2002-2003 Science Planning Summary

Aeronomy & Astrophysics

Dr. Vladimir Papitashvili
Program Manager

AB-143-O

NSF/OPP ATIC
Station: McMurdo Station
RPSC POC: Ron Nugent
Research Site(s): Williams Field

ATIC Long Duration Balloon Flight (Advanced Thin Ionization Calorimeter)
Dr. John P. Wefel
Louisiana State University Baton Rouge
Physics and Astronomy
wefel@phunds.phys.lsu.edu
http://atic.phys.lsu.edu/aticweb

Deploying Team Members: James H Adams . Mark J Christl . Mark D Cox . Cynthia K Ferguson . Opher Ganel . Randy E Gould . Clifford Granger . Douglas J Granger . T. G Guzik . Leonard Howell ,Jr. . Joachim B Isbert . Evgueni Kuznetsov . Alexandre Malinine . Douglas R Smith . Michael Stewart . John P Wefel
Research Objectives: The advance thin ionization calorimeter (ATIC) balloon experiment uses NASA’s Long-Duration Balloon (LDB) program for a series of antarctic balloon flights (each 10 to 14 days long). The goal is to investigate the composition and energy spectra of galactic cosmic rays (GCR) at the highest energies accessible from balloon platforms, the region up to ~1014 electronvolt (eV). If supernova remnants are, as widely believed, the cosmic accelerators for the GCR, it is in this high-energy region that researchers anticipate observing effects of the acceleration process.

The ATIC experiment, weighing 1,360 kg and consuming 400 watts of power, consists of three major detector systems: (a) a detector to measure the particle charge, (b) a three-layer, crossed scintillator strip hodoscope, interspersed within a carbon target, to measure the trajectory of the particle, and (c) a fully active bismuth germanate scintillation calorimeter to measure the energy of the hadronic cascade initiated by particle interactions in the carbon target. The individual detectors are read out with application-specific integrated circuit devices.

Previous pioneering experiments have indicated differences in the spectra of hydrogen, helium, and the heavier nuclei, leading to an energy-dependent composition. In addition, the “all-particle” GCR spectrum and composition, as measured by ground-based air shower arrays, show indications of changes in the energy regime approaching the well-known spectral “knee” at 1015-1016 eV. The researchers’ goal is to apply new experimental techniques to the study of these very–high-energy particles to verify previous reports and to search for the behavior expected from the supernova remnant acceleration process.


Field Season Overview:
The research team will be transported daily between McMurdo and Williams Field to support shift work and round-the-clock payload monitoring during assembly, testing and flight operations. A crane will be used for final assembly and transfer of the 1,360 kilogram payload to the launch vehicle. During the flight, the research team will control the balloon from an office at McMurdo Station using a TCP/IP (internet protocol) connection. Successful flights are determined by the following criteria:

- At least eight days duration, 14-30 days is preferable

- At least 110,000 feet altitude, over 124,000 feet is preferable

- Minimum requirements for communication with the payload is the transmission of commands and receipt of instrument status information. Ideally, the group will also receive event samples.

- Recovery of the on-board recorders

Recovery of the payload data recorders is essential since only a small fraction of the data collected can be transmitted. With this in mind, the payload has been designed for partial recovery of critical components if the full payload cannot be recovered.