Prospettive sulla fisica pp a LHC con ALICE

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Prospettive sulla fisica pp a LHC con ALICE
2 convegno nazionale sulla fisica di ALICE
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Fisica soft Charm e beauty (cenno, v.
Federico) Jets e fotoni (cenno, v.
Nicola) Trigger Aspetti organizzativi
Luciano RAMELLO Universita del Piemonte
Orientale e INFN, Alessandria
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Machine time scale (J-P Revol scenario)

• T0 ( 1st of July 2007 as of today)
• One month to get the machine ready for beams (T0
  1 month)
• Three months to commission the machine with beams
  (T0 4 months) gt possibility for ALICE to
  collect the first pp data sample for first paper!
• One month of rather stable operations,
  interleaved with machine development with 43 and
  156 bunches, with the possibility of collisions
  for physics during nights ( 20 shifts of 10
  hours each L 1030cm2s1) (T0 5 months)gt
  possibility for ALICE to collect the first large
  pp data sample!
• Perhaps first Pb-Pb collisions.
• Shutdown (T0 8 to 9 months) today machine
  people talk about 3 to 4 months. It will depend
  on requirements by experiments. If T0 1st of
  July, start of shutdown will coincide with the
  Christmas holidays.

Stable beams
Preparation
First collisions.
Shutdown 3 to 4 months?
July
Nov.
Feb.
Mar
Aug.
Sept.
Oct.
Dec.
Jan.
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Fisica soft
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Soft Physics studies for the first data
taking with ALICE

• Using as a benchmark the studies published on PPR
  Vol.2,
• we started to review the topics from which we can
  expect results
• In the first data taking, assuming the two
  proposed scenarios
• 1) analysis of a small sample of 104 MB events
• 2) analysis of a sample collected in 200 h (200
  h 7.2 105 s)
• If we assume to collect data at the max. DAQ
  rate of 100 Hz
• in 200 h we will collect a sample of 7.2
  107 MB events
• We will present expectations for the following
  physics issues
• Global event properties
• Identified hadron spectra
• Strange particle identification
• Resonances
• HBT and Event by Event physics correlations and
  
• fluctuations (nothing shown today)

CERN, March 10, 2006 Meeting on Preparation for
first physics with ALICE
Marco Monteno for the PWG2 Soft Physics Working
Group
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Expected multiplicities at the LHC
in pp collisions
LHC
C. Jorgensen
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Global event properties in pp collisions
M. Monteno, T. Virgili C. Jørgensen

• Day-1 physics with 104 pp events
• Multiplicity distribution of charged particles
  in a given ? range
• Central pseudorapidity range (TPC, ITS-Pixels
  tracklets)
• Forward pseudorapidity range using FMD hits
• dN/d? distribution of charged particles for
  central and forward
• pseudorapidity regions
• pT spectra for charged particles in a given ?
  range
• This can be done withou
• Distributions from the first data at 900 GeV can
  be compared with all the
• past collider results!!

60000 Pythia pp events (PPR Vol.2 Chap.6.1)
Silicon Pixel Detector (tracklets)
Stat. limit for 109 pp pT 80 GeV
generated
Rec/gen 90 for pT gt 1 GeV gt 70 for 0.2
lt pT lt 1 GeV
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Global event properties in pp collisions
Non Single Diffractive events
hlt0.9
pT reach
Number of charged tracks above a given pTmin -gt
statistical limit (100 counts)
pTmax gt 50 GeV/c for 108 NSD pp events (in 200
h)
hlt0.9
Multiplicity reach
Number of events above a given multiplicity M
Mmax 140 for 108 NSD pp events
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Global event properties in pp collisions
Other possible fast analyses
ltpTgt vs multiplicity
Mean transverse momentum distribution
Mean 0.6 GeV/c
Next step

• pT spectra of identified pion, kaons and
  protons within central rapidity
• range (needs for calibration of ITS, TPC,
  TOF, HMPID.)
• multiplicity and pseudorapidity distributions of
  pions, kaons and protons
• ltpTgt vs multiplicity of pions, kaons, proton (as
  at Tevatron)

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ALICE pseudorapidity coveragefor multiplicity
measurements

