Radioisotope dating with accelerators

Radioisotope Dating with Accelerators Present Status and Future Prospects...R. A. Muller,... 

Muller R. A. (1979). Radioisotope dating with accelerators. Phys. Today, 32 23-28. 

Radioisotope Dating with Accelerators. Another area that has recently gained considerable attention involves use of an accelerator to perform measurements of radioactive atoms (20). In such cases, the... 

An early suggestion to use an accelerator to measure C directly was contained in the July 4,1976, issue of Astrophysical Notes, an internal publication of the UC Berkeley Space Sciences Laboratory, written by Muller and entitled Radioisotope Dating with a Cyclotron. An article with the same title appeared in the March 1977 issue of Science (16). In November 1977, simultaneous publication of the initial results of the C Van de Graaff measurements by a Simon Fraser-McMaster University collaborative effort (J7) and a University of Toronto-General lonex Corporation-University of Rochester consortium (18) appeared in Science. The culmination of the initial demonstrations of the possibility of direct C measurements was the First Conference on Radiocarbon Dating with Accelerators held at the University of Rochester in April 1978 (J9). 

Experiments performed to date with cyclotrons have used positive ions obtained from carbon dioxide and a gas ion source. This is an advantage in the sense that it permits standard pretreatment practices developed over the last 30 years at decay counting laboratories to be routinely employed up to the point of measurement (29). On the other hand, beam currents using gas ion sources are characteristically significantly less than those from the solid samples currently used with electrostatic type accelerators. In addition, memory effects, which make comparisons of a standard to an unknown difficult, have been reported. The first cyclotrons used for radioisotope measurements had previously been used extensively for nuclear physics experiments and the production of high energy ions. Because of these experiments, some cyclotron systems have apparently been contaminated. For the 88-in. Berkeley cyclotron, the construction of an external ion source was designed to attempt to overcome this problem. Unfortunately, the efficiency of the beam transport system in the external ion source introduced other problems (30). 

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