Hydrogen Formation by Proton Impact on Positronium

Merrison, J. P.; Bluhme, H.; Chevallier, J.; Deutch, B. I.; Hvelplund, P.; Jørgensen, L. V.; Knudsen, H.; Poulsen, Mette Erecius; Charlton, M.

doi:10.1103/physrevlett.78.2728

Cited by 62 publications

(45 citation statements)

References 21 publications

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“…Rydberg Ps is clearly well-suited for such schemes since, in addition to the increased cross section, the long lifetimes will also allow for flexibility in an experiment [416]. Analogous processes can be studied without antiprotons via the charge conjugate reaction, i.e., hydrogen formation by Ps collisions with protons [433]. Similarly, one could use He + ions (which are even easier to produce than protons [434]) to measure charge-exchange neutralization following Rydberg Ps collisions with the ions.…”

Section: Excitation Of Rydberg Statesmentioning

confidence: 99%

Experimental progress in positronium laser physics

2018

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Abstract. The field of experimental positronium physics has advanced significantly in the last few decades, with new areas of research driven by the development of techniques for trapping and manipulating positrons using Surko-type buffer gas traps. Large numbers of positrons (typically ≥10 6 ) accumulated in such a device may be ejected all at once, so as to generate an intense pulse. Standard bunching techniques can produce pulses with ns (mm) temporal (spatial) beam profiles. These pulses can be converted into a dilute Ps gas in vacuum with densities on the order of 10 7 cm −3 which can be probed by standard ns pulsed laser systems. This allows for the efficient production of excited Ps states, including long-lived Rydberg states, which in turn facilitates numerous experimental programs, such as precision optical and microwave spectroscopy of Ps, the application of Stark deceleration methods to guide, decelerate and focus Rydberg Ps beams, and studies of the interactions of such beams with other atomic and molecular species. These methods are also applicable to antihydrogen production and spectroscopic studies of energy levels and resonances in positronium ions and molecules. A summary of recent progress in this area will be given, with the objective of providing an overview of the field as it currently exists, and a brief discussion of some future directions.

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Section: Excitation Of Rydberg Statesmentioning

confidence: 99%

Experimental progress in positronium laser physics

2018

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“…In addition, and in contrast to the case of reaction [Eq. (33)], the CPT-conjugate reaction has now been experimentally demonstrated (Merrison et al, 1997). Its principal problem is an extremely low recombination rate (ϳ10 h Ϫ1 per 10 10 low-energy positrons delivered from a separate accumulator to a Ps-forming solid surface).…”

Section: B Recombination Reactionsmentioning

confidence: 99%

Forty years of antiprotons

Eades

Hartmann

1999

Rev. Mod. Phys.

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The discovery of the antiproton some 40 years ago and the almost synchronous fall of parity (P) and charge conjugation (C) symmetries were soon followed by the realization that CPT rather than C invariance is the fundamental symmetry connecting matter and antimatter, and that consequently any measurement of the antiproton's properties can be interpreted as a test of that symmetry. It is the latter view of the antiproton, as an object of study in its own right, rather than as a means to such other ends as the production of gauge bosons and meson resonances, that is presented here. The authors review the technical steps that have led from the handful of antiprotons observed by Chamberlain, Segrè , Wiegand, and Ypsilantis to the intense, high-quality beams available today and show how the state of rest and isolation required for high precision measurements of their properties can be achieved by confining them in electromagnetic traps or in their microscopic counterparts, exotic atoms. The test bench role of antiprotons and antihydrogen atoms for both CPT symmetry and the gravitational weak equivalence principle is discussed, and the body of experimental results obtained since 1955 critically reviewed from this standpoint. Future experiments are then discussed in the light of the closure of the CERN Low Energy Antiproton Ring (LEAR), its replacement in 1999 by the Antiproton Decelerator (AD), and the likely antiproton source at the Japan Hadron Facility.[S0034-6861(99)00401-8] CONTENTS

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“…Thus, the device can be used to separate positrons from ions which have equal kinetic energies. This attribute was put to use in the experiment of Merrison et al 26,43 in which low energy positrons which had been liberated from a positronium atom following capture of the electron by a proton had to be distinguished from the much greater background of low energy protons. More typically it may be necessary to separate energetic positrons from ions which are almost at rest, having been created, for example, as a result of an ionizing collision with a gas atom or molecule.…”

Section: Discussion and Applicationsmentioning

confidence: 99%

Development and applications of time-bunched and velocity-selected positron beams

Merrison

Charlton

Aggerholm

et al. 2003

Review of Scientific Instruments

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We describe the development of an instrument for the production of low energy positron beams that are bunched in time, and the use of a velocity selection device. The bunching unit was constructed from forty seven separate elements, coupled in series in a capacitor chain to reduce the delay time for propagation of the applied voltage pulse along the electrode system and to facilitate operation at frequencies up to 100 kHz. A parabolic potential distribution for time focusing was used. Tests with a dc positron beam produced from a radioactive source are described, together with measurements in which the buncher was used to compress positron pulses produced from an electron accelerator-based beam. Computer simulations of particle trajectories in the buncher have been performed resulting in a detailed evaluation of the factors that govern and limit the time resolution of the instrument. A sector magnet used to velocity-select intermediate energy positrons is described and its performance discussed.

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Hydrogen Formation by Proton Impact on Positronium

Cited by 62 publications

References 21 publications

Experimental progress in positronium laser physics

Experimental progress in positronium laser physics

Forty years of antiprotons

Development and applications of time-bunched and velocity-selected positron beams

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