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GRID and f analysis in pp. Francesco noferini ( infn cnaf – infn bologna ). ɸ analysis – the procedure. Efficiency estimate Particle Identification (PID) efficiency for kaons From kaons efficiency to ɸ efficiency Corrections Mass resolution from the tracking - PowerPoint PPT Presentation
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FRANCESCO NOFERINI(INFN CNAF – INFN BOLOGNA)
08/12/2009ALICE TOF - general meeting - F. Noferini - GRID and resonances
GRID and analysis in pp
1
ɸ analysis – the procedure
Efficiency estimate Particle Identification (PID) efficiency for kaons From kaons efficiency to ɸ efficiency
Corrections Mass resolution from the tracking Shift on the mass from the tracking
Systematics effects For tracking For PID
pT spectrumɸ properties : (mass, width)
08/12/2009ALICE TOF - general meeting - F. Noferini - GRID and resonances
2
pT spectrum corrected for efficiency
08/12/2009ALICE TOF - general meeting - F. Noferini - GRID and resonances
(II)3
5.6M ppMB at 10 TeV
78M ppMB at 10 TeV
Systematics evaluated with MC
TOF time resolution T0 resolution = 80 ps
Mass resolution from the tracking
08/12/2009ALICE TOF - general meeting - F. Noferini - GRID and resonances
4
all pT
ɸ properties : (mass, width)
08/12/2009ALICE TOF - general meeting - F. Noferini - GRID and resonances
574M ppMB events
Effect due to the acceptance (0.1%)
Integrated on the whole pT range
from Monte Carlo “truth”
ɸ properties : (mass, width)(Voigtian = Breit-Wigner gaussian)
08/12/2009ALICE TOF - general meeting - F. Noferini - GRID and resonances
6 realistic analysisBackground fit
78M ppMB events
ɸ properties : (mass, width)(Voigtian = Breit-Wigner gaussian)
08/12/2009ALICE TOF - general meeting - F. Noferini - GRID and resonances
7 realistic analysisBackground fit
5.6M ppMB events
pT spectrum for TOF time resolution of 130 ps
08/12/2009ALICE TOF - general meeting - F. Noferini - GRID and resonances
8
Reconstructed spectrum corrected for efficiecy.The current statistics is enough to perform such measurements in the first days of data acquistion.
•A sample of 1.8M ppMB (√s = 10 TeV) events was generated with PYTHIA6 and used to perform the following analyses.
The first analyses on real data (pp@900GeV) are confirming the hypoteses assumed in these studies (T0 resolution, TOF time resolution, …)
Presented at IFAE ‘09(Bari, 16th April)
TOF time resolution = 130 psLHC clock T0 resolution = 160 psTOF T0 resolution 50-60 ps
PbPb MB results (preliminary)
08/12/2009ALICE TOF - general meeting - F. Noferini - GRID and resonances
9
90% of background (same sign kaons) subtructed
No background subtruction
Preparation of publication of an early physics paper
08/12/2009ALICE TOF - general meeting - F. Noferini - GRID and resonances
10
Title Production of ɸ mesons in pp collision at √s = YY TeV
Abstract We present the study of ɸ resonances in the first pp(YY TeV) Minimum Bias collisions at the LHC with the ALICE detector. With a statistics of XX M of events we perform the reconstruction of the meson using the particle identification of the time of flight detector (TOF) in the kaon channel.
Structure • physical motivation for this study • central apparatus description + trigger (definition of MB)• tracking + identification techniques (TOF)• all efficiency corrections (including systematics)• results: spectra vs pt + mean&width for the resonance + ratio w.r.t. kaons• comparison with MC (Pythia, …)
Tables • selection parameters• yields vs. pT
• fit parameters (vs. pT)
Figures • invariant mass distribution• pT distribution
• ratio ɸ/K (vs. pT)
First look at ppMB data - √s = 900 GeV
08/12/2009ALICE TOF - general meeting - F. Noferini - GRID and resonances
11
Kp
1° day results
PRELIMINARY
results on7/12/2009
collisions on6/12/2009
T0 from TOF when available (if not from the machine clock, beam-beam < 160 ps)
Run:104068, 104070, 104157, 104159Nevents
SPD= 4222NT0-TOF=262
TOF resolution and abundancies
08/12/2009ALICE TOF - general meeting - F. Noferini - GRID and resonances
12
Nevents = 26726Nevents
SPD = 7367Nevents
T0-TOF = 478Ntracks
TOF = 2123PRELIMINARY
With time slewing correction
TOF resolution and abundancies
08/12/2009ALICE TOF - general meeting - F. Noferini - GRID and resonances
13
Nevents = 26726Nevents
SPD = 7367Nevents
TOF-T0 = 478Ntracks
TOF = 2123
PRELIMINARY
Event time (T0-TOF) efficiency
08/12/2009ALICE TOF - general meeting - F. Noferini - GRID and resonances
14
Nev
ents
T0-TOF
08/12/2009ALICE TOF - general meeting - F. Noferini - GRID and resonances
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Run 1
Run 2
Nev
ents
Backup
08/12/2009ALICE TOF - general meeting - F. Noferini - GRID and resonances
16
PID Efficiency (Contamination)
08/12/2009ALICE TOF - general meeting - F. Noferini - GRID and resonances
17
TOF resolution at 80 ps (final resolution)
TOF resolution at 130 ps (current resolution)
Efficiencycontamination
K p
Calcolo parametri della ɸ con risoluzione realistica (Voigtian = Breit-Wigner
gaussiana)
08/12/2009ALICE TOF - general meeting - F. Noferini - GRID and resonances
18 con l’effetto dovuto alBackground subtraction
74M ppMB events
Sovrastima dovuta a fondo residuo (2-3%)
08/12/2009ALICE TOF - general meeting - F. Noferini - GRID and resonances
19
03/12/2009 - giovedìMeeting TOF offline - F. Noferini - task performance
20ppMB 193k eventi PYTHIA
03/12/2009 - giovedìMeeting TOF offline - F. Noferini - task performance
21ppMB 193k eventi PYTHIA