Aarhus Universitets segl


About dEdx.au.dk

This website provides a java-script front end to the libdEdx stopping power library. It is inspired by the ESTAR, PSTAR, and ASTAR libraries maintained by NIST, but extends them with additional stopping power libraries and material compositions.

The purpose of libdEdx is to give easy access to tables and stopping power algorithms, but not to experimental data.

Currently the following stopping power tables are available:

  • ICRU49 - equivalent to PSTAR for protons and ASTAR for helium ions, this table reflects the exact stopping power table as published by the ICRU.
  • ICRU73 - Lithium and heavier ions. An erratum was published later regarding stopping power for water (condensed and vapor) and nylon. This web interface provides data from the revised version of ICRU73.
  • MSTAR - Covers Lithium to Argon ions.
  • BETHE_EXT00 - an implementation of the Bethe-equation expanded to low energy. The algorithm used is very close to that used in the Monte Carlo particle transport code SHIELD-HIT. This algorithm is provided since it works for any material/projectile combination, but should be used with great care, as it occasionally can be very much off the experimental data. Known cases are N-ions on silver and Xe-ions on aluminium at low energies. See NIMB 312 (2013) 110-117. Thanks to Helmut Paul for pointing this out.

Many of the tables above provide only stopping powers for a limited amount of target materials. The backend library libdEdx contains material composition data for more than 270 compounds, following the ICRU material index, if a material is selected which does not exist for a given table, then Braggs additivity rule is applied. Braggs addititvity rule will only work, if all constituents are available in the stopping power list, which may not be the case.

The Bethe equation is implemented as a function and is not based on tabulated data, and is in principle working for any material and ion.

The backend libdEdx was tested against the tabulated data, and deviations are below 0.1%. However libdEdx is still under development and naturally, bugs and inconsistencies may appear. We do not claim any correctness of the produced results, any use of these data are at own risk.


When using libdEdx, please refer to:

Lühr A, Toftegaard J, Kantemiris I, Hansen DC, Bassler N; Stopping power for particle therapy: The generic library libdEdx and clinically relevant stopping-power ratios for light ions. Int J Radiat Biol. 2011 Jul 19. [Epub ahead of print]. doi:10.3109/09553002.2011.595877.

You are free to use libdEdx for your own online services, but you should then clearly mention that libdEdx was developed by the Aarhus Particle Therapy Group, and explicitly link to https://dedx.au.dk, and ideally including our logo.

If you use https://dedx.au.dk in publications, acknowledgement of the Aarhus Particle Therapy Group while referring to https://dedx.au.dk is appreciated.