Radioactive%20source%20test%20in%20Ferrara%20M.%20Andreotti%20

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Radioactive source test in FerraraM. Andreotti
G. CibinettoSeptember 11 2003

• Source type Cs137
• Scan Test on 3 profile _at_ 5700 V with
• Zeus gas mixture moving the source with a toy
  car. Speed about 1-2 cm/s.
• Same tests have been done with different gas
  mixture (8/16/76 Isob/Ar/CO2) at lower voltage
• same results.

2
Movements of source
3
Results from scan test

• Scanning all 3 profiles we didnt find spike in
  current.
• Values of currents with source are about uniform
  varing between 300-700 nA.
• We tried to scan with and without grounding
  shield above the tube no differences have been
  found
• After some attempts we had chance to do scan test
  on two cells (1 and 2) of one bad profile (slide
  5).

4
Scan test on one cell
5
Brief history of one bad profile

• Plateau was ok.
• After some time _at_ 5700 V the tube starts to
  discharge, then also at 5600 V (with and without
  source).
• Scan test _at_ 5400 V no strange behavior, but a
  scan test at this value doesnt make much sense.
• After 2 hours of voltage off we are able to scan
  two cells _at_ 5700 V, no spike appears.
• Without source _at_ 5800 V it starts to draw 2.5 muA
  and to turn off the dicharge we had to lower the
  voltage _at_ 4500 V.
• This profile cannot pass long term test.