Study of the N=32 and N=34 Shell Gap for Ti and V by the First High-Precision Multireflection Time-of-Flight Mass Measurements at BigRIPS-SLOWRI.

The atomic masses of ^{55}Sc, ^{56,58}Ti, and ^{56-59}V have been determined using the high-precision multireflection time-of-flight technique. The radioisotopes have been produced at RIKEN's Radioactive Isotope Beam Factory (RIBF) and delivered to the novel designed gas cell and multireflection system, which has been recently commissioned downstream of the ZeroDegree spectrometer following the BigRIPS separator. For ^{56,58}Ti and ^{56-59}V, the mass uncertainties have been reduced down to the order of 10 keV, shedding new light on the N=34 shell effect in Ti and V isotopes by the first high-precision mass measurements of the critical species ^{58}Ti and ^{59}V.

Model independent peak fitting and uncertainty assignment for high-precision time-of-flight mass spectrometry.

A procedure is introduced to extract the time-of-flight probability density distribution for ions of one type using an accumulated ion peak as a template for use in the fitting of time-of-flight peaks of co-accumulated ions. We demonstrate the use of logarithmic splines and discuss the statistical criteria for the selection of the spline smoothing parameter to obtain a smooth function for approximating such an ion peak. Furthermore, a "Bootstrap" method is proposed to determine the uncertainty of the fitted time-of-flight values, which is calculated using the extracted peak shape via a repeated statistical experiment.

High-stability, high-voltage power supplies for use with multi-reflection time-of-flight mass spectrographs.

Achieving the highest possible mass resolving power in a multireflection time-of-flight mass spectrometer requires very high-stability power supplies. To this end, we have developed a programmable high-voltage power supply that can achieve long-term stability in the order of parts-per-million. Herein, we present the design of a stable high-voltage system and bench-top stability measurements up to 1 kV; a stabilization technique can, in principle, be applied up to 15 kV or more.

First Direct Mass Measurements of Nuclides around Z=100 with a Multireflection Time-of-Flight Mass Spectrograph.

The masses of ^{246}Es, ^{251}Fm, and the transfermium nuclei ^{249-252}Md and ^{254}No, produced by hot- and cold-fusion reactions, in the vicinity of the deformed N=152 neutron shell closure, have been directly measured using a multireflection time-of-flight mass spectrograph. The masses of ^{246}Es and ^{249,250,252}Md were measured for the first time. Using the masses of ^{249,250}Md as anchor points for α decay chains, the masses of heavier nuclei, up to ^{261}Bh and ^{266}Mt, were determined.

Hyperfine structure constant of the neutron halo nucleus (11)Be(+).

The hyperfine splittings of ground state Be+11 have been measured precisely by laser-microwave double resonance spectroscopy for trapped and laser cooled beryllium ions. The ions were produced at relativistic energies and subsequently slowed down and trapped at mK temperatures. The magnetic hyperfine structure constant of Be+11 was determined to be A11=-2677.