Use of the small gas proportional counters for the carbon-14 measurement of very small samples

Conference · Thu Jan 01 04:00:00 EST 1981

OSTI ID:5319801

Sayre, E V; Harbottle, G; Stoenner, R W; Otlet, R L; Evans, G V

Two recent developments are: the first is the mass-spectrometric separation of /sup 14/C and /sup 12/C ions, followed by counting of the /sup 14/C, while the second is the extension of conventional proportional counter operation, using CO/sub 2/ as counting gas, to very small counters and samples. Although the second method is slow (months of counting time are required for 10 mg of carbon) it does not require operator intervention and many samples may be counted simultaneously. Also, it costs only a fraction of the capital expense of an accelerator installation. The development, construction and operation of suitable small counters are described, and results of three actual dating studies involving milligram scale carbon samples will be given. None of these could have been carried out if conventional, gram-sized samples had been needed. New installations, based on the use of these counters, are under construction or in the planning stages. These are located at Brookhaven Laboratory, the National Bureau of Standards (USA) and Harwell (UK). The Harwell installation, which is in advanced stages of construction, will be described in outline. The main significance of the small-counter method is, that although it will not suffice to measure the smallest (much less than 10 mg) or oldest samples, it will permit existing radiocarbon laboratories to extend their capability considerably, in the direction of smaller samples, at modest expense.

• Research Organization: Brookhaven National Lab., Upton, NY (USA); UKAEA Atomic Energy Research Establishment, Harwell. Low Level Measurements Lab.
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 5319801
• Report Number(s): BNL-30277; CONF-810409-4; ON: DE82004804
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400103* -- Radiometric & Radiochemical Procedures-- (-1987)
58 GEOSCIENCES
580100 -- Geology & Hydrology-- (-1989)
AGE ESTIMATION
ARCHAEOLOGICAL SPECIMENS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBON 14
CARBON ISOTOPES
COUNTING TECHNIQUES
EVEN-EVEN NUCLEI
ISOTOPES
LIGHT NUCLEI
MASS SPECTROSCOPY
MEASURING INSTRUMENTS
NUCLEI
PROPORTIONAL COUNTERS
RADIATION DETECTORS
RADIOISOTOPES
SPECTROSCOPY
YEARS LIVING RADIOISOTOPES