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ALICE PID@ATHENS K/ π  μν Yields in one year of Pb-Pb running of the ALICE experiment

ALICE PID@ATHENS K/ π  μν Yields in one year of Pb-Pb running of the ALICE experiment. Martha Spyrpoulou-Stassinaki University of Athens. Outline. Introduction Kinematics of K/ π decays Analytical Calculation of the Geometrical Acceptance

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ALICE PID@ATHENS K/ π  μν Yields in one year of Pb-Pb running of the ALICE experiment

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  1. ALICE PID@ATHENS K/πμν Yields in one year of Pb-Pb running of the ALICEexperiment Martha Spyrpoulou-Stassinaki University of Athens

  2. Outline • Introduction • Kinematics of K/π decays • Analytical Calculation of the Geometrical Acceptance • Calculation of the Geometrical Acceptance from Simulation • Preliminary calculation of the Kink Reconstruction Efficiency • Expected Yields of Kaon kinks in one year of running of the ALICE experiment • Summary

  3. The ALICE Detector at CERN LHC ALarge Ion Collider Experiment

  4. ATHENS@ALICE (Athens-Phys.Dep.)Quark-Gluon-Plasma (~7 TeV/nucleon) Staff memb. Post-Doc. Graduate St. A. PETRIDIS Μ. STASSINAKI E.TSILIS M.VASSILIOU A.BELOGIANNI P.GANOTI S.POTIRAKIS P.CHRISTAKOGLOU G.GEORGOPOULOS F.ROUKOUTAKIS M.FRAKGIADAKIS G. TAGRIDIS +10Phys. Students S.TATSIS (Techn.) Contribution to QGP Study 1.Charge Flactuations/Balance function 2.Flactuations of Particle density 3. Strange Particle Production (Κ, Λ(1520)....) 4. Quarkonium Production(J/Ψ,Υ) Contribution to Detector’s develop. 1.Design, development & construction of H.V. distribution system for the TRD 2.Integration of the ALICE DAQ system and monitoring development for the ALICE Forward detectors(Τ0,V0,FMD) 3.Design and development of the Control System (DCS) for the TRD 4.Design-development of a monitoring System for the Gate Pulser of theTPC 5.Software development for PID in cent ALICE detectors(TPC,ITS,TRD) 6.Development of a kinematic method for Particle Identification(PID) in ALICE experiment

  5. PID in ALICE ALICE PPR CERN/LHCC 2003-049

  6. ALICE Experimental Setup is a very good tracker and most of the QGP signatures require Particle Identification (PID) For example strange quark production in hot QCD is far from being understood. Experimental cross-checks requiring high statistics and precision in a large Pt range are needed to fully explore the properties of dense matter. Kaon is the lightest strange hadron, with a high branching ratio to muonic decay channel ( 63,26%) and large Geometrical acceptance in the central barrel of ALICE. So the reconstruction of the kink topology is a Key technique for identifying kaons over momentum range wider than that achieved by combining PID signals from different detectors. The decay vertex is identified by selecting tracks of the same sign.

  7. Kaonand Pion decays 3 prong-decay bgr. kinks kinks

  8. Kinematics of kink K/π to μν decays The momentum of the daughter muon in the K/π rest frame is 236 and 30 MeV/c respectively. This is the maximum Qt value of the muon in the Lab frame. The muon decay angle in the parent rest frame and in the lab system are connected as: The maximum Lab. Decay angle is :

  9. The next ‘two dimensional’ plot is shown : momentum versus lab decay angle between daughter and mother tracks for Kaon and Pion to muon decays, together with the theoretical curves for the maximum Lab decay angle

  10. As a first step an estimation of K/π yields from kink decays in one year of running of Pb-Pb in ALICE is required in a higher momentum region, especially above 4 GeV where the K/π identification is poor from the ALICE detectors and the region is important for the dense matter study. For such a study the number of expected yield is given by: N(observed) = N(generated) x Geom.Acc x Rec. Eff. So, the spectra (e.g. η, Pt ) for generated particles are needed, as well as well as the calculation of Geometrical Acceptance and Reconstruction efficiency

  11. Analytical Calculation of the Geometrical Acceptance The Geometrical Acceptance (A)inside a given volume is defined as the ratio: A = Decayed Particles(inside the volume) / Produced Particles If No particles are produced at some point xo the number of those that survive after distance x is: N=No e-x/λD So: Where:

  12. Combining the last two equations we result in In order to express the acceptance A as a function of the particle’s momentum and pseudorapidity, we write x in cylindrical coordinates. Where R is the radius of the cylinder and φ the azimuthal angle. If θ is the polar angle then (z=xcosθ, R=xsinθ):

