CMS week mar 05 1

Results of the Analysis of 2004 DT Test Beam

C. Battilana and S. Marcellini – INFN Bologna

Trigger Performance:

-Single Muons-Di-Muons -Absorber and Energy Dependance

CMS week mar 05 2

µ beam

MB1MB3 configured as MB2

~ 1 m

Iron slabs5 cm thick

10 x 10 cm²Triggerscintillator

A Sketch of the Experimental Set-Up

CMS week mar 05 3

Single Muon Analysis

Event selection similar to TB2003 analysis.

Muon candidates are selected in MB1 and the output of the local trigger is studied in MB3 (or the other way around)

Some problems to deal with:

- Few Front-End problems- Bad TDCs configuration in MB3 relevant in some cases - Some Theta BTIs were masked by mistake, which turned into a wrong treatment of the uncorrelated Low quality triggers (as Theta Triggers validate uncorr. Low quality Triggers in the Phi view)

CMS week mar 05 4

-30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30858687888990919293949596979899

100

BX Efficiency in Angle

DataEmulated

Angle

BX

Effi

ciency

%Trigger Efficiency at Correct BX vs Angle

Higher efficiency for the emulation due to the uncorrelated Low trigger problem mentioned before.

F.E. problems

Wrong TDC config.

CMS week mar 05 5

-30 -25 -20 -15 -10 -5 0 5 10 15 20 25 302

4

6

8

10

12

14

16

18

20

2nd/1st

Data

Emulated

Angle

2n

d/1

st

%Ghost Rate at Correct BX vs angle

Higher noise rate in the emulation, still due to the Low trigger problemmentioned before (most of the ghosts are uncorrelated Low triggers)

CMS week mar 05 6

Effect of the Iron Absorber vs Beam Energy

50 100 150 200 250 30092

92.5

93

93.5

94

94.5

95

95.5

96

96.5

97

97.5

98

BX Efficiency MB3 (Data)

Data no Iron MB3

Data Iron MB3

Energy

BX

Effi

cie

ncy %

~ 1-2 %

CMS week mar 05 7

Actually when the Track Finder tries to match triggersegments from different stations, it opens a time window of ± 1 BX around the centered BX.

This means that also triggers at BX=±1 with respect to the correct BX can in principle contribute to make a muon Trigger track, if they can be matched with other segments in the rest of the muon detector.

This happens if they have the correct position and bending angle, even if they occur at the wrong BX.

Therefore a fraction of the triggers at wrong BX can be recovered to enhance the effective trigger efficiency.

CMS week mar 05 8

Trigger position (trig. Units)

No iron

With iron

Among the triggers at BX=Correct±1 let’s assume as good (i.e which contribute to the efficiency) only the triggers which occur in the range indidated by the arrows,

CMS week mar 05 9

Trigger position (trig. Units)

The same also for the bending angle of the trigger segment

No iron

With iron

CMS week mar 05 10

50 100 150 200 250 30092

92.5

93

93.5

94

94.5

95

95.5

96

96.5

97

97.5

98

Efficiency Iron

CorrectBX Efficiecy

Total Efficiency Iron

Energy

Effi

cie

ncy

%The effective efficiency can be increased only by about 0.5 % if also triggers at BX=±1 with respect to the correct BX (and with correct position and bending) are also included

CMS week mar 05 1150 100 150 200 250 300

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

0.6

0.65

0.7

CorrectBX±1 Efficiency

Correct BX ±1 no Iron

Correct BX ±1 Iron

Energy

Eff

icie

ncy %

Efficiency gain as a function of beam energy, with and without iron, when triggers occurring at BX next to the correct one are also included.

~ 0.5 % with iron

~ 0.3 % without iron

CMS week mar 05 12

Di-Muon Analysis

As the two stations were often shifted and rotated during the data taking,it is not trivial to select di-muons in one station and check the triggerperformace in the other one

Therefore for the moment themuon pair selection was performedas for 2003 test beam, i.e. each station was treated independently.

We are developing a more accurate di-muonselection

MB3 MB1

CMS week mar 05 13

Di-Muon Selection

Di-muons

N hits in a station (Phi)

N hits in a station (Phi)

All events

After di-muon selection

Two fitted tracks (TDC hits)in the Phi viewwith at least 4 hits andaverage Mean Timer in the espected time range(to reject off time di-muons)

AND

Two fitted tracks (TDC hits)n the Theta view

CMS week mar 05 14

Di-Muon Efficiency

∆x between tracks (cm)

Effi

cie

ncy

2 Trig at BX=OK

2 Trig at BX=OK±1

1 Trig at BX=OK

Data

Emulation

Most of the data usablefor di-muon analysis areat 0 deg. for which effic.is lower than for other trackincident angle.

Good agreeement with 2003 test beam results.

Good matching with emulation, also in view ofthe wrong uncorr. Low triggertreatment, which occurs only on Data and not in theEmulation

No cases with no triggers at all (at least 1 track is alwaystriggered)

CMS week mar 05 15∆x between tracks (cm)

∆x b

etw

een

tri

gg

ers

(t

rig.

unit

s)

Di-Muons: are the two triggers the correct ones ?

Very few ghosts

Correlation between track distance and trigger distance: Ghost triggers lay out of the diagonal band

CMS week mar 05 16

Quality of the Trigger Segments

Li Lo Hi Ho LL HL HH

Li Lo Hi Ho LL HL HH

DataEmulator

1st Trigger Server Track at correct BX

2nd Trigger Server Track at correct BX

Discrepancy with emulatordue to wrong uncorr. Low Trigger treatment and bad TDC configuration in MB3

CMS week mar 05 17

∆x between tracks (cm)

Effi

cie

ncy

No absorber – 0 deg

With absorber – 0 deg Data

Emulation

Data

EmulationSmall drop of efficiencywhen the iron absorberis placed in front of MB3, expecially when tracks are very close in space

CMS week mar 05 18

Incident angles different from zero

∆x between tracks (cm)∆x between tracks (cm)

Effi

cie

ncy

Effi

cie

ncy

Data

Emulation

Data

Emulation0 deg no 0 deg

1 Trig at BX=OK

2 Trig at BX=OK

2 Trig at BX=OK±1

CMS week mar 05 19

Conclusions

• Trigger performances in good agreement with 2003 results.

• New results from energy dependence and the effect of the iron absorber.

• Some refinements of the analysis is the two-muon selection will come soon.

• A written note is in preparation. • Updated results from Track Finder

performaces are expected also expected (Jorge)