The interaction of an ion beam with a foil or gas stripper is known to affect its charge state distribution.
TARDIS has been developed for the purpose of calculating the distribution of the expected charge states after such a stripping point and aims to aid with optimal charge selection in relevant studies.
As input to the program the user can define the following:
- The bean characteristics:
- the ion atomic number Z,
- the respective mass, m, (in amu),
- the beam energy, E, (in MeV),
- the initial ionization parameters of the beam,
- a multiplication factor for the result representaion.
- The stripping medium characteristics
- material type (gas or foil) and
- the atomic number Z of the material
The predictions are made with use of empirical formulas that follow the assumption that the charge state distribution can be approximated with a Gaussian distribution. Under this assumption, the mean charge state q_0 as well as the width d of the charge state distribution after stripping are calculated.
The formulas that are used in the program:
- the Nikolaev - Dmitriev formula (Foil stripping) - one of the best formulas for Carbon stripper foils, medium/high Z and few MeV/A
- Sayer's formula (Gas and Foil stripping) - appropriate for heavier elements
- Betz's formula (Foil stripping) - one of the best formulas for Carbon stripper foils, medium/high Z and few MeV/A
- Schiwietz - Schmitt formula (Gas and Foil stripping) - appropriate for elements between He - C. For the calculation of the qmean value Schiwietz's formulas for gas and foil stripping are used, while for the width calculation Schmitt's formula is used.
- The empirical formulas used in the code are available for download from the program.
- The outputs of the expected charge states calculations are presented in table format, which can be exported in Excel format (requires Microsoft Excel).
- A graphical representation of the expected charge states distribution after the stripping poing is also generated and can be downloaded as .png file.
- In the case that a formula doesn't support a combination of element and Energy values an error message appears on the respective table slot.
- The Schiwietz - Schmitt predictions are presented for 2 < z < 6 values, where it derives best results.
- If an error of "Missing assembly reference" occurs, go to Solution Explorer>Right-Click References>Add Reference...>Browse...>OxyPlot-2014.1.240.1\NET45>Select all .dll>Add
- Fits from:
- V. S. Nikolaev and I. S. Dmitriev, 1968, “On the equilibrium charge distribution in heavy element ion beams”, Physics Letters, vol. 28A, pp. 277-278
- H. D. Betz, 1983, “Heavy- ion charge states”, Academic Press, Applied Atomic Collision Physics (S. Datz, ed.), p. 1
- RO Sayer, 1977, "Semi-empirical formulas for heavy-ion stripping data", Rev. de Phys. App. 12 (1543)
- G. Schiwietz and P. L. Grande, 2001, "Improved Charge - State Formulas", Elsevier, Nuclear Instruments and Methods in Physics Research B 175 - 177, 125 - 131
- C. J. Schmitt, 2010, "Equilibrium charge state distribution of low- z ions incident on thin self- supporting foils", [PhD] Dissertation, Notre Dame, Indiana.
- Program developed by E. M. Asimakopoulou [Contact: emasi@kth.se]
- This program has been developed as part of the APAPES experiment
- Project Coordinator: Prof. Theo J.M. Zouros, Dept. of Physics, University of Crete [Contact: tzouros@physics.uoc.gr],
- http://apapes.physics.uoc.gr/
- Based on "Charge", program by Justin M. Sanders [Fortran] .