Geometry Configuration

The detector geometry in Windsurf is configured through JSON files, making it easy to modify without recompiling the code.

Configuration Files

Two main configuration files are used:

Geometry Configuration - Defines the physical structure of the detector - Specifies dimensions, positions, and rotations - Defines the hierarchy of volumes
Materials Configuration - Defines all materials used in the simulation - Specifies material properties and compositions

JSON Format

The geometry configuration uses a hierarchical JSON format:

{
    "world": {
        "name": "World",
        "material": "G4_AIR",
        "type": "box",
        "size": {
            "x": 2.0,
            "y": 2.0,
            "z": 2.0,
            "unit": "m"
        },
        "position": {
            "x": 0.0,
            "y": 0.0,
            "z": 0.0,
            "unit": "cm"
        },
        "rotation": {
            "x": 0.0,
            "y": 0.0,
            "z": 0.0,
            "unit": "deg"
        }
    },
    "volumes": [
        {
            "name": "Detector",
            "type": "cylinder",
            "material": "G4_Si",
            "radius": 5.0,
            "height": 10.0,
            "unit": "cm",
            "position": {
                "x": 0.0,
                "y": 0.0,
                "z": 0.0,
                "unit": "cm"
            },
            "rotation": {
                "x": 0.0,
                "y": 0.0,
                "z": 0.0,
                "unit": "deg"
            },
            "mother_volume": "World"
        }
    ]
}

Units

All dimensions in the geometry configuration can specify units:

Length units: “mm”, “cm”, “m” (default is “mm” if not specified)
Angle units: “deg”, “rad” (default is “deg” if not specified)

For shape-specific dimensions (like radius, height), you can specify the unit in two ways:

As a property of the vector (for position, size):

"position": {
    "x": 0.0,
    "y": 0.0,
    "z": 0.0,
    "unit": "cm"
}

As a direct property of the volume (for radius, height, etc.):
```
"radius": 5.0,
"height": 10.0,
"unit": "cm"
```

Rotations

Rotations are specified in the following format:

"rotation": {
    "x": 30.0,
    "y": 0.0,
    "z": 45.0,
    "unit": "deg"
}

Rotations are applied in the Geant4 sequence:

First rotation around X axis
Then rotation around the new Y axis
Finally rotation around the new Z axis

Cylinder Orientation

Cylinders in Geant4 are created with:

The circular face in the X-Y plane
The height extending along the Z-axis

This means that rotations will behave as follows:

X rotation: Tilts the cylinder around the X axis
Y rotation: Tilts the cylinder around the Y axis
Z rotation: Rotates the cylinder around its central axis (Z)

For detailed API documentation of the geometry parser, see API Reference.