This page is intended to keep the FPD L1 Trigger files, including segments definitions for single detectors, tracking and VHDL equations. The downloadable files are written in conformity with VHDL format  standards so they can be promptly used at  the trigger firmware simulation/implementation stages.

The files contained in this page may quickly evolve since this work is still under way.

In this section we give a brief description and provide links to the files containing the logic equations of the FPD L1 trigger. These files contain only the logic terms that define the trigger equations, written in accordance with the VHDL standard. The complete trigger files with the header definitions and declarations included are given in the next section .

These are the finer segments possible to be defined and correspond to 1/3 of a detector fiber, what is approximately 1/3*0.80 mm = 0.27 mm. This fine segmentation is needed to resolve proton/antiproton relative momentum loss (dp/p) at the order of ~ 0.005. Equations for the fine segments are given in the table below. 

We can also define coarser segments by logically adding fine segments. A wide segment 4 times wider  (4*1/3 of fiber) than the fine segments is defined and used to implement triggers for high transferred momentum (|t |>1 GeV/c) events, where dp/p resolution at the first level trigger is not a must. An excerpt is shown below: 

In this example, the wide segment is defined in terms of fibers, but it could be done from the fine segments, as well.  The files defining wide segments are included in the table below.

Detector View	Fine Segments	Wide Segments
U	segmentsU.vhd	wideSegmentsU.vhd
X	segmentsX.vhd	wideSegmentsX.vhd
V	segmentsV.vhd	wideSegmentsV.vhd

These equations apply to all FPD detectors, as the geometry is the same for all of them.

The segments need to be validated in order to reduce the amount of ghost hits due to noise or spourious hits in the fibers. This is achieved by using the sets of validating equations defined in the table below, which match U, X and V segments. Only U and V segments are validated. X segment information is necessary just to validate an U-V coincidence, not being carried out to the next stage of the FPD trigger chain. 

Finally, in the same table one can also find the trigger tracking equations that link hits (U-V points) in the first detector to hits in the second detector which comprise a FPD spectrometer.

Click in the  (for the DI spectrometer the symbol changes to U1/ U2 or V1/ V2 as specific equations for DI1 and DI2 have been created)  to download the equations.

In this section we provide links to the VHDL equations, which include the firmware structure that allows their implementation using the Virtex family FPGA on the DFE Wide Daughter Board.

The L1 Trigger top level diagram for the dipole (DI) spectrometer is shown below. The diagrams for the other FPD spectrometers will be similar, only the number of files needed to implement each specific task (segments and trigger files) changing from one to another.

The files needed to implement each of the three flavors (PU, PI and DI) are given in the following table. (by the time being, there are links only to DI files).

Spectrometer Flavor	Spectrometers	Segments Files	Trigger Files
DI	DI	SEG FINE DET 1 SEG WIDE DET 1 SEG FINE DET 2 SEG WIDE DET 2	L1 TLOW XLOW L1 TLOW XHI 1 L1 TLOW XHI 2 L1 TLOW XHI 3 L1 TLOW XHI 4 L1 TLOW XHI 5 L1 THIGH
PI	PI,PO,AU,AD	SEG FINE DET 1 SEG WIDE DET 1 SEG FINE DET 2 SEG WIDE DET 2	L1 TLOW XLOW L1 TLOW XHI 1 L1 TLOW XHI 2 ... L1 THIGH
PU	PU,PD,AI,AO	SEG FINE DET 1 SEG WIDE DET 1 SEG FINE DET 2 SEG WIDE DET 2	L1 TLOW XLOW L1 TLOW XHI 1 L1 TLOW XHI 2 .... L1 THIGH

3. Test Vectors

Segment Validation
U segment	Test vector for validated U segment
V segment	Test vector for validated U segment
Tracking Equations
Single hits
PU low t and low xsi	Test vector for low t and low xsi tracking trigger equations in PU spectrometer. Prescale=100 , what means only 1 out of each 100 equations was used to make the vector.
PU low t and high xsi	Test vector for low t and high xsi tracking trigger equations in PU spectrometer. Prescale=100 .
PU high t	Test vector for high t (and all xsi) tracking trigger equations in PU spectrometer. Prescale=1000 .
PI low t and low xsi	Test vector for low t and low xsi tracking trigger equations in PI spectrometer. Prescale=50.
PI low t and high xsi	Test vector for low t and high xsi tracking trigger equations in PI spectrometer. Prescale=50 .
PI high t	Test vector for high t (and all xsi) tracking trigger equations in PI spectrometer. Prescale=2000 .
DI low t and low xsi	Test vector for low t and low xsi tracking trigger equations in DI spectrometer. Prescale=50 .
DI low t and high xsi	Test vector for low t and high xsi tracking trigger equations in DI spectrometer. Prescale=500 .
DI high t	Test vector for high t (and all xsi) tracking trigger equations in DI spectrometer. Prescale=1200 .
DI (wide segments)	Test vector for all-wide-segments tracking trigger equations in DI spectrometer. Prescale=24.
Multiple hits
DI high t double hit	Test vector for double hits  in DI spectrometer: two high t (and all xsi) tracking trigger equations logically added.