1. Luciano Pandola, INFN Gran Sasso Luciano Pandola INFN Gran Sasso Genova, July 18 th, 2005 Geant4 and the underground physics community

2. Luciano Pandola, INFN Gran Sasso User 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!

3. Luciano Pandola, INFN Gran Sasso 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? 

4. Luciano Pandola, INFN Gran Sasso A few examples of applications... Double beta decay 76 Ge 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

5. Luciano Pandola, INFN Gran Sasso A few examples of applications... Preliminary results: 76 Ge 0 2  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 issue reliability unknown  we plan to cross-check (!)

6. Luciano Pandola, INFN Gran Sasso 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 60 Co source (in presence of the sample) detector sample source it works very well in this regime simulation data simulation data

7. Luciano Pandola, INFN Gran Sasso A few examples of applications... Dark matter experiment (ZEPLIN 3): Code from A. Howard and H. Araujo. Released as an advanced example of Geant4

8. Luciano Pandola, INFN Gran Sasso 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) 39 Ar 85 Kr Data Simulation (all components included) Data Simulation (all components included) 208 Tl

9. Luciano Pandola, INFN Gran Sasso Priorities for validation Suggestions 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.

10. 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

11. Luciano Pandola, INFN Gran Sasso Backup slides

12. Luciano Pandola, INFN Gran Sasso A few examples of applications... Experiment backgrounds internal detector radioactivity rock radioactivity  -induced neutron production shielding and veto systems Calibration Neutrons Gammas Optics Photon generation Light collection studies Detector response Scintillation Ionisation (thermal) Simulated Data Visualisation Run-time analysis Input to data analysis software G4 is uniquely suited for integrated simulations of Dark Matter detectors