An emittance meter for pulsed, low-energy ion beams was developed. Based on the pepperpot method, the device is compact and portable. It has been installed at the S-EBIT Laboratory at AlbaNova, Stockholm University, to measure the emittance of highly charged ions extracted from the electron beam ion trap R-EBIT and the cooling trap of the high-precision Penning trap mass spectrometer SMILETRAP II. Using a fast delay-line anode detector, the emittance and time-of-flight of the extracted ions can be measured simultaneously. In this paper, design and data processing system are described and preliminary results are presented.

Externally, in an electron beam ion trap, generated Ar¹⁶⁺ ions were retrapped in a Penning trap and evaporatively cooled in their axial motion. The cooling was observed by a novel extraction technique based on the excitation of a coherent axial oscillation which yields short ion bunches of well-defined energies. The initial temperature of the ion cloud was decreased by a factor of more than 140 within 1 s, while the phase-space density of the coldest extracted ion pulses was increased by a factor of up to about 9.

The subject of this thesis is high-precision mass-measurements performed with Penning trap mass spectrometers (PTMS). In particular it describes the SMILETRAP I PTMS and the final results obtained with it, the masses of ⁴⁰Ca and that of the proton. The mass of ⁴⁰Ca is an indispensible input in the evaluation of measurements of the bound electron g-factor, used to test quantum electrodynamical calculations in strong fields. The value obtained agrees with available literature values but has a ten times higher precision.

The measurement of the proton mass, considered a fundamental physical constant, was performed with the aim of validating other Penning trap results and to test the limit of SMILETRAP I. It was also anticipated that a measurement at a relative precision close to 10^-10 would give insight in how to treat certain systematic uncertainties. The result is a value of the proton mass in agreement with earlier measurements and with an unprecedented precision of 1.8×10^-10.

Vital for the achieved precision of the proton mass measurement was the use of the Ramsey excitation technique. This technique, how it was implemented at SMILETRAP I and the benefits from it is discussed in the thesis and in one of the included papers.

The second part of the thesis describes the improved SMILETRAP II setup at the S-EBIT laboratory, AlbaNova. All major changes and upgrades compared to SMILETRAP I are discussed. This includes, apart from the Ramsey excitation technique, higher ionic charge states, improved temperature stabilization, longer run times, different reference ions, stronger and more stable magnetic field and a more efficient ion detection. Altogether these changes should reduce the uncertainty in future mass determinations by an order of magnitude, possibly down to 10^-11.

In order to reach relative uncertainties in mass measurements with Penning traps of 10^-10 or better, the temperature variation of the trap and surrounding materials must be kept below 10 mK. Temperature variations induce a shift in the measured ion cyclotron frequency because of non-zero, temperature dependent magnetic susceptibilities of the construction materials. In this paper we report of a new temperature regulation system recently installed at SMILETRAP II that manages to keep the temperature fixed at the set point with a standard deviation of only 2.6 mK. −10 or better, the temperature variation of the trap and surrounding.

Nuclear ground state properties including mass, charge radii, spins and moments can be determined by applying atomic physics techniques such as Penning-trap based mass spectrometry and laser spectroscopy. The MATS and LaSpec setups at the low-energy beamline at FAIR will allow us to extend the knowledge of these properties further into the region far from stability. The mass and its inherent connection with the nuclear binding energy is a fundamental property of a nuclide, a unique ""fingerprint"". Thus, precise mass values are important for a variety of applications, ranging from nuclear-structure studies like the investigation of shell closures and the onset of deformation, tests of nuclear mass models and mass formulas, to tests of the weak interaction and of the Standard Model. The required relative accuracy ranges from 10(-5) to below 10(-8) for radionuclides, which most often have half-lives well below 1 s. Substantial progress in Penning trap mass spectrometry has made this method a prime choice for precision measurements on rare isotopes. The technique has the potential to provide high accuracy and sensitivity even for very short-lived nuclides. Furthermore, ion traps can be used for precision decay studies and offer advantages over existing methods. With MATS (Precision Measurements of very short-lived nuclei using an Advanced Trapping System for highly-charged ions) at FAIR we aim to apply several techniques to very short-lived radionuclides: High-accuracy mass measurements, in-trap conversion electron and alpha spectroscopy, and trap-assisted spectroscopy. The experimental setup of MATS is a unique combination of an electron beam ion trap for charge breeding, ion traps for beam preparation, and a high-precision Penning trap system for mass measurements and decay studies. For the mass measurements, MATS offers both a high accuracy and a high sensitivity. A relative mass uncertainty of 10(-9) can be reached by employing highly-charged ions and a non-destructive Fourier-Transform Ion-Cyclotron-Resonance (FT-ICR) detection technique on single stored ions. This accuracy limit is important for fundamental interaction tests, but also allows for the study of the fine structure of the nuclear mass surface with unprecedented accuracy, whenever required. The use of the FT-ICR technique provides true single ion sensitivity. This is essential to access isotopes that are produced with minimum rates which are very often the most interesting ones. Instead of pushing for highest accuracy, the high charge state of the ions can also be used to reduce the storage time of the ions, hence making measurements on even shorter-lived isotopes possible. Decay studies in ion traps will become possible with MATS. Novel spectroscopic tools for in-trap high-resolution conversion-electron and charged-particle spectroscopy from carrier-free sources will be developed, aiming e. g. at the measurements of quadrupole moments and E0 strengths. With the possibility of both high-accuracy mass measurements of the shortest-lived isotopes and decay studies, the high sensitivity and accuracy potential of MATS is ideally suited for the study of very exotic nuclides that will only be produced at the FAIR facility. Laser spectroscopy of radioactive isotopes and isomers is an efficient and model-independent approach for the determination of nuclear ground and isomeric state properties. Hyperfine structures and isotope shifts in electronic transitions exhibit readily accessible information on the nuclear spin, magnetic dipole and electric quadrupole moments as well as root-mean-square charge radii. The dependencies of the hyperfine splitting and isotope shift on the nuclear moments and mean square nuclear charge radii are well known and the theoretical framework for the extraction of nuclear parameters is well established. These extracted parameters provide fundamental information on the structure of nuclei at the limits of stability. Vital information on both bulk and valence nuclear properties are derived and an exceptional sensitivity to changes in nuclear deformation is achieved. Laser spectroscopy provides the only mechanism for such studies in exotic systems and uniquely facilitates these studies in a model-independent manner. The accuracy of laser-spectroscopic-determined nuclear properties is very high. Requirements concerning production rates are moderate; collinear spectroscopy has been performed with production rates as few as 100 ions per second and laser-desorption resonance ionization mass spectroscopy (combined with beta-delayed neutron detection) has been achieved with rates of only a few atoms per second. This Technical Design Report describes a new Penning trap mass spectrometry setup as well as a number of complementary experimental devices for laser spectroscopy, which will provide a complete system with respect to the physics and isotopes that can be studied. Since MATS and LaSpec require high-quality low-energy beams, the two collaborations have a common beamline to stop the radioactive beam of in-flight produced isotopes and prepare them in a suitable way for transfer to the MATS and LaSpec setups, respectively.

