Differences between POT/DST and Mini-DST

In addition to the absence of some information, other differences may be observed when using the Mini. The Mini-DST has limited precision, so some quantities will have slightly different values from those found when reading the POT or DST. Non-trivial differences are:

• FRFT/0 is generally not available on the Mini-DST.
• For ITC tracks, the z$\sb$0 error is limited to 25cm, which increases QBC2 substantially.
• If the total number of vertices is greater than 30, only the main vertices and the best V$\sp$0 vertices (ordered by chi-squared) up to a total of 30 will be available when reading the Mini-DST.
• Further, the V$\sp$0 quantities available are the result of swimming the tracks, and if greater precision is required, a refit must be performed. Infrequently, problems arise when the charge of fitted track (FRFT/2) is different from that of the original track used (FRFT/0), and hence the two V⁰ tracks appear to have the same charge.
• The chi-squared and NDF for the helix fit for charged tracks may not be the same as those found for the DST, but the chi-squared per NDF should be correct within the foreseen precision.
• The values of R2 and R3 are truncated in the range [-10.23,+10.23], but where there are indications of problems, the values are set to +1000.
• For old MINIs ( 8.6 and before ) with GAMPEK photons, only the presence of dead stories is recorded, not information for each storey. Hence DST1,2,3 of the variable KEGPQU are all 0 or all 1.