Electronic Stopping Power

Written by Casper Christensen, Computer Science, Aarhus University.

This app provides electronic stopping power data of fast ions in a wide range of targets. It is based on the open source libdEdx library, which is available on sourceforge.net.

Stopping power tables are stored locally on the phone, so all data are available offline, no network access needed. (USB memory access is needed for the data tables.)

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 app 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 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.