test bench for DAQ calibration at the Universit de Genve

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test bench for DAQ calibrationat the Université
de Genève

• leak tests for TPC/readout interface
• what needs to be done to get started
• program for measurements
• test bench
• radioactive sources
• cathode support grid HV protection

M. Di Marco T2K nd280 TPC group meeting UniGe, 3
août 2006
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leak tests setup almost complete !
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leak tests/test bench progress

• DAQ PC installed downstairs, humidiprobe up and
  running
• power supply and voltage reducer/amplification
  for pressure transmitter and PT-100 done !
  (thanks to Pierre and Gaby)
• ADC-22 seems to work (at least for the PT-100)
• new DAQ software by Picotech (received August
  3rd)
• to be installed on DAQ PC in basement
• can be tested with PT-100
• temperature sensors (fortunately, not prioritary)
• very unstable, antenna effect, range too wide
• need to be calibrated but ADC reads 0-2.5V, and
  sensors set to -2.5-2.5V
• best solution find better adapted sensors ?
• pressure transmitter (see later)
• electrostatic field simulations (Tania)
• G10
• waiting for feedback from Gurit (machined piece)
• waiting for feedback from R. Hendersen (mounted
  piece)

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leak tests missing parts
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leak tests pressure transmitter

• P transmitter has a cracking pressure of 200
  mbar needs to be protected ? pressure relief
  valve
• adjusted to 100 mbar at CERN
• connector for P transmitter will arrive August
  21st
• at office 1-1-074 (according to EDH)
• connector for P relief valve doesnt seem to
  exist at EDH
• sent email to person in charge, back August 7th
• machine shop at Université de Genève carry Serto
  and NPT, cryogenics carry Swagelok (no Gyrolok)
• please do not use P transmitter without P relief
  valve
• Florian volunteered to help, back August 10th
• I (Marie) will be away August 6-27th
• follow-up will leave all informations and
  pieces on Florians desk

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leak tests program

• install and test P transmitter
• measure P vs time
• set pressure to 100 mbar, close system
• repeat to make sure it is consistent
• correct for temperature variations (if
  necessary)
• get good fit around 10 mbar
• first perform on Al frame Al module for
  reference
• perform on vetronite (machined, mounted) and
  stesalit
• use Buna-N o-rings monolayer of Mb lubricant
• identify leaks
• with sniffer for coarse check
• borrow He spectrometer for more detailed tests

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test bench design
HV protection 8-10 µm mylar sheet on top of
grid
GEM or mMegas module held verically
fix 2 weak sources in the holes of the grid,
between the cathode and protection mylar count
rate total nb of counts over whole runtime
nb of counts per pad with moving source
stages for automated movement in x and y
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test bench support grid for cathode
1st issue keep the cathode uniform ? small holes
? the grid lines are 1.2mm large (machining
issues) and 5mm thick (for robustness), with 3mm
radius corners (machining issues) 2nd issue
grid lines totally absorb the X-rays ? keep the
middle of the pads free from the shadow, as well
as many of the borders as possible the idea grid
pattern is the same as the padplane pattern, but
shifted
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test bench support grid for cathode
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test bench support grid for cathode
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test bench 55Fe sources
two weaker sources to monitor stability
mMegas
note X-ray tube significantly more expensive and
needs interlock system for radioprotection issues
possible, but do we need it ?
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test bench 55Fe sources

• 1 strong (185 MBq) moving source
• effective activity (given 27.8 BR for Mn-K
  X-rays collimation absorption)
• the stronger the better because of deadtime
  structure
• 2 weak (37 kBq) fix sources
• sources to be ordered at EckertZiegler as soon
  as authorization is obtained from OFS
• discussion over the phone with Divic and Mr.
  Marconato (back from vacation today !)

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test bench 55Fe sources
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test bench collimation of 55Fe source

• the idea insert the source into a metallic tube
  (Cu or st-st)
• mask close to the source window
• 2nd hole at a given distance from the mask
• many options for radius and distance between the
  two collimation holes
• smaller holes ? shorter tube ? less absorption
  in air
• machining/alignment might become difficult for
  tiny holes ?

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test bench collimation of 55Fe source
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test bench weak source for consistency check
the issue should illuminate the padplane
uniformly, without blocking the x,y movements of
the strong source, and not expose the users the
idea stick a pastille source in between the grid
lines
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test bench weak source for consistency
checkand HV protection
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test bench radioprotection issues

• users are not exposed during measurements
• all sources are facing GEM/MM module
• 55Fe considered not very dangerous
• 6 keV X-rays penetrate dead layer of skin
• all sources are sealed
• procedure for mounting/dismounting of module on
  test-bench
• clearly identify the presence of the sources
• metallic window inserted into collimation tube
  instead of garage ?
• aluminum sheet to cover the cathode when removed
  from the gas chamber ?
• stealing
• sources mecanically inserted into setup
• systematically lock the door of the lab in
  basement

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test bench time frame

• mechanical design done ?
• cathode how to apply HV on mylar sheed ?
• gas chamber how to maintain 10 mbar
  overpressure ?
• radioactive sources authorization from OFS to
  be obtained