Large Wire Chambers

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Large Wire Chambers
Petros Rapidis, Fermilab

• Or To boldly go where nobody has gone before
• Frame chambers (say up to 5x5 meters) usually
  made on winding machines
• Cylindrical chambers (ala CDF say) done by
  stinging in situ, but situ here is usually a
  clean lab followed by a truck ride to the expt
  location
• Some other large chambers made by individual wire
  stringing.
• Large liquid argon wire chambers not
  calorimeters- we have only one example, ICARUS.
  In addition the quasi-example of LANDD

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The ICARUS experience
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A floating construction to avoid distortions
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Note the scale vs the atrium of the high
rise! Also note the ice-cream parlor quality of
this operation !

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LANDD not of much help a frame chamber probably
built ahead of time
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WHY?
For transparency E n11.5?E n
With E drift 0.5 kV/cm, 7 wire planes -  2
grid planes 1 screen plane made by vertical
wires referred to ground -  2 induction
planes with horizontal wires biased at 337.5
V -  2 collection planes with vertical wires
biased at 675 V
Stainless steel wires with ?100 ?m at a 3 mm
pitch. Channel maximum capacitance in LAr 23
pF/m ? 40 m 2 m Cable ? 1 nF ENC ? 1600 e- RMS,
S/N ? 8-10 for minimum signals
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WIRE MATERIAL AISI 302 Stainless Steel,
4/4 hard drawn, polished Max. Load Rm 2350
Nmm-2 Elastic Limit Rp0.2 2100 Nmm-2
For 150 micron wire 30 m long 27 mm elongation
due to tension at 2.1 kgf 9 mm due to
temperature excursion
sag ? L2, cos (?)
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Use sketch here
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Stability of grid plane

• ?8.854 e-12 F/m
• CF/m14 pF/m 14 e-12 F/m
• L 30m
• S5mm5 e-3 m
• V500Volts
• T in newtons
• But 500 may be too large, ? is larger for
  argon,
• L is more
  like 5 meters so it is OK

Are microphonics an issue here ?
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Lots of room for weights and pulleys
Also a similar structure buried in the side
pillars
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A Frame approach
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A top truss and side walls we need more
information from CBI also about doors, cranes,
holes, discarded BLT sandwiches

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How large chambers can you string???
String(ing) Sextet L. Bartoszek, B. Fleming, H.
Jostlein (in absentia), K.Kephart, A. Para, P.
Rapidis
5 wires, 25 m long, 4 mm spacing
WH 15 floor
WH 6 floor
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But enjoyable as this was this is not the way to
go Techniques have to be developed e.g. a
wire stringing machine(s) ? All of this in an
environment of cleanliness And one has to also
think about auxiliary instrumentation (thermometer
s, motion transducers, stirrers,
bubblers,) And Also auxiliary systems (e.g. a
survey system inside the tank). Do we need a long
prototype 30m long ?
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10 cylindrical (astigmatic) distortion
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Rule of thumb local distortions up to say 5 of
pitch are probably acceptable, and global
distortions that do not violate the above rule
(but are uniform) are also acceptable
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The End