Luciano Pandola, INFN Gran Sasso Luciano Pandola INFN Gran Sasso Valencia, April 14 th, 2005 Geant4...
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Transcript of Luciano Pandola, INFN Gran Sasso Luciano Pandola INFN Gran Sasso Valencia, April 14 th, 2005 Geant4...
Luciano Pandola, INFN Gran Sasso
Luciano Pandola
INFN Gran Sasso
Valencia, April 14th, 2005
Geant4 and the underground physics
community
Luciano Pandola, INFN Gran Sasso
What is ?What is ?
OO Toolkit for the simulation of the interaction of particles with OO Toolkit for the simulation of the interaction of particles with mattermatter– physics processes (EM, hadronic, optical) cover a comprehensive
set of particles, materials and over a wide energy range– it offers a complete set of functionalities (tracking, geometry,
hits)– born for the HEP community, but extensively used also in
medical physics, astroparticle physics and space applications
It is also an experiment of distributed software production and managementdistributed software production and management, as a large international Collaborationlarge international Collaboration with the participation of various experiments, labs and institutes
Has been creating exploiting a rigorous software engineering rigorous software engineering and Object Object Oriented technologies, Oriented technologies, implemented in the flexible C++ language
Luciano Pandola, INFN Gran Sasso
Where does it come from?Where does it come from?Where does it come from?Where does it come from?
Very high statistics to be simulated – robustness and reliability for large scale production
Exchange of CAD detector descriptions– very complex geometries and experimental setups
Transparent physics for experimental validation – possibility to use alternative/personalized physics models
Physics extensions to high energies– LHC, cosmic ray experiments
Physics extensions to low energies– space science, astrophysics, medical physics, astroparticle physics
Luciano Pandola, INFN Gran Sasso
Uniform treatmentUniform treatment of electromagnetic and hadronic processes
Abstract interfaceAbstract interface to physics processes
– Tracking independent from physics
Distinction between processes and modelsprocesses and models– Often multiple models for the same physics process (complementary/alternative)
Users can choose those that best match their needs (energy range, precision vs. CPU time)
Open system– Users can easily create and use their own models
Transparency– Calculation of cross-sections independent from the way they are accessed (data files, analytical
formulae etc.)– Distinction between the calculation of cross sections and their use– Calculation of the final state independent from tracking
PhysicsPhysicsPhysicsPhysics
Luciano Pandola, INFN Gran Sasso
Physics class structurePhysics class structurePhysics class structurePhysics class structure
Only production cuts for e- and ’s are
used
all particles tracked until
they stop
Drawback: difficult to choose the most suitable process (some lack of documentation, exp. for hadronic models) black box approach
Advantages: very flexible, multiple alternative (user-defined) models
Luciano Pandola, INFN Gran Sasso
User requirements & validationUser requirements & validationUser requirements & validationUser requirements & validation
Geant4 is open to user requirements concerning new capabilities and physics models
http://pcitapiww.cern.ch/asd/cgi-bin/geant4/urd/Problems:
- manpower (usually short)
- specific expertise needed
- modular development (some groups are more active than others)...
Geant4 was born at CERN so it was mainly “tuned” and
developed by people working in the accelerator groups
well-established MC, validation from test-beams of the experiments
Events
/10
nA
Events
/10
nA
-100-100 10010000 200200 300300 400400 50050000
600600
100100200200
300300400400500500
700700800800
Calorimeter Signal [nA]Calorimeter Signal [nA]
180 GeV μ
Luciano Pandola, INFN Gran Sasso
User requirements & validationUser requirements & validationUser requirements & validationUser requirements & validation
Geant4 became a well-established “reference” Monte Carlo also in other sectors medical physics
15x15 cm2
15x15 cm2
Differences
e.m. Physics Geant4-05-00
Depth dose and profile curves for clinical x-ray beams
Bragg-peak of 60-MeV protons
for cancer therapy
Require accuracy of EM processes (LowE)
Luciano Pandola, INFN Gran Sasso
Physics Validation Physics Validation
SystematicSystematic and extensive validationextensive validation of the whole physics content is fundamental in Geant4
Specific validations at different levels
MicroscopicMicroscopic physics validation of each modelof each model cross section, angular/energy distributions
MacroscopicMacroscopic validation with experimental use cases full simulation of experimental set-ups
necessary stage to guarantee reliable simulations
The results of simulations must be quantitatively compared with established and authoritative
reference data experimental measurements on refereed journals and/or open standard dabatases (ICRU, NIST, Livermore)
Luciano Pandola, INFN Gran Sasso
User requirements & validationUser requirements & validationUser requirements & validationUser requirements & validation
Geant4 EM physics models (“standard” and “low energy”) are being validated in a systematic and quantitative way
Data: Shimizu et al, Appl.
Phys. 9 (1976) 101Al slab
E = 20 keV
1040 nm
320 nm
electron transmission
G4Standard
G4 LowE
NIST
G4 LowE
Data
electron backscatteringphoton attenuation
K. Amako et al., Validation of Geant4 electromagnetic physics versus the NIST databases, submitted to IEEE Trans. Nucl. Scie.
Luciano Pandola, INFN Gran Sasso
User requirements & validationUser requirements & validationUser requirements & validationUser requirements & validation
(My feeling) Geant4 is still not considered a fully established and trustworthy Monte Carlo in the underground physics community
The medium-term goal of the G4 Collaboration is to improve this situation, consistently with the available manpower.
