Download - Speed up ALICE simulation with TFluka
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Speed up ALICE simulation with TFluka
Ernesto Lopez Torres
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Problem
• HIJING Central event takes
~ 60 h with TFluka
~ 4 h with Geant3
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Why TFluka takes so long time?
First ideas:
• Energy transport cuts on region basics is not allow for hadrons, so we have 1MeV cut for all volumes
• There is not cut on number of track steps (for GEANT we have set max. 30 000 steps)
• More detail physics?
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Where is Fluka spending time?Some primary particle create a lot secondaries (105 - 106)
1. Small bug on HMPID: by error someone comment the initialization of the array with the quantum efficiency properties. QEff = 1031 instead of = 1
T0HMPID
Fix on the CVS
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Where is Fluka spending time?
# Primaries with (transp. time > 30s):
657 (1.1%)
with a total time:
151067 s = 41.9632 h (63.8%)
Transp. time(seg.) Volume name
134101.00 (37.3h) ALIC
6970.29 ZNST
1600.35 ZNSL
1351.01 ZPST
1338.15 QB28
766.762 QF29
650.828 ZPSL
594.577 ZDC
401.73 QBPM
376.511 QS29
192.871 ZNG4
190.431 ZNG3
177.951 ZNG1
177.051 ZNG2
168.76 HUWA
TFluka HIJING Pb-Pb 5.5TeV central event56140 particles(Laptop Centrino 2GHz 1Gb RAM)
Total transport time: 236389s (65.6 h)
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Where is Fluka spending time?• Small hadronic cut
(1MeV) on ZDC calorimeter (PIPE, etc) allow the develop of detail hadronic showers.
• Those hadrons escape the volume and develop the EM part also in ALIC
from AliZDCv2::CreateMaterials()
// Thresholds for showering in the ZDCs i = 1; //tantalum gMC->Gstpar(idtmed[i], "CUTGAM", .001); gMC->Gstpar(idtmed[i], "CUTELE", .001); gMC->Gstpar(idtmed[i], "CUTNEU", .01); gMC->Gstpar(idtmed[i], "CUTHAD", .01); …… i = 5; //lead gMC->Gstpar(idtmed[i], "CUTGAM", .001); gMC->Gstpar(idtmed[i], "CUTELE", .001); gMC->Gstpar(idtmed[i], "CUTNEU", .01); gMC->Gstpar(idtmed[i], "CUTHAD", .01); …. // Avoid too detailed showering along the beam line i = 7; //iron with energy loss (ZIRON) gMC->Gstpar(idtmed[i], "CUTGAM", .1); gMC->Gstpar(idtmed[i], "CUTELE", .1); gMC->Gstpar(idtmed[i], "CUTNEU", 1.); gMC->Gstpar(idtmed[i], "CUTHAD", 1.);
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Where is Fluka spending time?ZDC (ZEM) , PIPE, Compensator DIPO =>ALIC
AliMC::Stepping()
timer.Stop()
TH3F->Fill(x,y,z,timer.CpuTime());
...
timer.Start()
}
T0
ZEM
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Where is Fluka spending time?(ZDC (ZEM) , PIPE, Compensator DIPO) ->ALIC
1100 cm
ALIC
pi- P=92Gev #secondaries=17626 transport time=134s (2.3 min)
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Where is Fluka spending time?ZDC and PIPE => ALIC
TH3F->Fill(x,y,z,timer.CpuTime());
ZDC ZNSTZNSL
ZPST
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Where is Fluka spending time?
ZDC and PIPE -> ALIC
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To reduce the transport time in ALIC we introduced new volumes with high Energy cuts for gammas an electrons (0.1GeV)
ALIC
ALIZ
Shielding around dipole compensator
DCAR
PIAR
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We change from to
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Final Results
CVS With new volumes
TFluka 65 h 9 h
Geant3 4 h 2 h
# Primaries with (transp. time > 30s): 33 (0.05%)with a total time: 8497 s = 2.3 h (25.5%)
Transp. time(seg.)
Volume name
3841.32 ZNST
1209.11 ZPST
924.061 ZNSL
818.353 ALIZ
645.909 ZPSL
297.304 ZDC
104.881 ZNG4
103.681 ZNG3
100.791 ZNG2
100.521 ZNG1
53.16 ZNF3
51.78 ZNF4
50.12 ZNF2
49.53 ZNF1
3841.32 ZNST
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TODO
• Check how the changes could affect the ZDC performance.
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END
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Where is Fluka spending time?
ALIC
ZDC
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Final
FLUKA
GEANT