V.I. Kolesnikov on behalf of the MPD-TOF group

V.I. Kolesnikov on behalf of the MPD-TOF group

Round Table Discussion JINR, Dubna9-12 September 2009

Study of charged hadronStudy of charged hadron production in HI collisionsproduction in HI collisions with the MPD-TOF detectorwith the MPD-TOF detector

Outline

Physics motivation The apparatus and the MPD Time Of Flight detector Progress in TOF hardware development - RPC prototyping, tests

Particle Identification in the MPD experiment (TOF)

Identified hadron (, K, p) pt-spectra in Au+Au collisions

Summary

V.I. Kolesnikov Round Table Discussion, 11 September 2009 2

NA49: anomalies in hadron production:

“Kink” – steeping in relative pion (entropy) production

“Horn” – sharp maximum in the strangeness-to-entropy ratio in the transition region

“Step” - plateau in the excitation function of the apparent temperature of hadrons

Evidence for deconfinement in A+A collisions

NA45: excess indilepton massspectra

Also wealth of RHIC dataAlso wealth of RHIC data(jet quenching, constituent(jet quenching, constituentquark scaling for v2, B/M-ratio)quark scaling for v2, B/M-ratio)

NA50: anomalousJ/suppressionIn central A+A,thermal radiation


Important to establish the onset of the observed signatures Important to establish the onset of the observed signatures motivation motivation for next generation of HI experiments!for next generation of HI experiments!

Comprehensive study of the phase diagram of strongly interacting matter:

Studying the phase boundary, nature of the transition and properties of the transition region

Search for the Critical End Point, signals of the Chiral Symmetry Restoration and P (CP) violation

Theoretically, little known about low T - high b range of the QCD phase diagram – new measurements will encourage theory to go further.

Studying heavy ion collisions at NICA

Requirements to experimental facility: High luminosity access to many rare probes Large homogenous acceptance of the detector and.. ..and good tracking and particle identification capability total event reconstruction


• Early stage conditions, partonic dynamics, energy and baryon transportEarly stage conditions, partonic dynamics, energy and baryon transport net baryons, flownet baryons, flow

• Thermodynamic properties, test for equilibrium, (T-Thermodynamic properties, test for equilibrium, (T-BB)-mapping)-mapping

inclusive hadron spectra, multiplicities and particle ratiosinclusive hadron spectra, multiplicities and particle ratios

• EOS, transverse and longitudinal expansion, collective phenomena,EOS, transverse and longitudinal expansion, collective phenomena, space-time evolutionspace-time evolution spectra, HBT, cluster yields and coalescencespectra, HBT, cluster yields and coalescence

• Signals for phase transitionSignals for phase transition strangeness-to-entropy (K/strangeness-to-entropy (K/) ratio, slopes) ratio, slopes

• Critical phenomena during nuclear matter evolutionCritical phenomena during nuclear matter evolution particle ratio and net-baryon number fluctuationsparticle ratio and net-baryon number fluctuations

• Related topics (event characterization) centrality and event plane determination with hadron multiplicity

Hadron probesHadron probesFor studying fundamental properties of the Hot QCD MatterFor studying fundamental properties of the Hot QCD Matter ((objectivesobjectives//observablesobservables))


The Apparatus


MPD Detector

•Homogenous acceptance (totalcoverage)• Event rate up to 7.103 Hz• Excellent PID capabilities

TrackingTPC in a 0.5 T magnet + silicon vertex IT

PIDCharged: TOF (p<2.5 GeV/c) + dE/dx (p<0.5 GeV/c)Neutral: ECAL

Event characterization& triggeringCentrality: ZDC, BBSTiming: FD


MPD Performance


Acceptance (B=0.5 T):Full azimuthalIT (||<2.5)TPC (||<2)TOF (||<3)ECAL (||<1.2)BBC (1.5<||<4.2)Forward (2<||<4)ZDC (||>3)

