Abstract. In 1994 the Consultative Committee for Photometry and Radiometry (CCPR) decided to start an international comparison of cryogenic radiometers. The BIPM acted as pilot laboratory. Following the publication of the results of this comparison in 2000, the Istituto Elettrotecnico Nazionale (IEN, Italy) expressed the wish to repeat the comparison. The report describes the results of this subsequent bilateral comparison between the BIPM and the IEN.

The comparison was carried out by using silicon trap detectors as transfer instruments, to be calibrated at a number of laser wavelengths at the IEN and the BIPM.

The results obtained by the IEN in the subsequent comparison are in much better agreement with the BIPM results than in the previous comparison. The BIPM providing a link to the previous large-scale comparison, this leads also to a considerably better agreement between the IEN and the other participants of the first comparison.

Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by CCPR, according to the provisions of the Mutual Recognition Arrangement (MRA).