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The centrality determination for the NICA/MPD using the LAQGSM generator. M.Baznat 1 , K.K.Gudima 1 , A.G.Litvinenko 2 , E.I.Litvinenko 2 1 Institute of Applied Physics, Academy of Science of Moldova, Moldova 2 JINR Dubna, Russia. The centrality determination – the observables:. - PowerPoint PPT Presentation
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The centrality determination The centrality determination for the NICA/MPDfor the NICA/MPD
using the LAQGSM generatorusing the LAQGSM generator
M.BaznatM.Baznat11, K.K.Gudima, K.K.Gudima11, , A.G.LitvinenkoA.G.Litvinenko22, , E.I.LitvinenkoE.I.Litvinenko22
1Institute of Applied Physics, Academy of Science of Moldova, Moldova2JINR Dubna, Russia
The centrality determination – the The centrality determination – the observables:observables:
• The number of particles produced in the region of rapidity close to zero
• The total energy of spectators
22
0
)2(2 RbdbR
geo
The centrality classification
Interval of impact parameter values
Geometrical cross section
fm 42 b
Interval given in percents from the geometrical cross section
% 50 40 Centrality corresponds to the region of the impact parameter:
fm 9.5 )2( 4.0min Rb
fm 10.6 )2( 5.0max Rb
Geometrical cross sectionfor the fixed impact parameter
0.4 )2/(b /)( 2minmin Rb geogeo
0.5 )2/(b /)( 2maxmax Rb geogeo
2
0
2)( bbdbbb
geo
The importance of the centrality study
elliptic flow scaling with space eccentricity
short equlibration time
Jet Quenching – nuclear modification factor vs centrality
At large impact parameters the most of spectator nucleons are bound in fragments.
The NA49 collaboration. Eur. Phys. J., A2, 383, (1998)
Experimental data : the deposited energy for different types of spectators in dependence of
the centrality
Obvious requirements to Obvious requirements to a Zero Degree Calorimeter a Zero Degree Calorimeter
aimed to determine the centralityaimed to determine the centrality
• The calorimeter should measure deposited energy of all types of the spectators: protons, neutrons and nuclear fragments;
• In order to reach good geometrical acceptance, the calorimeter sensitive areas should be placed to the positions where it is expected to catch the biggest part of the spectators energy;
• Detailed simulations with the transport of all types of spectators should be performed for each experiment individually taking into account the value and the configuration of magnetic field of the experiment;
• Event generator for such simulations should produce all types of the spectators with the reasonable yield, and transport code should be able to transport all types of the spectators.
ZDC for NICA/MPD (standard ZDC for NICA/MPD (standard geometry)geometry)
The technical design of ZDC for NICA/MPD proposed by the group of A.B.Kurepin (INR, Moscow)
ZDC consists from the modules 10x10x120cm3 (or 5x5x120cm3) . Each module consists of 60 lead-scintillator sandwiches 10x10cm2 with thicknesses 16 and 4mm. Main attention in the technical design was paid to the method of light readout from the scintillator tiles that should provide good efficiency and uniformity of light collection.
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
LAQGSM high-energy event generatorLAQGSM high-energy event generator
LAQGSM describes reactions induced by both particles and nuclei at incident energies up to about 1 TeV/nucleon, generally, as a three-stage process: IntraNuclear Cascade (INC), followed by pre-equilibrium emission of particles during the equilibration of the excited residual nuclei formed after theINC, followed by evaporation of particles from and/or fission of the compound nuclei.
LAQGSM intranuclear cascade model LAQGSM intranuclear cascade model
The latest improvements of LAQGSM codeThe latest improvements of LAQGSM code
LAQGSM related publicaitonsLAQGSM related publicaitons• LAQGSM03.03:
a) “CEM03.03 and LAQGSM03.03 Event Generators for the MCNP6, MCNPX, and MARS15 Transport Codes” S. G. Mashnik, K. K. Gudima, R. E. Prael, A. J. Sierk, M. I. Baznat, and N. V. Mokhov, LANL Report LA-UR-08-2931 ; E-print: arXiv:0805.0751v2 [nucl-th] 12 May 2008b) S. G. Mashnik et al., LANL Report LA-UR-07-6198; E-print: arXiv:0709.173v1 [nucl-th] 12 Sep 2007.c) K. K. Gudima and S. G. Mashnik, Proc. 11th Internat. Conf. on Nuclear Reaction Mechanisms, Varenna, Italy, June 12–16, 2006, edited by E. Gadioli (2006) pp. 525–534; E-print: nucl-th/0607007.
