9508413 Donahue An Accelerator Mass Spectrometer (AMS) using a 2 MV General Ionex tandem particle accelerator has been operated at the University of Arizona since 1981. The primary mission of this AMS laboratory is twofold. It operates as both a service laboratory to provide radiocarbon (l4C) determinations of samples of geophysical and archaeological importance to the scientific community at large, but also supports a wide range of in-house scientific research. The laboratory presently analyzes the l4C content of over 3,000 samples a year for many scientists from many parts of the world. Just under half of the current laboratory analyses are for in-house research, or for research undertaken in collaboration with external researchers. Such in-house research has focused on a diverse set of topics. Some of this research has been oriented toward improving AMS technology in terms of chemical preparation of samples, improvements to instrumentation and data reduction and interpretation. The labs efforts have enabled them to obtain unprecedented precision in l4C analyses. They currently are able to produce l4C/l3C ratios with measurement precisions of +0.5% in a counting time of about 30 minutes per sample, for recent material. High-precision measurements as accurate as +0.25% have been reported by this facility using multiple target determinations. Other in-house research projects are oriented towards more basic science goals including studies of in-situ production of 14C in rocks and ice and improvements to the l4C calibration curve using tree rings or coral l4CU-Th measurements. This grant supports operating and maintenance costs of the Arizona Accelerator Mass Spectrometer (AMS) laboratory and will allow them to maintain and improve the high standards of AMS measurements that the scientific community has come to expect from this facility, and to develop new applications of AMS, which will then be available to the scientific community. As part of this grant, Arizona will upgrade their existing AMS system with an injection system with an electrostatic analyzer, a high-resolution injection magnet, a fast isotope pulsing system, a high-energy analysis system with an electrostatic quadrupole lens, a 90 magnetic analyzer, and a cylindrical electrostatic analyzer. Support for the next International Conference on Accelerator Mass Spectrometry, to be held in Tucson in March 1996 is also included. ***
