Cosmic Rays in ALICE

• SPD TRIGGER– Analysis runs with B=ON – Some simulations

• ACORDE TRIGGER– New algorithm for cosmic muons– Analysis run with B=ON

SPD TRIGGER RUN : 60824

RUN without magnetic field

Good tracking in TPC

Lot of TPC clusters

141 tracks

Iron interaction

Mu Photonuclear intercation ???

SPD TRIGGER RUN : 60824

RUN without magnetic field

Good tracking in TPC

Lot of TPC clusters

707 tracks

Iron interaction

Mu Photonuclear intercation ???

Cosmic events with SPD trigger without magnetic field

• Analysis of high multiplicity events • Run :

– 60281 8h 6m 9 events > 6 tracks– 60305 2h 02m 3 events > 6 tracks– 60824 8h 12m 210 events > 6 tracks and 20 events > 20 tracks SPD trigger 7-8 events per minute

We can estimate at least 1 event per hour with high multiplicity Probably muon intercation in iron

SPD TRIGGER with B=ON

• RUN 62107 night 8h 36min • RUN 62102 evening 5h 25min• RUN 62084 afternoon 4h 41min• RUN 62029 evening 2h 53min• RUN 62006 afternoon 2h 41min• RUN 62022 evening 1h 06min

– October 7/9 2008

SPD TRIGGER : high multiplicity events

• RUN 62107 – 7 events with Ntracks>18

• 2 + (1) events interaction in iron• 1 probable interaction in ITS• 3 bad events

• RUN 62102– 3 events with Ntracks>18

• 2 bad events• 1 no display

Mu interacting where ?

RUN = 62107

Chunk = 90

Event = 868

Tracks = 19

Mu interacting in iron

RUN = 62107

Chunk = 70

Event = 87

Tracks = 23

Mu interacting in iron

RUN = 62107

Chunk = 180

Event = 4325

Tracks = 27

Previous event 4325

MUONP = 138 GeV

MUONP = 183 GeV

27 tracks

9 particles

2 missing

Simulations of muon interaction in iron

• Muon in the range 700-1000 GeV• Starting at Y=800 cm (above the magnet)• Geant• Fluka• Only few event now (< 100)

High energy muon interacting in iron

Muon -

Pmu=930 GeV

Yint=573 cm

Mu e+ e-

Pe+=25 GeVPe-=37 GeV

Previous event seen by TPC

Interaction point

Previous event : TPC recostruction

Tracks = 60

2 tracks for theprimary muon:

Pmu=396 GeV

Pmu=306 GeV

Instead of

Pmu = 865 GeV ????

SPD TRIGGER with B=ON

• Few events with muon interactions in iron with respect the expectation with B=OFF

• Probably all events are e+ e- pair production created by muon with Emu > 500 GeV

• It should be necessary a long run with B=ON (1 day) with good data and reconstruction in TPC.

• Next step : Forced Geant or Fluka to create events with muon nuclear photoproduction interaction in iron

• Give an expectation of these events• Give topology of these events for a possible TOF Trigger

ACORDE Trigger Analysis

File:/Volumes/MRC/RunsAliEn/Run62107/08000062107000.460/AliESDs.root, N. of Event:8560, ACORDE Multiplicity:35, No. of ESD's tracks:148

How many muonswe have ?

17

Float_t fCutMaxD=5;Float_t fCutMaxDz=40;Float_t fCutTheta=0.03;Float_t fCutMinDir=-0.99;Float_t kMaxD=1000;

Double_t *p0 = tr0->GetParameter();Double_t *p1 = tr1->GetParameter();

if (TMath::Abs(p0[3]+p1[3])>fCutTheta) return kFALSE;if (TMath::Abs(p0[1]-p1[1])>fCutMaxDz) return kFALSE;if (TMath::Abs(p0[0]+p1[0])>fCutMaxD) return kFALSE; Double_t d0[3], d1[3];tr0->GetDirection(d0); tr1->GetDirection(d1); if (d0[0]*d1[0] + d0[1]*d1[1] + d0[2]*d1[2] >fCutMinDir) return kFALSE;

Float_t minDist=1000;

// calculate distanceFloat_t dy = (tr0->GetY()+tr1->GetY());Float_t sy2 = tr0->GetSigmaY2()+tr1->GetSigmaY2();Float_t dphi = (tr0->GetAlpha()-tr1->GetAlpha()-TMath::Pi());Float_t sphi2 = tr0->GetSigmaSnp2()+tr1->GetSigmaSnp2();Float_t dtheta = (tr0->GetTgl()-tr1->GetTgl());Float_t stheta2 = tr0->GetSigmaTgl2()+tr1->GetSigmaTgl2();Float_t normDist = TMath::Sqrt(dy*dy/sy2+dphi*dphi/sphi2+dtheta*dtheta/stheta2);if (normDist>minDist) return kFALSE;

return kTRUE;

Bool_t IsPair(AliExternalTrackParam *tr0, AliExternalTrackParam *tr1) IsPair?

Cuts defined by TPC people in TPC’s cosmic calibration

Get the params of both tracks

If both tracks are out of the cuts we don’t have a cosmic muon

Get the direction of both tracks. If they are not in the same direction both belongs to some other kind of event

Calculate the distance between both tracks. If it is bigger than 10 cms. Both tracks don’t belong to the same track

If both tracks “pass” the previous filter then we have a COSMIC MUON TRACK !!!!

Algorithm to match the tracks and get muons

Mario Rodriguez

18

Number of Event: 18, Number of Tracks: 3, Number of Muons: 0

Delta Ray?

Test on algorithmNew Algorithm based on the classes :AliTPCcalibCosmic.cxx and AliESDCosmic.cxx by Marian Ivanov

19

Trigger: D0ASL , Number of Event: 1341, Number of Tracks: 2, Number of Muons: 1, Number of ACORDE fired Modules:1

Very beautiful Single Muon Event triggered by ACORDE

20

Trigger: D0LSR , Number of Event: 14855, Number of Tracks: 79, Number of Muons: 0, Number of ACORDE fired Modules:0

Also with another trigger we are counting very well !!!

21

Trigger: D0ASL , Number of Event: 716, Number of Tracks: 58, Number of Muons: 3, Number of ACORDE fired Modules:1

But, CAUTION, even though here we have an event from laser trigger of TPC calibration, the trigger cluster is from ACORDE!!!

N. TPC tracks vs ACORDE modules

RUN 62107

RUN 62107, MAGNETIC FIELD ONStart Time:09/10/2008 00:03:37End Time:09/10/2008 08:39:39Duration:Days: 0Hours: 8Minutes: 36Seconds: 2

Summary ACORDE

• New software to match tracks to get exact number of muons under construction and test

• Study of the runs with B=ON– Muon Multiplicity, Energy distribution, Arrival

Direction (Teta, Phi)Presentation at next Physics Forum

• Hardware 15 modules equipped with new photubes (in these days)