Description of mMvdTrig

The calling sequence for this module (with links to the source code) is:

mMvdTrig dMvbRaw dMvcRaw dMvdTrigControl dMvdTrigPar dMvbSkev dMvcSkev

Calculate the multiplicity of inner shell and determine trigger condition.

On the first call, if the table is empty (zero rows) this module fills some parameters in dMvdTrigPar:
NHITMIN=2 -- the min number of "hits" to satisfy the "trigger",
THRESH_KEV=25. -- threshold in keV to consider a "hit"
OCC_CUT=0.45 -- above this occupancy, the "correlation" method of vertex finding will be used, below this occupancy the "pseudo-tracking" method will be used.

This module returns

dMvdTrigControl->itrig=1 if the number of hits in the inner barrel of the MVD is greater than dMvdTrigPar->NHITMIN
and
dMvdTrigControl->itrig=0 if the number of hits in the inner barrel of the MVD is less than dMvdTrigPar->NHITMIN
The number of "hits" is actually the number of "clumps" (calculated from dMvbSkev) of adjacent strips with signals larger than MvbSkev[i].skev > dMvdTrigPar->THRESH_KEV

This module was originally intended to provide a simple model for the level-1 trigger out of the MVD. However, it is not used seriously in the MVD code (and the threshold is set to require only two hits) and it not used at all by other parts of the PHENIX code (as far as I know). The most important parameter associated with this code is the OCC_CUT, which is used to choose the vertex-finding algorithm. However, this parameter could be sent externally.