Detection of atmospheric muon bundles using ALICE detectors
A. Fernández TellezUniversidad Autonoma de Puebla
for the ALICE Collaboration
VIII Simposio Latinoamericano de Física de Altas Energías - SILAFAE 2010Valparaíso, ChileDec. 10th 2010
Detection of atmospheric muon bundles using ALICE detectors
M. Rodríguez, A. F. (BUAP) B. Alessandro, M. A. Zubieta (Torino)V. Canoa (Cinvestav)E. Cuautle (UNAM)
ALICE Experiment at LHC
ALICE located 40 m. underground30 m of rock (molasse)10 m of air
Threshold Muon Energy ~ 15 GeV
Arturo Fernández Téllez - Dec. 10th. 2010, SILAFAE 2010
ALICE experimental hall during assembly
Arturo Fernández Téllez - Dec. 10th. 2010, SILAFAE 2010
ALICE subsystemsDetectors used for cosmics in the central part :Trigger : ACORDE, TOF, SPD, Tracking : TPC
Detectors used for horizontal muons :Trigger Muon Chambers Tracking Muon Chambers
Arturo Fernández Téllez - Dec. 10th. 2010, SILAFAE 2010
Outline
- Muons with central detectors : August-Sept, 2009, Feb. 2010
-Triggers: SPD, TOF, ACORDE
-Tracking : TPC Angular distribution Muon multiplicity distribution Momentum resolution analysis Momentum spectrum
- Muons with muon spectrometer : August-Sept, 2009
• Trigger and Tracking
• Event and selection
• Momentum spectrum
•- Final Remarks
Arturo Fernández Téllez - Dec. 10th. 2010, SILAFAE 2010
Trigger detectors
SPD : triggers when a muon crosses two layers of SPD detector: SCO.
ACORDE : 60 scintillatorsTrigger coincidence of two scintillators : AMU or SL0 (Multi and Single Muon Trigger)
TOF cylinder of MRPC surrounding the TPC two types of trigger :1 pad up 1 pad down +- 3 pads : TOF Single (OB3)4 pads everywhere : TOF Cosmic (OCP)
Arturo Fernández Téllez - Dec. 10th. 2010, SILAFAE 2010
ACORDEACORDE geometry scheme
Arturo Fernández Téllez - Dec. 10th. 2010, SILAFAE 2010
TOF
The TOF detector covers an effective area for all φ and 45 ≤ θ ≤ 135. This area is around 160 m2. It will identify charged particles.
Temporal resolution < 100 ps
Efificiency > 95 %
Arturo Fernández Téllez - Dec. 10th. 2010, SILAFAE 2010
TOFTOF trigger
TOF clusters (magnetic field: 0.5 T)
TOF clusters (magnetic field: 0 T)
Tracks reconstructed by the TPC
Arturo Fernández Téllez - Dec. 10th. 2010, SILAFAE 2010
Tracking detector and type of events
Muon Interaction Event
Standard Muon Event (multimuon)
TIME PROJECTION CHAMBER (TPC) :ALICE TPC Collaboration, J. Alme et al., "The ALICE TPC, a large 3-dimensional tracking device with fast readout for ultra-high multiplicity events.", Physics. Ins-Det/10011950 (2010).
A muon is reconstructed by the TPC as two tracks : up , down
up up
down down
A matching algorithm connects track up with down to count one muon The momentum is given for the two tracks : Pup and Pdown
Single muon
Arturo Fernández Téllez - Dec. 10th. 2010, SILAFAE 2010
•Find parallel tracks, match the TPC tracks, count the muons (single TPC track, matched TPC tracks)•N. TCP clusters > 30 (matched tracks)•N. TPC clusters > 50 (single tracks)•P > 0.5 GeV•Cos(DeltaDirection) > 0.990• |Z-Zo| < 250 cm |X-Xo| < 165 cm • DeltaDist < 2 cm for matching
•Tested with real multimuon events (up to 200 tracks)
Algorithm for matching TPC tracks
Arturo Fernández Téllez - Dec. 10th. 2010, SILAFAE 2010
# RunTime [h]
# EventsOB3OCPAMU
# Events Mu > 0
OB3 OCPAMU
Purity Rate OB3 [Hz]
Purity Rate OCP [Hz]
Purity Rate AMU [Hz]
# Interaction Events
# Multi- Mu Events
83811 9.48 3422599 719832 20 1 0.03 152 152
83775 1.27 580925 148666 30.1 1.8 0.05 29 19
83802 1.05 382985 81830 20.5 1.1 0.03 18 15
84148 6.4 2720090 682773 28 1.6 0.04 103 98
84205 4.5 1681171 424331 24.7 1.4 0.04 84 76
84254 7 2330994 587554 22 1.3 0.03 99 81
84389 2.23 599723 151642 17.8 1 0.03 33 34