  13. It is also known that: Now the acceptance can be written as: After some trivial mathematical calculations we obtain:

  14. Analytical Geom.Acc. of Kμν inside TPC (R=1.2-2.2m) and -0.9 < η < 0.9

  15. Geom.Acc. of Kμν inside TPC (R=1.2-2.2m) and -0.9 < η < 0.9

  16. Analytical Geometrical Acceptance as a function of pT -0.9 < η < 0.9 and R=1.2-2.2m

  17. Comparison of Theoretical Acceptance with Simulation The Geometrical Acceptance has also been studied by using the Aliroot Simulation inside the same volume (R:120-220cm). 100.000 K+ and 100.000 K- have been generated with uniform momentum distribution in the region 0-10GeV/c and with -0.9 < η < 0.9. The acceptance has been studied as a function of p and pT

  18. Simulated Geometrical Acceptance as a function of p

  19. Simulated Geometrical Acceptance as a function of pT

  20. Reconstruction Efficiency Study A preliminary calculation of the Kink Reconstruction Efficiency has been done in the momentum region 0-10GeV/c in bins of 500MeV/c. In each bin we generated 2000K+ and 2000K- with uniform momentum distribution. We run all the steps of the Track Reconstruction chain in the framework of Aliroot using the appropriate files (AliGenInfo.C, AliESDComparisonMI.C).

  21. Generated Kinks in R=1.2-2.2m Reconstructed Kinks in R=1.2-2.2m

  22. Kaon Yields in one year of running of the ALICE experiment In order to calculate the expected yields of Kaons in one year of runningof the experiment we generated 2000 HIJING events with dN/dη=6000 in thepseudorapidity range |η| < 1. In the next plots are shown: The Momentum Distribution of the generated Kaons, the Geometrical Acceptance, the Reconstruction Efficiency and finally the resulting Yields of Ks as a function of their transverse momentum are:

  23. The fit of the pT distributions of the generated Kaons and Pions (as well as of those for the yields calculation) has been performed by using the function From the function we find that we expect : kinks from Kaons, pions decaying to μν with 386919 542049 pT : 3-4GeV/c 80525 69235 pT : 4-5GeV/c 26666 11728 pT : 5-7GeV/ 3290 373 pT : 7-11GeV/c 100 kaon-kinks for pT > 11 GeV/c, 100 pion-kinks for pT > 8 GeV/c

  24. Yields of Kμ ν in 107 Pb-Pb events | η| < 0.9, dN/dη =6000 Fit Function in the region 1 < pT < 30GeV/c

  25. Summary K/π PID through muon + neutrino decay will provide good statistics in a wide momentum range. Reasonable kaon-kinks statistics is expected in the higher PT region 5-10 GeV/c. The presented results are coming from the central TPC volume. In the near future, when the combined tracking will be available, the study will be extended to bigger volume, covered by more than one detector. The K/π identification is important for ALICE for studying singleparticle spectra distributions, K/π ratios and Reasonαnce production,for example K*(892), Φ(1020), Λ(1520).

  26. Overview of the Forward Detectors • FMD (Forward Multiplicity Detector) NBI+INR • 5 Si-strip Ring counters with 51.200 channels • 1.7<  < 5.0; -1.7<  <-3.4 • Precise off-line charged particle multiplicity for A+A, p+p • Fluctuations event-by-event, flow analysis • V0 (Centrality and collision vertex) Lyon+Mexico • 2 arrays of 32 plastic scintillator tiles w. fiber+PMT • 2.8<  < 5.1; -1.7<  < -3.7 • Main L0 MinBias for p+p and A+A and centrality trigger A+A • Background (Beam-Gas) rejection, TRD wakeup • T0 (Beam-Beam Detector) Jyvæskyla+MEPhI,INR,Budker,Kurchatov • 2 arrays of 12 Cerenkov radiators + PM tubes • 4.5<  < 5.0; -2.9<  < -3.3 • Fast timing L0 signal (=50ps), online vertex determination • Main time reference, TRD wakeup, backup for MinBias trigger

  27. The first HV Distribution system for the TRD has been designed And developed in Athens. It has been successfully tested in Heidelberg ( Feb 2006) In order to achieve the TRD milestone for a full test of the first Supermodule At Heidelberg by the end of May this year our group has to construct 20 HV fully operated with CAN and Deetector Control System.

  28. Multiplicity Measurements 5+ measurements can give us the multiplicity: TPC:  n tracks ALICE ç coverage • ITS Pixel: • n clusters (in layer 1) • n tracklets

  29. Generated kinks inside TPC Reconstructed kinks inside TPC

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