INTERCOMPARISON OF CRYOGENIC RADIOMETERS USING SILICON TRAP DETECTORS

An intercomparison of cryogenic radiometers of HUT/VTT (Finland), PTB (Germany) and SP (Sweden) using silicon trap detectors was performed. Also results of monitoring of the responsivities of trap detectors ove r a 6 year period are presented. It was noticed that several non-ideal ities can undermine the agreement between results of calibrations. The non-uniformity of the responsivity of trap detectors made the results sensitive to alignment and beam size, The nonlinearity of some trap d etectors was found to be large. The average relative differences in th e results of the laboratories, when all known corrections are applied, are +1 x 10(-4) for HUT-PTB, -3.7 x 10(-4) for SP-PTB and -4.3 x 10(- 4) for SP-HUT,with standard uncertainties of 4.3 x 10(-4), 3.0 x 10(-4 ) and 4.4 x 10(-4), respectively.