2000/03/31 by J. W. Fowler, J.W. Fowler, L.F. Fortson +10 · 2 citations
Medicine · Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Dark Matter and Cosmic Phenomena #Radiation Therapy and Dosimetry #astro-ph
paper · pdf · doi:10.1016/s0927-6505(00)00139-0
published as Astropart.Phys.15:49-64,2001 · 25 pages, 10 figures. Submitted to Astroparticle Physics
arxiv created 2000/06/22 · openalex publication_date 2001/03/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/29
The energy spectrum and primary composition of cosmic rays with energy between 3× 1014 and 3×1016\uniteV have been studied using the CASA-BLANCA detector. CASA measured the charged particle distribution of air showers, while BLANCA measured the lateral distribution of Cherenkov light. The data are interpreted using the predictions of the CORSIKA air shower simulation coupled with four different hadronic interaction codes. The differential flux of cosmic rays measured by BLANCA exhibits a knee in the range of 2--3 PeV with a width of approximately 0.5 decades in primary energy. The power law indices of the differential flux below and above the knee are -2.72±0.02 and -2.95±0.02. We present our data both as a mean depth of shower maximum and as a mean nuclear mass. A multi-component fit using four elemental species shows the same composition trends given by the mean quantities, and also indicates that QGSJET and VENUS are the preferred hadronic interaction models. We find that an initially mixed composition turns lighter between 1 and 3 PeV, and then becomes heavier with increasing energy above 3 PeV.