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Файл:Моделирование (1 сем, мага) / geant4 / Geant4_4
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Chiral Invariant Phase Space (CHIPS)
• Quasmon: an ensemble of massless partons uniformly
distributed in invariant phase space
a 3D bubble of quark-parton plasma
can be any excited hadron system or ground state
hadron
• u,d,s quarks treated symmetrically (all massless)
• Critical temperature TC : model parameter which relates the
quasmon mass to the number n of its partons:
M
T
2
= 4n(n-1)T
Q
= 180 – 200 MeV
C
2
=> MQ ~ 2nT
C
C
• Quark fusion hadronization: two quark-partons may
combine to form an on-mass-shell hadron
• Quark exchange hadronization: quarks from quasmon and
neighbouring nucleon may trade places
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Skipping
• Electro-nuclear interacions
• Ion induced interactions
Already mentioned Binary light ion cascade
QMD model under development
Wilson Abrasion/Ablation models available
EM Dissociation model
• Isotope production model
• Radioactive decay
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Summary hadronics
• Geant4 hadronic physics allows user to choose how a
physics process should be implemented:
cross sections
models
• Many processes, models and cross sections to choose
from
hadronic framework makes it easier for users to add his
own cross section or model
• Recent improvements new additions in
FTF model
Precompound and de-excitation models
New Liege cascade implementation, including ABLA
Elastic scattering
Cross sections
46
Physics Lists
• Hadronic Physics lists provided by Geant4
help users in difficult task to
compose a complete and consistent set of
cross sections, processes, and models for all
particles
Rely on experience of hadronic developers
• Advanced examples provide lists for
specific cases
• Reference physics lists attempt to cover
many use cases
47
Reference Physics Lists (1)
• Reference physics lists attempt to cover a wide range of
use cases
Extensive validation by LHC experiments for simulation
hadronic showers
QGSP_BERT, or QGSP_BERT_EMV current favorite
New FTF_BIC is promising alternative
Comparison to TARC experiment testing neutron production
and transport demonstrates good agreement
QGSP_BIC_HP, QGSP_BERT_HP
user feedback, e.g. vi hypernews, is welcome
• Users responsible for validating results
• Documentation available from user support page
• Physics Lists User forum for questions and feedback
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Reference physics lists (2)
• Reference Physics Lists use modular
design
Reuse builders for several physics lists
Evolve lists following developments in G4
New options first offered in experimental lists
Adopting mature options in production lists
• Sharing of physics lists between users
LHC experiments required common physics
settings supported by G4
Sharing of experience, validation, etc…
49
Using Reference physics
In main(), pass a physics list to runManager:
G4VUserPhysicsList* physics = new FTF_BIC;
runManager->SetUserInitialization(physics);
50
Summary – Physics Lists
• Physics list provided and supported by
Geant4
Help users
Share experience
Follow developments in Geant4
Reduce risk of missing physics,
or using wrong models for specific type of application
51
Summary
• Hadronic physics offers models use
Parameterized modeling
Detailed theory inspired models
Precise data driven models
• Offer choice of physics detail,
at expense of CPU performance
• Continuing improvement in modeling
• Physics lists help users chosing hadronic physics
• Did not show
Extensive validation effort going on in hadronics
See still incomplete list in:
http://geant4.fnal.gov/hadronic_validation/validation_plots.htm
52
Backup slides
53
Соседние файлы в папке geant4