First isochronous mass spectrometry at the experimental storage ring ESR

Short-lived exotic nuclei can be produced and separated with the high-energ y secondary nuclear beam facility FRS at GSI. These nuclides can be injecte d and stored in the storage ring ESR. The lower lifetime limit of the prese ntly existing methods for mass measurements on these nuclides at the ESR is about a few seconds. We have developed and investigated an isochronous ope rational mode of the ESR, that makes mass measurements of nuclides with lif etimes down to a few Irs feasible. It has been commissioned in experiments using long-lived nuclides with known masses. A mass resolving power of abou t 150 000 has been achieved in a first pilot experiment. A suitable detecto r system has been implemented and commissioned at the ESR that allows measu rements of the revolution period of single particles within a few turns in the ESR. (C) 2000 Elsevier Science B.V. All rights reserved.