This demo program computes the dose-depth profile of protons in water

-A water tub of dimenstions 5 x 5 x 30 cm in kept inside a world volume with a size slightly bigger than the water tub (factor 1.2)
-A scoring volume with a size similar to the water tub is also created with a 300 bins along z and 1 bin along x any y is created
-Protons are shot from one end of the water tub
- On a system where Geant4 is setup:
- Compile the code and run ./exampleB1 4 100 10000
- The above command will shoot 10000 protons of energy 100 MeV using 4 threads
- At the end of the run, the contents of the scoring volume are dumped to a file with a name energy-MEV-events-EVTS.txt
-- There is a file called dose-depth.py which can be used to plot the content of the output file to see the Bragg-peak.
-If you want to loop over many energies, then run ./exampleB1 4 100 200 2 10000:
-- The above command will generate a set of commands which you need to copy and paste in the terminal
-- This will generate dose-depth curves from 100 MeV to 200 Mev with step size of 2 with 10000 events for each energy

-Running without any arguments will open the interactive terminal which can be used to check the geometry.
-The data folder contains depth-dose curve for the range of energies relavant to proton therapy 
-The QBBC physics list was used to generate the data.