Recoil-ion trapping for precision mass measurements

For the first time masses of recoiling daughter ions have been measured that were held after beta-decay in a buffer-gas-filled Penning trap. From the masses of the trapped beta-decaying manganese ions 61-63Mn+ and the daughter recoil-ions 61-63Fe+ the Q values of 61-63Mn have been deduced with absolute uncertainties of about 5keV. The observed yields of iron ions are compared to the results from simulations, which confirm a recoil-ion trapping efficiency of about 50%.