Air Showers
What are the main components of an air shower?
Hadronic, Electromagnetic, and Muonic component
Why can't we observe cosmic rays directly?
Due to the deflection of Galactic and extragalactic magnetic fields as cosmic rays are charged particles
How can neutrinos help us detect cosmic ray sources?
Since neutrinos are produced from charged pion / kaon decays coming from hadronic interactions from sources, and they do not experience any deflections.
True or False: The fluorescence detector can be used during a full moon
False: The fluorescence light from the moon will smear the fluorescence yield of the air shower. They are conducted in moonless nights instead.
What is the "muon puzzle"?
The discrepancy between the number of muons from hadronic interaction models and observations (observations show less number than simulations).
What is the dominant emission mechanism for radio emission in air?
geomagnetic emission
What are the main candidate sources for cosmic rays below the knee?
Supernovae remnants, pulsar wind nebulae, stellar clusters, acceleration processes within the Galactic Center region
How can gamma rays be produced from cosmic ray sources?
Either through neutral pion decay or through synchrotron radiation / inverse Compton scattering / bremsstrahlung experienced by leptons generated through charged pion decay
What is the main mechanism used to detect neutrinos?
Cherenkov radiation coming from charged particles interacting with neutrinos
How does the GZK effect work?
How is Xmax related to the primary energy?
Logarithmically, due to Heitler model
True or False: Fermi II acceleration is the dominant acceleration process in SNRs
False: Fermi II acceleration is due to deflection by magnetic mirrors. Fermi I acceleration (or diffusive shock acceleration) is due to the repeated crossing of particles across the shock front.
True or False: Gamma rays are attenuated over large distances.
True: They are affected by the extragalactic background light
List all the detectors used in AugerPrime.
Water Cherenkov Detectors (WCD), Scintillators, Fluorescence detectors, radio antennas, underground muon chambers
What is the elongation rate, and how is it connected to Xmax?
Elongation rate is d Xmax / d (log E). It is an indicator of the multiplicity of high energy particles and the interaction cross section.
True or False: The Xmax of heavier nuclei is larger than those of lighter nuclei
False: Heavier nuclei produce showers higher in the atmosphere compared to lighter ones, thus yielding a smaller Xmax.
What does the Hillas criterion imply about the size requirement of UHECR candidate sources?
The Hillas criterion in EMax ~ Z B L, where L and B are the size and magnetic field of the source. For UHECRs at 10^20 eV or higher, the sources must be large and / or stronger magnetic fields. In particular, AGNs are much better candidates than SNRs.
Why are understanding neutrino oscillations important?
To understand the flavour of the neutrino at the source, we need to understand how they undergo flavour change as they propagate so that we can better interpret neutrino fluxes.
What are the major advantages with using radio for cosmic ray detection?
Cheap to build, 100% duty cycle, sensitive to shower development
For which showers is geosynchrotron emission important?
For very inclined showers
Why can muons also be used to distinguish the primary mass?
The number of muons increases with primary energy, and from the superposition model we can write the energy of heavier nuclei to be E0 / A.
True or False: We have an observation that UHECRs come from extragalactic origin.
True: the anisotropy map at intermediate energies from Auger indicate so.
Explain the Waxman-Bahcall bound.
A theoretical upper limit on the flux of high-energy neutrinos produced by cosmic ray interactions. Derived from observed from of UHECRs assuming a significant fraction of its energy goes to pion production.
List 5 notable experiments for gamma ray observations.
HESS, MAGIC, CTA, Fermi-LAT, VERITAS, LST,
List 3 future new experiments (not upgrades) for cosmic ray / neutrino observations.
Many examples, including : GRAND, GCOS, TRIDENT, P-ONE, DUNE, JUNO