Luciano Pandola, INFN Gran Sasso Luciano Pandola INFN Gran Sasso Zaragoza, September 15 th, 2005 Geant4 and the underground physics community... (part II)

Luciano Pandola, INFN Gran Sasso Validation of physics processes Processes for photons (Standard, Low Energy, Penelope) extensively validated in the last months The situation for EM physics is encouraging... Similar work has been done for electrons and ions, or is currently in progress Intensity/Z (eV/sr keV) Photon energy (keV) Bremms. for 70 keV e -  = 45 o K. Amako et al., IEEE Trans. Nucl. Scie. 52 (2005) 910 Also comparisons with other codes (EGS) have been performed E. Poon and F. Verhaegen, Med. Phys. 32 (2005) 1696 K. Murakami et al., IEEE Nucl. Scie. Symp., Conf. Record 2004, IEEE 4 (2004) 2120

Luciano Pandola, INFN Gran Sasso Validation of physics processes What about hadronic physics? A similar systematic effort has not been performed yet but... Large-scale automatized regression testing of hadronic physics (mainly intended for calorimetry) using the GRID project (  2 CPU·year equivalent) 8 primary particles  5000 events  5 physics lists  24 energies Same tools usable for physics validation (rather than regression!) Start systematically ASAP using test beam data LHEP, QGSP, QGSC, QGSP_BIC, QGSP_BERT QGSP π GeV Geant4 7.1 Geant4 7.0

Luciano Pandola, INFN Gran Sasso data bertini binary From H. Günther, G. Folger and A. Heikkinen Isotope production Real ongoing validation effort.... no experimental data

Luciano Pandola, INFN Gran Sasso Isotope production Data are readily available only for high-Z targets (Au, Pb, U) For light targets, only specific products are usually accounted for (e.g. medical applications)  only single cross sections can be compared The failure for binary cascade to reproduce elements with Z < 50 from gold is not a feature of binary cascade and precompound models, but it is likely to be due to a bug in the fission-related code It is currently under investigation  results should change quite a bit in the near future

Luciano Pandola, INFN Gran Sasso Excitation functions Excitation functions for proton primaries Geant4 with Bertini cascade model (from P. Kaitaniemi and A. Heikkinen, Helsinki Institute of Physics.) 89 Y  74 As 89 Y  88 Zr 89 Y  85 Sr 127 I  121 I 127 I  126 I 127 I  122 Xe I asked the same plots for Ge isotopes...

Luciano Pandola, INFN Gran Sasso data bertini binary From H. Günther, G. Folger and A. Heikkinen Isotope production no experimental data

Luciano Pandola, INFN Gran Sasso General remarks: Isotope production Bertini cascade agrees with data better than binary cascade Binary cascade over-estimates the heavy secondaries and does not produce light secondaries (bug not related to the cascade itself)  improvements expected in a short time Models can reproduce correctly the slope Both models systematically favour elements with even Z From H. Günther, G. Folger and A. Heikkinen

Luciano Pandola, INFN Gran Sasso Isotope production Concerning underground physics: The cosmogenic production of 16 N in water calculated with Geant4 agrees with FLUKA (hep-ph/ v1) at better than 50%. Consistent with what found by Vitaly and Henrique concerning muon-induced neutrons (hep-ex/ )

Luciano Pandola, INFN Gran Sasso 1-keV spurious peak At Valencia meeting it was reported the existence of a spurious neutron peak of energy 1 keV produced by G4MuNuclearInteraction and neutron Inelastic Process Known feature. It depends on the parametrized models. HPW reply: “This is an intended model feature. It is useful that the line shows up. It is indicating that if this area of energies in relevant to a user, the model is not appropriate” (bug reports #561 and #724) QGSP_BIC and QGSP_BERT are free from this behaviour Alternatively, edit by hand the file hadronic/util/src/G4ReactionDynamics.cc

Luciano Pandola, INFN Gran Sasso One bug relevant for Ge 0 2 ... Geant4 bug report #526 For neutron inelastic scattering on Germanium Ge (n,n’) Ge * the produced nucleus in the final state is Ga instead of Ge (  wrong de-excitation gammas!) The bug is in: processes/hadronic/models/neutron_hp/G4NeutronHPNames.cc Official patch not yet available (I have my own...) I don’t know if it happens also with other elements

Luciano Pandola, INFN Gran Sasso Summary First iteration with the Geant4 Collaboration. Requirements coming from the underground physics community are well known (meeting in Genova, July). Good will to fulfill them, consistently with the available manpower The validation program is continuing, expecially in the EM physics side. Something is moving also in the hadronic physics sector, though the effort is LHC-driven Validation activity concerning the isotope production in Bertini and Binary cascade. The reliability and the limits of the two models are more clear Spurious 1-keV neutron peak declared to be an inteded feature. One bug found for neutron IS on Ge (  patch available)