• LAQGSM03.01: S. G. Mashnik et al., LANL Report LA-UR-05-2686, Los Alamos (2005).
• LAQGSM: K. K. Gudima, S. G. Mashnik, A. J. Sierk, LANL Report LA-UR-01-6804, Los Alamos, 2001.
• Quark-Gluon String Model (QGSM): N. S. Amelin, K. K. Gudima, V. D. Toneev, Sov. J. Nucl. Phys. 51 (1990) 327–333; [Yad. Fiz. 51 (1990) 512–523]. Sov. J. Nucl. Phys. 51 (1990) 1093–1101; [Yad. Fiz. 51 (1990) 1730–1743]. Sov. J. Nucl. Phys. 52 (1990) 1722–178, [Yad. Fiz. 52 (1990) 272–282]
LAQGSM rapidity and pseudorapidityLAQGSM rapidity and pseudorapidity
sqrt(S)=9sqrt(S)=9
sqrt(S)=9sqrt(S)=9
sqrt(S)=5sqrt(S)=5
sqrt(S)=5sqrt(S)=5
URQMD and LAQGSM AuAu mbias data - URQMD and LAQGSM AuAu mbias data - theta:Ekin/Atheta:Ekin/A
URQMD sqrt(S)=9 GeV/u LAQGSM sqrt(S)=9 GeV/u
all nucleonsfree nucleons free nucleons +
fragments
pions pions + …
fragments
LAQGSM AuAu,LAQGSM AuAu, A:bA:b, , Pt/A:Pz/APt/A:Pz/A
Pt/
APz/Ab b
A
Are
st_o
f_pro
ject
ile
Sq
rt(S
)=5
Sq
rt(S
)=9
LAQGSM AuAu, sqrt(S)=9, Pt:Pz per LAQGSM AuAu, sqrt(S)=9, Pt:Pz per nucleonnucleon
URQMD generator, Sqrt(S)=5: all nucleons in 1000 events
Total kinetic energy of all nucleons for each URQMD event
Total kinetic energy of all nucleonsdirected to ZDC
Optimistic results with UrQMD
URQMD generator, Sqrt(S)=9: all nucleons in 1000 events
Total kinetic energy of all nucleons for each URQMD event
Total kinetic energy of all nucleonsdirected to ZDC
Optimistic results with UrQMD
LAQGSM generator, Sqrt(S)=5: all nucleons in 1000 events
Total kinetic energy of all nucleons and fragments for each LAQGSM event
Total kinetic energy of all nucleonsand fragments directed to ZDC
Taking into account spectator fragments
LAQGSM generator, Sqrt(S)=9: all nucleons in 1000 events
Total kinetic energy of all nucleons and fragments for each LAQGSM event
Total kinetic energy of all nucleonsand fragments directed to ZDC
Taking into account spectator fragments
All nucleons directed to the hole of ZDC (rectangle 10x10cm2)
0 % - 60 % 60 % - 80 % 80 % - 100 %
The centrality determination: The centrality determination: ZDC (energy) + number of charged barrel tracksZDC (energy) + number of charged barrel tracks
Interface between mpdroot and LAQGSM Interface between mpdroot and LAQGSM datadata
Class constructor:
MpdLAQGSMGenerator (const char* fileName, const Bool_t use_collider_system=kTRUE);
---------------------------------
Class usage in simulation macro:
fRun->SetName("TGeant4");
MpdLAQGSMGenerator* guGen= new MpdLAQGSMGenerator(filename);
primGen->AddGenerator(guGen);
ConclusionsConclusions• The LAQGSM data can be used for NICA/MPD simulations under mpdroot
package based on fairroot software.
