a.litvinenko vblhep jinr Определение центральности столкновения...

A.Litvinenko VBLHEP JINR

Определение центральности столкновения ядер с использованием калориметра cпектаторов

в эксперименте MPD@NICA

A.Litvinenko, [email protected]

M.Golubeva, F.Guber, A.Ivashkin, A.Kurepin,INR, Moscow

A.Litvinenko, E.Litvinenko, A.Isupov, I.Migulina, V.Peresedov, JINR, Dubna


IntroductionSome definitionsSpectators

UrQMD generatorUrQMD generator LAQGSM generatorLAQGSM generator UrQMD - SHIELD - LAQGSMUrQMD - SHIELD - LAQGSM ConclusionsConclusions

OutlineOutline


NICA


MPD


Quasi-Classical pictureb – not observable observables b

Nuclear-Nuclear collisions

6

R

geo Rbdb2

0

2)2(2

Centrality classification

Value of impact parameter

Geometrical cross section

8%)(2 fm 42 b

In percent from the geometrical cross section

% 50 40Centrality

Corresponds to the region impact parameter

fm 9.5 (15)fm 0.63 )2( 4.0min Rb

fm 10.6 (15)fm 0.71 )2( 5.0max Rb

%) ( 2R

b

2R

b

(b

(b2

A

max

2

A

min

geo

max

geo

min

σσ

σσ ))

;)b(bdb)b(b

0

22 ππσ


1. (fm) b bb maxmin

2. Fraction from total cross-section

%) ( 2Rb

2Rb

2

A

max

2

A

min

3. Number of participant

…. ?

.partN

Impact parameter

%) ( 2Rb

2Rb

2

A

max

2

A

min

8



The importance of the centrality classification

elliptic flow scaling with space eccentricity short equlibration time

Space eccentricityElliptic flow

...)2cosv2cosv21(2

121

ddN

ε=A 2

2

v

Nuclear Physics A V757, No. 1-2 , p.184,2005


The importance of the centrality study

Jet Quenching – nuclear modification factor vs centrality

Nuclear Physics A V757, No. 1-2 , p.184,2005

Nuclear modification factor


The importance of the centrality study


Nucleon spectators (spectrum)

Yu.Bayukov et al ., YaF V.35, No. 4, p.960, (1982)

R.Ammarи et al., Pisma v JETF, V.94, No. 4, p.189, (1989)

nXPb

pXEm ~

nXC

X )p(backward Em


Spectator spectrum

)exp(-T/TC pd

dE 03

МэВ 10 - 5 T0

)Tmm-PP

exp(-C pd

dE

0N

2NFS

3

)σ

Θ•)

σ

)pp(•=

pd

σdE

Θp2

2

2

2b

3 2exp(-

2

-exp(-C

0.022 - 0.016 p

Tm GeV/c; 0.22 - 0.15

mTE

2b

0N

N

0bp


Front view of ZDC. The squares size is 5 x 5 cm x cm


ZDC@MPD geometrical efficiency

.)tot(N/)ZDC(N )ZDC( SS

central hole

out of ZDC

0.99 >)ZDC(ε

% 70 50 )d)

2exp(-

)d)2

exp(-

)ZDC(

0 2

2

r 2

2

ZDCint/L


Simulation Transport – Geant3 and Geant4, generates UrQMD and LAQGSM

framework MpdRoot


URQMD generator, Sqrt(S)=5 GeV

Total kinetic energy of all nucleonsdirected to ZDC

Optimistic results with UrQMD


UrQMD generator, Sqrt(S)=9 GeV

Total kinetic energy of all nucleonsdirected to ZDC

Optimistic results with UrQMD

0.782m- N

=A)S(

EΔ=ε

NN

ZDC


The accuracy of impact parameterdetermination for MC with UrQMD

% 18 E GeV 20 E GeV 114 E(b)

b fm 0.35 b ; fm 0

=δ;=Δ;=

=δ;=Δ=b

% 10 E GeV 38 E GeV 392 E(b)

% 13 b fm 0.67 b ; fm 5

=δ;=Δ;=

=δ;=Δ=b

C - N(b)

N(b) b

A

1 b ;

A

C-

N(b)1/ E NT E T E(b)

