Geant4 Physics Validation and Geant4 Physics Validation and - PowerPoint PPT Presentation

Geant4 Physics Validation and Geant4 Physics Validation and Verification Verification Ions Ions Koi, Tatsumi SLAC/SCCS Koi, Tatsumi SLAC/SCCS

Neutron & Ion Models High Precision neutron down to thermal energy Inventory Elastic Inelastic Capture Fission Evaporation Pre- FTF String (up to 20 TeV) Fermi breakup compound Multifragment QG String (up to 100 TeV) Photon Evap Binary cascade Rad. Decay Neutrons Bertini cascade Fission LE pp, pn HEP ( up to 15 TeV) LEP Thermal 1 MeV 10 MeV 100 MeV 1 GeV 10 GeV 100 GeV 1 TeV (/n) Evaporation Pre- Fermi breakup Ions compound Multifragment Binary cascade Light Ions Photon Evap Rad. Decay Wilson Abrasion&Ablation Electromagnetic Disosiation

Ion Physics Ion Physics Inelastic Reactions Inelastic Reactions • Cross Sections • Cross Sections – Tripathi Tripathi, , Shen Shen, , Kox Kox and and Sihver Sihver Formula Formula – • Model • Model – G4BinaryLightIon G4BinaryLightIon – – G4WilsonAbrasion G4WilsonAbrasion –

Cross Sections Cross Sections • Many cross section formulae for NN collisions are • Many cross section formulae for NN collisions are included in Geant4 included in Geant4 – Tripathi Tripathi Formula NASA Technical Paper TP Formula NASA Technical Paper TP- -3621 (1997) 3621 (1997) – – Tripathi Tripathi Light System NASA Technical Paper TP Light System NASA Technical Paper TP- -209726 (1999) 209726 (1999) – – Kox Kox Formula Phys. Rev. C 35 1678 (1987) Formula Phys. Rev. C 35 1678 (1987) – – Shen Shen Formula Nuclear Physics. A 49 1130 (1989) Formula Nuclear Physics. A 49 1130 (1989) – – Sihver – Sihver Formula Phys. Rev. C 47 1225 (1993) Formula Phys. Rev. C 47 1225 (1993) • These are empirical and parameterized formulae with • These are empirical and parameterized formulae with theoretical insights. theoretical insights. • G4GeneralSpaceNNCrossSection was prepared to assist • G4GeneralSpaceNNCrossSection was prepared to assist users in selecting the appropriate cross section formula. users in selecting the appropriate cross section formula.

Inelastic Cross Section Inelastic Cross Section C12 on C12 C12 on C12

Binary Cascade Binary Cascade ~ Model Principals~ ~ Model Principals~ • In Binary Cascade, each participating nucleon is seen as • In Binary Cascade, each participating nucleon is seen as a Gaussian wave packet, (like QMD) a Gaussian wave packet, (like QMD) ⎛ ⎞ 3 ⎛ ⎞ 4 ( ) ⎟ ⎜ ⎟ ( ) ⎜ 2 ⎟ − 2 φ x , q , p , t = exp ⎜ + ip t x ( ) ⎝ ⎠ ( ( ) ) 2 i i L π i ⎝ ⎠ L x − q t i • Total wave function of the nucleus is assumed to be • Total wave function of the nucleus is assumed to be direct product of these. (no anti- -symmetrization symmetrization) ) direct product of these. (no anti • This wave form have same structure as the classical • This wave form have same structure as the classical Hamilton equations and can be solved numerically. Hamilton equations and can be solved numerically. • The Hamiltonian is calculated using simple time • The Hamiltonian is calculated using simple time independent optical potential. (unlike QMD) independent optical potential. (unlike QMD)

Binary Cascade Binary Cascade ~ nuclear model ~ ~ nuclear model ~ • 3 dimensional model of the nucleus is constructed • 3 dimensional model of the nucleus is constructed from A and Z. from A and Z. • Nucleon distribution follows • Nucleon distribution follows – A> 16 Woods A> 16 Woods- -Saxon model Saxon model – – Light nuclei harmonic Light nuclei harmonic- -oscillator shell model oscillator shell model – • Nucleon • Nucleon momenta momenta are sampled from 0 to Fermi are sampled from 0 to Fermi momentum and sum of these momenta momenta is set to 0. is set to 0. momentum and sum of these • time • time- -invariant scalar optical potential is used. invariant scalar optical potential is used.

