A report on the BV position scan done 1995-May-02 is available here.
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To move the counter, use the program evbv. The program has to run on the data acquisition computer and the data acquisition system has initialized.
The readout of the position of the counter is done by a CAMAC ADC, which is read-out by the data acquisition system at the begin and end of spill events.
In addition to the readout through the DAQ, the position of the counters is stored in the map manager file evbv.map by the evbv program each time the counter is moved.
The EV/BV hits are unpacked into the GROUP_TRIGGER_TDCS and GROUP_VETO_BITMAP data group.
The EV/BV geometry package provides information about the position, size and shape of the EV/BV counters on a per-run basis.
To access this package, evbvGeom.h has to be included.
The package provides the following functions:
evbvGeom_getGeometry(...) will initialize the EV/BV geometry data structure
with the size and position of the counters at a given time.
Time instead of run number is used because the counter position information stored into the map manager by the evbv program is indexed by time. A work-around is possible because the event headers contain the time when the event was taken. This time can be used to load the correct EV/BV position.
The call returns -1 in case of failure and diagnostics are
printed to stderr
evbvGeom_setEncoders(...) calculates the position of the counters
given the X and Y position encoder values.
evbvGeom_setPositionXY(...) can be used to explicitely set the counter position
in X and Y.
evbvGeom_checkHit(...) takes the EV or BV geometry structure,
a track position at the counter's face and determines if this track will make
a hit in the corresponding counter.
//CO 11-Nov-1994