The Cosmic Ray Energetics And Mass (CREAM) project will investigate ultra high energy (1012 to > 5 x 1014 eV) cosmic rays over the elemental range from protons to iron utilizing a series of Ultra Long Duration Balloon (ULDB) flights. The goal is to observe spectral features and/or abundance changes that might be related to a supernova acceleration limit. The measurements will be made with an instrument consisting of a sampling tungsten/scintillating-fiber calorimeter preceded by a graphite target with scintillating-fiber layers for trigger and track-reconstruction purposes, a transition radiation detector (TRD) for observing heavy nuclei, and a segmented timing-based particle-charge detector. A key feature of the instrument is its ability to obtain simultaneous measurements of the energy and charge of a subset of nuclei by the complementary calorimeter and TRD techniques, thereby allowing in-flight inter-calibration of their energy scales. The energy reach will depend on a series of ULDB flights of identical instruments: three flights will reach 5 x 1014 eV. The different flights can be carried out at essentially any latitude, including the polar regions of either hemisphere.
CREAM has been launched twice utilizing zero-pressure balloons (40M - L) in Antarctica, first in December 2004 and second in December 2005. It circumnavigated the south pole three times during the first flight, which set a flight duration record of 42 days. A cumulative duration of 70 days within 13 months was achieved when the second flight was completed in 28 days during two circumnaviagtions of the continent.
