The DAQ::DDAS::DDASHit class provides
information about a channel from DDAS. DDAS events are comprised
of hits. Each hit provides data from a single crate/slot/channel
of the system. If the NSCL Event builder is used hits may be aggregated
into events based on a coincidence window on their timestamps.
Several methods allow you to retrieve data from the hit or hits that comprise an event. In addition, hit objects are copy-constructable and assignable. We'll only look at the most common methods you'll need to know. The remainder are described in the reference documentation.
const uint32_t GetCrateID();
Returns the number of the DDAS Crate from which the hit came. The crate number is assigned in the cfgPixie16.txt file used by the Readout program that read the hit.
const uint32_t GetSlotID();
Returns the slot number from which the hit was acquired. Slot numbers used by a readout program are described in cfgPixie16.txt as well.
const uint32_t GetChannelID();
Returns the ID of the channel from which the hit came. The hit origin is uniquely defined by the crate, slot and channel within the slot.
const double GetTime();
Returns the calibrated timestamp of the hit. The Readout software produces a timestamp based on the raw timestamp that has been converted to nanoseconds. This allows the comparison of timestamps across modules with different clock frequencies (if they have been synchronized).
Note that it is an integerized version of this calibrated timestamp that is passed to the event builder. This allows events to be properly built from a system with a heterogeneous set of digitizers..
const uint32_t GetEnergy();
Returns the energy determined by the digital pulse processing algorithm of the channel.
std::vector<uint16_t>& GetTrace();
Returns a reference to the trace data stored for the hit. Note that the contents of the vector should not be considered well defined if the channel has been programmed not to return traces.
These are the most commonly used methods. Note that the full documentation for this class is available in the reference section.
The remainder of this document describes frameworks that present vectors of hits to code that you right or, alternatively, provide configuration files that describe how a simplified bit of code should operate.