• Different multiplicity measurement techniques
• CLUSTERS on innermost ITS layers (Silicon Pixels)
• TRACKLETS with 2 innemost layers of ITS (Silicon
  Pixels)
• FULL TRACKING (ITSTPC)
• ENERGY DEPOSITION in the pads of Forward
  Multiplicity Detector (FMD)

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dN/dh reconstruction
T. Virgili
p-p events
Due contributi sono ancora mancanti, relativi
alla selezione degli eventi (solo per p-p) e la
sottrazione del background. Il lavoro è in
progress, in collaborazione con Domenico Elia.
Ancora mancante un confronto completo con la
molteplicità misurata con le tracce (TPCITS).
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Charged Multiplicity measurement in pp
(Claus Jorgensen) 5 measurements can give us
the multiplicity
TPC ? n tracks

• ITS Pixel
• n clusters (in layer 1)
• n tracklets

• FMD
• naïve method (n hits)
• poisson method

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Spectra Corrections (C.J.)
C. Jørgensen
We have N events N tracks. We want N
collisions N primary charged particles.

• N tracks to N particles
• Track to vertex cut efficiency
• Geometrical acceptance
• Detector/reco. efficiencies
• Decay and feed-down
• Trigger bias

• N events to N collisions
• MB trigger efficiency
• Vertex reco. efficiency
• Beam-gas halo

(ALICE-INT-2005-025)
) Including decay products from strong and
electromagnetic decay, excluding products of
weak-decay and secondary interactions.
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Making spectra (C.J.)
Procedure ? loop over events ? loop over
tracks ? select good tracks (vtx ? cut)
? fill histogram weighted by
1/(e(?,pT) ? 2p ? pT ? dpT) ? normalize hist by
1/(ßNevents?d?)
as function of pT
e(?,pT) is the correction map. ß is the
correction for trigger and vertex reconstruction
efficiency (not included).
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Beam gas interaction - Pseudo-rapidity
distribution
Rate in TPC 0.1 Hz ?
TPC
charged
m-Spectrometer
protons
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Conclusion on TPC Multiplicity measurement
(Marian Ivanov)

• The crucial parameters which affects the results
  of multiplicity measurement
• Tracking efficiency
• DCA resolution
• Expected systematic effect before applying the
  alignment and calibration on the level of 4
  sigma
• Affects mainly DCA to primary vertex measurement
• Has to be taken into account in analysis
• Decrease of efficiency (in comparison with ideal
  situation) not expected
• We should put an effort to obtain the first TPC
  calibration and alignment before the first
  production run, using the cosmic, laser and beam
  gas interactions

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Effective energy in pp using the ZDC
F. Noferini
ZDCP range
ZDCN range
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Identified Hadron pT Spectra Ratios
Understand production mechanisms for different
hadron species in pp collisions
PYTHIA 6.3
G.Paic, E. Cuautle (Mexico City)
106 pp event statistics
The systematics of baryon production are
reflected in the ratio of proton to pion
production. Three different mechanisms of baryon
production, implemented in PYTHIA have been
investigated. The simulations (PPR Vol.2
6.2.2.3) show that with 106 events it will be
already possible perform this study (in the range
where ALICE can provide good PID). Therefore this
analysis can be done on the first 200 h data
sample
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Estimates of ? signal in the first ALICE run
(1)
?
Statistics 104 MB events !!!
132 ? reconstructed
L. Gaudichet
Conclusion YES ! We would have a small signal of
? in 104 events. From that we could probably
publish a yield (though we would have big error
bars).
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Estimates of ? signal in the first ALICE run
(2)
L. Gaudichet
Statistics 7 107 MB events !!!
?
926839 ? reconstructed
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? and ? signals in the first ALICE run (200 h
)
18950 X reconstructed
X
Statistics 7 107 MB events !!!
190 ? reconstructed
L. Gaudichet
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Identification of K, K- via their kink topology
K mn
pp collisions
pp collisions
Limit of combined PID
These are results published in PPR Vol.2, with a
statistics of 109 events. With 108 events
collected during the first 200h run, situation
should be similar, with a slight decrease in the
maximum pT reach.
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Resonances

• Studies not feasible with 104 events
• Feasibility with the first 200 h data sample
  statistics !
• Generally, having a correct measurement of
  resonance yields
• and pT spectra will take more time than most of
  the others observables
• need to well describe the background
• need to have consistent results between
  hadronic decay
• channels and leptonic ones,

