Cosmogenic nuclide production in meteoroids and planetary atmospheres
Jason Hirtz
Space Research and Planetary Sciences, Physics Institute, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
CERN - 14 November 2019
Collaborator: Ingo Leya
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 1 / 19 CosmogenicOutline nuclides Modelling - Simulation Needs
1 Cosmogenic nuclides
2 Modelling - Simulation
3 Needs
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 2 / 19 Cosmogenic nuclides Modelling - Simulation Needs
Cosmogenic nuclides
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 3 / 19 Cosmogenic nuclides Modelling - Simulation Needs Cosmic rays
composition • Protons (∼ 90%) • Alphas (∼ 10%) • Others (∼ 1%)
98% < 20 GeV/Nucleon
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 4 / 19 Cosmogenic nuclides Modelling - Simulation Needs Cosmic ray induced reaction: Nuclear spallation
Spallation reaction
Spallation with numbers • Light projectile (p, π, α,...) • Heavy target (12C, 208Pb,...) • Kinetic energy around the GeV • Time scale: ∼ 10−22 − 10−20 s
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 5 / 19 Cosmogenic nuclides Modelling - Simulation Needs Cosmogenic nuclides applications
Dating techniques • 14C
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 6 / 19 Cosmogenic nuclides Modelling - Simulation Needs Cosmogenic nuclides applications
Dating techniques • 14C/C τ ∼ 103years • 10Be/14C τ ∼ 104years • 26Al/21Ne τ ∼ 106years • 40K/K τ ∼ 109years ...
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 6 / 19 Cosmogenic nuclides Modelling - Simulation Needs Cosmogenic nuclides applications
Dating techniques Isotope conditions • 14C/C τ ∼ 103years • Natural abundance low → resolve • 10Be/14C τ ∼ 104years production vs natural occurrence • 26Al/21Ne τ ∼ 106years ⇒ Order of magnitude of production: 104 atom g −1 year −1 vs N • 40K/K τ ∼ 109years a ...
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 6 / 19 Cosmogenic nuclides Modelling - Simulation Needs Cosmogenic nuclides applications
Dating techniques Isotope conditions • 14C/C τ ∼ 103years • Natural abundance low → resolve • 10Be/14C τ ∼ 104years production vs natural occurrence • 26Al/21Ne τ ∼ 106years ⇒ Order of magnitude of production: 104 atom g −1 year −1 vs N • 40K/K τ ∼ 109years a • Stable or half-life comparable to the ... event of interest
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 6 / 19 Cosmogenic nuclides Modelling - Simulation Needs Cosmogenic nuclides applications
Dating techniques Isotope conditions • 14C/C τ ∼ 103years • Natural abundance low → resolve • 10Be/14C τ ∼ 104years production vs natural occurrence • 26Al/21Ne τ ∼ 106years ⇒ Order of magnitude of production: 104 atom g −1 year −1 vs N • 40K/K τ ∼ 109years a • Stable or half-life comparable to the ... event of interest • Measurable
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 6 / 19 Cosmogenic nuclides Modelling - Simulation Needs Cosmogenic nuclides applications
Dating techniques Isotope conditions • 14C/C τ ∼ 103years • Natural abundance low → resolve • 10Be/14C τ ∼ 104years production vs natural occurrence • 26Al/21Ne τ ∼ 106years ⇒ Order of magnitude of production: 104 atom g −1 year −1 vs N • 40K/K τ ∼ 109years a • Stable or half-life comparable to the ... event of interest • Measurable • Theoretical understanding of production processes
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 6 / 19 Cosmogenic nuclides Modelling - Simulation Needs Cosmogenic nuclides applications
Dating techniques Isotope conditions • 14C/C τ ∼ 103years • Natural abundance low → resolve • 10Be/14C τ ∼ 104years production vs natural occurrence • 26Al/21Ne τ ∼ 106years ⇒ Order of magnitude of production: 104 atom g −1 year −1 vs N • 40K/K τ ∼ 109years a • Stable or half-life comparable to the ... event of interest • Measurable • Theoretical understanding of production processes
Limit: our imagination
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 6 / 19 Cosmogenic nuclides Modelling - Simulation Needs Observables
• Exposure age • Terrestrial age I Time since the end of the exposure • Cluster in cosmic ray exposure age I Most of the meteorites observed come from just a few major collisions I Very true for H-chondrite, 20% of stony meteorites • Erosion rate • Uplift rate, soil dynamics • Other...
