Search

The 3³P state of positronium is an intermediate level suitable for producing long-lived positronium states. On one hand, it can be used in a two-step laser excitation scheme from the ground state to Rydberg levels. On the other hand, excitation of positronium to 3³P level is a simple pathway for producing metastable 2³S positronium atoms by spontaneous radiactive decay. In this work, experiments showing the production of such long-lived levels, using the 3³P state as intermediate state, are presented. The characteristics of the two long-lived levels, in view of experiments of deflectometry/interferometry with positronium, are discussed. [ABSTRACT FROM AUTHOR]

Forming a pulsed beam of cold antihydrogen using charge-exchange with Rydberg positronium (Ps) is the goal of the AEḡIS collaboration, which aims to a first gravity measurement on neutral antimatter. Recently achieved results in Ps formation and laser spectroscopy in the main AEḡIS apparatus are summarized. First, Ps has been produced using nanochanneled silicon targets in a cryogenic environment (~ 15 K) with 1 T magnetic field and observed by means of Single-Shot Positron Annihilation Lifetime Spectroscopy. The first demonstration of Ps n=3 excitation has been obtained as well using the same technique, validating the proof-of-concept of AEgIS. Subsequently, a new fast and high sensitivity detection method for laser-excited Ps in high magnetic field has been developed, using the combination of laser/field ionization and an high sensitivity MCP detector coupled to a low-noise CMOS camera. This technique will form the basis of future experiments involving Rydberg Ps spectroscopy in AEḡIS. [ABSTRACT FROM AUTHOR]

The AEgIS Experiment is an international collaboration based at CERN whose aim is to perform the first direct measurement of the gravitational acceleration g of antihydrogen in the gravitational field of the Earth. Cold antihydrogen will be produced with a pulsed charge exchange reaction in a cylindrical Penning trap where antiprotons will be cooled to 100mK. The cold antihydrogen will be produced in an excited Rydberg state and subsequently formed into a beam. The deflection of the antihydrogen beam will be measured by using Moiré deflectometer gratings. After being approved in late 2008, AEgIS started taking data in a commissioning phase early 2012. This report presents an overview of the AEgIS experiment, describes its current status and shows the first measurements on antiproton catching and cooling in the 5 T Penning catching trap. We will also present details on the techniques needed for the 100mK antihydrogen production, such as pulsed positronium production and its excitation with lasers. [ABSTRACT FROM AUTHOR]

The formation of the antihydrogen beam in the AEGIS experiment through the use of inhomogeneous electric fields is discussed and simulation results including the geometry of the apparatus and realistic hypothesis about the antihydrogen initial conditions are shown. The resulting velocity distribution matches the requirements of the gravity experiment. In particular it is shown that the inhomogeneous electric fields provide radial cooling of the beam during the acceleration. [ABSTRACT FROM AUTHOR]

We report on the formation of translationally cold Cs[sub 2] ground-state molecules through photoassociation of laser-cooled cesium atoms in a magneto-optical trap. The cold molecules are obtained after spontaneous decay of photoassociated molecules, and detected after pulsed-laser photoionization into Cs[sub 2][sup +] ions. Photoassociation spectra of cesium attractive molecular states below the 6S[sub 1/2]+6P[sub 3/2] dissociation limits are reported, obtained with both ion detection and trap-loss method. A temperature as low as 20[sub -5][sup +15] has been measured for the molecular cloud. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]