DØ Run II Cosmic Ray Trigger Signals into L1 Framework (Week of 1/17/2000)
 

	Muon PDT Front End Boards (three Al panels on the front end of the picture) and the corresponding Control Board (one AL panel on the far side of the picture).
	Muon Scintillator Front End crate which is near by the cosmic trigger NIM crate.
	Coincidence of the two end PMT signals is formed to reduce random noise trigger.   This coincidence forms another conicidence with TOP cosmic cap to contrain cosmic ray to the beam line.  This is the low rate (0.05Hz) trigger.The TOP cosmic cap scintillator coincidence to A-f counter signals forms the high rate trigger.
	This NIM crate is at the top of the detector on the West corner.  The left fanout module accepts the signals from the two ends of the beam counter.   The second module forms two separate coincidence trigger signals.
	The two outputs (green cables on the left corner of the picture) from the coincidence module is routed through SE surface of the Toroid to the patch panel under the platform.  The cable bridge can be seen on the right corner of the picture.
	This patch panel was used for Main Ring VETO counters during Run I.   It is located on the NW corner under the platform.
	A close-up view of patch panel. The beam counter installed at its position.  The trigger signals from the detector go to the back of the patch panel.   The two RG158 (green) cables at the bottm right corner carries the low (top) and high (bottom) rate trigger signals to L1 Framework in MCH1.
	The two cables, carrying the low (right) and high (left) rate triggers are input to this NIM 4614 NIM-to-ECL converter before transferred into L1 Framework.
	The signals from the cosmic trriggers need to be timed with the DØ master clock, shown in the bottom crate, in order for L1 framework to issue L1 accept to other crates in accelerator timing.