TPC (dE/dx):/K ~0.6 GeV/c, (,K)/p ~1.0 GeV/c

TOF:TOF:/K ~ 1.5 GeV/c/K ~ 1.5 GeV/c((,K)/p ~ 3 GeV/c,K)/p ~ 3 GeV/c

MPD TOF detector

design RPC prototyping


S. GolovatyukS. Golovatyuk

The MPD TOF detector

Dimensions, coverage: length – 5 m inner radius - 1.2 m, outer radius - 1.4 m coverage - ||<1.4

Granularity: 12 sectors in 55 RPC modules (62x7 cm2) along z 48 2.5x3.5 cm2 pads in each module # of readout channels – 31700 geom. efficiency - 95% thickness X/X0 ~ 20%

Resistive Plate Chambers :

• widely used (STAR, ALICE, HADES, CBM)• intrinsic time resolution up to 60 ps• functional in magnetic fields, 100% efficient up to fluxes ~ 103 cm-2s-1


TOF barrel

TOF endcap(s)

Dimensions, coverage: outer diameter - 2.5 m inner diameter - 0.4 m coverage 1.4<||<3

Granularity: 28 RPC modules (53,37,21x100,80,100 cm2) 2640 4x4 cm2 pads in total

geometrical efficiency - 95%thickness – X/X0 ~ 20%


Final optimization of the TOF set-up is an ongoing task of MC studiesFinal optimization of the TOF set-up is an ongoing task of MC studies

Double stack (10 gaps) RPC, read-out pads 2.5 х 3.5 cm2

An RPC prototypeactive area 7 x 14 cm2

TOF RPC prototyping


1

2

3

4

1 – MRPC, 2 – trigger scintillators, 3 – electronics, 4 - gas system.


TOF RPC prototyping (2)

Charge distribution for a 10 gaps RPC prototype. U= 11 kV. Gas mixture: 90% C2H2F4 + 5% i-C4H10 + 5% SF6

ADC bins

Particle identification & Hadron spectra


V. KolesnikovV. KolesnikovS. LobastovS. Lobastov

Hadron transverse spectra in A+A

40 AGeV

5

Focusing on K/Focusing on K/• Experimental uncertainties (NA49): 8-10%Experimental uncertainties (NA49): 8-10%• Thermal models are advancing andThermal models are advancing and approaching the Horn approaching the Horn K/K/- ratio to be measured with 5% precision- ratio to be measured with 5% precision Feasible?Feasible?


• As many as possible hadron species• Apparent temperature (<pt>), transverse flow (T,) using blast wave fits• Integrated distributions as an input for statistical models (fits for (T-B mapping))

Important! Precise measurement of the spectral shapes at low pt (pt<0.3 GeV/c) How well can we (MPD) reproduce shapes?

NA49NA49


K/K/-ratio (data versus thermal model predictions)-ratio (data versus thermal model predictions)

[A. Andronic et al., Phys. Lett. B 673 (2009) 142]

MPD SimulationMPD Simulation & reconstructionMpdRoot (based on the FairRoot framework)


Inside look at a HI collisionMPD , Au+Au, 9 GeV

MC studies were carried out with the aim:MC studies were carried out with the aim: To test the simulation and reconstructionTo test the simulation and reconstruction To develop the methods and tools for hadron PIDTo develop the methods and tools for hadron PID and producing of inclusive spectraand producing of inclusive spectra

MPD analysis chain Hadron spectra & yelds

UrQMDUrQMD

TransportTransportGEANTGEANT

Track Track reconstructionreconstruction

TOF matchingTOF matching

Particle ID,Particle ID,Hadron spectraHadron spectra

1.5k Au+Au, 9 GeV, 3-6 fm1.5k Au+Au, 9 GeV, 3-6 fm

Geometry, physicsGeometry, physics

Kalman filterKalman filter

Corrections: efficiency, decay, etc..Corrections: efficiency, decay, etc..Track selectionTrack selection


No detailed simulationNo detailed simulation which includes allwhich includes all sub-detectorsub-detector characteristicscharacteristics

