A5054201840- Cold Atom Physics and Bose-Einstein Condensates
- Atomic and Molecular Physics
- Quantum, superfluid, helium dynamics
- Atomic and Subatomic Physics Research
- Advanced Chemical Physics Studies
- Muon and positron interactions and applications
- Quantum optics and atomic interactions
- Dark Matter and Cosmic Phenomena
- Advanced Frequency and Time Standards
- Quantum Information and Cryptography
- Spectroscopy and Laser Applications
- Quantum Mechanics and Applications
- Quantum and Classical Electrodynamics
- Particle physics theoretical and experimental studies
- Spectroscopy and Quantum Chemical Studies
- Particle accelerators and beam dynamics
- Quantum chaos and dynamical systems
- Corporate Finance and Governance
- Radioactive Decay and Measurement Techniques
- Entrepreneurship Studies and Influences
- Neutrino Physics Research
- Magnetic confinement fusion research
- Quantum Chromodynamics and Particle Interactions
- Particle Detector Development and Performance
- Urinary Bladder and Prostate Research
University College London
2015-2024
University of Liège
2021
University of Maryland, College Park
2021
Universidade da Coruña
2021
Barry University
2021
Virginia Tech
2021
Institute for Nuclear Research
2011-2014
European Organization for Nuclear Research
2014
ETH Zurich
2007-2013
University of South Wales
2011-2012
A three-dimensional trap for Rydberg atoms in selected Stark states has been realized experimentally. H seeded a supersonic expansion of Ar are excited to the low-field seeking n=30, k=25, |m|=0, 2 Rydberg-Stark states, decelerated from mean initial velocity 665 m/s zero laboratory frame and loaded into electrostatic trap. The motion cold atom cloud decay trapped have studied by pulsed electric field ionization imaging techniques.
The coherent interaction between ensembles of helium Rydberg atoms and microwave fields in the vicinity a solid-state coplanar waveguide is reported. Rydberg-Rydberg transitions, at frequencies 25 38 GHz, have been studied for states with principal quantum numbers range 30--35 by selective electric-field ionization. An experimental apparatus cooled to 100 K was used reduce effects blackbody radiation. Inhomogeneous, stray electric emanating from surface characterized frequency- time-resolved...
The AEGIS experiment, currently being set up at the Antiproton Decelerator CERN, has objective of studying free fall antimatter in Earth's gravitational field by means a pulsed cold atomic beam antihydrogen atoms. Both duration and vertical displacement horizontally emitted atoms will be measured, allowing first test WEP with antimatter.
Hydrogen molecules in selected core-nonpenetrating Rydberg-Stark states have been decelerated from a mean initial velocity of $500\text{ }\text{ }\mathrm{m}/\mathrm{s}$ to zero the laboratory frame and loaded into three-dimensional electrostatic trap. Trapping times, measured by pulsed electric field ionization trapped molecules, are found be limited collisional processes. As Rydberg can deexcited absolute ground state, method applied generate cold samples wide range species.
We consider some of the obstacles that will have to be overcome in order perform a direct measurement gravitational free-fall positronium atoms. Foremost among these are production atoms cryogenic environment, efficient excitation suitably long-lived Rydberg states, and their subsequent control via interaction large electric dipole moments with inhomogeneous fields. Recent developments all areas can directly applied gravity measurement, making such an endeavour both timely feasible.
We report a new measurement of the positronium (Ps) 2^{3}S_{1}→2^{3}P_{0} interval. Slow Ps atoms, optically excited to radiatively metastable 2^{3}S_{1} level, flew through microwave radiation field tuned drive transition short-lived 2^{3}P_{0} which was detected via time spectrum subsequent ground state annihilation radiation. After accounting for Zeeman shifts we obtain frequency ν_{0}=18501.02±0.61 MHz, is not in agreement with theoretical value ν_{0}=18498.25±0.08 MHz.
Hydrogen and deuterium atoms in supersonic jet expansions have been decelerated using a multistage Zeeman decelerator. The properties of the decelerator completely characterized series experiments which (i) initial longitudinal velocities atoms, (ii) maximum magnetic field strength, (iii) duration zero-field intervals between successive pulses neighboring deceleration stages were systematically varied. Experiments Ar Kr as carrier gases clearly revealed that H are located at surface...
We report the first experimental realization of magnetic trapping a sample cold radicals following multistage Zeeman deceleration pulsed supersonic beam. H atoms seeded in expansion Kr have been decelerated from an initial velocity $520\text{ }\text{ }\mathrm{m}/\mathrm{s}$ to $100\text{ 12-stage decelerator and loaded into quadrupole trap by rapidly switching fields solenoids.
Methods for the production of cold atomic and molecular samples relying on deceleration pulsed supersonic beams are described a review corresponding literature is presented. These methods include multistage Stark deceleration, Zeeman Rydberg–Stark deceleration. Recent applications produced with these techniques summarized.