We describe a refrigerated EBIT (R-EBIT) commissioned at the AlbaNova Research Center at Stockholm University. As an innovative solution, the superconducting magnet and the trapping drift tubes of the R-EBIT are cooled to a temperature of 4 K by a set of two cooling heads connected to helium compressors. This dry, i.e. liquid helium and liquid nitrogen free, system is easily operated and creates highly charged ions at a fraction of the cost of traditional liquid-cooled systems. A pulsed and continuous gas injection system was developed to feed neutral particles into the electron beam in the trap region. This improves significantly the highly charged ion production and R-EBIT performance. Fast extraction of ions from the R-EBIT yields very short ( < 100 ns), charge-separated ion bunches which can be either analysed using a straight time-of-flight section or sent to experimental beam lines following selection in a bending magnet. An emittance meter was used to measure the emittance of the ions extracted from the R-EBIT. The extracted ions were also re-trapped in a cylindrical Penning trap and properties of the re-trapped ions have been measured using the emittance meter. Results of these measurements are reported in this publication.

A new laboratory for highly charged ions is being built up at Stockholm University. A fully refrigerated electron beam ion trap (R-EBIT, 3 T magnet, 30 keV electron energy) was installed. It was used for spectroscopic studies, ion cooling experiments, electron ion collisions, and highly-charged ion surface studies. Here we report on an upgrade of this EBIT to a ``Super EBIT'' (S-EBIT, 4 T magnet, 260 keV electron energy). The high-voltage trapping system, the ion injection as well as the extraction scheme of S-EBIT and the LabView based operational system of S-EBIT are described.

Presently, a trapping system for cooling highly-charged ions (HCI) is being set up at AlbaNova at Stockholm University. The experiment aims at production of low temperature (emittance) HCI at very low energy. HCI are extracted from the new Stockholm EBIT (S-EBIT) before evaporative cooling is applied in a Penning trap. In the future the cooled ions will be injected into the precision trap of the high-precision mass spectrometer SMILETRAP II. In first tests the emittance of trapped ions was measured and it was shown that highly and low-charged ions could be simultaneously stored

We determine the cyclotron frequency ratio of H₂⁺ and D⁺, applying the two-pulse Ramsey-excitation technique in the Penning-trap mass spectrometer SMILETRAP. The final result, based on probing more than 100 000 ions, is a frequency ratio of 0.999 231 659 33(17). Using a value of the D⁺ mass recently measured by the Seattle group, we obtain so far the most precise experimental H₂⁺ mass value of 2.015 101 497 16(34) u. From this value a proton mass value of 1.007 276 466 95(18) u (0.18 ppb relative uncertainty) could be derived, in good agreement with the value of 1.007 276 466 89(14) u published by Van Dyck et al.

In this paper we describe the features of the SMILETRAP Penning trap mass spectrometer and give examples of recently performed precision mass measurements. SMILETRAP is designed for precision mass measurements using the merits of highly-charged ions. We emphasize here the importance of accurate masses of hydrogen-like and lithium-like ions for the evaluation of g-factor measurements of electrons bound to even–even nuclei and test quantum electrodynamics (QED). For these experiments the ion masses of ⁴⁰Ca¹⁷⁺ and ⁴⁰Ca¹⁹⁺ were measured at SMILETRAP with 5×10⁻¹⁰ precision. Highly precise mass measurements can also be used for testing atomic structure calculations and determination of atomic and nuclear binding energies. Some Q-values are of fundamental interest, for example, the beta-decay of tritium and the double beta-decay with no neutrinos of several nuclei, in particular ⁷⁶Ge. These decays are related to properties of the electron neutrino mass and whether this neutrino is a Majorana particle. The reason that Penning traps are so reliable for the determinations of accurate decay Q-values is due to the fact that systematic errors to a great deal cancel in the mass difference between the two atoms defining the Q-value. In this paper we report the most accurate Q-values of these two beta decays namely 18589.8(12) eV for the tritium decay, and 2038.997(46) keV for the neutrinoless double beta-decay of ⁷⁶Ge.