TOF phase-space coverage


BarrelBarrel

Barrel + endcapBarrel + endcap

• 103 UrQMD (Au+Au) events • Vertex_z = 0.0 cm

• Magnetic field = 0.5 T

|| < 1.4, pt=[0.1..2] GeVc – barrel|| < 2.6, pt=[0.1..2] GeVc – barrel+endcap

• Low-pLow-ptt part of the acceptance is part of the acceptance is

of importance for spectra of pionsof importance for spectra of pions

• Better coverage at low pBetter coverage at low ptt

for smaller B valuesfor smaller B values

• B=0.2 T seems a better choice B=0.2 T seems a better choice for ‘yield & ratio’ measurementsfor ‘yield & ratio’ measurements

Zoom at low-pZoom at low-ptt range range (magnetic field optimization)(magnetic field optimization)


TPC-TOF track matching

Reconstructed in TPC tracks propagated in the magnetic field to the TOF Kalman filter method used to account for multiply scattering Fast searching algorithm (STL-based) for the most probable pad crossing with the track extrapolation


Efficiency ~ 90%Efficiency ~ 90%


TOF PID capability

mm22=p=p22(c(c22TT22/L/L2 2 - 1)- 1)

T=100 ps, T=100 ps, p/p, p/p, L(p) – from MC trackL(p) – from MC track reconstruction. reconstruction.

~ 2~ 2 /K separation @ 1.3-1.5 GeV/c/K separation @ 1.3-1.5 GeV/c

No vertex and IT reconstruction in theNo vertex and IT reconstruction in thecurrent analysis, zero capability forcurrent analysis, zero capability forrejecting secondaries ..rejecting secondaries ..No secondaries – “ideal” conditionsNo secondaries – “ideal” conditions

PID method for hadron selectionPID method for hadron selection

• Simple contour cuts usedSimple contour cuts used for selection: nfor selection: n cut + max. cut + max. contamination 5%contamination 5%

• Parameters from massParameters from mass22

3 Gauss fits in momentum3 Gauss fits in momentum binsbins

• Correction for losses/misIDCorrection for losses/misID from the fitsfrom the fits


Au+AuAu+Au


Required corrections to raw yields (first version):Required corrections to raw yields (first version): efficiency (TOF matching)efficiency (TOF matching) geometrical acceptance, decaygeometrical acceptance, decay Particle IDParticle ID track reconstruction efficiencytrack reconstruction efficiency feeddown from hyperon decaysfeeddown from hyperon decays syst. error estimatessyst. error estimates

PurityPurity & & contaminationcontamination with the contour cutwith the contour cut

CorrectionsCorrections

Hadron spectra in Au+AuHadron spectra in Au+Au (MPD TOF, |y|<0.5, B=0.2 T(MPD TOF, |y|<0.5, B=0.2 T))

• First (prelim.) spectra lookFirst (prelim.) spectra look reasonablereasonable

• Low-pt efficiency problemLow-pt efficiency problem for K, p?for K, p?

• More detailed MC neededMore detailed MC needed


Lines: UrQMD inputLines: UrQMD input

SummarySummary

Extensive preparation of the NICA Heavy Ion program shows that the MPD detector has excellent opportunities for making a comprehensive exploration of the QCD phase diagram in the NICA energy range.

First studies on the performances of the MPD for measurement of hadron production in Au+Au has been done.

The hadron spectra reconstruction in the current production chain is feasible, but we have to understand better some thing concerning low-pt efficiency corrections

Next steps: try to implement this analysis in more realistic environment (vertex fiitting, IT reconstruction, dE/dx PID + all secondaries).

Ongoing activities enable further detector improvement and software tools development.


27MPD Collaboration

Thank youThank you

for your attention!for your attention!

L= 1·1027 cm-2 s-1 , 6.8 b for AuAu6 kHz minimum-bias rate (90%)

300 Hz central (5%)

A data set of 106 events is

sufficient for spectra & yields analysis

So, the statistical uncertainty is not a problem


Documents

V.I. Kolesnikov on behalf of the MPD-TOF group