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54.1 FRONT PANEL . . . . . . . . . . . . . . . . . . 54-1
54.2 UPPER BACKPLANE . . . . . . . . . . . . . . . . 54-1
54.3 FUNCTIONAL DESCRIPTION . . . . . . . . . . . . . 54-2
54.4 OPERATIONAL DESCRIPTION . . . . . . . . . . . . 54-2
54.5 CAMAC COMMAND SUMMARY . . . . . . . . . . . . . 54-2
54.6 POWER SUPPLY REQUIREMENTS . . . . . . . . . . . 54-4
54.7 DRAWING PACKAGE NUMBER . . . . . . . . . . . . . 54-4
54.8 RESPONSIBLE ENGINEER . . . . . . . . . . . . . . 54-4 CHAPTER 54 TRIGGER GATE AND SYNCHRONIZER (TGAS)
54.1 FRONT PANEL o Double Width CAMAC Module o Two Isolated BNC conectors, to receive the externaly phase-shifted 178.5 MHz IN, used to synchronize each channel o Two LEMO connectors, to receive the NIM level EXT TRIG (External Trigger) input for each channel o Two LEMO connectors, sending the double-NIM, gated and synchronized CH OUT (Channel Output) output for each channel o Two LEMO connectors, sending the double-NIM, gated CH MONITOR (Channel Monitor) output for each channel o One Isolated BNC connector to receive the 50 USEC PERMISSIVE input o One Isolated BNC connector to receive the TIU PERMISSIVE input o Eight LEMO connectors, providing four NIM GATE inputs per channel o Two PP VIEW displays, indicating for each channel which PP beam code the CH MONITOR output is monitoring
54.2 UPPER BACKPLANE o CH1 is received from the upper backplane connector pins P2-5 and P2-6 o CH2 is received from the upper backplane connector pins P2-7 and P2-8
TRIGGER GATE AND SYNCHRONIZER (TGAS) Page 54-2 o 119 MHz is received from the upper backplane connector pins P2-19 and P2-2054.3 FUNCTIONAL DESCRIPTION The TGAS provides two independent channels of timing signals that are gated by a variety of sources, including the 50 usec permissive and the TIU permissive, and synchronizes each of these gated timing signals with externally phase-shifted 178.5 MHz waveforms. In effect, this module consolidates several of the beam gating functions required at the SLC injector, and provides an extremely high resolution vernier delay by synchronizing the gated trigger signals with externally phase shifted 178.5 MHz signals. Monitoring of the gating signals is provided through the CAMAC interface.
54.4 OPERATIONAL DESCRIPTION Trigger signals to be gated and synchronized may be received from either the SLC auxiliary upper backplane (PDUII channels 1 and 2), or from external sources received as NIM signals through front panel LEMO connectors (CH1 EXT TRIG and CH2 EXT TRIG). The selection of the input source is not provided for; outputs are the logical sum of the trigger input sources. Outputs are gated by the 50 usec permissive, the TIU permissive, and 4 external NIM GATE signals received by front panel LEMO connectors. Any of these permissives may be bypassed by removing jumpers on the TGAS printed circuit board. The gated trigger signals are synchronized with externally phase-shifted 178.5 MHz signals. Because the trigger signals are typically derived from the PDUII, which has a fundamental granularity of 8.4 nsec, and synchronization with a 178.5 MHz waveform has a 5.6 nsec ambiguity, the triggers are first resynchronized with a selected edge of the PDUII 119 MHz clock before synchronizing them with the 178.5 MHz source. This allows the shifting of signals by 4.2 nsec, which is sufficent to allow any desired delay by varying PDUII delays, 119 MHz edges, and 178.5 MHz phases. In principle, all delays are possible with externally phase shifted signals up to 238 MHz. Latches in the module store the state of the permissives when a trigger is received on a selected beam (PP) code. This data is stored until it is read out by CAMAC. Following the read, the latches are reset.
54.5 CAMAC COMMAND SUMMARY o F(0)A(0) R8-R1 reads out the following information for Channel 1. R6-R1 contain the state of the permissives when the trigger pulse on the requested beam (PP) was received. R1 - 50 usec permissive was present (or bypassed)
TRIGGER GATE AND SYNCHRONIZER (TGAS) Page 54-3 R2 - TIU permissive was present (or bypassed) R3 - CH 1 NIM GATE 1 was present (or bypassed) R4 - CH 1 NIM GATE 2 was present (or bypassed) R5 - CH 1 NIM GATE 3 was present (or bypassed) R6 - CH 1 NIM GATE 4 was present (or bypassed) R7 - Fiducial detected for the requested beam (PP) R8 - 119 MHz clock edge used to resynchronize CH 1 Trig X = Q = 1 is returned. The data in the gate status latches (R7-R1) is reset following the CAMAC read. o F(0)A(1) R8-R1 reads out the following information for Channel 2. R6-R1 contain the state of the permissives when the trigger pulse on the requested beam (PP) was received. R1 - 50 usec permissive was present (or bypassed) R2 - TIU permissive was present (or bypassed) R3 - CH 2 NIM GATE 1 was present (or bypassed) R4 - CH 2 NIM GATE 2 was present (or bypassed) R5 - CH 2 NIM GATE 3 was present (or bypassed) R6 - CH 2 NIM GATE 4 was present (or bypassed) R7 - Fiducial detected for the requested beam (PP) R8 - 119 MHz clock edge used to resynchronize CH 2 Trig X = Q = 1 is returned. The data in the gate status latches (R7-R1) is reset following the CAMAC read. o F(16)A(0) W1 selects the phase of the 119 MHz clock used to synchronize the Channel 1 trigger. W1 = 1 selects the rising edge of the 119 MHz clock, W1 = 0 selects the falling edge. X = Q = 1 is returned. o F(16)A(1) W1 selects the phase of the 119 MHz clock used to synchronize the Channel 2 trigger. W1 = 1 selects the rising edge of the 119 MHz clock, W1 = 0 selects the falling edge. X = Q = 1 is returned. o F(17)A(0) W8-W1 selects which beam code shall enable the CH 1 MONITOR output and the Channel 1 gate status latches. This value is displayed on the front panel as CH 1 PP VIEW. X = Q = 1 is returned. o F(17)A(1) W8-W1 selects which beam code shall enable the CH 2 MONITOR output and the Channel 2 gate status latches. This value is displayed on the front panel as CH 2 PP VIEW. X = Q = 1 is returned. o F(19)A(8) W16-W9 receives the broadcast pattern PP beam code. o F(27)A(0) X = 1. Q = 1 if a fiducial on the requested beam code has been detected, indicating valid data is in the Channel 1 gate status latches if a CH 1 TRIG was received. o F(27)A(1) X = 1. Q = 1 if a fiducial on the requested beam code has been detected, indicating valid data is in the Channel 2 gate status latches if a CH 2 TRIG was received.
TRIGGER GATE AND SYNCHRONIZER (TGAS) Page 54-454.6 POWER SUPPLY REQUIREMENTS +6V @ 2.0A -6V @ 3.0A
54.7 DRAWING PACKAGE NUMBER 233-122
54.8 RESPONSIBLE ENGINEER E. Linstadt