• small overlap between the Collaboration and the experiments ( = 3)
• no test-beams available, so validation much more complicated
• requires extensions to High Energy (e.g. muons) and to Low Energy (e.g. fluorescence) typically “decoupled” in the modular development of Geant4
Effort for a more complete validation plan (what are the priorities?). Needs strong connection with experimental and MC groups of the experiments (= us), also for providing data!
Luciano Pandola, INFN Gran Sasso
What do we need ? (my What do we need ? (my collection...)collection...)What do we need ? (my What do we need ? (my collection...)collection...)
High energy muons interactions & showers:
• neutron and hadron production (critical for DM experiments)
• isotope production
Low energy electromagnetic extensions:
• precise tracking of low-energy leptons and hadrons
• more precise energy and angular spectra
• atomic de-excitation (e.g. fluorescence x-rays)
Other:
• very precise decay schemes for Radioactive decay (low-branching channels)
• EC decay (with fluorescence) Other decays (e.g. spont. fission)
has ever been validated or cross-checked?
Luciano Pandola, INFN Gran Sasso
Low energy EM extensionsLow energy EM extensionsLow energy EM extensionsLow energy EM extensions
Geant4 provides dedicateddedicated Low EnergyLow Energy EM models electrons, positrons and gammas down to 250 eV
Based on EPDL97, EEDL and EADL evaluated data libraries
shell effects
neutrino/dark matter experiments, space and medical applications
Possible thanks to the OO-OO-oriented technologyoriented technology used
in Geant4
The whole physics content of the Penelope Monte Carlo codePenelope Monte Carlo code has been
re-engineered into Geant4
New complete set of alternative and dedicated
low energy EM physics models (atomic effects
included)
processes for photons: release 5.2, for electrons: release 6.0
Att
enuati
on
coeff
. (c
m2/g
) NIST data
Penelope
Hadron, anti-proton and ion models
Luciano Pandola, INFN Gran Sasso
A few examples of applications...A few examples of applications...A few examples of applications...A few examples of applications...
Double beta decay 76Ge experiment (GERDA & Majorana):
common parts (e.g. generators, physics, other tools) not duplicated
OO toolkit based on Geant4 (MaGe)
Flexible enough to allow
experiment-specific parts (geometry, i/o)
Preliminary physics studies:
background from outside and from structures (ropes, contact) efficiency
of segmentation/anticoincidence
background from cosmic ray muons
Luciano Pandola, INFN Gran Sasso
A few examples of applications...A few examples of applications...A few examples of applications...A few examples of applications...
Preliminary results:
76Ge 02 region
Cosmic ray muons
Achievable for and cosmic ray (with dedicated veto):
Fission, (,n) and cosmogenic neutrons are not an issue
(very different for DM expts)
mainly from EM showers physics reliable
physics reliable? (with the proper physics list) work in progress
from DM groups
Goal 10-3-10-4 counts/keV·kg·y @ Q
Isotope production not an issuereliability unknown we plan
to cross-check with Fluka
Luciano Pandola, INFN Gran Sasso
A few examples of applications...A few examples of applications...A few examples of applications...A few examples of applications...
Small (stupid) application derived from studies of environmental radioactivity from rocks and sands
Geant4 (LowE EM) can reproduce very well the results of a calibration with a 60Co source (in presence of the sample)
detectorsample
source
it works very well in this regime
simulation
datasimulation
data
Luciano Pandola, INFN Gran Sasso
A few examples of applications...A few examples of applications...A few examples of applications...A few examples of applications...
Dark matter experiment (ZEPLIN 3):
Code from A. Howard and H. Araujo.
Released as an advanced example of Geant4
Luciano Pandola, INFN Gran Sasso
A few examples of applications...A few examples of applications...A few examples of applications...A few examples of applications...
Experiment backgroundsinternal detector radioactivityrock radioactivity-induced neutron productionshielding and veto systems
CalibrationNeutronsGammas
OpticsPhoton generationLight collection studies
Detector responseScintillationIonisation(thermal)
Simulated DataVisualisationRun-time analysisInput to data analysis software
G4 is uniquely suited for integrated simulations of Dark Matter detectors
Luciano Pandola, INFN Gran Sasso
A few examples of applications...A few examples of applications...A few examples of applications...A few examples of applications...
Electric fields1.1. Ionisation extractionIonisation extraction
2.2. Drift in liquid xenonDrift in liquid xenon
3.3. Extraction to gasExtraction to gas
4.4. Drift in gasDrift in gas
5.5. Luminescence lightLuminescence light
Light collection maps
Luciano Pandola, INFN Gran Sasso
Our priorities for validationOur priorities for validationOur priorities for validationOur priorities for validation
Suggestions from Prague meeting forwarded to the G4 Collaboration
Validation is this field is a difficult task close collaboration required with MC and experimental groups
• Production of -induced neutrons in high-Z materials
• Propagation of Low Energy neutrons (up to a few MeV)
• Inelastic scattering of neutrons
• Interactions of high-energy muons
• Isotope production
comparison with FLUKA, experimental data
comparison with MCNP, experimental data
comparison with other codes t.b.d.
Luciano Pandola, INFN Gran Sasso
ConclusionsConclusionsConclusionsConclusions
Present ILIAS activity of cross-check and comparison between different Monte Carlo codes is very welcome
Open a link between the Geant4 Collaboration and the experimental groups working in underground physics ( & ILIAS)
Geant4 Collaboration willing to address the requests (expecially for validation) coming from our community
A lot of work!
Requires constant feedback and support from the experimental groups
Validation & cross-check should be done in synergy