The purpose of this monograph, number 5 in the series, is to present the recommended values of nuclear and decay data for a wide range of radionuclides. Activity measurements for more than fifty-five of these radionuclides have already been the subject of comparisons under the auspices of Section II (dedicated to the Measurement of radionuclides) of the CCRI. The material for this monograph is now covered in four volumes. The first two volumes contain the primary recommended data relating to half-lives, decay modes, x-rays, gamma-rays, electron emissions; alpha- and beta-particle transitions and emissions, and their uncertainties for a set of sixty-eight radionuclides: Volume 1 for those radionuclides with mass number up to and including 150, and Volume 2 for those radionuclides with mass number over 150. Volume 3 contains the equivalent data for twenty-six additional radionuclides as listed, and re-evaluations for ¹²⁵Sb and ¹⁵³Sm; Volume 4 contains the data for a further thirty-one radionuclides with re-evaluation for ²²⁶Ra while the present Volume 5 includes 17 new radionuclide evaluations and 8 re-evaluations of previous data as identified in the contents page. The data have been collated and evaluated by an international working group (Decay Data Evaluation Project) led by the LNE-LNHB. The evaluators have agreed on the methodologies to be used and the CD-ROM included with this monograph contains the evaluators' comments for each radionuclide in addition to the data tables included in the monograph.

The work involved in evaluating nuclear data is ongoing and the recommended values are updated on the LNE-LNHB website at http://www.nucleide.org/DDEP_WG/DDEPdata.htm.

The BIPM and the DDEP are most grateful to the International Atomic Energy Agency (IAEA) for their assistance and financial support to some evaluators in the production of data for Volumes 1 to 3 through their Coordinated Research Project "Update of x-ray and gamma ray decay data standards for detector calibration and other applications" and for Volumes 4 and 5 through their Coordinated Research Project "Updated decay data library for actinides". The BIPM and the DDEP are indebted also to some other evaluators who participate in the United States Nuclear Data Program (USNDP) for their support to these publications.

The publication of further volumes of Monographie 5 is envisaged when necessary to add new radionuclide data or re-evaluations in this more permanent format that can be referenced easily.

Although other data sets may still be used when evaluating radionuclide activity, use of this common, recommended data set should help to reduce the uncertainties in activity evaluations and lead to more coherent results for comparisons.