Luciano Pandola

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• Luciano Pandola
• INFN Gran Sasso
• Genova, July 18th, 2005

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User requirements validation
(My feeling) Geant4 is still not considered a
fully established and trustworthy Monte Carlo in
the underground physics community

• small overlap between the Collaboration and the
  experiments ( 2)
• no test-beams available, so validation much more
  complicated
• requires extensions to High Energy (e.g. muons)
  and to LowEnergy (e.g. fluorescence) ? typically
  decoupled in the modular development of Geant4

The goal of the G4 Collaboration gt to improve
this situation, consistently with the available
manpower.
Effort for a more complete validation plan (what
are the priorities?). Needs strong connection
with experimental and MC groups of the
experiments, also for providing data!
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What is needed ? (my collection...)

• High energy muons interactions showers
• neutron and hadron production (critical for DM
  experiments)
• isotope production

has ever been validated or cross-checked?

• 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)

?
?
?
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A few examples of applications...
Double beta decay 76Ge experiment (GERDA
Majorana)
OO toolkit based on Geant4 (MaGe)
Flexible enough to allow
common parts (e.g. generators, physics, other
tools) ? not duplicated
experiment-specific parts (geometry, i/o)
Preliminary physics studies g background from
outside and from structures (ropes, contact) ?
efficiency of segmentation/anticoincidence backgro
und from cosmic ray muons
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A few examples of applications...
Preliminary results
Goal 10-3-10-4 counts/keVkgy _at_ Qbb
Achievable for g and cosmic ray m (with dedicated
veto)
Cosmic ray muons
mainly from EM showers ? physics reliable
76Ge 0n2b region
Fission, (a,n) and cosmogenic neutrons are not an
issue (very different for DM expts)
physics reliable? (with the proper physics list)
? work in progress from DM groups
Isotope production not an issue
reliability unknown ? we plan to cross-check (!)
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A few examples of applications...
Small (simple) 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)
it works very well in this regime
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A few examples of applications...
Dark matter experiment (ZEPLIN 3)
Code from A. Howard and H. Araujo. Released as
an advanced example of Geant4
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A few examples of applications...
F. Di Pompeo, N. Ferrari, L. P.
Dark matter experiment (WARP)
39Ar
85Kr
208Tl
energy (MeV)
energy (MeV)
Goals understand the background spectrum and its
components
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Priorities for validation
Suggestions from ILIAS meeting in Prague

• Production of m-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.
Validation is this field is a difficult task ?
close collaboration required with MC and
experimental groups
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Conclusions
A lot of work!
Requires constant feedback and support from the
experimental groups
Validation cross-check should be done in synergy
Present ILIAS activity of cross-check and
comparison between different Monte Carlo codes is
very welcome
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Backup slides
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A few examples of applications...
Experiment backgrounds internal detector
radioactivity rock radioactivity m-induced
neutron production shielding and veto systems
G4 is uniquely suited for integrated simulations
of Dark Matter detectors
Detector response Scintillation Ionisation (therma
l)
Optics Photon generation Light collection studies
Simulated Data Visualisation Run-time
analysis Input to data analysis software
Calibration Neutrons Gammas