Working tasks

First step

Using the Basic_Simulation GEANT4 project, we wil generate the root files for the following configurations:

The reference configuration : just the water cube without any hole.
AirHoleInwater configurations with the different characteristics:
- Size : cube of 0.5 cm side
  - locations
    - In the beam direction every centimeter from the entrance edge of the water cube from 1 to 10 cm
    - the same but with center of the cube shifted by 1 cm in the X direction at Z = 7, 8, 9 cm
    - the same but with center of the cube shifted by 2 cm in the X direction at Z = 7, 8, 9 cm
    - the same but with center of the cube shifted by 3 cm in the X direction at Z = 7, 8, 9 cm

For each simulation, 1,000,000 carbon projectiles at 200 MeV/A will be sent.

Then, for each simulation, the following histograms will be build:

The N (=A - Z) versus Z plots of detected fragments
the energy distribution of each type of fragment (from neutrons to 7Li)
The Yp versus Xp plots for each type of fragment (from neutrons to 7Li)

Build an analysis that show the potential differences between "AirHoleInWater" configurations and the reference configuration (Water cube only).

Second step

Simulations

The first step has shown differences in the mean energy values when a air hole is inserted in the water volume. We will now check the sensitivity of these differences with respect to the air hole size. We will then generate the root files for these new configurations using the new Basic_Simulation version with the MaterialBoxInWaterBox detector class:

MaterialBoxInWaterBox
- Material : G4_AIR
- Location : in the beam direction at 1 cm from the entrance edge of the water cube
- Sizes :
  - 4 mm in the beam direction and 5 mm side in the other directions
  - 3 mm in the beam direction and 5 mm side in the other directions
  - 2 mm in the beam direction and 5 mm side in the other directions
  - 1 mm in the beam direction and 5 mm side in the other directions

Analysis

The main differences seem to appear on the energy distributions. In order to have a more sensitive test, we will build the ratio histogram which is the ratio of the energy histogram for one configuration to the energy histogram of the reference configuration.

R (E_{kin}/A) = \frac{Histo_{conf} (E_{kin}/A)}{Histo_{ref} (E_{kin}/A)}

These histograms have to be generated for each simulation configution with a air hole and for each type of fragment (from neutrons to 7Li)

Git Repository

The simulation root files obtained in the first step and the generated figures have been deposited in the git repository. As these files are quiet big and in binary formats, there are not supposed to be in the git repository. These file have to be copied in a separate directory and removed from the git repository.

Third step

Analysis

Rebuild the ratio histograms with an energy range from 0 MeV/A to 250 MeV/A. The ratio histograms can be obtained easily by using the Divide method of TH1 objects.

Common ROOT file directory

The directory /data/appli/Elena_and_Ancy has been created. The ROOT files produced by the simulations have to be moved to this directory. This will allow to read these files for the three of us.

Fourth step

Simulations

We will redo the same studies by changing the material of the material box to cortical bone (G4_BONE_CORTICAL_ICRP). Hence the following simulations should be runned:

MaterialBox configurations with the different characteristics:
- Material : G4_BONE_CORTICAL_ICRP
- Size : cube of 0.5 cm side
  - locations
    - In the beam direction every centimeter from the entrance edge of the water cube from 1 to 10 cm
- for the location at 1 cm from the entrance edge of the water cube
  - Sizes :
    - 4 mm in the beam direction and 5 mm side in the other directions
    - 3 mm in the beam direction and 5 mm side in the other directions
    - 2 mm in the beam direction and 5 mm side in the other directions
    - 1 mm in the beam direction and 5 mm side in the other directions
Reference configurations :
- run 4 simulations to check the errors due to the finite number of projectile (statistical errors)

For each simulation, 1,000,000 carbon projectiles at 200 MeV/A will be sent.

Analysis

The ratio of two histograms does not seem to be good enough to identify potential changes. We will then use another histogram with the following definition:

with hRef(i) the content of the i^{th} bin of the reference histogram, hTest(i) the content of the i^{th} bin of the tested histogram and hTestErr(i) the error of the i^{th} bin of the tested histogram, we will compute the quantity:

R_{sigma} (i) = \frac{hTest(i) - hRef(i)}{hTestErr(i)}

for each bin of the control histogram.

We will also use the Kolmogorov test and the Chi2 test provided by the ROOT framework which compute the probability that two histograms are similar.

Fifth step

Simulations

We will redo the same studies by using a different beam: a Spread Out Bragg Peak (SOBP) instead a monoenergetic beam. The SOBP beam consists of several beam energees with appropiates weights in order to obtain a flat dose deposit from 75 mm to 85 mm range. Ths General Particle Source (GPS) of GEANT4 has been used to set-up this beam configuration. It is defined in the runSOBP.mac macro file.

All the simulation performed with the monoenergetic beam have to be re-runned with this SOBP beam. As a reiminder, here his the list of simulations to be done:

Air hole
- Material : G4_AIR
- Size : cube of 0.5 cm side
  - locations
    - In the beam direction every centimeter from the entrance edge of the water cube from 1 to 8 cm
- for the location at 1 cm from the entrance edge of the water cube
  - Sizes :
    - 4 mm in the beam direction and 5 mm side in the other directions
    - 3 mm in the beam direction and 5 mm side in the other directions
    - 2 mm in the beam direction and 5 mm side in the other directions
    - 1 mm in the beam direction and 5 mm side in the other directions
Bone brick
- Material : G4_BONE_CORTICAL_ICRP
- Size : cube of 0.5 cm side
  - locations
    - In the beam direction every centimeter from the entrance edge of the water cube from 1 to 8 cm
- for the location at 1 cm from the entrance edge of the water cube
  - Sizes :
    - 4 mm in the beam direction and 5 mm side in the other directions
    - 3 mm in the beam direction and 5 mm side in the other directions
    - 2 mm in the beam direction and 5 mm side in the other directions
    - 1 mm in the beam direction and 5 mm side in the other directions
Reference configurations :
- run 5 simulations to check the errors due to the finite number of projectile (statistical errors)

Analysis

Run the analysis on the newly generated simulations. Plot the Kolmogorov test probability and the Chi2 test probability for the alpha's energy (Ek/A) distributions as a function of the material box location and as a function of the material box size.

Report

Start to think about the report. Define the outlines of the report.

Sixth step

Simulations

We want to study the modifications induced by a shift of the beam center position. The beam center position can be modified in the beamConfiguration.mac. The following simulations have to be runned:

Water phantom without air hole nor bone brick
Nb of projectiles : 1,000,000
SOBP beam
Beam positions
- X=0 mm, Y=0 mm
- X=0.5mm, Y= 0mm
- X=1 mm, Y= 0mm
- X=1.5 mm, Y=0 mm
- X=2 mm, Y=0 mm

Analysis

Replot the energy distributions by changing the number of bins to 50 (or even 25!).

For the Chi2 test, plot the evolution of the p-value with the changing material box position and the material box size in the Z direction.

Run the analysis on the newly generated simulations. Verify that no changes are seen on alpha energy distributions. Plot the Yp vs Xp histogram of the detected particles for each type of fragment (neutrons, protons, deuterons, tritons, ^{3}He, alphas, ^{6}Li, ^{7}Li) and build the R plots from these histograms.

Report

Complete the outines of the report. Think about the figures to include in the report.

Edited Nov 27, 2025 by CUSSOL Daniel