The current web calculator for stopping powers is a real time implemetation of the "SRIM Module.exe" included in SRIM 2013 code (SRIM Tutorials), i.e., the current tables are those provided by SRIM code.
The following link give access to the Web Applications for the Electronic Stopping Power and Dose protons and ions:
How to use this Electronic Stopping Power Calculator and Ionizing Dose Converter
This tool calculates the Electronic Stopping Power curve for a particle incident on a material.
The input parameters and options for the tool are described below. When the input form has been completed, pressing the "CALCULATE" button will start the calculation and open the "Results" page (allow for pop-up in your browser settings). The result page will be also linked at the bottom of the calculator page.
In the present electronic stopping power to dose converter, the energy lost by the incoming particle is assumed to be fully absorbed by the medium - for instance, the medium is supposed to to be thick enough to fully absorb the kinetic energy of emitted delta rays - and the particle energy is almost constant while traversing the absorber.
- Incident particle (for Protons&Ions Calculator)
- Target material
- Calculator energy limits.
- Particle fluence for dose calculation.
In the Protons&Ions Calculator, using the pull down menu, the user can select the species of the incident particle, either a proton or one of the elemental ions.
In the section "Target Selection" it is possible to specify an User Defined target material or a predefined Compound material.
in the User Defined section individual elements can be selected as well as the composition of the target material choosing the number of elements in the compound. The required parameters for each element are:
- Atomic number (Z)/Chemical symbol
- Stoichiometric index or element fraction
Electronic Stopping Power for User Defined Compounds can be determined by means of Bragg's rule, i.e., the overall Electronic Stopping Power in units of MeV cm2/g is obtained as a weighted sum in which each material contributes proportionally to the fraction of its atomic weight. For instance, in case of a GaAs medium ones obtains (e.g., Eq. (2.20) at page 15 in [ICRUM (1993)]):
where and AGa [AAs] are the Electronic Stopping Power (in units of MeV cm2/g) and the atomic weight of Gallium [Arsenic], respectively.
As discussed in SRIM. (see help of "The Stopping and Range in Compounds" in SRIM-2013), the Compound Correction is usually zero for compounds containing heavy atoms, Al(Z>=13) or greater. All experiments with compounds such as Al2O3, SiO2, Fe2O3, Fe3O4, SiC, Si3N4, ZnO, and many more, show less than 2% deviation from Bragg's rule which estimates the stopping by the sum of the stopping in the elemental constituents. That is, the stopping in Al2O3 is the same as the sum of the stopping in 2 Al + 3 O target atoms. For these compounds there is no need for a Compound Correction. This correction should be accounted for in compounds containing mostly H, C, N, O and F for ion stopping below 2 MeV per atomic mass unit and is negligible above 5 MeV per atomic mass unit. In the current calculator, no correction is applied for target atoms lighter than Al. Further details are available at SRIM Compound, and SRIM Compound Theory.
In the Compoud section it is possible to select a predefined compound including the SRIM compound corrections in the stopping power calculation.
For instance, in the following plot, it is shown the percentage difference of the stopping power of H2O (selected as User Defined material) and Water_Liquid (selected as a Compound) as a function of the incoming proton energy in MeV:
This section define the energy limits of the calculation, and the following parameters will be defined:
- Minimum Energy of the incident particle
- Maximum Energy of the incident particle
The output table will contain 20 fixed values for each decade within the above selected range.
Moreover a text box is provided for entering additional energies. The input format is one energy per line; it is also possible to copy and paste energy values.
Particle Fluence for Dose Calculation
Here has to inserted the particle fluence to be used to obtain the corresponding deposited Dose.
The result page contains the input parameters, the Electronic Stopping Power curve and the result table, which includes the Ionizing Dose (in [MeV g-1] and [Gy]).