QFND: Calling the QFNDIP package

The QFNDIP package of D. Brown et al. is described in the ALEPH Note 92-047, PHYSIC 92-042. It performs a precise determination of the interaction point on an event-by-event basis. It needs the beam constraint from the event-chunk beam position computed in the routine QFGET_BP (see sec. 6.4).

All necessary input banks are read by ALPHA at initialisation time. The results of QFNDIP are available as the main vertex variables QVX, QVCHIF and QVEM described in sec. 8.4 on p.  .

You should NOT call yourself neither QFGET_BP nor QFNDIP. QFGET_BP is called automatically for each event; QFNDIP is called when you put the QFND card.