Ultra high energy cosmic rays and LHCf data
The origins of the cosmic rays with energies above 10^18eV
(UHECRs) have remained a persistent mystery for decades.
To study the acceleration mechanism and find the UHECR sources, one
must make careful measurements of the energy
spectrum, the composition and the arrival directions.
Telescope Array (TA) is specifically designed to measure these UHECR
properties precisely.The energy spectrum shows
the “ankle” structure around 10^18.7eV.At 10^19.75eV, there is the
second bending point where the UHECR flux starts
to decrease.The composition analysis using the longitudinal
development measurement shows that proton is dominant
above 10^18.2eV. Observed arrival direction shows no apparent anisotropy.
For the interpretation of cosmic ray air shower observations, the
knowledge of hadron interaction model is essential.
The Large Hadron Collider forward (LHCf) experiment measures neutral
particles emitted in very forward angle region
of hadron-hadron collisions at LHC. Knowledge of the forward particle
production is expected to improve the hadronic
interaction models used in the interpretation of cosmic-ray air shower
In this talk, I will present the latest results of TA experiment and
the problems of air shower measurement results.
The present status of the study of air shower phenomena using LHCf
recent results will be also presented.