Trigger logic for PMD
After the RHIC collision, it is expected that we will get Pretrigger after
500 ns and also we will get the L0 ( Level zero trigger; ref: star trigger web
page) after 1.1 micro-sec.
Now as per our Electronics requirement we have implemented the following :
i) as soon as we get the Pretrigget we send the BUSY signal and after 814 ns
( after the RHIC collision) we send the T/H to the FEE as it is required.
ii) Now there are two conditions :
(a) No L0 has not arrived within the Pre-defined time
(b) L0 arrived within its Pre-define time.
(a) If L0 does not arrive, Clear the T/H and BUSY. BUSY has to be cleared after
4.5 micro Sec, from it starts , since the base recocery time of FEE is 4.5
(b) If L0 arrives,
-send T/H and BUSY.
-Check, for this L0, does Pretrigger exists. If YES case (aa) and if NO case
(aa) Send Trigger to Sequencer adn in turn Sequencer will Generate the
Clocks, T/H, CLR, BUSY, and CONV. The Clocks has to be FAN IN/OUT and send to
several chains to FEE.
Similarly for T/H ( Two T/H s are OR'ed ; see implementaion), CLR. The CONV has
to pass through the Delay module and feed to CRAMS. CRAMS will convert the data
and sends the Ready to Sequencer and Readout starts. After the readout FEE clear
sends and also the Software BUSY ( VME_BUSY) is withdrawn.
(bb) Do not Gernerate the Trigger and like case (a).
The timing diagram of this logic is shown in
PMD trigger timing.
PMD trigger scheme. gives the exact implementation
of the above Logic.
Besides this it has the following options :
If no L0 and Pretrigger is there the TTL signal can be generated from VME
and converted to NIM and fed to the logic and will automatically generate
Pretrigger and L0 ( Simulated) and give the trigger to sequencer and will
generate the associated CONTROL signals for FEE.
Connect the Jumper for "Jump to test" and give the input to Pretrigger
( NIM pulse of 100ns width @1KHz or so from pulser ) and rest of the things will be
The Numbering Convention used in the Diagram :
say , 5-7; It is the module in Slot 5 of NIM Crate and the 7th Gate of that
module starting from the TOP.
The List of modules in different Slots are give in the Diagram.
Download Power-point file for PMD-STAR-DAQ