Mechanics

1
Status report on DC

• Mechanics
• Foil
• Frame and Print
• Anode
• Inner cathode
• Hood
• Pressure control He bag target
• Electronic
• Schedule

2

• Mechanics

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2. Foil
Order a) first foil to check, 250 nm b) send 59
others up to now 3 iterations of a) Geometry OK
.1 vertically, -.1 horizontally Third
foil ? larger width of the non aluminized
separations between the strips smaller size of
the aluminized reference crosses It looks like
if the etching was done in 2 sequences with a
shift perpendicular to the strip by roughly a
fifth of the separation.
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Resistivity

• interruptions, too thin
• Ok ! Too thin
• Many problems,Thicker

  the resistance of foil bands (30 cm long and
2 cm wide) before etching Ohmcm
after etching Ohmcm foil2 2 .0
1.9 foil 3 1.5 gt 18.0 standard
aluminized Mylar foil 1.1 2 concentric
electrodes (r 1mm and 17 mm). foil2
1.1 to 1.6 1.1 to 1.6 foil 3 .74 to
2.2 3.3 to 20 standard aluminized Mylar
foil .71
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transparency
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3. Frame and Print A) Anode

• First simultaneous use of carbon frame and
  print-gt successful check of information from the
  telegraph equation and units simulation (see
  later)
• Experience about details of the procedure to
  built and equip anode frames
• First iteration simulation of how the frame
  should be ordered to realize with mechanical
  tension what we finally want to have ? second
  order
• Built in a always working Al prototype with
  cathode foil
• 5. Wires problem of other PSI groups solved

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3. Frame and Print B) Inner cathode
Stretched carbon fibers(1000x d6mm) and
deformed ROHACELL
Carbon brings a factor 5-7
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• Same iteration as anode
• Good to 10-15
• linear matching with tension on carbon fiber
  wire
• lt 200 g/cm but as much as possible

Procedure under control Actually at PSI last
production turn to document precisely the size of
deformations ? PRODUCTION
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3. Frame and Print C) Hood
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DC report june_04,J.E.
Mounting of Hood foil

• To do better Stretch vertically and fix the
  width
• Modify the shape of the hood to have a larger
  flat surface to glue
• Machine a foam structure in ROHACELL 30
• Adapt the cathode foil procedureOnly minor
  modifications to the previously designed tools

Largest height Not disturbing the cell
Long design time Long delivery time
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On the carbone fiber and foam structure
On the foil
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bubbler
F0
pb
p
Pa
Fo
Fi
Fo a (p-pa) V V0 c (p-pb) Fi -
Fo d(kVp)/dt k (dp/dt) (V0 c (p-pb)
cp) dp/dt (Fi a (p-pa) )/cp a 3
cc/(minmbar) c 588 cc/mbar dp/dt
.2 mm / 10 mbar
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/2
/20
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4. He bag Pressure control
young positrons traverse 1 Foil Leaves space
for TC Cable duct is tight More complicated than
overall bag
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Hermes, Belle (Openshaw,TRIUMF) MKS Too
expensive, big size, magnetic
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He bag
He C2H6
WC
15x
WC
He
v
1.3 g/mbar on the chamber 1.7, 8.6,13.6
mbar for 10 cm of He He-ethane,Air ? evt. 2 or
3 groups of chambers 30 mbar for 1m tube(
radius 2mm,1 cm3/s of Air), 23 mbar for
He(50),C2h6(50) Gas input in the chamber 15
cm of tube with half diameter Total gas impedance
should not vary more than 20 to have healthy gas
flow in all chambers
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Electronic

• uncertainty on why no charge division effect seen
  on small prototype
• -gt bad matching of anode impedance on print
  impedance (correction out of range for print)
• Program with telegraph equation and print unit
  simulation
• Decoupling capacitor not optimized
• Practically preamps survives HV breakdown of 2.1
  KV 3 pF
• Tool ready to be used
• Cables and preamps production sufficient to test
  correctly the Al prototype with anodes

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2.82 nF
.82 nF
Influence of decoupling capacitor
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Coming

• Test next foils .
• Test on old hood to check principle and tools
  scale of foil deformation on pressure ?order
  Carbon Hood_0 (7 weeks)
• Last turn Detailed measurement of elasticity
  and deformations of inner cathode, final order (
  5 weeks)
• Sr-source run with DRS (not luxurious, 28 for 36
  needed) of the Al-prototype (C-anode frame
  cathode foil 2)
• -gt confirm results of small DC for the 11
  prototype
• -gt ev. Get a measured limit on the necessary
  cathode resistivity
• 2 Russians (01/03/05 for 6 months)

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Drift Chamber
2002
2003
2004
2005
Full Prototype Beam test
Medium Prototype
Charge division Cosmics
Full Prototype
Full Detector (18 DC)
Medium Prototype
Charge division Cosmics
COBRA
inside
outside
Full Size Prototype
Inside COBRA
Full Prototype
Full Detector (18 DC)
Test
Milestone
Assembly
Design
Manufacturing
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Drift Chamber
2002
2003
2004
2005
Full Prototype Beam test
Medium Prototype
Charge division Cosmics
Full Prototype
Full Detector (18 DC)
Medium Prototype
Charge division Cosmics
COBRA
Full Size Prototype
inside
outside
Full Prototype
Full Detector (18 DC)
Inside COBRA
Test
Milestone
Assembly
Design
Manufacturing
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