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G4 simulation: No MCPoint where one should be... [message #14601]

Thu, 11 April 2013 11:07

Simone Esch
Messages: 37
Registered: August 2010
Location: Forschungszentrum Jülich...

continuous participant

From: *ikp.kfa-juelich.de

Dear PandaRoot Users,

in my simulation I found a problem with the creation of MCPoints.
I am simulating the decay ppbar ->Lambda Lambdabar -> pion_minus pion_plus proton antiproton.
Looking into the MC data I found a few cases, where a particle path crosses a sensitve material, but no MC Point was created (see pictures below).

We saw this in ~6 events.
I appeared something like in one event among 20 events and just for pions (plus and minus). The output from the simulation is (Verbose=2):

>>> Event 7
-I- PndSdsDetector: Adding Point at (-1.26017, -9.74078, 39.485) cm, (-1.26333, -9.74761, 39.515) cm,  detector /cave_1/CombinedLambdaDisks_0/LambdaDisk_1/LargeRing_0/StripSensorActiveLargeTrap_6 0, track 2, energy loss 561.051 keV
-I- PndSdsDetector: Adding Point at (-1.31324, -9.85647, 39.985) cm, (-1.31648, -9.86339, 40.015) cm,  detector /cave_1/CombinedLambdaDisks_0/LambdaDisk_1/LargeRing_1/StripSensorActiveLargeTrap_5 0, track 2, energy loss 459.511 keV
-I- PndSdsDetector: Adding Point at (5.38529, -0.204025, 38.985) cm, (5.38924, -0.205889, 39.015) cm,  detector /cave_1/CombinedLambdaDisks_0/LambdaDisk_1/SmallRing_0/StripSensorActiveSmallTrap_21 0, track 1, energy loss 113.605 keV
-I- PndSdsDetector: Adding Point at (7.74768, -1.98032, 59.985) cm, (7.75052, -1.98347, 60.015) cm,  detector /cave_1/CombinedLambdaDisks_0/LambdaDisk_2/LargeRing_1/StripSensorActiveLargeTrap_8 0, track 1, energy loss 225.731 keV

-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1002
      issued by : G4PropagatorInField::ComputeStep()
Particle is stuck; it will be killed.
  Zero progress for 51 attempted steps.
  Proposed Step is 1.56268e-05 but Step Taken is 1.56268e-05
  For Particle with Charge = 1 Momentum = 253.548 Mass = 139.57
 in volume DipolePip
*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------

-I- PndSdsDetector: Adding Point at (3.06891, 9.56976, 59.985) cm, (3.06929, 9.57481, 60.015) cm,  detector /cave_1/CombinedLambdaDisks_0/LambdaDisk_2/LargeRing_1/StripSensorActiveLargeTrap_11 0, track 0, energy loss 192.765 keV
 DIGI EXECUTION *********************
-I- PndSdsDetector: 0 points registered in this event.
[INFO   ] FairPrimaryGenerator: (Event 9) 4  primary tracks from vertex (0.000000, 0.000000, 0.000000 )  Event Time = 0.000000 (ns)

So nothing is reported about this point.

My system is:
openSUSE 12.2 Mantis - Kernel
external packages sep12
pandaroot rev 18841

Thanks

Simone

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Re: G4 simulation: No MCPoint where one should be... [message #14604 is a reply to message #14601]

Thu, 11 April 2013 16:07

StefanoSpataro
Messages: 2736
Registered: June 2005
Location: Torino

first-grade participant

From: *vpn.unito.it

Can you try with verbose level 3?
From the ProcessHits I can see that particles are stored in points only if the energy lows is different from 0, and maybe this is the case.

Still I do not understand the geant4 warning, since "DipolePip" I suppose is far from MVD. Can you check where this volume is exactly? I think the two things are different, the stopped particle and the missed point.

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Re: G4 simulation: No MCPoint where one should be... [message #14631 is a reply to message #14604]

Thu, 18 April 2013 11:12

Simone Esch
Messages: 37
Registered: August 2010
Location: Forschungszentrum Jülich...

continuous participant

From: *ikp.kfa-juelich.de

Hello stefano,

Tobias thought about this also, and inserted an output to check this.
Unfortionally something with the seed-setting is wrong, so we could not simulate the exactly the same events. But we saw the not existing MCPoint on other events where we are sure that energy was deposit.

But I can post another event with a higher verbose level.

Concerning the geant4 warning, the track goes further downstream and stops then at some point far away from the MVD, this are really two different things.

Greetings

Simone

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