CSC Track Finder:
Simulation Results
D.Acosta, A.Madorsky, S.M.Wang
University of Florida
A.Atamanchuk, V.Golovstov, B.Razmyslovich
PNPI
EMU and CMS Week
Sept 1999
Results from the Simulation
CMSIM 114 was used for the detector simulation, and
the LCTs were simulated with an old version of the
LCT simulation (Rowe,Acosta)
A Fortran version of the CSC Track Finder simulation
was used for the study of the track nder
A C++ version of the CSC Track Finder simulation is
completed. Preliminary comparions between the two
versions show good agreement.
Extrapolation Eciency for Single Muon Events
Endcap Region
%
Pt = 3 GeV
ME1-ME2 ME1-ME3
successful extrapolation
= 93.4
81.3
Low Pt
= 77.1
58.1
Medium Pt
= 14.5
19.5
High Pt
= 1.8
3.7
Pt = 5 GeV
successful extrapolation
Low Pt
Medium Pt
High Pt
=
=
=
=
99.1
44.8
53.2
1.2
98.1
46.4
46.8
4.9
Pt = 50 GeV
successful extrapolation
Low Pt
Medium Pt
High Pt
= 99.4
= 0.02
= 0.9
= 98.4
99.4
0.01
1.1
98.2
Overlap Region
Pt = 5 GeV
successful extrapolation
Low Pt
Medium Pt
High Pt
%
MB1-ME2 MB2-ME2
= 100
100
= 48.9
70.9
= 39.9
3.1
= 11.2
26.0
Pt = 50 GeV
successful extrapolation
Low Pt
Medium Pt
High Pt
=
=
=
=
99.8
0.3
0.6
98.9
100
1.8
0.8
97.5
(Note :The chamber eciency was not taken into account)
Final Selection Unit
Eciency of FSU on single muon events
High eciency for high Pt muons ( 100%)
0:5% of events FSU found > 1 track.
bremsstrahlung,
delta rays
0.35
Y x10 (m)
{ Extra LCTs due to
0.3
0.25
0.2
0.15
0.1
0.1
0.15
0.2
0.25
0.3
X x10 (m)
{ Broken track due to sector boundary, failed extrapY x10 (m)
Y x10 (m)
olation
0.065
0.06
0.28
0.26
0.055
0.24
0.05
0.045
0.22
0.04
0.2
0.035
0.18
0.03
0.16
0.025
0.14
0.02
0.08
0.1
0.12
0.14
0.16
0.18
0.2
0.22
X x10 (m)
0.12
0.5
0.6
0.7
0.8
0.9
1
1.1
Z x10 (m)
Eff
Single Muon Track Finding Efficiency (OL + EC)
1
0.75
0.5
Pt = 3 GeV/c
0.25
Eff
0
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
ηgen
1
0.75
0.5
Pt = 5 GeV/c
0.25
Eff
0
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
ηgen
1
0.75
0.5
Pt = 50 GeV/c
0.25
0
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
ηgen
Eff
1
0.8
0.6
0.4
Pt = 50 GeV/c (CMSIM 116 oldLCT)
0.2
0
1
1.2
1.4
1.6
1.8
2
(CMSIM116 old LCT) FSU track Pt=50 GeV
2.2
2.4
ηgen
Eff
Eciency vs (1:05 < < 1:15)
1
0.8
0.6
Pt = 50 GeV/c
0.4
0.2
0
0
10
20
30
40
FSU track (Phi Gen)
50
60
Mod(Φgen,60) (deg)
Eff
Eciency vs ( > 1:2)
1
0.8
0.6
Pt = 50 GeV/c
0.4
0.2
0
0
50
100
150
200
250
(Pt 50 GeV η gt 1.2) FSU track (Phi Gen)
300
350
Φgen
Broken
track due to muon crossing sector boundary
contributes 50% of the events with > 1 found by
FSU for low Pt muons
Contribution to fake tracks due to bremsstrahlung or
delta rays (dominant for high Pt muons) may be lesser
than expected :
Old LCT simulation allows > 1 LCT within 16 cathode strips or anode wires
Look at the dierence in of two LCTs in a single
station
For 10 chambers with 80 cathode strips,
) 16 strips = 2 in For 20 chambers with 80 cathode strips,
) 16 strips = 4 in Only a small fractions of single muon events have two
LCTS that are separated by more than 16 cathode
strips
Preliminary studies using new LCT simulation (Benn)
indicates only 0:04% high Pt single muon events
have > 1 reconstructed tracks in the FSU
Pt Assignment ( Endcap )
Extract
Pt using of LCTs measured in 2 or 3 CSC
stations
One of the of LCT must be measured in ME1
Why do we need 3 CSC stations for Pt measurement ?
