My First Volume - 1/5

In this tutorial you will build a liquid hydrogen target and a paddle made from a custom scintillator material. You will use variations to study two options for paddle length. This could be done using a single perl script, however the code is organized in a “paddle” and a “target” script to give an idea on how to work with more complex geometries.

Pre-requisites

Tarball containing the material for this tutorial: myFirst.tar.

To unpack:

tar -xpvf myFirst.tar

MYSQL or TEXT?

Take a look at the file config.dat. Notice the entries that speficy the detector name, and the factory:

# Detector name and variation
detector_name: example
factory:       TEXT

The factory will select the format in which the geometry is saved. Here we will work in offline mode (TEXT) using a local database (a text file). If MYSQL was selected, the geometry would go in a MYSQL database. The detector_name is the name of the database. All volumes, materials, sensitivity definitions, etc are grouped under this name.

Variation

A variation of a detector is a different version of it. In this example we will create two variations: “short” and “long” to compare different detectors (short and long paddle).

Hierarchy

Take a look at paddle.pl, the file that builds the paddle.

The following lines of code define the volume name, its mother volume and a description of it:

$detector{"name"}        = "paddle_1";
$detector{"mother"}      = "root";
$detector{"description"} = "Example of paddle";

The position and rotation of a volume are relative to its mother volume. The rotation will happen before the position. “root” is the root volume.