Experience with the MVD Living around the beam pipe Components, connections, signals, systems Hubert...
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Transcript of Experience with the MVD Living around the beam pipe Components, connections, signals, systems Hubert...
Experience with the MVD
Living around the beam pipe
Components, connections, signals, systems
Hubert van Hecke - Los Alamos
Living around the beam pipe
• Every year we had to clear the beam pipe
The central magnet is moved every yearThe beam pipe was not where it was supposed to beThe beam pipe is supported in the CM iron/nosecone
Beam pipe
Official supports
Non-official supports
Nosecone
MVD support plate
Understand environment
Provide for easy movement of the NCC halves
or
Ensure that the NCC clears the beam pipe for all positions of the CM
Flanges, supports, bigger diameter
or
Have the supports mounted to the NCC itself
silicon strips and pads
Silicon strips5x8 and 5x5 cm256 strips200 um pitch
Silicon pads252 pads (12 cols, 21 rows) 2x2 - 6x6 mm double metal
traces lay over pads simplify connectionsIncur few % crosstalk
silicon to kapton cable
Dry adhesive was used to bond Silicon to KaptonWire bonds were encapsulated in black potting material(clear potting cured but stayed more sticky)cannot inspect bonds visually
kapton cables
6, 8, 14, 19 cm long
0.05mm KaptonTraces: 0.005mm Cu (x .5 area)Ground: 0.005mm Cu (x .1 area)
Kapton cables
The extreme thinness and the (almost) absence of shielding ground planes was driven by the requirement to keep the mass facing the central arms low.
MCM
19 chips: 8 32-channel preamp / discriminators, 8 32-channel AMU / ADC, 2 Xilinx, 1 opamp in a 5x5cm package. Produces a digital data packet.
MCM
Low yield, but the ones that worked never failedDiscriminator never workedXilinx programming proved a vulnerability
Need more time for ASIC development have Xilinx programmer in-house
output cable
50 traces, 0.5mm pitch, controlled thickness and width
Analog, digital, reference voltages, 10, 40 MHz clocks, serial controls, data out.
Output cable
MCM to power/comm board
Power/comm board
ZIF connectors, Elco 0.5mm pitch. Rated for 50 open/close, good for much more
Vertical spacing to << 0.5mmLimited space, so made custom toolsfor opening/closing ZIF connectors
160-pin JAE
power/comm to motherboard
Board spacing 9mm
Fixture to hold and push up to 6 160-pin connectors
Trace density in vicinity of the 160-pin connectors forced the motherboard to be 14-layer
motherboard to cablesThe diameter of the MVD enclosure (60 cm) was determined by the area taken up by the cable connectors, not by the actual Si detectors.
Keeping moist air out is necessary if you run the detector below the dew point. Some connectors were very leaky, and required insulating foam barriers.
Signal cables were .05” pitch solid-core ribbons, vulnerable to bending failure. Strain relief clips were iron and not used because of the mag. field
Cables are flexible, bundles are not (recall the yearly uninstall / reinstall) Connectors were on a surface that was not accessible after installation.
Need ALL components designed before starting mechanical design
downstream electronics
Downstream electronics was badly designed and unsupported by the designers.
AIM - Arcnet Interface module: arcnet fiber to copperTCIM - Timing and Control Interface Module: mode bits fiber to copperDCIM - Data Collection Interface Module: data demultiplexing, multiplexing module, copper to fiber
Needed more development time
Need system tests, not just single boards
Need designers to remain on the team (long enough)
Xilinx programmers on the team