Protonium production in ATHENA

Abstract The ATHENA experiment at CERN, after producing cold antihydrogen atoms for the first time in 2002, has synthesised protonium atoms in vacuum at very low energies. Protonium, i.e. the antiproton–proton bound system, is of interest for testing fundamental physical theories. In the nested penning trap of the ATHENA apparatus protonium has been produced as result of a chemical reaction between an antiproton and the simplest matter molecule, H 2 + . The formed protonium atoms have kinetic energies in the range 40–700 meV and are metastable with mean lifetimes of the order of 1 μs. Our result shows that it will be possible to start measurements on protonium at low energy antiproton facilities, such as the AD at CERN or FLAIR at GSI

Dynamics of antiproton cooling in a positron plasma during antihydrogen formation

Abstract We demonstrate cooling of 10 4 antiprotons in a dense, cold plasma of ∼10 8 positrons, confined in a nested cylindrical Penning trap at about 15 K. The time evolution of the cooling process has been studied in detail, and several distinct types of behavior identified. We propose explanations for these observations and discuss the consequences for antihydrogen production. We contrast these results with observations of interactions between antiprotons and "hot" positrons at about 3000 K, where antihydrogen production is strongly suppressed

Measuring the free fall of antihydrogen

After the first production of cold antihydrogen by the ATHENA and ATRAP experiments ten years ago, new second-generation experiments are aimed at measuring the fundamental properties of this anti-atom. The goal of AEGIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) is to test the weak equivalence principle by studying the gravitational interaction between matter and antimatter with a pulsed, cold antihydrogen beam. The experiment is currently being assembled at CERN's Antiproton Decelerator. In AEGIS, antihydrogen will be produced by charge exchange of cold antiprotons with positronium excited to a high Rydberg state (n > 20). An antihydrogen beam will be produced by controlled acceleration in an electric-field gradient (Stark acceleration). The deflection of the horizontal beam due to its free fall in the gravitational field of the earth will be measured with a moire deflectometer. Initially, the gravitational acceleration will be determined to a precision of 1%, requiring the detection of about 105 antihydrogen atoms. In this paper, after a general description, the present status of the experiment will be reviewed

Exploring the WEP with a pulsed cold beam of antihydrogen

The AEGIS experiment, currently being set up at the Antiproton Decelerator at CERN, has the objective of studying the free fall of antimatter in the Earth's gravitational field by means of a pulsed cold atomic beam of antihydrogen atoms. Both duration of free fall and vertical displacement of the horizontally emitted atoms will be measured, allowing a first test of the WEP with antimatter

A study of the accuracy of the Penning trap mass spectrometer ISOLTRAP and Standard-Model tests with superallowed beta decays

ISOLTRAP ist ein Penningfallen-Massenspektrometer, das an dem on-line Isotopenseparator ISOLDE/CERN installiert ist. Es dient der Messung der atomaren Massen von kurzlebigen radioaktiven Nukliden. Die statistischen Meßungenauigkeiten einzelner Massenmessungen erreichen in etwa 10E-8. Mit Hilfe von Kohlenstoffcluster-Ionen, deren Massenverhältnisse exakt bekannt sind, wurden die unterschiedlichen Beiträge zur Gesamtmeßungenauigkeit einer Massenmessung untersucht. Aus diesen Messungen folgt, daß die erreichbare relative Genauigkeit von ISOLTRAP-Massenmessungen 8E-9 beträgt, mehr als eine Größenordnung besser als bisher angenommen. Unter Verwendung der neuen Meß- und Auswertungsprozedur, die sich aus dieser Untersuchung ergeben hat, wurde der Q-Wert des übererlaubten Beta-Zerfalls von Rb-74 über Massenmessungen des Mutter- und des Tochternuklids bestimmt. Mit einer Halbwertzeit von unter 65 ms ist Rb-74 das kurzlebigste Nuklid, das je in einer Penningfalle untersucht wurde. Dieses experimentelle Ergebnis hat es erlaubt, einen Beitrag zur Überprüfung der CVC-Hypothese (Erhaltung des Vektor-Stroms) der schwachen Wechselwirkung zu leisten, die ein Axiom des Standard-Modells ist. Es wurde außerdem dazu verwendet, berechnete Parameter, die für zukünftige noch strengere Tests benötigt werden, auf ihre Richtigkeit hin zu überprüfen

Pruebas de situaciones accidentales en combustible de HTR con el dispositivo Küfa (Accident testing of HTR fuel with the KÜFA device)

The ceramic and ceramic-like coating materials in modern high-temperature reactor fuel are designed to ensure mechanical stability and retention of fission products under normal and transient conditions, regardless of the radiation damage sustained in-pile. In hypothetical depressurization and loss-of-forced-circulation (D LOFC) accidents, fuel elements of modular high-temperature reactors are exposed to temperatures several hundred degrees higher than during normal operation, causing increased thermo-mechanical stress on the coating layers. At the Institute for Transuranium Elements of the European Commission, a vigorous experimental program is being pursued with the aim of characterizing the performance of irradiated HTR fuel under such accident conditions. A cold finger device (Küfa), operational in ITU¿s hot cells since 2006, has been used to perform heating experiments on eight irradiated HTR fuel pebbles from the AVR experimental reactor and from dedicated irradiation campaigns at the High-Flux Reactor in Petten, The Netherlands. Gaseous fission products are collected in a cryogenic charcoal trap, while volatiles are plated out on a water-cooled condensate plate. A quantitative measurement of the release is obtained by gamma spectroscopy. We highlight experimental results from the Küfa testing as well as the on-going development of new experimental facilities.JRC.DG.E.2-Hot cell

Study of the charge exchange process at low energy with REXTRAP

The efficiency of the radioactive-ion collection Penning trap REXTRAP at REX-ISOLDE has been studied for noble-gas ions cooled by collisions in a buffer gas of Ne atoms. The number of cooled ions has been recorded as a function of the cooling time. From these measurements, information concerning the charge exchange process between ions and atoms present in the buffer gas can be deduced