Luciano Pandola, INFN Gran Sasso

Luciano PandolaINFN Gran Sasso

Genova, July 18th, 2005

Geant4 and the underground physics

community

Luciano Pandola, INFN Gran Sasso

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

The goal of the G4 Collaboration –> to improve this situation, consistently with the available manpower.

• 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

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!

Luciano Pandola, INFN Gran Sasso

What is needed ? (my collection...)What is needed ? (my 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

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 A few examples of applications...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 (!)

Luciano Pandola, INFN Gran Sasso

A few examples of applications...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)

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...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...Dark matter experiment (WARP):

Goals: understand the background spectrum and its components

F. Di Pompeo, N. Ferrari, L. P.

energy (MeV) energy (MeV)

39Ar

85Kr

Data

Simulation(all components

included)

Data

Simulation(all components

included)

208Tl

Luciano Pandola, INFN Gran Sasso

Priorities for validationPriorities for validationSuggestions from ILIAS meeting in Prague

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

ConclusionsConclusions

Present ILIAS activity of cross-check and comparison between different Monte Carlo codes is very welcome

A lot of work!

Requires constant feedback and support from the experimental groups

Validation & cross-check should be done in synergy

Luciano Pandola, INFN Gran Sasso

Backup slides

Luciano Pandola, INFN Gran Sasso

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