  This is a report on the findings of the SNR/cosmic-ray working group for the
white paper on the status and future of ground-based gamma-ray astronomy. The
white paper is an APS commissioned document, and the overall version has also
been released and can be found on astro-ph. This detailed section of the white
paper discusses the status of past and current attempts to observe shell-type
supernova remnants and diffuse emission from cosmic rays at GeV-TeV energies.
We concentrate on the potential of future ground-based gamma-ray experiments to
study the acceleration of relativistic charged particles which is one of the
main unsolved, yet fundamental, problems in modern astrophysics. The
acceleration of particles relies on interactions between energetic particles
and magnetic turbulence. In the case of SNRs we can perform spatially resolved
studies in systems with known geometry, and the plasma physics deduced from
these observations will help us to understand other systems where rapid
particle acceleration is believed to occur and where observations as detailed
as those of SNRs are not possible.
