Precision Penning trap mass measurements of rare isotopes produced by projectile fragmentation

Abstract

The low-energy beam and ion trap facility LEBIT at NSCL/MSU is at present the only facility where precision experiments are performed with stopped rare isotope beams produced by fast-beam fragmentation. LEBIT combines high-pressure-gas stopping with advanced ion manipulation techniques to provide brilliant low-energy beams. So far these beams have mainly been used for mass measurements on short-lived rare isotopes with a 9.4T Penning trap mass spectrometer. Recent examples include 70m Br , located at the proton dripline, 32Si and the iron isotopes 63-65Fe . While the measurement of 32Si helps to solve a long-standing dispute over the validity of the isobaric multiplet mass equation (IMME) for the A = 32 , T = 2 multiplet, the mass measurements of 65m,g Fe marked the first time a nuclear isomeric state has been discovered by Penning trap mass spectrometry.