84420 5.12 1958776 495292 25.4 1.4 0.04 80 92
84455 4.43 1883982 478493 28.3 1.6 0.04 98 82
84479 1 377985 96761 25.4 1.5 0.04 19 18
84993 1.52 460389 120291 20.7 1.2 0.03 17 24
85024 1.35 493870 128554 24.9 1.4 0.04 18 18
85031 0.51 304872 79945 41 2.4 0.06 9 10
85032 0.43 14388 3759 2.3 0.13 0.004 1 0
85034 11 3906585 1023590 24.4 1.4 0.04 197 161
Total 57.29 5223313 957 880
Run table conditions
Arturo Fernández Téllez - Dec. 10th. 2010, SILAFAE 2010
Trigger type distribution
Arturo Fernández Téllez - Dec. 10th. 2010, SILAFAE 2010
Muon multiplicity distribution, 4 trigger types
Arturo Fernández Téllez - Dec. 10th. 2010, SILAFAE 2010
MMD: TOF single and cosmic
Arturo Fernández Téllez - Dec. 10th. 2010, SILAFAE 2010
C Side
A Side
Zentih & Azimuth Angles for Cosmics
x
Azimuth Angle
C SideA Side
Zenith Angle
y
z
muon
Z
Y
X
Angular distributions
Arturo Fernández Téllez - Dec. 10th. 2010, SILAFAE 2010
Zenith and azimuth distribution of muons
Arturo Fernández Téllez - Dec. 10th. 2010, SILAFAE 2010
A SIDE
C SIDE
SHAFTSHAFT
Zenith Angle y
x
zAzimuth
Angle
C SideA Side
:From simulation studies we see that the measurement of the momentum using the fit of the whole muon track length (Pcov) instead of using up and down separately (Pweight) improve the resolution by a factor ~ 3.:
Resolution at 100 GeV/c ~ 50% using up and down separately (Pweight)Resolution at 100 GeV/c ~ 20% using the whole muon track length (Pcov)
Muon momentum resolution with data
Arturo Fernández Téllez - Dec. 10th. 2010, SILAFAE 2010
Vertical muons0o<Teta<20o
Estimated error around 20% at P=100 GeV/cusing Pcov.
Uncorrected muon momentum distribution
Arturo Fernández Téllez - Dec. 10th. 2010, SILAFAE 2010
DATA TAKING: FEBRUARY 2010
Trigger : ACORDE and SPDTime : 2.2 effective daysTwo events with high muon multiplicity
High Muon Multiplicity Events
Time : 2.2 effective days89 muons182 muons
SimulationTime : 30 effective days
Main Characteristics : Event with 182 m
Mean Zenith Angle : 40°Mean Azimuth Angle : 212°Density of muons : 12 m/m2
Mean Momentum : 123 GeV/c
Main Characteristics : Event with 89 m
Mean Zenith Angle : 41°Mean Azimuth Angle : 69°Density of muons : 6 m/m2
Mean Momentum : 189 GeV/c
Arturo Fernández Téllez - Dec. 10th. 2010, SILAFAE 2010
Ratio
World ratio ~ 1.3, P < 100 GeV/cALICE uncorrected ratio ~1.31, P < 100 GeV/c
Θy negative
Θy positive
Muon momentum threshold ~ 4GeV/c (due presence of absorbers)
Length detector ~ 17 m (from the interaction point)
Length detector ~ 13 m (from first tracking station)
Study of horizontal muons
Runs of August and September 2009Total time ~ 240 h → 10 days Magnetic field → 0.5 TN. Total Events → 200372N. Events with at least one muon → 8194 N. Good events (selected) → 5876
Data sample
Selection of good events
Cut to select “good events” :ThetaY > 0 5876 events
Angular Distributions and Selection of the events
70o< Zenith < 80o
85o< Azimuth < 95o 5876 events after these cuts 2862 events
Energy loss from Surface to ALICE
Simulation to obtain the energy loss by m+ and m- crossing the rock from Surface to ALICE experiment at different Zenith Angles
Uncorrected Muon Momentum Distribution (700-800)
ALICE LEVEL
SURFACE LEVEL
Final remarks
• ALICE can study atmospheric muons with central detectors (vertical muons) measuring : Num. of muons, Momentum, Charge, Direction.
• In the future analysis of the correlations of these quantities for composition studies
• Measurement of the Ratio μ+/μ- for vertical muons with the central detectors (00-200) and for horizontal muons with muon spectrometer (700-800) in progress.
• Study and search of events of very high muon multiplicity can be a test for hadron interaction models