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KaliVeda
Toolkit for HIC analysis
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KaliVeda
Toolkit for HIC analysis
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Each detector has an associated list of signals which may be DAQ parameters, the result of some calibration procedure, or derived from a mathematical combination of existing parameters:
The value of any signal can be retrieved using its name:
If the signal in question is not defined, this method returns 0. You can test if a given signal is defined for a detector using:
For more information on these methods, see the KVDetector class reference.
The base class which handles detector signals is KVDetectorSignal. As shown below, there is a family of related classes which have very similar behaviour which handle specific types of signals:
New signals can be defined and added to detectors using any mathematical expression involving known signals. For example, in order to define the ID_CSI-1111-VARX signal shown in the previous example above, you would go about it this way:
Note that such signal expressions may be added automatically when an identification telescope is initialised with an identification grid which uses such an expression as either its VARX or VARY coordinate (see Particle identification chapter).
The method KVDetector::AddDetectorSignalExpression() returns false if there is a problem with the expression (no known signals). In this case no new signal is added to the detector.
Detector signal expressions are handled by the KVDetectorSignalExpression class.
Calibrated signals (handled by the KVCalibratedSignal class) are added to detectors when a calibration is available for a given run of a dataset (experiment). In order to add calibrations to a dataset, it needs to have a file [array_name].CalibrationFiles.dat which contains the names of files containing different calibrations for different detectors and different runs.
Each of these files should have the same basic structure:
This file defines how to transform the PG signal of the listed detectors into a new Volts signal. A calibration basically defines how a new calibrated signal is generated from an existing input signal using a KVCalibrator or derived class:
The "transfer function" of KVCalibrator (defined by the func parameter in CalibOptions above: see below) can be any function which can be written as a string in the format understood by TF1 or TFormula. The 'input signal' can of course itself be the result of a calibration procedure, i.e. it can be a KVCalibratedSignal, or indeed any other signal derived from KVDetectorSignal (see diagram above).
The file must define at least the input and output signals using their names (SignalIn and SignalOut parameters above) and the type of the calibration (used for naming objects). If a specific KVCalibrator-derived class is to be used in order to perform the calibration i.e. one of the classes which appear in the following diagram:
then a CalibClass parameter can be used to specify which one. However, this is not the name of a class: it is a name of one of the plugins defined in order to extend the KVCalibrator base class. In order to know which plugin name corresponds to which class, you can use the following two methods:
The order of the class/plugin names in the two lists is the same. In general, the plugin name is just the class name minus the KV prefix.
The CalibOptions parameter may be used if required to supply any additional information needed to set up the calibrator object as you wish. If and how to use this parameter depends on which class you are using: look at the class reference guide to see if the class has a specialised version of the KVCalibrator::SetOptions() method (see for example the KVCalibrator::SetOptions() method for the calibrator used in the example above).
Once defined, the calibrated signal values are obtained in the same way as any other, using the KVDetector::GetDetectorSignalValue() method:
If a calibration requires further parameters in order to be used correctly, they can be passed to this method as a string containing name=value pairs. An example is the Light-Energy calibration for CsI detectors, which depends on the identification of the particle for which the energy is to be calculated:
Any such required extra parameters will be defined in the Compute method of the calibrator (for example, see KVLightEnergyCsI::Compute()).
Another use for the parameter list is to change the value of the input signal used by the calibration: if a parameter INPUT is given in the list, its value will be used instead of the current value of the input signal:
By default a detector is considered to be calibrated i.e. the method KVDetector::IsCalibrated() returns kTRUE{.cpp} if it has a signal defined called Energy. However this behaviour may be modified in specific daughter classes.
Given the situation in the previous examples i.e. where a detector called SI_0801 has one or more calibrations available, it is possible to "backtrack" from one or other final output values and calculate what would be the input, i.e. the calibration can be inverted, either partially or entirely:
1.9.8