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Resonances ? and K
K(892) K p
f (1020) KK-
2x106 pp PYTHIA events
2 x 105 pp PYTHIA events
Perfect PID
A.Pulvirenti
D. Tapia Takaki
No PID

• Total number of reconstructed K
• anti-K in the analyzed sample 4000

Mean 892.6 2.1 MeV/c2 FWHM 49 6 MeV/c2
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Resonances ?(1520)
F. Blanco
?(1520) K p
6 x 104 pp PYTHIA events Simulated Yield 2
Yield foreseen at LHC decay forced to Kp

• Total number of reconstructed ?(1520)
• in the analyzed sample 400

S/B (2s) 0.18 S/v(SB ) 8.2
m 1.521 0.001 G 0.018 0.06
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Resonances ? in the ?? channel
R. Platt
Background shape is very complicated
Not shown results in the leptonic channel (not
yet mature)
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Resonances ? in the ?? channel, contd
R. Platt
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What do we expect to see from pion HBT with pp _at_
ALICE?
Tom Humanic
Pion HBT with pp _at_ STAR Zbigniew Chajecki QM05
Jet model for HBT with pp _at_ FNAL/LHC Guy Paic
and Piotr Skowronski J. Phys. G Nucl. Part..
Phys. 31 (2005)
jet
p
p
jet
Finds R increases as dN/dy increases, as seen In
FNAL data
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Charm e beauty (cenno)
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PWG3 summary (G. Martinez, March 2006)

• First Physics during the first pp run (Nov. 2007)
• First, 10000 events minimum bias trigger pp
  (efficiency close to 100)
• Then, 20 shift of 10 hours at Luminosity1030
  cm-2 s-1 (Revol's Scenario) 107 minimum bias pp
  events and 109 muon triggers
• We focused on
• Analysis code development PWG directories in
  ALICE CVS repository, Background subtraction
  code, Realistic pp production simulation,
  raw-data, calibration, reconstruction, ESD (AOD)
  analysis.
• First physics to be done.
• New Physics studies not included in the PPR that
  could be done during the 1st physics run J/Psi
  polarisation, W boson detection, single beauty
  electrons in pp, ...

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PWG3 List of physics analyses during run1

• run1_pp_charm_kpi
• run1_pp_charm_kpipi
• pp_charm_kkstar
• pp_charm_phipi
• run1_pp_beauty_e-single
• run1_pp_beauty_mu-single
• run_1_pp_beauty_mumu
• pp_beauty_mumumu
• run1_pp_W_mu
• pp_Z_mumu

• pp_charmonia_ee
• run1_pp_charmonia_mumu
• pp_charmonia-pola_ee
• run1_pp_jpsi-pola_mumu
• pp_bottomonia_ee
• pp_bottomonia_mumu
• pp_bottomonia-pola_ee
• pp_bottomonia-pola_mumu
• pp_beauty_emu
• pp_charmonia-fromB_ee

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D0? K-p results (II)
inner bars stat. errors outer bars stat. ?
pt-dep. syst. not shown 9 (Pb-Pb), 5 (pp,
p-Pb) normalization errors
1 year at nominal luminosity (107 central Pb-Pb
events, 109 pp events) 1 year with 1month of
p-Pb running (108 p-Pb events)

• Down to pt 0 in pp and p-Pb (1 GeV/c in Pb-Pb)
• important to go to low pT for charm cross-section
  measurement

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Jets e fotoni (cenno)
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First LHC pp run (Y. Schutz, March 2006)

• One (1) PHOS module and 20 shifts
• Isolation efficiency 70
• Systematic errors 16 25

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Early pp running (Y. Schutz, March 2006)

• Number of jets
• For 104 events 100 Jets gt 20 GeV
• For 107 events 100 Jets gt 100 GeV (untriggered)
• Serious analysis for gt 108 events
• As statistics and pT-reach increase
• Determine fake-track rate
• Determine reconstruction efficiency and
  pT-resolultion
• Optimise quality cuts
• Understand influence of dead-zones and optimise
  fiducial cuts
• Analysis Topics
• Jet fragmentation
• Multiplicities, pT-Spectra
• kT Spectra and jet-shape
• Identified particles
• Study of underlying event properties

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Trigger
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Trigger inputs
6.4 µs
R. Lietava / Birmingham
1.2 µs
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L0 Trigger Inputs
Order is important any logical function from
first 4 inputs
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pp Physics Triggers
R. Lietava / Birmingham

