grid and f analysis in pp

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)


2

pT spectrum corrected for efficiency


(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


4

all pT

ɸ properties : (mass, width)


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)


6 realistic analysisBackground fit

78M ppMB events

ɸ properties : (mass, width)(Voigtian = Breit-Wigner gaussian)


7 realistic analysisBackground fit

5.6M ppMB events

pT spectrum for TOF time resolution of 130 ps


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)


9

90% of background (same sign kaons) subtructed

No background subtruction

Preparation of publication of an early physics paper


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


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


12

Nevents = 26726Nevents

SPD = 7367Nevents

T0-TOF = 478Ntracks

TOF = 2123PRELIMINARY

With time slewing correction

TOF resolution and abundancies


13

Nevents = 26726Nevents

SPD = 7367Nevents

TOF-T0 = 478Ntracks

TOF = 2123

PRELIMINARY

Event time (T0-TOF) efficiency


14

Nev

ents

T0-TOF


15

Run 1

Run 2

Nev

ents

Backup


16

PID Efficiency (Contamination)


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)


18 con l’effetto dovuto alBackground subtraction

74M ppMB events

Sovrastima dovuta a fondo residuo (2-3%)


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

grid and f analysis in pp

Documents

noferini grid

psalice tof general

ptalice tof general

resonances properties

time of flight detector

resonances analysis

study of resonances

resonancesmass resolution