[en] The mass excess of the superallowed β emitter ²⁶Si has been determined with the LEBIT Penning trap mass spectrometer to be -7140.4(2.9) keV, in agreement with recent measurements.

[en] The Low Energy Beam and Ion Trap (LEBIT) is the only present facility to combine high precision Penning trap mass spectrometry with fast beam projectile fragmentation. Located at the National Superconducting Cyclotron Laboratory (NSCL), LEBIT is able to measure radionuclides produced in a chemically independent process with minimal decay losses. Recent exotic mass measurements include ⁶⁶As, ^63-66Fe, and ³²Si. ⁶⁶As is a new candidate to test the Conserved Vector Current (CVC) hypothesis. The masses of the neutron-rich iron isotopes provide additional information about the mass surface and the subshell closure at N = 40. ³²Si is a member of the A = 32, T = 2 quintet; its measurement permits the most stringent test of the validity of the isobaric multiplet mass equation (IMME). An overview of some recent measurements will be presented as well as advanced techniques for ion manipulation.

[en] Rare isotope beams of many elements can be difficult or impossible to obtain at ISOL facilities due to their high melting points or chemical reactivity, but they are easily produced by projectile fragmentation and in-flight separation, a technique that rapidly produces fragments lighter than the projectile in a chemistry-free manner. Until recently, such high-energy projectile fragments could not be reduced to the thermal energies necessary for precision mass measurements in Penning traps. The Low Energy Beam and Ion Trap (LEBIT) facility at the National Superconducting Cyclotron Laboratory (NSCL) has demonstrated that projectile fragment beams can be thermalized and measured in a high-precision Penning trap. Since 2005, over 30 isotopes have been measured with LEBIT, including several isotopes of elements which are difficult for ISOL facilities to produce, such as Fe, Co, Si, Br, and S. These measurements have contributed to our understanding of nuclear structure, nuclear astrophysics, and fundamental symmetries. Some recent highlights include the discovery of an isomeric state in ⁶⁵Fe, testing the Isobaric Mass Multiplet Equation (IMME) with the A  =  32, T  =  2 quintet with a measurement of ³²Si, probing out to the proton dripline with ^70mBr, and studying the N  =  28 shell closure with measurements of ^{40 − 44}S. Results of these measurements will be discussed, along with the technical developments which made them possible.

[en] Masses of the radionuclides ^32,33Si and ³⁴P and of the stable nuclides ³²S and ³¹P have been measured with the Low Energy Beam and Ion Trap (LEBIT) Penning trap mass spectrometer. Relative mass uncertainties as low as 3x10^-9 have been achieved. The measured mass value of ³²Si differs from the literature value by four standard deviations. The precise mass determination of ³²Si and ³²S have been employed to test the validity of the quadratic form of the isobaric multiplet mass equation (IMME) for the most well known A=32, T=2 isospin quintet. The new experimental results indicate a dramatic breakdown of the model.

[en] Penning trap mass spectrometry is presented as a complementary tool to nuclear spectroscopy experiments for the study of nuclear structure in the vicinity of N=40, Z=28. High-precision mass measurements of the ^63-66Fe and ^64-67Co isotopes have been carried out with the Low Energy Beam and Ion Trap (LEBIT) Penning trap mass spectrometer. The newly obtained mass values for ⁶⁶Fe and ⁶⁷Co are presented, together with the previously reported LEBIT mass measurements in this region. In the case of ⁶⁵Fe the existence of a new isomer is reported, and an isomer recently discovered by decay spectroscopy in ⁶⁷Co is confirmed. Relative mass uncertainties as low as 4x10^-8 are obtained. All mass values are found to be in good agreement with previous experimental results with the exception of ⁶⁴Co, where a 5σ deviation is observed. Using these data the two neutron separation energies S_2n are calculated. However, the large error bars in the mass values of the neighbor Fe and Co isotopes with N>40 complicate the validation of a weak subshell closure at N=40 for the Co isotopes or the possible reduction in the neutron shell gap in the case of the Fe isotopes, in accordance with the theoretical predictions of an onset of deformation in the region.

[en] The LEBIT (Low Energy Beam and Ion Trap) facility is the only Penning trap mass spectrometry (PTMS) facility to utilize rare isotopes produced via fast-beam fragmentation. This technique allows access to practically all elements lighter than uranium, and in particular enables the production of isotopes that are not available or that are difficult to obtain at isotope separation on-line facilities. The preparation of the high-energy rare-isotope beam produced by projectile fragmentation for low-energy PTMS experiments is achieved by gas stopping to slow down and thermalize the fast-beam ions, along with an rf quadrupole cooler and buncher and rf quadrupole ion guides to deliver the beam to the Penning trap. During its first phase of operation LEBIT has been very successful, and new developments are now underway to access rare isotopes even farther from stability, which requires dealing with extremely short lifetimes and low production rates. These developments aim at increasing delivery efficiency, minimizing delivery and measurement time, and maximizing use of available beam time. They include an upgrade to the gas-stopping station, active magnetic field monitoring and stabilization by employing a miniature Penning trap as a magnetometer, the use of stored waveform inverse Fourier transform (SWIFT) to most effectively remove unwanted ions, and charge breeding.