• MB1 ((V0.MB) (Pixels) (T0)) not(V0.BG)
• MB2 V0.MBPixelsnot(V0.BG)
• MuonX MB MuonX
• PHOS MB MB PHOS.MB

• Comments
• - MB L0 function
• V0.MB V0.OR
• V0.BG (V0.BGA V0.BGC) input
• - 3 clusters for physics All, central, muons

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D. Elia, T. Virgili
SPD Fast-OR simulation What has been done

• Code implementation in AliRoot (contd)
• recent work
• updated trigger class (in collaboration with C.
  Jorgensen)
• two different methods implemented
• MultiplicityTrigger() providing 2 basic inputs
• ? ITS_SPD_GFO_L0 (for min-bias p-p)
• ? ITS_SPD_HMUL_L0 (for high-multiplicity
  p-p)
• GeometricalTrigger() left for additional inputs
  (not activated)
• based on topological correlation between
  Fast-ORs
• e.g. ? trigger for HMPID in p-p
• ? trigger for ultra-peripheral in Pb-Pb

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D. Elia, T. Virgili
SPD Fast-OR simulation What we plan to do

• Further simulation studies
• trigger for high multiplicity in p-p
• basic physics motivation
• enhance fraction of high multiplicity p-p
  collisions for pt studies,
• strangeness content etc (and comparisons with
  Pb-Pb)
• sample of pp minimum bias generated on the Bari
  PC-farm
• AliRoot v4-03-06, Config PYTHIA 6.214, kPyMb
  process
• total statitics already available 50K events
• analysis just started !
• trigger for HMPID in p-p
• triggers for Pb-Pb (ultra-peripheral,
  centrality?)

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Aspetti organizzativi
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ALICE Commissioning Task Force

• Detector commissioning
• Commissioning of detector hardware
  infrastructure
• Coordinated by C. Fabjan and H. Taureg
• Tools, procedures (in between hardware and
  software)
• Different tasks which are usually omitted
• Complicated interplay between different groups,
  project
• From Detectors, DAQ, Controls and Offline
• Coordinated by E. Nappi and K. Safarik
• Preparation for first physics
• Coordinated by J.-P.Revol

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Activities of Commissioning Task Force

• Standalone, can be done independently by
  dedicated person(s)
• Magnetic field (R. Shahoyan)
• Luminosity (T. Nayak )
• Trigger
• Centrally done, where input from detector
  projects needed, however done in central group
• Alignment (overall), Raw Data reading (real
  data)
• Done basically in detector projects, with a
  coordinating person to insure that the same
  framework and tools are used
• Calibration, Alignment (one detector)
• Reconstruction (different scenari)
• Tools for event analysis (from ESD)

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Preparation for First Physics

• Tasks (coord. by J.-P. Revol)
• Definition of vertex primary secondary
• Definition of primary track secondary track
• Strategy for correction
• Efficiency corrections
• Acceptance corrections
• Normalization for pp (inelastic vs.
  non-diffractive)

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Organizzazione interna PWG2

• Coordinamento software di analisi
• Stranezza - B. Hippolyte
• Risonanze A. Badala / A. Pulvirenti
• Caratteristiche globali E. Scomparin / C.
  Oppedisano
• Flow R. Snellings
• HBT M. Lisa
• EbyE P. Christakoglou
• Prime azioni
• raccolta del codice usato per il PPR
• uso di AliSelector, AliSelectorRL (dir. PWG0)
  per implementazione analisi distribuita
• P. Christakoglou end responsible per controllo
  del codice sottomesso dai coordinatori
• eventi pre-PDC06 in /castor/cern.ch/user/p/phrist
  ov/pp2006/
• pagina per documentazione, segnalazone BUGs
  etc. https//savannah.cern.ch/projects/aliroot
  /

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Conclusioni / Prospettive

• Studio dei canali di fisica accessibili con il
  primo run protone-protone a buon punto
• Sono stati identificate le analisi veloci che
  non richiedono grande precisione di calibrazione
  o allineamento
• E il momento di consolidare il codice e renderlo
  compatibile con lanalisi distribuita degli ESD
• Da completare procedure di calibrazione e
  allineamento, studi di trigger,

agli organizzatori locali GRAZIE !!!