[NOTE: This special application of SRIM is included with more details in the file: “Help – TRIM Input.pdf” (pages 8-32 to 8-35), included in the SRIM download package. It is also included in Chapter 8 of the SRIM textbook.]
"SR Module.exe" is a small program (included in the SRIM download software) that can run under the control of other programs that needs stopping powers and ranges. When it is executed, it reads a control file and then outputs a new file containing stopping powers and ranges. This output can then be used by the calling program. Since it has no user interface, it is invisible to the user.
SR-Module uses the same controls as the "Tables of Stopping and Ranges" which can be called from the SRIM Title Page. When "Tables of Stopping and Ranges" is run, the Setup program creates a file called "SR.IN" in the SRIM directory. It then calculates the requested stopping powers and ranges and places them in a separate file in the directory "/SRIM Outputs".
To use SR-Module, first look in the SRIM sub-directory "../SR Module". You will find a program "SR Module.exe", and data files: SCOEF03.dat, SNUC03.dat and VERSION. The first two are datafiles for the stopping and range program and the third contains the current version of SRIM.
You will also find a copy of the control file "SR.IN". It contains information such as shown below.
The items in RED control the SRIM Calculation:
Table 8‑9 - File SR.IN controlling Stopping and Range Tables
SR Module reads this file and generates a file called "Hydrogen in Water_Liquid" containing the stopping and range of H ions into water from 10 keV to 10 MeV. The 16 lines of the above file are explained below:
1 Title line. Note that all numbers MUST use a period as a decimal point.
2 Comment describing the next input line.
3 Name of the Output File
4 Comment describing the next input line.
5 Ion Atomic Number and Mass
6 Comment describing the next input line.
7 Target Data: [Target is a solid or gas], [Target Density- g/cm3], [Compound Correction]
8 Comment describing the next input line.
9 Number of target atoms (up to 100)
10 Comment describing the next input line.
11 Tgt Atom #1: Atomic Number, Name, Atomic Mass
12 Tgt Atom #2: Atomic Number, Name, Atomic Mass
13 Comment describing the next input line.
14 Output Stopping Units (1-8) [see listing of units below]
15 Comment describing the next input line.
16 Ion Energy Range, keV, of output tables (2 numbers)
To understand the details of this file, go to the SRIM program "Tables of Stopping and Ranges" and read the various HELP files. Execute this SRIM program to calculate a new Table, and then exit and look at the file "SR.IN". You can copy this control file into the subdirectory "../SR Module" and then execute "SR Module.exe". You will find that it generates the same table, but with no input from the user. This new file will be saved into the current directory of "SR Module.exe".
In the input file, the next to last item is "Output Stopping Units (1-8)":
(1) - eV / Angstrom
(2) - keV / micron
(3) - MeV / mm
(4) - keV / (ug/cm2)
(5) - MeV / (mg/cm2) = keV / (ug/cm2)
(6) - keV / (mg/cm2) = eV / (ug/cm2) = MeV / (g/cm2)
(7) - eV / (1E15 atoms/cm2)
(8) - L.S.S. reduced units
When you produce the Tables, you specify the starting and final ion energy, but you do not control the spacing of the energy increments. However, you can generate stopping powers for any list of energies using "SR Module.exe" by using the following change to the above "SR.IN" file.
Line 15: ---Ion Energy : E-Min(keV), E-Max(keV)
Line 16: 0 0
Line 17: 1.02
Line 18: 2.55
Line 19: 3.98
Line 20: 0
(Additional Lines Omitted)
Line 16 used to contain the lowest and highest ion energies of SR.IN as shown in Table 8‑9. Now it contains " 0 0 ". This indicates that the lines following this line will contain a list of specific energies. Enter your list of energies (up to 1000) and terminate the list with a " 0 " as shown above. The list shown above will generate a simple Output File that will look like:
Ion = Hydrogen , Mass = 1.008
Tgt = H + O (Solid), Density = 1 g/cm3
Stopping Units = MeV/(mg/cm2)
Energy(keV) S(Elec) S(Nuc)
1.020E+00 1.751E-01 3.921E-02
2.550E+00 2.694E-01 2.391E-02
3.980E+00 3.264E-01 1.681E-02
The top four lines of this output file allow a check of the input values. Then there is a list with three values on each line: [Energy (keV)], [Electronic Stopping Power], [Nuclear Stopping Power]. This file can then be read into another program which requires stopping powers for specific ion energies.
The nuclear stopping powers of SR Module will be slightly different from those in the full tables since these are improved values which will be incorporated into SRIM. The Table SNUC03.dat contains individually calculated nuclear stopping powers for all possible combinations of ion/targets, i.e. it contains 92 x 92 individual nuclear stopping powers. The nuclear stopping used in SRIM is a scaled stopping power, often called "ZBL" in the literature. This approximation is quite good for the interaction of atoms of approximately the same mass. However, it is somewhat inaccurate for ion / target atoms with quite different masses, especially H or He ions. The values produced by the SR tables described above are quite good because they are specific for the ion/target atoms specified, and do not come from a “universal” formula.