N(b)1/ N N N C;

bb

=δ;)b(N=Δ)b(N

=b

=δ;•=Δ);b(N•=

=δ;=Δ+b•A=)b(N

% 7 E GeV 49 E GeV 673 E(b)

% 9 b fm 0.87 b ; fm 10

=δ;=Δ;=

=δ;=Δ=b

% 150 <<β;E

β=

E

EΔ

22

The centrality resolution evaluations √S=9 AGeVThe centrality resolution evaluations √S=9 AGeV


But

The NA49 collaboration. Eur. Phys. J., A2, 383, (1998)


LAQGSM high-energy event generatorLAQGSM high-energy event generator

But


LAQGSM generator, Sqrt(S)=5 GeV

Total kinetic energy of all nucleonsand fragments directed to ZDC

Taking into account spectator fragments


LAQGSM generator, Sqrt(S)=9 GeV


Taking into account spectator fragments


SHIELD event generator


LAQGSM, Sqrt(S)=5 GeV


URQMD, Sqrt(S)=5 GeV


At large impact parameters the most of spectator nucleons are bound in fragments.


Experimental data : the deposited energy for different types of spectators in dependence of

the centrality


All nucleons directed to the hole of ZDC (rectangle 10x10cm2)

0 % - 60 % 60 % - 80 % 80 % - 100 %

mrad 100.3 -3 30.=rad•~θ


At large impact parameters the most of spectator nucleons are bound in fragments.


Experimental data : the deposited energy for different types of spectators in dependence of

the centrality

33

The centrality resolution evaluations The centrality resolution evaluations √S=9 AGeV√S=9 AGeV

Kinetic energy of all spectators directed to solid angle 5º

The centrality resolution evaluations √S=9 AGeVThe centrality resolution evaluations √S=9 AGeV


The centrality determination: ZDC (energy) + number of charged barrel

tracks


UrQMD - SHIELD - LAQGSM

b < 3 фм (0 – 4 %)



3 фм < b < 9.5 фм (4 – 40 %)



9.5 фм < b (40 – 100 %)


Centrality determination in some experiment

y=0 y=3y>6

STARPHENIXNA49

NA49 ZDC Only

STAR TPC only

PHENIX BBC & ZDC


Conclusions

• The SHIELD and LAQGSM could be used for NICA/MPD simulations under mpdroot.

• The SHIELD and LAQGSM angular distributions of the spectators differ from URQMD picture.

• The experimental study of the spectator distributions and calorimeter resolution have to be performed on the extracted beam of NUCLOTRON-M at the fixed target.


Conclusions

•Работа выполнена при поддержке грантов РФФИ

10-02-01036-а

11-02-01026-а


Backup slidesBackup slides


Fast evaluations: the movement of spectators at NICA/MPD

bpXY

Z

T 1 B

QB0.3Ap

- Ap

zQB0.3cos

QB0.3Ap

)z(y

ApzQB0.3

sinQB0.3Ap

)z(x

T

z

T

z

T

ApzQB0.3

cos12QB0.3Ap

yx )z,B(z

T22

Ap

zQBz

p

pzB

Ap

zQB

zz

T

z

0.3

2

1 ; ),( 0.2

0.3

The conclusion:Magnetic field of MPD will not change the polar angles for spectators at ZDC position it will only slightly changes the azimutal angles

06 zT p/p



C.E.Aguilar et al., Brazilian Journal of Physics, V.34,No.1,p.319,(2004)


Calorimeter No.1


Linearity

Resolution

Longitudinal distribution


Calorimeter No.1


CONCLUSION


Пространственное разрешение


)c/GeV(Pz )c/GeV(Pz

)c/GeV(Pz)c/GeV(Pz

partN

)c/GeV(Px

)GeV(EZDC

partN

partN

ZDC


ZDC + Multiplicity

1000 Min Bias

chN


ZDC + Multiplicity

1000 Min Bias

chN

chN chN

chN


PHENIX

ZDC + BBC


NA49

VCAL (ZDC)

65

TIME = 0 fm/c, 0.7

66

TIME = 1 fm/c, 0.6

67

TIME = 2 fm/c, 0.5

68

TIME = 3 fm/c, 0.3

a.litvinenko vblhep jinr Определение центральности столкновения...

Documents