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GEANT4 – Simulations of muon-induced neutrons for the

Experiment. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft. Institut für Kernphysik. GEANT4 – Simulations of muon-induced neutrons for the. EDELWEISS II muon veto, Geant4 physics, muon induced neutrons, muon-nuclear interaction, summary & discussion.

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GEANT4 – Simulations of muon-induced neutrons for the

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  1. Experiment Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft Institut für Kernphysik GEANT4 – Simulations of muon-induced neutronsfor the EDELWEISS II muon veto, Geant4 physics, muon induced neutrons, muon-nuclear interaction, summary & discussion ILIAS-N3, BSNS-working group meeting Valencia, 15.04.2005

  2. EDELWEISS II – muon veto system EDWI (1kg)  EDWII (40kg)  ’total exposure’ ×100  neutron background (Erecoil > 30 keV)main source: muon-induced neutrons from rock and shielding muon veto system 10/2005: 21×320g Ge/NTD thermistor 7 ×400g Ge/NbSi ‘thin film sensors’ sensitivity goal: ×100 Markus Horn: GEANT4 – Simulations of muon-induced neutrons

  3. Tasks: Implement energy and angular distribution of muon flux in underground lab (LSM, Fréjus mountain) Deep Inelastic Scattering (DIS) of high energy muons in rock and shielding material Test & understand Geant4 `muNucl` interaction (energy & angular distribution) Comparison of Geant4 with G3, FLUKA, MCNP, etc. (`benchmarks`) Neutron tracking in the detector area and the surrounding EDELWEISS Geant4 – background simulations Markus Horn: GEANT4 – Simulations of muon-induced neutrons

  4. Geant4 7.0 physics list Inelastic models used: • Muon-photonuclear >1GeV • Photonuclear < 3GeV • QGSP (>12GeV): high energetic hadronic interaction incl. pre-equilibrium-cascade model, nuclear evaporation & multi-fragmentation • BiC (<6GeV): intra-nuclearbinary cascade model • Neutron-HP (<19MeV): data-driven model  details s.a.Geant4- Collab. Markus Horn: GEANT4 – Simulations of muon-induced neutrons

  5. Neutron yield • material: CnH2n • neutron yield in relative good agreement with experimental data • differences toKudryavtsev et al. (hep-ex/0411026) • Why 15% lower yield ?  Physics List, G4version ? • Correction of yield at 10GeV • MC error bars ? Statistics and systematics ? Rare events with high n-multiplicity ~2×105 µ(10-1000GeV), CnH2n, 3200g/cm2 Markus Horn: GEANT4 – Simulations of muon-induced neutrons

  6. Neutron multiplicity • µ-ind. spallation (in most cases only once per event) produces few hadrons • secondary neutrons by hadronic showers on average 4-5 neutrons per event • maximum multiplicity ~100 -1000(depending on material and energy, e.g. Pb, Eµ=1TeV) ~2×105 µ(280GeV), CnH2n, 3200g/cm2 Markus Horn: GEANT4 – Simulations of muon-induced neutrons

  7. material: CnH2n deep inelastic muon-nucleus interaction via virtual photon photonuclearreactions in el.-m. showers triggered by incident muon secondary neutron production (π-N, π-absorption, p-N, etc.) Muon induced neutrons >105 µ(10-1000GeV), CnH2n, 3200g/cm2 Markus Horn: GEANT4 – Simulations of muon-induced neutrons

  8. Diff. energy spectrum of neutrons • material: CnH2n • muon energy: 280 GeV • LVD exp. data(measurement in GranSasso-underground lab) scaled (x6)  neutron detector efficiency • good agreement with FLUKA simulations(Kudryavtsev et al. hep-ex/0411026) ~105 µ(280GeV), CnH2n, 3200g/cm2 Markus Horn: GEANT4 – Simulations of muon-induced neutrons

  9. Neutron yield in different materials • materials: • CnH2n, • Fréjus & LNGS rock, • concrete, • copper, • lead • muon energy: 280 GeV • max. differenceFLUKA ↔ Geant4 less than factor ×2 ~105 µ(280GeV), 3200g/cm2 Markus Horn: GEANT4 – Simulations of muon-induced neutrons

  10. Muon-nucleus interaction I preliminary • energy transfer of muon-nucleus interaction (`muNucl´) 200MeV E 280GeV E´ Etrans ~2×105 µ(280GeV), CnH2n, 3200g/cm2 Markus Horn: GEANT4 – Simulations of muon-induced neutrons

  11. Muon-nucleus interaction II - muons preliminary • angular distribution of muon-nucleus interaction (`muNucl´) µ µ´ θ ~2×105 µ(280GeV), CnH2n, 3200g/cm2 Markus Horn: GEANT4 – Simulations of muon-induced neutrons

  12. Muon-nucleus interaction III - neutrons preliminary • kinetic energy distribution of `muNucl´-neutrons sec. particles µ µ´ n ~2×105 µ(280GeV), CnH2n, 3200g/cm2 Eneutron Markus Horn: GEANT4 – Simulations of muon-induced neutrons

  13. Muon-nucleus interaction IV - neutrons preliminary • angular distribution of muon-nucleus interaction (`muNucl´) sec. particles µ µ´ n θ ~2×105 µ(280GeV), CnH2n, 3200g/cm2 Eneutron Markus Horn: GEANT4 – Simulations of muon-induced neutrons

  14. Muon-nucleus interaction V - neutrons preliminary Markus Horn: GEANT4 – Simulations of muon-induced neutrons

  15. differences to Kudryavtsev et al. (hep-ex/0411026): Due to slightly different physics list ? Or G4 version ? How to correct neutron yield for 10GeV muons ? (benchmarks) neutron multiplicity and statistics Muon-nucleus interaction: Why minimum energy transfer of 200MeV ? Why 1keV – line in neutron spectrum ? Why backward peak in angular distribution ? (Problems with G4 core dump - G4Fragment: pi±) Open questions benchmarks (ü) µ - DIS Markus Horn: GEANT4 – Simulations of muon-induced neutrons

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