Physics from

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Physics from PMD in ALICE PPR

• OUTLINE
• Chapter 3
• PMD design layout parameters
• Chapter 5
• PMD performance
• Chapter 6
• 1. Event Characterization
• 4. Flow
• 6. Quarkonia production
• Event-by-event physics
• Jets in forward region

Tapan Nayak PPR Meeting, Feb 6-7, 2003
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PMD
V0
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PMD Split Position
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PMD Parameters
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Chapter 6.1 Centrality Estimation using PMD
We define ET_PMD ? dE Sin (?) The
sum run over all the cells and dE is energy loss
in a given cell.
Simulation using HIJING Aliroot
Total trans. Energy vs Npart
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Impact Parameter Resolution

• Resolution comparable
• to ZDC
• We are now studying
• this using different
• pseudo-rapidity region
• of PMD
• A simple EDEP sum
• without the sin(theta)
• gives better results. This
• can be easy to implement
• in hardware.

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Chapter 6.4 Flow
By using eff, purity and decay effect the
photon data is prperly understood with respect to
charged particles.
Chapter 6.6 Quarkonia Production already
included.
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Chapter 6.9 Event-by-Event Fluctuations

• J.D. Bjorken 1992
• Rajagopal Wilczek 1993

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MEASURES OF FLUCTUATIONS
Space-time evolution of fluctuations are
important!
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158.A GeV PbPb at SPS
STATISTICAL DYNAMICAL
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Multiplicity Fluctuation
Multiplicity distributions are GAUSSIANS
for narrow bins in centrality. The physics
(statistical dynamical) is in the width of the
distribution. The amount of fluctuation
w s2/ lt N gt
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Centrality Selection
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Centrality Selection
Fluctuation in number of participants
Fluctuation should be measured and calculated
for narrow bins in centrality (2 cs bins ) such
that fluctuations in Npart is unity.
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Multiplicity Fluctuations for various centralities
Charged Particles
Peripheral
Central
Data agree fairly well with participant model
calculations
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Detector Acceptance
Mohanty, Phatak Mahapatra Int. J. Mod. Phys. A
17 (2002) 675

• A Simple Statistical Picture
• No. of particles produced in the collision m
• No. of particles accepted in the acceptance n
• Fraction of particles accepted f n/m
• The distribution of n follows a binomial
  distribution with
• mean mf variance mf(1-f).
• For a fixed m wn 1-f
• For m having an arbitrary distribution,
• wn 1 f f wm

By knowing the fluctuation in one acceptance, one
can get expected fluctuation in other
acceptances.
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Acceptance dependence of Multiplicity Fluctuations
Charged Particles
Dh 1
Dh 1/2
Data agree fairly well with participant model
calculations based on binomial sampling
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Fluctuations of Ch. particles vs. Photons To
search for DCC-like fluctuations

• Discrete Wavelet Analysis
• Correlation Analysis

Single event display gt Charged particles
superimposed on photons
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FLUCTUATIONS by using WAVELETS

• Analysis according to scale
• Number of bins 2j where j is the
  scale

Input function no. of Particles in a
bin Output Father function Coefficients (FFC)
at each j.
Provide a new mindset in Data Analysis.
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Ng vs. Nch FLUCTUATIONS

• Correlation Analysis

Localized phase fluctuations
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Formation of DCC upper limits
Global DCC
0-5 central

• Localized fluctuations decrease
• from central to peripheral.
• Upper limit for DCC-like
• localized fluctuations 3x10-3
• for central collisions.

1. Phys.Lett.B420169-179,1998 2.
Phys.Rev.C64011901,2001 3. nucl-ex/0206017, to
be published in PRC Krzywicki Serreau Phys.
Lett.B 448 (1999) 257
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DCC search Possibilities and Limitations
Mohanty, TN, Mahapatra, Viyogi nucl-ex/0211007

• Effect of Multiplicity
• lower statistical fluctuation in going
  from SPS to RHIC to LHC
• Effect of pi0 decay
• Effect of multiple DCC domains
• if the domains dont overlap it is still
  possible to look for these.
• Effect of detector limitations
• Charged particle contamination on photon
  measurement
• This is a serious limitation.
• Efficiency of photon detection
• Having pT information for charged particles
  only
• Helps in DCC search to a large extent.
• Having pT information for photons only
• This effect is not so appreciable because
  of pi0 decay effects.
• Having pT information for both charged
  particles and photons
• Signal to background in case DCC domain is
  photon excess or
• charged particle excess (photon excess has
  higher S/B)

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A Fluctuation probe for DCC
Mohanty, TN, Mahapatra Phys.Rev.C66044901,2002
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DCC search at RHIC and LHC

• Using charged particle and photon multiplicities
  
• classify events based on wavelet or correlation
  analysis as
• Normal events which are within 2 or 3 sigma from
  the mean
• Not-so-Normal events beyond that.

• For both set of events measure and compare the
  following proposed signals
• Kaon correlations (KsK vs KK-) Gavin,
  Kapusta
• Two-particle (HBT) correlations Gavin
• Dilepton signals
  Koch, Randrup, X-N Wang
• Omega and anti-Omega abundances Kapusta, SMH
  Wong
• Direct photons
  Charng et al. (Phys.Lett. B548 (2002) 175
• Pion Lasers
  Sinyukov Pratt
• DCC and Flow
  Mishra, Nandi, TN, Mohanty, Mahapatra

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Jets in forward region
50,000 PYTHIA jet events

• In the PMD acceptance
• Photons 346
• Pi_0 3374

Plenty of jets
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Energy of photons Pi-0s (Leading particle)
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Jet cross-section from D0
PRL 86 (2001) 1707
At LHC it should be larger
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What can we do in ALICE
Low-cost EM-calorimeter behind PMD (pp physics,
jets, E_t Flow.)
Five planes of 1cm lead 5mm Scintillator
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Preliminary results of simulation for the EMCAL
Energy deposition vs. incident energy
PMD cells vs. incident energy
Combine the Edep data and N-cell data to improve
resolution. (principal component analysis)
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Fluctuation not too large