Abstract Next generation tritium decay experiments to determine the absolute neutrino mass require high-precision measurements of β-decay electron energies close kinematic end point. To achieve this, development high phase-space density sources atomic is required, along with implementation methods control motion these atoms allow extended observation times. A promising approach efficiently and accurately measure kinetic individual electrons generated in dilute gases, frequency cyclotron...
Hydrogen atoms in supersonic expansions with velocities the range from $700\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}800\phantom{\rule{0.3em}{0ex}}\mathrm{m}∕\mathrm{s}$ have been excited to Rydberg-Stark states principal quantum number $n$ between 20 and 40, decelerated zero velocity lab frame using time-dependent inhomogeneous electric fields, trapped a two-dimensional electrostatic trap an initial density of...
Abstract Aims The aims of this study are to compile a list common features and artefacts found in urodynamics, produce definitions these features, describe any necessary remedial action. An image word description for each event has been included as well statistics providing information on the prevalence frequency event. Methods In order identify most 200 consecutive urodynamic traces were reviewed. A random 10% sample was cross‐checked ensure classification accuracy. To extract significant...
Hydrogen atoms in Rydberg states with principal quantum numbers between 23 and 70 have been accelerated, decelerated, electrostatically trapped using a surface-electrode Rydberg-Stark decelerator. By applying set of oscillating electrical potentials to two-dimensional array electrodes on printed circuit board (PCB), continuously moving, three-dimensional electric trap predefined velocity acceleration is generated. From an initial longitudinal $760\text{ }\text{ }\mathrm{m}/\mathrm{s}$, final...
Rydberg positronium (Ps) atoms have been prepared in selected Stark states via two-step (1s→2p→nd/ns) optical excitation. Two methods used to achieve Stark-state selection: a field ionization filter that transmits the outermost with positive shifts, and state-selected photoexcitation strong electric field. The former is demonstrated for n=17 18 while latter performed n=11 homogeneous of 1.9 kV/cm. observed spectral intensities their dependence on polarization laser radiation are agreement...
A supersonic beam of Rydberg hydrogen atoms has been adiabatically deflected by 90\ifmmode^\circ\else\textdegree\fi{}, decelerated to zero velocity in less than $25\text{ }\text{ }\ensuremath{\mu}\mathrm{s}$, and loaded into an electric trap. The deflection allowed the suppression collisions with trailing part gas pulse. processes leading trap losses, i.e., fluorescence ground state, transitions ionization induced blackbody radiation have monitored over several milliseconds quantitatively analyzed.
The main goal of the AEgIS experiment at CERN is to test weak equivalence principle for antimatter. will measure free-fall an antihydrogen beam traversing a moir\'e deflectometer. determine gravitational acceleration g with initial relative accuracy 1% by using emulsion detector combined silicon micro-strip time flight. Nuclear emulsions can annihilation vertex atoms precision about 1 - 2 microns r.m.s. We present here results detectors operated in vacuum low energy antiprotons from...
Rydberg helium atoms traveling in pulsed supersonic beams have been coupled to microwave fields a superconducting coplanar waveguide (CPW) resonator. The were initially prepared the $1s55s{\text{ }^{3}S}_{1}$ level by two-color two-photon laser excitation from metastable $1s2s\text{ }{^{3}S}_{1}$ level. Two-photon transitions between $1s55s\text{ and $1s56s\text{ levels then driven 19.556 GHz third-harmonic field quarter-wave CPW This resonator was fabricated niobium nitride on silicon...
We report the results of a new measurement positronium 2 ^{3}S_{1}→2 ^{3}P_{2} (ν_{2}) interval. Using modified experimental arrangement we have significantly reduced effects microwave reflections, which in previous experiments resulted shifts and asymmetric line shapes. With improved apparatus obtain an value ν_{2}=8627.94±0.95 MHz, is within 1.3σ theoretical 8626.71±0.08 MHz.
Translationally cold H(2) molecules excited to non-penetrating |M(J)| = 3 Rydberg states of principal quantum number in the range 21-37 have been decelerated and trapped using time-dependent inhomogeneous electric fields. The were prepared from X (1)Σ(+)(u)(v 0, J 0) ground state a resonant three-photon excitation sequence via B 3, 1) I (1)Π(g) (v 2) intermediate circularly polarized laser radiation. circular polarization vacuum ultraviolet radiation used for ← transition was generated by...
We report experiments in which positronium (Ps) atoms were guided using inhomogeneous electric fields. Ps Rydberg-Stark states with principal quantum number $n=10$ and dipole moments up to 610 D prepared via two-color two-photon optical excitation the presence of a $670\text{ }\text{ }\mathrm{V}\text{ }{\mathrm{cm}}^{\ensuremath{-}1}$ field. The created at entrance 0.4 m long electrostatic quadrupole guide, detected end guide annihilation gamma radiation. When lasers tuned excite...
We report measurements and the results of calculations demonstrating that annihilation dynamics positronium (Ps) atoms can be controlled by Stark Zeeman mixing optically excited states. In experiments a trap-based pulsed positron beam was employed to generate dilute Ps gas with density $\ensuremath{\sim}{10}^{7} \mathrm{cm}{}^{\ensuremath{-}3}$ using porous silica target. These were via...