A CYCLOTRON AS A HIGH-RESOLUTION MASS-SPECTROMETER FOR FAST SECONDARY IONS

We present the first results from a new method for mass measurements developed using the GANIL coupled cyclotrons, which uses a cyclotron as a high resolution mass spectrometer for fast secondary ions. We report here the results obtained with primary beams of 13.74 MeV/nucleon N-15 and C-12, accelerated by the first cycltron and incident on a Ta target located between the cyclotrons. Reaction products with mass-to-charge ratio of 3 were selected and accelerated by the second cyclotron. The accelerated secondary nuclei were detected in the interior of the second cyclotron using a plastic scintillator located on a radially moving rod. Details of the procedure and results are discussed. When two masses are close enough to be accelerated simultaneously by the second cyclotron, the precision in the measurement of the mass difference is better than 10(-6).