History: Calibration Technique

This calibration is based upon the analysis of histograms containing the differences between neighboring bars of the tof variable and of the ypos variable. For example, one histogram used for the analysis would be the tof variable of detector N1-14 subtracted by the tof variable of detector N1-15, for a given event. By doing this iteratively all detectors then can have their overall offsets relative to a single detector, and are so aligned.

Currently, detectors in N1 all have offsets relative to detector N1-10. Then detectors in planes N2 - N4 all have offsets calculated relative to the corresponding detector in N1. For example, to get the offset for detector N3-11, the histograms for N3-11 - N2-11, N2-11 - N1-11, and N1-11 - N1-10 would be used. Doing this, all detectors in planes N1 - N4 (excluding the GLA detectors) are aligned with N1-10. Then a histogram is used get the relative offset between N4-10 and N5-14. From there, and by a similar iterative process, all detectors in N5-N7 are aligned with N5-14 and hence with N1-10. A similar process was being done for the GLA detectors, but since detectors in that plane were removed and added on a run by run basis, this was delayed until a database with detector status per run would be created.

{img src=http//:www.jlab.org/~mjona/CalibDescript.jpg width=400 height=600 align=center desc=Example link=www.jlab.org/~mjona/CalibDescript.jpg }