1. 11 Geant4 and the Next Generation of Space-Borne Cosmic Ray Experiments Geant4 Space Users Workshop Hiroshima, Japan 26-28 August, 2015 MS Sabra 1, AF Barghouty 2, LS Sparke 2, JH Adams 3, ML Cherry 4, and MJ Christl 2 (1) USRA/Astrophysics Office, NASA-Marshall Space Flight Center, Huntsville, Alabama, USA (2) Astrophysics Office, NASA-Marshall Space Flight Center, Huntsville, Alabama, USA (3) CSPAR, University of Alabama in Huntsville, Huntsville, Alabama, USA (4) Dept. of Physics & Astronomy, Louisiana State University, Baton Rouge, Louisiana, USA

2. 2 Way Points The science of cosmic rays (CR) what are they?; where do they come from?; how do we observe them? Direct vs. indirect measurement of CR Current and near future CR experiments on the ISS Emerging technology KLEM; NUCLEON mission Geant4 Validation of KLEM Charge and energy resolutions; needed energy regime Path forward “ direct ISS-borne measurement of CR elements at the knee”

3. 3 A Very Brief History of Cosmic Rays 1912 Victor Hess discovers “extra-terrestrial radiation” 1930s- 1940s Discovery of protons; secondaries; pions 1948 Discovery of helium and heavier nuclei (Z=28) 1960s Discovery of “ultra-heavy” (Z>28) nuclei; electrons and positrons (x-ray astrophysics) 1970s Discovery of isotopes 1980s Age of cosmic rays; ISM properties 1990s Discovery of antiprotons; ACRs; GCRs with ultra high energies 2000s Astrophysical source(s) properties AMS Experiment on Space Station 2010+

4. 4 CR near Earth: Observed Spectra A break in the spectrum (hadronic, muonic, e-m, and Cherenkov) attributed to still unknown astrophysical mechanism(s) or sources!

5. 5 CR near Earth: Observed Composition spallation products CR composition is altered from their source composition due to propagation in the interstellar medium (ISM) Mostly spallation reactions with the ISM’s protons producing secondaries like the light nuclei Li, Be, and B, and sub-Fe group These tell us much about the time CRs spend and amount of matter they meet in the galaxy since their synthesis and acceleration ?

6. 6 A Glimpse of Cosmic Rays Astrophysics Origin of cosmic rays: supernovae remnants & ISM matter explosive nucleosnythesis: H, He, and CNO burning cycles, e-, r-, and s-processes; nuclei heavier than Ni are unstable stable ones (e.g., Fe) can be accelerated Acceleration of cosmic rays: differentiation (ionization potential, volatolity); supernovae shock (energetic, diffusive); First-order Fermi acceleration (turbulence) Transport of cosmic rays: diffusive – tied to the galactic magnetic field propagation effects (re-acceleration; spallation reactions; radioactive decay…) Modulation of cosmic rays: cyclic (dynamically coupled to the heliosphere); minor energy loss Cassiopeia A SCO OB2

7. 7 Cosmic Rays & Dark Matter (?) - Electron source is within a kpc - ‘Standard’ model is unable to account for the electron excess - Electrons and positrons could be products of dark-matter candidates like the Kaluza-Klein particle (620 GeV) - Controversial!

8. 8 Direct vs. Indirect Measurement of GCR Direct measurement (balloon- borne or ISS borne): – is limited to < 10 15 eV (or PeV) with current technology where flux is flux is only ~ 1 per m 2 -sr-yr – needs large collection area plus extended exposure time – ISS borne AMS-02 experiment < 1 TeV – Planned ISS-CREAM is limited to – Balloon-borne < 1 TeV Direct measurement (balloon- borne or ISS borne): – is limited to < 10 15 eV (or PeV) with current technology where flux is flux is only ~ 1 per m 2 -sr-yr – needs large collection area plus extended exposure time – ISS borne AMS-02 experiment < 1 TeV – Planned ISS-CREAM is limited to – Balloon-borne < 1 TeV Indirect measurement (ground- based): – infers the energy and charge of primary CR using secondary products created in the atmosphere; – Extended air showers are simulated using codes such as CORSICA – Composition is inferred from the e-m and/or muonic component, or from the emitted light (Cherenkov or fluorescence light) – Interaction model dependent! Indirect measurement (ground- based): – infers the energy and charge of primary CR using secondary products created in the atmosphere; – Extended air showers are simulated using codes such as CORSICA – Composition is inferred from the e-m and/or muonic component, or from the emitted light (Cherenkov or fluorescence light) – Interaction model dependent!

9. 9 KLEM Geant4 Setup 

10. 10 S-Function vs. Energy per nucleon

11. 11 Remarks Cosmic rays; from an astrophysics perspective – truly multidisciplinary – evolving – threads many other disciplines Cosmic rays; from a physics perspective – Basic and applied processes: across decades in energy! – new phenomena across old and new regimes – new approaches and applications Cosmic rays; from (for) applications perspectives – Particulate-radiation environments – Space as well as terrestrial – Technology driving

12. 12 Where to go for more info. on Cosmic Rays…  NASA HQ and centers’ websites all have lots of information and leads; for example:  http://imagine.gsfc.nasa.gov/docs/science/know_l1/cosmic_rays.html  University physics, geophysics, astronomy… departments; for example:  http://www.srl.caltech.edu/  National laboratories; for example:  http://www.ngdc.noaa.gov/stp/SOLAR/COSMIC_RAYS/cosmic.html  Other space agencies; for example:  http://www.esa.int/esaSC/index.html  Professional societies for example:  http://cosparhq.cnes.fr/