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Detector Clusters

These sub-event clusters of parameters are defined to be sets of parameters that naturally occur together with a very localised timing relationship. A cluster may be one or more parameters from one detector or a group of similar detectors.

For example, the many phase1 Ge detectors at the target position can be considered as a cluster. They will fire within one event with a small time spread of tens of nanoseconds, and each detector has the same set of parameters associated with it.

The first processing task will take the input data blocks and search them for defined clusters. Parameters in the data stream that are not allocated to clusters will be discarded. Clusters will only be accepted if sufficient parameters have been found within the defined time interval.

Statistics and histograms of accepted/discarded parameters and clusters are provided for diagnostic purposes.

The accepted clusters will be output as buffered records to feed to the event determination code.

Cluster Setup

The first setup task is to associate the hardware ADC channels with particular detector parameters. This will be a lengthy operation every time the detector configuration changes significantly.

The mapping of VXI ADC board and channel to ADC label is calculated automatically ... 

Label = (Board_Number)*32  +  Channel_Number

The GUI will present a list of ADC boards and associated channels for the user to assign to particular parameters within the defined set of clusters.

The required set of clusters is chosen from a menu listing all the available cluster types. Each cluster type is defined by a template file.

Each parameter within a cluster type will have a fixed name that describes its functionality. The GUI for a parameter will show its name, its hardware board/channel name, and two flags. These flags will define whether the parameter is to be histogrammed and whether the parameter is required or optional.

The chosen cluster will need to be given a unique user-provided name. This name will, for example, be used to automatically generate histogram names relating to the cluster. For example, MWPC.dE may be the generated name for the histogram if the histogram-required flag is ticked for the energy-loss parameter of the MWPC cluster.

Each cluster type will have further sections describing any specific actions defining cluster acceptance, and its coincidence window width.

It will also be possible to define some particular 2D histograms. These may be derived from 2 in-cluster parameters, or from one in-cluster parameter and one external well-defined parameter.

Cluster Actions

Actions are defined to be cluster-specific routines that perform operations such as parameter and cluster acceptance tests and possibly cluster-specific histogramming functions (e.g. TACs).

There will be a set of default routines built in to the code. If particular functions are not specified for a cluster, then the default action routines will be executed.

For example, the default cluster acceptance routine will only check the time range specified for the cluster.