http://nuclearmasses.org/resources_folder/Blaum_06.pdf

High-accuracy mass spectrometry with stored ions

The mass of the nucleus, through its binding energy, continues to be of capital importance not only for various aspects of nuclear physics, but also for other branches of physics, notably weak-interaction studies and astrophysics. The authors first describe the modern experimental techniques dedicated to the particularly challenging task of measuring the mass of exotic nuclides and make detailed comparisons. Though tremendous progress in these and the associated production techniques has been made, allowing access to nuclides very far from stability, it is still not yet possible to produce many nuclides involved in stellar nucleosynthesis, especially the $r$ process, leaving no choice but to resort to theory. The review thus goes on to describe and critically compare the various modern mass formulas that may be used to extrapolate from the data towards the neutron drip line. Special attention is devoted to the crucial interplay between theory and experiment, showing how new measurements far from stability can considerably reduce the ambiguity in extrapolations to nuclides even further away.

Recent trends in the determination of nuclear masses

Atomic physics techniques for the determination of ground-state properties of radioactive isotopes are very sensitive and provide accurate masses, binding energies, Q-values, charge radii, spins and electromagnetic moments. Many fields in nuclear physics benefit from these highly accurate numbers. They give insight into details of the nuclear structure for a better understanding of the underlying effective interactions, provide important input for studies of fundamental symmetries in physics, and help to understand the nucleosynthesis processes that are responsible for the observed chemical abundances in the Universe. Penning-trap and storage-ring mass spectrometry as well as laser spectroscopy of radioactive nuclei have now been used for a long time but significant progress has been achieved in these fields within the last decade. The basic principles of laser spectroscopic investigations, Penning-trap and storage-ring mass measurements of short-lived nuclei are summarized and selected physics results are discussed.

https://iopscience.iop.org/article/10.1088/0031-8949/2013/T152/014017/pdf

Precision Atomic Physics Techniques for Nuclear Physics with Radioactive Beams

ISOLTRAP is a Penning trap mass spectrometer for high-precision mass measurements on short-lived nuclides installed at the on-line isotope separator ISOLDE at CERN. The masses of close to 300 radionuclides have been determined up to now. The applicability of Penning trap mass spectrometry to mass measurements of exotic nuclei has been extended considerably at ISOLTRAP by improving and developing this double Penning trap mass spectrometer over the past two decades. The accurate determination of nuclear binding energies far from stability includes nuclei that are produced at rates less than 100 ions/s and with half-lives well below 100ms. The mass-resolving power reaches 107 corresponding to 10keV for medium heavy nuclei and the uncertainty of the resulting mass values has been pushed down to below 10-8. The article describes technical developments achieved since 1996 and the present performance of ISOLTRAP.

/pdf/isoltrap-an-on-line-penning-trap-for-mass-spectrometry-on-1r7e6n702b.pdf

ISOLTRAP: An on-line Penning trap for mass spectrometry on short-lived nuclides

https://www.mpi-hd.mpg.de/blaum/files/esd2013/abstracts/ESD2013-I07.pdf

ISOLTRAP's multi-reflection time-of-flight mass separator/spectrometer

For a detailed study of the accuracy of the Penning trap mass spectrometer ISOLTRAP all expected sources of uncertainty were investigated with respect to their contributions to the uncertainty of the final result. In the course of these investigations, cross-reference measurements with singly charged carbon clusters 12C+
n were carried out. The carbon cluster ions were produced by use of laser-induced desorption, fragmentation, and ionization of C60 fullerenes and injected into and stored in the Penning trap system. The comparison of the cyclotron frequencies of different carbon clusters has provided detailed insight into the residual systematic uncertainty of ISOLTRAP and yielded a value of 8×10-9. This also represents the current limit of mass accuracy of the apparatus. Since the unified atomic mass unit is defined as 1/12 of the mass of the 12C atom, it will be possible to carry out absolute mass measurements with ISOLTRAP in the future.

/pdf/from-direct-to-absolute-mass-measurements-a-study-of-the-fnzzu9omut.pdf

From direct to absolute mass measurements: A study of the accuracy of ISOLTRAP

The cyclotron frequencies of singly charged carbon clusters C n + (n ≥ 2) were measured with the Penning-trap mass spectrometer ISOLTRAP at ISOLDE/CERN. The present limit of mass accuracy δm/m 1.2.10−8 and the extent of the mass-dependent systematic shift (δm/m)sys 1.7(0.6).10−10/u (m − m ref) of the setup were investigated for the first time. In addition, absolute mass measurements by use of pure clusters of the most abundant carbon isotope 12C are now possible at ISOLTRAP.

Carbon clusters for absolute mass measurements at ISOLTRAP

Cyclotron frequency measurements of singly charged carbon clusters 12C N + were carried out with the ISOLTRAP apparatus. The carbon cluster ions were produced externally by use of laserinduced desorption, fragmentation, and ionization of C60 fullerenes. They were injected into and stored in the Penning trap system. The observation of carbon clusters of different sizes has provided detailed insight into the final mass uncertainty achievable with ISOLTRAP and yielded a value of u(m)/m = 8 · 10-9. Since the unified atomic mass unit is defined as 1/12 the mass of the 12C atom, ISOLTRAP can now be used to carry out absolute mass measurements.

M. Kuckein

Papers

From direct to absolute mass measurements: A study of the accuracy of ISOLTRAP

Carbon clusters for absolute mass measurements at ISOLTRAP

Carbon Cluster Ions For a Study of the Accuracy of ISOLTRAP