σ( 1/Ptrec - 1/Ptgen )/( 1/Ptgen )
Pt Measurement
using 2 CSC stations (ME1-ME2)
1
0.9
Pt = 5 GeV
Pt = 50 GeV
Pt = 10 GeV
Pt = 100 GeV
0.8
0.7
ME1/3
ME1/2
ME1/1
MB1
0.6
0.5
0.4
0.3
0.2
0.1
MB1 / ME1 / ME2
0
0.8
1
Resolution
1.2
1.4
1.6
1.8
2
of 1/Pt is 30% at low Pt
2.2
2.4
ηrec
Muon Rate dN/dηdt (Hz)
Single Muon Trigger Rate in CSC Endcap
10 7
10
L = 1034 cm-2s-1
6
10 5
50%
10 4
40%
10 3
10 2
30%
10
1
10
10
20%
CSC resolution from CMSIM
-1
10% resolution
PYTHIA6
-2
1
Require
10
10
2
Effective PT Threshold (GeV/c)
that the 1/Pt resolution to be 30% or better
for the the trigger rate to be below 1 kHz per unit
rapidity
Using of LCTs measured in 3 CSC stations
∆Φ23 (deg)
Pt=3 GeV
Pt=5 GeV
Pt=7 GeV
Pt=10 GeV
5
4
3
2
1
0
-1
-2
-3
-4
-5
-2
1.6 < η < 2.0
0
2
4
∆Φ23 vs ∆Φ12
Contributions
6
8
10
∆Φ12 (deg)
from low Pt muons can be well separated from the muons of higher Pt when of the
LCTs are measured in 3 stations
) improves the 1/Pt resolution at low Pt
σ( 1/Ptrec - 1/Ptgen )/( 1/Ptgen )
Pt Measurement using 2 VS 3 CSC stations
0.7
Pt = 5 GeV (2 Stn)
(ME1-ME2)
0.6
0.5
ME1/3
MB1
Pt = 5 GeV (3 Stn)
(ME1-ME2-ME3)
ME1/2
ME1/1
0.4
0.3
0.2
0.1
0
0.8
1
Signicant
1.2
1.4
1.6
1.8
2
2.2
2.4
ηrec
improvement in the 1/Pt resolution using
3 CSC stations
Pt Distributions from Pt Assignment Unit
Entries/GeV
muon events generated at xed Pt
Entries/GeV
Single
3500
3000
3000
2500
2500
2000
2000
1500
1500
1000
1000
500
500
0
2
4
6
8
10
0
1400
1200
1000
10
Pt (GeV)
Pt assign Pt=5 GeV
Entries/GeV
Entries/GeV
Pt (GeV)
Pt assign Pt=3 GeV
5
800
200
175
150
125
100
600
75
400
50
200
0
25
10
20
30
Pt (GeV)
Pt assign Pt=10 GeV
0
50
100
Pt (GeV)
Pt assign Pt=50 GeV
9000
Entries/GeV
-1
Pt Assignment (for Pt=3 GeV 1.6 < η < 2.0)
mean=0.340851
8000
7000
sigma=0.0596905
6000
5000
4000
3000
2000
1000
0
0.1
0.2
0.3
0.4
0.5
0.6
-1
1/Pt (GeV )
1/Pt assign Pt=3 GeV
Entries/GeV
-1
Pt Assignment (for Pt=10 GeV 2.0 < η < 2.4)
45000
mean=0.101545
sigma=0.0325276
40000
35000
30000
25000
20000
15000
10000
5000
0
0.05
0.1
0.15
0.2
1/Pt assign Pt=10 GeV
0.25
0.3
-1
1/Pt (GeV )
Trigger Studies on Minimum Bias Events
Generated 500
k min. bias events with Pythia
The events were sent through detector simulation
(CMSIM 116)
The Fortran version of the CSC Track Finder
simulation was used to search for tracks in CSC
Only trigger on tracks that contain a track stub in
ME1
Studies limit to the Endcap region only
Entries
Distribution of Tracks Found in CSC
200
175
150
125
100
75
50
25
0
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
ηrec
Entries/GeV
Pt Distribution of Tracks Found in CSC
10 2
10
1
10
-1
0
20
40
60
80
Pt assign
100
120
140
Pt (GeV)
Preliminary Estimate of Single Muon Rate
Rates are estimated for :
Pt reconstructed using 2-stns or 3-stns only, or 2/3stns
in dierent ranges
1:2 <j j< 2:1, 1:2 <j j< 2:3, j j> 1:2
Rate dN/dηdt (kHz)
Single µ Rate (Min Bias sample) (2-Station Pt Assignment)
10 3
|η| > 1.2
1.2 < |η| < 2.3
1.2 < |η| < 2.1
10
2
10
1
L = 1034 cm-2s-1
10
-1
1
10
10
2
Ptmin (GeV)
Rate dN/dηdt (kHz)
Single µ Rate (Min Bias sample) (3-Station Pt Assignment)
10 3
|η| > 1.2
1.2 < |η| < 2.3
1.2 < |η| < 2.1
10
2
10
1
L = 1034 cm-2s-1
10
-1
1
10
10
2
Ptmin (GeV)
Rate dN/dηdt (kHz)
Single µ Rate (Min Bias sample) (2/3 Station Pt Assignment)
10 3
|η| > 1.2
1.2 < |η| < 2.3
1.2 < |η| < 2.1
10
2
10
1
L = 1034 cm-2s-1
10
-1
1
10
10
2
Ptmin (GeV)
Preliminary results show that:
Rates using 3-station Pt assignment is an order of
magnitude lower than rates using 2-station Pt assignment (for Ptmin > 10 GeV)
Trigger rates can also be greatly reduce if one limits
to tracks in the region j j< 2:1
Summary/Plans
Now have Fortran and C++ versions of the CSC Track-
Finder simulation
Simulation shows high eciency in nding high Pt
tracks
Pt resolution improves signicantly when 3 CSC stations are used in the determination of Pt
Perform simulation studies using C++ version of TrackFinder
Include Pt Assignment for Overlap region
Generate weighted M.B. events (to increase statistics
at high Pt)
Study di-muon rate