Last update: 29 March 2000
ACCESS - Advanced Cosmic Ray Composition Experiment for the Space Station
ACCESS is a mission to address several of the most important questions
currently open in cosmic ray physics. It will measure the energy spectra
of individual elements from hydrogen to iron in cosmic radiation up to
energies of approximately 10^15 eV. The data will permit a measurement
of the elemental composition of cosmic radiation close to
the theoretically derived limits for efficient supernova acceleration
(~ Z x 10^14 eV). It will also allow a measurement of the energy dependence
of the flux ratio of the secondary products of nuclear interactions to
primary cosmic ray elements, giving us clues as to the energy dependence
of the loss of galactic cosmic rays, allowing better modeling of the initial
fluxes.
These results will provide a test for supernova shockwaves as a possible
accelerator mechanism for nuclei. By measuring the flux of rare heavy nuclei (up to Uranium)
ACCESS will also provide clues as to the source of cosmic nuclei (e.g. existing
ionized particles from stellar winds or interstellar material bound up in
grains). A possible additional benefit would be if some directional dependence
could be found for electrons at energies in the TeV range.
ACCESS will be mounted on the International
Space Station (ISS) as an attached payload for a three year exposure.
The ACCESS baseline is
composed of three modules: (1) an Ultra Heavy (UH) nuclei module, (2) A Transition Radiation Detector (TRD)
module, and (3) a calorimeter.
The UMD ACCESS group is to
simulate and optimize a calorimeter for ACCESS [NRA-97-13-oss-013 ABSTRACT]. The ACCESS calorimeter
will need to measure the energy of an incident particle with adequate
resolution. It should have as large a geometric acceptance as possible to
collect the largest data sample possible. A 'tracking' capability will aid
in charge measurement by a silicon array or other charge measurement device.
An experimental
model based on GEANT code is being developed at UMD to trace cosmic ray
particles and their ensuing cascade through the full Calorimeter system. A
simulated event display shows the cascade (View 1 and
View 2) and the
detector response simulated in this process.
On-line Data Sets and Services(UMD)
- Design Concept
- Configuration Optimization of ACCESS Calorimeter
- Monte Carlo Simulation Information
Meetings & Presentations
Relevant ACCESS Links
Other Useful Web Resources
If you have any questions or comments, please write to
WebMaster.