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DIRC Gas/Water Safety System

The DIRC gas/water safety system provides us with the critically important capability to detect a water leak from the DIRC Stand-off Box (SOB) into the DIRC Bar Boxes by sensing presence of liquid water inside the bar boxes and measuring humidity in the DIRC gas system downstream from the bar boxes. The DIRC safety electronics gathers information from 20 liquid water sensors of our own design, 12 humidity meters, and 2 ultrasonic water-flow detectors, visualizes it, performs a series of logical operations on the sensor data, provides input for computer-controlled read-out electronics (GMBs and SIAMs), and, most importantly, is capable of generating the "Emergency SOB Dump" directive to the compressed air-powered SOB dump valve in case of a water leak from the SOB into one or more bar boxes that may develop as result of an earthquake. Since there is tens of millions of dollars-worth of equipment, most notably CsI crystals in the EMC, that could be damaged should such a leak develop, this safety system was designed to be very reliable, to remain operational for an extended period of time in case of a site-wide power outage, and to provide a manual override feature.

Questions regarding this system should be directed to me, Alexandre (Sasha) Telnov. Should I leave BaBar, contact Richard Kadel and Jaroslav Va'vra. The other people who have experience with specific components of this system include Donald McShurley and Gerard Oxoby (SOB dump valve control box), Steve Dardin and Thomas F. Weber (electronics and power supplies), Thomas B. Weber and Robert Reif (SOB dump valve and plumbing), Paul Stiles (SIAMs), and Georges Vasileiadis (EPICS).

The following documentation is available:

Below is a collection of schematic diagrams, circuit-board layouts, and other files on electronics that I have designed for the DIRC gas/water safety system. All electronics in Rack #38 has been designed with Protel98. The following files are available:

The boards in Rack 5 (on the top of BaBar, not in the Electronics House) were designed using "stone-age" technology: a piece of paper, a red and a blue pens, and a generic CAD program - in this case, the venerable Claris CAD. (Boy, that was so much fun!) I used an HP LaserJet 4MV printer to print PCB layers onto sheets of frosted mylar that were then sent to the Berkeley Lab's Photo Fabrication Shop. Rudy Bartolo of the Berkeley Lab's Engineering Division did a great job fabricating those boards. Although manual PCB layout is a very labor-intensive process, boards made that way look like pieces of fine art compared to boards that have been autorouted with Protel! Here they are:

  • Schematic diagrams, gzipped Postscript: Board #1 (Claris CAD version); Board #1, OrCAD version (color for Xerox C55 and b/w for HPLJ4MV), Board #2 (color for Xerox C55 and b/w for HPLJ4MV), Boards #3 and #4 (color for Xerox C55, b/w for HPLJ4MV, 11"x17" b/w for HPLJ4MV, 22"x34" color for HP DesignJet 650C), Board #5 (color for Xerox C55 and b/w for HPLJ4MV).
  • Schematic diagrams, Adobe Acrobat (PDF) version 3.0: Board #1 (Claris CAD version); Board #1, OrCAD version (color for Xerox C55 and b/w for HPLJ4MV), Board #2 (color for Xerox C55 and b/w for HPLJ4MV), Boards #3 and #4 (color for Xerox C55, b/w for HPLJ4MV, 11"x17" b/w for HPLJ4MV, 22"x34" color for HP DesignJet 650C), Board #5 (color for Xerox C55 and b/w for HPLJ4MV).

Errata: The Claris CAD and OrCAD versions of the Board #1 slightly differ in the way pin numbers are assigned to inverters in the SN7404 chip. The Claris CAD version is the right one, but the OrCAD version contains some extra information, so print them both.

  • Printed Circuit Board composite drawings in color, gzipped Postscript (RED is the top layer, BLUE is the bottom layer, GREEN is the silkscreen, BLACK is the drill pattern): Board #1, Board #2, Board #3, Board #4, Board #5.
  • Printed Circuit Board composite drawings in color, Adobe Acrobat (PDF) version 3.0 (RED is the top layer, BLUE is the bottom layer, GREEN is the silkscreen, BLACK is the drill pattern): Board #1, Board #2, Board #3, Board #4, Board #5.

  • Printed Circuit Board drawings, layer by layer, b/w, actual size, gzipped Postscript (*_Top.* is the top layer, *_Bottom.* is the bottom layer, *_Bottom_rev.* is the bottom layer mirrored, *_Silkscreen.* is the silkscreen layer, and *_Drills.* is the drill pattern): Board #1, Board #2, Board #3, Board #4, Board #5.
  • Printed Circuit Board drawings, layer by layer, b/w, actual size, Adobe Acrobat (PDF) version 3.0 (*_Top.* is the top layer, *_Bottom.* is the bottom layer, *_Bottom_rev.* is the bottom layer mirrored, *_Silkscreen.* is the silkscreen layer, and *_Drills.* is the drill pattern): Board #1, Board #2, Board #3, Board #4, Board #5.

Also available:


Page author(s): Alexandre (Sasha) Telnov
Creation date: APR-28-1999 Last significant update: MAY-17-1999 Expiry date: JAN-01-2010