DESIGN CONSIDERATIONS FOR A FUTURE INJECTION SYSTEM FOR RADIOCARBON AMS MEASUREMENTS

In planning for a possible upgrade to the Oxford AMS system (dedicated to C-14 measurements), we have given thought to novel as well as conventional designs of injection which achieve both a high level of accuracy and also permit C-14 detection with negligible background due to misidentification. Experiments at Oxford in which sputtered beams from graphite are directly injected (no mass separation) give limits on the sufficient mass resolution to achieve unambiguous C-14 detection. These will be discussed. Our experience with the CO2 source indicates that space charge effects can become the dominant problem in achieving isotope ratio measurement accuracy and we believe should be taken into account in the design of high beam current systems. We will outline possible designs for a new system with these effects in mind. In particular, we hope to present a feasibility study for a pulsed magnet design.