Separated Oscillatory Fields for High-Precision Penning Trap Mass Spectrometry

Ramsey's method of separated oscillatory fields is applied to the excitation of the cyclotron motion of short-lived ions in a Penning trap to improve the precision of their measured mass. The theoretical description of the extracted ion-cyclotron-resonance line shape is derived out and its correctness demonstrated experimentally by measuring the mass of the short-lived $^{38}$Ca nuclide with an uncertainty of $1.6\cdot 10^{-8}$ using the ISOLTRAP Penning trap mass spectrometer at CERN. The mass value of the superallowed beta-emitter $^{38}$Ca is an important contribution for testing the conserved-vector-current hypothesis of the electroweak interaction. It is shown that the Ramsey method applied to mass measurements yields a statistical uncertainty similar to that obtained by the conventional technique ten times faster.Comment: 5 pages, 4 figures, 0 table

Magnetic field stabilization for high-accuracy mass measurements on exotic nuclides

The magnetic-field stability of a mass spectrometer plays a crucial role in precision mass measurements. In the case of mass determination of short-lived nuclides with a Penning trap, major causes of instabilities are temperature fluctuations in the vicinity of the trap and pressure fluctuations in the liquid helium cryostat of the superconducting magnet. Thus systems for the temperature and pressure stabilization of the Penning trap mass spectrometer ISOLTRAP at the ISOLDE facility at CERN have been installed. A reduction of the fluctuations by at least one order of magnitude downto dT=+/-5mK and dp=+/-50mtorr has been achieved, which corresponds to a relative frequency change of 2.7x10^{-9} and 1.5x10^{-10}, respectively. With this stabilization the frequency determination with the Penning trap only shows a linear temporal drift over several hours on the 10 ppb level due to the finite resistance of the superconducting magnet coils.Comment: 23 pages, 13 figure

The Ion Circus

International audienceThe study of exotic nuclides is chronically hampered by the overwhelming abundance of contamination, requiring the development of efficient instruments with good capacity for purification. We report on the first results of a novel circular ion trap designed to dynamically increase mass resolving power as the orbiting ions are cooled to avoid losses

Recent developments of the radioactive beam preparation at REX-ISOLDE

This year, three main topics of research and development have been pursued at the REX-ISOLDE facility low-energy stage, complementary to the energy upgrade of the postaccelerator. These concern the ion cooling method tests, the charge exchange process study in the buffer gas of the Penning trap REXTRAP, and the molecular beam injection into the trap and REXEBIS ion source. We report here on some progress in these different investigations

Towards a magnetic field stabilization at ISOLTRAP for high-accuracy mass measurements on exotic nuclides

The field stability of a mass spectrometer plays a crucial role in the accuracy of mass measurements. In the case of mass determination of short-lived nuclides with a Penning trap, major causes of fluctuations are temperature variations in the vicinity of the trap and pressure changes in the liquid helium cryostat of the superconducting magnet. Thus systems for the temperature and pressure stabilization of the Penning trap mass spectrometer ISOLTRAP at the ISOLDE facility at CERN have been installed. A reduction of the temperature and pressure fluctuations by at least an order of magnitude down to and has been achieved, which corresponds to a relative magnetic field change of ΔB/B=2.7×10-9 and 1.1×10-10, respectively

Recoil-ion trapping for precision mass measurements

status: publishe

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 Mn-61-63(+) and the daughter recoil-ions Fe-61-63(+) the Q values of Mn61-63 have been deduced with absolute uncertainties of about 5 keV. The observed yields of iron ions are compared to the results from simulations, which confirm a recoil-ion trapping efficiency of about 50%

Approaching the N=82N=82 shell closure with mass measurements of Ag and Cd isotopes

Expérience ISOLDEMass measurements of neutron-rich Cd and Ag isotopes were performed with the Penning trap mass spectrometer ISOLTRAP. The masses of 112,114−124Ag and 114,120,122−124,126,128Cd, determined with relative uncertainties between 2 × 10−8 and 2 × 10−7, resulted in significant corrections and improvements of the mass surface. In particular, the mass of 124Ag was previously unknown. In addition, other masses that had to be inferred from Q values of nuclear decays and reactions have now been measured directly. The analysis includes various mass differences, namely the two-neutron separation energies, the applicability of the Garvey-Kelson relations, double differences of masses δVpn, which give empirical proton-neutron interaction strengths, as well as a comparison with recent microscopic calculations. The δVpn results reveal that for even-even nuclides around 132Sn the trends are similar to those in the 208Pb region