出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：National metrology institutes (NMI) keep the national primary standards for all SI units and for
some derived quantities required for the measurement of ionising radiation. In case of neutron
measurements, the basic quantities are the total emission rate of sources and the (spectral)
fluence rate.
Only a few NMI’s or their associated laboratories are world-wide engaged in neutron
measurements and regularly compare their primary standards in key comparisons organised by
CCRI(III), the section III of the consultative committee for ionising radiation CCRI of CIPM
(international committee for weights and measures). However, calibration measurements are
accepted in some countries only if the measurement is traceable to their national primary
standard even if the underlying procedure is supported by international comparisons.
In order to overcome these restrictions, the leading NMI’s recently signed a Mutual Recognition
Arrangement (MRA) which states that the calibrations of those laboratories for which the
applied calibration measurement capability has been internationally approved will be accepted
world-wide. Regional metrology organisations (RMO), in co-operation with the international
bureau for weights and measures (BIPM), jointly organise the approval of submitted CMC’s to
confirm compliance with the agreed service categories and rules for specifying the CMC’s.
Provided these specifications are supported by successful participation in comparison exercises,
the CMC’s and the associated degree of equivalence are published in the key comparison data
base (KCDB, parts B and C) on the BIPM webpage. Calibrations performed according to
approved CMC’s are then accepted world-wide.
