Minutes of the Tracker technical meeting
May 17, 2000

Ossie talked about a vendor that can supply silicon mechanical samples.  Cut to size from 
150mm wafers and ground to thickness, they would cost $21/sample with 1 week lead 
time.  The slicing spec is +-20 um.  The spec on thickness variation  is 5 um.  Ossie will 
ask for a quote for metalizing the wafer, but he needs a spec for the thickness of 
aluminum.  We decided to make the first ladder fixture to final size and exercise it with 
these wafers.  Ossie noted that we could put fiducial marks on with a laser.  Hartmut will 
ask Sergei at UCSC to look into making a single mask and etching aluminum at CIS.

John said that the drawing of ladder jig is nearly completed.  It will need to be modified 
for new size, but he does strongly favor going immediately to the final size.

Harmut related the outcome of the committee on detector size and pitch.  8.95 cm square 
detectors were recommended, with a pitch of 228 um.  The strip width is TBD.  From the 
field calculations done at Trieste, going from a pitch of 208 um to 235 um, the field at the 
corner of the implant increases by 10%, keeping width constant.  The simulations clearly 
show how the overhang of aluminum keeps the fields down at the implant corner.  This 
all agrees well with Ohsugi’s results.  Hartmut noted that we want to keep the active area 
square for the square detectors.  Details of the specifications and layout are being worked 
out.

Hartmut asked if Guido would like some existing detectors 9.5 cm by 9.5 cm.  He 
remarked that Agile is a different pitch.

Guido said that Michela  has returned from CERN.  She found that the group there is 
collaborative and they believe that a C, Pb composite would work but is a significant 
complication.  They also suggest using a compliant layer.

Eric has done some analysis of using a compliant layer between lead and kapton.  Simple 
calculations indicate that the stress levels in Si are not significantly improved or maybe 
are worse.  He assumed 8 um equivalent of copper and 110 um of kapton.  He suggests 
using a thin carbon layer between the compliant adhesive and the kapton.

Guido remarked that Agile will use 7% X0 tungsten converters.  

The spec on temp change rate is less than 5C per hour.

UCSC is planning to purchase a thermal control chamber for about $6K, primarily for 
testing of electronics.  

UCSC is also looking into stages and glue dispensers for development of a ladder potting 
procedure with much better automation than what was used in the BTEM.  Bill found a 
stage with 3um resolution and 8in travel and 76mm/s top speed.  It would be controlled 
by Labview.  We also probably need a volumetric control glue dispenser.  Martin 
recommended pricing an integrated system including dispenser and stages.

Masa presented a report on testing of the HP 0.5um test chip.  The detailed report is on 
the tracker web site.  The noise and gains are good.  He also studied the response to large 
signals.  Saturation of the TOT is at about 90us.  The rate is about 3us per mip.  The noise 
agrees well with occupancy results from the beamtest data.  Hartmut would like to see the 
discriminator delay and the TOT as function of overdrive.  

Decisions:
1. Make the first ladder gluing prototype to the final detector size.

Action Items:
1. Ossie: get quotations for metalizing wafers and for marking with a laser.
2. Hartmut: talk to Sergei about costs and time for making a metal mask at CIS.
3. Hytec will do some analysis of a converter/face-sheet/detector structure using 
compliant layers and will come up with suggested configurations to test. 
4. Masa: measure the delay and TOT of the HP 0.5um discriminator as a function of 
signal overdrive.
5. Bill and Gwelen: price integrated glue dispensing systems.