Starcheck detector response

With the Friday Morning Talk out of the way, we can now focus on other stuff, such as Starcheck response characterization.  Previously we compared non-rotated and rotated Starcheck profiles to get a feeling of uniformity.  Now we put it in a more rigorous test, by scanning a dose wedge with Starcheck.  Mounting starcheck on a Velmex linear stage, we move the profiler 9mm between successive scans.  The result is 23 scans, which can be used to link detectors on a line to central detector, as they are measuring the same dose.  The data points are 3 detectors apart, except for the central detector, which is 6mm away from its neighbours.  This exception actually caused me fair bit of grief in trying to figure out what's wrong with the parsing code.  After adjusting the code, we have a comparison of 22 detectors with the central detector.  Note that a systematic trend can be observed, with the edge detectors reporting lower dose than central detectors.  This may be attributed to the fact that for edge detectors, when they are at the beam axis, the central detector is at the edge of field.  Since Starcheck uses only the central detector for absolute dose measurement, a change in beam quality as we move across the wedge profile would cause a change in charge to dose conversion coefficient.  With that in mind, we note that detectors in the central 10cm are within 1%, which is within the manufacturer's specification.