Preparation of samples, operation of counting systems, and calculation of results remain as described previously (Harkness and Wilson, 1973).

The following list of dates is of archaeologic samples submitted in 1971–2, using the counting equipment described in R, 1971, v 13, p 468. Ages are quoted with a 1σ counting error which includes statistical variation of the sample, background, and standard count. The reference year is ad 1950 and 0.95% NBS oxalic acid for 14C dating is the standard. The half-life used is 5570 years.

The following list includes samples dated in 1973. Benzene is used as the carrier of natural 14C activity as previously described (Punning et al, 1973). We used both 1-channel and 2-channel scintillation devices. The detector shield comprises 10cm lead. Around the detector we put 16 Geiger-Mueller type counters in anticoincidence circuit with output signals from detector. It decreased the average background ca 20 to 40%.

In September 1970, the laboratory moved into new premises on the ground floor of a new building. The measuring room is constructed of low radioactive limestone concrete and is lined with grounded copper plate. Air conditioning insures a working temperature of 20 ± 1°C and a relative humidity of 40%.

A radiocarbon facility has been installed at the University of California, Riverside (UCR) to support interdisciplinary studies including archaeologic, archaeometric, geophysical, and geologic research. The laboratory was built between 1970 and 1973. Initially, a sample pretreatment and combustion system designed for a proportional CO2 counting system was installed. It was designed after concepts developed at the University of California Los Angeles (UCLA) and New Zealand (Institute of Nuclear Sciences) Laboratories, and began processing samples in November 1972.

The dating equipment and operating conditions remain essentially as previously described. All samples are from Ireland unless specified.

Measurements have continued with the same proportional counter system, pretreatment procedure, methane preparation and measurement, and calculation using a half-life of 5568 ± 30 years, as described previously (R, 1970, v 12, p 298–318). Uncertainties quoted are single standard deviations originating from standard, sample, background counting rates and half-life. No 13C/12C ratios were measured.

The radiocarbon dating facility is part of the UM Geochronology laboratory housed in the Department of Geology, University of Miami, Main Campus. The laboratory was established to carry out and support research in Pleistocene marine geology, particularly in the Caribbean, and to act as a specialized teaching facility of geochronologic research using radiometric age dating techniques.