How to create your GEAR XML steering file

This post is a small guide on how to create your own GEAR file with GEAR v0.12, the first with multi-module capabilities. I will include a code example for each section of the description.

The root element of any GEAR XML steering file is gear

Children of gear

The only element that are currently looked for in the first layer of the tree structure of the XML file are:

• global which can only contain the attribute detectorName which is a string that defines, guess what, the detector name.
• BField which define the magnetic field in the detector and contaon 4 attributes
  • type is a string which defines what implementation to use to create a megnetic field object. As of August 2009 the only value available for this field is ConstantBField
  • x defines the x component of the B vector (double)
  • y defines the y component of the B vector (double)
  • z defines the z component of the B vector (double)
• detectors which contain a list of detector elements that will be described later

The first example of the first layer of the XML tree is:

<gear>
    <global detectorName="MyExperiment" />
    <BField type="ConstantBField" x="0." y="0." z="4.0" />
    <detectors>
        [Put your detector list here]
    </detectors>
</gear>

Defining your detector

The only type of element that can be defined has child of a detectors element is a detector (notice the lack of s). Infact the detectors element is but a list of detector items.

Each detector has two mandatory attributes which:

• name which is a custom identifier for the particular detector
• geartype which defines the specific type of the detector. This parameter is a string that must correspond to one of the gear detector types. For the TPC this is TPCParameters

The elements that can be contained in a detector are detector-specific. In the following I will describe the parameters necessary to describe a TPC.

Let's now fill the example a little more:

<gear>
    <global detectorName="MyExperiment" />
    <BField type="ConstantBField" x="0." y="0." z="4.0" />
    <detectors>
        <detector name="MyTPC" geartype="TPCParameters">
        [Define your TPC here]
        </detector>
    </detectors>
</gear>

[TO BE CONTINUED]

-- StefanoCaiazza - 14 Aug 2009