The ATIC project is an international collaboration of researchers, who are building an experiment for long-duration balloon flight to investigate the energy spectra of Galactic Cosmic Rays in the ultra-light energy (>1012 eV) regime. The goal of this research is to answer the long-standing question about the “cosmic accelerator” which produces cosmic ray particles at energies 1000's of times larger than the biggest accelerator machines (e.g. CERN) on Earth.

Cosmic rays are the only sample of matter from distant regions of the Calyx, which can be directly observed by experiments near the top of the Earth’s atmosphere. In particular, the ATIC investigation, and the results have implications for particle acceleration in supernova remnants or other exotic objects, transport of particles through the interstellar medium and the nature of the cosmic ray sources.
ATIC is a tracking, ionization calorimeter instrument that has been built by researchers from the US (SU, LSU, UMD, NRL), Russia (MSU - V. Zatsepin and M. Panasyuk), Korea and Germany. It consists, from the top, of scintillator strip horoscopes within an inert carbon matrix, built by SU and LSU, and a Bismuth Germinate scintillating crystal calorimeter, built by LSU. An incident particle has its charge measured by the Si-matrix, its trajectory determined by the scintillator hodoscopes and its energy measured by the calorimeter from the cascade developed in the detector. The charge, energy and direction provide the raw data needed for this investigation.

The explosions of massive--Suprnovae--leaves violent, fast expanding, remnants which are believed to be the site of the “cosmic accelerator” which works via the action of magnetic fields at the expanding shock front. Such and acceleration model predicts a change in the energy spectrum of the elements, starting with Hydrogen (charge = 1), then Helium (charge = 2) and progressing to heavier nuclei. ATIC is designed specifically to look for such changes in the hydrogen, helium and heavy element spectra.
The ATIC payload weighs about 1360 kg, is contained within a pressurized gondola shell and consumes about 400 watts of power, provided by two panels of solar cells. To make the needed measurements of these rare, ultra-high energy particles, the ATIC balloon payload must be flown on at least four long-duration flights of 10 days each, i.e. around-the-world either in the northern or southern hemisphere. ATIC is scheduled for a test flight in spring 2000 to be followed by long-duration flights in each of the following years, as permitted by the ballooning schedule. From these flights will emerge a new understanding of particle acceleration in Supernova remnants and my lead to new techniques for other investigations.