results from simulations of the production of secondary particles at the pipe walls

The 3rd Work Meeting of the CBM-MPD STS Consortium, 1–4 June 2009, Sortavala, Karelia,

Russia

Results from simulations of the production of secondary particles at

the pipe walls

M.Baznat1, K.K.Gudima1, E.I.Litvinenko2 , Yu.Murin2

1Institute of Applied Physics, Academy of Science of Moldova, Moldova2JINR Dubna, Russia


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Outline

• Motivation of this study for CBM• LAQGSM generator• Rapidity• Transport of the spectators – nuclear fragments• Testing configurations of the beam pipe at the

STS region• Secondary particles and the pipe walls• Conclusion


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LAQGSM 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.


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LAQGSM 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]


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LAQGSM Au-Au sqrt(S)=5AGeV rapidity (5000 events)


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Interface to LAQGSM data

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);


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Geometry: Muon Magnet + 30 silicon planes:

0.3mm

0.004mm

Event generator: LAQGSMInput: a) “beam”, b) Au-Au, c) Au-p; Sqrt(S)=5 AGeVTransport: Geant4

The special testing configuration A:


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A:Transport of “the beam” with this configuration


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A: LAQGSM Au-Au sqrt(S)=5 AGeV 5000 events transported fragments


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A: LAQGSM p-Au sqrt(S)=5 AGeV 5000 events transported fragments


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A: Primary protons and fragments at z=50 and z=100 cm

Protons, z=50cm Protons, z=100cm Fragments, z=100cm

AuAu:

pAu:


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Geometry: Muon Magnet + 8 silicon planes:

0.08mm

Event generator: LAQGSMPipe: conical tube from Be or Al (with wall 2mm, and in B case 1mm Be)STS: 8 plane silicon stations 0.08mm, 10cm around the pipe, standard positionsCollision: Au-Au Sqrt(S)=5 GeV/uTransport: Geant4

The special testing configurations B and C:

B: Be–1mm 1.6º, Al -2mm 2.9º inside pipe: vacuum

C: Be–2mm 2.5º, Al -2mm 2.5º, inside pipe: vacuum, or helium


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B: Vertexes (r,z) of secondary particles, which came to STS planes(2200 LAQGSM events)

100% 114% [100%]

Be 1mm: Al 2mm:


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B: Vertexes (r,z) of secondary electrons, which came to STS planes

(2200 LAQGSM events)

76% (100%) 80% [70%] (104%)

Be 1mm: Al 2mm:


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B: Vertexes (r,z) of the secondary particles, which came to STS planes, that belong to the pipe wall

53% {100%} 70% [61%] {131%}

Be 1mm: Al 2mm:


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C: Secondary particles born in the pipe wall (1000events)

2mm Be+vacuum:

2mm Al+vacuum:

2mm Be+helium:

2mm Al+helium:

100%

111%

100.5%

114%

B: Be 1mm - 78% ; Al 2mm – 102%


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Maximal hit densities (per cm2 per event)

Allb allt allp z30 2.7 2.7 2.7 2.7

Allb allt allp z35 2.3 2.3 2.3 2.3

Allb allt allp z40 1.8 1.8 1.8 1.8

Allb allt allp z50 1.2 1.2 1.3 1.3

Allb allt allp z60 0.8 0.8 0.9 0.9

Allb allt allp z75 0.7 0.5 0.5 0.5

Allb allt allp z95 0.5 0.3 0.35 0.35

Allb allt allp z100 0.3 0.3 0.3 0.33

b<10 allt allp z30 2.4 2.4 2.4 2.4

b<10 allt allp z35 2.1 2.1 2.1 2.1

b<10 allt allp z40 1.6 1.6 1.6 1.6

b<10 allt allp z50 1.1 1.1 1.2 1.16

b<10 allt allp z60 0.7 0.8 0.8 0.8

b<10 allt allp z70 0.5 0.4 0.5 0.5

b<10 allt allp z95 0.3 0.3 0.3 0.3

b<10 allt allp z100

0.3 0.3 0.3 0.28

b<10 prim allp z30

2.2 2.2 2.2 2.2

b<10 prim allp z35

1.9 1.9 1.9 1.9

b<10 prim allp z40

1.4 1.4 1.4 1.4

b<10 prim allp z50

0.9 0.9 0.9 0.98

b<10 prim allp z60

0.6 0.6 0.6 0.6

b<10 prim allp z70

0.4 0.4 0.4 0.4

b<10 prim allp z95

0.27 0.27 0.26 0.27

b<10 prim allp z100

0.25 0.26 0.26 0.25

Be+vac Be+helAl+vac Al+hel

all

b<10

b<10prim

2.7 2.7

2.1 2.3

1.7 1.9

1.6 1.4

0.8 1.2

0.5 0.7

0.35 0.57

0.32 0.6

2.4 2.4

1.9 2.1

1.6 1.7

1.0 1.3

0.7 1.0

0.5 0.6

0.3 0.5

0.29 0.52

2.2 2.2

1.7 1.9

1.4 1.6

0.9 1.1

0.6 0.9

0.4 0.5

0.27 0.44

0.25 0.45

Al 2mm Be 1mmC: B:


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C: Secondary particles – hit density per cm2 per event

Be+vac

Al+vac

z=30cm

z=30cm

z=50cm

z=50cm

Max=0.23

Max=0.18

z=100cm

Max=0.26

Max=0.2

Max=0.07

Max=0.07

Max=0.21


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C: Secondary electrons – hit density per cm2 per event

Be+vac

Al+vac

z=30cm

z=30cm

z=50cm

z=50cm

Max=0.25 Max=0.18

Max=0.14Max=0.21


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C: Secondary electrons for different b rangesBe+vac

Al+vac

z=30cmz=50cm z=100cm


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B: Secondary electrons for different b ranges

Be+vac

Al+vac z=30cm z=50cm z=100cm


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Conclusion

• The pipe walls made from aluminium and berillium are very similar in respect to the secondary particle production (only 10% difference, but Al is much cheaper).

• The pipe cone angle less than 2.5° has the following disadvantages: -- big part of the spectator particles, which should be measured to define the centrality of the event, can not be registered by PSD; -- these spectator particles create a lot of secondary particles when pass through the pipe walls and when pass through the STS parts made from silicon.


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BACKUP SLIDES


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LAQGSM intranuclear cascade model


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The latest improvements of LAQGSM code


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B: Vertexes (r,z) of secondary particles, which came to STS planes


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B: All particles – hit distributions (arb.scale)

Be 1mm:

Al 2mm:

z=30cm

z=30cm

z=50cm

z=50cm


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Magnetic field behaviour near x=0 z=100cm


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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

results from simulations of the production of secondary particles at the pipe walls

Documents

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laqgsm auau sqrts

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lanl report laur

z of secondary electrons