backThe instruments used for the measurement of the neutron fluence often contain components whose long-term stability is decisive for the measurement uncertainty. The most important means for the quality assurance of neutron measurements in the national metrology institutes (NMIs) are, therefore, the key comparisons which are organized every ten years by the Advisory Committee for Neutron Measurements of the Meter Convention with the support of the BIPM.
In these comparisons, the participating institutes must carry out "blind" measurements of the fluence calibration factor of an unknown neutron detector at the same accelerator facility. The results are evaluated by the coordinating metrology institute, stored in a database of the BIPM and published. They form the basis of the measurement and calibration capabilities which the NMIs offer in neutron metrology.
The intercomparison measurement of the fluence of mono-energetic neutrons which is currently still valid was carried out at the AMANDE accelerator facility of the French institute IRSN in 2012. The figure shows the results obtained.
Results of the comparison measurement of the fluence of mono-energetic neutrons with energies of 24 keV, 565 keV, 2.5 MeV and 17 MeV carried out at the accelerator facility AMANDE of the French institute IRSN in 2012. The quantity to be measured is the fluence calibration factor of an unknown neutron detector. The Key Comparison Reference Value (KCRV) is the mean value of the results of all participants.
Literature
- V. Gressier et al.:
International Key Comparison of Neutron Fluence Measurements in Monoenergetic Neutron Fields ‑ CCRI(III)-K11
Metrologia 51 (2014), Technical Supplement, 06009,
available online at www.bipm.org/utils/common/pdf/final_reports/RI/CCRI(III)/CCRI(III)-K11.pdf