Geometry objects

The parameters of geometrical properties of individual sensors are stored in Phat as objects of classes derived from the TPhSensor class. Different types of sensors are represented by objects of different class: TPhSpectSensor for sensors of spectrometer, TPhTOFSensor for sensor of TOF detector and so on. Phat defines also sets of groups of sensors by an object of class TPhSensorSet. A number of predefined TPhSensorSet objects is created when geometry is initialized. Sensors are grouped in subdetector, layer, plane and module object types, defined in header files of the corresponding classes (TPhSubDetector, TPhSensorLayer ...). A user can create any number of additional sets of sensors, that his analysis requires. Both sensors and sensor sets are geometrical objects. Their classes derive from TPhSensorNode class which in turn derive from TNode class that is used to specify position of the sensor in space and provides facilities to build a physical tree of unique connections between sensors and sensor sets. Within this tree, a connection means that the position of a given node (sensor) is given with respect to the parent node, so the position of the sensor in the main reference frame is defined by a full path of connections from a given sensor to a volume in a master reference frame. In Phat this volume is called MOTHER. A parallel tree of connections between sensors and sensor sets is built using objects of TPhSensorSet class. This class in addition to being able to participate in the tree of nodes, has also additional lists of sensors and sensor sets. Using them one can define a logical tree of sensor sets. The tree of sensor sets is built during initialization of the geometry. The pointer to the tree is stored in the object of TPhGeometry class. In addition to this link, the TPhGeometry object has two separate lists of all sensors and sensor sets for fast access to these objects by their name.

The tree of geometry objects can be either Print()'ed or viewed using TBrowser object. After reading in the geometry from the ROOT file, a geometry can be found in the Geometries subdirectory of the TBrowser canvas.