Shower initiated Light Attenuated to the Space Telescope


This is a package of programs written in FORTRAN77 language to simulate both fluorescence and Cherenkov light produced by extensive air shower (EAS)  initiated by Ultra High Energy Cosmic Rays (UHECRs) hitting the atmosphere. The SLAST can be used for various studies of space telescopes potentials observing the light in the UV region. In few words, in the SLAST:

  • The Earth and the atmosphere are considered to be spherical. It implies that there is no limitation on the incident UHECR's angle.
  • There are various atmosphere profiles tabulated
  • The shower is developed according to GIL longitudinal parametrization.
  • Hillas parametrization of the electron energy distribution is implemented.
  • Fluorescent light is carefully simulated taking into account it's dependence on the electron energy and the shower age and the production height in the atmosphere.
  • Cherenkov signal is simulated taking into account the energy distribution of the shower's electrons.
  • The atmosphere absorbtion is taken into account in two ways: analytical calculation of Rayleigh and Mie scattering and LOWTRAN7.1 treatment (default)

Easy Guide:                              download SLAST manual 


The SLAST package is tested on many UNIX/Linux platforms. The current version is 1.1.

1. download the sources (tar.gz archive)

2. To access always the latest SLAST version use CVS checkout. To get an access to server please write an e-mail .  CVS WEB access is also possible.

2.The installation

1.unpack the package (under Linux: tar zxvf slast.v1.r1.compiled.Linux.tar.gz)

2.go to the SLAST directory "geninst" (it will take some time to compile the package and to compute all necessary things for the later event generation)

Note: First installation run takes around 10 hours of CPU computations (on 1 GHz clock), if you want to save your time, download two files lowtran.rwn and slast.hbk (gzipped) and put them into slast/aux directory. Then you can skip the installation step.

3.Event generation

1.edit datacards/datacard.exp (where "exp" stands for an "experimente you do, like euso) to

set up number of events, detector parameters, etc (each keyword is explained)

2. run "genevt exp" (where again "exp" can be "euso")

4. Output

is PAW Column Wise Ntuple stored at ntuples/euso/ (if you run with datacard.euso, date is the starting job date which makes ntuple name unique). The ntuple can be opened within the PAW with LREC 4096. CWN is a compact output with averaged over one Global Time Unit (GTU) number of photons.