High-precision Q-value and mass measurements for neutrino physics with TRIGA-TRAP and commissioning of an on-line ion source for TRIGA-SPEC

Der Nachweis des neutrinolosen doppelten Elektroneneinfangs kann zum Beweis des Majoranacharakters von Neutrinos verwendet werden. Übergänge mit einer Energieentartung zwischen dem Anfangs- und dem Endzustand weisen eine resonante Verstärkung der Zerfallsrate auf, so dass diese besonders für Experimente in der Neutrinophysik geeignet sind. Um solche resonanten Übergänge zu identifizieren, spielen genaue Q-Wert-Messungen mit Penningfallen-Massenspektrometern eine wichtige Rolle. In dieser Arbeit wurde die Resonanzbedingung des neutrinolosen doppelten Elektroneneinfangs in den Nukliden Cd-106, Cd-108, und Os-184 durch Q-Wert-Messungen mit dem Penningfallen-Massenspektrometer TRIGA-TRAP untersucht. Zusätzlich wurde der Q-Wert des doppelten Beta-Zerfalls in Pd-110 bestimmt. Desweiteren wurde eine Hochspannungsplattform und eine on-line Ionenquelle für die Ionisation von kurzlebigen neutronenreichen Spaltprodukten für das TRIGA-SPEC-Experiment am Forschungsreaktor TRIGA Mainz aufgebaut und erfolgreich in Betrieb genommen. Mit diesem Aufbau soll ein radioaktiver Ionenstrahl für hochpräzise Massenmessungen und kollineare Laserspektroskopie zur Verfügung gestellt werden. Die Spaltprodukte werden an Aerosole gebunden, um sie mit Hilfe eines Gasjet-Transportsystems vom Reaktor in die Ionenquelle zu transportieren. Dies stellt besondere Anforderungen an die Ionenquelle dar, da sie unter einer hohen Gaslast arbeiten und die Bindung zwischen Aerosolteilchen und Spaltprodukt aufbrechen muss. Es wurde untersucht, ob eine 2.45 GHz EZR-Ionenquelle für diesen Zweck geeignet ist

A reservoir trap for antiprotons

We have developed techniques to extract arbitrary fractions of antiprotons from an accumulated reservoir, and to inject them into a Penning-trap system for high-precision measurements. In our trap-system antiproton storage times > 1.08 years are estimated. The device is fail-safe against power-cuts of up to 10 hours. This makes our planned comparisons of the fundamental properties of protons and antiprotons independent from accelerator cycles, and will enable us to perform experiments during long accelerator shutdown periods when background magnetic noise is low. The demonstrated scheme has the potential to be applied in many other precision Penning trap experiments dealing with exotic particles.Comment: Article by the BASE-collaboration at CERN. Results from the Antiproton physics run 2014. Submitted to International Journal of Mass Spectrometry, 8th of April 201

Trap-integrated fluorescence detection based on silicon photomultipliers in a cryogenic Penning trap

We present a fluorescence-detection system for laser-cooled 9Be+ ions based on silicon photomultipliers (SiPM) operated at 4 K and integrated into our cryogenic 1.9 T multi-Penning-trap system. Our approach enables fluorescence detection in a hermetically-sealed cryogenic Penning-trap chamber with limited optical access, where state-of-the-art detection using a telescope and photomultipliers at room temperature would be extremely difficult. We characterize the properties of the SiPM in a cryocooler at 4 K, where we measure a dark count rate below 1/s and a detection efficiency of 2.5(3) %. We further discuss the design of our cryogenic fluorescence-detection trap, and analyze the performance of our detection system by fluorescence spectroscopy of 9Be+ ion clouds during several runs of our experiment.Comment: 12 pages, 11 figure

Precision measurements of the fundamental properties of the proton and antiproton

Precision measurements comparing the fundamental properties of conjugate particles and antiparticles constitute stringent tests of CPT invariance. We review recent precision measurements of the BASE collaboration, which improved the uncertainty of the proton and antiproton magnetic moments and the comparison of the proton-to-antiproton charge-to-mass ratio. These measurements constitute the most stringent tests of CPT invariance with antiprotons. Further, we discuss the improved limit on the antiproton lifetime based on the storage of a cloud of antiprotons in the unique BASE reservoir trap. Based on these recent advances, we discuss ongoing technical developments which comprise a coupling trap for the sympathetic cooling of single (anti-)protons with laser-cooled beryllium ions, a transportable trap to relocate antiproton measurements into a high-precision laboratory, and a new experiment to measure the magnetic moment of helium-3 ions, which will improve absolute precision magnetometry

Diagram and illustrations of parts of the BASE experiment

A number of illustrations of the parts of the BASE experiment, located in CERN's antimatter decelerator (AD)

Towards an improved measurement of the proton magnetic moment

The BASE collaboration performed the most precise measurement of the proton magnetic moment. By applying the so-called double Penning-trap method with a single proton a fractional precision of 3.3 parts-per-billion was reached. This article describes the primary limitations of the last measurement and discusses improvements to reach the sub-parts-per-billion level

A Test of Charge-Parity-Time Invariance at the Atto-Electronvolt Scale

We developed a novel fast measurement procedure for cyclotron frequency comparisons of two individual particles in a Penning trap, which enabled us to compare the charge-to-mass ratio of the proton and the antiproton with a fractional precision of 69 parts per trillion. To date this is the most precise test of charge-parity-time invariance using baryons. Our measurements were performed at cyclotron frequencies of about 30 MHz, which means that charge-parity-time symmetry holds at the atto-electronvolt scale