The DFEF boards are the cluster finder boards for the Forward PreShower (FPS) detector. These boards each contain two large FPGAs which scan through the U and V fibers in each FPS wedge and report cluster counts at L1 and sorted, zero compressed lists of the clusters themselves at L2.
Each DFEF board has two LVDS outputs, one for each wedge. Normally the boards L1 records continously, but if the trigger framework issues a L1accept the boards send a L2 record and then return to L1 transmission. Currently the L2 functionality has not been implemented and dummy L2 records are sent in response to a L1accept.
In the spring of 2006 the DFEF hardware and firmware will be expanded to provide additional outputs which will send cluster information to the L1 Calorimeter Trigger (CalTrk) system. Each DFEF board will then have two LVDS and two SLDB (serial link daughter board) outputs. The exact format of this new SLDB data is to be determined...
The DFEF Technical Design Report is aviailable as DZERO note 4788.