Advanced Composition Explorer (ACE) CRIS Level 2 Data

The Cosmic Ray Isotope Spectrometer (CRIS) on the Advanced Composition Explorer
(ACE) spacecraft is intended to be a major step in ascertaining the isotopic
composition of the Galactic Cosmic Rays and hence a major step in determining
their origin. The GCRs (Galactic Cosmic Rays) consist, by number, primarily of
hydrogen nuclei (~92%) and He nuclei (~7%). The heavier nuclei (1%) provide
most of the information about cosmic-ray origin through their elemental and
isotopic composition. The intensities of these heavy cosmic rays are very low
and progress in the past has been impeded by limited particle collection power,
particularly regarding individual isotopes. CRIS is designed to have far
greater collection power (~250 cm2*sr) than previous satellite instruments (<
10 cm2*sr) while still maintaining excellent isotopic resolution through Z=30
(Zinc) and beyond.

CRIS level 2 data is organized into 27-day time periods (Bartels Rotations -
roughly one solar rotation period). For each Bartels Rotation, the level 2 data
contains time averages of energetic charged particle fluxes over the following
time periods:

- hourly
- daily
- 27 days (1 Bartels rotation)

Currently, flux data are available for 24 elements, in units of
particles/(cm2*sr*sec*Mev/nucleon), in seven energy ranges. The energy ranges
are different for each element. The elements for which data are available are:

- B, C, N, O, F, Ne, Na, Mg, Al, Si, P, S, Cl, Ar, K, Ca, Sc, Ti, V, Cr,
Mn, Fe, Co, Ni

See:
http://www.srl.caltech.edu/ACE/ASC/level2/cris_l2desc.html