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Evidence for changing of cosmic ray composition between 10(17) and 10(18) eV from multicomponent measurements
Abu-Zayyad1, Belov, Bird
1High Energy Astrophysics Institute, University of Utah, Salt Lake City, Utah 84112, USA.
Physical Review Letters
|September 16, 2000
Summary
Cosmic ray composition shifts from heavy to light elements as energy increases between 10^17 and 10^18 eV. This study used the High Resolution Fly's Eye (HiRes) and MIA muon array detectors.
Area of Science:
- Astrophysics
- Particle Physics
Background:
- Cosmic rays are high-energy particles originating from outer space.
- Understanding cosmic ray composition is crucial for astrophysics and particle physics.
Purpose of the Study:
- To determine the average mass composition of cosmic rays.
- To investigate composition changes at energies from 10^17 to 10^18 eV.
Main Methods:
- Utilized a hybrid detector system combining the High Resolution Fly's Eye (HiRes) prototype and the MIA muon array.
- Measured the depth of shower maximum and muon density as a function of energy.
Main Results:
- Observed a transition in cosmic ray mass composition.
- The composition shifts from a predominantly heavy mix to a lighter mix with increasing energy.
Conclusions:
- The energy-dependent change in cosmic ray composition provides insights into their origins and acceleration mechanisms.
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