In low energy runs, the VPD acceptance and efficiency becomes a potential issue. We are planning to develop a barrel TOF self calibration algorithm based on only the hits on the barrel trays (we call it non-vpd-start calibration). The calibration constant structures should be similar as the conventional calibration using vpd for the start time. But certainly the algorithm in applying these constants will be different. We thus need to introduce an additional flag in the calibration table to tell the offline maker to load the corresponding algorithm then. The proposed the change is on the vpdTotCorr.idl table. The current structure is like this:

struct vpdTotCorr {
  short tubeId;   /* tubeId (1:38), West (1:19), East (20:38) */
  float tot[128]; /* edge of tot intervals for corr */
  float corr[128];   /* absolute corr value */
};
 

We would like to add another short variable "corralgo", then the modified idl file should be like this:

struct vpdTotCorr {
  short tubeId;   /* tubeId (1:38), West (1:19), East (20:38) */
  float tot[128]; /* edge of tot intervals for corr */
  float corr[128];   /* absolute corr value */
  short corralgo;     /* 0 - default vpd-start calibration algorithm */
                             /* 1 - non-vpd-start calibration algorithm */
};
 

We will make the corresponding modifications to the StVpdCalibMaker and StBTofCalibMaker to implement the new calibration algorithm.