Binary Cascade Binary Cascade ~ G4BinaryLightIonReaction ~ ~ G4BinaryLightIonReaction ~ • Two nuclei are prepared according to this model • Two nuclei are prepared according to this model (previous page). (previous page). • The lighter nucleus is selected to be projectile. • The lighter nucleus is selected to be projectile. • Nucleons in the projectile are entered with • Nucleons in the projectile are entered with position and momenta momenta into the initial collision into the initial collision position and state. state. • Until first collision of each nucleon, its Fermi • Until first collision of each nucleon, its Fermi motion is neglected in tracking. motion is neglected in tracking. • Fermi motion and the nuclear field are taken • Fermi motion and the nuclear field are taken into account in collision probabilities and final into account in collision probabilities and final states of the collisions states of the collisions

Neutron Production 400 MeV/n Carbon on Copper Pion Production 1 GeV/c/n Carbon on Be, C, Cu and Pn Geant4 6.2.p02 Binary Cascade Light Ions

Distribution of Rs Rs Distribution of Carbon Beams Carbon Beams R = ( σ calculate - σ measure )/ σ measure C 290M eV/n C 400M eV /n 200 Overestimate 200 100 100 % % o o R ati R ati Underestimate 0 0 -100 -100 0 20 40 60 80 0 20 40 60 80 Laboratory A ngl e [D egree] Laboratory Angl e [D egree] Iwata et al., Phys. Rev. C64 Target Materials pp. 05460901(2001)

Distribution of Rs Rs Distribution of Neon Beams Neon Beams N e 400M eV /n N e 600M eV /n 200 200 100 100 % % o o R ati R ati 0 0 -100 -100 0 20 40 60 80 0 20 40 60 80 Laboratory A ngl e [D egree] Laboratory Angl e [D egree] Iwata et al., Phys. Rev. C64 pp. 05460901(2001) Target Materials

Distribution of Rs Rs Distribution of Argon Beams Argon Beams A r 400M eV /n A r 560M eV /n 200 200 100 100 % % o o R ati R ati 0 0 -100 -100 0 20 40 60 80 0 20 40 60 80 Target Materials Laboratory A ngl e [D egree] Laboratory A ngl e [D egree] Iwata et al., Phys. Rev. C64 pp. 05460901(2001)

Neutron Yield Neutron Yield Argon 400 MeV/n MeV/n beams beams Argon 400 Carbon Thick Target Aluminium Thick Target T. Kurosawa et al., Phys. Rev. C62 pp. 04461501 (2000)

Neutron Yield Neutron Yield Argon 400 MeV/n MeV/n beams beams Argon 400 Copper Thick Target Lead Thick Target T. Kurosawa et al., Phys. Rev. C62 pp. 04461501 (2000)

Neutron Yield Neutron Yield Fe 400 MeV/n MeV/n beams beams Fe 400 CarbonThick Target Aluminum Thick Target T. Kurosawa et al., Phys. Rev. C62 pp. 04461501 (2000)

Neutron Yield Neutron Yield Fe 400 MeV/n MeV/n beams beams Fe 400 Copper Thick Target Lead Thick Target T. Kurosawa et al., Phys. Rev. C62 pp. 04461501 (2000)

Distribution of Rs Rs Distribution of for QMD and HIC Calculation for QMD and HIC Calculation (done by original author) (done by original author) Underestimate 100% -100% Overestimate R = 1/ σ measure x( σ measure - σ calculate ) QMD HIC Iwata et al., Phys. Rev. C64 Iwata et al., pp. 05460901(2001) Phys. Rev. C64 pp. 05460901(2001)

Fragmented Particles Fragmented Particles Productions Productions Si 490 M eV /n on H Si 490 M eV /n on C 1000 1000 on [m b] on [m b] 100 100 D ATA D ATA C ross S ecti C ross S ecti G 4 G 4 10 10 1 1 Al M g N a N e F O N C Al M g N a N e F O N C Parti cl e Speci es Parti cl e Speci es F. Flesch et al., J, RM, 34 237 2001

Fragmented Particles Fragmented Particles Productions Productions Si 453 M eV /n on A l Si 490 M eV /n on C u 1000 1000 on [m b] on [m b] 100 100 D ATA D ATA C ross S ecti C ross S ecti G 4 G 4 10 10 1 1 Al M g N a N e F O N C Al M g N a N e F O N C Parti cl e Speci es Parti cl e Speci es F. Flesch et al., J, RM, 34 237 2001

Wilson Abrasion & Ablation Wilson Abrasion & Ablation Model Model • G4WilsonAbrasionModel is a simplified macroscopic • G4WilsonAbrasionModel is a simplified macroscopic model for nuclear- -nuclear interactions based largely on nuclear interactions based largely on model for nuclear geometric arguments geometric arguments • The speed of the simulation is found to be faster than • The speed of the simulation is found to be faster than models such as G4BinaryCascade, but at the cost of models such as G4BinaryCascade, but at the cost of accuracy. accuracy. • A nuclear ablation has been developed to provide a • A nuclear ablation has been developed to provide a better approximation for the final nuclear fragment from better approximation for the final nuclear fragment from an abrasion interaction. an abrasion interaction. • Performing an ablation process to simulate the de • Performing an ablation process to simulate the de- - excitation of the nuclear pre- -fragments, nuclear de fragments, nuclear de- - excitation of the nuclear pre excitation models within Geant4 (default). excitation models within Geant4 (default). • G4WilsonAblationModel also prepared and uses the same • G4WilsonAblationModel also prepared and uses the same approach for selecting the final- -state nucleus as state nucleus as approach for selecting the final NUCFRG2 (NASA TP 3533) NUCFRG2 (NASA TP 3533)