The main spectrometer is one of the major components of the KATRIN EXPERIMENT (70 meter total length).
In this spectrometer the energy of the electrons resulting from tritium decay will be measured with a previously unattainable accuracy.
To carry out this measurement requires an ultrahigh vacuum in the spectrometer vessel.
The vacuum vessels dimensions are: diameter = 10 m, length = 24 m, volume = 1300 m3, inner surface = 700 m2, mass = 200 tons.
The vacuum requirements:
- operating pressure < 10-11 mbar
- wall outgasing rate < 10-12 mbar l/s cm2
- acceptable helium leak rate for each flange and individual leak test < 10-10 mbar l/s
A very detailed and methodical helium leak testing program for all entical welding seams and flanges has been implemented.
A preliminary acceptance test at the vacuum vessel manufacturing plant has shown that all requirements of the specification were fulfilled.
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