Impact of buffer gas quenching on the S-1(0) -> P-1(1) ground-state atomic transition in nobelium

International audienceUsing the sensitive Radiation Detected Resonance Ionization Spectroscopy (RADRIS) techniquean optical transition in neutral nobelium (No, Z = 102) was identified. A remnant signal when delaying the ionizing laser indicated the influence of a strong buffer gas induced de-excitation of the optically populated level. A subsequent investigation of the chemical homologue, ytterbium (Yb, Z = 70), enabled a detailed study of the atomic levels involved in this process, leading to the development of a rate equation model. This paves the way for characterizing resonance ionization spectroscopy (RIS) schemes used in the studyof nobelium and beyond, where atomic properties are currently unknown

Many Body Structure of Strongly Interacting Systems

This carefully edited proceedings volume provides an extensive review and analysis of the work carried out over the past 20 years at the Mainz Microtron (MAMI). This research centered around the application of Quantum Chromodynamics in the strictly nonperturbative regime at hadronic scales of about 1 fm. Due to the many degrees of freedom in hadrons at this scale the leitmotiv of this research is "Many body structure of strongly interacting systems". Further, an outlook on the research with the forthcoming upgrade of MAMI is given. This volume is an authoritative source of reference for everyone interested in the field of the electro-weak probing of the structure of hadrons

On laser spectroscopy of the element nobelium (Z = 102)

Optical transitions were sought for in 254No, which was produced at the UNILAC accelerator at GSI in the reaction 208Pb (48Ca, 2n)254No. After separation from the projectile beam by the velocity filter SHIP, the nobelium ions were stopped inside a buffer gas cell and guided onto a tantalum filament. The activation energy for desorption of nobelium from tantalum was determined to be 246   (24) kJ/mol. In a first experiment, the search for the 7s7p1P1 level of nobelium by laser resonance ionization spectroscopy was started. Based on level predictions by multi-configuration Dirac-Fock and relativistic coupled-cluster calculations, the wavenumber ranges from 25   900 cm-1 to 28   260 cm-1 and from 28   040 cm-1 to 31   000 cm-1 were scanned with two excimer laser-pumped dye lasers and a frequency doubled Nd:YAG laser pumped OPO system, respectively. The measurements delivered no clear evidence for a resonance. However, five wavenumber positions, viz. 27   997 cm-1, 28   015 cm-1, 28   230 cm-1, 28   792 cm-1, and 29   516 cm-1, remain potential candidates for the transition and subject for upcoming investigations

A scheme for measuring the neutrino rest mass from the beta-decay of stored tritium atoms using a solenoid retardation spectrometer

A new type of electron spectrometer is under construction at Mainz University that allows a measurement of the β-spectrum of tritium with high resolution and transmission in order to determine the neutrino rest mass. It consists of a source that contains atomic tritium, trapped in a high magnetic field, and a solenoid retarding spectrometer

Precision measurement of the conversion electron spectrum of 83mKr with a solenoid retarding spectrometer

This paper reports on precision measurements of conversion lines in the decay of 83mKr with nuclear transition energies of 32.1 keV and 9.4 keV, respectively. The spectra were taken from a submonolayer surface of 83mKr frozen onto a cold backing, using the new Mainz solenoid retarding spectrometer. The high luminosity and resolution of this instrument enables the observation of all allowed conversion lines up to the N-shell and to fully separate the elastic component from inelastic satellites. The combined analysis of the data yields the transition energies Ey=32151.5±1.1 eV and 9405.9±0.8 eV, respectively. The experiment served also to pilot the application of this spectrometer to the question of a finite neutrino rest mass, searched for in the beta-decay spectrum of tritium and to problems in precision electron spectroscopy in general

Atom-at-a-time laser resonance ionization spectroscopy of nobelium

International audienceOptical spectroscopy of a primordial isotope has traditionally formed the basis for understanding the atomic structure of an element. Such studies have been conducted for most elements1 and theoretical modelling can be performed to high precision2, 3, taking into account relativistic effects that scale approximately as the square of the atomic number. However, for the transfermium elements (those with atomic numbers greater than 100), the atomic structure is experimentally unknown. These radioactive elements are produced in nuclear fusion reactions at rates of only a few atoms per second at most and must be studied immediately following their production4, which has so far precluded their optical spectroscopy. Here we report laser resonance ionization spectroscopy of nobelium (No; atomic number 102) in single-atom-at-a-time quantities, in which we identify the ground-state transition 1S0 1P1. By combining this result with data from an observed Rydberg series, we obtain an upper limit for the ionization potential of nobelium. These accurate results from direct laser excitations of outer-shell electrons cannot be achieved using state-of-the-art relativistic many-body calculations5, 6, 7, 8 that include quantum electrodynamic effects, owing to large uncertainties in the modelled transition energies of the complex systems under consideration. Our work opens the door to high-precision measurements of various atomic and nuclear properties of elements heavier than nobelium, and motivates future theoretical work