The SF Parameter Common Block

typedef struct SFPARAM_COM {
  int   num_iit,num_dim,num_lay,num_lpi,num_spl,num_ff;
  int   iit_threshold[3][MAX_IIT];
  float iit_gain[MAX_IIT];
} SFPARAM_COM;

       common/fgsfparam/fgsfparam_iit,fgsfparam_dim,fgsfparam_lay,
     &                  fgsfparam_lpi,fgsfparam_spl,fgsfparam_ff,
     &                  fgsfparam_iitthr,fgsfparam_iitg

The SF parameter common block contains the basic parameters which describe the geometry and configuration of the scifi detector.

num_iit is the number of image intensifier tubes, num_dim the number of different fiber projections (dimensions), num_lay the number of layers (or sections), num_lpi the number of layers attached to one IIT, num_spl the number of sheets in one projection of one layer. For the K2K SF detector these numbers are 24, 2, 20, 10, and 6. Software should not hard-code these numbers directly, but rather, reference this common block for future portability.

num_ff is the number of fiducial fibers in the EL mapping table, and this value may vary from run to run, if different tables are used.

iit_threshold contains three threshold parameters which describe how the image produced by that IIT should be treated while searching for hits. The first value contains an ADC threshold required for acceptance. Any pixel with an ADC value less than this threshold will be removed from the image. The second value contains the minimum number of pixels in a cluster, and the minimum hit weight for a fiber to be considered truly hit.

The final value, iit_gain, is a floating point number which can be used to scale the relative brightness of pixels recorded on one IIT to an equivalent value for another IIT.