2p1_DoubleJet_16_8_Central

L1_Mu0_HTT50L1_Mu0_HTT75

L1_Mu3_Jet16_CentralL1_Mu3_Jet20_CentralL1_Mu3_Jet28_CentralL1_Mu7_Jet20_Central

L1_Mu10_Jet36_CentralL1_Jet52_Central_ETM30

L1_HTT50_HTM30L1_HTT50_HTM50

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

"PU effect from 2.2 to 3e33: Cross-triggers"

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Level-1 Trigger