detection of atmospheric muon bundles using alice detectors a. fernández tellez universidad...

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


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


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


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)


ACORDEACORDE geometry scheme


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 %


TOFTOF trigger

TOF clusters (magnetic field: 0.5 T)

TOF clusters (magnetic field: 0 T)

Tracks reconstructed by the TPC


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


•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


# 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


Trigger type distribution


Muon multiplicity distribution, 4 trigger types


MMD: TOF single and cosmic


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


Zenith and azimuth distribution of muons


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


Vertical muons0o<Teta<20o

Estimated error around 20% at P=100 GeV/cusing Pcov.

Uncorrected muon momentum distribution


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


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

detection of atmospheric muon bundles using alice detectors a. fernández tellez universidad...

Documents

tpc slide

tpc detectors

tpc clusters

matched tpc tracks

trigger muon chambers

alice tpc collaboration

muon crosses

muon spectrometer