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None Tachyonic Particle Problem- Geant4 V 9.3- Ultra High Energy QGSP 

Forum: Hadronic Processes
Date: 07 Mar, 2011
From: Tomasz Sakrejda <Tomasz Sakrejda>

Hello,

I'm running Geant4 V9.3 on linux, and I've been trying to look at what geant4 gives out in the ultra-high-energy region because I want to compare some simulations with cosmic ray data. I know that the physics will very likely be innaccurate in the energy regime I'm looking at- but that's fine.

I've run into a problem when extending the energy past 500 PeV. The attached macro file will cause the error I'm interested in to occur in example Hadr01. Furthermore, if one randomizes the seeds using the setseeds command in /random/, it can change whether this error will occur- it seems that in some cases the proton undergoes a sucessful hard interaction before it can take a tachyonic step.

I know that I'm going far past Geant4's design specs here, but any help would be greatly appreciated.



This is the tail of the output:

### Run 0 start
Start Run processing.
EventAction: Event # 0 started

*********************************************************************************************************
* G4Track Information: Particle = proton, Track ID = 1, Parent ID = 0
*********************************************************************************************************

Step# X(mm) Y(mm) Z(mm) KinE(MeV) dE(MeV) StepLeng TrackLeng NextVolume ProcName
    0 0 0 -8e+07 5.16e+11 0 0 0 World initStep
    1 0 0 -4e+07 5.16e+11 1.96e-18 4e+07 4e+07 World Transportation
    2 0 0 -4e+07 5.16e+11 4.9e-26 1 4e+07 Target Transportation
    3 5.25e-05 2.71e-05 -4e+07 5.16e+11 0.216 1.02e+03 4e+07 Target hIoni
    4 0.154 0.29 -3.97e+07 5.16e+11 81.7 3.19e+05 4.03e+07 Target hIoni
    5 0.157 0.291 -3.97e+07 5.16e+11 3.17 1.32e+04 4.03e+07 Target hIoni
    6 0.156 0.29 -3.97e+07 5.16e+11 2.17 8.52e+03 4.03e+07 Target hIoni
    7 0.18 0.296 -3.96e+07 5.16e+11 14.3 5.76e+04 4.04e+07 Target hIoni
    8 0.18 0.296 -3.96e+07 5.16e+11 0.192 852 4.04e+07 Target Transportation
    9 0.183 0.295 -3.96e+07 5.16e+11 3.55 1.52e+04 4.04e+07 Target hadElastic
   10 0.183 0.298 -3.96e+07 5.16e+11 3.92 1.44e+04 4.04e+07 Target hIoni
   11 0.175 0.312 -3.95e+07 5.16e+11 12.3 4.36e+04 4.05e+07 Target hIoni
   12 0.15 0.461 -3.93e+07 5.16e+11 47.8 1.9e+05 4.07e+07 Target hIoni
   13 0.162 0.484 -3.93e+07 5.16e+11 15.8 5.88e+04 4.07e+07 Target hIoni
   14 0.162 0.484 -3.92e+07 5.16e+11 22 7.78e+04 4.08e+07 Target Transportation
   15 0.16 0.486 -3.92e+07 5.16e+11 3.66 1.41e+04 4.08e+07 Target hIoni
   16 0.364 0.494 -3.9e+07 5.16e+11 60.4 2.32e+05 4.1e+07 Target hIoni
   17 0.364 0.496 -3.89e+07 5.16e+11 2.29 1.05e+04 4.11e+07 Target hadElastic
   18 0.35 0.558 -3.88e+07 5.16e+11 29.8 1.07e+05 4.12e+07 Target hIoni
   19 0.35 0.558 -3.88e+07 5.16e+11 8.1 3.58e+04 4.12e+07 Target Transportation
   20 0.352 0.56 -3.88e+07 5.16e+11 3.32 1.32e+04 4.12e+07 Target hIoni
   21 0.33 0.51 -3.87e+07 5.16e+11 27.9 9.59e+04 4.13e+07 Target hIoni
-49.10875115920524 579.5446488407947 493.677 134.9764
In include/G4GeneralPhaseSpaceDecay.hh, line 117:
===> G4GeneralPhaseSpaceDecay::Pmx energy in cms > mass1+mass2
ZMxpvTachyonic:
ZMxpvTachyonic: boostVector computed for a non-timelike LorentzVector
at line 185 in file LorentzVector.cc
ZMxpvTachyonic thrown:
ZMxpvTachyonic: Boost Vector supplied to set HepLorentzRotation represents speed >= c.
at line 33 in file LorentzRotation.cc
terminate called after throwing an instance of 'ZMxpvTachyonic'
  what(): ZMxpvTachyonic: Boost Vector supplied to set HepLorentzRotation represents speed >= c.



   Attachment:
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2011/03/07/23.16-44763-Hard01.txt

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1 None: Re: Tachyonic Particle Problem- Geant4 V 9.3- Ultra High Energy QGSP   (Tomasz Sakrejda - 08 Mar, 2011)
2 None: Re: Tachyonic Particle Problem- Geant4 V 9.3- Ultra High Energy QGSP   (Dennis H. Wright - 08 Mar, 2011)
1 Ok: Re: Tachyonic Particle Problem- Geant4 V 9.3- Ultra High Energy QGSP   (Tomasz Sakrejda - 08 Mar, 2011)
2 News: Re: Tachyonic Particle Problem- Geant4 V 9.3- Ultra High Energy QGSP   (Tomasz Sakrejda - 08 Mar, 2011)
1 Idea: Re: Tachyonic Particle Problem- Geant4 V 9.3- Ultra High Energy QGSP   (Vladimir Ivanchenko - 09 Mar, 2011)
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