# Session 2 : Exercise – 2015

To get the environment setup called automatically when a new terminal is open, you can add the commands for this setting in your login script, which is in our case in `\$HOME/.zshrc` file. Open this file in your editor and add the following lines:

```# Geant4 environment cd /usr/local/bin . geant4.sh cd```

Exercise 2a:

The picture shows geometry which will be implemented in this session.

• Inspect the code of the implemented geometry and modify materials to correspond to the geometry description below. The code already present describes the geometry of the first arm detector.
• Identify the code used for printing all materials.
• Implement geometry of a second arm described below.
• Get inspired by the code already present
• Proceed step by step. After adding each piece of geometry, recompile and test your application with visualization.
• Note that the Second Arm detector has a similar components as the First Arm detector.

Exercise 2b:

Explore implemented geometry:

• Check your geometry with geometry tree browser and with tracking geantinos with tracking verbose level=1

• Material ` galactic(vacuum) ` defined using NIST manager
• World volume
• represented as a box of `hx=10.*m, hy=3.*m, hz=10.*m`
• of `Air` material
• Tube volume
• of a tube shape with `rmin = 0.*m, rmax=1.*m, hz=1.*m`
• of `galactic (vacuum)` material
• First arm detector:
• represented as a box of ` hx=1.5*m, hy=1.0*m, hz=3.0*m `
• of ` Air ` material
• placed in `-5.*m `in z-direction (in front of `Tube` (in blue colour).)
• including:
1. 5 Drift chambers (in green colour)
• of a box shape with `hx=1.*m, hy=30.*cm, hz=1.*cm`
• of `Argon gas` material
• placed along z-axis with a distance of `0.5*m` from each other with the middle one in the center of the parent volume
2. Wire plane
• of a box shape with `hx=1.*m, hy=30.*cm, hz=0.1*mm`
• of `Copper` material
• placed inside each drift chamber in its center.

Geometry to be implemented:

• Add following materials (using NIST manager):Argon gas (`G4_AR`), CsI (`G4_CESIUM_IODIDE`) and Copper (`G4_Cu`) and update materials in First Arm detector
• Second arm detector
• represented as a box of `hx=1.5*m, hy=1.*m, hz=3.*m`
• of `Air` material
• placed in `5.*m` in z-direction (behind `Tube` (in blue colour)).
• Including:
1. 5 Drift chambers (in green colour)
• of a box shape with `hx=1.5*m, hy=30.*cm, hz=1.*cm`
• of `Argon gas` material
• placed along z-axis with a distance of `0.5*m` from each other with the middle one in the center of the parent volume.
2. Wire plane
• of a box shape with `hx=1.5*m, hy=30.*cm, hz=0.1*mm`
• of `Copper` material
• placed inside each drift chamber in its center
3. EM calorimeter (in yellow colour)
• of a box shape with `hx=1.5*m, hy=30.*cm, hz=15.*cm`
• of `CsI` material
• placed at `2*m` in z-direction from  the center of its parent volume (Second Arm Detector).
4. Fill the EM calorimeter with `15*cm` layers along x-direction of the same material (CsI)

Solution: session2_solution.tar.gz