Activation measurements in support of the 14 MeV neutron calibration of JET neutron monitors

Highlights: • Characterization of 14 MeV neutron generator was described. • Threshold nuclear reactions have been applied to monitoring the 14 MeV neutrons. • Neutron activation method allowed for determining neutron emission rate. • Description of second phase of 14 MeV neutron monitors calibration of JET tokamak. - Abstract: In preparation for the upcoming deuterium-tritium campaign at the JET tokamak, the ex-vessel fission chamber neutron diagnostics and the neutron activation system will be calibrated in absolute terms at 14 MeV neutron energy, to a required accuracy of less than 10%. Two nominally identical DT neutron generators were chosen as the calibration sources, both of which were fully calibrated and characterized at the UK's National Physical Laboratory. The neutron activation method was adopted as a complementary method for the purpose of determining the absolute value of the neutron yield from the neutron generators and to provide a means of cross check for the active detection methods being employed. The work being presented here shows the derivation of the neutron emission rate from the neutron generators based upon experimental activation foil measurements.