How the timeline is built....

Fisrt of all, 7500 events randomly chosen from the second file of each run are used to obtain the microvertex profiles. In particular, besides the ''ususal'' profiles you are used to see in ghost or in the beam spot page, ''centimeter profiles'' are produced. Those plots are filled according to the position of the hit.
Those plots are then fitted with a gaussian and a 2nd degree polynomial (see Fig. 1).

Remember that this is an approximation !

Then the values obtained from the fit are combined view per view (i.e the mean value is calculated) and finally rotated into the spectrometer reference frame.

Fig. 1

For an interesting timeline of SWIC values, refer to the SWIC timeline page

Last updated on 13-March-1997 by