• The LAQGSM angular distributions of the spectators differ from URQMD picture.
• “The proposed ZDC can measure the centrality alone (without data from another detectors) for the cases when it is known that the impact parameter is smaller than 8 -9 fm.
• One of the possible solutions is to use the particles multiplicity measured by TPC detector together with the value of energy deposition in ZDC. The selection of the most central and the most peripheral events in this case can be made by the corresponding large and small signal from the TPC.
• Another solution for the selection of the peripheral events with a small signal in ZDC an additional Zero Degree Neutron (ZDN) calorimeter can be installed after the 1rst dipole magnet of NICA.
• The selection of the most central and the most peripheral events can also be made by a small electromagnetic calorimeter placed out of the beam in front of ZDC,.
• The experimental study of the spectator distributions have to be performed on the extracted beam of NUCLOTRON-M at the fixed target. For such study the beam energy equals to (or less than) one NICA ring energy (sqrt(S)=2) is enough.”
Backup slidesBackup slides
Примеры определения центральности в различных экспериментах
y=0 y=3y>6
STARPHENIXNA49
NA49 ZDC Only
STAR TPC only
PHENIX BBC & ZDC
Study of spectator-nucleons and spectator-fragments Study of spectator-nucleons and spectator-fragments acceptance acceptance
for new ZDC geometryfor new ZDC geometry
Generators: URQMD 1.3 and LAQGSMCollision: mbias (bdb distribution), sqrt(S)=5 (GeV/u), 1000 eventsTransport: Geant3 and Geant4Software framework: mpdrootZDC special geometry: 2 thin layers (0.5mm silicon each) – old and new cross-section
ZDC positions: 287 cm from the collision pointMagnet: the latest geometry for MPD magnetMagnetic field: 0.5 TeslaNo pipeCave material: air
URQMD nucleons (directed and transported to ZDC entrance)
directed to
came to old ZDC came to new ZDCcame to hole
Geant3
Geant4
286182
284772
288372 15639
15520 216888
218084
LAQGSM nucleons (directed and transported to ZDC entrance)
directed to
came to old ZDC came to new ZDCcame to hole
Geant4
79290
?
56673 4944
? ?
38840
LAQGSM fragments (directed and transported to ZDC entrance)
directed to
came to old ZDC came to new ZDCcame to hole
Geant4
23110
?
19680 1425
? ?
14466
GeneratorAll directions: Number of nucleons
Rectangle 90x90 without
hole: Number of nucleons
Rectangle 90x90 with
hole Number of nucleons
Rectangle 10x10
(“hole”): Number of nucleons
URQMD386751 (100%) 301735 (78%) 286182 (74%) 15553 (4%)
LAQGSM387390 (100%) 266997 (69%) 138874 (36%) 128123 (33%)
GeneratorNew ZDC + hole: Number of nucleons
Hole: Number of nucleons
New ZDC: Number of nucleons
LAQGSM (p+n+A*fragments)
226640 (100%) 127964 (56.4%) 98676 (43.5%)
ZDC geometry A:ZDC geometry A:(Lead-Scint sandwich: “Lead (Lead-Scint sandwich: “Lead
16mm”)16mm”)
Geometry: cave, magnet, and ZDC (A and B). Cave material: air and vacuum.Magnetic Field: 0 (no field) and 0.5TGenerator: LAQGSM sqrt(S) = 5Transport: Geant4 and Geant3Events: 188
ZDC geometry B:ZDC geometry B:(Scint layer : “Lead 0”)(Scint layer : “Lead 0”)
LAQGSM AuAu, sqrt(S)=9,LAQGSM AuAu, sqrt(S)=9, Pt/A and theta vs Pt/A and theta vs bb
LAQGSM Sqrt(S)=9 GeV/u,LAQGSM Sqrt(S)=9 GeV/u, rapidity rapidity
Statistical Multifragmentation Model (SMM)Statistical Multifragmentation Model (SMM)
MSDM generator in SHIELD codeMSDM generator in SHIELD code