Beam steering with quasi-mosaic bent silicon single crystals : computer simulations for 855 MeV and 6.3 GeV electrons and comparison with experiments

Monte Carlo simulations have been performed for 855 MeV and 6.3 GeV electrons channeling in silicon single crystals at circular bent (111) planes. The aim was to identify critical experimental parameters which affect the volume-deflection and volume-capture characteristics. To these belongs the angular alignment of the crystal with respect to the nominal beam direction. The continuum potential picture has been utilized. The simulation results were compared with experiments. It turns out that the assumption of an anticlastic bending of the crystal, bent on the principle of the quasi-mosaic effect, is not required to reproduce the gross features of the experimental observations for two examined examples

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