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 7 / 19 Cosmogenic nuclides Modelling - Simulation Needs Method of analysis
Theoretical understanding of production processes
Modelling of cosmic ray effects • Cosmic ray fluxes (p and α) • Target characteristics • Physics ⇒ outputs
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Theoretical understanding of production processes
CosmicTransmutation - Geant4 (framework) - INCL (spallation model)
Modelling of cosmic ray effects Spallation simulation • Cosmic ray fluxes (p and α) • 10 MeV - 20 GeV • Target characteristics • DoF: hadrons (p, n, ∆ ,π, ...) • Physics ⇒ outputs
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 8 / 19 Cosmogenic nuclides Modelling - Simulation Needs Method of analysis
Theoretical understanding of production processes
CosmicTransmutation - Geant4 (framework) - INCL (spallation model)
2 major sources of uncertainties
Initial state Physics: Spallation • Irradiation flux • Direct production • Target size, shape • Neutron production • ... • Energy / Angular distribution
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 8 / 19 Cosmogenic nuclides Modelling - Simulation Needs Models better than experiments
Problem of experimental data • Measurements compared to standards (composition, half-lives) • Variation of standards (7% in 1997 on Ca and Fe) • Off set comparisons
Model often gives better results • Consistency between the various techniques • Stable bias (systematic errors)
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 9 / 19 Cosmogenic nuclides Modelling - Simulation Needs
Modelling - Simulation
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 10 / 19 Cosmogenic nuclides Modelling - Simulation Needs Spallation with INCL
Spallation simulation Use of elementary XS to develop Use of nuclear XS to control
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 11 / 19 Cosmogenic nuclides Modelling - Simulation Needs Cosmogenic nuclides with CosmicTransmutation
Observables • Cosmogenic nuclide production rates • Light particle fluxes (p, n, α)
Planets Meteoroids (asteroids, moons) • Planet size • Shape • Atmosphere size, composition, • Composition density profile • Size • Magnetic field
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Hadrons below 20 GeV
We have • Irradiation flux above Antarctica
Problem • The irradiation flux is not the same everywhere because of the magnetosphere
We would like • Irradiation flux at different latitudes
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Irradiation • 2 phases • Reverse kinematic calculations • Map of allowed trajectories (Longitude, Latitude, Zenith, Azimuth, Rigidity)
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 14 / 19 Cosmogenic nuclides Modelling - Simulation Needs Cut-off maps
Standard New considerations • Structure of the penumbra Consideration of focusing and dispersion Funnel effect
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 15 / 19 Cosmogenic nuclides Modelling - Simulation Needs Cut-off maps
Standard New considerations • Structure of the penumbra • Consideration of focusing and dispersion Funnel effect
Funnel
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 15 / 19 Cosmogenic nuclides Modelling - Simulation Needs Planet irradiation
• Large scale magnetic field
• Cosmic ray flux at the top of the atmosphere for different latitudes
• Cosmic ray flux in space (galactic/solar)
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 16 / 19 Cosmogenic nuclides Modelling - Simulation Needs Conclusion
Needs • Know the irradiation flux (proton, alpha) • Understand the physics
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 17 / 19 Cosmogenic nuclides Modelling - Simulation Needs Important measurements
Irradiation spectra • Proton and alpha fluxes below 20 GeV at the top of the atmosphere at different latitudes • Magnetic field Earth • Solar cosmic ray flux (absolute, variations)
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 18 / 19 Cosmogenic nuclides Modelling - Simulation Needs Important measurements
Irradiation spectra • Proton and alpha fluxes below 20 GeV at the top of the atmosphere at different latitudes • Magnetic field Earth • Solar cosmic ray flux (absolute, variations)
Physics: elementary reactions • 2.5-20 GeV (proton) • 20 MeV - 1 GeV with focus below 200 MeV (neutron)
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 18 / 19 Cosmogenic nuclides Modelling - Simulation Needs Important measurements
Irradiation spectra • Proton and alpha fluxes below 20 GeV at the top of the atmosphere at different latitudes • Magnetic field Earth • Solar cosmic ray flux (absolute, variations)
Physics: elementary reactions • 2.5-20 GeV (proton) • 20 MeV - 1 GeV with focus below 200 MeV (neutron)
Physics: particle-nucleus • 2.5-20 GeV (proton) • Double differential xs • 20 MeV - 1 GeV (neutron) • Backward neutron production • 0-20 GeV (alpha) • “Exotic” physics
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 18 / 19 Thank you for your attention
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 19 / 19 Backup
Backup
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 1 / 7 Backup Simple input - Irradiation flux
Only one input parameter to fully define proton and alpha spectra: The solar modulation parameter M
proton
2 −2.5 10−4×T −2.65 T (T + 2mpc )(T + 780 × e + M) Jp(T, M) = cp × 2 (T + M)(T + 2mpc + M)
alpha (new)
K 2 cα × T × (T + 2mαc ) Jα(T, K) = 2 −2.5 1.65+K (T + 700)(T + 2mαc + 700)(T + 312500 T + 700)
K = (1.786 10−3 × M) − 0.1323
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 2 / 7 Backup Cut-off effects
New effects • Modified irradiation flux • Modified ratio p/α particles
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 3 / 7 Backup Funnel effect
CosmicTransmutation vs CosmicTransmutation
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 4 / 7 Backup Magnetic field intensity
Observations • Higher magnetic field increases the particle flux at the poles (higher focusing)
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 5 / 7 Backup Test Funnel algorithm
Jason Hirtz Cosmogenic nuclide production CERN - 14 November 2019 6 / 7 Backup
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